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Wei Y, Bhuyan P, Kwon SJ, Kim S, Bae Y, Singh M, Thanh Tran D, Ha M, Jeong KU, Ma X, Park B, Park S. Liquid Metal Grid Patterned Thin Film Devices Toward Absorption-Dominant and Strain-Tunable Electromagnetic Interference Shielding. NANO-MICRO LETTERS 2024; 16:248. [PMID: 39017957 PMCID: PMC11255180 DOI: 10.1007/s40820-024-01457-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 06/10/2024] [Indexed: 07/18/2024]
Abstract
The demand of high-performance thin-film-shaped deformable electromagnetic interference (EMI) shielding devices is increasing for the next generation of wearable and miniaturized soft electronics. Although highly reflective conductive materials can effectively shield EMI, they prevent deformation of the devices owing to rigidity and generate secondary electromagnetic pollution simultaneously. Herein, soft and stretchable EMI shielding thin film devices with absorption-dominant EMI shielding behavior is presented. The devices consist of liquid metal (LM) layer and LM grid-patterned layer separated by a thin elastomeric film, fabricated by leveraging superior adhesion of aerosol-deposited LM on elastomer. The devices demonstrate high electromagnetic shielding effectiveness (SE) (SET of up to 75 dB) with low reflectance (SER of 1.5 dB at the resonant frequency) owing to EMI absorption induced by multiple internal reflection generated in the LM grid architectures. Remarkably, the excellent stretchability of the LM-based devices facilitates tunable EMI shielding abilities through grid space adjustment upon strain (resonant frequency shift from 81.3 to 71.3 GHz @ 33% strain) and is also capable of retaining shielding effectiveness even after multiple strain cycles. This newly explored device presents an advanced paradigm for powerful EMI shielding performance for next-generation smart electronics.
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Lee H, Ryu SH, Kwon SJ, Choi JR, Lee SB, Park B. Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites. NANO-MICRO LETTERS 2023; 15:76. [PMID: 36976370 PMCID: PMC10050308 DOI: 10.1007/s40820-023-01058-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 03/04/2023] [Indexed: 06/18/2023]
Abstract
Although there is a high demand for absorption-dominant electromagnetic interference (EMI) shielding materials for 5G millimeter-wave (mmWave) frequencies, most current shielding materials are based on reflection-dominant conductive materials. While there are few absorption-dominant shielding materials proposed with magnetic materials, their working frequencies are usually limited to under 30 GHz. In this study, a novel multi-band absorption-dominant EMI shielding film with M-type strontium ferrites and a conductive grid is proposed. This film shows ultralow EMI reflection of less than 5% in multiple mmWave frequency bands with sub-millimeter thicknesses, while shielding more than 99.9% of EMI. The ultralow reflection frequency bands are controllable by tuning the ferromagnetic resonance frequency of M-type strontium ferrites and composite layer geometries. Two examples of shielding films with ultralow reflection frequencies, one for 39 and 52 GHz 5G telecommunication bands and the other for 60 and 77 GHz autonomous radar bands, are presented. The remarkably low reflectance and thinness of the proposed films provide an important advancement toward the commercialization of EMI shielding materials for 5G mmWave applications.
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Chang MS, Kwon SJ, Jeong JW, Ryu SH, Jeong SJ, Lee K, Kim T, Yang S, Park CR, Park B, Kwon YT. Electromagnetic Wave Absorbing, Thermal-Conductive Flexible Membrane with Shape-Modulated FeCo Nanobelts. ACS APPLIED MATERIALS & INTERFACES 2022; 14:39255-39264. [PMID: 35975758 DOI: 10.1021/acsami.2c11094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Electromagnetic wave (EMW)-absorbing materials, manufactured with composites of magnetic particles, are essential for maintaining a high complex permeability and modulated permittivity for impedance matching. However, commonly available EMW-absorbing materials are unsatisfactory owing to their low complex permeability in the high-frequency band. Herein, we report a thin, flexible EMW-absorbing membrane comprising shape-modulated FeCo nanobelts/boron nitride nanoparticles, which enables enhanced complex permeability in the S, C, and X bands (2-12 GHz). The boron nitride nanoparticles that are introduced to the FeCo nanobelts demonstrate control of the complex permittivity, leading to an effective impedance matching close to 1, consequently resulting in a high reflection loss value of -42.2 dB at 12.0 GHz with only 1.6 mm thickness. In addition, the incorporation of boron nitride nanoparticles improves the thermal conductivity for the heat dissipation of the absorbed electromagnetic wave energy. Overall, the comprehensive study of nanomaterial preparation and shape modulation technologies can lead to the fabrication of an excellent EMW-absorbing flexible composite membrane.
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Jang MS, Chang MS, Kwon YT, Yang S, Gwak J, Kwon SJ, Lee J, Song K, Park CR, Lee SB, Park B, Jeong JW. High-throughput thermal plasma synthesis of Fe xCo 1-x nano-chained particles with unusually high permeability and their electromagnetic wave absorption properties at high frequency (1-26 GHz). NANOSCALE 2021; 13:12004-12016. [PMID: 34212957 DOI: 10.1039/d1nr01845k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Herein, we introduce novel 1-dimensional nano-chained FeCo particles with unusually-high permeability prepared by a highly-productive thermal plasma synthesis and demonstrate an electromagnetic wave absorber with exceptionally low reflection loss in the high-frequency regime (1-26 GHz). During the thermal plasma synthesis, spherical FeCo nanoparticles are first formed through the nucleation and growth processes; then, the high temperature zone of the thermal plasma accelerates the diffusion of constituent elements, leading to surface-consolidation between the particles at the moment of collision, and 1-dimensional nano-chained particles are successfully fabricated without the need for templates or a complex directional growth process. Systematic control over the composition and magnetic properties of FexCo1-x nano-chained particles also has been accomplished by changing the mixing ratio of the Fe-to-Co precursors, i.e. from 7 : 3 to 3 : 7, leading to a remarkably high saturation magnetization of 151-227 emu g-1. In addition, a precisely-controlled and uniform surface SiO2 coating on the FeCo nano-chained particles was found to effectively modulate complex permittivity. Consequently, a composite electromagnetic wave absorber comprising Fe0.6Co0.4 nano-chained particles with 2.00 nm-thick SiO2 surface insulation exhibits dramatically intensified permeability, thereby improving electromagnetic absorption performance with the lowest reflection loss of -43.49 dB and -10 dB (90% absorbance) bandwidth of 9.28 GHz, with a minimum thickness of 0.85 mm.
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Wu C, Wang H, Li Y, Kim T, Kwon SJ, Park B, He Z, Lee SB, Um MK, Byun JH, Chou TW. Sensitivity Improvement of Stretchable Strain Sensors by the Internal and External Structural Designs for Strain Redistribution. ACS APPLIED MATERIALS & INTERFACES 2020; 12:50803-50811. [PMID: 33135419 DOI: 10.1021/acsami.0c13427] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Fiber strain sensors that are directly woven into smart textiles play an important role in wearable systems. These sensors require a high sensitivity to detect the subtle strain in practical applications. However, traditional fiber strain sensors with constant diameters undergo homogeneous strain distribution in the axial direction, thereby limiting the sensitivity improvement. Herein, a novel strategy of internal or external structural design is proposed to significantly improve the sensitivity of fiber strain sensors. The fibers are produced with directional increases in diameter (internal design) or polydimethylsiloxane (PDMS) microbeads attached to surfaces (external design) by combining hollow glass tubes used as templates with PDMS drops. The structural modification of the fiber significantly impacts the sensing performance. After optimizing structural parameters, the highest gauge factor reaches 123.1 in the internal-external structure design at 25% strain. A comprehensive analysis reveals that the desirable scheme is the internal structural design, which features a high sensitivity of 110 with a 100% improvement at ∼5-20% strain. Because of the sufficiently robust interface, even at the 800th cycle, fiber sensors still possessed an excellent stable performance. The morphology evolution mechanism indicates that the resistance increase is closely related with the increased peak width and distance, and the appearance of gaps. Based on the finite element modeling simulation, the quantified effective contributions of different strategies positively correlate with the improved sensitivity. The proposed fiber strain sensors, which are woven into the two-dimensional network structure, exhibit an excellent capability for displacement monitoring and facilitate the traffic control of crossroads.
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Kwon SJ, Jung BM, Kim T, Byun J, Lee J, Lee SB, Choi UH. Influence of Al2O3 Nanowires on Ion Transport in Nanocomposite Solid Polymer Electrolytes. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01603] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Park B, Kim T, Jeon S, Kwon SJ, Jang HK, Jung BM, Ahn SK, Choi UH, Lee J, Lee SB. Influence of intermolecular interactions on molecular geometry and physical quantities in electrolyte systems. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1543905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Kwon SJ, Kim T, Jung BM, Lee SB, Choi UH. Multifunctional Epoxy-Based Solid Polymer Electrolytes for Solid-State Supercapacitors. ACS APPLIED MATERIALS & INTERFACES 2018; 10:35108-35117. [PMID: 30230315 DOI: 10.1021/acsami.8b11016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Solid polymer electrolytes (SPEs) have drawn attention for promising multifunctional electrolytes requiring very good mechanical properties and ionic conductivity. To develop a safe SPE for energy storage applications, mechanically robust cross-linked epoxy matrix is combined with fast ion-diffusing ionic liquid/lithium salt electrolyte (ILE) via a simple one-pot curing process. The epoxy-rich SPEs show higher Young's modulus ( E), with higher glass transition temperature ( Tg) but lower ionic conductivity (σdc) with a higher activation energy, compared to the ILE-rich SPEs. The incorporation of inorganic robust Al2O3 nanowire simultaneously provides excellent mechanical robustness ( E ≈ 1 GPa at 25 °C) and good conductivity (σdc ≈ 2.9 × 10-4 S/cm at 25 °C) to the SPE. This suggests that the SPE has a bicontinuous microphase separation into ILE-rich and epoxy-rich microdomain, where ILE continuous conducting phases are intertwined with a sturdy cross-linked amorphous epoxy framework, supported by the observation of the two Tgs and low tortuosity as well as the microstructural investigation. After assembling the SPE with activated carbon electrodes, we successfully demonstrate the supercapacitor performance, exhibiting high energy and power density (75 W h/kg at 382 W/kg and 9.3 kW/kg at 44 W h/kg). This facile strategy holds tremendous potential to advance multifunctional energy storage technology for next-generation electric vehicles.
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Hwang GT, Palneedi H, Jung BM, Kwon SJ, Peddigari M, Min Y, Kim JW, Ahn CW, Choi JJ, Hahn BD, Choi JH, Yoon WH, Park DS, Lee SB, Choe Y, Kim KH, Ryu J. Enhancement of Magnetoelectric Conversion Achieved by Optimization of Interfacial Adhesion Layer in Laminate Composites. ACS APPLIED MATERIALS & INTERFACES 2018; 10:32323-32330. [PMID: 30168328 DOI: 10.1021/acsami.8b09848] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report the effect of epoxy adhesion layers with different mechanical or physical property on a magnetoelectric (ME) composite laminate composed of FeBSi alloy (Metglas)/single-crystal Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3/Metglas to achieve an improved ME conversion performance. Through theoretical simulation, it was revealed that the Young's modulus and the thickness of interfacial adhesives were major parameters that influence the conversion efficiency in ME composites. In the experimental evaluation, we utilized three epoxy materials with a distinct Young's modulus and adjusted the average thickness of the adhesion layers to optimize the ME conversion. The experimental results show that a thin epoxy layer with a high Young's modulus provided the best performance in the inorganic-based ME conversion process. By tailoring the interfacial adhesion property, the ME laminate generated a high conversion coefficient of 328.8 V/(cm Oe), with a mechanical quality factor of 132.0 at the resonance mode. Moreover, we demonstrated a highly sensitive alternating current magnetic field sensor that had a detection resolution below 10 pT. The optimization of the epoxy layers in the ME laminate composite provided significant enhancement of the ME response in a simple manner.
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Jung B, Seo KS, Kwon SJ, Lee K, Hong S, Seo H, Kim GY, Park GM, Jeong J, Seo S. Efficacy evaluation of syringe pump developed for continuous drug infusion. J Dent Anesth Pain Med 2016; 16:303-307. [PMID: 28879319 PMCID: PMC5564196 DOI: 10.17245/jdapm.2016.16.4.303] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 12/30/2016] [Accepted: 12/31/2016] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND In dental intravenous sedation, continuous intravenous infusion of a low-dose drug requires an infusion pump such as a syringe pump. To develop a new syringe pump for clinical use, the functions of the pump must meet certain international standards. Various safety and efficacy tests must be performed on the syringe pump, as stipulated by these standards, and an approval must be received from the approving agency based on such test results. METHODS The authors of the present study developed a novel syringe pump and performed efficacy evaluation by testing its infusion speed at 1 and 25 ml/h, and infusion performance testing at 2 and 24 h. Moreover, performance evaluation was conducted by comparing the novel pump to an existing pump with the infusion speed varied from 1 to 5 ml/h. RESULTS In the efficacy testing on the newly developed syringe pump, infusion with the infusion speed initially set to 1 ml/h resulted in infusion speeds of 1.00 and 0.99 ml/h in the 2- and 24-h assessment, respectively. Changing the infusion speed setting to 25 ml/h resulted in an infusion speed of 25.09 and 23.92 ml/h in the 2- and 24-h assessment, respectively. These results show no significant differences when compared with other commercially available pumps. CONCLUSIONS The efficacy testing of the newly developed syringe pump showed the accuracy to be within tolerance. Based on these findings, we believe that the newly developed syringe pump is suitable for clinical use.
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Ryu J, Im SB, Kwon SJ, Ahn JW, Jeong SW, Kang SY. Chemical and genetic diversity of high-seed-yield sorghum (Sorghum bicolor M.) germplasms. GENETICS AND MOLECULAR RESEARCH 2016; 15:gmr8677. [PMID: 27706704 DOI: 10.4238/gmr.15038677] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
This study evaluated the chemical and genetic diversity of high-seed-yield sorghum germplasms from Korea, the United States, and South Africa. We identified significant differences in the chemical contents of whole plants at the heading stage in all cultivars, including differences in crude protein, fat, fiber, ash, neutral detergent fiber, acid detergent fiber, mineral, and fatty acid contents. Our results suggest that Banwoldang is the most appropriate cultivar for roughage because of its high protein yield. We identified significant differences in the tannin, flavonoid, amylose, mineral, crude fat, fatty acid, and 3-deoxyanthocyanin contents in the whole grain from all cultivars, but not in the mineral or crude fat contents. Tannin levels were generally low. IS645 contained the highest levels of flavonoids and linolenic acid compounds, and Moktak had the highest amylose and deoxyanthocyanidin content in the grain. To assess genetic diversity, we used 10 simple sequence repeat (SSR) primer sets to identify 38 alleles with 3-8 alleles per locus. Based on phylogenetic analysis of the SSR markers, the sorghum cultivars were divided into three major groups. Comparison of clusters based on chemical compositions with those based on SSRs showed that the groups formed by the three native Korean cultivars clustered similarly in molecular dendrograms. Association analysis was conducted for the 10 SSR marker; 48 chemical and growth traits were present for two marker traits (seed color and whole plant fatty acid content) with significant marker-trait associations. These markers could be used to select sorghum cultivars for breeding programs.
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Chung HS, Lee S, Kwon SJ, Park CS. Perioperative predictors for refractory hyperglycemia during the neohepatic phase of liver transplantation. Transplant Proc 2015; 46:3474-80. [PMID: 25498075 DOI: 10.1016/j.transproceed.2014.06.078] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 06/17/2014] [Indexed: 01/15/2023]
Abstract
BACKGROUND Hyperglycemia in the neohepatic phase of liver transplantation (LT) tends to decrease toward completion of the surgical procedure. Refractory hyperglycemia in the neohepatic phase (RH) is influenced by multiple perioperative factors and may be connected to posttransplant outcomes. We attempted to demonstrate the relationship of RH to posttransplant outcomes and to establish a predictive model for RH in living donor liver transplantation (LDLT). METHODS Perioperative data of 211 patients who underwent LDLT from 2009 and 2012 were reviewed, including declines in the blood glucose levels during the neohepatic phase. Perioperative variables including the posttransplant model for end-stage liver disease (MELD) score until day 30 were compared between patients with normal declines in blood glucose and patients with RH. Selected variables after intergroup comparisons were examined by means of multivariate logistic regression to establish a predictive model for RH occurrence. RESULTS The mean blood glucose decline was 22.3 ± 31.5 mg/dL during the neohepatic phase, and 84 of 203 patients (41.4%) had no decline in blood glucose. In intergroup comparisons, preoperative factors associated with RH included sex, Child-Pugh-Turcotte class, MELD score, emergency, liver enzymes, and graft-to-recipient weight ratio. During surgery, surgical time, serum lactate, and arterial pH were associated with RH. After surgery, the RH group showed slower recovery of the MELD score (15.2 versus 11.9 days) and higher MELD scores until day 10 (P < .05). After the multivariate analysis, recipient sex, emergency, surgical time (≤9 h), and the final intraoperative serum lactate level (≥5.0 mmol/L) were included in the predictive model for RH. CONCLUSIONS RH was associated with delayed functional recovery of the liver graft in LT. Recipient sex, emergency, surgical time, and the final intraoperative serum lactate level were identified as predictors of RH. Close monitoring of intraoperative blood glucose in LDLT may be an early prognostic indicator.
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Chi SI, Lee SE, Seo KS, Choi YJ, Kim HJ, Kim HJ, Han JH, Han HJ, Lee EH, Oh A, Kwon SJ. Telephone follow-up care for disabled patients discharged after receiving dental treatment under outpatient general anesthesia. J Dent Anesth Pain Med 2015; 15:5-10. [PMID: 28879252 PMCID: PMC5564069 DOI: 10.17245/jdapm.2015.15.1.5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 04/03/2015] [Accepted: 04/03/2015] [Indexed: 11/16/2022] Open
Abstract
Background Patients were subjected to post-discharge follow-up (by telephone) in order to investigate the potential complications of outpatient general anesthesia or deep sedation that could develop in disabled dental patients discharged from the hospital. The ultimate aim of this study was to establish an appropriate response measure for such complications. Methods The caregivers of 79 disabled patients who underwent dental procedures under general anesthesia at our outpatient clinic were interviewed over telephone. Necessary care instructions were provided during the phone calls when required. The patient satisfaction level regarding the telephonic follow-up care was surveyed by additional telephone calls. Results Most of the patients did not suffer any serious complications; however, some reported fever and bleeding. The data obtained in this study can be utilized towards the development of caregiver education pertaining to the ambulatory general anesthesia of dental patients with disabilities. Conclusions Additionally, we hope that the findings of this study will help minimize the effects of complications experienced by disabled dental patients undergoing ambulatory general anesthesia, as well as increase the overall patient satisfaction level.
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Lee HW, Hyung GW, Koo JR, Cho ES, Kwon SJ, Park JH, Kim YK. Effect of an organic buffer layer on the stability of zinc oxide thin-film transistors. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2014; 14:5070-5074. [PMID: 24757982 DOI: 10.1166/jnn.2014.8425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Compared with other materials, zinc oxide (ZnO) exhibits stability in air, high-electron mobility, transparency and low light sensitivity. We investigated these properties in ZnO thin-film transistors (TFTs) containing a cross-linked poly(vinyl alcohol) (C-PVA) (1:3) buffer layer stacked between the semiconductor and gate dielectric. We measured the impact of this C-PVA layer on gate bias stress. We measured the transfer characteristics of the saturation region to determine the threshold voltage and the field-effect mobility of the transistors. We recorded a threshold voltage of 11.53 V in the ZnO TFTs with the C-PVA buffer layer, the field-effect mobility was 0.2 cm2/Vs. There was a positive shift in the threshold voltage of deltaV(TH) approximately 10 V in response to the application of a gate bias stress of 20 V. The positive shift in the threshold voltage was lower than that in pristine ZnO TFTs. This finding suggests that the shift in threshold voltage was due to reduced charge trapping at the semiconductor-gate dielectric interface. Our report indicates that the organic buffer layer enhanced the stability of ZnO TFTs.
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Sim SY, Jeon HS, Chung GS, Kim SK, Kwon SJ, Lee WK, Park KS. Fall detection algorithm for the elderly using acceleration sensors on the shoes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:4935-8. [PMID: 22255445 DOI: 10.1109/iembs.2011.6091223] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The rate of increase in the number of aging population in Korea is very rapid among OECD-member countries. And fall accident is one of the most common factors that threaten the health of the elderly. Therefore, it is needed to develop a fall detection system for the elderly. Most fall detection systems use accelerometers attached on the torso. And in various studies, it was verified that these systems have high sensitivity and high specificity. However, the elderly would feel uncomfortable when banding a sensor on the chest every day. Therefore, in this study, we attached an accelerometer on the shoes to detect fall in the elderly. This prototype system would be improved as a smaller, low-power system in the next study. Also, applying energy harvesting device to this shoe system is being developed to reduce the weight of battery.
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Jeon T, Seo D, Kwon SJ, Kang J. Quantitative PCR for etiologic diagnosis of methicillin-resistant Staphylococcus aureus pneumonia in intensive care unit. BMC Proc 2011. [PMCID: PMC3239801 DOI: 10.1186/1753-6561-5-s6-p66] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Yang JK, Kim YS, Kim KI, Koo HS, Kim SM, Lee TH, Im EH, Huh KC, Choi YW, Kang YW, Kwon SJ. A case of esophageal and endobronchial anthracosis. Endoscopy 2010; 42 Suppl 2:E150-1. [PMID: 20486083 DOI: 10.1055/s-0029-1215417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
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Han K, Lee JE, Kwon SJ, Park SY, Shim SH, Kim H, Moon JH, Suh CS, Lim HJ. Human amnion-derived mesenchymal stem cells are a potential source for uterine stem cell therapy. Cell Prolif 2008; 41:709-25. [PMID: 18823496 DOI: 10.1111/j.1365-2184.2008.00553.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
OBJECTIVES Human amnion is an easy-to-obtain novel source of human mesenchymal stem cells, which poses little or no ethical dilemmas. We have previously shown that human amnion-derived mesenchymal (HAM) cells exhibit certain mesenchymal stem cell-like characteristics with respect to expression of stem cell markers and differentiation potentials. MATERIALS AND METHODS In this study, we further characterized HAM cells' potential for in vivo therapeutic application. RESULTS Flow cytometric analyses of HAM cells show that they express several stem cell-related cell surface markers, including CD90, CD105, CD59, CD49d, CD44 and HLA-ABC, but not CD45, CD34, CD31, CD106 or HLA-DR. HAM cells at the 10th passage showed normal karyotype. More interestingly, the AbdB-like HOXA genes HOXA9, HOXA10 and HOXA11 that are expressed in the mesenchyme of the developing female reproductive tract and pregnant uteri are also expressed in HAM cells, suggesting similarities between these two mesenchymal cell types. Progesterone receptor is also highly expressed in HAM cells and expression of genes or proteins in HAM cells could be manipulated with the aid of lentivirus technology or cell-permeable peptides. To test potentials of HAM cells for in vivo application, we introduced enhanced green fluorescence protein (EGFP)-expressing HAM cells to mice by intrauterine infusion (into uteri) or by intravenous injection (into the circulation). Presence of EGFP-expressing cells within the uterine mesenchyme after intrauterine infusion or in lungs after intravenous injection was noted within 1-4 weeks. CONCLUSIONS Collectively, these results suggest that HAM cells are a potential source of mesenchymal stem cells with therapeutic potential.
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Lee SH, Bae HJ, Kwon SJ, Kim H, Kim YH, Yoon BW, Roh JK. Cerebral microbleeds are regionally associated with intracerebral hemorrhage. Neurology 2004; 62:72-6. [PMID: 14718700 DOI: 10.1212/01.wnl.0000101463.50798.0d] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Cerebral microbleeds (CMB) may be indicative of a hemorrhage-prone microangiopathy. OBJECTIVE To determine if increased numbers of these lesions are predictive of intracerebral hemorrhage (ICH), especially in terms of a distributional association. METHODS The authors examined consecutively 227 patients with acute stroke. CMB were counted using T2*-weighted gradient echo MRI data, and old lacunes and leukoaraiosis were also evaluated. The associations between the vascular risk factors and ICH were analyzed. With use of multivariate logistic regression analysis, the locations of the CMB or the old lacunes, which were categorized as being in the corticosubcortical area, the deep gray matter area, or the infratentorial area, were examined with regard to their relationships to the locations of the ICH. RESULTS The degrees of the CMB (r = 0.43, p < 0.01) and leukoaraiosis (r = 0.20, p < 0.01) were well correlated with the presence of ICH. Multivariate analysis revealed that the grades of the CMB were associated with the presence of ICH (p < 0.01, odds ratio [OR] = 2.67). CMB in the corticosubcortical area (p < 0.01, OR = 5.50) or deep gray matter (p < 0.01, OR = 2.55) were strongly associated with the presence of ICH in the same area, but no such association was observed in the case of CMB in the infratentorial area or in the case of old lacunes in any area. CONCLUSIONS Cerebral microbleeds are strongly associated with the presence of intracerebral hemorrhage, and the distributional associations are also quite strong.
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Kwon SJ, Ko SY. Orthogonally protected, enantiopure syn-2-amino-1,3,4-butanetriol: a general building block for syn-amino alcohols. J Org Chem 2001; 66:6833-5. [PMID: 11578247 DOI: 10.1021/jo015886j] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Son KH, Kwon SJ, Chang HW, Kim HP, Kang SS. Papyriflavonol A, a new prenylated flavonol from Broussonetia papyrifera. Fitoterapia 2001; 72:456-8. [PMID: 11395279 DOI: 10.1016/s0367-326x(00)00329-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A new prenylated flavonol, papyriflavonol A, was isolated from the root barks of Broussonetia papyrifera. The structure of this compound was elucidated as 5,7,3',4'-tetrahydroxy-6,5'-di-(gamma,gamma-dimethylallyl)-flavonol (1) by spectroscopic analysis.
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Park JW, Kwon SJ, Ryu JS, Hong EK, Lee JU, Yu HJ, Ahn MH, Min DY. Two imported cases of cutaneous larva migrans. THE KOREAN JOURNAL OF PARASITOLOGY 2001; 39:77-81. [PMID: 11301593 PMCID: PMC2721068 DOI: 10.3347/kjp.2001.39.1.77] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Cutaneous larva migrans (CLM) is a rare serpiginous cutaneous eruption caused by accidental penetration and migration in the skin with infective larvae of nematode that normally do not have the human as their host. Although CLM has a worldwide distribution, the infection is most frequent in warmer climates. More recently, they have been increasingly imported from the tropics or subtropics by travelers. We experienced two patients who had pruritic serpiginous linear eruption in their skin for a few weeks after traveling to the endemic areas (Brazil and Thailand, respectively). After the treatment with albendazole, the skin lesions resolved with post-inflammatory hyperpigmentation. We report herein two cases of cutaneous larva migrans successfully treated with albendazole.
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Abstract
Morphologic studies of gastric stromal tumors (GSTs) indicate that mitotic counts (MCs) and tumor size are major discriminants predictive of biologic behavior. The purpose of this study is to improve the understanding of GST behavior, including the prognostic factors and surgical treatment of GSTs. A retrospective analysis (1990--1997) of the clinical course for 116 patients with GSTs was completed, with a median follow-up of 43 months. Tumors were categorized as malignant GSTs (n = 17) when the MC was > 5/50 high-power fields (HPF) and the size > 5 cm or as benign GSTs (n = 99) when the MC was < or = 5/50 HPF and the size < or = 5 cm, MC < or = 5/50 HPF and size > 5 cm, or MC > 5/50 HPF and size < or = 5 cm. None of 99 benign tumors recurred or metastasized, whereas 7 of 17 malignant tumors recurred. MCs had a close correlation with tumor size. Immunohistochemical studies using CD34, smooth muscle actin, S-100 protein, and synaptophysin have shown positive rates of 61%, 33%, 14%, and 3%, respectively. Smooth muscle actin reactivity was more common in the benign tumors (p = 0.046) and synaptophysin reactivity in the malignant tumors (p = 0.010). Univariate analysis showed that the following clinicopathologic factors were potentially related to poor survival of patients: (1) MC > 5/50 HPF (p = 0.0001); (2) severe pleomorphism (p = 0.0062); (3) necrosis (p = 0.0173); (4) marked cellularity (p = 0.0112); (5) presence of ulceration of overlying gastric mucosa (p = 0.0091); (6) tumor size > 5 cm (p = 0.0195); and (7) exogastric growth pattern (p = 0.0344). Tumors with MC > 5/50 HPF and size > 5 cm were found to be strong indicators of an unfavorable prognosis. The type of surgery and tumor site did not affect the prognosis of the patients.
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Hong F, Kwon SJ, Jhun BS, Kim SS, Ha J, Kim SJ, Sohn NW, Kang C, Kang I. Insulin-like growth factor-1 protects H9c2 cardiac myoblasts from oxidative stress-induced apoptosis via phosphatidylinositol 3-kinase and extracellular signal-regulated kinase pathways. Life Sci 2001; 68:1095-105. [PMID: 11228094 DOI: 10.1016/s0024-3205(00)01012-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Oxidative stress plays a critical role in cardiac injuries during ischemia/reperfusion. Insulin-like growth factor-1 (IGF-1) promotes cell survival in a number of cell types, but the effect of IGF-1 on the oxidative stress has not been elucidated in cardiac muscle cells. Therefore, we examined the role of IGF-1 signaling pathway in cell survival against H2O2-induced apoptosis in H9c2 cardiac myoblasts. H2O2 treatment induced apoptosis in H9c2 cells, and pretreatment of cells with IGF-1 suppressed apoptotic cell death. The antiapoptotic effect of IGF-1 was blocked by LY294002 (an inhibitor of phosphatidylinositol 3-kinase) and by PD98059 (an inhibitor of extracellular signal-regulated kinase (ERK)). The protective effect of IGF-1 was also blocked by rapamycin (an inhibitor of p70 S6 kinase). Furthermore, H9c2 cells stably transfected with constitutively active PI 3-kinase (H9c2-p110*) and Akt (H9c2-Gag-Akt) constructs were more resistant to H2O2 cytotoxicity than control cells. Although H2O2 activates both p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK), IGF-1 inhibited only JNK activation. Activated PI 3-kinase (H9c2-p110*) and pretreatment of cells with IGF-1 down-regulated Bax protein levels compared to control cells. Taken together, our results suggest that IGF-1 transmits a survival signal against oxidative stress-induced apoptosis in H9c2 cells via PI 3-kinase and ERK-dependent pathways and the protective effect of IGF-1 is associated with the inhibition of JNK activation and Bax expression.
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Abstract
We describe a 54-year-old patient with an unusual localization of localized multiple glomus tumors. She had several nodules on the left mandibular area, lower lip, and anterior part of the buccal mucosa. A biopsy taken from the left mandibular area showed cystically dilated vessels lined by endothelial cells and a few outer layers of glomus cells in the dermis to subcutis. Localized multiple glomus tumors are rare, and both their facial and oral mucocal localization are extremely rare.
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