• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.1
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• pp.42-49
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• 1992

Charge accumulation characteristics in low density polyethylene (LDPE) has been discussed based upon the internal charge distrubution measured by the pulsed electroacoustic technique. When the negative voltage with respect to earth is applied to the upper electrode, the negative charges near the anode and the positive charges near the cathode are accumulated in LDPE. Also, there was an asymmetric behavior of charge accumulation exhibiting that the charge accumulation near the anode keeps increasing whereas that near the cathode increases first and then decreases. Besides, under the present test conditions the internal charge distrubution becomes stabilized eventually. When the positive voltage with respect to earth is applied to the upper electrode, on the other hand, no such asymmetric charge accumulation was found. Therefore, it can be concluded that the heterocharges are accumulated at the surface region of LDPE subjected to high do voltages and that the begavior of charge accumulation depends on the polarity of do voltage and the position of charge accumulation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.145-146
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• 2005

This study performs a simulation for an accumulation mechanism of contaminants, which were produced in an industrial belt of inland, on the surface of insulators. From the simulation, silicon insulators presented higher accumulation than that of EPDM(Ethylene Propylene Diene Terpolymer : EPDM) insulators on the same distance in the case of the Virgin polymer insulator, and this result presented the same result in the insulator applied in actual fields. In the case of the accumulation test for the Virgin insulator and insulators used in actual fields, it is evident that the Virgin insulator presented more accumulation than that of the insulator used in actual fields. The results can be caused by the generation of LMW (Low Molecular Weight) on the external material of polymer insulators, and the level of the accumulation can be changed according to the degree of the continuous generation of LMW.

• Journal of Environmental Science International
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• v.12 no.7
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• pp.745-751
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• 2003

The three-dimensional eco-hydrodynamic model was applied to estimate the physical process in terms of nutrients and net uptake(or regeneration) rate of nutrients in Kamak Bay for scenario analysis to find proper management plan. The estimation results of the physical process in terms of nutrients shelved that transportation of nutrients is dominant in surface level while accumulation of nutrients is dominant in bottom level. In the case of dissolved inorganic nitrogen, the results showed that the net uptake rate was 0∼60 mg/㎡/day in surface level(0∼3m), and the net regeneration rate was 0.0∼10.0 mg/㎡/day in middle level(3∼6m) and above 10mg/㎡/day in bottom level(6m∼below). In the case of dissolved inorganic phosphorus, the net uptake rate was 0.0∼3.0 mg/㎡/day in surface level, and the net regeneration rate was 0.5∼1.5 mg/㎡/day in middle level and 1.0∼3.0 mg/㎡/day in bottom level. These results indicates that net uptake and transport of nutrients are occurred predominantly at the surface level and the net generation and accumulation are dominant at bottom level. Therefore, it is important to consider the re-supplement of nutrients due to regeneration of bottom water.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.61-66
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• 1999

반복 응력 상태 아래서 알루미나 세라믹의 피로 표면손상 누적현상이 분석되었다. 연속 미끄럼 접촉 시에 발생하는 응력 상태를 재현하기 위해서 동시에 작용하는 수직-수평 반복 압축하중 기법이 사용되었다. 알루미나 구와 평판의 접촉면에서 알루미나 미세 결정의 피로 파손에 의한 마모 입자 형성 기구가 관찰되었고, 반복하중의 횟수와 수직-수평 하중비가 커질수록 마모량은 증가하였다. 반복 접촉하중에 의한 표면손상 누적이 접촉 수직 변위 측정으로 정량화 되었다. 두 접촉 구조물의 강성 (하중-변위 선도의 기울기) 변화가 두 재질의 탄성계수의 변화로 표현되었다.

• Journal of Electrical Engineering and Technology
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• v.11 no.5
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• pp.1332-1336
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• 2016

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.427-430
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• 2002

This paper presents on contamination performance of polymeric outdoor insulator with different contaminant accumulation. The ESDD (equivalent salt deposit density), tracking resistance and clean-fog test were performed to investigate the characteristics of contamination performance on polymeric outdoor insulator. Furthermore, we evaluated together with the porcelain samples for its comparison. It is found that ESDD of polymeric and porcelain insulator depends on the installation position. This surface accumulation of contaminant lead to the loss of surface hydrophobicity, expecially upper shed part of polymeric insulator. In addition, the effect of an artificial contaminant on the tracking resistance by inclined-plane method and leakage suppression ability under clean fog was surveyed. The time of tracking failure did not appear to change significantly with a much contaminant accumulation, while leakage current under clean-fog increased.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.360-364
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• 2006

The physical characteristics of suspended solid in urban watersheds are estimated and are described the accumulation processes on the urban surface. And build up the accumulation model which has two parameters and three constants. Two parameters are $p_0\;and\;p_{max'}$, and three constants are landuse, clean and traffic constant. Suggested model is applied three industry watershed which has variable area. And simulated results are compared with observed data. The model estimates the real phenomenon and the results are pretty good. The simulated accumulation mass are 1.20, 0.96 and $2.88g/m^2$. The differences of simulation and observation data are about 30%.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1681-1683
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• 1998

Unlike AC, DC dielectric characteristics of the spacer are very influenced by the quantity and the distribution of surface charges. A general impression of the distribution of surface charges is obtained if electrostatic powders are sprinkled over the surface. The distribution of surface charge was investigated with dust figures. Mechanism of charge accumulation on the spacer of $SF_6$ GIS has been studied using various types of model spacers which have different depths. As a result, it was found that charge accumulation was dominantly influenced by the normal component of the electric field and the usage of embedded electrodes was an adequate method to lessen field concentration around the triple junction. The guide of the optimum depth of the spacer was proposed.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.134-143
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• 1993

The trajectory planning for the manipulator installed on "the automatic pothole repair vehicle" is discussed and the final surface of the patched pot hole is simulated in this work. The relationship between the accumulation data of the mixture with and without the movement of the manipulator is identified to utilize the latter data for the calculation of the former one. Based on this relationship, the method to calculate the accumulation of the mixture when the manipulator changes the speed and the direction is also introduced. The trajectory is determined to make the final surface smooth under the condition that the pothole is cut to hexahedron before patching and only the spacing and the shifting of the manipulator is controllable. Final surface is simulated by the computer to prove the adequacy of the determined trajectory.

• Journal of the korean society of oceanography
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• v.34 no.4
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• pp.214-219
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• 1999

Cells of the dinoflagellate Gyrodinium impudicum form characteristic chains, which are associated with sugar accumulated on the cell surface. To resolve the relationship between chain-formation and cell surface sugar accumulation, confocal microscopy was used to observe sugar accumulation points in the vegetative cells and long chain-forming cells of G. impudicum cells treated with fluorescent-tagged ConA. In the stationary and exponential phases, both vegetative cells and chain-forming cells were similar to each other in fluorescent intensity. There was no evidence that chain-forming cells had a specific location for sugar accumulation on the cell surface. Most of the cells formed 2-cell chains one day after inoculation, but longer chains consisting of 4-8 cells increased markedly in 4day and 8 day cultures. Gyrodinium impudicum chains usually consist of more than four cells, and chains of 8 or even 16 cells can be observed in mature cultures. Temperature played an importantrole in chain-formation of the cells, threshold temperature for the development of long chain-formation was 19 $^{\circ}$C.