• 한국재난정보학회 논문집
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• 제10권1호
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• pp.123-140
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• 2014

회전쉘의 정적문제 및 동적문제에 대해서 선점법에 의한 공간영역의 이산화에 대한 유효성을 비교 검토하였고, 정식화에 있어서 이산화 후의 연립방정식 및 시간에 관한 연립상미분방정식의 계수행렬에 대한 영향을 검토하였다. 수치해석법에는 동적특성의 문제를 간단하고 효과적인 방법을 위하여 선점법을 제안하였으며, 수치해석예로서 평균2승잔차법과의 비교검토로 고정도의 해석을 위한 정확성을 검증하였다.

• 대한조선학회논문집
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• 제54권3호
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• pp.267-273
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• 2017

Pressure hulls of submerged structures are generally designed as circular cylinders, spheres or cones with form of axisymmetric shell of revolution to withstand the high external pressure of deep ocean. The compressive buckling (implosion) due to hydrostatic pressure is the main concern of structural design of pressure hull and many design codes are provided for it. It is well-known that the buckling behavior of thin shell of revolution is very sensitive to the initial geometric imperfections introduced during the construction process of cutting and welding. Hence, the theoretical solutions for thin shells with perfect geometry often provide much higher buckling pressures than the measured data in tests or real structures and more precise structural analysis techniques are prerequisite for the safe design of pressure hulls. So this paper dealt with various buckling pressure estimation techniques for unstiffened circular cylinder under hydrostatic pressure conditions. The empirical design equations, eigenvalue analysis technique for critical pressure and collapse behaviors of thin cylindrical shells by the incremental nonlinear FE analysis were applied. Finally all the obtained results were compared with those of the pressure chamber test for the aluminium models. The pros and cons of each techniques were discussed and the most rational approach for the implosion of circular cylinder was recommended.

• 대한조선학회지
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• 제22권1호
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• pp.21-30
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• 1985

This paper deals whth the buckling as well as postbuckling analysis of axisymmertric shells taking the initial deflection effects into account. Incremental equilibrium equations, based on the principle of virtual work, were derived by the finite element method, the successive step-by-step Newton-Raphson iterative technique was adopted. To define the transition pattern of postbuckling behavior from the prebuckling state more accurately, a simple solution method was developed, i.e. the critical load was calculated by the load extrapolation method with the determinant of tangent stiffness matrix and the equilibrium configuration in the immediate postbuckling stage was obtained by perturbation scheme and eigenvalue analysis. Degenerated isoparametric shell elements were used to analyse the axisymmetric shell of revolution. And by the method developed in this paper, the computer program applicable to the nonlinear analysis of both thin and moderately thick shells was constructed. To verify the capabilities and accuracies of the present solution method, the computed results were compared with the results of analytical solutions. These results coincided fairly well in both the small deflection and large deflection ranges. Various numerical analyses were done to show the effect of initial deflection and shape of shells on buckling load and postbuckling behavior. Futhermore, corrected directions of applied loads at every increment steps were used to determine the actual effects of large deflection in non-conservative load systems such as hydrostatic pressure load. The following conclusions can be obtained. (1) The method described in this paper was found to be both economic and effective in calculating buckling load and postbuckling behavior of shell structure. (2) Buckling and postbuckling behavior of spherical caps is critically dependent upon their geometric configuration, i.e. the shape of spherical cap and quantities of the initial deflection. (3) In the analysis of large deflection problems of shells by the incremental method, corrections of the applied load directions are needed at every incremental step to compensate the follower force effects.

• 한국소음진동공학회논문집
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• 제13권8호
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• pp.626-636
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• 2003

The beat distribution property of the King Seong-deok Divine Bell is investigated by experiment and analysis. The beat map method is proposed to explain the beat distribution property on the circumference of the bell. For the analytical investigation, an analytical model of the vibration beat is derived on a slightly asymmetric shell of revolution by using the modal expansion method. In the analytical method, the beat map can be drawn only if the modal parameters of the bell are obtained. The analytical beat model is applied to draw the beat map of the King Seong-deok Divine Bell. The validity of the analytical method is verified by comparing the analytical beat maps with the experimental results. This paper proposes a visualization method of the beat and theoretically identifies the reason why the clear and unclear beats repeat periodically along the circumference of the bell and how the striking position influences the beat distribution property.

• Structural Engineering and Mechanics
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• 제6권7호
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• pp.785-800
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• 1998

This paper deals with the nonlinear finite element analysis of fibre-reinforced plastic poles. Based on the principle of stationary potential energy and Novozhilov's derivations of nonlinear strains, the formulations for the geometric nonlinear analysis of general shells are derived. The formulations are applied to the fibre-reinforced plastic poles which are treated as conical shells. A semi-analytical finite element model based on the theory of shell of revolution is developed. Several aspects of the implementation of the geometric nonlinear analysis are discussed. Examples are presented to show the applicability of the nonlinear analysis to the post-buckling and large deformation of fibre-reinforced plastic poles.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.139-140
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• 2010

콘크리트 격납구조물의 돔과 링빔은 서로 접합된 상태로 단면력 분포에 있어 상호 영향을 미치기 때문에 연계 해석이 필요하다. 이 연구에서는 축대칭 회전쉘의 막이론을 적용하여 본설계시의 유한요소해석에 앞서 돔과 링빔의 초기 형상이나 링빔의 프리스트레스 수준을 효율적으로 결정할 수 있는 기법을 제안하였다.

• 대한기계학회논문집
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• 제9권4호
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• pp.487-496
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• 1985

회전하는 축대칭 얇은 셸구조물의 진동 특성을 유한요소법에 의하여 해석하였다. 2개의 절점을 가진 Conical Frustrm 형태의 축대칭 요소를 사용하였으며 원주방향의 변위는 Fourier Series로 분해하여서 방정식의 수를 상당히 줄일 수 있었다. Sanders-Koiter의 셸이론을 사용하였으며 진 동 모우드는 회전의 영향을 설명하기 위하여 대칭 및 비대칭 모우드를 모두 고려하였다. Coriolis 행렬을 포함하는 운동방정식에서 고유 진동수를 계산하기 위해서 질량, 강성 및 Coriolis 행렬로 이루어지는 Hermitian 행렬의 Sturm Sequence Property를 이용하였으며, 좁은 밴드를 갖는 대형 행렬에 알맞는 Determinant Search 방법을 확장하여 고유진동수 및 벡터를 구하였다. 원통형 셸에 대하여 정지한 경우 계산한 고유진동수를 실험치 및 이론치와 비교한 결과 잘 일치됨을 알 수 있었다. 여러 가지 회전 속도에 대해서 얻어진 고유진동스를 이론치와 비교한 결과 잘 일치 됨을 알 수 있어\ulcorner며 회전의 영향으로 traveling wave진동의 현상이 나타남을 알 수 있었다.

• 스마트미디어저널
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• 제9권4호
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• pp.109-117
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• 2020

최근 디지털 트윈은 제4차 산업혁명의 도래와 더불어 물리적 시스템과 사이버 시스템을 연계하고 통합하는 중요한 기술로 부각되고 있다. 본 논문에서는 에너지 분야의 전력기자재 디지털 트윈화를 위하여 필요한 디지털 트윈화의 절차에 따른 요구사항을 분석하고, 또한 이러한 디지털 트윈을 구축하기 위한 핵심 구성요소라 할 수 있는 인더스트리 4.0 기반의 AAS(Asset Administration Shell)의 개념과 기능 및 특성 분석을 기반으로 구체적인 설계를 하였다. 하지만, 아직까지는 국내·외 적으로 디지털 트윈구현을 위한 공통된 플랫폼이나 실증 모델에 관해서는 많은 연구가 이루어 지지 못하고 있는 상황이므로, 본 논문에서는 에너지 분야의 전력기자재 디지털 트윈화를 염두에 두고 디지털 트윈 플랫폼 구축하는데 필요한 핵심 요구사항을 분석하고, 실제 디지털 트윈을 구축함에 있어서 핵심적 역할을 수행하게 될 AAS의 기능과 특성을 기반으로 실제로 전력기자재를 대상으로한 AAS의 설계를 함으로써 향후 스마트 에너지 디지털 트윈을 구축 및 실증을 위한 절차와 구체적 기능들을 제시하고자 하였다.

• 한국실내디자인학회논문집
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• 제14권6호
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• pp.95-102
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• 2005

The purpose of this study was to analyze the ambiguity of the boundary through the composition of section. The building means the compose of the inside space by physical shell. Inside space that has boundary factors like floor, wall, roof and column is surrounded outside space. The factors which compose the boundary was expressed by architects as various analysis, but it has changed as changing of paradigm and information revolution. The inside space and outside space were connected through the system arrangement, so various space could construct by an aspect of relation. The history of architecture was written as the establishment of in-out space by architectural boundary factors, but the space could not divide definitely, composed complex structure, could experience various recognition. The existing study which is focused on Ambiguity of the Boundary is just focused on contemporary architecture. Ambiguity of the Boundary is developed by using glass. The transparency of glass removed the boundary of space, so it can be created free wall, continuity of view. It was Influenced the boundary of the sight and changed the expression of boundary between the space. This study is to analyze the change of boundary awareness and find the ambiguity of boundary in the section.

• Tribology and Lubricants
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• 제29권2호
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• pp.105-110
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• 2013

Refrigeration and air-conditioning compressors used in home appliances, including refrigerators and air conditioners, are typically hermetic-type reciprocating compressors. Because the shell is sealed by welding, it should be designed to have a semi-permanent life. The energy consumption of a hermetic-type reciprocating compressor is low, but because it operates continuously to maintain a constant temperature inside the refrigerator, it has a certain base load. In this type of compressor, the driving motor operates at a high speed (about 3,000 - 3,600 rpm), which causes valve damage, friction, wear, and high-frequency noise. Many studies have been conducted to solve these problems. To enhance the reliability and efficiency of the reciprocating compressor, the design conditions and operating environment of journal bearings should be considered. Dynamic behavior analysis should be carried out in terms of the discharge pressure. The results showed that the load (discharge pressure) increases in the forward lookup zone and decreases in the backward lookup zone. When the revolution speed is increased, the maximum load decreases in the region where the maximum load operates.