• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.143-146
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• 2005

최근 들어 90도 표준갈고리의 대안으로 정착판을 지니는 헤드 철근(headed bar)에 대한 관심이 높아지고 있다. 헤드 철근의 정착내력은, 정착판의 지압력과 위험단면에서 헤드까지 정착길이의 부착력으로 발현된다. 실제 구조물에서는 정착되는 부재의 재료 및 기하학적 물성에 의해 다양한 파괴가 발생된다. 따라서 헤드 철근의 정착내력은 단순히 지압력과 부착력의 합으로 산정될 수 없으며, 발생 가능한 모든 파괴양상을 고려한 최소 내력으로 결정되어야 한다. 헤드 철근의 정착내력을 산정하기 위한 기본적인 해석모델로, CCT 절점에 정착된 헤드 철근의 트러스 모델을 제안하였다. 제안된 트러스 모델의 파괴는 부착파괴와 콘크리트의 압축파괴로 구분되며, 재료 및 기하학적 물성에 의해 파괴 양상이 결정된다. 이러한 트러스 모델은 외부 보-기둥 접합부와 같이 보다 복잡한 부위에 정착된 헤드철근의 정착 기구를 설명하는데 활용될 수 있다.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.623-626
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• 2004

The purpose of this paper is to study the effect of longitudinal reinforcement for anchoring in the wide beam column joint as wall as the contribution of depth of spandrel beam to hysteretic behavior of the wide beam column joint. From the test it was shown that the specimen with anchorage in the joint had higher strength than the specimen with normal hook anchorage. Specimen with debonded reinforcement at out of Id from column face failed showing moved plastic hinge and less strength than normal specimen. However, the dissipated energy was increased $11\%$.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.343-350
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• 1999

The purpose of this study is to compare the response of the high-strength concrete beam-column-slab subassembly with the response of a normal-strength concrete specimens. Four assemblies were designed 2/3 scale beam-column-slab joint(fc'=240kg/cm2 fc'=700kg/cm2) and tested to investigate seismic behaviour. From the test results 1) flexral cracks emerge to inside of bean deeply for high strength concrete member 2) the high-strength specimens represented stable hysteretic behaviour for the displacement ductility 5.5 but degradation in stiffness and strength and unstable hysteretic behaviors were observed owing to the brittleness of high-strength concrete beyond its range.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.199-204
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• 2003

The purpose of this study is to experimentally investigate the structural performance of concrete exterior beam-column joints confined by carbon sheet tube. Four specimens were produced with different numbers of carbon sheet and the other specimen was produced with reinforced concrete. A hydraulic dynamic actuator with 30tonf capacity was used to cyclic lateral loading test. The experimental results represent that the numbers of carbon sheet have an influence the load and displacement capacity. However, the bond length of carbon sheets for connecting beam and column has to be considered to improve the capacity of joint.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.305-308
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• 2005

This paper presents a fabrication of a full-stale combustion chamber of a liquid rocket engine for a ground hot firing test. Engine drawings for manufacturing were prepared after conceptual and detail designs. The combustor is composed of a head and a chamber. SUS316L is used for materials of the head because of the good quality in low temperature. Inner materials of the ablative cooling chamber is silica/phenolic and outer case materials is the SUS316L. Materials of the regenerative cooling chamber are C18200 and SUS316L. After lathe, general milling and MCT machinings, components were finished by electrolytic polishing. A brazing method was applied for bonding the injectors and the injector plate, the regenerative cooling chamber because of structure configurations.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.451-458
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• 2015

The infill-wall strengthening method has been widely used for the seismic performance enhancement of the conventional reinforced concrete (RC) frame structures with non-seismic detail, which is one of the promising techniques to secure the high resisting capacity against lateral forces induced by earthquake. During the application of the infill-wall strengthening method, however, it often restricts the use of the structure. In addition, it is difficult to cast the connection part between the wall and the frame, and also difficult to ensure the shear resistance performances along the connection. In this study, an advanced strengthening method using the externally-anchored precast wall-panel (EPCW) was proposed to overcome the disadvantages of the conventional infill-wall strengthening method. The one-third scaled four RC frame specimens were fabricated, and the cyclic loading tests were conducted to verify the EPCW strengthening method. The test results showed that the strength, lateral stiffness, energy dissipation capacity of the RC frame structures strengthened by the proposed EPCW method were significantly improved compared to the control test specimen.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.307-315
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• 2008

Post-tensioned precast concrete system (PPS) consists of U-shaped precast wide beams and concrete column. The continuity of beam-column joint is provided with the topping concrete on the PC shell beam and post-tensioning. Nonlinear analysis was conducted, using ANSYS, a finite-element analysis program, to obtain data for determining the characteristics of the structure and to allow various parametric analyses for post-tensioned wide beam-column connections. In this analysis, the Solid 65 element was used, in which concrete element had 8 nodes and each node had 3 degrees of freedomIn. Solid 65, the shear-transfer factor reflects a decrease of shear strength for the positions with cracks, as an impact factor to make the analysis value approximate the experiment value. In this study, the behavior of test specineus were most closely predicted to the experimental results, when the shear-transfer coefficient 0.85 was used for a closed crack, and 0.2 was used for an open crack.

• Conservation Science in Museum
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• v.10
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• pp.21-27
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• 2009

This bamboo brush stand was made by attaching two bamboo tubes together, each 80mm in diameter. On the bottom is a "∞-shaped"wood board made of Ailanthus altissima. The surfaces are decorated with exquisite and dynamic designs of a dragon and clouds, and a deer and pine trees. Part of this bamboo brush stand was damaged, lost, or worn down, prior to conservation treatment. After conservation and recovery treatment, its original form was restored. Earth powder, chalk, and gluten mixture were used as materials to fill in the missing parts. After the original form was restored, thin silk fabric was attached to the inner surface of the glued part to prevent cracking. Traditional materials and repair techniques were used to allow for reversal of treatment, if necessary, as seen in the surface of the restored part being made antiquated with lacquer varnish.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.91-95
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• 2012

본 연구에서는 열충격 시험을 통하여 Cell레벨에서의 효율저하 특성을 분석하였다. 열충격 시험은 PV모듈의 시험 규격인 KS C IEC-61215를 이용하여 보다 가혹한 조건인 $-40^{\circ}C$에서 $120^{\circ}C$의 조건으로 500사이클 수행하였다. I-V 측정을 통하여 효율을 분석한 결과, 열충격 시험 전 13.9%에서 열충격 시험 후 11.0%로 효율이 저하 됐으며, 감소율은 20.9% 나타났다.EL촬영을 통해 표면을 분석한 결과 Ribbon접합부 및 Gridfinger의 손상으로 확인 됐으며, 보다 정확한 효율 저하의 원인을 분석하기 위해 단면분석을 실시한 결과 표면손상으로 확인 되었던 위치의 Cell내부에서도 Crack을 확인 할 수 있었다. 또한 FF값을 분석한 결과 열충격 시험 전 72.3%에서 시험 후 62.0%로 11.8%의 감소율을 보였다. 따라서, 경년 시 나타나는 효율저하는 Cell자체의 소모전력 증가와 외부환경에 의한 표면 손상 및 Cell내부의 Crack에 기인하여 가속된다고 판단된다.

• Journal of Welding and Joining
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• v.19 no.3
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• pp.285-291
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• 2001

Large steel water pipes are joined prevalently by the bell end method, and are welded both at inside and outside of lapped parts. In practice, welded joints of water pipes are very critical, because in most cases failure of pipes causing leakage occurs at the welded joint. Therefore some methods have been developed to ensure the soundness of welded joints of water pipes, like leakage tests and nondestructive tests (NDTs). But one of the major characteristics that affects the soundness of welded Joints is the stress distribution caused by welding and external forces. Some studies have been carried out on the residual stress of steel water popes, but complex stress distributions by welding and external forces are rarely studied. In this study, temperature and stress distributions in steel water pipes produced by welding are predicted by a three-dimensional finite element method(FEM). Also, stress values are measured from real steel water pipes by the hole-drilling methods, and compared with predicted ones. The influence of some typical post weld treatments on residual stress distribution was also investigated by residual stress measurements.