• Structural Engineering and Mechanics
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• 제58권2호
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• pp.259-276
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• 2016

Lead-rubber bearings (LRBs) have been used worldwide in seismic design of buildings and bridges owing to their stable mechanical properties and good isolation effect. We have investigated the effectiveness of LRBs in framed underground structures on controlling structural seismic responses. Nonlinear dynamic time history analyses were carried out on the well-documented Daikai Station, which collapsed during the 1995 Hyogoken-Nanbu earthquake. Influences of strength ratio (ratio of yield strength of LRBs to yield strength of central column) and shear modulus of rubber on structural seismic responses were studied. As a displacement-based passive energy dissipation device, LRBs reduce dynamic internal forces of framed underground structures and improve their seismic performance. An optimal range of strength ratios was proposed for the case presented. Within this range, LRBs can dissipate maximum input earthquake energy. The maximum shear and moment of the central column can achieve more than 50% reduction, whereas the maximum shear displacement of LRBs is acceptable.

• Steel and Composite Structures
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• 제18권6호
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• pp.1517-1539
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• 2015

Eccentrically braced frames (EBFs) often use conventional steel with medium yield strength. This system requires structural members with large cross-sections for well seismic behavior, which leads to increased material costs. In eccentrically braced frames with high strength steel combination (HSS-EBFs), links use Q345 steel (specified nominal yield strength 345 MPa), braces use Q345 steel or high strength steel while other structural members use high strength steel (e.g., steel Q460 with the nominal yield strength of 460 MPa or steel Q690 with the nominal yield strength of 690 MPa). For this approach can result in reduced steel consumption and increased economic efficiency. Several finite element models of both HSS-EBFs and EBFs are established in this paper. Nonlinear hysteretic analyses and nonlinear time history analyses are conducted to compare seismic performance and economy of HSS-EBFs versus EBFs. Results indicate that the seismic performance of HSS-EBFs is slightly poorer than that of EBFs under the same design conditions, and HSS-EBFs satisfy seismic design codes and reduce material costs.

• Earthquakes and Structures
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• 제15권3호
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• pp.319-334
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• 2018

In this paper, an analytical study was carried out to propose an optimum base-isolated system for the design of steel structures equipped with lead rubber bearings (LRB). For this, 5 and 10-storey steel moment resisting frames (MRFs) were designed as Special Moment Frame (SMF). These two-dimensional and three-bay frames equipped with a set of isolation systems within a predefined range that minimizes the response of the base-isolated frames subjected to a series of earthquakes. In the design of LRB, two main parameters, namely, isolation period (T) and the ratio of strength to weight (Q/W) supported by isolators were considered as 2.25, 2.5, 2.75 and 3 s, 0.05, 0.10 and 0.15, respectively. The Force-deformation behavior of the isolators was modelled by the bi-linear behavior which could reflect the nonlinear characteristics of the lead-plug bearings. The base-isolated frames were modelled using a finite element program and those performances were evaluated in the light of the nonlinear time history analyses by six natural accelerograms compatible with seismic hazard levels of 2% probability of exceedance in 50 years. The performance of the isolated frames was assessed in terms of roof displacement, relative displacement, interstorey drift, absolute acceleration, base shear and hysteretic curve.

• Earthquakes and Structures
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• 제18권2호
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• pp.233-248
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• 2020

In this article, one of the procedures to design viscous dampers proposed in literature is applied to 3D asymmetric-plan buildings, considering different distributions for the damping coefficients, which are assumed to be proportional to specific structural or response parameters. The main purpose was to investigate the effectiveness of different vertical and in-plan distributions of the damping coefficients of nonlinear viscous dampers for the seismic retrofit of existing buildings. For comparison purposes, all the distributions were applied utilizing both a simplified and an extended method for the 3D structures, where the simplified method takes into account only the translation in the seismic direction, and the extended method considers the translations along the two orthogonal directions together with the floor rotations. The proposed distributions were then applied to a typical case study involving an asymmetric-plan six-storey RC building. The effectiveness of the different distributions was examined through time-history analyses, assuming nonlinear behaviour for both the viscous dampers and the structural elements. The results of the nonlinear dynamic analyses were examined in terms of maximum and residual inter-storey drifts, peak floor accelerations and maximum damper forces.

• International Journal of Human Ecology
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• 제7권1호
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• pp.1-12
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• 2006

The numerous changes made during the Japanese colonial rule became the basis of the current housing in Korea. Therefore, in order to understand the modern Korean housing, it is essential to understand what the Korean traditional life styles admitted or changed, and how the foreign culture of that time influenced the Korean housing under the Japanese colonial rule. Content analysis through literature review was utilized for the study, and specific sources were research papers, books, magazines, newspapers, and novels. The period during the Japanese invasion was the most active era of modernization in the Korean history. For the housing culture, especially, it can be considered as the most significant period that accepted new housing cultures that replaced the old traditional housing. The Japanese and the Western styles of housing were introduced, new materials and collective production methods were used, and the symbol of the current urban housing in Korea, multi-family dwelling, was constructed. In conclusion, the Koreans did not directly use the Japanese and western housing culture, which were constructed during the Japanese colonial period. They were adapted and altered into Korean style, and eventually, produced various eclectic housing styles.

• 복식
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• 제59권9호
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• pp.131-145
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• 2009

Literature in beauty art is insufficient regarding beauty spot, though it has played an important role in beauty art history. This study aims at analyzing various patterns and decorative functions of beauty spots and examining their remarkable differences by place and time. It attempts to find the symbolistic characteristics of beauty patch which influenced European countries socially and culturally in the 17th and 18th centuries, findings are as follows: first, beauty spots are extremely various by patch patterns and by forms, e.g. Wha-Jeon(花鈿), Bindi and artificial points. In the view of cosmetic purpose, they have been used to beautify appearances, reveal social positions and express the desires like blessing or protection from evil. In the times of Baroque and Rococo, though temporarily, people with beauty spots and their belonged societies used them as communicative tools: obviously, they functioned symbolistically. This study surveyed 156 persons to find what cosmetic messages and images beauty spots present in the contemporary world. Using SPSS 13.0, the study analyzed the responses and found that beauty spots are still functioning and welcomed to let women look more beautiful and more attractive, though their cosmetic messages and sizes have been simplified and scaled down.

• Smart Structures and Systems
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• 제25권5호
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• pp.543-557
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• 2020

This paper presents a series of experimental and numerical investigations on a vertical isolation system with quasi-zero stiffness (QZS) property. The isolation system comprises a linear helical spring and disk spring. The disk spring is designed to provide variable stiffness to the system. Orthogonal static tests with different design parameters are conducted to verify the mathematical and mechanical models of the isolation system. The deviations between theoretical and test results influenced by the design parameters are summarized. Then, the dynamic tests for the systems with different under-load degrees are performed, including the fast sweeping tests, harmonic excitation tests, and half-sine impact tests. The displacement transmissibility, vibration reduction rate, and free vibration response are calculated. Based on the test results, the variation of the transmission rule is evaluated and the damping magnitudes and types are identified. In addition, the relevant numerical time history responses are calculated considering the nonlinear behavior of the system. The results indicate that the QZS isolation system has a satisfactory isolation effect, while a higher damping level can potentially promote the isolation performance in the low-frequency range. It is also proved that the numerical calculation method accurately predicts the transmission character of the isolation system.

• 한국소음진동공학회논문집
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• 제14권6호
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• pp.503-511
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• 2004

본 연구에서는 푸리에 모델, 확률 모델, 그리고 Newmark 설계 스펙트럼 방법과 같은 응답예측 모델을 사용하여 속도의존형 감쇠장치에 의해 제어되는 구조물의 응답과 제어기의 최대제어력을 예측하였다. 이를 위해, 유사 속도로부터 실제 속도를 예측하는 방법이 제안되었으며, 이 방법은 감쇠장치에 의해 증가되는 감쇠비의 실제속도에 대한 효과를 고려한다. 시간이력해석결과는 정확한 최대제어력을 예측하기 위해서는 실제속도가 사용되어야 하며, 제안된 방법에 의해 수정된 Newmark 설계 스펙트럼이 가장 전 주기구간에 걸쳐 정확한 예측 값을 산정함을 보여준다.

• 한국전자통신학회논문지
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• 제13권2호
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• pp.419-426
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• 2018

생태 관광이란 우수한 자연자원과 주변의 역사, 문화 자원 체험을 통해 느끼고 관찰하는 관광을 말하며, 현재 국민들의 여가생활 패턴이 변경됨에 따라 자연을 찾는 힐링(healing) 여행이 활성화 되고 있다. 본 논문에서는 계절에 따라 변화하고 특정한 시기에만 관람이 가능한 생태 관광 프로그램의 문제점을 해결하고 지속 가능한 생태 관광이 이루어 질 수 있는 관광 콘텐츠 시스템을 제안한다. 제안하는 관광 콘텐츠 시스템은 이미지 촬영 단말기에서 매일 촬영한 생태 관광 이미지 파일을 수거하여 동영상으로 변환 후 서버에 업로드 하면 관광객이 생태 관광 객체에 도착했을 때, 스마트폰을 이용하여 알려주고 식물의 성장 과정 등을 동영상으로 관람할 수 있도록 설계하였다.

• Journal of Welding and Joining
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• 제29권2호
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• pp.80-87
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• 2011

In this study, the friction stir spot welding (FSSW) of Mg alloy sheets has been tried using an apparatus devised with a CNC milling machine to give the precise control of joining condition including tool speed. The probe tool used is made of hard metal and composed of cylindrical shoulder and pin parts. The variation of morphologies formed after the friction stir spot welding depending on the plunge speed of the tool were investigated at each rpm of tool. The history of the temperature distribution and the vertical load induced during the spot welding with friction time were measured by using an Infrared Thermal Imager (THERMA CAMTM SC2000) and a loadcell located below the specimen fixture, respectively. Tensile-shear tests were also performed to evaluate the fracture load of welded specimens. In order to characterize the friction stir spot welding of Mg alloy sheets, the variation of the fracture load was discussed on micrographic observations, temperature distribution during the FSSW according to the plunge speeds of tool.