• JOURNAL OF ELECTRICAL WORLD
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• no.10 s.214
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• pp.34-46
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• 1994

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1659-1663
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• 1991

A new control design methodology is presented here which is based on a nonlinear time-series reference model. It is indicated by highly nonlinear simulations that such designs successfully stabilize troublesome aircraft maneuvers undergoing large changes in angle of attack as well as large electric power transients due to line faults. In both applications, the nonlinear controller was significantly better than the corresponding linear adaptive controller. For the electric power network, a flexible a.c. transmission system (FACTS) with series capacitor power feedback control is studied. A bilinear auto-regressive moving average (BARMA) reference model is identified from system data and the feedback control manipulated according to a desired reference state. The control is optimized according to a predictive one-step quadratic performance index (J). A similar algorithm is derived for control of rapid changes in aircraft angle of attack over a normally unstable flight regime. In the latter case, however, a generalization of a bilinear time-series model reference includes quadratic and cubic terms in angle of attack. These applications are typical of the numerous plants for which nonlinear adaptive control has the potential to provide significant performance improvements. For aircraft control, significant maneuverability gains can provide safer transportation under large windshear disturbances as well as tactical advantages. For FACTS, there is the potential for significant increase in admissible electric power transmission over available transmission lines along with energy conservation. Electric power systems are inherently nonlinear for significant transient variations from synchronism such as may result for large fault disturbances. In such cases, traditional linear controllers may not stabilize the swing (in rotor angle) without inefficient energy wasting strategies to shed loads, etc. Fortunately, the advent of power electronics (e.g., high-speed thyristors) admits the possibility of adaptive control by means of FACTS. Line admittance manipulation seems to be an effective means to achieve stabilization and high efficiency for such FACTS. This results in parametric (or multiplicative) control of a highly nonlinear plant.

• Survey Research
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• v.11 no.3
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• pp.57-79
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• 2010

This study evaluated the policy performance of i) Public Notice of Critical Information, ii) Substantiation of Facts in Labeling and Advertising, iii) Temporary Injunctions, and iv) Advertisement Correcting Misrepresented Facts, which were main policies belonged to Fair Labeling and Advertising Act(hereinafter referred to as "FLA Act"). The data was collected by visiting 76 persons personally, who were consumer policy and law experts, labeling and advertising staffs of corporations, and persons in charge of policies including public officials dealing with consumer policies at Korea Fair Trade Commission, while using a structured questionnaire at the same time. The survey was performed to examine the general policy performance and evaluation the results of FLA Act by evaluation methods. The results of the analysis are comprehensively summarized as follows. There were differences in the ranking of policies evaluated by labeling and advertising staffs of corporations and persons in charge of policies according to evaluation methods, and, in Simple Evaluation, higher scores were gained compared to Weighted Evaluation which reflected weighted values or Fuzzy Evaluation. The result shows that evaluation results can vary in policy performance evaluation according to evaluation methods.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.353-362
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• 2010

This paper presents a centralized control algorithm for power system performance in the Korean power system using Flexible AC Transmission Systems (FACTS) devices. The algorithm is applied to the Korean power system throughout the metropolitan area in order to alleviate inherent stability problems, especially concerns with voltage stability. Generally, control strategies are divided into local and centralized control. This paper is concerned with a centralized control strategy in terms of the global system. In this research, input data of the proposed algorithm and network data are obtained from the SCADA/EMS system. Using the full system model, the centralized controller monitors the system condition and decides the operating point according to the control objectives that are, in turn, dependent on system conditions. To overcome voltage collapse problems, load-shedding is currently applied in the Korean power system. In this study, the application of the coordination between FACTS and switch capacitor (SC) can restore the solvability without load shedding or guarantee the FV margin when the margin is insufficient. Optimal Power Flow (OPF) algorithm, for which the objective function is loss minimization, is used in a stable case. The results illustrate examples of the proposed algorithm using SCADA/EMS data of the Korean power system in 2007.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.3
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• pp.624-631
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• 2011

In this paper, the RCF method is used in sensitivity analysis problems of the discrete power systems including both series FACTS equipments such as TCSC in transmission lines and generator controllers such as Exciter and PSS in generator terminal. To apply the RCF method in small signal stability problems of discrete power systems, state transition equations of controllers and TCSC are derived and the sensitivity calculation algorithm using state transition equations in discrete time domain is devised. The results of eigenvalue analysis showed that the variations of eigenvalues after periodic switching operations of TCSC can be calculated exactly by the RCF method and the change of firing angles in TCSC have important effect to determine the stability of power systems.

• Corrosion Science and Technology
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• v.19 no.3
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• pp.131-137
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• 2020

A number of piping components in the secondary system of nuclear power plants (NPPs) are exposed to aging mechanisms, such as flow-accelerated corrosion (FAC), cavitation, flashing, solid particle erosion, and liquid droplet impingement erosion. Those mechanisms may lead to thinning, leaking, or rupture of the components. Due to the pipe ruptures caused by wall thinning in Surry unit 2 in the USA in 1986 and Mihama unit 3 in Japan in 1994, pipe wall thinning management has emerged as one of the most important issues in the nuclear industry. To manage pipe wall thinning, a foreign program has been utilized for NPPs in Korea since 1996. As our experience and knowledge of pipe wall thinning management have accumulated, our program needs to reflect our experience, requests from users, and the result of recent experiments using Flow Accelerated Corrosion Testing System (FACTS). FACTS is the empirical experimental facility developed by Korea Atomic Energy Research Institute (KAERI) for tests. Accordingly, KEPCO-E&C developed a 3D-based pipe wall thinning management program called ToSPACE in 2016. This paper describes a comparison between the FAC analysis results using ToSPACE and the experimental results using FACTS to verify their applicability to pipe wall thinning management in NPPs.

• The Korean Journal of Archival Studies
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• no.11
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• pp.123-143
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• 2005

1. Introduction : From the Memorial to the Records, From the Records to the Archives 2. Archivists and Historians : the Records Keeping, Appraisal and Selection 3. Records and Historical Materials in the Historical Narrative 4. the Relation of the Facts and Theory in the History 5. Conclusion In this essay I considered the relations of records and history, namely the process on the selection and choice from the records to the archives and the historical materials and in the process the role on the archivists and historians and difference and the relation of the facts and theory in the history. Archival science posits that an archives is the whole of the documents made or received in the course of purposeful activity, and of the relationships among those documents. Archival theory posits that it is the primary function of the archivists to maintain unbroken, continuing custody of societal archives, and to protect their integrity by keeping them physically and intellectually uncorrupted. The ultimate purpose of archival endeavors is to hand down to the next generations a reliable, trustworthy, and complete testimony of societal actions so that they can constitute sources of, and foundations for, future decision making. However, historical science searches for the truth in the historical facts, explains the cause and origin of the matters and reflects on th knowledge about the why and how the events happened. And history is firmly rooted on the philosophy. The goal of historian is analysing the nature of meaning of past in the society and tracing up the change and process of the transition. Archival science means historical source studies and other related disciplines. On the other hand archival management is the principle of respect for original order and the importance of original forms and conditions. Thus the relations between archival science and archives management are not one-sided but mutual. Archival science and historical studies, archivists and historians need to link more closely in order to hand down the contemporary memorial, the common memorial of mankind to the future.

• Journal of English Language & Literature
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• v.56 no.6
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• pp.1091-1103
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• 2010

Absalom, Absalom! is not only about family history but also about the nature of reconstructing history. Faulkner shows us what will happen if we give too much credit to the person having the authority; he first makes us listen to Rosa, so we just listen without doubt until we arrive at the question of the objectivity of her narration, when we get to know Sutpen's design. Meanings of "facts" change depending on who perceives the facts. The incremental repetition of the narrative in the novel resembles the process of our thinking mind and the process of history being constructed. Time is a significant element in determining the meaning of an event, not only because the event cannot be understood without its social, cultural context of the contemporary, but also because only the later events make it possible for the perceiver to categorize it in its proper place in history. Furthermore, through his narrative strategy, Faulkner suggests that imagination play a large part in recreating history. He blurs the distinction between facts and imagination, making us regard Shreve's and Quentin's conjectures as facts in several ways. The conversation between father and son, and the two brothers, which is an imagination constructed through the clues Mr Compson has offered, becomes a fact willingly accepted by the readers as well as Shreve and Quentin. The people in the past, present, and future may be very much unlikely to agree on the same event, because the gap in temporality will keep widening our perceptions. Faulkner demonstrates the nature of history in such a way that we can compare our understanding of the Sutpens' history in the earlier and later part of the novel through repetitions.

• Korean Institute of Interior Design Journal
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• no.21
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• pp.165-172
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• 1999

For the useful method capable of modern expression on traditional residence architecture, a study was performed on the methodological establishment and possibility of typological method could be examinated to interior design process by typological method. First of all, through the establishment verbal of our Korean traditional architecture and further investigation of environmental and cultural idealogical facts, it could be extracted from natural instinct, duality, continuance, flexibility and transitiov. In second process, based on these results, it could be framed and described the individual typological language and, for the sake of drawing for visual and spatial typology, it was made by sketch in terms and view of possibile guidance of prototype, transforming and application method. from these results of investigated sketches, it cold be used for criteria of application method as the parts of visual and spatial typological elements to have an applicable expression of it/s traditionality. Based on above facts, for the subjects of spatial system, form & shape system, circulation system, order system, decoration system, color & material system in interior design fields, we cold propose the practical possibility through the consideration of application method for built-in meaning that could be adaptable for the interior design practices. These facts were extracted from the based on visual & spatial typology, as above mentiov. Also, through preparing and suggesting the criteria of evaluation and measurement of design quality , we could propose the applicable methodology for further & basically Korean traditional embodiment.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.315-322
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• 2009

Penetration and installation of a new dynamic technology known as Flexible AC Transmission Systems (FACTS) in a practical and dynamic network requires and force expert engineer to develop robust and flexible strategy for planning and control. Unified Power Flow Controller (UPFC) is one of the recent and effective FACTS devices designed for multi control operation to enhance the power system security. This paper presents a dynamic strategy based on Particle Swarm Optimization (PSO) for optimal parameters setting of UPFC to enhance the system loadability. Firstly, we perform a multi power flow analysis with load incrementation to construct a global database to determine the initial efficient bounds associated to active power and reactive power target vector. Secondly a PSO technique applied to search the new parameters setting of the UPFC within the initial new active power and reactive power target bounds. The proposed approach is implemented with Matlab program and verified with IEEE 30-Bus test network. The results show that the proposed approach can converge to the near optimum solution with accuracy, and confirm that flexible multi-control of this device coordinated with efficient location enhance the system security of power system by eliminating the overloaded lines and the bus voltage violation.