• 한국표면공학회지
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• 제29권4호
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• pp.219-228
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• 1996

Neutral Zinc Electroplating(NZE) utilizing the electrolyte of pH 6 to 8 has advantages in waste treatment and the protection of equipment. NZE is beneficially used in chromating treatment, but the limiting current density and the current efficiency are low. Therefore this study is investigated to analyse the characteristics of NZE and to obtain high current density and current efficiency. The deposition potential of zinc in the NZE bath is about 110mV, which is lower than acidic bath. The current density possibily increases up to 60A/d$\m^2$ in lower complexing agent content and pH 6. More than 90% of cathodic current efficiency was obtained in NZE bath. The NZE morphology shows smaller grains than acidic bath. The addition of 4$m\ell$/1 second brightener gives finer morphology. As pH becomes higher, (002) plan decreases and (100), (101) and (110) planes increase in the no additives solution.

• 한국안전학회지
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• 제7권2호
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• pp.57-62
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• 1992

In this thesis, the electrification phenomenon was studied by measurement of charging current and discharging current in polymers when the carriers generated by corona discharge were supplied to the surface of polymers. Corona charging current of PVC, polar and noncrystalline polymer, was larger than that of nonpolar and amorphous polymers. Corona charging current on the specimen of naked upper surface (CIM) was larger than charging current on the specimen of electrode made. Carrier injection differed from interfacial phase of polymer surFace. The transfer phenomenon vaned with chemical structure of polymer and then the polar effect of PVC was remarkable because of large electron affinity of Cl. In the characteristics of discharging current of PVC, the abnormal current was observed. It was supposed that this phenomena presented the trap of injected carriers in PVC and that static electricity phenomenon was generated by trap.

• Journal of Power Electronics
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• 제16권3호
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• pp.1004-1011
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• 2016

The inaccurate model parameters in the predictive current control of surface-mounted permanent magnet synchronous motor (SMPMSM) affect the current dynamic response and steady-state error. This paper presents a model parameter correction algorithm based on the relationship between the errors of model parameters and the static errors of dq-axis current. In this correction algorithm, the errors of inductance and flux are corrected in two steps. Resistance is ignored. First, the proportional relations between inductance and d-axis static current errors are utilized to correct the error of model inductance. Second, the flux is corrected by utilizing the proportional relations between flux and q-axis static current errors under the condition that inductance is corrected. An experimental study with a 100 W SMPMSM is performed to validate the proposed algorithm.

• 한국표면공학회지
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• 제34권4호
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• pp.303-312
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• 2001

Composition and microstructure of the tin-zinc alloys electroplated in gluconate bath were studied according to pulse current parameters. The cathode current efficiency increased with both the mean current density and the off-time decrease. Zinc content of the alloy deposits increased with increasing mean current density, while it decreased noticebly with increasing the off-time from 10-30ms to 100-150ms. The preferred orientation of the alloy deposits changed with the increase of peak current density in the sequence of (220)longrightarrow(220)+(420) or (220)+(420)+(321) mixed structure. The equiaxed grain size of the alloy increased with the increase of off-time and the decrease of mean current density.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제21권1호
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• pp.67-76
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• 2015

Purpose : The current tactile walking surface indicators have not been easily accessible to blind and vision-impaired people due to unexpected variation of walking environment and walking behavior of transportation poor. Moreover, those indicators frequently cause the inconvenience to transportation users' walking. Thus, this study aims to investigate the improvement of tactile walking surface indicators, by comparing and analyzing findings from the relevant research. Results from this study contribute to suggest the better standard criteria of tactile walking surface indicators for transportation users, especially blind and vision-impaired people, the handicapped, the child and the elderly and weak, providing the secure and convenient circumstance for walking. Method : This study presents the problems about the standard criteria of tactile walking surface indicators via the examination of finding from the past studies. For example, we examine all standard criteria, focusing on shapes, colors and qualities of materials used for Tactile Walking Surface Indicators. Then, the present study suggests the improvement of standard, which apply to the current walking environment practically and reasonably. Results : To improve the current condition of tactile walking surface indicators, the analysis on international and domestic standard criteria need to be conducted. Findings from these analyses helps to suggest the better criteria for the interval between projecting points of tactile walking surface indicators, effective perceived range of walking road, and the brightness contrast between tactile walking surface indicators and finishing materials. Implication : The suggested standard criteria of tactile walking surface indicators need to be tested by transportation users, and the practical instructions of establishing tactile walking surface indicators should also be developed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1621-1623
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• 1999

Recently, high voltage outdoor ploymer insulators have been widely used commercially owing to their excellent electrical and mechanical properties, superior comtamination flashover performance, light weight, easy installation or handing, no maintenance during service, competitive price and so on. compared to porcelaain and glass insulators. For instance, silicone rubber(SR) for polymeric insulators specially has much superior insulating and anti-pollution performance due to its specific hydrophobicity even in severe contaminated environments. We have investigated surface discharge current characteristics of silicone rubbers(SR) for HV outdoor composite insulation specimen under accelerated aging codition using a computer measuring system. The relations of average leakage current and surface discharge current repetition rates and discharge current amplitude, the distribution of discharge current amplitude were studied to investigate electrical conduction of silicone rubber surface with the salt fog condition.

• International Journal of Precision Engineering and Manufacturing
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• 제2권1호
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• pp.18-25
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• 2001

Electrolytic polishing is the anodic dissolution process in the transpassive state. It removes non-metallic inclusion and improves mechanical and corrosion resistance of stainless steel. If there is a Bailby layer, it will be removed and the true structure of the surface will be restored. Electrolytic polishing is normally used to remove a very thin layer of material from the surface of metal object. A new electrolyte composed of phosphoric, sulfuric and distilled water has been developed in this study. Two current density, high & low current density regions, have been applied in this study. In this study, In the region of high current density, there is no plateau region but excellent electrolytic polishing effect can be accomplished in short machining time because material removel process and leveling process occur simultaneously. In the low current density region, there can be found plateau region. The material removal process and leveling process occur successively. The aim of this work is to determine electrolytic polishing for stainless steel in terms of high & low current density and workpiece surface roughness.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.758-762
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• 1998

Electrical conduction property of insulator surface is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the materials to be used for outdoor insulator such as porcelain, EPDM, silicone rubber was discussed by measuring properties of average leakage current and scintillation discharge pulses under salt fog conditions. The fog was applied by nozzle in chamber and fogging fluids were deionized distilled water, 0.5wt% NaCI solution and 2wt% NaCl solution. The average leakage current showed linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage were much different to those in case of dry and clean condition with 2wt% salt fog. In case of slat fog pollution condition, the leakage current was increased above critical voltage. the scintillation discharges were also activated at the level. The leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• Wind and Structures
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• 제12권3호
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• pp.179-204
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• 2009

A physical and numerical steady flow impinging jet has been used to simulate the bulk characteristics of a downburst-like wind field. The influence of downdraft tilt and surface roughness on the ensuing wall jet flow has been investigated. It was found that a simulated downdraft impinging the surface at a non-normal angle has the potential for causing larger structural loads than the normal impingement case. It was also found that for the current impinging jet simulations, surface roughness played a minor role in determining the storm maximum wind structure, but this influence increased as the wall jet diverged. However, through comparison with previous research it was found that the influence of surface roughness is Reynolds number dependent and therefore may differ from that reported herein for full-scale downburst cases. Using the current experimental results an empirical model has been developed for laboratory-scale impinging jet velocity structure that includes the influence of both jet tilt and surface roughness.

• Applied Science and Convergence Technology
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• 제25권6호
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• pp.133-137
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• 2016

The surface treatment of cover glass for conversion efficiency of photovoltaic cell is important to reduce reflectivity and to increase the incident light. In this work, random textured anti glare (RTAG) glass was prepared by wet surface coating method. Optical properties due to the changes of surface morphology of RTAG glass were compared and conversion efficiency of photovoltaic cell was researched. Grain size and changes of surface morphologies formed with surface etching time greatly affected optical transmittance and transmission haze. Current density (Jsc) were high at the condition when surface morphologies reflection haze were low and transmission haze were high. Jsc was $40.0mA/cm^2$ at glancing angle of $90^{\circ}$. Incidence light source was strongly influenced by surface treatment of cover glass at high incidence angle but was hardly affected light source at the low angle of incidence.