• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.391-400
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• 1997

The objective of this paper is to suggest formula of Concrete Filled Tube Beam-Column members maximum strength by using of numerical analysis and tests. The numerical analysis results are compared with test results for evaluating numerical analysis method. The formula of Limit State Design of Architectural Institute of KOREA is used for basic form of suggestion formula. In order to suggest formula, two methods are used. One is to use the coefficient, and the other is to use the amplified factor of material strength. The formula by two methods are compared with numerical analysis results.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.95-100
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• 1996

This paper presents the experimental study on hardening process of high-strength and high-flowable concrete. The experiments were performed to investigate any unfavorable construction situations since the actual concrete placement has been scheduled in cold weather period, so that the high quality concrete construction is convinced to be successfully carried out. The tests were conducted using 600nm and 1000nm height of steel tube to simulate the practical concrete filled steel tube columns according to the following variables as: the categories of chemical admixtures, curing temperatures and curing schemes. The test results were analyzed in terms of hardening speed, internal heat of hydration and history of strength gain. This paper emphasizes the importance of curing schemes on durability and the use of hardening accelerators on strength gain.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.1023-1028
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• 2003

The structure of Tower Palace III Sports Center building was designed as concrete Filled Steel Tube(CFT) Column and the filled-in concrete was designed as high compressive strength of 500kgf/$m_2$. The self compacting concrete(SCC, non-vibrating concrete) with 65$\pm$5cm flow must be applied to this case for filling the CFT by injecting the concrete from the column bottom. Laboratory tests and pilot productions of batcher plant were performed for optimum mix design and the full scale Mock-Up test was performed to check the appicability of the construction method. As a result, we observed that good quality SCC and the pressure change of concrete pump normally used domestically. Based on these results, we have constructed 20-40m height CFT columns successfully.

• Magazine of the Korea Concrete Institute
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• v.14 no.6
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• pp.88-95
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• 2002

최근 국내에 60층을 초과하는 초고층 구조물들이 많이 건설되고 있으며, 콘크리트 품질의 향상 특히 콘크리트의 고강도화에 힘입어 이를 이용한 철근 콘크리트 고층 구조물들이 증가하고 있다. 이에 따라 이들 초고층, 초대형 구조물을 지지할 수 있는 고축력, 고연성의 기둥에 대한 설계 및 시공이 요구되고 있으며, 이에 가장 적합한 구조요소라 할 수 있는 콘크리트 충전 강관기둥(Concrete Filled Steel Tube Columns : CFT Columns)의 설계 및 시공에 관심이 높아지고 있다. 이러한 콘크리트 충전 강관기둥은 콘크리트가 강관에 의해 둘러싸여지기 때문에 축하중 저항 능력이 증가되는 장점과 동일한 단면으로 H형강을 사용한 순수 철골조 H형강 기둥의 강축(strong axis)과 약축(weak axis) 문제해결과 동시에 강성 (stiffness)을 증가시킬 수 있으며, 내화 성능이 향상되고 거푸집 대체 재료로 사용되는 등 여러 가지 장점을 지니고 있다. 한편 충전 강관기둥에 작용하는 축하중은 대부분 콘크리트가 부담하게 되는데 이러한 충전강관 기둥의 장점을 극대화하기 위해서는 보통강도 콘크리트보다는 압축강도 및 탄성계수가 큰 고강도 콘크리트의 사용은 불가피하게 된다.(중략)

• Smart Structures and Systems
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• v.19 no.4
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• pp.415-429
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• 2017

This paper focuses on the impact of the wave passage effect on the long-span bridge. In order to make the wave passage effect more obvious, ground motion samples are selected from the near-fault ground motion of the 1999 Chi-Chi earthquake and an arch bridge with a 280m main span is selected as a bridge sample. The motion ground samples are divided into two groups according to the characteristics of near-fault. A sequence of fragility curves is developed. It is shown that the seismic damage is increased by the wave passage effect and the increase is more obvious in the near-fault ground motion.

• Structural Engineering and Mechanics
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• v.76 no.1
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• pp.101-114
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• 2020

In this paper, an improved experience-based learning algorithm (EBL), termed as IEBL, is proposed to solve the nonlinear hysteretic parameter identification problem with Bouc-Wen model. A quasi-opposition-based learning mechanism and new updating equations are introduced to improve both the exploration and exploitation abilities of the algorithm. Numerical studies on a single-degree-of-freedom system without/with viscous damping are conducted to investigate the efficiency and robustness of the proposed algorithm. A laboratory test of seven lead-filled steel tube dampers is presented and their hysteretic parameters are also successfully identified with normalized mean square error values less than 2.97%. Both numerical and laboratory results confirm that, in comparison with EBL, CMFOA, SSA, and Jaya, the IEBL is superior in nonlinear hysteretic parameter identification in terms of convergence and accuracy even under measurement noise.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.788-793
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• 2001

Finite element analysis was carried out to investigate the integrity and reliability of boiler module during sea transportation. The boiler module was supported by steel structure to relieve the instantaneous shock from oceanic wave and its primary parts were strengthened with several reinforcements. Finned tube walls which were used in the furnace wall were assumed as orthotropic plates having equivalent material properties. The bank tubes were also equivalently modeled in accordance with ASME B31.1 for the convenience of finite element modeling. The calculation results were compared with the yield stress of the material. In particular, the bank tube stress, which was evaluated by converting the calculated stresses in equivalent tubes into those in original tubes by using the ratio of diameter, was also examined with yield stress.

• Journal of the Korea Institute of Building Construction
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• v.2 no.1
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• pp.163-169
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• 2002

In this study, there are kind of property experiments like fluidity, compressive strength, bleeding measurement, concrete sink for CFT use high fluidity concrete. The property difference between before transmit and after transmit concrete in the mock up test with ready mixed concrete equipment is examined. The variable factors in mock up are diaphragm existence and nonexistence, diaphragm placing hole sizes. To investing the concrete Property under diaphragm, concrete packing ability, hydration heat, core specimen strength tests are performed.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.151-157
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• 2004

In this paper deals with behavior of the magnetic abrasive using sludge on polishing characteristics in a new internal finishing of seamless stainless steel tube applying magnetic abrasive polishing. The magnetic abrasive using sludge-abrasive grain WA and GC used to resin bond fabricated low temperature. And sludge of magnetic abrasive powder fabricated that sludge was crused into 200 mesh. The previous research have made an experiment in the static state the movement of magnetic abrasive grain is nevertheless in the dynamic state. In this paper, We could have investigated into the changes of the movement of magnetic abrasive grain. In reference to this result, we could have made the experiment which is set under the condition of the magnetic flux density, polishing velocity according to the form of magnetic brush.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.419-422
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• 2005

Prestressed composite girder bridges with concrete infilled steel tube at negative flexural moment region takes the advantages provided due to the interactive reaction in the steel tube and concrete interface layer, enhancing local buckling resistance and the concrete strength provided by the lateral confining effect of concrete. Two beams were tested to examine ultimate behaviors of prestressed composite girder bridges subjected to negative flexural moment. The experimental observations of the Prestressed composite girder bridges subjected to positive flexural moment are investigated and compared to the numerical results obtained by sectional analysis method, and 1-D. and 3-D. finite element analysis methods.