• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
• /
• pp.50-52
• /
• 2008

We have limited the transfer power to capital area below a certain level which is called "The Capital Area Transfer Power Limit", and calculated on every Thursday for the application next week. This level is very important in our network operation, because if this level is not set properly, our power network can be fallen under great danger in case of a fault among the transfer power line. But the calculation procedure for the limit level is so complicated and iterative that it mace us spend much time and do much work. So, when a sudden trip of the related facility to the limit level we can't recalculate the limit level fast enough. And this can drop our network reliability below our standards, therefore our network can be dangerous. To avoid this kind of problems, we have figured out a method to calculate simply the limit level. That method uses the index related to the level. We think this method can make short of the calculation procedures for the level. This paper deals with the simplified method for the calculation of the level limit.

• 대한기계학회논문집
• /
• 제13권5호
• /
• pp.1044-1051
• /
• 1989

본 연구에서는 Wu가 제시한 수학적 모델에 기초를 둔 비점성 준3차원 유동해 석에 실제 유체의 점성효과 및 2차유동 등에 의해 발생하는 손실들을 손실모델로 반영하여 그 타당성 유무를 검토하는 데 목적을 두었다.

• 한국전자파학회논문지
• /
• 제25권5호
• /
• pp.601-606
• /
• 2014

IPO(Iterative Physical Optics) 방법은 대규모 물체의 산란파를 효과적으로 계산하는 고주파 근사 방법 중 하나인 PO(Physical Optics) 방법을 반복적으로 적용하는 계산방법이다. IPO 방법은 일차(first-order) PO 방법에서는 고려하지 못하는 다중 반사를 고려할 수 있어, 산란체 표면에 여기되는 전류의 정확도를 높일 수 있다. 그러므로 산란체의 RCS(Radar Cross Section)를 보다 정확하게 예측할 수 있다. 그러나 IPO 방법은 필요한 적분방정식을 정확하게 풀지 않아 수렴성에 문제가 생긴다. 그러므로 본 논문에서는 IPO 방법의 수렴성을 조절하기 위해, 행렬연산에 사용하는 Jacobi, Gauss-Seidel, SOR(Successive Over Relaxation) 그리고 Richardson 방법을 IPO 방법에 적용하였다. 그러므로 대규모 물체의 RCS 계산을 제안된 IPO 방법을 사용하여 효율적으로 계산할 수 있다. 또, 이들의 정확도를 시뮬레이션을 통해 검증하였다.

• 천문학논총
• /
• 제24권1호
• /
• pp.1-8
• /
• 2009

A plane-parallel model of the diffuse Galactic light (DGL) is calculated assuming exponential disks of interstellar dust and OB stars, by solving exactly the radiative transfer equation using an iterative method. We perform a radiative transfer calculation for a model with generally accepted scale heights of stellar and dust distribution and compare the results with those of van de Hulst & de Jong for a constant slab model. We also find that the intensity extrapolated to zero dust optical depth has a negative value, against to the usual expectation.

• Journal of Welding and Joining
• /
• 제6권4호
• /
• pp.35-43
• /
• 1988

Welding residual stresses were calculated by two dimensional thermal elasto-plastic analysis using element method. Complicated plastic behavior during heat transfer was simulated with time. Fist, temperature distributions. To consider time varying behavior of material properties and loading and unloading processes, iterative calculation based on initial stiffness method was carried out. The method proposed by Yamata was used in time increment control which determined the accuracy of claculation. comparison with other caculated and experimental results shows fairly good agreement.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
• /
• pp.588-592
• /
• 2003

In recent years, the multilevel inverter synthesizing the output voltage with step pulse has been widely used as a solution for high power and high voltage applications. This paper proposes a simple method to obtain the conducting . angle. It is calculated by using voltage-second areas of the divided reference voltage according to the output voltage levels and these areas have influence on output step pulse waves. It is possible to reduce an amount of calculation because it is not required to solve the simultaneous equations by an iterative method. Also, the proposed method can get the conducting angle by means of on line.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 A
• /
• pp.315-317
• /
• 1999

This paper presents a method for determining of the equivalent d-q model parameters of three-phase squirrel cage induction motors. The method is based on the use of a finite-element field calculation which enables the precise slot geometry to be modelled accurately, and includes the effects of magnetic saturation of iron core. The proposed method can reduce computational costs compared with the method that needs the iterative field analysis to obtain the impedance. It is verified that the circuit inductances are shown as functions of the current.

• KEPCO Journal on Electric Power and Energy
• /
• 제5권3호
• /
• pp.181-188
• /
• 2019

본 연구에서는 발전시스템의 설계 입출력변수들을 Heat & Mass balance 계산 solver 및 최적화 알고리즘과 연계하고 반복계산 과정을 자동화함으로써 기술 및 경제적 측면을 고려한 최적의 발전시스템 Heat & Mass balance 설계를 도출하는 최적설계 자동화 기법을 개발하였다. 그리고 이에 대한 효과를 분석하기 위하여 발전소 형식별 10종에 대하여 최적설계 기법을 적용한 결과, NPV 및 IRR에 대한 개선 효과를 기대할 수 있었다.

• Structural Engineering and Mechanics
• /
• 제59권5호
• /
• pp.821-840
• /
• 2016

A simple design process is proposed for supplemental viscous dampers based on structural safety redundancy. In this process, the safety redundancy of the primary structure without a damper is assessed by the capacity and response spectra. The required damping ratio that should be provided by the supplemental dampers is estimated by taking the structural safety redundancy as a design target. The arrangement of dampers is determined according to the drift distribution obtained by performing pushover analysis. A benchmark model is used to illustrate and verify the validity of this design process. The results show that the structural safety redundancy of the structure provided by the viscous dampers increases to approximately twice that of the structure without a damper and is close to the design target. Compared with the existing design methods, the proposed process can estimate the elastic-plastic response of a structure more easily by using static calculation, and determine the required damping ratio more directly without iterative calculation or graphical process. It can be concluded that the proposed process is simple and effective.

• Structural Engineering and Mechanics
• /
• 제41권3호
• /
• pp.339-348
• /
• 2012

The slope stability analysis is usually done using the methods of calculation to rupture. The problem lies in determining the critical failure surface and the corresponding factor of safety (FOS). To evaluate the slope stability by a method of limit equilibrium, there are linear and nonlinear methods. The linear methods are direct methods of calculation of FOS but nonlinear methods require an iterative process. The nonlinear simplified Bishop method's is popular because it can quickly calculate FOS for different slopes. This paper concerns the use of inverse analysis by genetic algorithm (GA) to find out the factor of safety for the slopes using the Bishop simplified method. The analysis is formulated to solve the nonlinear equilibrium equation and find the critical failure surface and the corresponding safety factor. The results obtained by this approach compared with those available in literature illustrate the effectiveness of this inverse method.