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Superconducting MgB2 Wire Drawing Considering Anisotropic Hardening Behavior and Hydrostatic Effect
Young‑Seok Oh,Ho Won Lee,Kook‑Chae Chung,Duck‑Young Hwang,Seong‑Hoon Kang,Jeong Whan Yoon 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7
Numerical modeling was conducted to investigate the deformation behavior of powder mixture during multi-pass drawingprocesses for multi-filamentary MgB2wire. A modified Drucker-Prager Cap (DPC) model with an elliptical cap surface usingthe new material characterization method was developed to capture the anisotropic hardening behavior and hydrostatic effectof the powder mixture. A number of uniaxial die compaction, cold isostatic pressing, diametrical compression, and uniaxialcompression tests were conducted using different powder densities to characterize the modified DPC model. A commercialfinite element software ABAQUS with a user subroutine was used to simulate the drawing of the MgB2wire. The densityand area fraction of the powder mixture during the wire-drawing process were verified with experimental results. The differencein packing density at the inner and outer filaments of the MgB2wire was successfully captured by simulation. Inaddition, the effect of the initial packing density on the superconducting properties of MgB2wire was numerically studied. It is shown that the increase in the superconducting area, which results from a high initial packing density, should be moreeffective compared to the increase in the grain connectivity in enhancing the critical current properties for the MgB2wirewhen the final packing density is saturated after a number of drawing processes.
Chae, Won-Seok,Moon, Jung-Nim,Kim, Kang-Jin 한국분석과학회 1995 분석과학 Vol.8 No.4
The charge transfer rate in polypyrrole(PPy) electropolymerized within poly(acrylonitrile-co-butadiene)(PAB) was compared with that in PPy deposited Pt electrodes by using cyclic voltammetry, chronoamperometry, and chronopotentiometry in acetonitrile. For both electrodes anodic and cathodic peak currents were proportional to scan rates below 100 mV/sec, but to square root of scan rates beyond 200 mV/sec. The apparent diffusion coefficient of $ClO{_4}^-$ in the PPy/PAB composite is estimated to be 1.6 times larger than that in PPy. The PPy films composited within PAB layer showed higher anodic and cathodic currents and possessed faster charging-discharging process and larger capacity.
Chae, Sangmin,Yi, Ahra,Park, Cheolmin,Chang, Won Seok,Lee, Hyun Hwi,Choi, Jiyeon,Kim, Hyo Jung American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.29
<P>We report femtosecond infrared laser-induced selective tailoring of carrier transport as well as surface morphology on a conducting polymer blend thin film. Maximal 2.4 times enhancement on vertical current transport in poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester, was achieved by this irradiation. The laser irradiation induced a photo expansion without deteriorating its molecular structure and the film morphology could be customized in the micron scale by adjusting the laser writing parameters. In the photoexpanded region, the face-on populations were about 2.2 times larger in comparison with the pristine region, which was a major contributor to the enhanced carrier transport.</P>
Won-Seok Chae,Chun-Nam Cha,Chang-Yeul Yoo,Suk Kim,Hu-Jang Lee 한국예방수의학회 2018 예방수의학회지 Vol.42 No.1
Highly pathogenic avian influenza virus (HPAIV) damages vital organs and tissues, frequently leading to death in birds, and causes serious economic losses in the poultry industry. In addition, HPAIV can infect humans and other mammals, often with fatal outcomes. In this study, the virucidal efficacy of Clean-Zone??, which contains citric acid, malic acid and phosphoric acid, against avian influenza virus (AIV, H9N2) was investigated. Virucidal efficacy was determined by examining the viability of AIV after contact with the disinfectant in the allantoic membrane of chicken embryos. The disinfectant and AIV were reacted under hard water (HW) and organic matter suspension (OM) condition. AIV was inactivated with 200- and 50-fold dilutions of the disinfectant under HW and OM conditions, respectively. As the disinfectant, Clean-Zone??, has a virucidal efficacy against AIV, it can be used to prevent the spread of animal viral diseases.
Electrochemical and Spectrofluorometric Behaviors of Eu(III) Complexes in Aqueous Solution
Chae Won-Seok,Kim Kang-Jin Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.12
Eu(Ⅲ) exhibits one electron-transfer reduction at E$_{1/2}$ =-0.617 V vs. Ag/AgCl and the hypersensitive peak at 618 nm corresponding to $^5D_0$ ${\leftrightarro}$ $^7F_2$ transition in 0.10 M LiClO$_4$ aqueous solutions. Upon the addition of carboxylate or sulfonate anions to the Eu(Ⅲ) aqueous solutions, the reduction potential shifts negatively and the reduction current decreases because of the complex formation between Eu(Ⅲ) ions and the anions. However, for the case of carboxylate anion (acetate or propionate) the shift of reduction peak potential and the emission intensity at 618 nm are greater. The results are interpreted in terms of the differences in the formation constants and the hypersensitivity.
Septated Extradural Arachnoid Cyst in Thoracolumbar Spine Causing Myelopathy
Chae, Ki-Hwan,Kim, Seok-Won,Shin, Ho The Korean Neurosurgical Society 2006 Journal of Korean neurosurgical society Vol.40 No.5
Spinal extradural arachnoid cyst is uncommon and rarely cause neural compression. We report a rare case of severe cord compression due to septated spinal extradural arachnoid cyst. A 35-year-old woman has developed back pain 3 months prior to her visit, but recently motor weakness and urinary incontinence occurred. Magnetic resonance images showed an extradural cyst posterior to the cord, which was flattened and displaced from T12 to L2. Urgent decompressive laminectomy and cyst removal was performed. Histopathological examination confirmed that cyst wall was formed by nonspecific fibrous connective tissue without a single-cell layer of inner arachnoid lining. Motor weakness and voiding difficulty were recovered completely after operation.
Won-Seok Chae,Eun-Kee Park,Chang-Yeul Yoo,Chun-Nam Cha,Lutfiye Tutkun,Song-Ee Son,Suk Kim,Hu-Jang Lee 한국예방수의학회 2016 예방수의학회지 Vol.40 No.4
The coronavirus porcine epidemic diarrhea virus (PEDV) infects the cells lining the small intestine of a pig and, causes porcine epidemic diarrhea (PED). Owing to its highly infectious nature, PEDV has a substantial economic burden, which results in significant morbidity and mortality in piglets. In this study, the virucidal efficacy of a powder disinfectant containing a phosphate compound against PEDV was investigated. Virucidal efficacy was assessed as the infectivity of PEDV toward Vero cells after exposure of the virus to the disinfectant. PEDV was exposed to the disinfectant in the presence of either hard water (HW) or an organic matter suspension (OM). In the HW condition, PEDV was inactivated by 4-fold dilution of the disinfectant. In the presence of OM, the disinfectant showed virucidal activity with a 2-fold dilution. As the disinfectant possessed virucidal activity against PEDV, it should be an effective reagent for limiting the spread of animal viral diseases.
Chae, Hansong,Han, Seung Jung,Kim, Su-Young,Ki, Chang-Seok,Huh, Hee Jae,Yong, Dongeun,Koh, Won-Jung,Shin, Sung Jae American Society for Microbiology 2017 Journal of clinical microbiology Vol.55 No.9
<P>The prevalence of tuberculosis continues to be high, and nontuberculous mycobacterial (NTM) infection has also emerged worldwide. Moreover, differential and accurate identification of mycobacteria to the species or subspecies level is an unmet clinical need. Here, we developed a one-step multiplex PCR assay using whole-genome analysis and bioinformatics to identify novel molecular targets. The aims of this assay were to (i) discriminate between the Mycobacterium tuberculosis complex (MTBC) and NTM using rv0577 or RD750, (ii) differentiate M. tuberculosis (M. tuberculosis) from MTBC using RD9, (iii) selectively identify the widespread M. tuberculosis Beijing genotype by targeting mtbk_20680, and (iv) simultaneously detect five clinically important NTM (M. avium, M. intracellulare, M. abscessus, M. massiliense, and M. kansasii) by targeting IS1311, DT1, mass_3210, and mkan_rs12360. An initial evaluation of the multiplex PCR assay using reference strains demonstrated 100% specificity for the targeted Mycobacterium species. Analytical sensitivity ranged from 1 to 10 pg for extracted DNA and was 10(3) and 10(4) CFU for pure cultures and nonhomogenized artificial sputum cultures, respectively, of the targeted species. The accuracy of the multiplex PCR assay was further evaluated using 55 reference strains and 94 mycobacterial clinical isolates. Spoligotyping, multilocus sequence analysis, and a commercial real-time PCR assay were employed as standard assays to evaluate the multiplex PCR assay with clinical M. tuberculosis and NTM isolates. The PCR assay displayed 100% identification agreement with the standard assays. Our multiplex PCR assay is a simple, convenient, and reliable technique for differential identification of MTBC, M. tuberculosis, M. tuberculosis Beijing genotype, and major NTM species.</P>