• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.900-902
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• 1997

Stabilization of Power systems is investigated using a proportional-integral power system stabilizer(PI PSS). Time division PI PSS is examined in this paper. Two approaches are presented for determining the optimal stabilizer gains of the proposed PI PSS. Simulation results show that the proposed PI PSS yields better system dynamic performance and stability than the sub-optimal stabilizer in the sense of having greater damping in response to a step disturbance.

• Journal of Computational Design and Engineering
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• v.3 no.2
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• pp.112-120
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• 2016

This paper proposes eight groups of twenty nine scoring criteria that can help designers and practitioners to compare and select an appropriate methodology for a certain problem in designing product service system (PSS). PSS has been researched for more than a decade and is now becoming more and more popular in academia as well as industry. Despite that fact, the adoption of PSS is still limited for its potential. One of the main reasons is that designing PSS itself is a challenge. Designers and developers face difficulties in choosing appropriate PSS design methodologies for their projects so that they can design effective PSS offerings. By proposing eight groups of twenty nine scoring criteria, this paper enables a "step by step" process to identify the most appropriate design methodology for a company's PSS problem. An example is also introduced to illustrate the use of the proposed scoring criteria and provide a clear picture of how different design methodologies can be utilized at their best in terms of application.

• Research in Community and Public Health Nursing
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• v.32 no.4
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• pp.540-554
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• 2021

Purpose: Most of the currently used concepts and measurements of social support have been relevant for general population. The main purpose of this study is to conduct the concept analysis of perceived social support(PSS) of family caregivers for people with dementia. Methods: This study adopted the Walker and Avant concept analysis methodology. Results: Findings from this concept analysis suggested four defining attributes of PSS of family caregivers for people with dementia: 1) PSS is help or assistance that family caregivers perceive as available when needed; 2) PSS is offered through socio-ecological structure; 3) PSS has a specific function to meet the needs of family caregivers; and 4) PSS includes quality aspects where family caregivers choose, use, or evaluate it. Borrowing from the socio-ecological model, this study proposed the structural aspects of PSS. This study also identified functional aspects of PSS, such as emotional support, informational support, appraisal support, and practical support. Finally, this study assessed quality aspects of PSS, such as satisfaction, timeliness, usefulness, accessibility, and coordination. Conclusion: Focusing on family caregivers for people with dementia, we proposed a new model of PSS. The present study helped refine and clarify the concept of PSS of family caregivers for people with dementia. The results of this study may also contribute to promoting the development of more effective instruments for the concept.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.177-182
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• 1994

In this paper, an output feedback adaptive variable structure control scheme is presented for stabilization of large scale power systems. An additional input signal which is called a power system stabilizer(PSS) is needed to improve the stability of a power system and to maintain the synchronization of generators. The proposed PSS scheme does not require a priori knowledge of uncertainty bounds. It is guaranteed that the closed-loop system is globally uniformly ultimately bounded by the Lyapunov stability theory. Simulation results for a multimachine power system are given to show the feasibility of the proposed scheme and the superiority of the proposed PSS in comparison with the conventional lead-lag PSS of PID-type.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.4
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• pp.197-207
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• 2001

In this paper, design problem of QFT-PSS using Genetic Algorithm(GA) is investigated for power systems with parameter variation and disturbance uncertainties. A robust controller for uncertain power systems can be designed automatically such that the cost of feedback is minimized and all robust stability and performance specifications are satisfied. It is shown that the proposed design method not only automates loop shaping but also improves design quality and improves the quality with a reduced order controller. The robustness of the proposed controller has been investigated on a single machine infinite bus model. The results are shown that the proposed QFT-PSS using GA is more robust tan conventional PSS.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.5
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• pp.337-342
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• 1989

Since the late 1960s, the selection of the parameters of power system stabilizer (PSS) to damp out sustained low frequency oscillation of power generators in the steady state has been an active research area. This paper presents a new approach to select the optimal PSS parameters using the sensitivity of the quadratic performance with respect to the PSS parameters. The proposed algorithm has been applied to Seo-Cheon fossil power plant.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.168-176
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• 2015

Trends of integrating products and services lead to the emergence of Product-Service System (PSS). To implement and embody a PSS solution in new product development, a comprehensive design framework is allowed designers to facilitate the design factors of the PSS in complex business environments. A physical product, containing functionalities for services, is the role of medium between customers and a manufactures. Customers can access those metaphysical interfaces to utilize the product fully or expand its performances. The PSS is aiming to prolong its lifecycle while maintaining its expected quality. Since the quality can be represented as a measure which belongs to user's perspective, guaranteeing certain level of quality can be interpreted to sustaining customer satisfaction. The objective of this paper is to propose a PSS design framework to identify design factors for developing products and services by integrating object-oriented concepts and blueprinting in context of a business ecosystem. The proposed model is developed based on relationship products and services matching with their design factors. The products and the services are then brought together to form a PSS. Functions and processes can be categorized to identify the design factors in different levels using the object-oriented concepts. Objected-oriented concepts provide PSS analysis tools for describing a business process or a workflow process in the PSS. The blueprint is used to identify the relationships between the products functions and the service processes that are offered as part of a job. To demonstrate of the effectiveness of the proposed model, we use a case study involving a smart phone.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.486-489
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• 2002

This paper proposes a tabu search (TS) algorithm to optimal weight selection in design of robust H$_{\infty}$ power system stabilize. (PSS), In H$_{\infty}$ control design, the weight selection and the representation of system uncertainties are the major difficulties. To cope with these problems, TS is employed to automatically search for the optimal weights. On the other hand, the normalized coprime factorization (NCF) is used. The H$_{\infty}$ controller can be directly developed without ${\gamma}$-iteration. Also, the pole-zero cancellation phenomena are prevented. The performance and robustness of the proposed PSS under different loading conditions are investigated in comparison with a robust tuned PSS by examining the case of a single machine infinite bus (SMIB) system. The simulation results illustrate the effectiveness and robustness of the proposed PSS.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1873-1881
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• 2014

This paper deals with the design of multi-machine power system stabilizers (PSSs) and Static var compensator (SVC) using Modified shuffled frog leaping algorithm (MSFLA). The effectiveness of the proposed scheme for optimal setting of the PSSs and SVC controllers has been attended. The PSSs and SVC controllers designing is converted to an optimization problem in which the speed deviations between generators are involved. In order to compare the capability of PSS and SVC, they are designed independently once, and in a coordinated mode once again. The proposed method is applied on a multi-machine power system under different operating conditions and disturbances to confirm the effectiveness of it. The results of tuned PSS controller based on MSFLA (MSFLAPSS) and tuned SVC controller based on MSFLA (MSFLA SVC) are compared with the Strength pareto evolutionary algorithm (SPEA) and Particle swarm optimization (PSO) based optimized PSS and SVC through some performance to reveal its strong performance.

• Journal of Electrical Engineering and information Science
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• v.2 no.3
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• pp.88-94
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• 1997

This paper presents the sliding mode observer-model following (SMO-MF) power system stabilizer(PSS) for unmeasurable state variables. This SMO-MF PSS is obtained by combining the sliding mode-model following (SM-MF) including closed-loop feedback(CLF) with the full-order observer(FOO). The control input of the proposed MO-MF PSS is derived by Lyapunov's second method to determine a control input that keeps the system stable for unmeasurable plant state variables. Simulation results show that the proposed SMO-MF PSS including CLF is able to reduce the low frequency oscillation and to achieve asymptotic tracking error between the reference mode state and the estimated plant state at different initial conditions.