• Journal of Korean Society of Steel Construction
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• v.11 no.1 s.38
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• pp.89-98
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• 1999

The objective of this paper is to investigate the structural behavior of concrete filled steel tubular columns subjected to eccentric load. With experiment and analytical study, the buckling behavior of columns is investigated and compared with each other to the view of main parameters. Appling foreign standards in the experimental results, we suggested new strength formula of concrete-filled steel tubular columns. The parameters are slenderness, eccentric ratio, and concrete filled or not. The experiment are carried out by simple loading.

• Journal of Korean Society of Steel Construction
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• v.12 no.4 s.47
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• pp.387-395
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• 2000

The purpose of this research is to evaluate the capacity of strength and plastic deformation of those members, and provide experimental data on the seismic behavior of these members as a basis for developing guidelines for designing seismically resistant concrete-filled steel tubular columns. Eighteen cantilever-type specimens were tested under constant axial load and cyclically lateral load as models of bottom columns in high-rise building. The parameters studied in the test program included, are width-thickness ratio of steel tube, slenderness ratio (Lo/D) and axial force ratio. From the test results, the effects of parameters on the strength, the deformation capacity, energy absorption capacity are discussed. The specimen flexural capacity under combined axial and lateral loading was found to be almost accurately predicted by criteria AIJ and AISC-LRFD providing conservative results. Therefore KSSC for encased composite column can be applied to the concrete filled column if composite section and elastic modulus are modified according to AIJ and AISC-LRFD. Finally, the proposed flexural capacity considering confinement effects is a food agreement on the tests results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.176-182
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• 2018

The purpose of this study was to investigate the safety and rationality of buckling strength and length coefficient by comparing with the design standards of domestic and foreign compression materials based on the buckling test results of circular steel pipe with ball joints. The types of round steel pipes selected for buckling performance evaluation were ø$48.6{\times}2.8t$, ø$60.5{\times}3.2t$ and ø$76.3{\times}3.2t$. For the design of domestic and foreign compression materials, Korea 's Load Resistance and Factor Design, Japan' s Limit State Design, and British Standard BS5950 standard were applied. In this study, we compared and analyzed the buckling performance between the experimental results of the previous research and the domestic and foreign design standards. The results were summarized as follows. As a result of applying the full length of the member to the buckling length in the compression materials design standards of each country, it was 64-89% of the buckling strength by the experiment. Therefore, it is deemed desirable to perform the member design according to the current design standard formula for safety. Experimental results show that the measured buckling strength was 1.02-1.43 times higher than the buckling strength of pure cylindrical steel tubes in the design standards of Korea, Japan and the United Kingdom compression materials. Consequently, it seemed that the buckling strength of individual member in the design of space frame structure should be considered buckling coefficient as the length of pure round steel pipe rather than the length of inter-node.

• The Korean Journal of Financial Studies
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• v.9 no.1
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• pp.37-67
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• 2003

현재 기업지배구조의 개선은 OECD 및 세계은행, CalPERS 등의 국제기관투자자는 물론이고 각국정부의 주요 과제로 등장하고 있다. 한국의 경우 기업지배구조의 개선이 핵심적인 경제이슈로 부각된 것은 1997년말에 닥친 외환위기와 극심한 불황을 당하고 나서라고 할 수 있다. 그후 외환위기의 극복과정에서 기업지배구조 모범규준 제정, 이사회 및 감사기구의 강화, 소수주주의 권한 강화, 기관투자자(외국인투자자 포함) 및 시민단체의 활동강화, 기업지배권 시장의 활성화 등 주로 정부주도에 의한 제도변화가 급속하게 도입 시행되었다. 일본의 경우에는 기업지배구조 개선에 대한 공식적인 논의는 한국보다 앞섰으나 제도의 도입과 실행은 한국에 비하여 상당히 늦었다. 2001년 12월의 상법개정에서 감사역의 독립성 강화, 사외감사역 제도의 충실화, 취체역의 책임경감, 주주대표 소송의 합리화 등 비교적 큰 폭의 제도개선이 이루어졌다. 그러나 사외이사를 중심으로 하는 미국식 이사회 제도의 채택은 향후의 개혁방향에 포함되어 있다.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.671-682
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• 2004

This study investigated the effects of a shear slip on the deflection of steel-concretecomposite beams with partial shear interaction. Under the guidance of various current design codes, this deflection was related to the strength of shear connectors in the composite beams. In this paper, a shear connector stiffness based on exact solutions, regardless of loading conditions, was developed. The equivalent rigidity of composite beams that considered three different loading types was first derived, based on equilibrium and curvature compatibility, from which a general formula accounting for slips was developed. To validate this approach, the predicted maximum deflection under the proposed method was compared against currently used equations to calculate beam effective stiffness (AISC)Nie's equations, which have recently been proposed. For typical beams that were used in practice, shear slips might result in stiffness reduction of up to 18% for short-span beams. For full composite sections, the effective section modulus with the AISC specifications was larger than that of the present study, which meant that the specifications were not conservative. For partial composite sections, the AISC predictions were more conservative than those in the present study.