• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.5
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• pp.453-456
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• 2016

The major causes of electrical fire in low-voltage distribution lines are classified into short-circuit fault, overload fault, electric leakage, and electric contact failure. The special principal factor of the fire is electric arc or spark accompanied with such electric faults. This paper studies the development of an electric fire prevention system with detection and alarm of that in case of parallel arc fault occurrence in low-voltage distribution lines. The proposed system is designed on algorithm sensing the instantaneous voltage drop of line voltage at arc fault occurrence. The proposed detector has characteristics of high-speed operation responsibility and superior system reliability from composition using a large number of semiconductor devices. A new sensing control method that shows the detection of parallel arc fault is sensed to ripple voltage drop through a diode bridge full-wave rectifier at electrical accident occurrence. Some experimental tests of the proposed system also confirm the practicality and validity of the analytical results.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.152-155
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• 2002

Epicoccosorus nematosporus was detected in all 22 counties surveyed, but the frequency of occurrence of fingerprint stem blight disease (FSBD) on Eleocharis kuroguwai caused by the fungus varied with fields and regions. The disease occurred more frequently in mountain areas than in plain areas. E. nematosporus was detected in less than 20% of plain areas such as Cimjae and Milyang, whereas, it occurred in 40-60% of mountain areas such as Sangiu and Jangsoo. In Milyang, mean temperature in July to August 1993 ranged from 17 to $27^{\circ}C$ with 14.3 h of dew period. Meanwhile, in the mountain area such as Sangiu, Gyeongbook, temperature ranged from 17 to $24^{\circ}C$ with 16.1 h of dew period. Plant mortality was 61% in Milyang and 82% in Sangju. Underground tuber formation was highly suppressed at 16 and 33 tubers per plot in Sangju and Milyang, respectively. In 1992 and 1995, plants infected ranged from 40 to 78% in July to September. This sharply decreased to an average of 15% in 1999.

• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.15-21
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• 2019

In order to secure the safety of various machinery, it is very important to develop a technique for accurately and quickly measuring the cracks generated in the mechanical equipment and evaluating the mechanical characteristics. The evaluation of the mechanical properties is accompanied by an appropriate strain measurement according to the material and crack occurrence of the target structure. Especially, when micro cracks are generated, the evaluation method is very important. Digital image correlation is an optical full field displacement measuring method which is using currently with speckles in the interested area. However the evaluation method and conditions of image distributions have to be considered carefully to measure the crack occurrence because the images of the speckle patterns affect the quality of displacement results. In this study, the speckle pattern density is characterized to improve the accuracy of the measurement method. And also the micro crack initiation is detected by the measured displacement in the adopted speckle pattern distribution. It is shown that the proposed method is useful to determine the density pattern distribution for the accurate measurement and crack detection.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4B
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• pp.399-404
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• 2006

Kweon et al. (2004) proposed the calculation method of Expected Overtopping Probability (EOP) that considers the occurrence frequency distribution of real sea tide. The method was applied for the comparison of the EOP of Mukho and Busan sea. They showed that the tide occurrence frequency had a great effect on the EOP and the value becomes smaller as the standard deviation of the frequency comes bigger. The present study following Kweon et al.'s method estimates the EOP characteristic of the crest elevation located on East, South, and West sea. The study shows that the EOP becomes smaller following East, South, West sea in order.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.127-134
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• 2006

Based on a weakly non-Gaussian theory the occurrence probability of freak waves is formulated in terms of the number of waves in a time series and the surface elevation kurtosis. Finite kurtosis gives rise to a significant enhancement of freak wave generation in comparison with the linear narrow banded wave theory. For fixed number of waves, the estimated amplification ratio of freak wave occurrence due to the deviation from the Gaussian theory is 50% - 300%. The results of the theory are compared with laboratory and field data.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.809-812
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• 2006

This article shows the study on the arresting sound occurrence due to the interaction of the centrifugal Fan and bellmouth suction flow with bellmouth height as variable. It has accomplished to measure of inlet noise and also to analysis suction pressure distribution through experiment and also using CFD. The main cause of sound occurrence was judged with the effect due to static pressure change of bellmouth surface.

• Communications for Statistical Applications and Methods
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• v.13 no.2
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• pp.369-378
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• 2006

This Study focuses on the binary forecast of occurrence of heavy snow in Honam area based on the MOS(model output statistic) method. For our study daily amount of snow cover at 17 stations during the cold season (November to March) in 2001 to 2005 and Corresponding 45 RDAPS outputs are used. Logistic regression model and neural networks are applied to predict the probability of occurrence of Heavy snow. Based on the distribution of estimated probabilities, optimal thresholds are determined via true shill score. According to the results of comparison the logistic regression model is recommended.

• The Korean Journal of Ecology
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• v.14 no.4
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• pp.457-467
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• 1991

Occurrence and distribution of the celluar slime molds in relation to the coastal plant communities of svven islands near inch'on wereinvestigated. as a results, total seven species were isolated from the soils of the coastal plant communities. These are dictyostelium mucoroides, polysphodylium pallidum, dictystelium polycephalum. d. mucoroides was the most commonly found in the coastal plant communities investigated, and was dominant pecularly in the coastal mixed forests, the coastal broad-leaved forests and salt marshes. In the coastal coniferous forest and the coastal dune sand plants, hoeever, p. violaceum was the dominant species. species diversity was relatively was relatively high in the coastal coniferous ferests and the coastal mixed forests. However, agerage number of species isolated from all plant communities was very low,2.8.

• Environmental Engineering Research
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• v.20 no.3
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• pp.230-236
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• 2015

26 multi-regional water treatment plants (WTPs) were investigated, to determine the characteristics of manganese (Mn) concentration and removal in Korea. Mn concentrations of raw water in most WTPs were higher than the drinking water standard (i.e., 0.05 mg/L); thus, proper removal of Mn at the WTPs is needed. Mn concentration was generally higher in lakes than rivers due to seasonal lake turnovers. The Mn concentrations of treated water at 26 WTPs in 2012 were less than 0.05 mg/L, due to strict law enforcement and water treatment processes optimization. However, before 2010, those concentrations were more than 0.05 mg/L, which could have led to an accumulation of Mn oxides in the distribution system. This could be one of the main reasons for black water occurrence. Therefore, regular monitoring of Mn concentration in the distribution system, flushing, and proper Mn removal at WTPs are needed, to supply clean and palatable tap water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.603-606
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• 2004

Aspects of PD occurrence from PD sources are different with their physical and structural appearances which cause the variation of electric field distributions of them. This paper have investigated electric field distributions of some kinds of electrode structure by FEM applied analysis program. Numeric analysis is a good method to investigate Ihe electric and magnetic field distribution of partial discharge source. The analysis results were confirmed by real PD occurring situation in the laboratory.