• Proceedings of the KSR Conference
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• 2007.11a
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• pp.517-528
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• 2007

Domestic or international existing researches regarding rail damage factors are focused on laying, vehicle conditions, driving speed and driving habits and overlook characteristics of track structure (elasticity, maintenance etc). Also in ballast track, as there is no special lateral spring stiffness of track also called as ballast lateral resistance in concrete track, generally, existing study shows concrete track has 2 time shorter life cycle for rail replacement than ballast track due to abrasion. As a result of domestic concrete track design and operation performance review, concrete track elasticity is lower than track elasticity of ballast track resulting higher damage on rail and tracks. Generally, concrete track has advantage in track elasticity adjustment than ballast track and in case of Europe, in concrete track design, it is recommended to have same or higher performance range of vertical elastic stiffness of ballast track but domestically or internationally review on lateral spring stiffness of track is very minimal. Therefore, through analysis of service line track on site measurement and analysis on performance of maintenance, in this research, dynamic characteristic behaviors of commonly used ballast and concrete track are studied to infer elasticity of service line track and experimentally prove effects of track lateral spring stiffness that influence curved rail damage as well as correlation between track elasticity by track system and rail damage to propose importance of appropriate elastic stiffness level for concrete and ballast track.

• Journal of the Korea Concrete Institute
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• v.26 no.1
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• pp.47-55
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• 2014

As increasing number of large-size earthquake around Korean peninsula, many interests have been focused to the earthquake strengthening of existing structures. The brittle fracture of Non-seismic designed columns lead to full collapse of the building. In the past, cross-sectional extension method, a steel plate reinforcing method and fiver-reinforced method are applied to Seismic Rehabilitation Technique mainly. However, the reinforcement methods have drawbacks that induce physical damage to structures, large space, long duration time. So, in this study, performance evaluation of previously developed FRP seismic reinforcement which do not induce physical damage and short duration time was enforced. The specimens were constructed with 80% downscale. FRP seismic reinforcement are manufactured of glass fiber or aluminum plate with holes and glass fiber. From the experiment results, seismic performance of specimens which reinforced with FRP seismic reinforcement were increased.

• Fire Science and Engineering
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• v.26 no.6
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• pp.72-77
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• 2012

When the concrete and steel combined composite beam is exposed to high temperature, concrete could delay temperature rising of steel by covering or increase heat capacity of structural member. For becoming of structural reinforcing by unification between materials, fire resistance rate of composite beam would be higher than simple steel beam. The temperature rising of exposed steel of composite beam is directly related with section shape and exposure length of steel. In this study, fire resistant tests were carried out for composite beams and steel beam with same thickness of spray-type fire resistant materials in standard fire, and after that, temperature histories were analysed and compared with shape factor. The correlation between steel temperature and shape factor was showed very high. This result suggests that if it can be predict the comparative advantage of member by factor which cause the performance enhancement, it could be conclude that an Standard Accreditation method can be adjust to members without indivisual certifiicate of accreditation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.135-136
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• 2016

SUPER concrete poontoon is developed to overcome shortcomings about corrosion problem of steel pontoon and the insufficient freeboard line of concrete pontoon. Top slab of Pontoon resists truck load or sidewalk live load. The soffit slab and outer wall of Pontoon resist the horizontal and vertical components of wave pressure, and those were loaded along X and Y-axis of Pontoon. Global analysis for the Pontoon is carried out to design its cross-sections economically using a geometric non-linear time history analysis method by Strand7 and buoyance-stability calculated automatically on non-vertical boundary conditions. And the load-capacity of Pontoon is confirmed through mock-up tests.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.90-90
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• 2011

최근 전 세계적으로 지진의 발생 빈도가 증가하며 그 규모도 점차 커지는 경향을 보이고 있다. 대형지진의 발생 시 저층 구조물의 붕괴로 인한 인명 및 사회, 경제적 피해가 두드러짐에 따라 기존 저층 구조물의 내진보강기법에 관한 연구가 활발히 진행 중인 추세이다. 우리나라의 경우 강도증가형 내진보강공법이 주를 이루고 있어 다양한 내진보강기법의 개발 및 적용이 필요한 실정이다. 따라서 본 연구에서는 지진입력하중 저감형 내진보강기법으로서 강재댐퍼시스템을 제안하여 구조적 성능을 파악하고, 이를 적용한 보강 실험체와 비보강 실험체를 제작하여 정적가력실험을 통하여 그 성능을 비교하였다. 제안된 강재댐퍼시스템은 입력에너지를 소산시키는 내부의 슬릿형 댐퍼와 이를 지지하는 기둥 및 외부 프레임으로 구성되며, 내부 댐퍼는 먼저 항복하여 에너지를 소산시키기 위하여 지지기둥 및 프레임에 사용된 강재보다 강성 및 강도가 적게 계획되었다. 강재댐퍼의 성능실험 결과, 비교적 안정적 거동을 하며, 강성과 강도 및 에너지 흡수능력이 우수하게 나타났다. 보강 및 비보강 실험체의 골조는 기존 학교 건축물의 표준도면을 기준으로 하여 골조의 일부를 대상으로 60% 축소율을 적용하여 계획하였으며, 보강 실험체는 미리 제작된 강재댐퍼시스템을 골조 내에 설치하여 에폭시 주입법으로 부착시공 하였다. 보강 및 비보강 골조 실험체의 정적가력 실험결과 비보강 실험체는 기둥의 휨 항복 후 변형의 증가에 따라 휨 및 전단 균열이 증가하면서 최종적으로 기둥이 전단파괴 되었으며, 보강 실험체는 비보강 실험체에 비하여 기둥 및 보의 균열이 적고, 골조에 골고루 분포되어 파괴 규모가 감소하였다. 최대 강도면에서 보강 실험체는 비보강 실험체에 비하여 약 3.4배 우수하였으며, 초기강성은 약 7배 가량 유리한 것으로 평가되어 제안된 강재댐퍼시스템이 강도면에서 우수한 성능을 나타냄을 알 수 있었다. 또한 두 실험체의 기둥 주근 및 띠철근의 변형률을 비교한 결과, 비보강 실험체는 대부분의 철근이 항복하여 큰 변형을 일으킨 반면, 보강실험체에서는 철근의 항복현상이 나타나지 않았고 댐퍼가 항복을 하면서 큰 변형을 일으켰다. 이를 통해 지진하중 입력 시 댐퍼에서 입력 에너지를 흡수하여 큰 하중을 부담하며, 기존의 구조부재에는 입력 에너지가 낮아 손상이 보다 적게 발생함을 확인하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.579-585
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• 2017

Development of a facade system that can reduce load factor and costs in high-rise building construction is required. The proposed cable wall system is used as a structural support by the glass-cable and can increase openness on lower elevations and the lobby area. Its use in high-rise buildings can reduce construction costs. Without transferring directly a strong initial tension of the cable to the building frame is connected to the steel member and the reinforced concrete structures, by absorbing the initial tension of the cable, it is possible to control the occurrence of a strong concentrated loads to the structure. Comparison of load-displacement test results from the numerical analysis with the test results showed reasonable agreement, Therefore, the proposed numerical results confirm good prediction of cable behavior for the facade system.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.95-103
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• 2009

Deformations of bridge deck ends on abutments and piers bring about severe problems in track geometry and require maintenance work. In case of concrete slab track, more severe deformation and additional forces on rail and rail supports can be induced by bridge deck deformation, which affect the serviceability of track structure since concrete slab track is much stiffer than ballasted track and the behavior of track structure is integrated with that of bridge deck. In this study, the design variables affecting the serviceability of track structure are selected and the influence level is estimated by a parametric study. As a result, it is found that continuous span is advantageous than simply supported span and the stiffness of bridge bearing and rail fastener as well as the distance between last rail support and bridge bearing are most important parameters.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.479-485
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• 2016

This paper presents an experimental study conducted to investigate the effect of recycled fine aggregate (RFA) on the mechanical properties and chloride diffusion behavior of mortar. The test results revealed that the addition of RFA plays an important role in the mechanical properties and pore structures of the investigated mortar specimens as well as chloride diffusion behavior. The mechanical properties such as compressive strength and flexural strength of recycled fine aggregate mortar (RFAM) were gradually decreased as RFA replacement ratio increase. The pore structure of RFAM was examined by permeability tests. The RFAM showed a increment in the permeability according to replacement ratio increase of RFA. But the chloride diffusion coefficient of RFAM was almost same up to 50% replacement ratio of RFA due to a chloride binding phenomenon of RFAM which may compensate the higher permeability of RFAM.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.3
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• pp.21-29
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• 1988

Evaluation of accurate design moments in two directions is a primary concern in designing R/C Slab. For this purpose, the use of finite element method utilizing isoparametric plate element is proposed. An example of the simply supported slab shows that the results agree well wth those from elastic plate theory throughout the span. The finite element solutions are also compared with those from equivalent frame method in a flat plate example. It is indicated that the distribution of total moment through the width of design strip using the ACI coefficients is unreasonable. In contrary to this, for the same strip model, the finite element method gives accurate moments in two directions. The proposed method can be applied to any geometric configuration of the slab system, thus the approach is considered to be much advantageous and improved one compared with existing methods.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.671-675
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• 2003

In accordance with the KRR-1 & 2 decommissioning project, the decontamination and dismantling activities of the KRR-2 auxiliary facilities, radioisotope production facilities, were completed from Aug 2001 to Dec 2002. The auxiliary facilities were composed of the concrete hot-cell, lead hot-cells and several laboratories for the radioisotope production. The dismantling objects are home hoods, experimental desks, sinks, and contaminated inner facilities. For the purpose of the safe decommissioning activity, the method statements and working procedures were set up. The manpower of the total 20,933 man-hour was required and several dismantling equipments were also. The maximum surface contamination is: 9.24 Bq/$\textrm{cm}^2$ in removable contamination and 350,000 cpm in fixed contamination. The total amount of 62.146 Ton was raised as dismantled waste with kinds of the concretes, wood, steels, etc. The collective dose was evaluated as 0.33 mam-mSv during this period.