• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1871-1873
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• 2000

There are many electrical accidents between bare wire and line post insulator which is degraded by long time using, causing leakage current on the surface of insulator. In this paper it is presented that the 22.9 Kv-y distribution lines are protected by binding cover which is needed from fog or rainy moisture, surges occurring by switching or lightening pulse. It is analyzed to investigate the unbalanced transfer characteristics and reflection coefficient by using binding cover and non-cover. It was tested the radio interference voltage in the test room and electric field strength by calculation between binding cover and non-cover. In the factory the leakage current causing on the surface of insulator was tested in the state of light load and heavy load.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.9-10
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• 2006

가공배전선로는 태풍 내습시 전주 및 전선에 작용하는 풍압에 대하여 견딜 수 있도록 설계되어져야 한다. 따라서 본 연구에서는 가공배전선로의 설계시 사용되는 전주에 가해지는 풍압에 의한 굽힘모멘트 및 굴곡개소의 합성모멘트 계산시 사용하는 기존 계산식의 문제점을 분석하고 현장에서 쉽게 적용 가능한 새로운 계산식을 유도하였다. 새로운 계산식을 이용하여 설계자들이 가공배전선로의 지지물 및 지선강도를 검토할 수 있게 됨으로써 태풍과 같은 재해시에도 안전한 설비를 시설할 수 있게 되었다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.120-126
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• 1999

;The consicErations for reminder life of transmission line is gradually higher. It is requisite for investigation of ACSR's life to test tensile load of ACSR as a fundamental data. It is vary important to analysis correlations between results of tensile load testing and elasped years. Estimation of ACSR's life can be obtained by statistics processing using mechanical experirrental results. It is a general method to use regression analysis as a statistics processing technique. In this paper, we did experiment on tensile strength of ACSR by using a new and old ACSR as sample experirrental materials. The limit of life estimation is decided by basic line using twenty percentage reduction of rate tensile strength. This basic line is like to results of Canada Ontario Hydro-research. There are $95[\textrm{mm}^2]$, $97[\textrm{mm}^2]$, $120[\textrm{mm}^2]$, $240[\textrm{mm}^2]$ ACSRs which are experimented on this study. 1be life estimation of these ACSR is presented by table 1 to be obtained through the linear regression and nonlinear regression analysis. SPSS and statistics toolbox of matlab is used for analysis.lysis.

• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.237-247
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• 2020

The purpose of this study is to analyze whether design rainfall and hyetograph, which are the main elements of design rainfall, can properly reflect the those of observed rainfalls through inundated rainfall events. The target areas were selected at seven large cities with high damages regarding to the flooding. Comparative analysis between probability and observed rainfall shows that 57% of the cases, in which rainfall amount through the IDF curve is estimated lower than the observed rainfall, do not properly reflect the observed rainfalls. In particular, this trend is exacerbated by the cases in low return period and the rain type of typhoon or frontal rain. The comparative results of rainfall intensity formula showed that the Talbot and Japanese formula were stable in the short- and long-term return periods, respectively. The comparison of hyetograph results also showed that the Mononobe method properly reflects the maximum rainfall intensity and the Huff method properly reflects the shape of rainfall pattern.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.3 s.22
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• pp.57-68
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• 2006

The objective of this study is to analyze the temporal pattern characteristic of short-duration rainfall defined as a rainfall durations of 6 hours or less by the Huff's 4th quartile distribution. To analyze the temporal pattern characteristic of short-duration rainfall, the rainfall data are classified by rainfall duration and rainfall type(Changma, Typhoon, Severe rain storm, Frontal storm) and change of rainfall segment. Also, the results of this study compared with result of research work of Korea Institute of Construction Technology(1989) and Ministry of Construction & Transportation(2000). The conclusions of this study are as follows; (1) Short-duration rainfall with duration of 6 hours or less is found to be most prevalent frist-quartile storms. (2) In the case of rainfall type, Changma and Severe rain storms and Frontal storm is found second-quartile storms, and Typhoon is found third-quartile storms. (3) In the result by change of sixth segment storms, the type of temporal pattern of rainfall is found to be most prevalent two sixth parts, (4) Comparative analysis of the results shows that shapes of the dimensionless cumulative curves and values are different from those of existing researches.

• Journal of the Korean association of regional geographers
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• v.20 no.4
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• pp.393-408
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• 2014

In this study, the spatio-temporal characteristics of summer extreme precipitation events in the Republic of Korea are examined based on the daily precipitation data observed at approximately 360 sites of both Automatic Weather Station (AWS) and Automated Synoptic Observation System (ASOS) networks by the Korea Meteorological Administration for the recent decade(2002~2011). During the summer Changma period(late June~mid July), both the frequency of extreme precipitation events exceeding 80mm of daily precipitation and their decadal maximum values are greatest at most of weather stations. In contrast, during the Changma pause period (late July~early August), these patterns are observed only in the northern regions of Geyeonggi province and western Kangwon province as such patterns are detected around Mt. Sobaek and Mt. Halla as well as in the southern regions of Geyeonggi province and western Kangwon province during the late Changma period (mid August~early September) due to north-south oscillation of the Changma front. Investigation of their regional patterns confirms that not only migration of the Changma front but also topological components in response to the advection of moistures such as elevation and aspect of major mountain ridges are detrimental to spatio-temporal patterns of extreme precipitation events. These results indicate that each local administration needs differentiated strategies to mitigate the potential damages by extreme precipitation events due to the spatiotemporal heterogeneity of their frequency and intensity during each Changma period.

• Elastomers and Composites
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• v.39 no.2
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• pp.131-141
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• 2004

The recycling of waste XLPE(crosslinked polyethylene), which is a major source of scraps from high voltage power transmission cables, has been discussed. The waste XLPE scraps were ground into fine powder with various sizes from less than $100{\mu}m$ up to about $1000{\mu}m$ using two types of tailor-made pulverizers. The compounds were prepared in a modular intermeshing co-rotating twin screw extruder at various conditions such as different compositions, types and powder sizes of waste XLPE, screw configurations and various polymer matrices (LDPE, HDPE, PP, PS). The mechanical and rheological properties and the fracture surface or the compounds were investigated. It was found that an improved impact strength was obtained from the compound with white XLPE powder pulverized from the scraps without outer/inner semi-conductive layers. Generally, the impact strength increases with the content of XLPE but decreases with the size of XLPE. Especially for LDPE, the extrusion was possible up to 80 wt% loading of XLPE. Also, the impact strength increases with the number of kneading disc blocks in the given screw configurations. The melt viscosity of the compounds increases with increasing XLPE loading. However, the higher shear thinning behavior of the compounds at common shear rates implies proper processibility of the compounds. In addition, the impact strength for other polymer matrices used increases with XLPE and it is noticeable that the impact strength of PS/XLPE (80/20 wt%) compound was improved twice that of pure PS.

• The Journal of Engineering Geology
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• v.25 no.3
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• pp.377-385
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• 2015

We constructed a model test apparatus to evaluate the dependence of the saturation velocity (V_s) in soils on rainfall intensity (I_R). The apparatus comprises a soil box, a rainfall simulator, and measuring sensors. The model grounds (60 cm × 50 cm × 15 cm) were formed by Joomunjin standard sand with a relative density of 75%. The rainfall simulator can control the rainfall intensity to reenact the actual rainfall in a soil box. Time Domain Reflectometer (TDR) sensors and tensiometers were installed in the soils to measure changes in the volumetric water content and matric suction due to rainfall infiltration. During the tests, the soil saturation was determined by raising the groundwater table, which was formed at the bottom of the soil box. [Please check that the correct meaning has been maintained.] The wetting front did not form at the ground surface during rainfall because the soil particles were uniform and the coefficient of permeability was relatively high. Our results show that the suction stress of the soils decreased with increasing volumetric water content, and this effect was most pronounced for volumetric water contents of 20%-30%. Based on a regression analysis of the relationship between rainfall intensity and the average saturation velocity, we suggest the following equation for estimating the saturation velocity in soils: V_savg (cm/sec) = 0.068I_R (mm/hr).

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.555-557
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• 2000

원자력 발전소에서 사용되어지는 케이블은 전원 및 제어신호를 안정하게 전달하는 역할을 하며, 비상상태 발생시에는 원자로를 안전하게 shut-down시키는 통로 역할을 하므로 매우 중요하다. 케이블 상태 감시시 절연 및 피복재료는 종류 및 배합내용이 다양하기 때문에 종래의 자료로부터 전선과 케이블의 열화 또는 수명을 추정하기가 극히 어려우며 방사선에 노출이 되는 케이블의 경우 노화현상의 진행이 빠르고 방사선 열화로 수명이 단축되므로 국내 실정을 감안한 독자적인 검증방법 도출, 규제기술 기반 구축 필요 및 규제의 합리화와 효율화 필요성이 대두되고 있다. 기존에 사용해온 케이블 진단 방법에는 절연 파괴 강도 측정을 통한 노화진단, 산화 방지능력 측정을 통한 노화진단, 자켓 및 절연체의 판단, 연신율에 의한 노화진단, 케이블 Indenter에 의한 노화진단, 온도 및 방사선 등의 특정상태에 대한 평가, 유사한 환경조건에 대한 주기적 검토 등이 있다. 기존의 국내외 케이블 상태 감시방법을 조사 연구하므로서 케이블 열화에 대비한 수명관리 규제 기술 및 상태감시 (Condition Monitoring : CM) 기술의 평가 기준을 결정 하고자 한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.1
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• pp.37-42
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• 2013

Double pipe system in which PB pipe is inserted in CD pipe buried in the concrete slab is widely used for cold and hot water supplies in apartment housings. The system, however becomes complicated and the overlaying pipes in the concrete slab weaken the compressive strength of the slab. Also, insufficient insulation increases energy loss. In this work, the problems of the double pipe system are studied and plans A, B, and C are suggested for improvement. In terms of compressive strength of the concrete slab, plan A(total pipe length 73 m) was the weakest and plan B(2 m) was the strongest. Energy loss of plan A was the largest with 558.9 W and plan B was the lowest with 220.7 W. However, considering the combined effect of strength and heat loss, plan C becomes the best choice, which retains the advantage of the double pipe system.