• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2004.04a
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• pp.340-345
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• 2004

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.2
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• pp.75-80
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• 2004

Vehicle structures are composed of many substructure connected to one another by various types of mechanical joints. In vehicle engineering it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. It is difficult to obtain the accurate load history of specified positions because of the errors such as modeling, measurement and etc. In the beginning of design exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the procedure of practical dynamic force determination is developed by the combination of the principal stresses of F. E. Analysis and experiment. Least square pseudo inverse matrix is adopted to obtain in inverse matrix of analyzed stresses matrix. The error minimization method utilizes the inaccurate measured error and the shifting error that the whole data is stiffed over real data. The least square criterion is adopted to avoid these non. Finally, to verify the proposed procedure, a bus is analyzed. This measurement and prediction technology can be extended to the structural modification of any geometric shape in complex structure.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.928-933
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• 2004

Despite the number of steel bridges being under in service more than 50 years reaches about 50$\%$ in present, the quantitative estimation in maintenance on steel railway bridges is not possible because a ton of the field data in the bridges have not been plentifully accumulated. Therefore, a series of field tests on the steel plate girder bridge, the typical types of steel railway bridges, are executed, and the stress characteristics of main members in steel plate girder railway bridges are quantitatively estimated in this study.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.106-113
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• 2004

Most of mechanical structures are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. In this study, the dynamic response of vehicle structure to external forces is classified an inverse problem involving strains from the experiment and the analysis. The practical dynamic forces are determined by the combination of the analytical and experimental method with analyzed strain by quasi-static finite element analysis under unit force and with measured strain by a strain gage under driving load, respectively. In a stressed body, inter-molecular chemical bonds are failed beyond the certain magnitude. The failure of molecular structure in material is considered as a time process of which rate is determined by mechanical stress. That is, the failure of inter-molecular chemical bonds is the fatigue lift of material. This kinetic concept is expressed as lethargy coefficient. And S-N curve is obtained with the lethargy coefficient from quasi-static tensile test. Equivalent practical dynamic force is obtained from the identification of practical dynamic force for one loading point. Using the practical dynamic force and S-N curve, fatigue life of a window pillar is analyzed with FEM under the identified force by the procedure of above mentioned.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.113-116
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• 2008

본 연구에서는 차량-교량간 상호작용효과가 교량의 동적거동에 미치는 영향을 분석하기 위한 차량 주행 하중에 대한 실험적 및 이론적 연구를 수행하였다. 이를 위하여 차량 교량간 상호작용이 포함된 이동질량형 윤하중 실험기를 단순교형식 교량에 적용하여 반복주행실험을 수행하였다. 이동질량 반복 주행실험 결과를 분석하여 차량-교량간의 상호작용을 포함한 가속도 형태의 실동주행차량가속도를 규명하였다. 규명된 차량의 실동주행차량가속도를 범용 해석프로그램에 적용하여 차량-교량 상호작용을 재현할 수 있었다. 또한 차량주행시 교량의 사용성평가에 대한 기본자료를 판단할 수 있었다.

• Journal of the Society of Disaster Information
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• v.7 no.3
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• pp.190-197
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• 2011

In this paper, an analytical and experimental study is performed in order to determine the effects of interaction between a vehicle and a structure. For this purpose, a wheel tracking machine and an adequate single span bridge are designed. Results presented in the paper show that the real vehicle tracking accelerations including the interaction between the vehicle and the structure produce additional effects on the dynamic behavior of the structure including reversal and contrary behavior. Also, the interaction between the vehicle and the bridge is reproduced by applying the identified real vehicle tracking accelerations to a general finite element analysis program.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.33-38
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• 2008

Most structures of vehicle are composed of many substructures connected to one another by various types of mechanical joints. In vehicle engineering, it is important to study these jointed structures under random frequency vibration for the evaluations of fatigue life and stress concentration exactly. It is rarely obtained the accurate load history of specified positions in a jointed structure because of the errors such as modeling, measurement, and etc. In the beginning of design, exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the hybrid method of practical dynamic load determination is developed by the combination of the principal stresses from F. E. Analysis and test of a jointed structure. Least square pseudo inverse matrix is adopted to obtain an inverse matrix of analyzed stresses matrix. The error minimization method utilizes the inaccurate measured error and the shifting error that the whole data is stiffed over real data. The least square criterion is adopted to avoid these errors. Finally, to verify the proposed system, a heavy-duty bus is analyzed. This measurement and prediction technology can be extended to the different jointed structures.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.5
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• pp.118-123
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• 2001

Most structures of automobile are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic farces for the evaluations of fatigue life and stress concentration exactly. It is rarely obtained the accurate load history of specified positions because of the errors such as modeling, measurement, and etc. In the beginning of design, exact load data are actually necessary for the fatigue strength and life analysis to minimize the cost and time of designing. In this paper, the procedure of practical dynamic load determination is developed by the combination of the principal stresses of F.E. analysis and experiment. Inverse problem and least square pseudo inverse matrix are adopted to obtain an inverse matrix of analyzed stresses matrix. Pseudo-Practical dynamic load was calculated for Lab. Test of sub-structure. GUI program(PLODAS) was developed for whole of above procedure. This proposed method could be extended to any geometric shape of structure.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.16-24
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• 2009

In this study, fatigue crack growth rate of a cracked railway bogie frame under variable amplitude loading is predicted by applying linear elastic fracture mechanics. For this purpose, we find the critical points by reference surveying on cracked railway bogie frames. And we make an effective load history by synthesizing the dynamic load measured from the critical points of railway bogie frame during commercial line operation and the static load calculated from structural analysis. Crack growth analyses are performed at the 3 critical points under the commercial operation loading condition by assuming an initial crack size as 40 mm. and the results are compared with the experimental results from Japanese railway bogie frame crack growth case. From the analysis results, we find that around 500,000 km operating distance is necessary to bring crack growth from the initial crack to unstable crack. And it takes around 3.8 normal operating years. We conclude that it is enough time to detect the crack between normal maintenance period.

• Journal of the Korean Society for Precision Engineering
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• v.2 no.1
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• pp.21-27
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• 1985

차량, 항공, 교량 및 기계구조물 등 랜덤한 실동하중을 받는 구조물의 응력 및 변위, 진동등의 피로 Data 또는 TRAFFIC 등에 의한 건축물의 변위 및 응력발생빈도를 집록하기 위한 Histogram Recorder System에 대한 내용과 측정예를 소개하고자 한다. 본 System은 8(4)챈 널의 스트레인 게이지 또는 스트레인 게이지식 각종변환기와 각종 Sensor로부터의 출력전압 등 Analog 입력을 수록하여, Digital 처리하여 micro computer를 사용, 미리 프로그램된 방식에 따라 측정과 동시에 실동시간으로 해석처리하여 빈도수로서 내부에 기억저장 시키는 것이다. 따라서 본 Histogtram Recorder 본체는 소형으로 견고하며 조금도 제어부분을 갖지 않고 소요의 해석방법의 프로그램백만을 셋트한 개별의 제어기만을 통해가지고 프로그램을 기입만 하며는 그다음은 손하나 안대고도, 그리고도 또 측정중에 제3자에 의한 제어조작 잘못이 발생할 위험도 없고 1 년이상에 걸친 장기간의 .+-. 32 Slices의 각 레벨당 각각 40 억을 넘는 대량의 빈도수를 자동적으로 집록 할 수가 있다. 집록된 Data는 제어장치에 의해 정리된 Datam는 제어장치에 의해 정리된 Histogram의 형태로 읽어나갈 수가 있어 관찰이 가능할 뿐만 아니라 프린터기록 또는 기록장치에 이송시켜서 Data 만 따로 가져올 수가 있어 필요에 따라서는 one line으로 Host computer에 접속시킬 수가 있어 더욱 고도의 처리를 할 수가 있다. 빈도해석프로그램으로서는 극대, 극소, 최대, 최소, 진폭, 시간 등을 pack으로서 준비되어 있어 이에 대한 시스템의 고성 동작 및 성능등을 소개하고자 한다.