• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1947-1955
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• 2013

The purpose of this paper is to present an photoelasticity technique for measuring the displacement and stress distribution in particle assembly subjected to shallow foundation loading. Photoelastic measurement technique was employed to visualize the force transmission of a particle assembly. A model assembly bounded by a steel frame was built by stacking bi-dimensional circular particles made of polycarbonate elastomer. Each particle was coated by a thin photoelastic sheet so that the force transmission represented by bright light stripes can be visualized. In a contacted particle, both magnitude and orientation of principal stress difference can also be measured via the photoelasticity technique. The different distributions of the contact stresses at the initial loading and near the failure were quantitatively compared. The photoelastic patterns and displacement fields observed in the pre-failure state disappears immediately after the buckling of confined force chains.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.55-60
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• 2010

The honeycomb composite joint structure designed for application to a tilting KTX railroad car body is subjected to bending loads of a cantilever type. Honeycomb sandwich composite panel-joint attached in the real tilting car body was fabricated and sectioned as several beam-joint specimens for the bending test. The fracture behaviors of these specimens under static loads were different from those under cyclic loads. Static bending loads caused shear deformation and fracture in the honeycomb core region, while fatigue cyclic bend loading caused delamination along the interface between the composite skin and the honeycomb core, and/or caused a fracture in the welded part jointed with the steel under-frame. These fracture behaviors could occur in other industrial honeycomb composite joints with similar sub-structures, and be used for improving design parameters of a honeycomb composite joint structure.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.620-627
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• 2014

In the contemporary age, social environment has changed from analog to digital. As a media is developed, the public is more familiar to digital than analog. In this society, media art rises as new art. One of the most useful methods in the media art is projection mapping. In this paper, I propose a realization process of artwork 'Cloned Me' that is realized by projection mapping method. Artwork is formed by projecting image contents that are visualized a music on a steel structure. It is different from media facade that the object projected contents has a story composition. It is a strength that the object and contents are connected by story and composition. Also it can be modified each other easily for harmony because the structure is assembly-type. A face that is projected by beam projection is consist of unique structure not fixed rectangular frame. Artwork 'Cloned Me' has significance that it reflects the present age to develop digital cloning.

• 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.

• Structural Engineering and Mechanics
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• v.54 no.1
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• pp.105-119
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• 2015

Structural damage detection using modal strain energy (MSE) is one of the most efficient and reliable structural health monitoring techniques. However, some of the existing MSE methods have been validated for special types of structures such as beams or steel truss bridges which demands improving the available methods. The purpose of this study is to improve an efficient modal strain energy method to detect and quantify the damage in complex structures at early stage of formation. In this paper, a modal strain energy method was mathematically developed and then numerically applied to a fixed-end beam and a three-story frame including single and multiple damage scenarios in absence and presence of up to five per cent noise. For each damage scenario, all mode shapes and natural frequencies of intact structures and the first five mode shapes of assumed damaged structures were obtained using STRAND7. The derived mode shapes of each intact and damaged structure at any damage scenario were then separately used in the improved formulation using MATLAB to detect the location and quantify the severity of damage as compared to those obtained from previous method. It was found that the improved method is more accurate, efficient and convergent than its predecessors. The outcomes of this study can be safely and inexpensively used for structural health monitoring to minimize the loss of lives and property by identifying the unforeseen structural damages.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.2
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• pp.52-62
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• 2015

This study aims at developing a new seismic resistant method by using precast concrete wall panels for existing low-rise, reinforced concrete beam-column buildings such as school buildings. Three quasi-static hysteresis loading tests were performed on one unreinforced beam-column specimen and two reinforced specimens with U-type precast wall panels. Top shear connection of the PC panel was required to show the composite strength of RC column and PC wall panel. However, the strength of the connection did not influence directly on the ultimate loading capacities of the specimens in the positive loading because the loaded RC column push the side of PC wall panel and it moved horizontally before the shear connector receive the concentrated shear force in the positive loading process. Under the positive loading sequence(push loading), the reinforced concrete column and PC panel showed flexural strength which is larger than 97% of the composite section because of the rigid binding at the top of precast panel. Similar load-deformation relationship and ultimated horizontal load capacities were shown in the test of PR1-LA and PR1-LP specimens because they have same section dimension and detail at the flexural critical section. An average of 4.7 times increase in the positive maximum loading(average 967kN) and 2.7 times increase in the negative maximum loading(average 592.5kN) had resulted from the test of seismic resistant specimens with anchored and welded steel plate connections than that of unreinforced beam-column specimen. The maximum drift ratios were also shown between 1.0% and 1.4%.

• 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.6
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• pp.1049-1058
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• 2009

Korea's Rolling stock workshop were established with the introduction of a railway, and became the center of industrial construction in the modern age of Korea. There still exist a lot of Rolling stock workshop buildings in the Youngsan Rolling stock workshop, the representative case of Korean Rolling stock workshop, and especially the study aims to look into modern architectural properties centered on those well-preserved buildings. Korea's Rolling stock workshop were built considering the proper conditions of location such as the neighboring districts from the port to transport vehicles and materials, the place where railroad lines are centralized, the short returning distance of railroad cars for entry and departure, and had the facility layout according to the order of a working process of vehicles, and the unique structure and the section facade shape with proper functions and sizes according to each purpose. In particular, they actively adopted steel-frame structure and reinforced concrete structure, and came to have the initial characteristics of Korea's modern industrial building which is called the structural transition. Therefore, this study aims to highlight the importance of Rolling stock workshop including the Youngsan Rolling stock workshop as industrial architecture heritage in the modern age of Korea.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.6
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• pp.35-45
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• 2008

To investigate the effects of residual displacement, the structural responses of buckling-restrained braced frames (BRBF) and special moment-resisting frames (SMRF) were evaluated for design-based excitations following an application of initial residual drift. The initial residual drift was applied to the structure in two ways. The first way was to simply apply the same earthquake record to the structure twice, with an appropriate pause between applications to allow the structural response from the first record to return to zero. The second way to apply the initial residual drift was to apply a pushover to the structure until it arrives at the desired residual drift value. According to the analysis results, the initial residual drifts had a significant effect on the responses of steel BRBF and SMRF. The responses of BRBF were more highly dependent on the initial residual deformation than the responses of SMRF. Therefore, in order to minimize the post-event repair cost, a reduction of residual drift is required.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.75-84
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• 2010

An in-cabinet response spectrum should be generated to perform the seismic qualification of devices and instruments mounted inside safety-related electrical equipment installed in nuclear power plants. The response spectrum is available by obtaining accurate seismic responses at the device mounting location of the cabinet. The dynamic behavior of most of electrical equipment may not be easily analyzed due to their complex mass and stiffness distributions. Considering these facts, this study proposes a procedure to estimate the seismic responses of a structure by a combination of a test and subsequent analysis. This technique firstly constructs the modal equations of the structure by using the experiment modal parameters obtained from the impact test. Then the seismic responses of the structure may be calculated by a mode superposition method. A simple steel frame structure was fabricated as a specimen for the validation of the proposed method. The seismic responses of the specimen were estimated by using the proposed technique and compared with the measurements obtained from the shaking table tests. The study results show that it is possible to accurately estimate the seismic response of the structure by using the experimental modal parameters obtained from the impact test.