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.

Species and habitat-dependent accumulation and biomagnification of brominated flame retardants and PBDE metabolites

Choo, Gyojin,Lee, In-Seok,Oh, Jeong-Eun Elsevier 2019 Journal of hazardous materials Vol.371 No.-

<P><B>Abstract</B></P> <P>The occurrence, species- and habitat-dependent distribution of brominated flame retardants (BFRs) and PBDE metabolites comprising 27 polybrominated diphenyl ethers (PBDEs), 3 hexabromocyclododecanes (HBCDs), tetrabromobisphenol A (TBBPA), 17 methoxylated (MeO-) BDEs, and 8 hydroxylated (OH-) BDEs were determined in marine environments (sediment and seawater) and 20 biota species in food web in the southern part of Korea. The concentration of HBCDs was statistically higher in both pelagic (5.73–60.1 ng/g lipid weight [lw]) and demersal fish (2.45–31.3 ng/g lw), whereas a higher level of OH-BDEs was observed in benthic invertebrates (2.48–40.7 ng/g lw), suggesting different composition of BFRs and PBDE metabolites between species. The concentrations of TBBPA and MeO-BDEs were significantly higher in pelagic fish (1.31–11.3, 6.15–61.5 ng/g lw) than in demersal fish (not detected [N.D.]–4.45, 0.956–8.52 ng/g lw) and benthic invertebrates (N.D.–8.11, 0.182–4.65 ng/g lw), reflecting a dependence on habitat. Additionally, analogue distribution of PBDEs in pelagic fish was similar to that in seawater, whereas the distribution in demersal fish and benthic invertebrates was similar to the distribution in sediment. The bioconcentration factor (BCF) and trophic magnification factor (TMF) of α-HBCD, some of PBDEs, and 6-MeO-BDE47 were up to 5000 and 1, respectively, suggesting strong bioaccumulation and biomagnification.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Different distributions of BFRs and PBDE metabolites were observed according to the species and habitat of biota. </LI> <LI> The level of HBCDs was higher in pelagic and demersal fish, whereas OH-BDE level was higher in benthic invertebrates. </LI> <LI> The concentrations of MeO-BDEs and TBBPA in pelagic fish were higher than those in demersal fish and benthic invertebrates. </LI> <LI> α-HBCD, some congeners of PBDEs (BDE49, 71, 100), and 6-MeO-BDE47 were strongly biomagnified and bioaccumulated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

PBDEs and their structural analogues in marine environments: Fate and expected formation mechanisms compared with diverse environments

Choo, Gyojin,Kim, Da-Hye,Kim, Un-Jung,Lee, In-Seok,Oh, Jeong-Eun Elsevier 2018 Journal of hazardous materials Vol.343 No.-

<P><B>Abstract</B></P> <P>The concentrations and relative distributions of 27 polybrominated diphenyl ethers (PBDEs) and 17 methoxylated (MeO-) and 8 hydroxylated (OH-) BDEs were determined in marine environments including sediments, bivalves, and seawater along the southern coast of South Korea to understand their fates and possible formation mechanisms. The relative and substituent distributions of the PBDEs and their structural analogues varied according to the characteristics of the media. PBDEs were dominant in marine sediments and seawater, whereas MeO-BDEs made the highest contributions in bivalves. Similar patterns were previously identified in inland environments in Korea, except in river water where OH-BDEs were dominant. The natural formation of structural analogues might be the main mechanism in marine, as <I>ortho</I>-substituted naturally occurring MeO- and OH-BDEs were dominant in all media and seemed to be more produced than in inland environments. In addition, the higher concentrations of meta-substituted MeO-BDEs nearshore than offshore was observed. This is the first study comparing marine (near- and offshore) and inland to understand the differences in their fate and possible formation mechanisms in each environmental conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The distributions of PBDEs and their structural analogues were compared between marine (near- and offshore) and inland. </LI> <LI> PBDEs dominated in abiotic media, whereas MeO-BDEs were dominant in biota. </LI> <LI> Natural formation might be the main mechanism for PBDE structural analogues in marine and was highly occurred than in inland. </LI> <LI> The higher contributions of meta-MeO-BDEs were observed in inland and nearshore than offshore. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

국가종합전자조달시스템의 이용확산과 조달행정 발전방안

오정석,이낙영 충남대학교 기초과학연구소 2003 忠南科學硏究誌 Vol.30 No.1

The Government e-Procurement System(GePS) is a comprehensive system to be established for public procurement administration usage, which permits the administration to be more effective in its work. GePS enables all public organizations to conduct the procurement process electronically, and thus makes the procurement administration much more effective and transparent. A single window containing all procurement information allows enterprises a great of convenience in their commerce activities. Additionally, the development of an electronic network means that all information related to the procurement business may be jointly used. This joint usage of information and easy document exchange between public organization and private companies reduces remarkably the amount of paperwork and documentation needed for a contract. The purpose of this paper is to find a way of expanding the usage of GePS by analyzing statistics prepared in early in its operations. The plans of political development for the Procurement administration as the operator of GePS in the time of government digitalization are presented in this paper.

Hand & rotary root canal instrument의 근관내 삭제 형태에 관한 전자현미경적 비교

오태석,박정원 大韓齒科保存學會 1998 Restorative Dentistry & Endodontics Vol.23 No.1

In the case of CAD/CAM ceramic inlay restorations, if isthmus width is widened too much, it may cause fracture of remaining tooth structure or loss of bonding at the luting interface because of excessive displacement of buccal of lingual cusps under occlusal loads. So to clarify the criterior of widening isthmus width, this study was designed to test the tensile bond strength and bond failure mode between dentin and ceramic cemented with luting composite resin cements. Cylindrical ceramic blocks(Vita Cerec Mark Ⅱ, d=4mn) were bonded to buccal dentin of 40 freshly extracted third molars with 4 luting composite resin cements(group1:Scotchbond Resin Cement/Scotchbond Multi-Purpose, group2:Duolink Resin Cement/All-Bond 2, group3:Bistite Resin Cement/Ceramics Primer, and group4:Superbond C&B). Tensile bond test was dond under universal testing machind using bonding and muasuring alignment blocks(￠ilo & Um, 1992). After immersion of fractured samples into 1% methylene blue for 24 fours, failure mode was analysed under stereomicroscope and SEM. Results:The tensile bond strength of goup 1, 2 & 4 was 13.97±2.90 MPa, 16.49±3.90 MPa and 16.17±4.32 MPa. respectively. There was no statistical differences(p>0.05). But, group 3 showed significantly lower bond strengnth(5.98±1.17 MPa, p<0.05). In almost all samples, adhesive fractures between dentin and resin ccments were observed. But, in group 1, 2 & 4 as bond strength increased, cohesive fracture within resincement was observed simultaneously. And, in group 3, as bond strength decreased, cohesive fracture between hybrid layer and composite resin cement was also observed. Cohesive fracture within dentin and porcelain adhesive fracture were not observed. In conclusion, although adhesive cements were used in CAD/CAM fabricated ceramic inlay restorations, the conservative priciples of cavity preparation must be obligated.

조직 확장기를 이용한 안면부 재건

오 경,정영하,김정태,김석권 대한미용성형외과학회 1997 Archives of Aesthetic Plastic Surgery Vol.3 No.1

In the past years skin grafts, local flaps and free flaps have been used in reconstructing skin or sift tissue defects and deformities of the face where primary closure is not feasible. A number of local flaps have been used for reconstruction of facial defects and deformities, but the size of a defect that could be treated in such a way was restricted and the donor site deformity was another problem of local flaps. Introduction of the tissue expansion technique has made it possible to cover even wider defects with neighboring skin and advantageous in facial reconstruction in that such defects can be resurfaced with skin of similar color, texture and thickness, a match superior to that of skin obtained elsewhere. We used tissue expanders in reconstructing defects and deformities of the face(post-burn scar ; 17cases, post-traumatic scar ; 7cases, congenital nevus ; 3cases, total 27cases) from Mar. 1990 to Sep. 1996. We used or croissant type tissue expander for the reconstruction of small-sized scar on medial cheek and to use rectangular type expander for large-sized scar on lateral cheek. Ports are placed under the scar or scalp. Expansion period ranged from 28days to 97days (mean 7weeks) and overinflation (mean 170%) was done. And Various methods are used for prevention of complication. We have made anchoring sutures of the remained capsule to the underlying periosteum for prevention of ectropion. We have got satisfactory results from that aesthetically and functionally, so report the results with a review of the current literature.

체육교육의 존재지향적 전개를 위한 기본적 탐색

오정석,김달우 師範大學 體育硏究所 1993 서울大學校 體育硏究所論集 Vol.14 No.2

The purpose of this paper is to examine the current status of physical education so that its objectives and nature may be ascertained and an appropriate course of development might be found. According to Erich Fromme, the approach to life can be seen as either possession oriented or existence oriented. In the possession oriented mode even knowledge is seen as something which is possessed. Current physical education is based on the possession oriented approach. It is imperative then that physical education must reorient itself so that it might serve the existence oriented mode of being and facilitate the quest for the significance of this mode of being. As to the question of “Why is the recovery of this knowledge of existence inseperable from physical education?”. The reason lies in the fact that existence is experiential and physical education is the most fundamental of all forms of education when it comes to the experience of human existence. Physical activity is not an act of observation but requires direct participation. The thing which enhances this experience is the imagination. The imagination helps us take the experience of human movement to a higher level. The point which physical education must convey is that which the individucal personally discovers through direct experience. Therefore the essence of physical education can be summed up as “realization through movement.” In distinguishing the approach of physical education from other approaches, the following three points are salient; 1. Physical education emphasizes experiential physical activity. 2. The significance of expression is emphasized. 3. A physical way of thinking is emphasized. Be offerring the experience of physical activity to students, the beauty of human existence can be discovered and the significance of that kind of lifestyle might be realized. physical education then, in the midst of a diminishing sense of humanity seen in our mechanized civilization, will play a vital role in rediscovering this humanity and restoring its original from to mankind.

서울 지역 여자대학교 집단에서 월경전기 증후군 및 월경전 불쾌기분장애의 유병율

정범석,이철,이지현,서민경,한오수,김창윤 大韓神經精神醫學會 2001 신경정신의학 Vol.40 No.4

연구목적 : 가임기 여성의 75%가 하나 이상의 월경전기 증상을 경험하며, 일상생활에 지장을 주는 경우도 3∼8%에 이르지만 한국 여성을 대상으로 한 월경전기 증후군(Premenstrual syndrome : PMS)및 월경전 불쾌기분장애((Premenstrual dysphoric disorder : PMDD)에 대한 역학 조사는 부족한 실정이다. 따라서 본 자들은 한국에서의 유병율, 증상의 양태 및 삶에 미치는 정도 등의 역학 조사를 통해 월경전 불쾌기분장애에 대한 올바른 정보를 제공하고 관련 임상 연구의 기초자료로 활용하고자 본 연구르 시행하였다. 방 법 : 6개의 서울 소재 4년제 여자대학교에서 무작위 군집표본 추출로 선택된 4개 학교의1∼3학년 학생 중 무작위 군집표본추출을 통해 선택된 1419명을 대상으로 하였다. DSM-IV진단기준을 근거로 저자들이 제작한 6점 척도의 설문지가 사용되었으며, 난포기에 비해 황체기에 75%이상 악화된 경우 증상이 있다고 판정할 경우의 월경전 불쾌기분장애의 유병율을 조사하였다. 월경전 불쾌기분장애 집단과 증상은 있으나 진단기준에 부합되지 않는 월경전기 증후군 집단으로 나누어 증상 양태, 식습관 변화, 생활에 미치는 영향 정도 등을 비교하였다. 결 과 : 부적절한 자료 198명(13.9%), 주요 신체 혹은 정신질환을 앓은 경우 등 선정 배제 기준에 속하는 경우 348명(24.5%)을 제외한 873명이 최종 분석되었다. 873명 중 월경전 불쾌기분장애의 유병율은 5.0%이었으며, 월경전기 증후군의 유병율은 83.3%이었다. 가장 흔한 증상은 월경전기 증후군 집단의 경우 신체증상(54.6%)이었고, 월경전 불쾌기분장애 집단의 경우 '지속적으로 짜증난다'(95.5%)이었다. 월경전 불쾌기분장애 집단의 88.6%에서 증상 때문에 한 달에 1∼2회 이상 일이나 공부에 지장이 초래되었다. 결 론 : 한국 여자대학생 집단이 경험하는 월경전 불쾌기분장애의 유병율과 증상 양상은 외국과 비슷하다. 아울러 월경전 불쾌기분장애 집단은 월경전기 증후군 집단에 비해 기분 증상이 더 흔하고 심하는 점에서 월경전 불쾌기분장애는 월경전기 증후권과 구별되는 하나의 질환 상태임을 시사한다. Objects : More than 75% of women have been reported to experience premenstrual symptoms and three to eight percent of them suffer from premenstrual dysphoric disorder(PMDD). But little is known about prevalence of premenstrual syndrome(PMS) and PMDD and PMS in Korean women who sttended universities at the time of survey. Methods : One thousand four hundred and nineteen subjects were randomly selected with cluster sampling methods among four women's university in Seoul. We measured the severity of premenstrual symptoms using six-point rating scale developed by the authors on the basis of the research criteria for PMDD in DSM-IV. Premenstrual worsening of symptoms was defined as increase in symptom scores of more than 75% from follicular to luteal phase score. And also, we compared characteristic symptoms, eating behaviors, and functional impairments between PMS and PMDD. Results : After excluding inadequate data according to our exclusion criteria, 873 of 1419 subjects(61.5%) were included in the estimation of the prevalence of PMS and PMDD. Each prevalence rate of PMS and PMDD was found to be 83.3% and 5.0% on the basis of 75% change method respectively. The most frequent symptom was physical symptoms such as headache or breast tenderness(56.4%) in PMS and 'felt irritable'(9.5%) in PMDD. Of the 44 subjects with PMDD, 39(88.6%) reported to have experienced the impairment in work or school at least once per month because of premenstrual symptoms. Conclusions : Our results indicate that prevalence and symptoms of PMDD in Korean university women are similar to those in western culture. The finding that mood symptoms were more frequent and severe in PMDD than in PMS implies that the former may be a disordered condition to be distinguished from the latter physiologic one.

육총용류의 면역증진 효과 비교 연구

오정석,함인혜,김형민,최호영 대한본초학회 2005 大韓本草學會誌 Vol.20 No.1

Objectives : This study was to investigate the anti-immobility effect of Cistanche deserticolae Herba (CD) and Cistanche salsae Herba (CS) Methods : Forced swimming test (FST) and changes of blood biochemical parameters related to fatigue, glucose (Glc), blood urea nitrogen (BUN), latic dehydrogenase (LDH) aspartate aminotransferase (AST), alanine aminotransferase (ALT) and total protein (TP) were investigated. Results : CD and CS were orally administered to mice for 7 days. After 7 days, the immobility time was significantly decreased in the CD-treated group and CS-treated group in comparison with the control group. The contents of serum AST were significantly decreased and contents of Glc and LDH were decreased in CD-administration group . However, it had no effect on the elevation of TP level, whereas, the contents of GIc were increased and the contents of ALT, BUN and LDH in the blood serum were decreased in the CS (0.01 g/kg/day)-fed group. Conclusions : These results suggest that Cistanche herba, CD and CS may have immune-enhancing effect.

CITIS 지원 문서관리 시스템 설계에 대한 연구

정석찬,조장혁,김상균,류병우,오원식,김정훈,최익성 한국경영과학회 1998 한국경영과학회 학술대회논문집 Vol.- No.1

본 연구에서는 일반 기업간에 전자상거래를 지원하기 위한 CITIS(Contractor Integrated Technical Information Service)를 지원하는 문서관리 시스템을 개발하기 위하여, MIL-STD-974의 요구사항과 일반적으로 상용화되어 있는 문서관리 시스템의 기능적 요구 사항을 검토하였다. 이것을 바탕으로 기업간 기술정보 교환의 근간이 될 수 있는 CITIS를 지원하는 문서관리 시스템의 기능을 도출하였다. 조달자인 정부와 공급자인 기업간의 계약에 의한 기술정보 서비스로서의 CITIS 요구사항을 기본으로 하되, 이를 CALS 환경에서 기술정보 서비스에 적용할 수 있도록 개발 요구 사항을 재정립하였다. 일반적인 문서관리 시스템의 기능은 현재 시장에서 상용화되어 있는 PDM 제품의 기능을 분석하여 참조하였다. 한편 CITIS 지원을 위한 부품 구조 관리 기능과 연계를 위하여 문서와 부품 간의 관계가 고려되었으며, 작업흐름관리와의 연동을 위해서는 전자 결재판 개념의 패킷 객체가 고안되었다. 소프트웨어 설계 방법론으로는 객체지향형 소프트웨어 개발 방법론을 채택하여 CITIS 구현을 위한 객체 모델, 동적 모델, 기능 모델을 작성하였다. 소프트웨어 개발 언어는 인터넷 웹 브라우저를 근간으로 활용될 수 있도록 Java를 이용하며, 다른 응용분야와의 손쉬운 통합을 위하여 CORBA 개념을 도입하였다.