• Proceedings of the KIEE Conference
• /
• 대한전기학회 1998년도 하계학술대회 논문집 C
• /
• pp.871-874
• /
• 1998

It is most important in small signal stability analysis of large scale power systems to compute only the dominant eigenvalues selectively with numerical stability and efficiency. Hessenberg process is numerically very stable and identifies the largest eigenvalues in magnitude. Hence, transformed system matrix must be used with the process. Inverse transformation with complex shift provides high selectivity centered on the shift, but does not possess the desired property of computing the dominant mode first. Thus, advantage of high selectivity of the transformation can be fully utilized only when the complex shift is given close to the dominant eigenvalues. In this paper, complex shift is determined by Fourier transforming the results of dynamic simulation with PTI's PSS/E transient simulation program. The convergence in Hessenberg process is accelerated using the iterative scheme. Overall, a numerically stable and very efficient small signal stability program is obtained. The stability and efficiency of the program has been validated against New England 10-machines 39-bus system and KEPCO system.

• Journal of Korea Society of Industrial Information Systems
• /
• 제7권4호
• /
• pp.90-99
• /
• 2002

Grid makes it possible to cooperate with other network area by sharing and using distributed resources. In order to manage effectively large-scale Grid network resources, Grid NOC needs monitoring architecture that can manage distributed resources in one time. Being restricted within specific managing area conventional network management system has limitation in extension of managing area and in general management of heterogeneous resource. In this paper, we design a monitoring architecture that can take in the situation and has scalability. In the monitoring architecture the network areas publish information in a common directory service, and then Grid NOC can connect to the network areas directly by using this information. Therefore, it makes us possible to manage overall large-scale resource of Grid network reducing load.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제8권3호
• /
• pp.857-872
• /
• 2014

Recent researches reveal that great benefit can be achieved for data gathering in wireless sensor networks (WSNs) by employing mobile data collectors. In order to balance the energy consumption at sensor nodes and prolong the network lifetime, a multi-track large-scale mobile data collection mechanism (MTDCM) is proposed in this paper. MTDCM is composed of two phases: the Energy-balance Phase and the Data Collection Phase. In this mechanism, the energy-balance trajectories, the sleep-wakeup strategy and the data collection algorithm are determined. Theoretical analysis and performance simulations indicate that MTDCM is an energy efficient mechanism. It has prominent features on balancing the energy consumption and prolonging the network lifetime.

• Aerospace Engineering and Technology
• /
• 제7권2호
• /
• pp.38-45
• /
• 2008

It is challenging to build the integrated information system for a large scale cooperative R & D project. To develop the aircraft program which especially has several leading agencies and is supported by many demestic/foreign participating companies, the common data flow in harmony is the core factor to achieve a development goal. For this, the development are carried out maintaining the existing management systems of agencies and companies. As a first step, the standard for the common data information and the classification category of technical data are defined. Second, the work flow standards are also set. Based on the foundation, the efficient technical data management system are built including the function of storage, inquiry, revision, link, approval, submission, etc.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권4호
• /
• pp.1460-1478
• /
• 2020

This paper proposes a novel anti-collision protocol for large-scale RFID tags identification, named Bi-response Collision Tree Protocol (BCT). In BCT, two group of tags answer the reader's same query in two response-cycles respectively and independently according to the bi-response pattern. BCT improves the RFID tag identification performance significantly by decreasing the query cycles and the bits transmitted by the reader and tags during the identification. Computation and simulation results indicate that BCT improves the RFID tag identification performance effectively, e.g. the tag identification speed is improved more than 13.0%, 16.9%, and 22.9% compared to that of Collision Tree Protocol (CT), M-ary Collision Tree Protocol (MCT), and Dual Prefix Probe Scheme (DPPS) respectively when tags IDs are distributed uniformly.

• Korean Management Science Review
• /
• 제15권2호
• /
• pp.125-142
• /
• 1998

The aggregation on linear large-scale dynamic systems is examined in this paper and a "two-step" approach is proposed. In this procedure, the aggregated system consists of two subsystems. The first subsystem represents aggregation through the retainment of dominant eigenvalues of the original system, leading to a first approximation of the desired output of the original system. The purpose of augmenting it with a second subsystem is to provide an estimation of the error on the first approximation, thus permitting a second correction to the output approximation and resulting in an output approximation of greater accuracy. Optimization techniques are discussed for the determination of unknown parameters in the aggregated system. These techniques use minimization principles of certain suitable performance indices and are developed for both single input-single output and multiple input-multiple output system. Numerical examples illustrating these procedures are given and the results are compared with those obtained using existing methods. Finally, a pharmacokinetics problem is studied from the aggregation point of view.

• KEPCO Journal on Electric Power and Energy
• /
• 제5권4호
• /
• pp.343-347
• /
• 2019

When referring to weight, volume, and efficiency, a SuperConducting Synchronous Generator (SCSG) is definitely superior to conventional generators as a large-scale wind power generation system. The SCSG is connected to a full power converter that transmits the energy from the SCSG to the power grid. To reduce the current stress and system cost, the SCSG which has nine-phase armature windings with three converters is used. This paper deals with a comparative analysis of 10 MW superconducting wind power generators with three-phase and nine-phase armature windings. The stator windings of SCSGs are of various types. Using the finite element method, SCSGs are analyzed and compared in terms of the weight and volume of SCSGs, the total length of the superconducting wire, harmonics, torque performance, and efficiency. The analyzed results will be effectively utilized to design large-scale superconducting generators for wind power generation systems.

• Proceedings of the KIEE Conference
• /
• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
• /
• pp.226-228
• /
• 2007

This paper proposes Nonlinear Interior Point Method (NIPM) including discrete control variables optimal power flow formulations. The algorithm utilizes the robustness in terms of starting point and fast convergence for large scale power system of NIPM and an introduction of rounding penalty function which is augmented in the Lagrangian function to handle discrete control variables. The derived formulation shows a simplified approach to deal with discrete control problems which is implementable in real large scale systems.

• Proceedings of the KIEE Conference
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.694-695
• /
• 2011

The recent concerns over the threat of global climate change and the requirements of national reduction of $CO_2$ emission have led to the diversification of energy resources and a large scale integration of renewable resources. In these circumstances, the policy decision currently made by the government sector includes several programs to promote the equipment of large scale generating assets to use wind energy. However, the power systems and wind farms need such innovative operation scheme schemes that maintain an adequate level of system security for continuing growth of renewable resources. This paper presents a method for determining optimal operating points for wind farms by making use of a nonlinear interior point method.

• Journal of Korea Technology Innovation Society
• /
• 제6권3호
• /
• pp.358-372
• /
• 2003

본 연구에서는 일관제철 공정의 철강산업과 같은 대규모 기계설비 집약적 산업 환경에 적합한 기술지식 경영시스템에 대해 고려하고자 한다. 기술경쟁력 확보를 위한 철강업체의 전략적 기술경영은 핵심기술에 대한 지식경영 활동과 연계될 때 비로소 시너지효과를 극대화할 수 있다. 또한 철강업체의 지식경영은 암묵적 혹은 형식적 제철공정 기술지식의 창출, 획득 및 공유 등의 활동을 통해 활성화되어야 한다. 본 연구에서는 먼저 철강산업 현장의 기술지식 관리대상으로 조업설비 프로세스 및 무형 지식자산의 범위를 정의하고, 일관제철 공정의 핵심기술 로드맵에 따라 기술지식 경영활동에 적합한 계층적 지식경영 조직구조를 구축하고자 한다. 또한 제철공정 노하우 등과 같이 암묵적 기술지식을 획득하고 이를 공유할 수 있는 형태로 변환하기 위한 기술지식 획득 방법론을 수립하고 이를 기초로 인터넷에 기반을 둔 제철공정 기술지식 경영시스템을 구축하고자 한다.