• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.1-9
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• 2010

The purpose of this study is to analyze the bumper mounting structure of passenger vehicles at low speed collision. In order to improve the repairability and damageability of the vehicle, the low speed crash tests of RCAR(Research Council for Automobile Repairs) standard(front & rear 15km/h 40% offset crash test) were carried out for analysis of 3 different types of bumper mounting structures. The results of experiments show that the impact energy absorbing ability of bumper stay with rectangular crash box type vehicle which is inserted into the bumper rail was superior to another two different bumper mounting structures that are applied to many passenger vehicles. In this thesis, well designed bumper mounting structure such as rectangular crash box type can enhance the safety of occupants as well as contribute to reduce repair cost at low collision accident by improving repairability and damageability of vehicle.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.5
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• pp.23-32
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• 2012

Research on steel plate concrete (SC) structures for the modularization of nuclear power plants have been performed recently in Korea. In this study, the seismic capacity and stiffness characteristics of unstiffened SC shear walls under the effects of earthquakes were investigated through static pushover tests. Failure modes, sectional strength, and stiffness characteristics of SC structures under lateral loads were inspected by analyzing the experimental results. The strengths obtained by the experiments were also compared with those derived by the design code of the SC structures. One of the main failures of unstiffened SC shear walls was found to be the type of bending shear failure due to the debonding of the steel plate at the concrete interface. The ductility capacity of SC structures was also confirmed to be improved, which is considered to be a confining effect on steel plates in the longitudinal behavior of SC structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.615-624
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• 2014

It has been well known the sloshing pressure has complex shape and various patterns. The pattern of sloshing pressure is variously characterized by the pressure amplitude, duration time and skewness. The structural response induced by the sloshing pressure is also affected by the pattern of sloshing pressure and the type of structural members. In order to understand the structural response by the perspective view of categorized pattern, it is more efficient to make simple sloshing pressure pattern than to reflect the complex pressure history. In this study, the sloshing pressures obtained by the small scale model test are simplified with respect to their duration and skewness. Dynamic analyses of Mark-III LNG CCS are then parametrically performed with the consideration of various types of sloshing impact. Meanwhile, the failure pressures given the duration and skewness are investigated after parametric calculations are conducted to investigate the effect of pressure parameters on the structural response.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.2
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• pp.125-132
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• 2019

This paper presents a seismic reliability analysis method for an offshore wind turbine with a twisted tripod support structure under earthquake loading. A three dimensional dynamic finite element model is proposed to consider the nonlinearity of the ground-pile interactions and the geometrical characteristics of the twisted tripod support structure where out-of-plane displacement occurs even under in-plane lateral loadings. For the evaluation of seismic reliability, the failure probability was calculated for the maximum horizontal displacement of the pile head, which is calculated from time history analysis using artificial earthquakes for the design return periods. The application of the subset simulation method using the Markov Chain Monte Carlo(MCMC) sampling is proposed for efficient reliability analysis considering the limit state equation evaluation by the nonlinear time history analysis. The proposed method can be applied to the reliability evaluation and design criteria development of the offshore wind turbine with twisted tripod support structure in which two dimensional models and static analysis can not produce accurate results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.1-9
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• 2017

Spiral reinforcement in a circular column plays an effective role in the ductile behavior of a column through position fixing and buckling restraining of the longitudinal reinforcement, and confining core-concrete. Each country has suggested the minimum volumetric ratio of spiral reinforcement in order to secure the ductility of concrete columns. The minimum volumetric ratio of spiral reinforcement suggested by ACI 318-14 and the national concrete structure design standard was developed based on the theory of Richard et al. (1928); furthermore it has been used until now. However, their theory cannot consider the effects of high strength concrete and high strength reinforcement, and arrangement condition of the spiral reinforcement. In this study, a modified minimum volumetric ratio equation is suggested, which is required to improve the ductility of reinforced concrete circular columns and to recover their stress. The modified minimum volumetric ratio equation suggested here considers the effect of the compressive strength of concrete, the yield strength of spiral reinforcement, the cross sectional area of columns, the pitch of spiral reinforcements and the diameter of spiral reinforcement. In this paper, the validity of the minimum volumetric ratios from ACI 318-14 and this study was investigated and compared based on the results of uniaxial compression experiment for specimens in which the material strength and the spiral reinforcements ratio were used as variables. In the end of the study, the modification method for the suggested equation was examined.

• Journal of Korean Society of Steel Construction
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• v.15 no.1
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• pp.87-96
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• 2003

The Ssteel-Cconcrete (SC) Ccomposite Ccolumn is a new Ccomposite Ccolunin system, where hoops are welded between flanges of H-shapesd steel and concrete is filled in spaces between flanges are filled with con crete. Tests of SC composite columns were performed previously to determine their compression, bending and shear strength, and it showed good structural behavior. But sSince a column is usually subjected to an axial compression force, and bending it ihas needed to be bent forevaluate its structural behavior to be evaluated when its axial load and bending isaresimultaneously applied to the SC composite column. In this paper, tests were conducted to investigate the bending strength of SC composite columns subjected to axial compression force and bending moment. The parameters of the tests were concrete, a stud bolt, a hoop and a magnitude of axial compression. The test results showed that the maximum bending strength and ductility of an SC composite column were increased by 33-42% and 33-63%, respectively, comparinged to those of a bare steel column. Also, the results obtained bywith the Korean Limit State Design Code (LSD) presents a considerably safe side value compared to those of the Eurocode-4 and the Japan Code. However, wWhen the axial compression force is was increased, however, there awere considerable differences between the maximum strength obtained by the test and the LSD analysis. For this reason, it is recommended tothe use of the Eurocode-4 is recommended when calculates the strength of an SC composite column is being calculated, since the Eurocode-4 gives us a better estimation.

• Journal of the Korean Society for Railway
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• v.16 no.5
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• pp.394-401
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• 2013

Here we report the results of an experimental laboratory test to verify the applicability to railway bridges of a PSC I girder of which the upper flange thickness was increased to improve sectional performance. The thicker this flange is, the further upward the neutral axis is moved. If in this way the span length can be increased to 40m long, the bridge may be constructed with four girders instead of five. Therefore, construction cost could be lowered by reducing the weight of the long span structure due to increased sectional efficiency. It was also necessary to be certain that the dynamic performance of this relatively flexible structure would be applicable to railway bridges. Therefore numerical analysis, as well as static and dynamic tests, was carried out for a full-size PSC I girder. Based on these results, it was verified that the performance of the PSC I railway bridge satisfied the performance criteria of the design code.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.1 s.16
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• pp.33-43
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• 2005

The girder wheel load distribution factors stated in the Korean Bridge Specification and AASHTO Standard Specifications do not account for the effect of skewness of plate girders, and very little research has been conducted on girder wheel load distribution factors. The purpose of the study is to propose load distribution factor formulas for skew plate girder bridges which comprise various parameters through structural analysis. To confirm the validity of finite element models used in this study analytic values are compared with the field test results. From the results it should be noted that span length is not such a dominant parameter compared with others. In view of better load distribution of interior girders, skew arranged cross beams or bracing are preferable, furthemore bracing system is more effective than cross beam system. By means of regression analysis on the basis of analytic results wheel load distribution factor formulas are proposed and compared with current codes.

• Journal of Korean Society of Steel Construction
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• v.21 no.1
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• pp.93-103
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• 2009

Two-girder bridge is composed of primary members such as deck slab and main girder, and secondary member such as cross beam, vertical and horizontal stiffeners etc,. Two-girder bridge is prescribed as a non-redundant load path structure in the ASSHTO and the Korean Highway Bridge Design Code. Such structure is that if one girder is damaged, problems of function and safety of the bridge are caused. From the reasons, fatigue cracks in two-girder bridge can affect safety of the bridge seriously. Therefore, in this paper, fatigue evaluation was performed at connection parts of vertical stiffener and web with radius of curvature of scallop of vertical stiffener and thickness of web as variables. Such joint is known as a detail which has high possibility of fatigue crack in the bridge. Based upon the analytical results, preferable joint detail in terms of fatigue and simple empirical formula for fatigue evaluation of the detail were suggested.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.119-126
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• 2008

In 1980 and 1990's most of residential buildings were constructed with relatively low strength concrete of 18 MPa. And, columns were designed considering only vertical loads. In this study, compressive strength tests for low strength RC columns retrofitted by carbon fiber sheets were carried out. Carbon fiber sheet provides constructability and high tensile strength as well as good corrosion resistance characteristics. A pair of carbon sheets were wrapped with ${\pm}60^{\circ}$ angle with respect to longitudinal direction of RC column to increase structural capacity against axial and lateral load simultaneously. Strength and strain patterns and failure modes of specimens were analyzed and prediction equation of increased compressive strength of RC column confined by carbon fiber sheet was proposed based on regression analysis.