• Structural Engineering and Mechanics
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• 제91권4호
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• pp.369-382
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• 2024

The earthquake loss assessment framework of ductile reinforced concrete (or RC) frame using component-performance -based methodology was studied in this paper. The elasto-plastic rotation angle was used as the damage indicator of structural component, and the damage-to-loss model was proposed on the basis of the deformation indicator of structural component. Dynamic instability during incremental dynamic analysis was taken as collapse criterion, and column failure was taken as criterion that structure has to be demolished. Expected earthquake losses of low-rise, mid-rise and high-rise RC frames were discussed. The expected earthquake loss encompassed collapse loss, demolition loss and repair loss. Furthermore, component groups of RC frame were divided into structural components, nonstructural components and rugged components. The results indicate that ductile RC frame is more likely to be demolished than collapse, especially in low-rise and mid-rise RC frames. Furthermore, the less collapse margin ratio the structure has, the more demolition probability the structure will suffer under rare earthquake. The demolition share of total earthquake loss might be more prominent than repair share and collapse share in ductile RC frame.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.1209-1210
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• 2008

Nowadays, electricity has become indispensable in our daily lives. Despite a lot of benefits of electricty, however, the electricty related injuries and damage have steadily increased. Arc is one of the main causes of electric fire of system. therefore, in this paper, a study of general properties in low voltage system that nonlinear system and linear system. also, we discussed arc properties for the system design normally operated without any hazard.

• 한국정밀공학회지
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• 제27권5호
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• pp.63-68
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• 2010

The use of aluminum alloy parts in the automotive industry has been increasing recently due to its low weight compared with steel to improve fuel efficiency. Companies in the auto parts' manufacturing sector are expected to meet the government's strict environmental regulations. In this study, manufacturing process of aluminum alloy bolt has been designed from forming to heat treatment. Bolt forming process is composed of cold forging for body and rolling for thread. In this study only cold forging process is considered by employing the finite element method. In the cold forging process, preform shape was designed and damage value was considered for die design. Two steps of forging process has been developed by the simulation and a prototype was manugactured accordingly. As a final process, solution heat treatment and aging process was employed. A final prototype was found to meet the required specifications of tensile strength and dimension.

• 한국조명전기설비학회지:조명전기설비
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• 제8권1호
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• pp.29-36
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• 1994

전시조명 설계에 있어서는 광방사 에너지의 흡수에 의해 기인하는 광화학 손상이나 온도상승 등의 작용효과를 고려해야 한다. 본 연구에서는 조명에 의한 손상에 매우 민감한 물질은 50[lx](연간적산조도: 120,000lx.h), 어느종도 민감한 물질을 200[lx](연간적산조도: 480,000lx.h)가 보존 및 관람객의 자연스러운 관람분위기를 줄 수 있는 조도기준이고, 광원은 상대손상계수가 작고 방사조도가 낮은 것을 사용하여 조영되도록 하는 기준을 설정하였다. 또한 전시실의 전반조명은 연색성이 높고 색온도가 낮은 광원으로 눈부심등에 의한 시각상의 손상이 없도록 조명하는 것이 좋은 조명이라는 결론을 얻었다.

• 한국산학기술학회논문지
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• 제13권9호
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• pp.3882-3888
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• 2012

일반 간선열차에서 주로 사용하는 저상승강장과 수도권 전동차에서 주로 사용하는 고상승강장을 동시에 안전운행하기 위한 니즈기술로서, 저상/고상 승강장에 상관없이 승하차할 수 있는 철도차량 승강문 스텝장치가 필요하다. 본 연구에서는 이를 대비하여 저상/고상 승강장 겸용 승강문 스탭의 기능 및 제작 요구사항을 검토하였다. 세밀히 검토한 결과, 합리적 설계안은 자체 언더프레임의 손상 및 철도승강장의 이격거리 변동성을 최소화 할 수 있는 텔레스코픽 슬라이딩 스텝방식이라고 판단된다. 또한 다양한 요구조건을 고려하여 각 단계별 스텝 동작 과정 및 제어 흐름도를 제시하였다.

• 복합신소재구조학회 논문집
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• 제5권1호
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• pp.28-36
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• 2014

This study describes the development of innovative connections between steel beams and concrete-filled tube columns that utilize a combination of low-carbon steel and super-elastic shape memory alloy components. The intent is to combine the recentering behavior provided by the shape memory alloys to reduce building damage and residual drift after a major earthquake with the excellent energy dissipation of the low-carbon steel. The analysis and design of structures requires that simple yet accurate models for the connection behavior be developed. The development of a simplified 2D spring connection model for cyclic loads from advanced 3D FE monotonic studies is described. The implementation of those models into non-linear frame analyses indicates hat the recentering systems will provide substantial benefits for smaller earthquakes and superior performance to all-welded moment frames for large earthquakes.

• Earthquakes and Structures
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• 제8권6호
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• pp.1277-1297
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• 2015

Post-tensioned precast segmental bridge columns have shown high level of strength and ductility, and low residual displacement, which makes them suffer minor damage after earthquake loading; however, there is still lack of confidence on their lateral response against severe seismic loading due in part to their low energy dissipation capacity. This study investigates the influence of major design factors such as post-tensioning force level, strands position, columns aspect ratio, steel jacket and mild steel ratio on seismic performance of self-centring segmental bridge columns in terms of lateral strength, residual displacement and lateral peak displacement. Seismic analyses show that increasing the continuous mild steel ratio improves the lateral peak displacement of the self-centring columns at different levels of post-tensioning (PT) forces. Such an increase in steel ratio reduces the residual drift in segmental columns with higher aspect ratio more considerably. Suggestions are proposed for the design of self-centring segmental columns with various aspect ratios at different target drifts.

• 한국지진공학회논문집
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• 제24권6호
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• pp.293-303
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• 2020

Seismic fragility was assessed for non-seismic reinforced concrete shear walls in Korean high-rise apartment buildings in order to implement an earthquake damage prediction system. Seismic hazard was defined with an earthquake scenario, in which ground motion intensity was varied with respect to prescribed seismic center distances given an earthquake magnitude. Ground motion response spectra were computed using Korean ground motion attenuation equations to match accelerograms. Seismic fragility functions were developed using nonlinear static and dynamic analysis for comparison. Differences in seismic fragility between damage state criteria including inter-story drifts and the performance of individual structural members were investigated. The analyzed building had an exceptionally long period for the fundamental mode in the longitudinal direction and corresponding contribution of higher modes because of a prominently insufficient wall quantity in such direction. The results showed that nonlinear static analyses based on a single mode tend to underestimate structural damage. Moreover, detailed assessments of structural members are recommended for seismic fragility assessment of a relatively low performance level such as collapse prevention. On the other hand, inter-story drift is a more appropriate criterion for a relatively high performance level such as immediate occupancy.

• Steel and Composite Structures
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• 제46권5호
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• pp.621-635
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• 2023

The combination of replaceable and repairable properties in structures has introduced new approach called "Low Damage Design Structures". These structural systems are designed in such a way that through self-centering, primary members and specific connections neither suffer damage nor experience permanent deformations after being exposed to severe earthquakes. The purpose of this study is the seismic assessment of steel moment resisting frames with the aid of rigid rocking cores. To this end, three steel moment resisting frames of 4-, 8-, and 12-story buildings with and without rocking cores were developed. The nonlinear static analysis and incremental dynamic analysis were performed by considering the effects of the vertical and horizontal components of 16 strong ground motions, including far-fault and near-fault arrays. The results reveal that rocking systems benefit from better seismic performance and energy dissipation compared to moment resisting frames and thus structures experience a lower level of damage under higher intensity measures. The analyses show that the interstory drift in structures equipped with stiff rocking cores is more uniform in static and dynamic analyses. A uniform interstory drift distribution leads to a uniform distribution of the bending moment and a reduction in the structure's total weight and future maintenance costs.

• 한국안전학회지
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• 제33권4호
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• pp.119-126
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• 2018

In recent years, as flood damage caused by heavy rains increased, the great-depth tunnel using urban underground space is emerging as a countermeasure of urban inundation. The great-depth tunnel is used to reduce urban inundation by using the underground space. The drainage efficiency of great-depth tunnel depends on the intake design, which leads to increase discharge into the underground space. The spiral intake and the tangential intake are commonly used for the inlet facility. The spiral intake creates a vortex flow along the drop shaft and reduces an energy of the flow by the wall friction. In the tangential intake, flow simply falls down into the drop shaft, and the design is simple to construct compared to the spiral intake. In the case of the spiral intake, the water level at the drop shaft entrance is risen due to the chocking induced by the flowrate increase. The drainage efficiency of the tangential intake decreases because the flow is not sufficiently accelerated under low flow conditions. Therefore, to compensate disadvantages of the previously suggested intake design, the multi-stage intake was developed which can stably withdraw water even under a low flow rate below the design flow rate. The hydraulic characteristics in the multi-stage intake were analyzed by changing the flow rate to compare the drainage performance according to the intake design. From the measurements, the drainage efficiency was improved in both the low and high flow rate conditions when the multi-stage inlet was employed.