• Journal of the korean Society of Automotive Engineers
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• v.18 no.4
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• pp.67-87
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• 1996

본 연구에서는 차체의 충돌해석 및 모델링을 위하여 판/쉘 요소의 자동생성 모듈을 개발하고 재료의 변형특성 모델링 모듈 및 접촉처리 모듈을 개발하였다. 충돌해석용 전처리기능으로는 평면, 실린더 곡면, B-스플라인 곡면 및 블렌딩 (blending) 곡면상에서의 사각형 요소망 자동생성 기법과 프로그램을 개발하였다. 또한 차체를 구성하고 있는 여러가지 재료들의 변형거동을 모델링하여 개발중인 충돌해석전용프로그램인 Autocrash의 모듈로서 완성하였다. 이들은 변형률속도의 영향이 고려된 탄소성 재료, 강체 재료, 포옴 재료 및 이방성 재료등으로 정면충돌 해석 및 측면충돌 해석에 필요하다. 한편 접촉처리 모듈에서 접촉탐색법으로는 주종탐색법과 HITA 알고리즘을 병행하여 사용할 수 있도록 프로그래밍하였으며, 불침투 조건의 처리는 벌칙함 수법을 이용하였다.

• Journal of the Korean Institute of Gas
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• v.6 no.4 s.18
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• pp.47-52
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• 2002

Analytical studies have been performed to investigate the strength of the membrane and the reaction force at the anchor point. Using nonlinear FEM code and experiments, the stress analysis of the corrugated membrane related the cryogenic liquid pressure and thermal loading is performed to ensure the stability and fatigue strength of the membrane. This paper reports on the FEM results of membrane.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.57-64
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• 2001

For the dynamic nonlinear analysis of stiffened plate and shell structures, total Lagrangian formulation is presented based upon the degenerated shell element considering finite rotation effects. Assumed strain concept is adopted in order to overcome shear locking phenomena and to eliminate spurious zero energy mode. In the elasto-plastic analysis, the return mapping algorithm based on the consistent elasto-plastic tangent modulus is applied to collapse analysis of shell structures. Newmark integration method is used for dynamic nonlinear analysis of shell structures under dynamic forces.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.220-228
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• 1997

We discuss finite element approximation and use a Mindlin plate element based upon uniformly reduced numerical integration. The finite element selected for use in this work is a four-node, bilinear displacement element based upon the Mindlin theory of plates. Such elements show good accuracy for laminated composite plates when reduced numerical integration is used to evaluate the element marices. This study presents both the experimental and F.E. results for the natural frequencies of CFRPURETHANE-CFRP Composite plate. Good agreement between experimental and calculated frequencies is achived.

• 한국정보교육학회:학술대회논문집
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• 2007.01a
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• pp.209-216
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• 2007

고도의 지식정보사회 속에서 논리적 사고력과 창의력, 문제해결력을 길러주는 프로그래밍 교육의 필요성은 더욱 강조되고 있다. 이에 본 연구에서는 초등학생들에게 적합한 교육용 프로그래밍 언어인 JavaMAL을 활용하여, 프로그래밍의 함수개념 형성을 위한 학습모형을 구안 적용하고 일반화 가능성을 탐색하고자 하였다. 먼저 기초적인 프로그래밍 요소 중 함수개념과 관련된 학습요소를 추출하여 차시별 지도계획을 수립하였다. 또한, 프로그래밍의 함수가 수학적 함수의 모방이라는 것에 착안하여 수학의 '규칙성과 함수'지도 단계를 LOGO의 문제해결력 수업모형인 안내된 발견식 교수법(guided discovery teaching method)에 강화한 후, 인터넷을 활용한 문제해결 수업모형을 구안하였다. 기본명령어와 변수개념을 이미 익힌 계발활동 부서 6학년 아동들을 지도 대상으로 한 달간 웹 기반 JavaMAL 환경에서 학습할 수 있도록 하였으며, 게시판 활동 및 활동지를 통해 함수개념 형성 여부를 측정하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.2
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• pp.1-14
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• 1991

A computer program for the linear elastic buckling anlalysis of thin walled members is developed using a 3-node triangular shell element. The element has real stiffness value for a kinematic degree of freedom associated with rotation about the surface normal at each node. The validity of the present computer program is demonstrated through the plate buckling analysis and the lateral-torsional buckling analysis of a straight beam. Then, simply supported circular arches subjected to uniform bending are analyzed and the results are compared with existing solutions.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.2
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• pp.141-154
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• 1993

In this paper, a method to calculate the ultimate compressive strength of welded one-sided stiffened plates simply supported along all edges is proposed. At first initial imperfections such as distortions and residual stresses due to welding are predicted by using simplified methods. Then, the collapse modes of the stiffened plate are assumed and collapse loads for each mode are calculated. Among these loads, the lowest value is selected as the ultimate strength of the plate. Collapse modes are assumed as follows ; (1) Overall buckling of the stiffened plate$\rightarrow$Overall collapse due to stiffener bending (2) Local buckling of the plate part$\rightarrow$Local collapse of the plate part$\rightarrow$Overall collapse due to stiffener yielding (3) Local buckling of the plate part$\rightarrow$Overall collapse due to stiffener berthing (4) Local buckling of the plate part$\rightarrow$Local collapse of the plate part$\rightarrow$Overall collapse due to stiffener tripping. The elastic large deflection analysis based on the Rayleigh-Ritz method is carried out, and plastic analysis assuming hinge lines is also carried out. Collapse load is defined as the cross point of the two analysis curves. This method enables the utimate strength to be calculated with small computing time and a good accuracy. Using the present method, characteristics of the stiffener including torsional rigidity, bending and tripping can also be clarified.

• Journal of the Society of Naval Architects of Korea
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• v.39 no.2
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• pp.61-68
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• 2002

From the viewpoint of linear fracture mechanics, the crack propagation behavior of two different structures having the same K-a relationship could be considered identical. In this study the stress distribution in an infinitely wide cracked plate with the same K-a relationship as in a real structure is defined as the equivalent stress distribution. Fatigue life of a real structural element can be predicted by applying the equivalent stress distribution to a simple structural element, and performing a fatigue crack propagation analysis. The K-a relationship for a structural member can be estimated by a finite element method or a simplified prediction method. The validity to obtain effective crack driving stresses by using the equivalent stress-distribution is examined.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.8
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• pp.25-32
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• 2021

Washboarding is a crucial problem occurring on unpaved roads. This phenomenon involves the formation of ripples on the surface of the unpaved road and causes a critical problem to vehicles and riders. The phenomenon is affected by several parameters, but we focused on the velocity and the size of the rotating body. In the precedent research, we observed that a critical velocity existed for the occurrence of the phenomenon, and the phenomenon's grade was related to the velocity. Therefore, this study, using a discrete element method, aimed to analyze the relation between the velocity and the size of the rotating body for the occurrence of the phenomenon and perform a fast Fourier transform (FFT) analysis to determine the correlation between the phenomenon and the period. The study observed that the critical velocity could vary from the velocity and the size of the rotating body, and there was a certain range of frequency for the occurrence of the Washboarding phenomenon.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.91-103
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• 2014

High performance steel for bridges(HSB 800) with a minimum tensile stress of 800MPa was recently developed. However, the study for local buckling behavior of plate girders considering interactive effects of flanges and webs is still insufficient. In this study, the flange local buckling(FLB) strength of plate girders with HSB 800 was evaluated by nonlinear finite element analysis. The flanges and webs of plate girders having I-section were modeled as 3D shell elements in the nonlinear analysis. Initial imperfection and residual stress were imposed on the plate girder. The high performance steel was modeled as a multi-linear material. Thus, parametric study of compression flanges with a compact, noncompact and slender web was performed. The flange local buckling behavior of plate girders was analyzed, and the nonlinear analysis results were compared with the nominal flexural strength of both AASHTO LRFD(2012) and KHBDC LSD(2012) codes.