• Earthquakes and Structures
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• 제26권5호
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• pp.383-400
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• 2024

For a conventionally repaired frame-supported-transfer-slab (FSTS) reinforced concrete (RC) structure, both the transfer slab and the beam-to-column and transfer slab-to-column joints remain vulnerable to secondary earthquakes. Aimed at improving the seismic performance of a damaged FSTS RC structure, an innovative retrofitting scheme is proposed, which adopts the sector lead rubber dampers (SLRDs) at joints after the damaged FSTS RC structure is repaired by conventional approaches. In this paper, a series of quasi-static cyclic tests was conducted on a large-scale retrofitted FSTS RC structure. The seismic performance was evaluated and the key test results, including deformation characteristics, damage pattern, hysteretic behaviour, bearing capacity and strains on key components, were reported in detail. The test results indicated that the SLRDs started to dissipate energy under the service level earthquake, and thus prevented damages on the beam-to-column and transfer slab-to-column joints during the secondary earthquakes and shifted the plastic hinges away from the beam ends. The retrofitting scheme of using SLRDs also achieved the seismic design concept of 'strong joint, weak component'. The FSTS RC structure retrofitted by the SLRDs could recover more than 85% bearing capacity of its undamaged counterpart. The hysteresis curves were featured by the inverse "S" shape, indicating good bearing capacity and hysteresis performance. The deformation capacity of the damaged FSTS RC structure retrofitted by the SLRDs met the corresponding codified requirements for the case of the maximum considered earthquake, as set out in the Chinese seismic design code. The stability of the FSTS RC structure retrofitted by the SLRDs, which was revealed by the developed stains of the RC frame and transfer slab, was improved compared with the undamaged FSTS RC structure.

• Journal of Computational Design and Engineering
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• 제2권1호
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• pp.67-72
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• 2015

Recently, along with the improvements of geometry modeling methods using sketch-based interface, there have been a lot of developments in research about generating surface model from 3D curves. However, surfacing a 3D curve network remains an ambiguous problem due to the lack of geometric information. In this paper, we propose a new algorithm for estimating the normal vectors of the 3D curves which accord closely with user intent. Bending energy is defined by utilizing RMF(Rotation-Minimizing Frame) of 3D curve, and we estimated this minimal energy frame as the one that accords design intent. The proposed algorithm is demonstrated with surface model creation of various curve networks. The algorithm of estimating geometric information in 3D curves which is proposed in this paper can be utilized to extract new information in the sketch-based modeling process. Also, a new framework of 3D modeling can be expected through the fusion between curve network and surface creating algorithm.

• 전기학회논문지
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• 제64권9호
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• pp.1315-1322
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• 2015

This paper proposes an active islanding detection method for the BESS (Battery Energy Storage System) with 3-phase inverter which is connected to the AC grid. The proposed method adopts the DDSRF (Decoupled Double Synchronous Reference Frame) PLL (Phase Locked-Loop) so that the independent control of positive-sequence and negative-sequence current is successfully carried out using the detected phase angle information. The islanding state can be detected by sensing the variation of negative-sequence voltage at the PCC (Point of Common Connection) due to the injection of 2-3% negative-sequence current from the BESS. The proposed method provides a secure and rapid detection under the variation of negative-sequence voltage due to the sag and swell. The feasibility of proposed method was verified by computer simulations with PSCAD/EMTDC and experimental analyses with 5kW hardware prototype for the benchmark circuit of islanding detection suggested by IEEE 1547 and UL1741. The proposed method would be applicable for the secure detection of islanding state in the grid-tied Microgrid.

• 한국CDE학회논문집
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• 제10권1호
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• pp.40-48
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• 2005

A hydraulic hose is an important part of the hydraulic system which transmits power using pressurized fluids. It allows relative motion between components at each end of the hose assembly, and it is much easier to route a hose assembly than it is to bend and install a rigid tubing assembly. Unnecessary loads, which drop the hose's pressure capability and shorten service life, depend on a hose-routing. Therefore, the Hydraulic system designers must be aware to consider unnecessary load does not affect the here. For this consideration in an early stage of the design process, CAD system must support the hose assembly routing design function which is to generate routing path and design fitting angle properly. This paper proposes 2 methods. One is to generate curves that are similar to routing paths of the real hose assembly using the energy minimization method and the optimization method. The other is to design fitting angles that are important design elements of a hose assembly using the Parallel Transport Frame. To implement the proposed methods above, commercial CAD software, CATIA has been integrated with our program.

• International Journal of Automotive Technology
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• 제8권1호
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• pp.93-102
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• 2007

The frontal crash optimization of an engine room member using the response surface method was studied. The engine room member is composed of the front side member and the sub-frame. The thicknesses of the panels on the front side member and the sub-frame were selected as the design variables. The purpose of the optimization was to reduce the weight of the structure, under the constraint that the objective quantity of crash energy is absorbed. The response surface method was used to approximate the crash behavior in mathematical form for optimization procedure. To research the effect of the regression method, two different methodologies were used in constructing the response surface model, the least square method and the moving least square method. The optimum with the two methods was verified by the simulation result. The precision of the surrogate model affected the optimal design. The moving least square method showed better approximation than the least square method. In addition to the deterministic optimization, the reliability-based design optimization using the response surface method was executed to examine the effect of uncertainties in design variables. The requirement for reliability made the optimal structure be heavier than the result of the deterministic optimization. Compared with the deterministic optimum, the optimal design using the reliability-based design optimization showed higher crash energy absorption and little probability of failure in achieving the objective.

• 한국강구조학회 논문집
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• 제22권3호
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• pp.261-269
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• 2010

현재 보다 다양한 형태의 건축물 설계를 가능하게 하는 대표적인 구조 시스템으로 다이아그리드 시스템이 있다. 다이아그리드 시스템은 접합부 설계 및 시공의 어려움과 가새 부재 좌굴에 의해 내진성능이 저하된다는 단점이 있으며, 이를 보안하기 위해 비좌굴 가새를 이용한 다이아그리드 시스템을 제안하였다. 본 연구에서는 다이아그리드 시스템과 다이아그리드 BRB 시스템의 골조 실험을 통해 초기 강성, 연성 능력과 에너지 소산능력을 평가였다. 반복가력실험 결과 Diagrid BRB의 초기 강성과 연성능력이 더 크게 나타났으며, BRB 항복 이후에도 지속적인 에너지 흡수가 이루어짐을 확인할 수 있었다.

• Steel and Composite Structures
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• 제37권5호
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• pp.571-587
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• 2020

In this article the seismic demand and performance of two recent braced steel frames named steel moment frames with the elliptic bracing (ELBRFs) are assessed through a laboratory program and numerical analyses of FEM. Here, one of the specimens is without connecting bracket from the corner of the frame to the elliptic brace (ELBRF-E), while the other is with the connecting brackets (ELBRF-B). In both the elliptic braced moment resisting frames (ELBRFs), in addition to not having any opening space problem in the bracing systems when installed in the surrounding frames, they improve structure's behavior. The experimental test is run on ½ scale single-story single-bay ELBRF specimens under cyclic quasi-static loading and compared with X-bracing and SMRF systems in one story base model. This system is of appropriate stiffness and a high ductility, with an increased response modification factor. Moreover, its energy dissipation is high. In the ELBRF bracing systems, there exists a great interval between relative deformation at the yield point and maximum relative deformation after entering the plastic region. In other words, the distance from the first plastic hinge to the collapse of the structure is fairly large. The experimental outcomes here, are in good agreement with the theoretical predictions.

• Earthquakes and Structures
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• 제8권6호
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• pp.1453-1461
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• 2015

In this article the non-linear behavior of the shear wall with low yield stress retrofitted with Glass Fiber Reinforced Polymer (GFRP) is investigated under pushover loading. The models used in this study are in ${\frac{1}{2}}$ scale of one story frame and simple steel plates with low yield stress filled the frame span. The models used were simulated and analyzed using finite elements method based on experimental data. After verification of the experimental model, various parameters of the model including the number of GFRP layers, fibers positioning in one or two sides of the wall, GFRP angles in respect to the wall and thickness of the steel plate were studied. The results have shown that adding the GFRP layers, the ultimate shear capacity is increased and the amount of energy absorbed is decreased. Besides, the results showed that using these fibers in low-thickness plates is effective and if the positioning angle of the fibers on the wall is diagonal, its behavior will improve.

• 한국음향학회지
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• 제32권2호
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• pp.147-156
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• 2013

본 논문에서는 이동하는 로봇에 탑재한 대화체 음성인식기의 주위 잡음 환경에 강인한 새로운 음성 끝점 검출 기법을 제안한다. 기존의 기법은 특징 값의 갑작스러운 변화점을 찾기 위해 에지 검출 필터(edge detection filter)를 적용하여 끝점을 찾았다. 하지만 프레임 에너지의 특징은 잡음 환경에서 불안정하기 때문에 음성의 끝점을 정확하게 찾기 어렵다. 그러므로 두 번의 고속 퓨리에 변환과 통계적 모델 기반의 특징 추출 기법을 제안하여 에지 검출 필터에 적용한다. 제안한 기법이 기존의 기법보다 강인한 특징이 될 수 있음을 본 실험을 통하여 확인하였다.

• 한국통신학회논문지
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• 제32권5C호
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• pp.520-529
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• 2007

본 논문에서는 웨이블릿 변환 기반 스케일러블 비디오 부호화에서 가장 중요한 요소 기술인 움직임 보상 시간적 필터링 방법의 성능에 관련된 요소들의 특성을 파악하고, 기존의 DCT 기반의 하이브리드 부호화에서 사용된 움직임 예측 방법과 가변 크기 블록을 사용한 움직임 예측 방법을 적용한 향상된 MCTF (Motion Compensated Temporal Filtering) 방법을 제안한다. 이를 통하여 시간적 필터링 과정에서의 연결성을 높이고, 프레임간 에너지를 저/고주파 프레임으로 효율적으로 분해할 수 있다. 그 결과, 고주파 프레임의 에너지를 줄여, 엔트로피 부호화 비트율을 줄일 수 있다. 본 논문에서 제안하는 방법을 적용하여 모의 실험한 결과, 고주파 프레임에 포함된 에너지가 최대 25.86%까지 감소하는 것을 확인하였다.