• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.4
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• pp.287-296
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• 1996

A mathematical model for the dynamic analysis of the riser system is developed to investigate the effect of internal flow on the free vibration of marine riser system which includes a steady flow inside the pipe. A semi-analytical method using series expansion is employed to derive Eigenvalue problem to facilitate the evaluation of the system frequencies, and its validity is given through the comparison of the solutions with the conventional method using system matrices. The algorithm is implemented to develop computer programs for the estimation of the system frequency. The investigations of the effect of internal flow on system frequency are performed according to the change of parameters such as top tension, internal flow velocity, and so on. It is found that the effect of internal flow can be controlled by the increase of top tension. However, careful consideration has to be given in the design point, particularly for the long riser.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.166-171
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• 1993

절삭공구에의한 절삭가공은 오늘날 가장 보편화된 가공기술중의 하나이다. 그런데, 최근들어 각종 첨단산업의발전과 함께 초정밀 부품제작이 필수선결 조건으로 부상하고 있으며, 이에대한 해결방안중의 하나로 초정밀가공 기 술로 크게 대두되고 있다. 최근 컴퓨터 기술의 발달에 따라 구조해석분야의 해석방법론의 개발 및 보완에 힘입어 Klemecki(1973)에 의해유한요소법을 이용한 Chip생성기구 해석에 관한 연구가수행되었으며, Stevenson(1983) 등에의해단열조 건하에서 변형률과 온도 상태에서의 Chip형상, 잔류응결-변형율에 대한 연구가 이루어졌다. 본 연구에서는 유한요소법을 이용하여 미소절삭기구를 모델링하고, 절삭인자규명을 중심으로 응력-변형률 해석을 실시함으로써, 미소절삭시의 Chip 생성기구 및 전단면 생성 원리, 공구와 Chip간의 마찰기구의 고찰을 통해기본 Mechanism 이해와 적절한 절삭유한요소모델 제시의 기초자료로 삼고자 한다. 특히 본 보고서에서는 미소 절삭기구의 적정한 Constitutive Deformation Law 마찰계수 등 주요절삭인자변경에 따른 미소절삭기구 해석에 주안점을 두어 연구한 결과를 기술하였다.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.147-156
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• 2001

본 연구에서는 칩 캡슐화 성형 공정 중의 패들 변형을 해석하기 위한 방법론이 연구되었다. 헬레쇼오 근사 모델에 근거한 유한요소법이 칩 캐비티에서의 유동 해석을 위해 사용되었다. 리드 프레임 상의 구멍을 통한 통과 유동해석을 위한 근사모델이 제안되었다. 본 연구에서 제시된 해석모델에 의해 계산된 값과 실험 값은 잘 일치하였다. 유동해석을 통하여 리드프레임과 패들에 의해 경계를 이루고 있는 상, 하 캐비티간의 압력차가 계산되었다. 최종적으로 패들 변형이 압력차 계산 값을 이용하여 계산되게 된다.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.584-589
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• 1998

범용 전산유체 해석코드인 CFX 4.1을 사용하여 철재격납용기 표면을 전열면으로 이용하는 피동격납용기냉각계통에 대한 열전달 현상해석을 수행하였다. 철재격납용기 내부와 외부 채널에서 발생하는 열전달 현상을 모사하기 위하여 액막의 유동 및 온도계산 모델을 범용 전산유체해석코드인 CFX4.1에 적용하여 철재격납용기 내.외부의 표면을 흐르는 액막의 높이, 액막내 온도분포, 철재격납용기 내.외부의 온도, 유속 및 부피분율 등을 계산하는 복합 열전달 해석 방법론을 개발하였다. 해석결과는 향후 실험 둥을 통한 검증이 필요하나 피동형 격납용기템각계통에서 발생하는 물리적 현상들의 복합적인 거동 분석에 사용될 수 있는 것으로 평가되었다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.247-250
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• 2010

최근 많은 건축가들이 파라메트릭 디자인 도구에 관심을 가지고 형태에 대한 다양한 실험을 하고 있는 것과는 달리, 구조 엔지니어들은 이에 적절하게 대응하지 못하고 있다. 현재 파라메트릭 모델과 구조해석 프로그램사이의 자료교환을 가능하게 하는 인터페이스가 없는 것이 주된 원인이다. 따라서 구조 엔지니어들도 자유롭게 파라메트릭 방법론의 장점을 활용한 모델을 생성하고, 그것을 구조해석에 바로 사용할 수 있도록 하는 일이 오늘날 구조계가 당면한 과제이다. 본 연구에서는 파라메트릭 모델로부터 구조해석 모델을 자동으로 생성하는 인터페이스의 실무 적용가능성을 살펴보기 위하여, 파라메트릭 디자인 도구의 특성과 확장성을 검토하고, 라이노를 기반으로 하는 구조해석 모델 생성 플러그인을 개발하였다.

• Korean Journal of Construction Engineering and Management
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• v.8 no.5
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• pp.71-79
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• 2007

It is common that the analysis of VE/LCC is performed in design phase of quay wall structures. The analysis is mainly executed based on experience and engineering sense of expert considering the selection of construction method, construction and maintenance cost. Recently there are increasing demands on the analysis that includes uncertainty and vulnerability of input parameters, for this purpose, fuzzy reliability based probabilistic VE/LCC analysis model for quay wall structures is suggested. In VE/LCC analysis for quay wall structures, the application of probabilistic analysis method give very similar results compare with those of deterministic analysis method. It is anticipated that the methodology proposed in this paper can also be utilized in the design and maintenance phase of other facilities where decision making is made for the probabilistic life cycle cost and value analysis.

• The Journal of Korean Philosophical History
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• no.39
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• pp.7-27
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• 2013

T'oegye placed great emphasis on the cultivation of quiet-sitting. His idea of quiet-sitting, like Zhu Xi's, had various therapeutic effects as well. This can be highlighted as a real-life practice and a diverse application of the "abiding by Gyong" that he stressed; it is also associated with the treatment of physical diseases, composure in the mind, the benefits of reading, meditation in solitude, and many other areas. And We can easily infer that T'oegye would have set some premises before referring to Hualin Simbang. First, he would have been wary of quiet-sitting being the goal of cultivation: Too much obsession with and emphasis on Toinsul would actually obstruct the practice of "abiding by Gyong" and mislead one's effort for the "preservation and nourishment of the mind" and "reflection and examination." T'oegye would have probably used the physical and breathing exercises in Hualyin Simbang mainly as a reference to treat his physical illnesses. Also, his Toinsul would have been employed independently and partially as a sort of supplementary practice-without being used in parallel with quiet-sitting as one of the methods to achieve reverent seriousness.

• Journal of the Korean Geotechnical Society
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• v.38 no.11
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• pp.19-30
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• 2022

Developing a fragility curve for the levee requires calculating the probability of failure according to the water level for each failure mode. Since probabilistic analysis requires iterative analysis to account for variability in geotechnical parameters, the fragility curve development inevitably requires many iterative calculations. Therefore, approximate probabilistic analysis techniques are usually applied to reduce the amount of calculation in developing the levee fragility curve. However, their accuracy has not been determined clearly. This study calculated the failure probability of slope and piping failure mode for an actual levee through probabilistic methods, such as FOSM, PEM, and MCS. Then, the fragility curve of the levee according to the water level was developed. The results of the approximate methods: FOSM and PEM, were compared with those of MCS to evaluate the applicability to the fragility curve for slope and piping failure mode.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.6
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• pp.55-64
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• 2001

Industrial machines are sometimes exposed to the danger of earthquake. In the design of a mechanical system, this factor should be accounted for from the viewpoint of reliability to analyze a complex nonlinear structure system under random excitation is proposed. First, the actual random excitation, such as earthquake, is approximated to the corresponding Gaussian process for the statistical analysis. The modal equations of overall system are expanded sequentially. Then, the perturbed equations are synthesized into the overall system and solved in probabilistic way. Several statistical properties of a random process that are of interest in random vibration are evaluated in each substructure. Comparing with the results of the numerical simulation proved the efficiency of the proposed method.

• Journal of the Korean Wood Science and Technology
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• v.32 no.5
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• pp.66-74
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• 2004

Fire performance is the important criterion for evaluating of safety of wood structures which exposed to the standard fire condition. Endurance time and time-to-failure are used as the criteria for fire performance in many countries. Reliability analysis about wood floor system which exposed to fire was carried out as preliminary research for reliability-based design on fire. Analyses were conducted by two methods, numerical analysis method and deterministic method.. They didn't show the difference between two methods. The reliability of floor exposed to fire showed strong dependence on the coefficient of variation of member and did not be influenced by the strength or load of member.