• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.6 no.2
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• pp.10-18
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• 1988

In the three-dimensional analysis and deformation analysis of large structures, efficient is the use of the multiple method of close range photogrammetry which approaches the object distance. This study analyzes the influence of errors according to the overlap, the control points, and the object distance, to solve the problems which are raised in the multiple method. A wall-board, 7 meters by 3 meters, was used as a test field on which a total of 225 unknown points were equally disposed. The photographs with changing the overlap and object distance were taken by P-31 camera system. a total of 143 negatives are used in this study for computing 3-dimensional coordinates and its standard errors, and bundle adjustment of strips and blocks developed with on-line system is applied. In case of decreasing the number of control points, simulation error increases but actual error decreases and increases again. Due to the changed of object distances Z error represents largely compared to X, Y error, but good results in Z can be obtained by increasing the redundancy. And simulation error or actual error shows best results at the endlap of about 70%. To sum up this study, approprate arrangement of control points and overlap is meaningful, and multiple method by short object distance will be widely used to precision and deformation analysis of critical structures.

• Proceedings of the Korean Geotechical Society Conference
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• 1993.10a
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• pp.43-50
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• 1993

It has been past for many years that soil-cement used in the field of roadway pavement in America and Europe. Though the design and construction criteria on soil-cement pavement have been well setablished in Korea's specificaions, this method has not been applied in roadway pavements, in practices. It is mainly caused by the lacks of experiences in soil-cement pavement design and construction. In this study, the problems of soil-cement pavement in use were explored, and the structure and fatigue like of soil-cement bases and subbases were estimated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.11
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• pp.979-986
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• 2016

The tripod shafts of constant-velocity joint are used in both the trains KTX and KTX-sanchon. It is an important component that connects the motor reduction unit and the axle reduction unit in a power bogie. The tripod shaft not only transmits drive and brake torque in the rotational direction, but also slides in the axial direction. If the drive system is loaded with an excessive torque, the fuse part of the shaft will be fractured firstly to protect the other important components. In this study, a rig was developed for conducting torsion tests on the tripod shaft, which is a type of mechanical fuse. The tripod shafts were subjected to torsional fracture test and torsional fatigue test on the rig. The weak zone of the tripod shaft was identified, and its fatigue life was predicted using finite element analysis (FEA). After analyzing the FEA results, design solutions were proposed to improve the strength and fatigue life of the tripod shaft. Furthermore, the deterioration trend and time for failure of the tripod shaft were verified using the hysteresis loops which had been changed with the advancement of the torsional fatigue test.

• Journal of the Korean Society for Railway
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• v.2 no.2
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• pp.31-38
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• 1999

Two representative types of the AGT (Automated Guideway Transit) system, which are bogie and steering types, are available for the side-guided system. Each system primarily consists of the bogie frame, suspensions, wheelsets and axles, braking system and transmission system. Among these components, the bogie frame is one of the most significant components subjected to the whole vehicle and passenger loads. This paper describes structural analyses and associated fatigue analyses for each bogie frame depending on the various loading conditions on a basis of the railway vehicle code UIC 515-4. Subsequently, comparisons are made between those two types to estimate which type is more reliable in terms of strength and fatigue. It is observed that the bogie type is a little advantageous over the steering one from the strength analysis. However, the two types are found to be in a reliable range of fatigue even though a realistic fatigue load case is further carried out. In addition, an optimal size of thickness is suggested for designs of the bogie frame.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.44-50
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• 2015

This study investigated the durability of the under bar of a car through structural and fatigue analysis. Model 1 had the lowest value among three kinds of models. In the case of the maximum equivalent stress and displacement at structural analysis, model 1 showed the highest durability. Also, models 3 and 2 showed structural durability in order of this value. In the case of fatigue analysis, the maximum fatigue lives of the three models were equal to $2{\times}10^7$cycles. However, model 1 showed the highest value among the three models, as the minimum fatigue life of model 1 becames 92.56 cycles. Also models 3 and 2 showed fatigue durability in order of this value. The maximum possibility of fatigue damage for models1,2,and 3 became 30%. If the results of this study are applied to change the design shape of the under bar of cars, the ride comfort for automobile passengers and car durability can be improved.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.69-72
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• 2014

If LNG is leaked from 9% Ni steel inner tank by damage, LNG is retained by outer concrete tank. Then large tensile stress can be caused at cylindrical bottom of outer tank by temperature difference between outer and inner surface of outer tank. Therefore, in order to reduce the tensile stress is caused by temperature difference, corner-protection is installed with insulation and 9% Ni steel as a second barrier. In this paper, using finite element method, structural analysis was performed for rectangular and circular shape of knuckle and based on the results, fatigue life of welds of corner protection was predicted. As a consequence of structural analysis, safety factor of circular knuckle shows 33% bigger than rectangular one shows, and circular knuckle has 25% bigger fatigue life time than rectangle has. These results can be applied to life time assessment and design optimization in the future.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.201-208
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• 2009

Recently, the wind energy has been widely used as a renewable energy resource due to lack and environmental issues of the mostly used fossil fuel. This work is to develop a 500W class small wind turbine blade which will be applicable to relatively low speed region like Korea and for the domestic use. For this blade a high efficiency wind turbine blade was designed with the proposing aerodynamic design procedure, and a light and low cost composite structure blade was designed considering fatigue life. Structural analyses including load case study, stress, deformation, buckling and vibration analysis were performed using the Finite Element Method. The fatigue life was estimated using the load spectrum analysis and the Miner rule. In order to evaluate the designed blade, the structural and aerodynamic performance tests were carried out, and the test results were compared with the analysis results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.558-567
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• 2020

This study examined the defect characteristics of fuel flow proportioner-mounted structures to analyze the causes of structural defects during aircraft operation. System vibrations and single component vibrations that occur during aircraft operations are usually the cause of structural defects. The fuel flow proportioner causes a defect in the support structure due to the vibration caused by the pressure change caused by the sudden increase in the flow rate. Defects in the support structure of the fuel flow proportioner are not correlated directly with the cracking of the maneuver, and flight time according to aircraft operation analysis is related to the use of A/B. The structural reinforcement configuration was confirmed through static and life analysis of the cracks of the bracket mounted under the fuel flow proportioner for improvement of the defect. An analysis of the reinforcement revealed a minimum structural strength of +0.15. Structural life analysis confirmed that the stress acted on the site under 15Ksi. The fatigue life was confirmed to be more than 7,700 Cycles.

• Journal of the Korea Convergence Society
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• v.11 no.4
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• pp.189-193
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• 2020

In this study, the structural analysis of the track was performed according to the gap between the rails due to thermal expansion by the frictional contact between the wheels of the train in motion. The equivalent stress and total deformation at the condition for which the gap between joints are wide as the winter condition (model B) can be seen to happen more than at the summer condition (model A) in which the joints are narrow. If the results of this study are applied to the design of railway tracks, it is thought to be highly useful in preventing fatigue failure and increasing its durability. By applying the durability analysis at the seam of railroad track by season, this investigation result is seen to be favorable as the convergent research applied to the aesthetic design.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.1
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• pp.59-65
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• 2004

Recently, as steel structures become higher and more long-spanned, application of high strength steel. SM570, is considered, For accurate seismic design, seismic analysis of steel structures needs a constitutive equation describing the characteristic of steel materials under non-proportional cyclic loading, While the use of SM570 material is much increased these days, research for description and generalization of cyclic plasticity behavior are insufficient, In this study, a cyclic plasticity model is proposed by results of material tests, i.e, monotonic and low cycle tests, Proposed cyclic plasticity model is applied to 3-Dimensional FE program and we carried out seismic analysis of pipe-section steel pier using SM570, Comparison between experiment and analysis results shows that the proposed constitutive equation is able to describe exactly the complicated plastic behavior of steel structure using SM570.