• 한국해안·해양공학회논문집
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• 제24권2호
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• pp.138-148
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• 2012

경사제에 불규칙하게 작용하는 임의 크기의 다중하중으로 인해 피복재의 안정성에 대한 성능이 시간에 따라 어떻게 달라지는지를 해석할 수 있는 추계학적 신뢰성 해석 모형이 개발되었다. Hudson의 공식과 Melby 공식을 이용하여 재현기간에 따른 파고의 함수로 경사제 피복재의 초기 저항력 크기와 피해율을 확률적으로 산정할 수 있는 새로운 방법이 제시되었다. 생애기간에 대한 신뢰성 분석을 실시하여 시간에 따른 다중하중의 작용과 사용한계나 극한한계 등 한계상태에 따른 구조물의 성능을 올바로 해석할 수 있었다. 마지막으로 보수보강 목표확률을 시간에 따른 누적파괴확률의 결과와 조합하여 구조물 유지관리에서 가장 중요한 변수인 보수보강 시점을 정량적으로 산정할 수 있는 방법이 제시되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1234-1235
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• 2011

A DC Power Distribution Systems(DC PDS) are widely used in telecommunication system, electric vehicle, aircraft, military system, etc. In the DC PDS, DC bus voltage instability may be occurred by the operation of multiple loads such as pulsed power load, motor drive system, and constant power loads. To damp the transients of the DC bus voltage, the Voltage Bus Conditioner(VBC) with the PI compensator is used. In this paper, the validity of the proposed VBC system is verified by PSIM simulation package.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.538-540
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• 1997

A new dual half bridge induction heating cooker circuit with multiple loads is proposed for reducing the acoustics noise which is caused by the difference between operating frequencies q adjacent loads. This circuit has minimum loss due to the zero voltage switching characteristic. According to the mode analysis of the proposed circuit, we explain the operation of the dual half bridge induction heating cooker circuit The proto-type circuit with 2.8kW power consumption is builted and tested to verify the operation q the proposed circuit.

• 전산구조공학
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• 제2권2호
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• pp.73-83
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• 1989

2차원적인 유한요소들을 각 절점에서 6개의 자요도를 갖는 3차원인 입체로 결합함으로써, 횡하중을 받고 있는 합성 쉘 구조를 해석할 수 있는 프로그램 [MSSLL]을 개발하였다. 전체 구조물이 여러개의 반복되는 Substructure들로 이루어졌을 때에는, 인력의 소모를 극소화하고 계산시간을 절약할 수 있도록 해석과정에 Substructuring 기법을 본 프로그램에 도입하였다. 프로그램의 신뢰도를 확인하기 위하여 본 프로그램에 의한 해석결과와 다른 방법에 의한 결과를 비교분석 하였으며, 지진력을 받고 있는 8개의 개별 원추들로 구성된 쉘 구조의 거동에 대한 높이-경간비의 영향을 규명하기 위하여 변수연구를 수행하였다.

• Wind and Structures
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• 제29권2호
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• pp.129-137
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• 2019

The maximum along-wind displacement of a considerable amount of building under simulated wind loads is computed with the aim to produce a simple prediction model using multiple regression analysis with variables transformation. The Shinozuka and Newmark methods are used to simulate the turbulent wind and to calculate the dynamic response, respectively. In order to evaluate the prediction performance of the regression model with longer degree of determination, two complex structural models were analyzed dynamically. In addition, the prediction model proposed is used to estimate and compare the maximum response of two test buildings studied with wind loads by other authors. Finally, it was proved that the prediction model is reliable to estimate the maximum displacements of structures subjected to the wind loads.

• The Journal of the Acoustical Society of Korea
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• 제24권1E호
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• pp.34-37
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• 2005

Ryu et al. proposed a multiple target angle-tracking algorithm without a data association problem using angular innovations. This algorithm, however, needs the computational loads in proportion to the square number of sensors regardless of the number of targets, because it uses a nonlinear equation between the signal subspace and angular innovation. In this Paper, we proposed an efficient algorithm for the multiple target angle-tracking using angular innovations. The proposed algorithm extracts the angular innovations from noise subspace. Also, it is demonstrated by computer simulations dealing with the tracking of crossing targets. The simulation results show that the computational loads of the proposed algorithm are $80\%$ and $60\%$ of those of Ryu's algorithm for 3 targets and 6 targets without degrading the performance of the target tracking.

• Journal of Power Electronics
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• 제18권5호
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• pp.1479-1488
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• 2018

Power packet (PP) distribution system distributes power to different loads that share the same distribution cable in a packetized form. When compared with conventional power systems, a PP distribution system (PPDS) can reduce standby power, eliminate Point-of-Load (PoL) power conversion, and intelligently control the load demand from the source side. Due to the absence of PoL conversion, when multiple power sources at different voltage levels and conditioning requirements jointly send power to various loads at different voltage ratings, the generated voltage has an irregular shape. A large filter at each of the load sides is required to reduce such a large voltage ripple. In this paper, a single-inductor, multiple-input-single-output converter structure based multiple-energy-source mixer is proposed. It combines PP generation, maximum power point tracking (MPPT) of renewable energy sources (RESs) and filtering at the source side. To demonstrate the possible renewable energy integration, a PV panel is used as a power source together with other constant voltage sources. The PV power is approximately tracked using the constant voltage method and it is used for each of the PP generations. The proposed PP distribution system is experimentally verified and it is shown that a conventional PI controller is sufficient for stable system operation.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 가을 학술발표회 논문집
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• pp.229-236
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• 2004

A new three-node triangular shell element based on higher order zig-zag theory is developed for laminated composite shells with multiple delaminations. The present higher order zig-zag shell theory is described in a general curvilinear coordinate system and in general tensor notation. All the complicated curvatures of surface including twisting curvatures can be described in an exact manner in the present shell element because this element is based on geometrically exact surface representation. The displacement field of the proposed finite element includes slope of deflection. which requires continuity between element interfaces. Thus the nonconforming shape function of Specht's three-node triangular plate bending element is employed to interpolate out-of-plane displacement. The present element passes the bending and twisting patch tests in flat surface configurations. The developed element is evaluated through the buckling problems of composite cylindrical shells with multiple delaminations. Through the numerical examples it is demonstrated that the proposed shell element is efficient because it has minimal degrees of freedom per node. The accuracy of the present element is demonstrated in the prediction of buckling loads and buckling modes of shells with multiple delaminations. The present shell element should serve as a powerful tool in the prediction of buckling loads and modes of multi-layered thick laminated shell structures with arbitrary-shaped multiple delaminations.

• Structural Engineering and Mechanics
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• 제86권4호
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• pp.535-546
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• 2023

In the present paper, multiple interface cracks between a functionally graded orthotropic coating and an orthotropic half-plane substrate under concentrated loading are considered by means of the distribution dislocation technique (DDT). With the use of integration of Fourier transform the problem is reduced to a system of Cauchy-type singular integral equations which are solved numerically to compute the dislocation density on the surfaces of the cracks. The distribution dislocation is a powerful method to calculate accurate solutions to plane crack problems, especially this method is very good to find SIFs for multiple unequal cracks located at the interface. Hence this technique allows considering any number of interface cracks. The primary objective of this paper is to investigate the effects of the interaction of multiple interface cracks, load location, material orthotropy, nonhomogeneity parameters and geometry parameters on the modes I and II SIFs. Numerical results show that modes I/II SIFs decrease with increasing the nonhomogeneity parameter and the highest magnitude of SIF occurs where distances between the load location and crack tips are minimal.

• 대한기계학회논문집A
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• 제27권2호
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• pp.268-275
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• 2003

Generally, structural optimization is carried out based on external static loads. All forces have dynamic characteristics in the real world. Mathematical optimization with dynamic loads is extremely difficult in a large-scale problem due to the behaviors in the time domain. The dynamic loads are often transformed into static loads by dynamic factors, design codes, and etc. Therefore, the optimization results can give inaccurate solutions. Recently, a systematic transformation has been proposed as an engineering algorithm. Equivalent static loads are made to generate the same displacement field as the one from dynamic loads at each time step of dynamic analysis. Thus, many load cases are used as the multiple leading conditions which are not costly to include in modern structural optimization. In this research, it is mathematically proved that the solution of the algorithm satisfies the Karush-Kuhn-Tucker necessary condition. At first, the solution of the new algorithm is mathematically obtained. Using the termination criteria, it is proved that the solution satisfies the Karush-Kuhn-Tucker necessary condition of the original dynamic response optimization problem. The application of the algorithm is discussed.