• 제목/요약/키워드: Transfer stability

검색결과 951건 처리시간 0.04초

앵커 하중전이에 따른 사면의 안전율 비교 연구 (Comparison of Safety factor for an Anchored Slope in Accordance with the Effects of Load Transfer)

  • 김성규;김낙경;박종식;주용선;김태훈
    • 한국지반공학회논문집
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    • 제24권11호
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    • pp.55-60
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    • 2008
  • 본 논문에서는 앵커로 보강된 사면에 대한 안정해석시 앵커의 하중전이 메커니즘이 사면의 전체 안전율에 어떻게 영향을 미치는지를 알아보았다. 사면안정해석 방법에는 한계평형해석범, 유한요소해석법 및 스프레드시트를 이용하는 방법이 있으며 각각의 방법을 통해 안전율을 산정하여 서로 비교하였다. 앵커로 보강된 사면의 안정해석을 위해 가장 널리 사용되고 있는 방법은 한계평형해석 법으로 사용이 간편하다는 특징을 가지고 있다. 그러나 한계평형해석방법에서는 사면의 파괴면이 정착장을 통과하거나 정착장 바깥쪽을 지날 때에는 사면의 전체 안전율에 아무런 영향을 주지 못 하기 때문에 실제보다 보수적인 설계가 이루어질 수 있다. 따라서 본 논문에서는 각각의 해석방법을 이용하여 앵커로 보강된 사면의 안정해석을 수행하고 안전율을 비교하였다.

다공성세라믹버너의 화염안정화에 관한 연구 (A Study on the Flame Stability of Porous Ceramic Burner)

  • 이도형;윤봉석
    • 동력기계공학회지
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    • 제20권4호
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    • pp.12-18
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    • 2016
  • Typical boiler system consists of combustion chamber and heat exchanger in one housing, therefore the size of boiler system is large and the heat exchanging efficiency becomes low. At these boiler systems, because the combustible mixture fires as free flame in the combustion chamber, consequently the combusted hot gas heats the heat exchanger only as conductive and convective heat transfer. The present Porous Ceramic Burner concept is that combustion process is occurred at the gaps of the porous ceramic materials, and the heat exchanger is placed in the same porous materials. Therefore we can reduce the boiler size, and we can also use radiative heat transfer from ceramic material with conductive and convective heat transfer from combusted gas throwing the porous materials. The purpose of this study is to search the flame stability ranges at different fuel flow rate and excess air ratio burning in the $Al_2O_3$ ceramic balls. We found out the stable excess air ratio range on given combustion intensity. And we can get clean porous ceramic combustion results compared with free flame.

Hopf Bifurcation Study of Inductively Coupled Power Transfer Systems Based on SS-type Compensation

  • Xia, Chenyang;Yang, Ying;Peng, Yuxiang;Hu, Aiguo Patrick
    • Journal of Power Electronics
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    • 제19권3호
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    • pp.655-664
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    • 2019
  • In order to analyze the nonlinear phenomena of the bifurcation and chaos caused by the switching of nonlinear switching devices in inductively coupled power transfer (ICPT) systems, a Jacobian matrix model, based on discrete mapping numerical modeling, is established to judge the system stability of the periodic closed orbit and to study the nonlinear behavior of Hopf bifurcation in a system under full resonance. The general flow of the parameter design, based on the stability principle for ICPT systems, is proposed to avoid the chaos and bifurcation phenomena caused by unreasonable parameter selection. Firstly, based on the state equation of SS-type compensation, a three-dimensional bifurcation diagram with the coupling coefficient as the bifurcation parameter is established with a numerical simulation to observe the nonlinear phenomena in the system. Then Filippov's method based on a Jacobian matrix model is adopted to deduce the boundary of stable operation and to judge the type of the bifurcation in the system. Then the general flow of the parameter design based on the stability principle for ICPT systems is proposed through the above analysis to realize stable operation under the conditions of weak coupling. Finally, an experimental platform is built to confirm the correctness of the numerical simulation and modeling.

Optimal Shunt Compensation for Improving Voltage Stability and Transfer Capability in Metropolitan Area of the Korean Power System

  • Choi, YunHyuk;Lee, Byongjun;Kim, TaeKyun
    • Journal of Electrical Engineering and Technology
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    • 제10권4호
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    • pp.1502-1507
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    • 2015
  • This paper deals with shunt compensation to eliminate voltage violation and enhance transfer capability, which is motivated towards implementation in the Korean power system. The optimal shunt compensation algorithm has demonstrated its effectiveness in terms of voltage accuracy and reducing the number of actions of reactive power compensating devices. The main shunt compensation devices are capacitor and reactor. Effects of control devices are evaluated by cost computations. The control objective at present is to keep the voltage profile of a key bus within constraints with minimum switching cost. A robust control strategy is proposed to make the control feasible and optimal for a set of power-flow cases that may occurs important event from system. Case studies with metropolitan area of the Korean power system are presented to illustrate the method.

The Onset of Natural Convection and Heat Transfer Correlation in Horizontal Fluid Layer Heated Uniformly from Below

  • Kim, Min-Chan;Kim, Sin
    • Journal of Mechanical Science and Technology
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    • 제15권10호
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    • pp.1451-1460
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    • 2001
  • The critical condition of the onset of buoyancy-driven convective motion of uniformly heated horizontal fluid layer was analysed by the propagation theory which transforms the disturbance quantities similarly. The dimensionless critical time, $\tau$$\sub$c/, is obtained as a function of the Rayleigh number and the Prandtl number. Based on the stability criteria and the boundary-layer instability model, a new heat transfer correlation which can cover whole range of Rayleigh number was derived. Our theoretical results predict the experimental results quite reasonably.

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다수의 열원을 가진 채널의 경사각이 전자장비의 열적 안정성에 미치는 영향 (The effect of Inclined angle of Channel with multi heat source on Thermal Stability of Electronic Equipment)

  • 방창훈;김정수;예용택
    • 한국안전학회지
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    • 제16권3호
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    • pp.12-18
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    • 2001
  • The objective of the present work is to examine the effect of inclined angle of channel with multi heat source on thermal stability of electronic equipment. The heat sources are mounted on both sides of channel walls by two kinds of configuration such as the zig-zag md symmetric on. Conductive heat transfer was estimated by using of thermocouples and heat flux sensor. Thus, convective heat transfer and mean Nusselt number could be obtained. With increased inclined angle, the convective heat transfer coefficient was decreased. When inclined angle was smaller than 30 degree, The average Nusselt number of Big-zag configuration was larger than that of symmetric. Furthermore, when protruding ration was 0.082, the temperature was strongly affected by inclined angle. whereas, when protruding ration was 0.25, the temperature was strongly affected by heat source configuration.

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과도 안정도를 고려한 수송능력 산정 알고리즘의 개발에 관한 연구 (A Study on Development of Power Transfer Capability Calculation Algorithm Considering Transient Stability)

  • 김용하;이범;최상규;조성린;이재걸;오석현;김동근
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2003년도 하계학술대회 논문집 A
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    • pp.95-97
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    • 2003
  • The cost losing synchronous through a transient instability is extremely high in modern power systems. This paper presents a power transfer capability calculation algorithm considering transient stability. The theoretical development is straightforward: dynamic equations are converted to numerically equivalent algebraic equation and then integrated into the standard formulation for power transfer capability calculation.

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과도 안정도를 고려한 수송능력 산정 알고리즘의 개발에 관한 연구 (A Study on Development of Power Transfer Capability Calculation Algorithm Considering Transient Stability)

  • 김용하;최상규;이범;조성린;오석현;김동근
    • 대한전기학회논문지:전력기술부문A
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    • 제55권1호
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    • pp.24-28
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    • 2006
  • This paper presents a power transfer capability calculation algorithm considering transient stability, The theoretical development is straightforward: dynamic equations are converted to numerically equivalent algebraic equation and then integrated into the standard formulation for power transfer capability calculation. The proposed method is applied to IEEE-24 Reliability Test System and the results shows the effectiveness of the method.

Probabilistic Assessment of Total Transfer Capability Using SQP and Weather Effects

  • Kim, Kyu-Ho;Park, Jin-Wook;Rhee, Sang-Bong;Bae, Sungwoo;Song, Kyung-Bin;Cha, Junmin;Lee, Kwang Y.
    • Journal of Electrical Engineering and Technology
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    • 제9권5호
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    • pp.1520-1526
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    • 2014
  • This paper presents a probabilistic method to evaluate the total transfer capability (TTC) by considering the sequential quadratic programming and the uncertainty of weather conditions. After the initial TTC is calculated by sequential quadratic programming (SQP), the transient stability is checked by time simulation. Also because power systems are exposed to a variety of weather conditions the outage probability is increased due to the weather condition. The probabilistic approach is necessary to evaluate the TTC, and the Monte Carlo Simulation (MCS) is used to accomplish the probabilistic calculation of TTC by considering the various weather conditions.

과도 안정도를 고려한 수송능력 산정 알고리즘의 개발에 관한 연구(II) (A Study on Development of Power Transfer Capability Calculation Algorithm Considering Transient Stability (II))

  • 김용하;이범;최상규;오석현;조성린;김미예
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2004년도 추계학술대회 논문집 전력기술부문
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    • pp.128-130
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    • 2004
  • The cost losing synchronous through a transient instability is extremely high in modem power systems. This paper presents a power transfer capability calculation algorithm considering transient stability. The theoretical development is straightforward: dynamic equations are converted to numerically equivalent algebraic equation and then integrated into the standard formulation for power transfer capability calculation. The proposed method is applied to IEEE-24 Reliability Test System and the results shows the effectiveness of the method.

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