• Journal of Korean Society of Steel Construction
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• v.15 no.5 s.66
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• pp.571-578
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• 2003

An effective seismic retrofit scheme for inverted V braced (or chevron type) steel frames was proposed by studying the redistribution of forces in the post-buckling range. The steel frames with chevron bracing are highly prone to soft story response once the compression brace buckles under earthquake loading. This paper shows that the seismic performance of such frames could be significantly improved by supplying tie bars to redistribute the inelastic deformation demand over the height of the building. A practical design method of the retrofit tie bars was also proposed by considering the sequence of buckling occurrence.

• International Journal of Highway Engineering
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• v.4 no.3 s.13
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• pp.15-23
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• 2002

The waterproofing system's performance is known to show a determing by complex interaction of material factors, design details, and the quality of construction, and the waterproofing integrity of waterproofing membranes is determined by the bond to the deck and the amount of damage to the waterproofing membrane. In this research, the basic properties of waterproofing membranes on market and the tensile adhesive chracteristics of waterproofing systems of concrete bridge deck have also been investigated in the view of the damages frequently reported from job site. For the tensile adhesive strength of sheet waterproofing membranes, the results after asphalt concrete paving tends to increase more than before those. The results of the liquid waterproofing membranes are upside-down, and the more concrete has strength, the more strength of tensile adhesive increase. The ambient temperature of asphalt concrete when application of the waterproofing membrane has considerable influence on the performance of waterproofing system. As described above, waterproofing system can be influenced by several factors. If they are not considered under construction, the overlooking will cause the damages of pavement and waterproofing system after traffic opening.

• Korean Journal of Heritage: History & Science
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• v.47 no.4
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• pp.192-209
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• 2014

The important national cultural heritages were retrieved. April 25 2014, US President Barack Obama formally returned 9 Seals of Joseon Dynasty and Korean Empire in Korea-US Summit taken place in Cheong Wa Dae. These Seals were taken out of Deoksugung illegally by a US Marine Corps officer during Korean War, handed down to his posterity, and last November 2013 confiscated by HSI in San Diego. Through investigations above facts turned out and it was decided to return these relics to Koera. In the process of surveying these seals, I confimed the authenticity of them and transferred my opinion to Cultural Heritage Administration. In this paper, I try to summarize the historical value of each Seals and suggest the remaining task.

• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.759-768
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• 2006

The turn-buckle inserted between tension members is a device adjusting a tensile force in tension member. However, the measurement of designed tensile force is impossible and the tensile force is determined based on the experience of field workers. The conventional turn-buckle might be used without any adjustment even though the tensile force has been changed for long term. To improve the disadvantages of conventional turn-buckles a turn-buckle which is measurable the tensile force is developed. In this study, the displacement to the lateral direction is induced by the deformation of curved elements if the tensile force is applied to the new type of turn-buckle that the straight elements are slightly curved. The total lateral displacement could be measured by using the micrometer or vernier-calipers. Trial devices for a measurable turn-buckle were made and tested. An theoretical study was also conducted to show the applicability, and parametric studies were conducted. The appropriate shape and capacity were determined by the parametric study.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.119-127
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• 2017

This paper presents a study of reinforced earth model wall reinforced by geosynthetics subjected to vertical surcharge. 7 types of reinforced earth model wall were constructed in the model box($100cm{\times}140cm{\times}100cm$) to assess the deformation and stress behavior of model walls according to different tensile strength and laying number of reinforcement and surcharge pressures. 3 types of geosynthetics that have different tensile strength were used as reinforcement. The test was carried out by changing the number of reinforcement to 5, 7, 9, and surcharge pressure to 50, 100, 150, 200, 250 kPa. The model test found that the maximum lateral displacements occurred at the 0.7 H (H : Wall height) position from the bottom of the model wall and vertical stress was low in the smaller surcharge pressure and the larger tensile strength of reinforcement.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.107-108
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• 2010

This paper provides test results on the tension stiffening behavior of high strength concrete (HSC) members used silica fume free binder (SFFB) instead of silica fume. The objective of this study is to evaluate the capability of replacing expensive silica fume to SFFB in HSCs with compressive strength of 60 and 80MPa. Test results indicated that for two mixes of 60 and 80 MPa HSC, cracking and strength behavior of tension members, which are replaced silica fume to SFFB, showed equivalent performance to those of tension members used silica fume.

• Composites Research
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• v.17 no.6
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• pp.1-7
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• 2004

The studies of particulate reinforced composites have been conducted for many years. The nanocomposites to be studied vigorously in recent years are one of them. We fabricated and studied multi-walled carbon nanotube(MWNT)/epoxy composites which may be useful as matrix for continuous fiber-reinforced composites. We investigated tensile properties of MWNT/epoxy composites as a function of MWNT concentration, which were prepared by the fabrication method established in this study. Tensile stiffness and strength increased 19% at 0.5 wt% and 12% at 0.2 wt%, respectively. We observed the reaggregation phenomenon of MWNTS during curing, which should be controlled to obtain higher tensile properties.

• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.575-581
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• 2001

세라믹/금속기지 복합재료에서 횡방향의 단축인장하중을 받는 경우, 복합재료의 특성에 관한 시뮬레이션 결과이다. 세라믹과 금속기지간 계면에 강한 결합이 존재하는 복합재와, 계면에서의 결합이 약한 복합재의 두 경우에 대하여 횡방향 평균응력과 평균변형율에 대한 관계를 계산하였다. 복합재료의 미시역학적개념과 유한요소해석법을 적용하여 세라믹체적분율의 변화에 따라 각기 해석되었다. 본 연구에서 계산된 횡방향 탄성계수는 문헌에 알려져 있는 미시역학개념으로 유도된 식에 의한 횡방향탄성계수값과 잘 일치되었다. 계면에서 강한 결합이 있는 복합재와는 달리, 약한 결합의 복합재는 인장하중에 의하여 세라믹/금속계면에서 금속재료와 세라믹간의 분리가 발생된다. 이 분리는 전체복합재의 강성을 감소시키며, 금속의 부피분율이 감소될수록 (즉, 세라믹의 부피분율이 증가할수록) 횡방향 평균응력의 평균변형율에 대한 감소로 나타났다. 미시역학의 개념을 적용한 유한요소해석기법을 통하여, 이미 알고 있는 복합재 각 성분의 특성으로부터 복합재료의 계면특성과 횡방향특성을 예측할 수 있다.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.20-28
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• 1997

용접부에는 많은 취약조건들이 존재하며 파괴의 주 원인이 되고 있어 이들에 대한 많은 연구가 진행되고 있다. 따라서, 현재 용접재료, 용접 조건 및 용접방법 등 을 개선함으로써 여러 방면에서 좋은 결과를 얻고 있다. 그러나 아직도 용접시의 열소 성변형과 구속조건에 따라 분포하는 잔류응력에 의한 피로균열거동에 대한 연구는 정확한 잔류응력 측정의 어려움으로 미흡한 상태이다. 특히 잔류응력의 측정기술과 반복하중에 의한 피로균열 진전시 잔류응력의 이완 등은 이들을 해석하는데 많은 어 려움을 주고 있다. 용접시 높은 열에 의한 재료의 팽창과 냉각시의 수축변형은 용접 부재에 인장 및 압축 잔류응력을 유발시키고, 인장잔류응력은 균열 진전될 때 잔류 응력은 오히려 균열을 지연시키기도 한다. 또한 잔류응력장에서 피로 균열이 진전될 때 잔류응력은 일반적으로 작용하중의 크기와 반복 수 그리고 균열 진전 등으로 인하 여 이완되고 재분포된다. 본 해설에서는 용접재의 피로거동중에 발생하는 잔류응력의 재분포 현상을 하중의 범위, 하중 반복수, 균열 진전의 영향으로 구분하여 각각의 영향에 대해서 기술하고자 한다.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.87-95
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• 2003

In this paper, the discrete element method was applied to evaluate the stability of composite cover and lining system of landfill. This method is capable of estimating the distribution of tensile force and shear stress mobilized in each liner component and its interfaces, based on a relationship of force and displacement. It was assumed that the cover soil and geomembrane were comprised of slices connected with elastoplastic Winkler springs and tensile spring respectively. Parametric study using this method was performed and compared with other techniques based on limit equilibrium method fur the example analysis.