• KIEE International Transactions on Power Engineering
• /
• 제3A권3호
• /
• pp.161-167
• /
• 2003

This paper presents a study performed to investigate the steady-state operational strategies of UPFCs in the Jeollanam-Do system in Korea. The objective of the study was to determine the UPFC operating points under normal and contingency conditions. The study consists of developing load flow models to simulate different load levels with and without UPFCs in the system, assessing the effectiveness of UPFCs by contingency analysis, and introducing optimal corrective actions for removing voltage problems caused by contingencies. The paper describes analytical tools, models and approach. It also includes analysis and discussion of the study results. The paper contributes to the area of transmission operational studies with FACTS applications.

• Asia pacific journal of information systems
• /
• 제3권1호
• /
• pp.190-213
• /
• 1993

The information revolution is sweeping through the global economy. Information technology is transforming the structure of competition. The successful implementation of information technology is dependent on the effectiveness of information systems planning. However, it is very difficult to select an appropriate methodology for information systems planning given an organization situation. A contingency model is proposed on the selection of an appropriate approach depending upon the organizational situation. Although the contingency framework is not yet theoretically proved, the approaches suggested here turned out to be of benefit to the cases of the two real world projects studied. These approaches attempt to combine Business Systems Planning of IBM and Critical Success Factors in two different manners to make planning process more efficient and effective.

• 국제학술발표논문집
• /
• The 2th International Conference on Construction Engineering and Project Management
• /
• pp.106-118
• /
• 2007

Little attention has been focussed on a precise definition and evaluation mechanism for project management risk specifically related to contractors. When bidding, contractors traditionally price risks using unsystematic approaches. The high business failure rate our industry records may indicate that the current unsystematic mechanisms contractors use for building up contingencies may be inadequate. The reluctance of some contractors to include a price for risk in their tenders when bidding for work competitively may also not be a useful approach. Here, instead, we first define the meaning of contractor contingency, and then we develop a facile quantitative technique that contractors can use to estimate a price for project risk. This model will help contractors analyse their exposure to project risks; and also help them express the risk in monetary terms for management action. When bidding for work, they can decide how to allocate contingencies strategically in a way that balances risk and reward.

• Journal of Electrical Engineering and Technology
• /
• 제12권2호
• /
• pp.541-548
• /
• 2017

An increasing concern is paid to short-term voltage stability with the growth of penetration of induction motor loads. Reactive power reserve(RPR) of power system is critical to improve voltage stability. A definition of short-term voltage stability-related RPR(SVRPR) is proposed. Generators vary their contributions to voltage stability with their location and system condition, etc. Voltage support coefficient based on the second-order trace sensitivity method is proposed to evaluate SVRPR's contribution to short-term voltage stability. The evaluation method can account for the generator's reactive support in transient process and the contingency severity. Then an optimization model to improve short-term voltage stability is built. To deal with multiple contingencies, contingency weight taking into account both its probability and severity is proposed. The optimization problem is solved by primal dual interior point method. Testing on IEEE_39 bus system, it is indicated that the method proposed is effective. Short-term voltage stability is improved significantly by the way of SVRPR optimization. Hence, the approach can be used to prevent the happening of voltage collapse during system's contingency.

• 대한전기학회논문지:전력기술부문A
• /
• 제49권6호
• /
• pp.305-311
• /
• 2000

This paper presents a hybrid algorithm for solving optimal power flow(OPF) in order to enhance a systems capability to cope with outages, which is based on combined application of evolutionary computation and local search method. The efficient algorithm combining main advantages of two methods is as follows : Firstly, evolutionary computation is used to perform global exploitation among a population. This gives a good initial point of conventional method. Then, local methods are used to perform local exploitation. The hybrid approach often outperforms either method operating alone and reduces the total computation time. The objective function of the security constrained OPF is the minimization of generation fuel costs and real power losses. The resulting optimal operating point has to be feasible after outages such as any single line outage(respect of voltage magnitude, reactive power generation and power flow limits). In OPF considering security, the outages are selected by contingency ranking method(contingency screening model). The OPF considering security, the outages are selected by contingency ranking method(contingency screening model). The method proposed is applied to IEEE 30 buses system to show its effectiveness.

• 대한전기학회논문지:전력기술부문A
• /
• 제55권5호
• /
• pp.202-213
• /
• 2006

This paper presents a new approach for optimal dispatch of energy and frequency regulation reserve considering contingency in a competitive electricity market. It is necessary to introduce the reserve market with the spot energy market for operating efficiently and obtaining the security of the electricity market. However, the reserve market is closely connected with the energy market since the energy and reserve are produced from the same resources. Thus, it is inevitable to co-optimize the energy and ancillary service for efficient operation of energy and ancillary service market. Therefore, this paper proposes a new method for optimal dispatch of energy and frequency regulation reserve considering n-1 contingency of generator and transmission line using constraints and sensitivity based on AC power flow To verify the effectiveness of the proposed method, the numerical studies have been performed for 5-bus sample system and modified IEEE 14-bus system.

• 농촌지도와개발
• /
• 제8권2호
• /
• pp.235-244
• /
• 2001

The objectives of this study were to inquire the theories associated with YLD (Youth Leadership Development), and to draw implications for improving youth leadership abilities, The results of the inquiry revealed the theories associated with YLD as follows; 1. All youth have leadership potential and abilities, but there were few programs to improve it. 2. Activity-Observation-Reflection model of Hughes, Ginnett & Curphy(1993) and Awareness-Interaction-Mastery model of Linden & Fertman(1998) were the best effective YLD models. 3. Situational contingency approach was very appropriate theory associated with YLD. 4. The learning of leadership skills had occurred within an educational context known as experiential learning, so it was the best method of YLD.

• Communications for Statistical Applications and Methods
• /
• 제5권3호
• /
• pp.905-926
• /
• 1998

We propose a modified mid P-value method to reduce the conservativeness for the inference of conditional associations in three-way contingency tables. This improves the ordinary mfd P-value method. For $2{\times} 2${\times} K$ tables, we propose confidence intervals for an assumed common odds ratio based on inverting two separate one-sided tests using the modified mid P-value. Also, an alternative and usually even better ways of constructing intervals, based on Inverting a two-sided test, are presented. The actual probability of coverage of a 100($1-\alpha$)% confidence interval is centered about the nominal level, but the modified mid P-value approach gives actual coverage probability even closer to the nominal level than the ordinary mid P-value approach.

• 지식경영연구
• /
• 제9권1호
• /
• pp.23-38
• /
• 2008

This study develops a framework and instruments to diagnose the current knowledge management(KM) status of an organization and to suggest future KM implementation directions. Based on the comprehensive review of KM literature and KM case studies, we derive three main aspects(strategic, social and technical aspect) and seven critical factors(KM strategy, knowledge worker, organizational strucuture, organizational culture, KM processe, organizational knowledge, and information technology) for the successful KM implementation. The instruments developed in this study include every specific measurement items of each critical success factor, which are expected to help not only suggest a context-sensitive KM strategy but also evaluate current KM status of a designated organization. By introducing two dimensions of KM evaluation(effectiveness and necessity), a more holistic and contingent view of KM can be assured. Academic contributions as well as practical implications are discussed. Study limitations and future research directions are also provided.

• 전기학회논문지
• /
• 제57권8호
• /
• pp.1334-1341
• /
• 2008

This paper introduces an approach of Hybrid Particle Swarm Optimization(HPSO) for a security-constrained economic dispatch(SCED) with line flow constraints. To reduce a early convergence effect of PSO algorithm, we proposed HPSO algorithm considering a mutation characteristic of Genetic Algorithm(GA). In power system, for considering N-1 line contingency, we have chosen critical line contingency through a process of Screening and Selection based on PI(performance Index). To prove the ability of the proposed HPSO in solving nonlinear optimization problems, SCED problems with nonconvex solution spaces are considered and solved with three different approach(Conventional GA, PSO, HPSO). We have applied to IEEE 118 bus system for verifying a usefulness of the proposed algorithm.