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Ko, Young-Hun;Kim, Chul-Hwan;Ahn, Sang-Pil
- KIEE International Transactions on Power Engineering
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- v.3A no.3
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- pp.130-138
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- 2003
This paper presents a discrete wavelet transform approach for determining the beginning and end times of voltage sags. Firstly, investigations in the use of some typical mother wavelets, namely Daubechies, Symlets, Coiflets and Biorthogonal are carried out and the most appropriate mother wavelet is selected. The proposed technique is based on utilizing the maximum value of Dl (at scale 1) coefficients in multiresolution analysis (MRA) based on the discrete wavelet transform. The results are compared with other methods for determining voltage sag duration, such as the Root Mean Square (RMS) voltage and Short Time Fourier Transform (STFT) methods. It is shown that the voltage sag detection technique based on the wavelet transform is a satisfactory and reliable method for detecting voltage sags in power quality disturbance analysis.
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하형호;강성진
- Journal of the military operations research society of Korea
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- v.29 no.2
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- pp.81-99
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- 2003
This paper propose a method determining life cycle for military vehicle using availability analysis. Many studies determining life cycle for military equipments have been done recently However, those studies focused on economic life such as average system cost method, equivalent annual cost method and cumulative operations cost method. In many case, those results are not appropriate in deciding replacement in the field situation, we consider an effective life cycle method using availability concept. In order to determine an equipment life cycle. Two kinds of availability is considered. One is equipment yearly availability, the other is operational availability with operating distance per year. The life cycle is determined by achieving unit target availability level. The result using this concept for K511 military vehicle life cycle is about 19 years, which is longer than previous studies.
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Seung Ho Hong
- Journal of the Korean Institute of Telematics and Electronics B
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- v.30B no.1
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- pp.18-28
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- 1993
Processes in the real-time distributed control systems share a network medium to exchange their data. Performance of feedback control loops in the real-time distributed control systems is subject to the network-induced delays from sensor to controller, and from controller to actuator. The network-induced delays are directly dependent upon the data sampling times of control components which share a network medium. In this study, an algorithm of determining data sampling times is developed using the "window concept". where the sampling datafrom the control components dynamically share a limited number of windows. The scheduling algorithm is validated through the aimulation experiments.
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김상규;류지협;구호본;정하익;윤수호
- Proceedings of the Korean Geotechical Society Conference
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- 1999.03a
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- pp.269-276
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- 1999
The program ESRAS Ver 0.5 that can assess the risk of slopes by means of fuzzy inference is developed in this paper. The results of assessment involve the degree of stability of slopes, the possible travel distance of the soil mass being failed, and anticipated loss of life and properties. With this program, vulnerable slopes can be managed most effectively and the fuzzy inference is used to express quantitatively the judgement of an expert and the uncertainty of slope stability. The fuzzy rule base is composed of an evaluation list for slope stability together with the experience of an expert. This program has been examined for 88 slopes which have been failed or shown a possibility of failure. With this examination, the standards to assess the stability of slopes can be presented and it is proven that this is particularly useful in determining the priority of investment for remedial works of slopes.
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