• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.129-130
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• 2006

This paper presents a optimal power flow calculation algorithm considering voltage and transient stability. In this method, voltage stability margin and transient stability constraints is incorporated into a optimal power flow calculation formulation to guarantee adequate voltage and transient security levels in power system. In addition, this paper provides the Effect of Nodal Price and decomposed Element in Power System Operation. This Effect can be applied in the Estimation of Electric rates because the Electric market will be Competitive Market. The proposed method is applied to IEEE-24 Reliability Test System and the results shows the effectiveness of the method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.58-60
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• 2005

This paper presents a optimal power flow calculation algorithm considering voltage and transient stability. In this method, voltage stability margin and transient stability constraints is incorporated into a optimal power flow calculation formulation to guarantee adequate voltage and transient security levels in power system. The proposed method is applied to IEEE-24 Reliability Test System and the results shows the effectiveness of the method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.171-175
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• 1989

Newton-OPF proposed by W.F Tinny and his fellows in 1984 is most useful and powerful algorithm in optical power flow calculation. But, several problems prevent its application to practical uses. The problems are determination of active sets, initial values of variables, soft and hard weights, and discrete variables such as transformer taps. In this paper, convergence characteristics of Newton OPF is analyzed with effects of these factors using wide - used 5-bus sample system. Wide - use of results in this paper is appreciated.

• 대한전기학회논문지:전력기술부문A
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• 제50권6호
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• pp.259-264
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• 2001

The electric utility industry around the world is undergoing a revolutionary transition from vertically integrated monopoly structures to a competitive structures. Competition in an open transmission access(OTA) makes the market participants access easily the transmission system in a non-discriminatory and equitable manner. The competitions of suppliers and customers make the electric market price change every hour. This paper presents a web program in the internet environment with a function of optimal power flow(OPF) calculation. The Web program gives the nodal marginal cost and the congestion charge using the shadow prices resulted from OPF. This web program is realized by a Perl and JAVA languages, and using the common gateway interface(CGI).

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.113-119
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• 2001

Interaction of flow through an Impeller and a Vaned Diffuser in Centrifugal Compressor was investigated using the 3-dimensional Wavier-Stokes solution method. To consider the interaction effect of impeller and vaned diffuser, Inlet boundary conditions are imposed with the results of the steady calculation of the impeller and rotates with time. The results have been compared to steady computation results and experiment. From this, it is discussed about the compatability of the method and the advantage and disadvantage of the steady calculation.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.83-86
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• 2003

Complete prediction of second order permeability tensor for three dimensional preform such as plain woven fabric and braided preform is critical to understand the resin transfer molding process of composites. The permeability can be obtained by various methods such as analytic, numerical, and experimental methods. For several decades, the permeability has studied numerically to avoid practical difficulty of many experiments. However, the predicted permeabilities are a bit wrong compared with experimentally measured data. In this study, numerical calculation of permeability was conducted for two kinds of preforms i.e., plain woven fabric and circular braided preform. In order to consider intra-tow flow in the unit cell of preform the proposed flow coupled model was used for plain woven fabric and the Brinkman equation was solved in the case of the braided preform.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.369-372
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• 2002

Under the assumption of potential flow, free-surface flows around a 2-dimensional hydrofoil are calculated by high-order spoctral/boundary-integral method. This method is one of the most efficient numerical methods by which the nonlinear interactions between hydrofoil and free-surface can be simulated in time-domain. Comparisons of the calculated free-surface profiles with other experimental results show relatively good agreements. As another example, free-surface flow generated by the heaving and translating hydrofoil is calculated and discussed.

• 대한조선학회논문집
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• 제52권5호
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• pp.380-386
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• 2015

Panel methods are useful tools for analyzing fluid-flow around a wing section. It has the advantage of fast and accurate calculation, compared to other CFD Methods such as RANS solvers. This paper suggests a piecewise linear panel method in order to improve accuracy of existing panel methods by changing the piecewise constant singularity strength to linear singularity strength(for dipole strength). The piecewise linear panel method adopts the linear distribution of singularity strength, while control point is located at the node of each panel. Formulation of the piecewise linear panel method is given, and some calculation results are shown for typical wing sections.

• 수산해양기술연구
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• 제28권2호
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• pp.228-239
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• 1992

The purpose of the present research is to develop an efficient numerical method for the calculation of potential flow and predict the wave-making resistance for the application to ship design of tuna purse seiner. The paper deals with the numerical calculation of potential flow around the series 60 with forward velocity by the new slender ship theory. This new slender ship theory is based on the asymptotic expression of the Kelvin-source, distributed over the small matrix at each transverse section so as to satisfy the approximate hull boundary condition due to the assumption of slender body. Some numerical results for series 60, C sub(b) =0.6, hull are presented in this paper. The wave pattern and wave resistance are computed at two Froude numbers, 0.267 and 0.304. These results are better than those of Michell's thin ship theory in comparison with measured results. However, it costs much time to compute not only wave resistance but also wave pattern over some range of Froude numbers. More improvements are strongly desired in the numerical procedure.

• 소성∙가공
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• 제25권4호
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• pp.242-247
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• 2016

CFD simulation with FlowVision^® is used to evaluate the capability of cooling channel in hot press forming dies. Two different types of cooling channels, dry drilled and pocket types are considered for comparison. Two different approaches for simulating cooling channel are considered. One is single-phase velocity calculation for coolant only and the other is multiphase thermal and velocity calculation for die, blank and coolant all together. Both approaches show better cooling performance in pocket type cooling channel. Also both approaches show their own effectiveness in designing cooling channel of hot press forming dies.