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Son JY, Lee KY, Lee SH, Choi CH. Effects of Oxidized Metal Powders on Pore Defects in Powder-Fed Direct Energy Deposition. MICROMACHINES 2024; 15:243. [PMID: 38398972 PMCID: PMC10893081 DOI: 10.3390/mi15020243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 02/25/2024]
Abstract
Laser-based additive manufacturing processes, particularly direct energy deposition (DED), have gained prominence for fabricating complex, functionally graded, or customized parts. DED employs a high-powered heat source to melt metallic powder or wire, enabling precise control of grain structures and the production of high-strength objects. However, common defects, such as a lack of fusion and pores between layers or beads, can compromise the mechanical properties of the printed components. This study focuses on investigating the recurrent causes of pore defects in the powder-fed DED process, with a specific emphasis on the influence of oxidized metal powders. This research explores the impact of intentionally oxidizing metal powders of hot work tool steel H13 by exposing them to regulated humidity and temperature conditions. Scanning electron microscopy images and energy-dispersive X-ray spectroscopy results demonstrate the clumping of powders and the deposition of iron oxides in the oxidized powders at elevated temperatures (70 °C for 72 h). Multi-layered depositions of the oxidized H13 powders on STD61 substrate do not show significant differences in cross sections among specimens, suggesting that oxidation does not visibly form large pores. However, fine pores, detected through CT scanning, are observed in depositions of oxidized powders at higher temperatures. These fine pores, typically less than 250 µm in diameter, are irregularly distributed throughout the deposition, indicating a potential degradation in mechanical properties. The findings highlight the need for careful consideration of oxidation effects in optimizing process parameters for enhanced additive manufacturing quality.
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Kim NY, Kim JM, Son JY, Ra CH. Synbiotic Fermentation of Undaria pinnatifida and Lactobacillus brevis to Produce Prebiotics and Probiotics. Appl Biochem Biotechnol 2023; 195:6321-6333. [PMID: 36862333 DOI: 10.1007/s12010-023-04415-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/17/2023] [Indexed: 03/03/2023]
Abstract
It has been optimized thermal acid hydrolytic pretreatment and enzymatic saccharification (Es) in flask culture of Undaria pinnatifida seaweed, which is a prebiotic. The optimal hydrolytic conditions were a slurry content of 8% (w/v), 180 mM H2SO4, and 121°C for 30 min. Es using Celluclast 1.5 L at 8 U/mL produced 2.7 g/L glucose with an efficiency of 96.2%. The concentration of fucose (a prebiotic) was 0.48 g/L after pretreatment and saccharification. The fucose concentration decreased slightly during fermentation. Monosodium glutamate (MSG) (3%, w/v) and pyridoxal 5'-phosphate (PLP) (30 μM) were added to enhance gamma-aminobutyric acid (GABA) production. To further improve the consumption of mixed monosaccharides, adaptation of Lactobacillus brevis KCL010 to high concentrations of mannitol improved the synbiotic fermentation efficiency of U. pinnatifida hydrolysates.
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Burrows K, Anderson GB, Yan M, Wilson A, Sabath MB, Son JY, Kim H, Dominici F, Bell ML. Health disparities among older adults following tropical cyclone exposure in Florida. Nat Commun 2023; 14:2221. [PMID: 37076480 PMCID: PMC10115860 DOI: 10.1038/s41467-023-37675-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 03/27/2023] [Indexed: 04/21/2023] Open
Abstract
Tropical cyclones (TCs) pose a significant threat to human health, and research is needed to identify high-risk subpopulations. We investigated whether hospitalization risks from TCs in Florida (FL), United States, varied across individuals and communities. We modeled the associations between all storms in FL from 1999 to 2016 and over 3.5 million Medicare hospitalizations for respiratory (RD) and cardiovascular disease (CVD). We estimated the relative risk (RR), comparing hospitalizations during TC-periods (2 days before to 7 days after) to matched non-TC-periods. We then separately modeled the associations in relation to individual and community characteristics. TCs were associated with elevated risk of RD hospitalizations (RR: 4.37, 95% CI: 3.08, 6.19), but not CVD (RR: 1.04, 95% CI: 0.87, 1.24). There was limited evidence of modification by individual characteristics (age, sex, or Medicaid eligibility); however, risks were elevated in communities with higher poverty or lower homeownership (for CVD hospitalizations) and in denser or more urban communities (for RD hospitalizations). More research is needed to understand the potential mechanisms and causal pathways that might account for the observed differences in the association between tropical cyclones and hospitalizations across communities.
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Son JY, Lee KY, Shin GY, Choi CH, Shim DS. Mechanical and Thermal Properties of the High Thermal Conductivity Steel (HTCS) Additively Manufactured via Powder-Fed Direct Energy Deposition. MICROMACHINES 2023; 14:872. [PMID: 37421105 DOI: 10.3390/mi14040872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/13/2023] [Accepted: 04/14/2023] [Indexed: 07/09/2023]
Abstract
High thermal conductivity steel (HTCS-150) is deposited onto non-heat-treated AISI H13 (N-H13) via powder-fed direct energy deposition (DED) based on the response surface methodology (RSM) to enhance the mechanical properties and thermal conductivity of N-H13, which is generally used as a hot-work tool steel. The main process parameters of the powder-fed DED are priorly optimized to minimize defects in the deposited regions and, therefore, to obtain homogeneous material properties. The deposited HTCS-150 is comprehensively evaluated through hardness, tensile, and wear tests at the different temperatures of 25, 200, 400, 600, and 800 °C. Compared to conventionally heat-treated (quenched and tempered) H13 (HT-H13), the hardness of the additively manufactured HTCS-150 slightly increases at 25 °C, whereas it does not show any significant difference above 200 °C. However, the HTCS-150 deposited on N-H13 shows a lower ultimate tensile strength and elongation than HT-H13 at all tested temperatures, and the deposition of the HTCS-150 on N-H13 enhances the ultimate tensile strength of N-H13. While the HTCS-150 does not show a significant difference in the wear rate below 400 °C compared to HT-H13, it shows a lower wear rate above 600 °C. The HTCS-150 reveals a higher thermal conductivity than the HT-H13 below 600 °C, whereas the behavior is reversed at 800 °C. The results suggest that the HTCS-150 additively manufactured via powder-fed direct energy deposition can enhance the mechanical and thermal properties of N-H13, including hardness, tensile strength, wear resistance, and thermal conductivity in a wide range of temperatures, often superior to those of HT-H13.
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Lee SH, Shim HS, Cho SH, Kim SY, Lee SK, Son JY, Jung JY, Kim EY, Lim JE, Lee KJ, Park BH, Kang YA, Kim YS, Kim SK, Chang J, Park MS. Prognostic factors for idiopathic pulmonary fibrosis: clinical, physiologic, pathologic, and molecular aspects. SARCOIDOSIS, VASCULITIS, AND DIFFUSE LUNG DISEASES : OFFICIAL JOURNAL OF WASOG 2011; 28:102-112. [PMID: 22117501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
BACKGROUND Previous studies identified clinical and physiologic factors of idiopathic pulmonary fibrosis (IPF) that are related to an increased risk of mortality. But there are few studies about histologic and molecular approach. OBJECTIVE We investigated whether the C-reactive protein (CRP), fibroblastic foci, phosphorylated Smad2/3 (p-Smad2/3), tumor growth factor-beta (TGF-beta), TGF-beta receptor II (TbetaRII), and the polymorphism of the TGF-beta1 codon 10 are associated with the progression of IPF patients. DESIGN Eighty-six IPF patients who underwent surgical lung biopsies were examined. For each patient, clinical and physiologic parameters were investigated, and we performed immunohistochemical staining for p-Smad2/3 and TbetaRII, and genotyping of the TGF-beta1 codon 10 polymorphism. RESULTS Age at diagnosis, gender, symptom duration, and smoking status did not show a significant association. However, the amount of smoking (p = 0.002), severe reduction in the percentages of predicted forced vital capacity (p = 0.013) and diffusion lung capacity of carbon monoxide (p = 0.023), CRP (p = 0.009) at diagnosis, and fibroblastic foci (p = 0.026) were associated with a poor prognosis. Cellularity, fibrosis, expression level of p-Smad2/3 and TbetaRII, and genotype of the TGF-beta1 codon 10 polymorphism did not have a statistically significant association with the prognosis. CONCLUSION This study confirmed the amount of smoking, abrupt decrease in follow-up pulmonary function parameters, fibroblastic foci, and increased levels of CRP concentration at diagnosis were significantly associated with poor survival. Larger studies are required to confirm all prognostic factors including CRP.
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Hong HO, Abanto OD, Kim KH, Nam KT, Son JY, Jung WS, Nam IS, Hwang SG. The Effects of Dietary Soybean Fermented with Aspergillus oryzae or Bacillus natto on Egg Production and Egg Lipid Composition in Layer. Korean J Food Sci Anim Resour 2010. [DOI: 10.5851/kosfa.2010.30.4.609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Son JY, Shin YH, Kim H, Cho JH, Jang H. Kelvin probe force microscopy for conducting nanobits of NiO thin films. NANOTECHNOLOGY 2010; 21:215704. [PMID: 20431198 DOI: 10.1088/0957-4484/21/21/215704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We demonstrated the writing and reading of conducting nanobits on a NiO thin film deposited on Pt/TiO(2)/SiO(2)/Si substrates for a resistive random access memory (RRAM) application using conducting atomic force microscopy (CAFM) and Kelvin probe force microscopy (KFM). A Pt/NiO/Pt RRAM capacitor showed a typical unipolar switching behavior with bistable resistances. Conducting nanobits with diameters of 22 nm written with a bias of 3.0 V on the NiO thin film were observed with CAFM. The conducting nanobits observed by KFM exhibited negative potentials relative to the insulating regions when there was no bias at the Pt bottom electrode because image charges were induced by charges formed at the end of the KFM tip by the reference AC bias. Enhancement of the KFM signals for conducting nanobits was achieved using specific biases at the Pt bottom electrode, which provided clear KFM images for conducting nanobits.
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Lee OH, Lee BY, Lee J, Lee HB, Son JY, Park CS, Shetty K, Kim YC. Assessment of phenolics-enriched extract and fractions of olive leaves and their antioxidant activities. BIORESOURCE TECHNOLOGY 2009; 100:6107-6113. [PMID: 19608415 DOI: 10.1016/j.biortech.2009.06.059] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 04/20/2009] [Accepted: 06/14/2009] [Indexed: 05/28/2023]
Abstract
Recent studies suggest that olive leaf is a significant source of bioactive phenolic compounds comparable to olive oil and fruits. Identifying appropriate extraction methods is thus an important step to increase the yield of such bioactive components from olive leaf, which is otherwise agricultural waste. The present study evaluates phenolic contents and compositions of olive leaf extracted by several solvent methods and to further establish their antioxidant activities using various radical scavenging systems. Total flavonoid and phenolic contents were significantly higher in the 80% ethanol extract, butanol, and ethylacetate fractions than hexane, chloroform and water fractions (p<0.05). Oleuropein was identified as a major phenolic compound with considerable contents in these major three fractions and the extract that correlated with their higher antioxidant and radical scavenging. These results indicate that olive leaf contains significant amounts of oleuropein and phenolics, important factors for antioxidant capacity, which can be substantially modified by different extraction methods.
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Chung WY, Kim SK, Son JY. Isoflavones Contents and Physiological Activities of Soybeans Fermented with Aspergillus oryzae or Bacillus natto. ACTA ACUST UNITED AC 2008. [DOI: 10.3746/jkfn.2008.37.2.141] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Son JY, Shestak SA, Epikhin VM, Chun JH, Kim SK. Multichannel acousto-optic Bragg cell for real-time electroholography. APPLIED OPTICS 1999; 38:3101-3104. [PMID: 18319897 DOI: 10.1364/ao.38.003101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A multichannel acousto-optic Bragg cell was made by the joining of acousto-optic cells that have the shape of symmetrical trapezoidal prisms. This acousto-optic Bragg cell has an aperture length equal to the sum of its component acousto-optic cells but has an aperture time equal to that of each acousto-optic cell. We tested the performance of the multichannel acousto-optic Bragg cell by joining six TeO(2) acousto-optic cells together with 300-microm gaps between one another. The holographic fringe data prepared by computer were divided into six equal segments. Each data segment was again divided into six equal parts and then fed into the corresponding acousto-optic cell. The holographic images were reconstructed by the periodical illumination of a green (lambda = 0.5145 microm) pulse laser beam onto the multichannel acousto-optic Bragg cell. The reconstructed images are sharp and clear. This indicates that the multichannel acousto-optic Bragg cell is working properly.
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Kim JS, Smirnov VV, Son JY, Chun YS, Im TG. Visual method of measuring reflection-type characteristics of holographic optical elements. APPLIED OPTICS 1998; 37:8258-8263. [PMID: 18301648 DOI: 10.1364/ao.37.008258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A highly diverging laser beam is used to measure angular and spectral selectivities and grating vector direction for reflection-type holographic optical elements (HOE's). The intensity distribution of the beam transmitted from the HOE's reveals dark, ring-shaped patterns. Since these ring patterns are formed as a result of the beam diffracted by the HOE's, the thicknesses and the diameters of the ring patterns convey information on both the angular and the spectral selectivities of the HOE's. In addition the deviation of the ring centers relative to the center of the intensity distribution reveals the grating vector direction. Determination of values related to the ring patterns permits highly accurate measurement of HOE characteristics, such as the upper limit of the diffraction wavelength, the angular and the spectral selectivities, and the grating vector direction. This is proved experimentally.
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Hwang SH, Bobrinev VI, Son JY, Shestak SA, Jeon HW. Achromatized transmission-type holographic screen for a multiview stereoscopic image system. APPLIED OPTICS 1997; 36:6605-6610. [PMID: 18259521 DOI: 10.1364/ao.36.006605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The main drawback of the use of transmission-type holographic screens is poor color reproduction caused by their high spectral dispersion. For overcoming this drawback, a long, narrow diffusing slit is used as an object when recording the screen. The necessary size and position of the slit relative to the photoplate and to the recording and reconstruction beams are determined by the phase relations of the beams. By use of the slit, holographic screens of 30 cm x 40 cm are recorded with a diverging reference beam and are used to display a multiview full-color stereoscopic image. The images displayed on the screen show no sign of color separation except near the edges of the screen. The image brightness on the screen is high enough that it can be watched in a normally illuminated room.
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Son JY, Bobrinev VI, Jeon HW, Cho YH, Eom YS. Direct image transmission through a multimode optical fiber. APPLIED OPTICS 1996; 35:273-277. [PMID: 21069009 DOI: 10.1364/ao.35.000273] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
One-way transmission of a multipixel image through the multimode optical fiber based on the phase-conjugation principle is realized. Adistortion-compensating hologram for each pixel of an image to be transmitted is superposed on a photoplate. Each hologram is recorded with a reference beam of different beam incidence angle to provide proper wave-front correction for each pixel without any interference from other pixels. The reference beams are holographically generated from a photoplate in which small holographic lenslets are aligned in a matrix pattern. Images of up to 25 pixels are transmitted through the fiber experimentally.
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Son JY, Jeon HW, Choi YJ, Kostrov NA. Optimization of a three-dimensional object composite Fourier hologram. OPTICS LETTERS 1995; 20:776-778. [PMID: 19859326 DOI: 10.1364/ol.20.000776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
It was found that the optimum subhologram dimension of the composite Fourier-transform hologram for minimizing image blur depends on object depth and information reduction ratio. Optimization of the subhologram dimension permits us to calculate the parameters of the composite Fourier-transform hologram for its applications to hologram transmission systems and to electroholographic three-dimensional displays.
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Son JY, Farmer WM, Giel TV. New optical geometry for the particle sizing interferometer. APPLIED OPTICS 1986; 25:4332. [PMID: 18235787 DOI: 10.1364/ao.25.004332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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Son JY, Farmer WM. Analytical evaluation of PSI response. APPLIED OPTICS 1986; 25:2806. [PMID: 18231564 DOI: 10.1364/ao.25.002806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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