• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.10
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• pp.1509-1516
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• 2004

During fuel irradiation tests, all parts of cylindrical structure with multiple holes act as heat sources due to fussion heat and ${\gamma}$-flux. The high temperature is especially generated in the center of pellet. Because of the high temperature, many problems occur, such as melting of pellet and declining of heat transfer between cladding and coolant. In this paper, it is attempted to minimize the temperature of pellet using optimization method. For thermal and optimization analysis of structure, the finite element method code, ANSYS 5.7 is used. Through the optimum design process, the temperature of SBT diminished 10％ and the temperature of OBT diminished 18％.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1402-1405
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• 2005

This paper describes the result of structure analysis of secondary bogie frame. The purpose of the analysis is to evaluate an safety which secondary bogie frame shall be considered fully sufficient rigidity so as to satisfy proper system function under maximum load. Secondary bogie system consist of bogie frame, suspensions, wheel-sets, and brake system. Among these component, the bogie frame is most significant component subjected to the vehicle and passenger loads. The evaluation method is used the JIS E 4207 specification throughout the FEM analysis. The analysis results have been very safety and stable for design load conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.404-409
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• 2005

This paper describes the result of structure analysis and load test for bogie frame. The purpose of the analysis and test is to evaluate an safety which body structure shall be considered fully sufficient rigidity so as to satisfy proper system function under maximum load. Bogie system consists of bogie frame, suspensions, wheel-sets, braking system and transmission system. Among these component, the bogie frame is most significant component subjected to the vehicle and passenger loads. The evaluation method is used the JIS E 4207 specification throughout the FEM analysis and static load test. The analysis and test results have been very safety and stable for design load conditions.

• Journal of KSNVE
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• v.8 no.2
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• pp.336-345
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• 1998

The dynamic instability of cylindrical shell with clamped-free boundary condition subjected to constant follower force or $P_0 + P_1cos {\Omega}_t$ type pulsating follower force is analyzed. The motion of shell is modeled using the shell theory considering rotary inertia and shear deformation, and analyzed with finite element method. In case of constant follower force, the changes of eigenvalues dependent on the magnitude of applied load are investigated and the critical loads are obtained. In case pulsating follower force, instability regions of exicitation frequency are obtained by modal transform with right and left modal matrix and by multiple scales method. The effects of thickness ratio and aspect ratio on the instability of shell are studied.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.1
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• pp.13-20
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• 2009

The IPSAP which is a finite element analysis program has been developed for high parallel performance computing. This program consists of various analysis modules - stress, vibration and thermal analysis module, etc. The M orthogonal block Lanczos algorithm with shiftinvert transformation is used for solving eigenvalue problems in the vibration module. And the multifrontal algorithm which is one of the most efficient direct linear equation solvers is applied to factorization and triangular system solving phases in this block Lanczos iteration routine. In this study, the performance enhancement procedures of the IPSAP are composed of the following stages: 1) communication volume minimization of the factorization phase by modifying parallel matrix subroutines. 2) idling time minimization in triangular system solving phase by partial inverse of the frontal matrix and the LCM (least common multiple) concept.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.959-962
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• 2002

This paper presents a method of constructing the universal multiple processing element unit(UMPEU) based on De Bruijn Graph. The proposed method is as following. Firstly we propose transformation operators in order to construct the De Bruijn graph using properties of graph. Secondly we construct the transformation table of De Bruijn graph using above transformation operators. Finally we construct the De Bruijn graph using transformation table. The proposed UMPEU is capable of constructing the De Bruijn geraph for any prime number and integer value of finite fields. Also the UMPEU is applied to fault-tolerant computing system, pipeline class, parallel processing network, switching function and its circuits.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.9-14
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• 2001

A new model utilizing a transfer function is introduced in the present paper for analizing motion errors of hydrostatic tables. Relationship between film reaction force in a single hydrostatic pad and form error of a guide rail is derived at various spacial frequencies by finite element analysis, and it is expressed as a transfer function. This transfer function clarifies so called averaging effect of the oil film quantitively. For example, it is found that the amplitide of the film reaction force is reduced as the spacial frequency increases or relative width of the pocket is reduced. Motion errors of a multiple pad table is estimated from transfer function, geometric relationship between each pads and form errors of a guide rail, which is named as Transfer Function Method. Calculated motion errors by TFM show good agreement with motion errors calculated by Multi Pad Method, which is considered entire table as an analysis object. From the results, it is confirmed that the proposed TFM is very effective to analyze the motion errors of hydrostatic tables.

• Structural Engineering and Mechanics
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• v.42 no.3
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• pp.425-448
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• 2012

In this paper, a new damage detection and quantification method has been presented to perform detection and quantification of structural damage under ambient vibration loadings. To extract modal properties of the structural system under ambient excitation, natural excitation technique (NExT) and eigensystem realization algorithm (ERA) are employed. Sensitivity matrices of the dynamic residual force vector have been derived and used in the parameter subset selection method to identify multiple damaged locations. In the sequel, the steady state genetic algorithm (SSGA) is used to determine quantified levels of the identified damage by minimizing errors in the modal flexibility matrix. In this study, performance of the proposed damage detection and quantification methodology is evaluated using a finite element model of a truss structure with considerations of possible experimental errors and noises. A series of numerical examples with five different damage scenarios including a challengingly small damage level demonstrates that the proposed methodology can efficaciously detect and quantify damage under noisy ambient vibrations.

• Structural Engineering and Mechanics
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• v.34 no.1
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• pp.97-107
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• 2010

Nonlinear thermoelastic static response characteristics of laminated composite conical panels are studied employing finite element approach based on first-order shear deformation theory and field consistency principle. The nonlinear governing equations, considering moderately large deformation, are solved using Newton-Raphson iterative technique coupled with the adaptive displacement control method to efficiently trace the equilibrium path. The validation of the formulation for mechanical and thermal loading cases is carried out. The present results are found to be in good agreement with those available in the literature. The adaptive displacement control method is found to be capable of handling problems with multiple snapping responses. Detailed parametric study is carried out to highlight the influence of semicone angle, boundary conditions, radius-to-thickness ratio and lamination scheme on the nonlinear thremoelastic response of laminated cylindrical and conical panels.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.2
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• pp.77-86
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• 1999

In the previous $paper^{(1),(2)}$, a geometrically non-linear finite element formulation of spatial cables subjected to self-weights and support motions was presented using multiple noded cable elements and how to determine the initial equililbrium state of cables was addressed. In this paper, in order to perform dynamic non-linear analysis of ocean cables subjected to support motions and earthquakes, a numerical method to calculate Morison forces and incorporate effects of earthquake motions is presented based on the Newmark method. Challenging example problems are presented in order to investigate dynamic non-linear behaviors of ocean cables subjected to support motions and earthquake loadings.