• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1872-1873
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• 2004

보이드, 이물, 돌기등 고부자 절연체 내의 결함은 이곳에 전계가 가해질 때, 국부적 전계집중을 유발하며, 절연체 내의 미소 방전을 일으킨다. 이 때 발생한 미소 방전에 의해 보이드 표면의 고분자 물질은 기계적, 화학적 열화를 일으키며, 이에 따라 전기적 트리를 형성하게 된다. 이러한 트리는 결국 절연체의 절연파괴로 진전되므로, 고분자 물질을 절연물로 사용하는 전력기기의 경우에는 신뢰성에 큰 문제를 유발한다. 따라서, 이러한 방전(부분방전)이 일어날 때 생기는 전기적 신호를 검출하여, 절연물의 신회성을 평가하는 것은 매우 중요하다. 본 논문에서는 이러한 미소방전이 일으키는 방전의 파형이 트리의 진전에 따라 어떻게 변화하는지에 대해 연구하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2391-2397
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• 1993

The distribution of fatigue crack growth rate is influenced by the measuring interval and methods of calculation of crack growth rate. The purpose of this paper is to suggest a method for the evaluation of crack growth rate distribution without the influence. The constant ${\Delta}P$ test and the constant .DELTA.K test are executed by using the CT specimen. The measuring interval of (${\Delta}a$/W=0.0067~0.014) crack length is not affected by methods of the calculation of the fatigue crack growth rate is suggested.

• Proceedings of the KAIS Fall Conference
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• 2012.05a
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• pp.336-339
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• 2012

본 연구는 여성 결장암 환자의 암 진전도에 영향을 미치는 요인을 규명하고자 시도하였다. 자료수집은 2012년 1월 23일부터 2012년 2월 23일까지 서울에 소재한 종합병원 외과에 내원한 결장암 환자 227명을 선정하여 설문조사를 하였다. 연구결과는 첫째, 이전의 결장암 검사여부는 암 검사를 하지 않은 여성은 distant는 61.7%로 localized인 여성은 36.7% 보다 유의하게 높았다($X^2$=26.41, p<.05). 둘째, 교육과 암검진력은 양의 상관관계를 보였다(r=0.27, p<.01). 셋째, 연령이 암 진전도를 23.8%, 과거 결장암 검진여부는 7.5%, 스트레스여부는 4.1%로 각각 설명하였다. 이러한 결과를 토대로 결장암 위험요인에 노출되어 있는 여성들의 결장암 발생을 예방하기 위해서는 조기검진에 대한 적극적인 홍보과 교육이 필요하다고 본다.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.235-240
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• 2003

Methods to predict fatigue crack growth are compared in a quantitative manner for crack growth test data of 2024-T351 aluminum alloy under narrow and wide band random loading. In order to account for the effect of load ratio, crack closure model, Hater's equation and NASGRO's equation have been employed. Load interaction effect under random loading has been considered by crack closure model, Willenborg's model and Wheeler's model. The prediction method using the measured crack opening results provides the best result among the prediction methods discussed for narrow and wide band random loading data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1785-1792
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• 2003

Methods to predict fatigue crack growth are compared in a quantitative manner for crack growth test data of 2024- T351 aluninum alloy under narrow and wide band random loading. In order to account for the effect of load ratio, crack closure model, Hater's equation and NASGRO's equation have been employed. Load interaction effect under random loading has been considered by crack closure model, Willenborg's model and Wheeler's model. The prediction method using the measured crack opening results provides the best result among the prediction methods discussed for narrow and wide band random loading data.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.286-291
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• 2001

Applications of bonded dissimilar materials such as IC package, ceramic/metal and resin/metal bonded joints, are very increasing in various industry fields. It is very important to analyze the thermal stress and stress singularity at interface edges in bonded joints of dissimilar materials. In orer to understand the package crack emanating from the edge of Die pad and Resin, fracture mechanics of bonded dissimilar materials and material properties are obtained. In this paper, the thermal stress and its singularity index for the IC package were analyzed using 2-dimensional elastic boundary element method. Crack propagation angle and path by thermal stress were numerically simulated with boundary element method.

• The Korean Journal of Financial Management
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• v.15 no.1
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• pp.41-71
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• 1998

글로벌화가 진전된 산업의 경우에는 세계산업 내지 세계시장 요인이 현지시장 내지 현지산업 요인보다 더 중요한 ADR과 원주 수익률의 결정요인으로 실증된다. 원주의 움직임에 대해서는 대체로 현지산업, 현지시장 요인, 세계시장 요인, 세계산업 요인순으로 설명력이 높게 나타난 반면, 글로벌화가 진전된 산업의 기업 원주에 대해서는 세계시장 또는 세계산업 요인, 현지시장 또는 현지산업 요인 순으로 설명력이 높다. ADR의 움직임은 대체로 세계시장 요인, 현지산업 요인, 현지시장 요인, 환율 요인, 세계산업 요인, 미국산업 요인, 미국시장 요인 순으로 설명되는 반면, 글로벌화가 진전된 산업의 경우에는 세계시장 또는 세계산업 요인, 환율 요인, 현지산업 요인, 현지시장 요인 순으로 설명력이 높다. 한편, 원주와 ADR간에 수익률과 변동성은 모두 상호관련성이 높고, 원주 수익률을 설명하는 요인과 동일 외국기업의 ADR을 설명하는 요인은 대체로 일치한다.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.15-22
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• 2008

Applications of bonded dissimilar materials such as integrated circuit(IC) packages, ceramics/metal and resin/metal bonded joints, are very increasing in various industry fields. It is very important to analyze the thermal stress and stress singularity at interface edge in bonded joints of dissimilar materials. In order to investigate the IC package crack propagating from the edge of die pad and resin, the fracture parameters of bonded dissimilar materials and material properties are obtained. In this paper, the thermal stress and its singularity index for the IC package were analyzed using 2-dimensional elastic boundary element method(BEM). From these results, crack propagation direction and path by thermal stress in the IC package were numerically simulated with boundary element method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.125-134
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• 1989

Pseudo-random load waves for fatigue testing were generated by personal computer simulation and preliminary study was performed on the growth behavior of surface fatigue crack under random ladings. The closure behavior and growth rates of surface fatigue crack were significantly influenced by the characteristics of random waves. It was also found that the growth rates of surface fatigue crack under random loadings could not be always described by the effective stress intensity factor based on the concept of crack closure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1691-1699
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• 1992

The experimental results of fatigue crack propagation under constant amplitude loading show that intra-and inter-specimen variability exist. In this paper, a stochastic model for the estimation of mean and variance of crack propagation life is presented To take into account the intra-specimen variability, the material resistance against crack propagation is treated as an 1-dimensional spatial stochastic process, i. e. random field, varying along the propagation path. For the inter-specimen variability, C in paris equation is assumed to be a random variable. Compared with experimental results reported, the present method well estimate the variation in fatigue crack propagation life. And it is confirmed that the thicker the specimen thickness is, the less the variation of propagation life is.