• Journal of information and communication convergence engineering
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• 제6권2호
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• pp.182-186
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• 2008

RFID systems generate huge amount of data quickly. The data are associated with the locations and the timestamps and the containment relationships. It is requires to assure efficient queries and updates for product tracking and monitoring. We propose a clustering technique for fast query processing. Our study presents the state charts of temporal event flow and proposes the dependence trees with data association and uses them to cluster the linked events. Our experimental evaluation show the power of proposing clustering technique based on dependence tree.

• 한국화재소방학회논문지
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• 제14권1호
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• pp.1-7
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• 2000

절연재료의 내부에서 부분방전이 발생하면 국부파괴와 완전절연파괴의 원인이 된다. 부분방전으로 생기는 트리잉은 절연재료를 열화시키고 절연 수명을 단축시키는 중요한 원인이 된다. 따라서 절연파괴의 예측과 절연재료의 수명을 진단할 수 있는 방법에 대한 연구는 매우 중요하다. 고전압 하에서 일어나는 트리잉 현상에 대해서 저밀도 폴리에틸렌의 트리잉 개시 전압과 그 진전 과정을 진성파괴의 견해에서 고찰하였다. 이러한 관점에서 본 연구는 고전압하에서 일어나는 트리잉현상에 대해서 저밀도폴리에틸렌에서 트리형상의 전계의존성에 관하여 고찰하였다. 결과로서 트리의 성장을 그 내부가 각각 유전체 혹은 도체라고 가정했을 때의 중간적인 특성을 갖는다는 추리하에 이론적으로 검토한 결과, 실험결과와도 잘 일치됨을 알 수 있었다.

• 한국지능시스템학회논문지
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• 제7권1호
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• pp.5-15
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• 1997

This paper mentions a fault tree analysis using not probability but natural language and fuzzy theory, Reliability estimate of each basic event and dependence level estimate among subsystems are expressed by linguistic terms. Analysis results are also expressed by natural language. The meaning of linguistic terms is expressed by a fuzzy set. In the presented analysis approach parametrized operations of fuzzy sets are considered so that analyst's subjectivity can be introduced into the analysis. This paper gives the Chernobyl accident as an example of the fuzzy fault tree analysis using linguistic terms.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.59-62
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• 1999

Inception and propagation of electrical tree and properties of Partial discharge(PD) pulses accompanying with tree as a function of needle tip radius in low density polyethylene were discussed. To study on these characteristics in different tip radius, we used specimens with needle-plane electrode system made of LDPE, observed inception and propagation of electrical tree by optical microscope with computer and investigated the characteristics of the phase resolved PD pulses accompanying with propagation of electrical tree. The PD quantities detected and analysed were PD magnitude, mean phase angle, average discharge, and the statistical characteristics of the PD pulses. As the tip radius ${\gamma}$ increases, tree inception stress E$\sub$i/ converges to constance value. This result suggests that tree inception stress E$\sub$i/ increases due to stress relaxation when the tip radius is small. Branch-type electrical tree was formed When E$\sub$i/ is 640-750[kV/mm]. bush-type electrical tree when E$\sub$i/ is 370∼400[kV/mm], branch-like electrical tree when E$\sub$i/ is 370-400[kV/mm].

• 대한전기학회논문지
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• 제41권2호
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• pp.178-184
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• 1992

This study treats the improvement of the dielectric strength of polymer by eliminating the air in it and dissolving electronegative gases. As experimental material, unsaturated polyester resin was used and the specimen was made by dissolving NS12T. SFS16T abd CCIS12TFS12T gases which have strong electron affinity. And also the electrical properties (tree growth and breakdown characteristics) of them were tested and discussed. The results are as follows. When the specimen dissolved with electronegative gas compared with one with air` 1) The tree breakdown voltage of the former is higher than that of the latter. 2) The tree growth of the former is slower than that of the latter. 3) The temperature dependence of the former is smaller than that of the latter. 4) The breakdown voltage of the specimen dissolved with electronegative gas is much higher than that dissolved with air.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.212-214
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• 1996

The growth of tree is affected by voltage, frequency, temperature, mechanical stress, etc.. This paper describes the effect of applied voltage on the growth of tree in DGEBA/MDA/GN(10 phr) system. As applied voltage increased, the time to breakdown of the system reduced. As applied time increased, the tree length of X-axis increased with sigmoid shape, however, the tree length of Y-axis increased sharply at the initial step and then were nearly constant. The phenomena of tree were complicated more and more, as applied time increased.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.425-428
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• 1996

Treeing deterioration which is one of the main cause of breakdown in insulating materials is affected by temperature, applied voltage and frequency. In this study, GN was introduced to improve impact strength of DGEBA/MDA system and the temperature dependence of AC treeing deterioration in this system was investigated. Dielectric breakdown strength decreased with the increment of temperature. As temperature increased, the growth rate of tree Increased.

• 한국융합학회논문지
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• 제11권5호
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• pp.97-105
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• 2020

본 연구는 어머니가 지각한 유아의 스마트폰 과의존에 대한 주요 예측요인을 밝혀내고 교육 및 실천현장에 유용한 기초자료를 제공하는 것을 목적으로 수행되었다. 조사대상은 경상북도에 거주하는 만4세-7세 유아의 주양육자인 어머니로 총 410부가 분석에 활용되었다. 데이터마이닝 의사결정나무 분석을 위해 SPSS 23.0 프로그램을 활용하였고, 그 결과는 다음과 같다. 첫째, 전체 유아를 대상으로 보았을 때, 스마트폰 과의존을 가장 중요하게 예측하는 변인은 아버지의 여가활동 양육참여로 나타났다. 둘째, 성별에 따른 차이를 분석한 결과, 남아는 아버지의 여가활동참여가 스마트폰 과의존에 가장 관계가 높은 것으로 나타났다. 하지만, 아버지의 여가활동 참여가 높더라도, 어머니의 과보호와 허용적 태도가 높은 경우 스마트폰 과의존은 다시 증가하였다. 여아의 경우, 스마트폰 과의존에 가장 높은 영향을 미치는 변인은 어머니의 양육태도 중 온정과 격려로 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2051-2053
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• 1999

In this work, PD patterns and electrical trees are observed by use of the XLPE cable insulation. and the tree initiation voltage related to the contamination are also measured in order to calculate the electric stress necessary for the design of cable insulation. Throughout these works, correlation between the PD pattern and the shape of electrical tree has been observed that there may exist three distinct pattern of PD dependence on the stage of tree propagation, Such correlation could bring a basic information in connection with the partial discharge of cable system. It was also found that the electrical stress necessary for the initiation of electrical tree was measured to the 290kV/mm for the 154kV XLPE cables manufactured in KOREA.

• Transactions on Electrical and Electronic Materials
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• 제3권3호
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• pp.34-38
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• 2002

In this paper, efficiency estimation of toxicity fee fire resistance cable experiments was measured smoke density of toxicity free fire resistance polyolefin insulation material and electric field dependence of tree shape in low density polyethylene (LDPE). One of the most serious causes of failure in high-voltage cables, can be an electrical discharge across an internal gab or void in the insulating material. Treeing due to partial discharge is one of the main causes of breakdown in the insulating materials and reduction of the insulation life. Therefore the necessity for establishing a method to diagnose the aging of insulation materials and to predict the breakdown of insulation and research of the fire resistance character has become important. First, we have studied on electric field dependence of tree shape in LDPE about treeing phenomena occurring on the high electrical field. Second, the measurement method is the attenuation quantity of irradiation by smoke accumulating with in a closed chamber due to non-flaming heat decomposition and flaming combustion. A main cause of fire-growth and generating toxic gas when, it bums, should be dealt with great care in life. safety design. The fire gases were occurred carbon monoxide and decomposition than in polyolefin due to incomplete combustion of PVC, which has high content of carbon in chemical compound.