• 전자공학회논문지SC
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• 제39권6호
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• pp.27-33
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• 2002

본 논문에서는 종래의 한 프레임 내에서 매 서브필드마다 리셋구간에 램프파를 인가하던 구동 방식에서 한 프레임 내에 첫 번째 서브필드의 리셋구간에만 램프파를 인가하고, 나머지 서브필드에서는 유지방전을 실행한 셀 들만 초기화하여 고콘트라스트를 실현시킨 구동 파형에 대해 연구하였다. 실험결과 첫 번째 서브필드에서의 리셋구간에서만 램프파에 의해 광이 출력되고, 나머지 서브필드의 리셋구간에서는 광이 출력되지 않음을 확인하였다. 이것은 한 프레임 내에 10개의 서브필드를 사용할 때 종래의 구동 파형에 비해 어두운 화면에서 Background 휘도가 약 10배정도 낮음을 보여준다. 그리고 종래의 구동 파형에서 측정된 285:1의 콘트라스트 비율과 본 논문에서 사용한 구동 파형에 대해 측정한 3080:1의 콘트라스트 비율을 비교했을 때 약 10.8배정도 높아졌으며, 이로 인해 고콘트라스트를 실현시켰다.

• 한국농촌건축학회논문집
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• 제22권2호
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• pp.1-8
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• 2020

This study is intended to derive the adaptive reuse techniques through the history and aspects of new construction, extension, repair, and other works, limited to the deep and narrow lots facing Seongan-gil and Nammun-gil in Nammun-ro 2 ga of Cheongju, the historic urban area. The results are as follows. 1) In the case of newly built reinforced concrete buildings, the central part of the top floor of the residence or all floors are opened to the open space(void) to facilitate lighting and ventilation. This is developed as a convection phenomenon due to the temperature difference from the slits between buildings, which affects the entire air flow of the block. 2) The buildings of extension and repair are composed of two-story masonry or steel frame, both the front store facing the road and the house on the back, but it looks like one because it is in contact with each other. If only a small gap between the front and rear buildings is restored to an external space or a space equipped with sun light, a small breath can be provided in lighting and ventilation. 3) The existing two-story wooden stores and houses have lost their external space due to repairs. With minimal intervention to restore the small courtyard, slits, and space under the eaves, it will not only improve lighting and ventilation, but also create a unique appearance as a segment of the elongated store.

• Smart Structures and Systems
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• 제17권6호
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• pp.957-980
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• 2016

Structural damage detection (SDD) is a challenging task in the field of structural health monitoring (SHM). As an exploring attempt to the SDD problem, a hybrid self-adaptive Firefly-Nelder-Mead (SA-FNM) algorithm is proposed for the SDD problem in this study. First of all, the basic principle of firefly algorithm (FA) is introduced. The Nelder-Mead (NM) algorithm is incorporated into FA for improving the local searching ability. A new strategy for exchanging the information in the firefly group is introduced into the SA-FNM for reducing the computation cost. A random walk strategy for the best firefly and a self-adaptive control strategy of three key parameters, such as light absorption, randomization parameter and critical distance, are proposed for preferably balancing the exploitation and exploration ability of the SA-FNM. The computing performance of the SA-FNM is evaluated and compared with the basic FA by three benchmark functions. Secondly, the SDD problem is mathematically converted into a constrained optimization problem, which is then hopefully solved by the SA-FNM algorithm. A multi-step method is proposed for finding the minimum fitness with a big probability. In order to assess the accuracy and the feasibility of the proposed method, a two-storey rigid frame structure without considering the finite element model (FEM) error and a steel beam with considering the model error are taken examples for numerical simulations. Finally, a series of experimental studies on damage detection of a steel beam with four damage patterns are performed in laboratory. The illustrated results show that the proposed method can accurately identify the structural damage. Some valuable conclusions are made and related issues are discussed as well.

• Structural Engineering and Mechanics
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• 제39권1호
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• pp.125-145
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• 2011

Pushover analysis has gained significant popularity as an analytical tool for realistic determination of the inelastic behaviour of RC structures. Though significant work has been done to evaluate the demands realistically, the evaluation of capacity and realistic failure modes has taken a back seat. In order to throw light on the inelastic behaviour and capacity evaluation for the RC framed structures, a 3D Reinforced concrete frame structure was tested under monotonically increasing lateral pushover loads, in a parabolic pattern, till failure. The structure consisted of three storeys and had 2 bays along the two orthogonal directions. The structure was gradually pushed in small increments of load and the corresponding displacements were monitored continuously, leading to a pushover curve for the structure as a result of the test along with other relevant information such as strains on reinforcement bars at critical locations, failure modes etc. The major failure modes were observed as flexural failure of beams and columns, torsional failure of transverse beams and joint shear failure. The analysis of the structure was by considering all these failure modes. In order to have a comparison, the analysis was performed as three different cases. In one case, only the flexural hinges were modelled for critical locations in beams and columns; in second the torsional hinges for transverse beams were included in the analysis and in the third case, joint shear hinges were also included in the analysis. It is shown that modelling and capturing all the failure modes is practically possible and such an analysis can provide the realistic insight into the behaviour of the structure.

• 한국컴퓨터그래픽스학회논문지
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• 제3권2호
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• pp.1-13
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• 1997

가상 현실 시스템은 사실감과 몰입감을 동시에 제공해야 한다. 사실감은 사실적인 영상에 의해 생성되기 때문에 가상 환경의 각 물체는 특정에 따라 자세히 표현하고 빛에 의한 반사도 충분히 고려해야 한다. 몰입감은 사실적인 움직임과 빠른 반응 속도로 정의되므로 가상 환경은 가능한 빠르게 렌더링되고 사용자의 의도에 따라 움직임이 일어나야 한다. 유한 개의 상세도 레넬을 가지는 불체로 구성된 가상환경은 시점에 따라 물체의 석절한 상세도 레벨을 선택해야 한다. 본 논문에서는 상세도 레벨의 선택 문제를 에러(상세도 레벨 간의 영상에서의 차이), cost( 렌더링 시간), L -distance( 전번 프레임과의 레벨 차이)를 정의하여 형식화한다. 또한, 이러한 문제를 풀기 위하여 well-distributed adaptive algorithm을 제시 한다.

• 한국조경학회지
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• 제29권1호
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• pp.67-79
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• 2001

The purpose of this research is to evaluate the biotope value in a metropolitan area after constructing the biotope evaluation model to develop biotope networking in the light of ecological landscape planning. In addition this study is to provide a basic frame of constructing the biotope networking system in the future with the evaluation results. The scope of this research is limited to high density residential area including some part of the forest adjacent to urban boundary. The results of the classified biotope in the research area have been turned out to be 24 patterns. According to the result of estimated nature value having the forth grade, three were forests combined with urban natural parks, schools near forests, and grasslands. There is a little place having first grade. We an deduce this fact that we have surveyed biotopes, having the minimum nature value and wider than children's park. As for the result of evaluated the structure, there were the forests of Seong-Dong, Meaho-Dong, and Kumho river, which is the forth grade. As for the evaluation of connection-function, the followings area were evaluated as the third grade-linear biotopes having highly valued and sustainable similarity - Seoul-Pusan Railroad, Dong-Daegu St., Kumho river, river basins. Bum대 park and a botanic park near Suesung lake, As for the evaluated the buffer-function, higly valued production biotopes, existing at a transition belt between he residential density areas, are Sawol-Dong, Meaho-Dong and Kumho river. When each of the indexes was evaluated, the core of the biotop contained most of natural biotopes. Large artificial biotopes were evaluated as an important biotopes, while small artificial biotopes were classified as a dot biotope. The future research on the concrete biotope networking construction, based upon performed evaluation in this research, should be conducted.

• Earthquakes and Structures
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• 제18권6호
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• pp.677-689
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• 2020

A building structural system of moment resisting frame (MRF) with concrete filled steel tubular (CFST) columns and wide flange H beams, is one of the most conveniently constructed structural systems. However, there were few studies on evaluating seismic performance of full-scale CFST columns under high axial compression. In addition, some existing famous design codes propose various limits of width-to-thickness ratio (B/t) for steel tubes of the ductile CFST composite members. This study was intended to investigate the seismic behavior of CFST columns under high axial load compression. Four full-scale square CFST column specimens with a B/t of 42 were carried out that were subjected to horizontal cyclic-reversal loads combined with constantly light, medium and high axial loads and with a linearly varied axial load, respectively. Test results revealed that shear strength and deformation capacity of the columns significantly decreased when the axial compression exceeded 0.35 times the nominal compression strength of a CFST column, P₀. It was obvious that the higher the axial compression, the lower both the shear strength and deformation capacities were, and the earlier and faster the shear strength degradation occurred. It was found as well that higher axial compressions resulted in larger initial lateral stiffness and faster degradation of post-yield lateral stiffness. Meanwhile, the lower axial compressions led to better energy dissipation capacities with larger cumulative energy. Moreover, the study implied that under axial compressions greater than 0.35P₀, the CFST column specimens with B/t limits recommended by AISC 360 (2016), ACI 318 (2014), AIJ (2008) and EC4 (2004) codes do not provide ultimate interstory drift ratio of more than 3% radian, and only the limit in ACI 318 (2014) code satisfies this requirement when axial compression does not exceed 0.35P₀.

• Wind and Structures
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• 제28권3호
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• pp.181-190
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• 2019

Light-frame wood structures have the ability to carry gravity loads. However, their performance during severe wind storms has indicated weakness with respect to resisting uplift wind loads exerted on the roofs of residential houses. A common failure mode observed during almost all main hurricane events initiates at the roof-to-wall connections (RTWCs). The toe-nail connections typically used at these locations are weak with regard to resisting uplift loading. This issue has been investigated at the Insurance Research Lab for Better Homes, where full-scale testing was conducted of a house under appropriate simulated uplift wind loads. This paper describes the detailed and sophisticated numerical simulation performed for this full-scale test, following which the numerical predictions were compared with the experimental results. In the numerical model, the nonlinear behavior is concentrated at the RTWCs, which is simulated with the use of a multi-linear plastic element. The analysis was conducted on four sets of uplift loads applied during the physical testing: 30 m/sincreased by 5 m/sincrements to 45 m/s. At this level of uplift loading, the connections exhibited inelastic behavior. A comparison with the experimental results revealed the ability of the sophisticated numerical model to predict the nonlinear response of the roof under wind uplift loads that vary both in time and space. A further component of the study was an evaluation of the load sharing among the trusses under realistic, uniform, and code pressures. Both the numerical model and the tributary area method were used for the load-sharing calculations.

• Journal of the Korean Wood Science and Technology
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• 제47권5호
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• pp.547-556
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• 2019

Thinned, small larch logs have small diameters and no value-added final use, except as wood chips, pallets, or fuel wood, which are products with very low economic value; however, their mechanical strength is suitable for structural applications. In this study, small larch logs were sawed, dried, and cut into square timbers (with a $90mm{\times}90mm$ cross section) that were laterally glued to form core panels used to manufacture cross-laminated timber (CLT) wall panels. The surface and back of these core panels were covered with 12-mm-thick structural plywood panels, used as cross bands to obtain three-ply CLT wall panels. This attachment procedure was conducted in two different ways: gluing and pressing (CGCLT) or gluing and nailing (NGCLT). The size of the as-manufactured CLT panels was $1,220mm{\times}2,440mm$, the same as that of the plywood panels. The final wall panels were tested under lateral shear force in accordance with KS F 2154. As the lateral load resistance test required $2,440mm{\times}2,440mm$ specimens, two CLT wall panels had to be attached in parallel. In addition, the final CLT panels had tongued and grooved edges to allow parallel joints between adjacent pieces. For comparison, conventional light-frame timber shear walls and midply wall systems were also tested under the same conditions. Shear walls with edge nail spacing of 150 mm and 100 mm, the midply wall system, and the fabricated CGCLT and NGCLT wall panels exhibited maximum lateral resistances of 6.1 kN/m (100%), 9.7 kN/m (158%), 16.9 kN/m (274%), 29.6 kN/m (482%), and 35.8 kN/m (582%), respectively.

• 대한건축학회논문집:계획계
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• 제34권7호
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• pp.3-12
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• 2018

The present remodeling makes almost no difference from rebuilding as all the building materials are removed remaining frame structure only. And, in case of vertical extension of building, higher construction cost and safety problem occur. The Ministry of Land, Transport and Maritime Affairs, therefore, recommends customized remodeling that can be made in light of the resident' needs such as parking lot, elevator, bathroom, and room for the alternative of remodeling of vertical extension of building. The purpose of this study is to present real data that can be referred to the constructor's decision making before starting the remodeling, by investigating and analyzing the weight and importance between evaluation factors for customized remodeling at the completed time of remodeling. Accordingly, the factors were divided into environmental factor, social factor, and economical factor, and the survey was performed for the residents living in remodeling houses. In addition, for the professionals, AHP (Analytic Hierarchy Process) has been carried out for the priority in the customized remodeling. For environmental factor, the level of importance made difference from that before remodeling, except parking level. For social factor, every item, including psychological satisfaction and community satisfaction, made difference. For economical factor, the recognition level of importance in rent made difference, except sale price of the factor for price satisfaction. In case of the factor for cost satisfaction, it was checked that construction cost and administration cost both could be considered important. As a result of AHP, the most importantly emphasized item was construction cost, and sale price, administration cost, residence structure, and parking lot were followed by priority in order. This study could contribute to reliably settle down customized remodeling by giving reasonable and substantial help from the analysis of the differences in the customized remodeling items before/after the remodeling.