• Title/Summary/Keyword: negative polarity

Search Result 207, Processing Time 0.037 seconds

Characteristics of lightning impulse preliminary breakdown discharge under non-uniform electric field in $SF_6/CO_2$ mixtures (불평등전장에서 $SF_6/CO_2$ 혼합기체의 뇌임펄스 전구방전특성)

  • Lee, B.H.;Oh, S.K.;Baek, Y.H.;Ahn, C.H.;Jeon, D.K.
    • Proceedings of the KIEE Conference
    • /
    • 2005.07c
    • /
    • pp.2140-2142
    • /
    • 2005
  • This paper presents the experimental results on the preliminary breakdown characteristics under a highly non-uniform electric field in $SF_6/CO_2$ gas mixtures. The impulse preliminary breakdown developments are investigated by the measurements of corona current and light emission images. As a result, the preliminary breakdown development mechanisms for both positive and negative polarities are same. The first streamer corona is initiated at the tip of needle electrode, and the leaders develop with a stepwise propagation and bridge the test gap. The pause time of leader pulses in the positive polarity is significantly shorter than that in the negative polarity. Also, the time interval between the first streamer corona onset and breakdown in the negative polarity was much longer than that in the positive polarity The discharge channel paths in the positive polarity were zigzag. On the other hands, the leader channel in the negative polarity was thicker than that in the positive polarity.

  • PDF

Study on IPT Characteristics of LSR / Nano Silica Composites for HVDC (HVDC용 LSR/Nano Silica Composites의 IPT특성 연구)

  • Park, Jae-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.68 no.1
    • /
    • pp.61-68
    • /
    • 2019
  • Only the power is converted from AC to DC, in accordance with IEC 60587 based test method, in order to develop the LSR(Liquid Silicone Rubber) insulator material for HVDC, the experiment of Inclined Plate Tracking and Erosion Resistance was conducted. A contaminant (2.5 mS/cm: ammonium chloride) was applied at a rate of 0.3 ml/min and a voltage of ${\pm}3.5kV$, and was evaluated on the basis of 60 mA/2s. The samples were prepared by dispersing LSR/Nano silica_25wt% Composites in LSR. The erosion phenomena of surface discharge and tracking due to DC polarity and negative polarity were measured by image, leakage current maximum and thermal camera. The thermal imaging camera measured the surface temperature generated by the joule heat of the leakage current due to the drying discharge and the conductive current. After the measurement, the tracking and erosion mechanisms were evaluated for erosion weight, erosion depth and erosion length. Positive and negative polarity of LSR/Nano Silica_25wt% composite Tracking and erosion results show that positive polarity is more severe than negative polarity.

Determination of Charged Particles and their Polarity by Temperature Gradient Thermally Stimulated Measurement (온도구배 열자격 측정에 의한 하전입자의 구별 및 극성 판정)

  • 권영수;강도열;국상훈
    • The Transactions of the Korean Institute of Electrical Engineers
    • /
    • v.38 no.8
    • /
    • pp.600-609
    • /
    • 1989
  • A thermally stimulated measurement using a temperature gradient has been applied to the study of charged particles and their polarity n polymers. From the experimental results on a cross-linked polyethylene (XLPE) film is found that the TSC peaks of the trapped carriers in C peak are due to the negative polarity which is electron and the ionic carriers having negative polarity show D peak.

  • PDF

An Analysis of Syntactic and Semantic Relations between Negative Polarity Items and Negatives in Korean. (결합범주문법을 이용한 한국어 부정극어와 부정어의 통사 및 의미적 관계 분석)

  • 김정재;박정철
    • Language and Information
    • /
    • v.8 no.1
    • /
    • pp.53-76
    • /
    • 2004
  • Negative polarity items(NPIs), which function as quantifiers are licensed in a syntactically strict way by negatives, which function as qualifiers, resulting in universal negating interpretations as pairs. We present a proposal to explain the related phenomena, in which the syntax and the semantics are closely related to each other, with Combinatory Categorial Grammar. For this purpose, we first adopt the usual approach to scrambling, but control its overgeneration with the use of markers, taking into account the complex syntactic phenomena involving NPIs and scrambling in Korean. We also propose to utilize polarity intensity as a novel feature, in order to account for the universal negating interpretations when NPIs are combined with negatives. Our proposal also explains the difference in readings when other quantifiers or qualifiers intervene the NPI and the related negatives.

  • PDF

Characteristics of lightning Impulse Corona Discharges in SF6/CO2 Mixtures (SF6/CO2혼합기체 중에서 뇌임펄스코로나방전의 특성)

  • Lee, Bok-Hee;Baek, Young-Hwan;Oh, Sung-Kyun;Ahn, Chang-Hwan
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.20 no.1
    • /
    • pp.85-90
    • /
    • 2006
  • This paper presents experimental results relating to the preliminary breakdown characteristics in $SF_6/CO_2$ gas mixtures under a highly non-uniform electric field. The impulse pre-breakdown developments are investigated by the measurements of corona current and light emission images. As a result, the preliminary breakdown development mechanisms for both the positive and negative polarities were fundamentally same. The first streamer corona was initiated at the tip of needle electrode, and the leaders developed with a stepwise propagation and bridged the test gap. The pause time of leader pulses in the positive polarity was significantly shorter than that in the negative polarity. Also, the time interval between the first streamer corona onset and breakdown in the negative polarity was much longer than that in the positive polarity. The discharge channel path in the positive polarity was zigzag, and the leader channel in the negative polarity was thicker and brighter than that in the positive polarity.

The Study on Ending Repetition Construction ("-고 자시고"류 어미 반복 구성에 관한 연구)

  • Cho, Mihee
    • Korean Linguistics
    • /
    • v.76
    • /
    • pp.213-241
    • /
    • 2017
  • Korean verb 'Casi-', which is treated as negative element in dictionaries, is actually a placeholder shows indefinite use, and '-ko casiko' construction is understood as a member of a class of 'Ending repetition construction'. However, unlike among others, '-ko casiko' construction is now undergoing developement of its negative polarity. Because of its indefiniteness, '-ko casiko' construction change its meaning into a universal negative when it is used in negative sentences.

Characteristics of Dielectries in $SF_6$ Accoding to a change in Temperature (온도변화에 따른 $SF_6$ 가스의 절연특성)

  • Lee, Bok-Hee;Kim, Hoe-Gu;Park, Geon-Hun;Lee, Kyu-Sun;Kim, Dong-Sung
    • Proceedings of the KIEE Conference
    • /
    • 2007.07a
    • /
    • pp.1436-1437
    • /
    • 2007
  • This paper presents the experimental results of the dielectric characteristics with temperature changes under highly non-uniform electric field in $SF_6$ gas. The impulse preliminary breakdown developments were investigated by the measurement of predischarge current and breakdown voltage. As a result, the first stremer corona is initiated at the tip of needle electrode, and bridges the test gap. Also the first stremer corona onset and breakdown voltages the negative polarity was much higher than that in the positive polarity in same temperature. In addition, the varition of temperature have a little effect on the positive polarity. On the other hand, in some cases negative polarity corona onset and breakdown voltages increased with increasing a high temperature.

  • PDF

Characteristics of Electrical Discharge Machining of Ceramic Composites (세라믹 복합체의 방전가공 특성)

  • 우정윤;왕덕현;윤존도;안영철
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 1996.11a
    • /
    • pp.46-50
    • /
    • 1996
  • Die sinking Electrical Discharge Machining(EDM) of TiC/Al$_2$O$_3$Ceramic Matrix Composite(CMC) was conducted for positive and negative polarity according to the change of current and Duty Factor(DF). Also FEM analysis about temperature distribution of workpiece by one spark was executed. Maximum surface roughness( R$_{max}$ ) and SEM photographs of the EDMed surface for different conditions were evaluated. Higher Material Removal Rate(MRR) was obtained for negative polarity than positive one. Better surface morphology was found as the current is decreased, but the MRR was also decreased. From the SEM photographs, the size of melt cavity due to one spark is about 100 to 150${\mu}{\textrm}{m}$ in diameterer

  • PDF

Remarks on Defining Korean NPIs in terms of Negation Strength

  • Shin, Keun-Young;Chung, Dae-Ho
    • Language and Information
    • /
    • v.13 no.2
    • /
    • pp.47-57
    • /
    • 2009
  • It has been observed that not all negative polarity items (NPIs) are licensed in the same negative contexts, and different NPIs may be licensed by different negative expressions. This shows that Ladusaw's (1979) downward entailment is not precise enough to account for the distributional patterns of NPIs (van der Wouden, 1997; van der Wouden and Zwarts, 1993; Zwarts, 1986, among others). One well-known attempt to deal with this issue is to divide negative expressions into several subtypes. Using boolean semantics, Zwarts (1986; 1998) distinguishes three kinds of downward entailing licensors and accounts for heterogeneous NPI-licensing conditions by means of the semantic strength of negative expressions. This approach has been adopted to define Korean negation (Nam, 1994; Chung, 1993; Chung, 1997; Hwang, 2009). In this paper, however, we argue that the boolean semantic approach for negation is not adequate in characterizing the properties of Korean negative expressions and explaining the contexts of licensing Korean NPIs.

  • PDF

Characteristics of DC Corona Discharges Caused at the tip of a Needle-shaped Electrode Placed in the Homogeneous Electric Fields (균등전계 중에 놓인 침상 전극의 끝단에서 발생한 직류 코로나방전 특성)

  • Kim, Tae-Ki;Kim, Seung-Min;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.29 no.11
    • /
    • pp.74-81
    • /
    • 2015
  • In the measurement of atmospheric static electric field, it is important to know characteristics of corona discharges caused at the tip of test electrode. This paper presents the fundamental data of DC corona discharges that occurred at the tip of a needle-shaped electrode placed in the homogeneous background electric field which simulates the atmospheric static field under thundercloud. The major characteristics of interest for this purpose are the polarity effect of corona discharges and the magnitudes and time intervals of corona current pulses. The experimental set-up consists of the plate-to-plate configuration with a needle-shaped protrusion, DC power supply, and voltage and current measuring devices. As a result of experiments, the polarity dependence of corona pulses is significantly pronounced. The time intervals between successive corona pulses in the negative polarity is much longer than those in the positive polarity. The time intervals for both polarities is drastically decreased as the applied electric field is increased. Also the magnitudes of the positive corona pulses are slightly changed with an increase in applied electric field, but those of the negative corona pulses are linearly increased with increasing the applied electric fields.