• 한국정밀공학회지
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• 제17권3호
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• pp.192-199
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• 2000

The spot-welded automotive side member which has a hat-shaped section and a double hat shaped section has been tested on the axial static(10mm/min) and quasi-static(50mm/min) compressing load. The collapse characteristics of automotive sections have been reviews on shift on shape and in width of the spot-voiding on the flange. On the basis of the results of tests and reviews, the optimum energy absorption capacity of the structure has been studied.

• 한국정밀공학회지
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• 제17권5호
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• pp.195-201
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• 2000

The fundamental spot welded sections of automobiles (hat-shaped and double hat-shaped sections) absorb most of the energy in a front impact collision. The sections of various thickness, shape and weld width on the flange lave been tested on axial impact crush load (Mass 40kg, Velocity 7.19m/sec) using a vertical air pressure crash est device Characteristics of impact collapse have been reviewed and a structure of optimal energy absorbing capacity is suggested.

• 한국정밀공학회지
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• 제17권12호
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• pp.129-136
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• 2000

In the frontal collision the spot welded hat-shaped section side member is the fundamental structure for automobiles and has a great amount of absorbing capacity. For this reason LS-DYNA3D has been used for analyzing impact collapse characteristics on hat shaped section member with respect to the valuables; thickness, width ratio and spot weld potch on impact load(7.19m/sec, 1034J). By comparing the results from simulation and the experimental results, the utilization of simulation has been certified.

• 대한기계학회논문집A
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• 제25권1호
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• pp.98-105
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• 2001

The fundamental and widely used spot welded sections of automobiles (hat and double hat-shaped section members) absorb most of the energy in a front-end collision. The sections were tested on axial static(10mm/min) and quasi-static(1000mm/min) loads. Based on these test results, specimens with various thickness, shape and spot weld pitch on the flange have been tested with impact velocity(7.19m/sec) the same as a real life car clash. Characteristics of collapse have been reviewed and a structure of optimal energy absorbing capacity is suggested.

• 한국자동차공학회논문집
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• 제10권2호
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• pp.212-219
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• 2002

In the frontal collision of cars, front parts of cars such as engine rail and side members that are composed of hatted section tubes should absorb most of the collision energy far the passenger compartment not to be deformed. For these reasons the study on the collapse characteristics, maximum crushing load and energy absorption capacity of hatted section tubes are needed. In this study, top hatted section tubes and double hatted section tubes are investigated. The maximum crushing load of hatted section tubes is induced from plastic buckling stress of plates by considering that the hatted section tubes are composed of plates with each different boundary conditions and that its material has a strain hardening effect. On this concept maximum crushing load equations of hatted section tubes are derived and verified by experiments. from the results of experiment, the differences of collapse characteristics between top hatted section tube and double hatted section tube are analysed. And mean crushing loads of hatted section tubes from experiments are compared with other theory.

• 대한기계학회논문집
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• 제19권5호
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• pp.1251-1258
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• 1995

An elastic buckling analysis of single hat rectangular tubes is carried out. Based on Bleich's buckling theory for elastically restrained plates, a method to estimate the compliance of the supporting plates for the buckling plate and to compensate the effects of compression force acting on the supporting plates is offered. Necessary assumptions which enable an analytic approach to be used are also given. The present results are compared with the finite element results obtained from ABAQUS.

• 한국생산제조학회지
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• 제21권6호
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• pp.865-870
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• 2012

CFRP of the advanced composite materials as structure materials for vehicles has a widely application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness compared with conventional materials. This study is to investigate the energy absorption characteristics and collapse mode of CFRP single and double hat shaped structural member under the axial static collapse test. The CFRP single and double hat shaped structural members stacked at different angles (${\pm}15^{\circ}$, ${\pm}45^{\circ}$, ${\pm}90^{\circ}$, $90^{\circ}/0^{\circ}$ and $0^{\circ}/90^{\circ}$ where the direction on $0^{\circ}$ coincides with the axis of the member). The axial static collapse tests were carried out for each member. Collapse mode and energy absorption characteristics of the each member were analyzed.

• 한국공작기계학회논문집
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• 제15권6호
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• pp.114-120
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• 2006

Front-end side members of vehicles are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was undertaken to analyze the energy absorption characteristics of spot welded hat and double hat-shaped section members under the axial collapse. The experiments were performed with respect to the various collapse velocities. It was expected that para-closed sections would show collapse characteristics which be quite different from those of perfectly closed sections. The collapse velocities were selected as follows: the velocities in the hat-shaped section members were 0.00017m/sec, 0.017m/sec, 4.7m/sec, 6.5m/sec, 6.8m/sec, 7.2m/sec, and 7.3m/sec those in the double hat-shaped section members were 0.00017m/sec, 0.017m/sec, 6.5m/sec, 6.8m/sec, 7.2m/sec 7.3m/sec, and 7.9m/sec. In the program system presented in this study, an explicit finite element code, LS-DYNA3D, is adopted for simulating complicated collapse behavior of the hat and double hat-shaped section members under the same condition of the collapse test. The validity of simulation was confirmed by the comparison between the simulation result and the collapse experiment.

• 한국안전학회지
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• 제27권6호
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• pp.20-25
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• 2012

Currently, the most important purpose in designing automobile is environment-friendly and safety performance aspect. CFRP(Carbon Fiber Reinforced Plastics) of the advanced composite materials as structure materials for vehicles, has a wide application in lightweight structural materials of air planes, ships and automobiles because of high strength and stiffness. In this study, experimental investigations are carried out for CFRP single and double hat shaped section member in order to study the effect of various stacking condition. They were cured by heating to the appropriate curing temperature($130^{\circ}C$) by means of a heater at the vacuum bag of the autoclave. The stacking conditions were selected to investigate the effect of the interface numbers. The CFRP single and double hat shaped section members which manufactured from unidirectional prepreg sheets were made of 8ply. The static collapse tests performed and the collapse mode and energy absorption capability were analyzed according to interface number.

• Clinical and Experimental Pediatrics
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• 제45권7호
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• pp.891-895
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• 2002

목 적 : 터너 증후군에서 신기형은 보고자에 따라 차이가 있으나 대개 33-60%의 발생빈도를 나타낸다. 국내에서는 노 등이 9.2%의 동반율을 보고하면서, 한국 소아 터너 증후군 환자에서 신기형의 동반율이 다른 외국에 비해 낮을 가능성을 제시하였다. 이에 저자 들은 본 연구를 통하여 터너 증후군 환자에서 신기형의 발생빈도를 조사하고, 핵형에 따라 신기형의 발생 빈도에 차이가 있는지를 분석하였다. 방 법: 1995년 1월부터 인제의대 부산백병원과 영남대학교병원에서 염색체 검사를 시행하여 터너 증후군으로 진단된 33명의 환자를 대상으로 하였다. 환자 전원을 대상으로 경정맥 신우 조영술을 실시하였으며, 일부 환자에서는 복부 초음파 검사 및 99mTc-DMSA 신주사(renal scan)를 함께 시행하였다. 환자들은 핵형에 따라 전형적인 45, X형, 모자이시즘(mosaicism)인 경우 그리고 X 염색체의 구조상의 이상(structural aberration)이 있는 경우로 분류하였다. 결 과 : 염색체 핵형의 비율은 전형적인 45, X형이 18명으로 54.5%를 차지하였고, 모자이시즘이 11명으로 33.3% 그리고 X 염색체의 구조상의 이상이 있는 경우가 4명으로 12.2%를 차지하였다. 33명의 터너 증후군 환자 중 12명에서 신기형이 동반되어 전체적으로 36.4%의 빈도를 나타내었다. 동반된 신기형의 종류를 살펴보면 마제신이 4명에서 관찰되었으며, 단일신이 1명, 회전이상이 1명, renal collecting system의 이상이 6명에서 관찰되었다. 핵형에 따른 신기형의 빈도를 살펴보면 전형적인 45, X형의 경우 44.4%로 모자이시즘과 X 염색체 구조적 이상의 26.7%보다 발생 빈도가 높았으나 통계적으로 유의하지는 않았다(P>0.05). 결 론: 본 연구에서 터너 증후군 환자에서의 신장 기형의 동반율은 36.4%였다. 이는 외국의 다른 연구 결과와 비슷한 발생빈도를 보여 준다. 핵형에 따른 신 기형의 빈도는 전형적인 45, X형의 경우 44.4%였으며, 모자이시즘과 X 염색체 구조상의 이상인 경우 26.7%로 나타났다. 그러므로 터너 증후군 환자에서 신장 초음파 검사나 경정맥 신우 조영술 검사를 시행하여 신장 기형의 동반 여부를 조사하는 것이 환자의 질적인 관리에 매우 중요하다고 생각한다.