• Proceedings of the Korean Vacuum Society Conference
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• 2009.08a
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• pp.201-201
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• 2009

• Journal of the Microelectronics and Packaging Society
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• v.18 no.2
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• pp.11-15
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• 2011

Heat transfer equation is first reviewed and then governing equation of moisture diffusion. Analogy scheme is applied to analysis the moisture absorption problem of polymers. It make possible to numerically analyze the diffusion problem for single medium by using commercial finite element code if it is under the isothermal loading condition. It is extended to special multimaterial system by introducing pressure ratio function, whose moisture characteristics of materials are proportional to temperature only. The weight changes of silicon-nonconductive-polymer joint model due to moisture absorption is measured and been very close to the numerical results as for single media with boundary condition with zero concentration, but yields numerical errors as for multisystem media.

• Journal of Welding and Joining
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• v.29 no.1
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• pp.14-19
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• 2011

• Proceedings of the Korean Nutrition Society Conference
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• 2002.11a
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• pp.108-108
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• 2002

• Journal of the Korean Society for Railway
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• v.17 no.6
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• pp.391-396
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• 2014

In this study, the strength of magnesium-GFRP/epoxy single-lap bonded joints are experimentally evaluated with different end shapes. In order to achieve this, four different single-lap joints with different end shapes are fabricated and the failure load is measured under tensile loading tests. From the test results, the single-lap joint with a square end exhibits the lowest failure load while the single-lap joint with reverse tapering and a spew fillet has the highest stress values. It has 11.1% higher failure strength than the single-lap joint with a square end.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.86.2-86.2
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• 2012

산화금속은 높은 결정성, quantum size effect, 높은 투과도, 대기중의 안정도 등과 같은 탁월한 성질들로 인하여 오늘날 실리콘의 대체물로서 많은 연구가 보고되고 있다. 이러한 금속산화물의 크기와 모양을 조절하며 대량 생산하기 위한 합성방법으로 가수분해, 금속양이온 응축법과 같은 다양한 수용액상 방법이 연구되고 있다. 하지만 2차원 단일 층에 나노물질을 정렬하고 전기적 접합을 형성하는 것이 매우 어렵다는 점 때문에 나노물질을 기판 위에 자유롭게 성장시키는 방법에 대해서는 아직 많이 보고 되어있지 않다. 본 연구에서 저온의 수용액에서 1차원의 나노막대가 2차원의 스피넬 구조 위에 heteroepotaxial 접합을 이루며 성장시키는 방법을 이용하였다. P-n접합 형성을 위하여 (0001)방향으로 배향된 n-type ZnO 나노막대를 (111)방향의 p-type Co3O4 나노플레이트 위에 성장시킨 구조를 제작하였으며 이를 바탕으로 다이오드소자를 제작하여 ideal factor, turn-on voltage, rectifying ratio등의 전기적 특성을 평가하였다.

• Journal of Welding and Joining
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• v.14 no.2
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• pp.79-89
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• 1996

일정진폭하중과 과대하중비 2.5의 단일 인장과대하중에 의한 4140강 용접부 의 피로균열성장거동을 실온과 -45.deg.C의 저온에서 피로시험과 파면관찰을 통하여 고찰하였다. 이때, 용접부 미시조직의 영향을 평가하기 위해 모재(parent metal), 열영향부(as-welded HAZ), 열처리된 열영향부(PWHT HAZ)로 나누어 응력비 0과 0.5로 CT시험편을 이용하여 피로시험을 실시하였다. 피로균열성장거동은 재료의 미시조직과 온도변화보다는 응력비에 크게 영향을 받았으며, 단일 과대하중에 의한 피로균열성장 지연효과가 모든 재료에서 상당히 크게 나타났다. 전자현미경에 의한 피로파면 관찰 결과, 실온에서는 연성의 스트라이에이숀과 -45.deg.C에서는 의벽개파면과 같은 피로 균열성장거동을 나타내고 있다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.6 s.360
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• pp.64-70
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• 2007

This paper presents a novel unified DC offset cancellation and I/Q regeneration for five-port junction based direct receivers. It utilizes the symmetry characteristics of the single-frequency continuous-wave (CW) signal, making it possible that the proposed method can be used regardless of carrier phase offset. The proposed method eliminates the additional DC offset cancellation and reduces the I/Q regeneration parameter estimation time. Since the proposed method employs a single-frequency CW signal independent of the modulation scheme, five-port junction based direct receivers can be used for the demodulation of orthogonal frequency-division multiplexing and continuous phase modulation as well as phase shift-keying.

• Journal of Korean Society of Steel Construction
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• v.27 no.1
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• pp.1-12
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• 2015

Well-designed bolted connections can exhibit excellent ductile behavior through bearing mechanism until the occurrence of bolt shear rupture. The ultimate strength analysis of eccentric bolted connections is an economical and mechanistic approach which uses such ductility. However, the bolt load-deformation relationship, which forms basis of the current practice, is based on very limited combinations of bolt and steel materials. The primary objective of this study was to establish the general bolt force-deformation relationship based on systematic single-bolt bearing connection tests. The test results showed that the projected area of the bolt hole and the strength and thickness of the plate to be connected are the main factors affecting the force-deformation relationship. The results of this study can be used for the instantaneous center of rotation method (ICRM) to achieve more accurate analysis and economical design of a variety of group-bolted connections subjected to eccentric shear.

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.546-551
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• 2010

In this paper, the strain distribution of the bond layer has been compared with the experimental data and analyzed according to the different mesh refinements and element types. The mesh density was changed along the longitudinal direction of adherend, the longitudinal direction of overlapped region, the vertical direction of adherend, the vertical direction of adhesive and the width direction of the joint. In addition, the effect of the different types of element was evaluated using soild, shell and plane strain element. The geometric nonlinear analysis was performed to consider the large deformation of the joint. From the numerical result, at least 2 elements were needed to achieve a reliable result as the solid element used. In case of shell element, the peel strain at x/c=1 showed 22.8% error compared with the experiment but the shear strain showed a good agreement with the experiment within 1.67% error.