• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.287-295
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• 2010

The main purpose of this study is to investigate the static behavior of spliced prestressed concrete girder with bending moment connector and lateral prestressing. Four (4) spliced girders and one (1) monolithic girder had been fabricated and tested to compare their static behaviors. Same geometry and materials are used to fabricate these spliced and monolithic girders. A monolithic girder and one (1) spliced girder without lateral bending connector are used as control specimens to estimate the performance of three (3) spliced girders with lateral bending connector. Deflections at the middle of girders have been measured for evaluation. Also, strains of the concrete at the middle of span and connection points have been measured. It was found from the result that laterally strengthened spliced girders showed improved ultimate strength but less stiffness compared to the monolithic girder at the ultimate state. Laterally strengthened spliced girder also showed improved strength as well as improved stiffness compared to the spliced girder without lateral strengthening.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.483-486
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• 2005

The polymer concrete is drawing a strong interest as high-performance materials in the construction industry. Resins using recycled PET offer the possibility of a lower source cost of materials for making useful polymer concrete products. Also the recycling of PET in polymer concrete would help solve some of the solid waste problems posed by plastics and save energy. Polymer concrete beams using unsaturated polyester resins based on recycled polyethylene terephthalate (PET) plastic waste were used in our study for grasping its structural behavior of static and fatigue. As a result of static test, Compression stress distribution of Polymer concrete indicates linear behavior such as triangles. Although polymer concrete is high strength materials, its ductility capacity is excellent. From the fatigue test results, There was almost no difference on flexural characteristics between before and after fatigue loading. Therefore, recycled PET polymer concrete remains excellent structural ability after fatigue loading.

• Journal of the Korean GEO-environmental Society
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• v.3 no.2
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• pp.61-70
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• 2002

This paper presents the engineering property of light weight soil made of soil mixed with recycled Styrofoam and stabilizer. Recycled Styrofoam is widely used for lightweight fill material because it has important geotechnical characteristics which are light, adiabatic, and effective for vibration interception. It is very easy to get the disposal styrofoam. For this study, dynamic compaction test, static compaction test and pH and leaching tests were performed. Based on the test results, it is concluded that the static compaction method is recommened to prevent from crushing materials and pH values of embankment materials are satisfied with these of domestic and RCRA configuration.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.3
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• pp.265-275
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• 2005

The objective of this paper is to numerically assess the behavior of tubular X-joints with an internal ing stiffener, and to evaluate the reinforcement effect of a ring stiffener, and to establish the strength formulae. Nonlinear finite element analysis is used to compute the static strength of axially loaded tubular joints. Numerical and experimental results are in good agreement for tubular X-joints. The chord lengths of simple and ring-stiffened X-joints are suggested to reduce chord end effect. And, internal ring stiffener is found to be efficient In improving static strength of tubular X-joints. Maximum strength ratios are calculated as $1.5\sim3.5$. Regression analyses are performed considering practical size of ring stiffener and strength estimation formulae for tubular X-joints with an internal ring stiffener are proposed.

• Tunnel and Underground Space
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• v.31 no.6
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• pp.561-577
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• 2021

The compacted bentonite buffer in a geological repository for high-level radioactive waste disposal is saturated due to groundwater inflow. Saturation of the bentonite buffer results in bentonite swelling and bentonite penetration into the rock discontinuities present around the disposal hole. The penetrated bentonite is exposed to groundwater flow and can be eroded out of the repository, resulting in bentonite mass loss which can affect the physical integrity of the engineered barrier system. Hence, the evaluation of buffer-rock interactions and coupled behavior due to groundwater inflow and bentonite penetration is necessary to ensure long-term disposal safety. In this study, the effects of the bentonite penetration and swelling on the physical properties of jointed rock mass were evaluated using the quasi-static resonant column test. Jointed rock specimens with bentonite penetration were manufactured using Gyeongju bentonite and hollow cylindrical granite rock discs obtained from the KAERI underground research tunnel. The effects of vertical stress and saturation were assessed using the P-wave and S-wave velocities for intact rock, jointed rock and jointed rock with bentonite penetration specimens. The joint normal and joint shear stiffnesses of each joint condition were inferred from the wave velocity results assuming an equivalent continuum. The joint normal and joint shear stiffnesses obtained from this study can be used as input factors for future numerical analysis on the performance evaluation of geological waste disposal considering rock discontinuities.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05a
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• pp.469-474
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• 1998

이상 유동 지배 방정식에 두 상의 경계면 두께 개념을 도입하여 액체 내부에서의 기포 거동에 대한 동적 안정성을 이론적으로 해석하였다. 현재까지 기포의 안정성은 실험과 거시적인 물리적 이론에 의하여만 정적으로 연구되어 왔으나, 상간의 압력 불연속성을 표면장력 모델링을 이용하여 해석적으로 해결 함으로서 기포 안정성에 대한 정량적인 분석을 가능하게 하였다. 그 결과 기포의 안정성은 기존의 무차윈 Weber수 이외에 Reynolds수 그리고 유체의 점성력과 Capillary파와 관련된 무차원 수에 의해서도 영향을 받는 것으로 밝혀졌다.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.2
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• pp.135-140
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• 2016

Corrective controllers enable fault diagnosis and tolerance for various faults in asynchronous sequential circuits without resort to redesign. In this paper, we propose a static corrective controller in order to decrease the size of the controller. Compared with dynamic controllers, static controllers can be made using only combinational circuits, as they need no inner states. We address the existence condition and design procedures for static corrective controllers that overcome state transition faults. To show the validity and advantage, the proposed controller is applied to an SEU error counter implemented on FPGA.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.735-750
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• 1991

본 연구에서는 적층 복합판의 충격 해석을 위하여 Reddy의 고차 전단 변형 이 론에 기초를 두고, 정적 압입 실험에 의한 접촉 법칙을 고려한 동적 유한 요소 해석 (dynamic finite element analysis)을 행하여 충격 실험에 의한 결과와 1차 전단변형 이론에 의한 해와 비교 검토하므로서, 그 유용성과 우수성을 입증하고, 적층 복합재의 충격 응력 및 응력파 전파 특성에 대하여 연구하고자 한다.

• Journal of Korean Society of Steel Construction
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• v.28 no.3
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• pp.139-149
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• 2016

Roof cladding of buildings are required for the measures about the 'screw pull-out' which causes the casualties and the property damage by typhoons. In this study, the pull-out resistance was increased by increasing the penetration depth of the screw installing a ironware called 'insert nut' on the roof cladding frame. Tensile tests were conducted to compare the pull-out strengths of a general screw-joint and a nut insert joint. Roof cladding that is actually being used in the field was produced using the 'solid work' and then the roof claddings using a general screw-joint and a nut insert joint were compared by a static test and dynamic test.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.160-163
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• 1995

본 硏究는 現在 일상적 있는 재생조골재를 죠오크러져(modified-jaw crusher)를 이 용하여 다시 1-3 파쇄를 행함으로써 재생골재의 품질이 어느정도 개량될 수 있는가를 실험 적으로 구명하여 재생골재의 실용화를 위한 하나의 방법을 제한하고자 하는 것이다. 실험결 과,재화파생 처리를 행하지 않은 경우의 재생근 골재의 흡수율은 5-7%정도이나 재파쇄를 함에 따라 흡수율은 현저하게 낮아져, 3차례의 재파쇄를 행한 경우 흡수율이 2% 이래로 나 타나 재생근골재의 품질을 학보하기 위하여는 재파쇄가 매우 유용한 방법임을 알 수 있었 다. 또한 흡수율의 본포도 처음에는 2개의 범주를 가지고 넓게 산포하게 되나 재파쇄가 진 행될수록 재생근골재중에 부착되어 있던 모르터분이 점차 떨어져 나감에 따라 품질의 산포 가 상당히 낮아지는 결과를 얻었다. 그러나 이와같은 재파쇄에는 많은 실용적 부담이 발생 하게 되므로 골재의 품질과 경제적효율을 고려하여 정적한 재파쇄회수가 결정되어야 할 것 으로 사료 된다.