• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.383-385
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• 2008

본 논문은 헤드스페이스 추출에 의한 절연유중 가스분석 결과의 정확도 향상을 위해 여러 가지 인자들을 고려하였으며, 진단결과의 신뢰도 향상을 위해 표준절연유를 직접 제조하여 이에 의한 교정을 통해 분석법의 진단 신뢰도 향상을 제고하였다. 기존의 추출율이 높은 토플러 추출방법에 대한 결과와 Headspace 분석법에 의한 결과를 각각 비교하고, Headspace 추출법에 의한 결과의 정확도 향상을 위해 여러가지 인자들을 고려하였다. 향후 최적 조건을 수립하여 수은에 의한 인체 유해성이 없는 Headspace 분석법으로의 전환을 모색하고자 한다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.228-233
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• 2004

The characteristics of the probability distribution for mechanical properties, e.g. tensile strength, reduction of area ana elongation, for STS304 stainless steel in elevated temperature were investigated from tensile test performed by constant cross head speea controls with 1mm/min, Recently, in order to clarify the strengthening mechanisms at high temperature, a new scheme to improve high temperature mechanical properties is desired. Therefore, the test ,technique development of high temperature creep behaviors for this material is very important. In this paper, the creep praperties and creep life prediction by Larson-Miller parameter method for STS304 stainless steel to be used for other high temperature components were presented at the elevated temperatures of 600, 650 and $700^{\circ}C$.

• Journal of Ocean Engineering and Technology
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• v.18 no.2
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• pp.64-69
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• 2004

The characteristics of the probability distribution for mechanical properties, e.g. tensile strength, reduction of area, and elongation, for STS304 stainless steel in elevated temperature are investigated. Tensile test is performed by constant crosshead speed controls with 1mm/min. The probability distribution function of measured mechanical properties seems to follow $\alpha$ 3-parameter Weibull, and shows a slight dependence on the temperature. When the temperature is raised, the shape parameter a is increased, but both the scale parameter $\beta$ and location parameter v are decreased.

• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.58-65
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• 1999

The effect of specimen thickness on fatigue crack growth rate was studied. The objective of the present study is to investigate the effect of specimen thickness on the fatigue crack growth behavior at various stress intensity factor ranges and also the variation of material restance to fatigue crack growth. The fatigue crack growth resistance was treated as a spatial stochastic process, which varies randomly on the crack path, Compact tension specimens with a LT orientation for structural steel were used. All testing was done at a constant stress intensity level. The experimental data were analyzed for the size effect to determine the Weibull distributions of the material resistance.

• Construction Engineering and Management
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• v.2 no.1 s.5
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• pp.8-11
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• 2001

요즘 매스컴에서 건설회사 도산 및 부실 등에 대한 보도가 많아지고 있다. 98년 말부터 우려해 오던 건설산업 구조조정이 한창 진행 중에 있으며, 2000년 7월말 현재 100대 건설사중 37개사가 법정관리, 화의, 워크아웃 상태이며, 이후 대형건설업체의 계속되는 부도 등 부실화로 인한 퇴출이 더욱 가속되고 있는 상황이다. 이렇게 건설 회사들이 부실화가 된 원인을 살펴보면, 공사 발주물량은 97년 대비 70{\%}대에 머물고 있는 반면 건설업체 수는 오히려 $60{\%} 정도 증가해 업체별 평균 수주액이 급감하였고, 이에 따라 업체들의 과당 출혈 경쟁으로 수익성이 악화되고 말았다. 그러나 이러한 건설업의 어려운 환경에서도 고려개발(주)는 2000년 당기순이익 176억원 등 ‘89년 이후 12년 동안 순익을 내고 있으며, IMF가 한창이던 98년부터 2000년까지 약 1조2천억원의 수주고를 달성하였다. 또한 2000년 부채비율 $146{\%}$, 자기자본비율 $41{\%}$, 자기자본순이익율 $14{\%}$로 선진건설업체 수준의 재무비율을 확보하여 경영평가 1위를 차지하고 있다. 이러한 원인을 고려개발(주)는 건설산업의 구조조정에서 살아남을 수 있는 해결책은 정보화라고 판단하여 지난 ’95년부터 꾸준히 사내 정보화 정착에 전력하고 있다.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.140-148
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• 2006

본 논문에서는 선진 제품의 신뢰성 수준과 국산 제품의 신뢰성 수준 비교 결과를 정량적으로 표시하기 위한 신뢰성지수를 개발하여 제안하였다 본 연구에서 제안한 신뢰성지수는 가장 우수한 제품의 신뢰성수준과 비교하고자 하는 제품의 신뢰성 수준을 점수화한 신뢰성점수의 비로서 나타낸다. 이 때 신뢰성점수는 제품 초기 특성값 산포, 환경시험 후의 특성변화율, 제품 설계 여유도, 제품 수명 또는 고장률의 4가지 항목을 고려하여 미리 정한 점수 산출 기준을 통하여 산출한다. 제안한 신뢰성지수의 적용방법에 대한 이해를 돕기 위하여 구체적인 적용례도 함께 제시하였다.

• Journal of Power System Engineering
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• v.6 no.4
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• pp.49-55
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• 2002

In this paper, the elevated temperature tensile properties and short-time creep rupture characteristics were investigated for the friction welded joints of dissimilar materials, Cu-1%Cr-0.5%Zr and STS316L. The joining tests on Cu-1%Cr-0.5%Zr/STS316L by friction welding were performed, and optimum joining conditions of the friction welded joints were determined. The characteristics of the elevated temperature tensile strength, hardness, fractographs were examined, and the creep rupture characteristics for the optimum welded joints were investigated under uniaxal static load at 300, 400 and $500^{\circ}C$.

• Proceedings of the Korea Information Processing Society Conference
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• 2024.05a
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• pp.167-168
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• 2024

본 연구에서는 물리계층 보안을 위한 키 길이를 IoT 무선 채널 상태에 따라 조정하는 링크 적응 방법을 제안한다. 시뮬레이션 결과에 따르면 제안 방식은 종래 방식 대비 평균 78.52% 개선된 처리율과 약 2배 개선된 보안성을 보인다.

• Land and Housing Review
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• v.2 no.2
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• pp.125-135
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• 2011

Automobile-oriented urban transport system, continued from the past in Korea, is giving rise to inefficiency and social costs in transport sector. With revitalizing usage of bicycle, human-powered transport mode, it is possible to enhance sustainable green growth, improvement of the city-competitiveness, and the quality of life. In this study, the possibility of bicycle usage promotion in Korean cities is examined at 7 points of views. As a result, though the bicycle usage is low now, we figured that there are many positive signs to increase bicycle usage in Korea. Also, we draw a diverse key policies for building green urban transport system that bicycle have a most important role on transport system. So policies to promote bicycle usage are reviewed to analyze on bicycle-oriented 5 cities, in which have high bicycle mode share. By this review, this study could draw 41 key effective policies to 3 aspects (bicycle infrastructure, safety and promotion, and policy sustainability). In addition to, importance of 21 key effective policies about bicycle infrastructure is suggested as considering city's characteristics.

• Journal of the Korean Magnetics Society
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• v.6 no.5
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• pp.317-322
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• 1996

Thin films of Fe-Zr-N were fabricated by rf magnetron reactive sputtering method. The saturation magnetization and coercivity as functions of annealing temperature and partial pressure of nitrogen gas, effective permeability at high frequencies, and thermal stability were investigated. Magnetic softness was exhibited in the composition range of $Fe_{72-78}Zr_{7-10}N_{15-18}$ which was boundary between polycrystalline and amorphous structure. These films exhibited magnetic softness with saturation magentic flux density of 1.55 T and effective permeability of about 3000 at 1 MHz. These films also exhibited thermal stability by sustaining effective permeability of 2500 or above as the temperature was raised to $550^{\circ}C$. It is asswned that good magnetic softness is obtained because grain growth of $\alpha-Fe$ is prohibited due to the precipitation of ZrN nanocrystals. The grain sizes of $\alpha-Fe$ films were $40~50\AA$ and the grain sizes of ZrN nanocrystals were $10~15\AA$.