• Journal of the Korean Chemical Society
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• v.44 no.1
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• pp.87-91
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• 2000

• Proceedings of the KIEE Conference
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• 1997.07f
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• pp.2055-2057
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• 1997

In this study, we present the DPS system which is consist of several converters in parallel and supply the power to the load. The characteristics of the DPS using AC-bus or DC-bus, and load current sharing technique are discussed. We apply these techniques to the high-power paralleled DC/DC converter, and present the design requirements considered in the system.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.116-120
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• 1989

The optimal control problem of linear Lumped Parameter Systems (LPS) and Distributed Parameter Systems (DPS) is studied by employing the technique of Walsh functions (WF). By the using the elegant operational properties of WF, a direct computational algorithm for evaluating the optimal control and trajectory of LPS and DPS is developed. Without the need of solving the traditional matrix Riccati equation, the WF approach in shown very simple in form and convenient for use of a computer. The approximation is in the sense of least squares employing WF as the basis and the results are in the piecewise constant and discrete form.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.3
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• pp.95-101
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• 1986

This paper describes two methods for analyzing distributed parameter systems (DPS) via Walsh series expansions. Firstly, a Walsh-Galerkin expansion approach technique (WGA) introduced by S.G. Tzafestas. is considered. The method which is based on Galerkin scheme, is well established by using Walsh series. But then, there are some difficulty in finding the proper basic functions at each systems. Secondly, a double Walsh series approach technique (DWA) is developed. The essential feature of DWA propoesed here is that it reduces the analysis problem of DPS to that of solving a set of linear algebraic equation which is extended in double Walsh series.

• Journal of computational fluids engineering
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• v.21 no.1
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• pp.72-77
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• 2016

In this study, effects of thurster axis tilting angle on the thruster-hull interaction and propulsion performance in a dynamic positioning system of offshore plant are numerically investigated. Straight and 7-degree tilted downward thruster models as a form of ducted propeller are considered. For numerical simulations, Reynolds averaged Navier-Stokes equations with SST turbulence model are solved by using STAR-CCM+. Results show that thruster-hull interaction is reduced in 7-degree tilted thruster model with lower vortex strength between thruster and hull bottom, although the propulsion performance does not have noticeable difference in a bollard condition.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.391-396
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• 2012

The Voltage Bus Conditioner(VBC) is a bidirectional DC-DC converter for damping the instability and any transients of the bus voltage in a DC Distributed Power System(DPS). In this paper, a PI controller for the VBC has been designed for the frequency domain. The proposed PI controller not only dampens the bus transients, but also keeps the storage voltage level. Simulation by Matlab/Simulink and experimental results are presented for the validity of the proposed control technique.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.28-30
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• 2014

Dynamic Positioning System(DPS)은 그 신뢰성 및 대체 시스템에 따라 IMO 및 각 선급에서 3개의 class(등급)로 나누고 있다. IMO MSC/Circ 645에 의하면 DPS는 Class 1, 2, 및 3로 나뉘어 있으며 등급이 높을수록 좀 더 신뢰성 있고 안전하게 DP 선박을 운용할 수 있다. 이러한 DPS의 등급은 DP 선박을 건조할 때 그 선박의 사용 목적 및 필요성 신뢰도에 따라 건조되고 있으나 최근에는 이미 건조되어 있는 DP 선박의 등급을 개조를 통해 변경하여 사용하기도 한다. 본 연구에서는 DP Class 1선박을 DP Class 2 선박으로 변경하기 위해서는 어떠한 IMO 및 선급 요건의 만족이 필요하며 이를 위해서 어떠한 설비의 추가가 필요한지를 알아보고 이를 실제 사례를 통해 확인 및 검증해 본다.

• Korean Journal of Computational Design and Engineering
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• v.8 no.2
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• pp.84-89
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• 2003

Axiomatic Design Theory is one of the most useful design methodologies which uses Functional Requirements(FRs) and Design Parameters(DPs) to make human designers more creative, to reduce the random search process, to minimize the iterative trial-and-error process, and to determine the best design among those proposed. In this research, we show how to develop a CAD system for an automotive rubber machinery using the axiomatic design approach to illustrate the effectiveness of the theory and we suggest a better way to select FRs and DPs in axiomatic design approach which can help designers to select them more effectively, objectively, and easily.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1289-1295
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• 2012

An active resonance damper for a DC Distributed Power System(DPS) with parallel loads is presented. Each pulse power load in a DC DPS comprises both a resistive power load and a step-up converter. The step-up converter behave as constant power load(CPL) when tightly regulated and usually cause a negative impedance instability problem. Furthermore, when an input filter is connected to a large constant power load, the instability of DC bus voltage. In this paper, a bidirectional DC/DC converter with a reduced storage capacitor quantitatively are proposed as a active resonance damper, to mitigate the voltage instability on the bus. The validity of the proposed method was confirmed by simulation and experimental works.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.97-98
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• 2006

High current behaviors of the grounded gate extended drain N-type metal-oxide-semiconductor field effects transistor (GG_EDNMOS) electro-static discharge (ESD) protection devices are analyzed. Simulation based contour analyses reveal that combination of BJT operation and deep electron channeling induced by high electron injection gives rise to the 2-nd on-state. Thus, the deep electron channel formation needs to be prevented in order to realize stable and robust ESD protection performance. Based on our analyses, general methodology to avoid the double snapback and to realize stable ESD protection is to be discussed.