• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.111-117
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• 1999

섬유강화 복합재료의 섬유와 수지까지 세부적으로 모델링이 가능한 Direct Numerical Simulation을 통해서 Boron/Aluminum 섬유강화 복합재료의 탄성계수들을 구해 보았다. 수치실험에서는 복합재료를 직교이방성 물질로 가정하였고, 특정 체적에 대한 평균치를 이용해서 물성치를 구하였으며, 혼합법칙에 의해서 구한 값 및 대표체적요소(Representative Volume Element)를 사용해서 구한 값들과 비교하였다. 혼합법칙의 경우, 섬유방향 인장계수(E₁)을 제외한 나머지 물성치들에 대해서는 상당한 차이를 나타내며, 이는 혼합법칙 유도과정에서 가정한 기본가정들이 적절하지 않기 때문이라는 것을 수치실험(Numerical Experiment)을 통해 알 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.731-740
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• 1995

The objective of this paper is to develop defect assessment technology for integrity evaluation of CANDU pressure tubes. In fracture mechanics analysis, three-dimensional and two-dimensional (line-spring model) finite element analyses were performed to obtain the stress intensity factor for axial and circumferential surface cracks. In leak before break (LBB) analysis, heat transfer analyses for through-wall cracks were performed by considering the cooling effect and the LBB application time was computed. It was shown that the analytical results obtained in this study provide less-conservative but accurate solution for defect assessment of CANDU pressure tubes.

• Journal of the Korean Society of Safety
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• v.6 no.4
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• pp.73-80
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• 1991

Interest in fracture of structure has increased significantly over the past decade. New approaches to analyze structural performance have been accompanied by the development of test methods to characterize material behavior in a manner compatible with the analysis. Several test methods have been developed as a results of advances in fracture mechanics, for example, $K_{IC}$ , $J_{IC}$, R-curve tearing instability and CTOD approaches. Among the rest, fracture toughness $K_{IC}$ and $J_{IC}$ can be used as an effective design criterion in fracture mechanics. Generally, the determintion of $J_{IC}$ was performed according to ASTM E 813 or JSME S 001 and $K_{IC}$ was performed according to ASTM E 399. In this study, the test method for $K_{IC}$ and $J_{IC}$ were discussed.scussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.1
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• pp.172-179
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• 1996

For mechanical systems operating at high tempertature, thermal fatigue phenomenon has been recognized as a major cause of mechanical component failures. To evaluate cumulative fatigue damage as a conesquence of thermal fatugue on real time, the stress tranfer function(Green's function) approach is popularly used. The objective of this paper is to investigate the effect of thermophsical properties on the stress tranfer function. For this purpose a modified Green's function approach considering temperature-dependent thermophysical properties is proposed. Two case studies were performed and the proposed approach agrees well with full finite element analysis.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.175-185
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• 1999

Acoustic emission(AE) measurement was carried out to evaluate the fracture behavior of high tension steel. Fracture toughness $K_{AE}$ could be determined reasonably by using the load value corresponding to an abrupt change of the accumulated AE counts AE emitted from the test specimens. AE characteristics of the base metal, the weld metal and the heat-affected zone could be distinguished using a constant value b which represented the AE amplitude distribution, Consequently the structure integrity can be evaluated by variation of the constant b at the load level. In addition it was found that AE signals due to crack growth have high amplitude but low rise time and duration.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06b
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• pp.307-309
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• 2006

움직이는 오브젝트(Object)를 추출하기 위한 배경 제거(Background Subtraction) 단계는 실시간 감시시스템(Real-time Surveillance System)에서 중요한 과정 중에 하나이다. 배경 제거를 효과적으로 진행하기 위한 배경을 모델링, 배경 유지 보수 방법이 존재하는데, 효율성이 높은 방법으로 적응적 가우시안 혼합 배경 모델링(Adaptive Gaussian Mixture Background Modeling)이 제시되고 있다. 본 논문에서는 이기법을 바탕으로 하여 이러한 실시간 배경 모델링 시스템을 구현하려 하고, 중앙 처리 장치(CPU)가 아닌 그래픽 처리 장치(Graphic Processing Units : GPU)를 사용하여 보다 향상된 방범을 구현함으로서 관련사항을 제안하려 한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.128-129
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• 2007

Cr-Al-N, Cr-Si-N 그리고 Cr-Al-Si-N 코팅막을 WC-Co 모재위에 AIP법과 DC 마그네트론 스퍼터링 법을 결합한 하이브리드 시스템을 이용하여 합성하였으며, Si함량에 따른 Cr-Al-Si-N 코팅막의 미세구조, 기계적 특성과 마찰 거동에 관해 비교 연구하였다. Cr-Si-N(${\sim}35GPa$)과 Cr-Al-Si-N(${\sim}55GPa$) 코팅막의 경도값은 CrN(${\sim}23GPa$)과 Cr-Al-N(${\sim}25GPa$) 코팅막과 비교하여 각각 증가하였고, CrN(${\sim}0.50$)과 Cr-Al-N(${\sim}0.84$)의 평균 마찰계수는 Si 함량이 9 at.% 일때, Cr-Si-N(${\sim}0.30$)과 Cr-Al-Si-N(${\sim}0.57$)으로 각각 감소하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.49-54
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• 2005

This paper describes the result of structure analysis and load test of body structure. The purpose of the analysis and test is to evaluate an safety which body structure shall be considered fully sufficient rigidity so as to satisfy proper system function under maximum load and operating condition. Material of body structure applied an aluminum alloy. Body structure consist of side frame, under frame, roof frame, end frame. Both FEM analysis and load test are based on 'Performance Test Standard for Electrical Multiple Unit, noticed by Ministry of Construction & Transportation, in 2000' and reference code is JIS E 7105. The test results have been very safety and stable fer design load conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.622-626
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• 2005

The Residual stress is stress at the inside of materials after plastic deformation. Certainly, this residual stress have an effect on fatigue life. Therefore, it is very important that understanding residual stress at the inside of materials. But in case of U-shaped Pipe that it is dealt with a mailer in this paper, distribution of residual stress is very complicated and exactly become unknown caused by difficulty of measurement. Then, in this paper, we are evaluated residual stress at in the inside of materials by finite clement method program and verified validity by test.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.1214-1217
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• 2007

대부분의 기관들은 악의적인 행위들을 포착하거나 시스템과 데이터를 보호하고 사고에 대응하기 위한 시도들을 지원하기 위해 몇 가지 형태의 네트워크 기반 보안솔루션을 사용하고 있다. 하지만 기존 네트워크 레벨 보안의 한계로 인하여 시스템 상에서 일어나는 행위를 제어하기 위한 차세대 보안솔루션으로 보안운영체제를 도입하고 있다. 최근에는 전자금융거래법 등의 세칙에 의해 정보처리 시스템 내의 정보의 유출, 변조 및 파괴 등을 보호하는 것은 물론 세부 작업 내역의 로깅에 대한 요구가 지속적으로 증가하고 있다. 이에 본 논문에서는 보안레이블에 의한 시스템 보안 강화 기술을 소개하고 강제적 접근 제어 결과에 의해 생성되는 보안 로그에 대한 구체적인 관리 전략을 제시한다.