• 한국구조물진단유지관리공학회 논문집
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• 제13권6호통권58호
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• pp.183-191
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• 2009

본 연구에서는 지진시 nailed-soil 굴착벽체의 안전율과 거동특성에 대하여 제시하였다. 시간이력해석을 이용하여 정적하중과 지진하중을 받는 nailed-soil 굴착벽체 전면부의 수평변위, 축력, 전단력, 모멘트를 해석하였다. Dawson과 Roth가 제안한 전단강도 감소기법에 바탕을 둔 안전율을 지진시 nailed-soil 굴착벽체의 안전율 계산에 사용하였다. 제안된 방법에 의한 안전율을 기존의 연구에서 산정된 안전율과 비교하여 그 타당성을 확인하였다.

• 수산해양기술연구
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• 제50권2호
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• pp.176-184
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• 2014

Nowadays, consumption of fisheries products is increasing. There are several factors, one of which is a quantitative development through aquaculture. Another factor is an increase qualitative consumption of fish which require that fish be supplied alive. This requires a lot of technical effort to transport the live fish that have low survival rate (c.f. tuna and mackerel) in coastal waters and in the open sea. To develop a towing cage for transporting the live fish, model test in a circulate water channel and simulation by computer tool were carried out. In order to spread vertically, floats were attached at the upper part of the cage, and iron chains attached at the lower part of the cage. For horizontal spreading, kites were attached on the cage. The tension and spreading performance of the cage were measured. The result shows that the tension and reduction ratio of inside volume of the cage were tended to increase with increased towing speeds. The suitable operation condition in towing cage was 1.0 m/s towing speeds with vertical spreading force 8.7 kN, horizontal spreading force 5.6 kN; in this case the reduction ratio of inside volume of the cage was estimated as 25%.

• Structural Engineering and Mechanics
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• 제13권4호
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• pp.369-385
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• 2002

Ductility capacity is comprehensively studied for steel moment-resisting frames. Local, story and global ductility are being considered. An appropriate measure of global ductility is suggested. A time domain nonlinear seismic response algorithm is used to evaluate several definitions of ductility. It is observed that for one-story structures, resembling a single degree of freedom (SDOF) system, all definitions of global ductility seem to give reasonable values. However, for complex structures it may give unreasonable values. It indicates that using SDOF systems to estimate the ductility capacity may be a very crude approximation. For multi degree of freedom (MDOF) systems some definitions may not be appropriate, even though they are used in the profession. Results also indicate that the structural global ductility of 4, commonly used for moment-resisting steel frames, cannot be justified based on this study. The ductility of MDOF structural systems and the corresponding equivalent SDOF systems is studied. The global ductility values are very different for the two representations. The ductility reduction factor $F_{\mu}$ is also estimated. For a given frame, the values of the $F_{\mu}$ parameter significantly vary from one earthquake to another, even though the maximum deformation in terms of the interstory displacement is roughly the same for all earthquakes. This is because the $F_{\mu}$ values depend on the amount of dissipated energy, which in turn depends on the plastic mechanism, formed in the frames as well as on the loading, unloading and reloading process at plastic hinges. Based on the results of this study, the Newmark and Hall procedure to relate the ductility reduction factor and the ductility parameter cannot be justified. The reason for this is that SDOF systems were used to model real frames in these studies. Higher mode effects were neglected and energy dissipation was not explicitly considered. In addition, it is not possible to observe the formation of a collapse mechanism in the equivalent SDOF systems. Therefore, the ductility parameter and the force reduction factor should be estimated by using the MDOF representation.

• 한국구조물진단유지관리공학회 논문집
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• 제10권4호
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• pp.145-154
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• 2006

본 논문은 외부 긴장재로 보강된 2경간 연속 강합성보의 내하력을 향상시키기 위한 방법을 제시하였다. 긴장재를 정모멘트 구간의 강주형 하부에 설치하였다. 이 방법은 정모멘트 뿐만 아니라 부모멘트도 감소시킬 수 있다. 강합성보를 긴장재로 보강함으로써 내하율 식에서 목표 내하율을 만족시키기 위한 긴장재 개수와 초기 긴장력의 결정방법을 기술하였다. 본 방법을 실교량의 강합성보에 적용하여 타당성을 입증하였다.

• 소성∙가공
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• 제20권8호
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• pp.548-554
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• 2011

A Finite Element (FE)-based model is proposed for predicting the roll force in an edger. The model is developed on the basis of the hypothetical mode of rolling and the least-squares regression analysis from the result of the FE approach. This model reflects the effect of process variables affected by the roll force, and has three dimensionless parameters, I.e., shape factor, reduction ratio and width-to-thickness ratio. The model prediction compared satisfactorily with experiment observations.

• Structural Engineering and Mechanics
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• 제34권1호
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• pp.1-14
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• 2010

The innovative intelligent fuzzy weighted input estimation method which efficiently and robustly estimates the unknown time-varying input force in on-line is presented in this paper. The algorithm includes the Kalman Filter (KF) and the recursive least square estimator (RLSE), which is weighted by the fuzzy weighting factor proposed based on the fuzzy logic inference system. To directly synthesize the Kalman filter with the estimator, this work presents an efficient robust forgetting zone, which is capable of providing a reasonable compromise between the tracking capability and the flexibility against noises. The capability of this inverse method are demonstrated in the input force estimation cases of the plate structure system. The proposed algorithm is further compared by alternating between the constant and adaptive weighting factors. The results show that this method has the properties of faster convergence in the initial response, better target tracking capability, and more effective noise and measurement bias reduction.

• Journal of Power Electronics
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• 제11권1호
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• pp.37-44
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• 2011

In this paper, a four-phase 8/6-pole 4-kW SR motor drive model is presented. Based on experimental data, the model allows an accurate simulation of a drive in dynamic operation. Simulations are performed and a laboratory type set-up is built based on a TI TMS320F2812 platform to experimentally verify the theoretical results obtained for a SR motor. To reduce acoustic noise and to correct the power factor of this drive, a two-stage power converter is proposed that uses a current source rectifier (CSR) as the input stage for the asymmetrical converter of the studied SRM. Employing the space-vector modulation (SVM) method in matrix converters, the CSR switching allows the dc link's capacitors to be eliminated and the power factor of the SRM drive to be improved. As the electrical motive force (emf) is directly proportional to the rotor speed, the input voltage to the machine can be programmed to be a function of the speed with the modulation index of the CSR, leading to a reduction in the acoustic noise of the SRM drive. Simulation of the whole SRM drive system is performed using MATLAB-Simulink. The results fully comply with the required conditions such as power factor correction with an improvement in the THD.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1997년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 1997
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• pp.201-208
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• 1997

In most seismic codes such as the Uniform Building Code(UBC), the response modification factor(or the force reduction factor)is used to reflect the capability of a structure in dissipating energy through inelastic behavior. The response modification factor is assigned according to structural system type. Ductile systems such as special moment-resisting steel frames are assigned larger values of the response modification factor, and are consequently designed for smaller seismic design forces. Therefore, structural damage may occur during a severe earthquake. To ensure safety of the structures, the suitability of the response modification factor used in aseismic design procedures shall be evaluated. The object of this study is to develop a method for the evaluating of the response modification factor. The validity of the evaluating method has been examined for several cases of different structures and different earthquake excitations.

• Structural Engineering and Mechanics
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• 제86권2호
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• pp.277-290
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• 2023

A supplementary reinforced concrete wall can be used to improve the seismic behavior of a buckling restrained braced frame as a mixed system. In such a novel system, the total lateral force is resisted by the combination of the RC wall system and the BRBF. There is not enough research on the response modification factor of such a mixed system. This paper investigates the response modification factor, and such relevant factors as ductility reduction factor and over strength factor for a system consisting of reinforced concrete wall and buckling restrained braced frame. To this purpose, nonlinear incremental dynamic analysis as well as static push over analysis are used for 6- to 14-story sample structures. The results show that for mixed considered systems, the mean value of response modification factor varies approximately from 7 to 9.

• Structural Engineering and Mechanics
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• 제62권4호
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• pp.443-453
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• 2017

The performance of bolted side-plated (BSP) beams is affected by the degree of transverse partial interaction, which is a result of the interfacial slip caused by transverse shear transfer between the bolted steel plates and the reinforced concrete beams. However, explicit formulae for the transverse shear transfer profile have yet to be derived. In this paper, a simplified piecewise linear shear transfer model was proposed based on force superposition principle and simplification of shear transfer profiles derived from a previous numerical study. The magnitude of shear transfer was determined by force equilibrium and displacement compatibility condition. A set of design formulae for BSP beams under several basic load cases was also derived. Then the model was verified by test results. A worked example was also provided to illustrate the application of the proposed design formulae. This paper sheds some light on the shear force transfer mechanism of anchor bolts in BSP beams, and offers a practical method to evaluate the influence of transverse partial interaction in strengthening design.