• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.2
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• pp.259-267
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• 2004

Most steel frame structures are constructed to one side without considering the arrangement of major-minor axis of column and bracing. This research presents more safety and economic efficiency can be obtained by just rearrangement of major-minor axis. Because most of steel-frame structures are excessively designed with Allowable Stress Design, and it needs to be changed to other specifications. The arrangement of major-minor axis of column is partly referred in AISC-LRFD, but still insufficient. This study compared with the each result from rearrangement of major-minor axis of column, arrangement of bracing, the connecting method of bracing, and consequence with different specifications. Moreover it demonstrated the direction of more economically optimized design.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.4
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• pp.48-55
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• 2001

In this paper, sensitivity analysis for the coupled axial and torsional undamped free vibration of ship propulsion shafting is proposed. The purpose of this study is to effectively and optimally design the resonance frequencies of propulsion shafting affecting barred speed range of main engine by modifying the diameters of intermediate and propeller shafts. The presented method is validated by the sensitivity analysis for the natural frequencies of propulsion shafting of two real large merchant ships. In addition, the changes of natural frequency and resonance main engine speed are discussed in case that the diameter is varied within the range regulated by the rule of shipping register.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.193-196
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• 2008

This paper proposes a method to predict the ductility capacity of reinforced concrete beam-column joints failing in shear after the formations of plastic hinges at both ends of the adjacent beams. The current design code divides joints into two categories: Type 1 for structures in non seismically hazard area and Type 2 in seismically hazard area. While there are many researches related to joint shear strength in Type 1, those in regard to joint ductility capacity of Type 2 are scarce. This paper classified the ductility capacity of beam-column joints into column, joint panel, and beam deformability. Since a brittle failure such as shear or bond failure in the columns must be avoided, column deformability was calculated by elastic analysis. The plastic hinges of the adjacent beams affect joint deformability. Therefore, the prediction of joint deformability was calculated with consideration to the degradation of the diagonally compressed concrete due to the strain penetration.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.4
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• pp.344-350
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• 2013

The purpose of this study is to examine the structural stability of a low speed 200 W class gyromill type vertical axis wind turbine system. For the analysis, a commercial code is adopted. The pressure distribution on the rotor blade surface is examined in detail. In order to perform unidirectional FSI(Fluid-Structure Interaction) analysis, the pressure resulted from CFD analysis has been mapped on the surface of wind turbine as load condition. The rotational speed and gravitational force of wind turbine are also considered. The results of FSI analysis show that the wind turbine reveals an enough structural margin. The maximum structural displacement occurs at trailing edge of blade and the maximum stress occurs at the strut.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.27-36
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• 2010

It is well known that the shear strength of an RC column subjected to a lateral force decreases with the increase of the displacement ductility of column. This decreasing rate of shear strength is quite dependent on the initial shear strength. Therefore, the evaluation of the initial shear strength is important to predict the shear strength with reasonable accuracy. The shear behavior is complex because many parameters, such as the sectional shape, aspect ratio, axial force, longitudinal bars and ductility, are mutually interactive. In this study, the initial shear strength has been investigated by experiments varying parameters such as the aspect ratios, void ratios, ratio of longitudinal bars and sectional types. A new empirical equation for the initial shear strength, considering the ratio of the longitudinal bars, has been proposed and its validity has been assessed.

• Magazine of the Korea Concrete Institute
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• v.7 no.3
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• pp.139-148
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• 1995

The test results from three one fourth scale models using high strength Reinforced Concrete $f_x=704\;kg/cm^2,\;f_y=5.830\;kg/cm^2$ are presented. Such specimens are considered to represent the critical 3 storics of 60-story tall building of a structural wall system in area of high seismicity respectively. They are tested under inplane vertical and horizontal loading. The main varlable is the level of axial stress. The amounts of vertical and horizontal reinforcement are identical for the three walls testcd. The cross-section of all walls is barbell shape. The aspectratio($h_w/I_w$) of test specimen is 1.8. The aim of the study is to investigate the effects of levels of applied axial stresses on the inelastic behavior of high-strength R /C tall walls. Experimental results of high strength R /C tall walls subjected to axial load and simulated sels rnic loading show that it is possible to insure a ductlle dominant performance by promotmg flex ural yielding of vertical reinforcement and that axial stresses within $O.21f_x$ causes an increase in horizontal load-carrying capacity, initial secant st~ffness characteristics, but an decrease in displacement ductility. energy dissipation index and work damage index of high strength K /C tall walls

• 한국도로학회:학술대회논문집
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• 2006.10a
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• pp.223-228
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• 2006

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.705-714
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• 2012

Precast reinforced concrete bridge columns with hollow rectangular section were tested under cyclic lateral load with constant axial force to investigate its seismic performance. After all the precast column segments were erected, longitudinal reinforcement was inserted in the sheath prefabricated in the segments, which were then mortar grouted. Main variables of the test series were column aspect ratio, longitudinal reinforcement ratio, amount of lateral reinforcement, and location of segment joints. The aspect ratios were 4.5 and 2.5, and the longitudinal steel ratios were 1.15% and 3.07%. The amount of lateral reinforcement were 95%, 55%, 50%, and 27% of the minimum amount for full ductility design requirements in the Korean Bridge Design Code. The locations of segment joints in plastic hinge region were 0.5 and 1.0 times of the section depth from the bottom column end. The test results of cracking and failure mode, axial-flexural strength, lateral load-displacement relationship, and displacement ductility are presented. Then, safety of the ductility demand based seismic design in the Korean Bridge Design Code is discussed. The column specimens showed larger ductility than expected, because buckling of longitudinal reinforcing bar was prevented due to confinement developed not only by transverse steel but also by sheath and infilling mortar.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.8
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• pp.598-604
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• 2003

In this paper a general solution method is presented to obtain the unbalance response orbit from the finite element based equations of motion of a gear-coupled two-shaft rotor-bearing system, whose shafts rotate at their different speeds from each other. Particularly, are proposed analytical solutions of the maximum and minimum radii of the orbit. The method has been applied to analyze the unbalance response of a 800 refrigeration-ton turbo-chiller rotor-bearing system having a bull-pinion speed increasing gear. Bumps in the unbalance response of the driven high speed compressor rotor system have been observed at the first torsional natural frequency due to the coupling effect of lateral and torsional dynamics. Further, the proposed analytical solutions have agreed well with those obtained by a full numerical approach. The proposed analytical solutions can be generally applied to obtain the maximum and minimum radii of the unbalance response orbits of dual-shaft rotor-bearing systems coupled by bearings as well.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.312-317
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• 1995

씨일의 표면마찰계수 특성이 씨일의 동특성에 미치는 영향을 알아보기 위하여 씨일내의 유속이 증가함에 따라서 마찰계수가 급상승하는 허니콤 씨일을 대상으로 이론적 해석을 하였다. 그 결과 마찰계수의 급상승 현상은 마찰계수의 급상승 현상이 없는 경우에 비하여 강성계수의 감소를 야기하고 회전축-베어링계의 불안정성과 관계가 있는 연성 강성계수의 큰 감소를 보였다. 또한 회전축-베어링계의 안정성을 도모하는 감쇠 계수의 증가를 야기함으로써 회전기계의 운전점이 마찰계수의 급상승 범위에 있다면 시스템의 안정성면에서 매우 유리할 것으로 사료된다. 마찰계수의 급상승 현상을 보이는 허니콤 씨일의 동특성에 대한 이론적 해석 결과, 강성계수는 매우 작게 예측되었으나 연성강성계수와 감쇠계수는 비교적 실험결과와 근사함을 보였다.