• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.9
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• pp.591-599
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• 1988

After the short-term dynamics due to the major disturbance are over, the power system may lead to viability crisis state wherein there is possibility of cascading damage. This paper presents an emergency control algorithm to alleviate the obstacles of system frequency or bus voltage during the viability crisis state. The algorithm considers the effects of controlling reactive power sources for load shedding and generation reallocation in order to alleviate the obstacles. The problem is decomposed into a subproblem I and a subproblem II. The former minimizes system frequency deviation from nominal value and the latter voltage violation of load buses. The optimization problem is solved by a reduced gradient technique which can handle a great number of inequality constraints more easily. It has been verified that the use of the proposed algorithm for IEEE 14 bus system alleviates the obstacles efficiently during the viability crisis.

• Journal of Communications and Networks
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• v.15 no.6
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• pp.606-613
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• 2013

This paper proposes a complete solution of a contention-based medium access control in wireless local networks to provide station level quality of service guarantees in both downstream and upstream directions. The solution, based on the mature distributed coordination function protocol, includes a new fixed contention window backoff scheme, a tuning procedure to derive the optimal parameters, a super mode to mitigate the downstream bottleneck at the access point, and a simple admission control algorithm. The proposed system guarantees that the probability of the delay bound violation is below a predefined threshold. In addition, high channel utilization can be achieved at the same time. The numerical results show that the system has advantages over the traditional binary exponential backoff scheme, including efficiency and easy configuration.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.8
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• pp.140-149
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• 2011

This paper deals with the impact analysis of the impedance change of 345/154[kV] power transformers on the KEPCO system's overall performance. Through the steady-state and dynamic analysis of power system, the maximum available impedance of power transformers were determined. Checking violation of short-circuit current ratings and transformer overload, parallel operation of power transformers, calculation of voltage variation ratio according to the impedance changes of power transformers are included in the steady-state analysis. In addition, transient and voltage stability analysis are also performed in the study. Available magnitudes to be able to change the impedance of the transformers in KEPCO system are finally determined in the paper.

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.210-223
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• 2020

Since constrained optimization algorithms are easy to fall into local optimum and their ability of searching are weak, an improved symbiotic organisms search algorithm with mixed strategy based on adaptive ε constrained (ε_SOSMS) is proposed in this paper. Firstly, an adaptive ε constrained method is presented to balance the relationship between the constrained violation degrees and fitness. Secondly, the evolutionary strategies of symbiotic organisms search algorithm are improved as follows. Selecting different best individuals according to the proportion of feasible individuals and infeasible individuals to make evolutionary strategy more suitable for solving constrained optimization problems, and the individual comparison criteria is replaced with population selection strategy, which can better enhance the diversity of population. Finally, numerical experiments on 13 benchmark functions show that not only is ε_SOSMS able to converge to the global optimal solution, but also it has better robustness.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.5
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• pp.86-93
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• 2015

Recently, ESS became efficient device to stabilize electric power supply system with the development SG related technology. In fact. there are some constraints to supply ESS, because of the high cost and required space, but rapid technology development for ESS will make it more useful soon. So, through this paper, we analyzed the benefit and demand effect when the battery is applied the building based on the measured energy consumption. After that, we got the conclusion that there is a volume limit in ESS application, in a benefit view point. And we realized that there is a demand violation, and the Cost-based BEMS is the best solution to enhance the effect of ESS application.

• Proceedings of the KSPS conference
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• 2003.05a
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• pp.159-162
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• 2003

In this paper I investigate the intervening consonants constraint in umlaut in Korean. It is generally known that if a palatalized consonant, i.e. s/ㅅ/ or $t{\int}/ㅈ/$ etc, intervenes in an umlaut environment, the expected umlaut process is blocked. But there are not a few words which are thought to have undergone umlaut diachronically: wensu $( If we assume that these words were formed as a result of umlaut, we must explain the reason of the violation of the intervening consonants constraint. On the other hand if we assume that these words were formed as a result of other phonological processes, we must explain these words by ad hoc rules respectively. In this paper I argue that these words including others have undergone the umlaut process by offering some historical and dialectal evidence.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.4
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• pp.21-25
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• 2005

In the dynamic analysis of a mechanism, if one or more of the components are flexible, then the simulation will not be accurate because of the violation of the rigid body assumption. Mode shapes are used to represent the dynamic behavior of an elastic structure. A modal synthesis method which uses a combination of normal modes, constraint modes, and attachment modes, was used to represent effectively the elastic deformation of a flexible multibody. Since the combination of these modes should be different for each type of connecting part, the modal synthesis method was studied for the various types of interconnecting joints. In addition, the analysis procedure for the flexible body was explained. A satellite system with flexible solar panels was chosen as an example to show the effectiveness of the proposed method.

• Language and Information
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• v.6 no.2
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• pp.171-185
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• 2002

I claim that the asymmetry of locality effects in wh-questions involving Complex Noun Phrase Island in Korean follows from the proposal for the asymmetric mode of scope taking between way (why) and the other wh-words in Korean as laid out in Choi (2002). 1 will show that the present proposal is superio. to the LF pied-piping approach in Nishigauchi (1990) and WH-structure pied-piping in von Stechow(1996) in that it does not have the fatal problem of wrong semantics in Nishigauchi and Subjacency violation problem in von Stechow. The crossed reading in examples involving Wh-island has an interesting implication for the mechanism of unselective binding, suggesting that Heim's (1982) quantifier indexing mechanism, which requires the local unselective binding of the indefinite by the unselective binder, may be too strong.

• Journal of KIISE:Software and Applications
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• v.27 no.8
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• pp.902-911
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• 2000

A language module is the collection of language constructs whose concepts and operations are closely related. This paper demonstrates how to use action semantics to define and extend language modules. We first define a language module for an expression language core, and then language modules for bindings, block structures, parameters, and higher-order expressions. Finally, we show that the language modules can be combined, if there is no violation of uniformity and orthogonality, to become a more complex language module.

• Journal of Information Technology Services
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• v.2 no.1
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• pp.25-34
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• 2003

Spam mail is one of the side effect of the development and improvement of the internet that restrains the privacy of the individual on line. However indiscriminate application of Spam mail blocking can also cause significant violation on freedom of doing business to the fluent commercial transactions on line. Therefore this research looks at the exact understanding of the concept of Spam mail and inquiry on Its issues. Also it looks at the case studies of its institutional solutions in USA and Europe as well as the advantage and disadvantage of the case studies on its technical solution. Finally, the research inquires into overall prevention of Spam mail, which considers both technical and institutional soiution. With this research, limitations of current Spam mail prevention system and technology are pointed out and more effective course of overall Spam mail prevention solution is studied.