• 대한전기학회논문지:전력기술부문A
• /
• 제51권6호
• /
• pp.302-310
• /
• 2002

This paper presents an application of a improved branch exchange (IBE) algorithm with a tie branch power (TBP) flow equation to solve the Optimal Routing problem for operation of a radial Power system including power distribution system. The main objective of the Optimal Routing problem usually is to minimize the network real power loss and to improve the voltage profile in the network. The new BE algorithm adopts newly designed methods which are composed by decision method of maximum loss reduction and new index of loss exchange in loop network Thus, the proposed algorithm in this paper can search the optimal topological structures of distribution feeders by changing the open/closed states of the sectionalizing and tie switches. The proposed algorithm has been evaluated with the practical IEEE 32, 69 bus test systems and KEPCO 148 bus test system to show favorable performance gained.

• 전기학회논문지
• /
• 제56권3호
• /
• pp.451-456
• /
• 2007

This paper presents a problem that reconfigure distribution power system using branch exchange method. Optimal reconfiguration problem calculates line loss, voltage condition about system states of all situations that become different according to line On/off status, and search for optimum composition of these. However, result is difficult to be calculated fast. Because radiated operation condition of system is satisfied using many connection and sectionalize switches in the distribution power system. Therefore, in this paper, optimization method for reducing system total loss and satisfying operating condition of radial and constraints condition of voltage is proposed using the fastest branch exchange. And optimal solution at branch exchange algorithm can be wrong estimated to local optimal solution according to initial operating state. Considering this particular, an initial operating point algorithm is added and this paper showed that optimal solution arrives at global optimal solution.

• 대한화학회지
• /
• 제55권1호
• /
• pp.7-13
• /
• 2011

전자구조의 계산에서 교환과 상관 효과에 대한 기술을 개선하기 위해서는 교환-상관범함수에 대한 개념을 명확히 하는 것이 바람직하다. 이 목적을 성취하기 위해서는 많은 그룹의 물질에 대하여 다른 이론 방법을 적용할 필요가 있다. 본 연구에서는 탄소나노튜브의 고리와 바구니 내원자들의 밀도전하를 연구하기 위하여 혼성 밀도함수 이론(DFT) 계산을 수행하였다. 핵-핵 에너지, 전자-핵 에너지와 운동에너지에 대한 교환 및 상호작용을 관찰하였으며, B3P86, B3PW91, B1B96, BLYP와 B3LYP 수준에서 계산하였다.

• 유통과학연구
• /
• 제11권6호
• /
• pp.13-19
• /
• 2013

Purpose - This study aims to predict the audit reports of listed companies on the Tehran Stock Exchange by using meta-heuristic algorithms. Research design, data, methodology - This applied research aims to predict auditors reports' using meta-heuristic methods (i.e., neural networks, the ANFIS, and a genetic algorithm). The sample includes all firms listed on the Tehran Stock Exchange. The research covers the seven years between 2005 and 2011. Results - The results show that the ANFIS model using fuzzy clustering and a least-squares back propagation algorithm has the best performance among the tested models, with an error rate of 4% for incorrect predictions and 96% for correct predictions. Conclusion - A decision tree was used with ten independent variables and one dependent variable the less important variables were removed, leaving only those variables with the greatest effect on auditor opinion (i.e., net-profit-to-sales ratio, current ratio, quick ratio, inventory turnover, collection period, and debt coverage ratio).

• Journal of Electrochemical Science and Technology
• /
• 제14권1호
• /
• pp.38-50
• /
• 2023

Proton exchange membrane fuel cell (PEMFC) is a portable and clean power generation device. The structural arrangement of the flow field has a significant influence on the delivery efficiency of PEMFC. In this article, a new bionic flow channel is designed based on the inspiration of a spider shape. The branch channel width and branch corner are studied as the focus, and its simulation is carried out by the method of computational fluid dynamics (CFD). The results show that when channel width/rib width and corner of the branch are 1.5 and 130° , respectively, it is the best numerical combination and the cell comprehensive performance is excellent. The final model using this numerical combination is compared with the traditional flow channel model to verify the advancement of this scheme.

• 정보와 통신
• /
• 제9권1호
• /
• pp.37-42
• /
• 1992

This paper presents a multi-purpose digital exchange which can be used as a private branch exchange(PBX) or a rural exchange(RX) or an exchange for the private special network. This new idea provides various features, reduced cost of installation and operation, easy expansion, replacement and relocation or reuse for another purpose at other locations.

• 대한전기학회논문지:전력기술부문A
• /
• 제49권11호
• /
• pp.566-574
• /
• 2000

This paper propose a heuristic algorithm based on the Branch-Exchange (BE) method to solve Optimal feeder Routing(OFR) problem for the distribution system planning. The cost function of the OFR problem is consisted of the investment cost representing the feeder installation and the system operation cost representing the system power loss. We propose a properly designed heuristic strategy, which can handle the horizon-year expansion planning problem of power distribution network. We also used the loop selection method which can define the maximum loss reduction in the network to reduce calculation time, and proposed a new index of power loss which is designed to estimate the power loss reduction in the BE. The proposed index, can be considered with both sides, the low voltage side and voltage side branch connected with tie one. The performances of the proposed algorithms and loss index were shown with 32, 69 example bus system.

• KIEE International Transactions on Power Engineering
• /
• 제4A권2호
• /
• pp.58-68
• /
• 2004

This paper presents an optimal routing algorithm (ORA) for maximizing voltage stability as well as for minimizing power loss in radial power systems. In the proposed ORA, a novel voltage stability index (VSI) for real-time assessment is newly introduced based on the conventional critical transmission path framework. In addition, the suggested algorithm can automatically detect the critical transmission paths resulting in voltage collapse when additional real or reactive loads are added. To implement an effective ORA, we have developed an improved branch exchange (IBE) method based on a loss calculation index and tie-branch power flow equations, which are suggested for real-time applications. The proposed algorithm has been tested with IEEE test systems as well as a large-scale power system in Korea to demonstrate its effectiveness and efficiency.

• 멤브레인
• /
• 제27권6호
• /
• pp.469-476
• /
• 2017

분리막을 이용한 분리 기술은 에너지 소요가 적다. 제올라이트를 기반으로 제작한 분리막의 경우, 결정 구조 내에 작은 분자 크기의 기공을 갖고 있어 이를 이용하여 가혹한 조건에서도 분리가 가능하기 때문에, 그 관심도가 높다. NaA (LTA 유형의 제올라이트) 제올라이트의 경우, 산업적으로 유기 용매에서 수분을 제거하는 데 많이 사용되는 데, 해당 기공 크기나 열적/수열안정성은 제올라이트 내부나 외부의 원소를 바꿔줌으로써 조절할 수 있다. 더 작은 0.28 nm 크기를 지닌 SOD 유형의 제올라이트의 경우, 수소나 물 분리에 적합하여 그 관심도가 높아지고 있으며, 이 제올라이트 유형 또한, 이온교환과 같은 방법으로 성질을 변경할 수 있다. 제올라이트는 주변 기술 및 공정 조건에 맞게 작은 분자들을 적절하게 분리할 수 있는 분리막을 창출할 수 있다는 장점을 지닌 소재이다.

• 대한전기학회논문지:전력기술부문A
• /
• 제51권11호
• /
• pp.568-576
• /
• 2002

This paper presents a new algorithm for the enhancement of voltage stability by optimal routing (OR) technique. A new voltage stability index (VSI) for optimal routing is also proposed by using theories of critical transmission path based on voltage phasor approach and equivalent impedance method. Furthermore, the proposed algorithm automatically detect the critical transmission path to critical transmission path to critical load which are faced to voltage collapse due to additional real or reactive loading. We also adopt a improved branch exchange (IBE) algorithm based on a tie branch power (TBP) flow equation to apply the OR technique. The proposed IBE algorithm for the VSI maximizing can effectively search the optimal topological structures of distribution feeders by changing the open/closed states of the sectionalizing and tie switches. The proposed algorithm has been evaluated with the practical IEEE 32, 69 bus test systems and KEPCO 148 bus test system to show favorable performance.