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외부보강된 밀봉 상태가 다른 Bi-2223테이프의 가압 LN<sub>2</sub>하에서 임계전류의 굽힘변형률 의존성
신형섭,박정수,Shin, Hyung-Seop,Dizon, John Ryan C,Park, Jeong-Soo,Rolley, Bonifacio 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.6
The critical current degradation behaviors of multifilamentary Bi-2223 superconducting tapes under pressurized liquid nitrogen were investigated using a r-shaped sample holder which gives a series of bending strains to tape. Three kinds of externally-reinforced Bi-2223 tapes with different hermeticity were used as samples. The tape with the thicker reinforcement layer had a better bending strain tolerance of $I_c$, but when the bending strain was calculated at the outermost filament, the $I_c$ degradation behavior became identical. For all samples, $I_{c0}$ decreased with the increase of applied pressure, but the $I_c$ degradation behavior with bending strain at each pressure level was similar. Furthermore, after depressurization from 1 MPa to atmospheric pressure, $I_c$ was completely recovered to its initial values. When the samples were warmed up to room temperature after pressurization tests, the ballooning damage occurred at lower bending strain regions. The region where ballooning was observed was identical to the one where the significant $I_c$ degradation occurred.
탄화규소에 구형입자의 정적압입 및 충격시 부하속도의 영향
신형섭,Shin, Hyung-Seop 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.12
In order to study the relationship between static and cynamic behaviors of silion caride, both quasi-static indentaiton and impact experiments of spherical particle have been conducted. The difference inmaterial behavior when using the two mehtods suggests a loading rate difference in the damate pattrern and fracture strength of silicon carbide. This investigation showed some difference in damage pattern according to particla property, especially inthe case of particle impact. There was no differences in deformation behaviors according to the loading rate when the crater profiles were compared with each other at the same contact radius. From the result of residual strength evaluation, it was found that the strength degradation began at the initiation of ring crack and its behavior was colsely related to morphologies of the damage developed which was also dependent upon the extent of deformation atthe loaidng point. In the case of static indentation, there didnot exist the particle property effects onthe strength degradation behavior.
마그네슘합금(AZ31B) 판재의 마찰교반 점용접시 접합특성에 미치는 툴 속도의 영향
신형섭,정윤철,최광,Shin, Hyung-Seop,Jung, Yoon-Chul,Choi, Kwang 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.2
In this study, the friction stir spot welding (FSSW) of Mg alloy sheets has been tried using an apparatus devised with a CNC milling machine to give the precise control of joining condition including tool speed. The probe tool used is made of hard metal and composed of cylindrical shoulder and pin parts. The variation of morphologies formed after the friction stir spot welding depending on the plunge speed of the tool were investigated at each rpm of tool. The history of the temperature distribution and the vertical load induced during the spot welding with friction time were measured by using an Infrared Thermal Imager (THERMA CAMTM SC2000) and a loadcell located below the specimen fixture, respectively. Tensile-shear tests were also performed to evaluate the fracture load of welded specimens. In order to characterize the friction stir spot welding of Mg alloy sheets, the variation of the fracture load was discussed on micrographic observations, temperature distribution during the FSSW according to the plunge speeds of tool.
신형섭(Hyung-seop Shin),오상엽(Sang-Yeob Oh),서창민(Chang-Min Suh) 한국자동차공학회 2002 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
The use of laminated plates, in which safety performance superior to monolithic ones is warranted, is growing very rapidly, Many advantages including high-performance and low-weight structures of laminated constructions make the use of laminated plates in automobile, architectural glazing and aerospace and aeronautical field, In this work, impact induced damage in glass/PMMA laminated plates with an interlayer of epoxy resin was investigated by an instrumented long bar impact under a ball-on-ring(BOR) bending fixture, In order to increase the damage tolerance of laminated circular plates, various geometric and material parameters are investigated to determine their effects in maximizing the absorbed impact energy, Parameters include the thickness of each layer and dissimilar materials of laminated plates. The measured impact force profiles explained well the damage behavior induced in laminated circular plates.<br/>
신형섭(Hyung-Seop Shin),최호연(Ho-Yeon Choi) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.6
본 연구에서는 CNC선반을 사용하여 다양한 공구재질과 절삭속도에서 벌크금속유리(BMG)의 절삭 특성을 평가하였다. 선반가공시 Zr-기 BMG의 표면거칠기와 칩 형상을 관찰하여 가공조건에 따른 절삭력과 공구툴 마모 등 절삭 특성을 비교·검토하였다. 직경 8 mm Zr50Cu40Al10 BMG시험편의 절삭에는 네 종류의 절삭공구를 사용하였다. 가공후 BMG 시험편의 표면거칠기를 측정하였고, 표면거칠기에 미치는 공구 회전속도의 영향을 조사하였다. 회전속도가 빠를수록 낮은 표면거칠기를 나타내었고, 공구 재질의 영향도 크게 나타났다. 칩 형상의 관찰 결과, 산화를 일으키지 않은 BMG 칩은 단열 전단띠 발생과 함께 나선형상의 형태를 나타내지만, 산화를 일으킨 칩은 국부적으로 용융과 함께 칩들이 뭉치는 현상을 나타내었다. BMG시험편을 가공하는 동안 발생한 절삭력은 TiN-WC에서 가장 큰 값을 나타내고, PCD가 그 다음, Cermet툴에서 가장 작은 값을 나타내었다. In this study, the cutting characteristics of bulk metallic glass (BMG) cut using a computer numerically controlled (CNC) lathe were investigated for different insert tool materials and cutting speeds. The surface roughness, chip morphology, cutting forces, and tool wear during turning of Zr50Cu40Al10 BMG alloy were examined. Four kinds of tool materials were used to cut an 8-mm-diameter BMG. The examination of the surface roughnesses of the BMG specimens machined at each cutting speed showed that the surface roughness became better as the cutting speed increased, and the tool materials also influenced the surface roughness. The chip morphology investigations showed that the unoxidized BMG chips had serrated curled chips with adiabatic shear bands, while the oxidized chips exhibited local melting and tangling rather than the usual spiral-shaped chips. The cutting force induced during machining of the Zr-based BMG was the largest for the TiN-WC tool, followed by the polycrystalline diamond (PCD) tool. The cermet tool exerted the smallest cutting force.
터빈엔진 파편 방벽설계를 위한 고강도 섬유의 기계적 특성 평가
신형섭(Hyung-Seop Shin),D. C. Erlich,D. A. Shockey 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3
Shielding barrier concepts to protect critical aircraft components from uncontained engine debris are currently developing. Fragment impact tests confirmed that barriers made from high strength polymer fabrics, especially Zylon, could prevent penetration into the cabin. In this study, some quasi-static tests such as tensile and transverse load to measure mechanical properties of yams were carried out.