• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.994-999
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• 2011

The main wearing slider of pantograph is a difference which is considerable to wear phenomenon according to material properties. Especially, Cu-type wearing slider suddenly occurs the abnormal wear by precipitation, this threatens the travelling safety of the train. The abnormal wear by precipitation and arc influences are main factor decided to life time of Cu-type wearing slider and contact wire. Consequently, the application of the main wearing slider with wear resisting capacity, electrical conductivity, resistance arc and lubrication is demanded. In this paper through tribologic approach, overcame abnormal phenomenon of the Cu-type wearing slider by the precipitation and for the economic efficient augmentation by durability improvement and the travelling safety were accomplished. The Cu-type wearing slider which has excellent electric conductivity and arc characteristic but it occurs the normal and abnormal wear phenomenon according the precipitation which changes, respectively. Consequently, this phenomenon grasps fixed quantity according to precipitation, a mileage and wear volume then Fe-type wearing slider compared and analyzed.

• 연구논문집
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• 통권28호
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• pp.39-47
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• 1998

Industrial electrostatic precipitation is a very complex process, which involves multiple-way interaction between the electric field, the fluid flow, and the particulate motion. This paper describes a strongly coupled calculation procedure for the rigorous computation of particle dynamics during electrostatic precipitation. The turbulent gas flow and the particle motion under electrostatic forces are calculated by using the commercial computational fluid dynamics (CFD) package FLUENT linked to a finite-volume solver for the electric field and ion charge. Particle charge is determined from both local electrical conditions and the cell residence time which the particle has experienced through its path. Particle charge density and the particle velocity are averaged in a control volume to use Lagrangian information of the particle motion in calculating the gas and electric fields. The turbulent particulate transport and the effects of particulate space charge on the electrical current flow are investigated. The calculated results for poly-dispersed particles are compared with those for mono-dispersed particles, and significant differences are demonstrated.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2000년도 추계학술대회
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• pp.302-306
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• 2000

In case of applying electrokinetic remediation, magnitude of electric current is one of major factors for estimation of contaminant transport. In practice, electric current provide determination of electric conductivity based on specimen resistance. Electric current variation is produced during Electrokinetic remediation test. Electric current is decreased by expotential function according to time in condition of constant voltage. This can be interpreted as precipitation effect by OH$^{-10}$ generation in a cathode.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
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• pp.9-12
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• 2000

A new type electrolyzing cell with slits on parallel plate electrodes and wire-to-cylinder type electrode system has been proposed instead of the conventional parallel plate type. An investigation was carried out on the effect of the number and size of slits on ion precipitation and oxidant generation characteristics, evidenced by eliminated space charge limiting action and by elevated electric fields in active interelectrode spacing. And it is also studied on the effect of the diameter of wire electrode to ion precipitation and oxidant generation characteristics. With electrode with 48 slits, very oxidants generation water of 3.1 [ppmm] and 19.0 [ppmm] in positive electrode side were obtained with tap water and 0.1 [wt%] NaCl dissolved tap waterfed. In addition, with wire-to-cylinder type electrode system, it is found that oxidant contained water of 0.48 [ppmm] and 5.46 [ppmm] in positive electrode side were obtained with tap water and 0.1 [wt%] NaCl dissolved tap water fed for the case of discharge electrode diameter of 0.5 [$mm{\phi}$]. Consequently, very high ion precipitation and dense oxidant generation characteristics can be realized by having slits on the electrodes of conventional cell as these slits increase the electric fields and decrease the space charge limiting actions in interelectrode spacing.

• 한국환경보건학회지
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• 제22권4호
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• pp.62-68
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• 1996

Precipitation samples were collected by the wet-only event sampling method at Seoul from September 1991 to April 1995. Concentrations of samples for the ion components($NO_3^-, NO_2^-, SO_4^{2-}, Cl^-, F^-, Na^+, K^+, Ca^{2+}, Mg^{2+}$ and $NH_4^+$) were measured in addition to pH and electric conductivity. During the sampling period, 182 samples were collected, but only 163 samples were identified as valid. The pH, calculated from the volume-weighted $H^+$ concentration, was found to be 4.7, indicating a relatively intensive acidity compared with data from other regions of the world, where acid deposition was known to be a problem. Above all, the concentration of non-seasalt sulfate was $84 \mu eq/L$, which was the highest compared to that measured in other regions of the world. The major acidifying ions in the precipitation at Seoul were identified as sulfate and nitrate except for chloride, because the Cl/Na ratio in the precipitation was close to the ratio in seawater. If all of the non-seasalt sulfate and nitrate existed in the form of sulfuric and nitric acids, respectively, the average pH in the precipitation was calculated as 3.7, lower than the measured value. Consequently, the difference between the calculated and measured pH suggest that the acidity of precipitation was neutralized by alkaline species, not due to the low contribution of an anthropogenic air pollutants to the precipitation. The equivalent concentration ratio of sulfate to nitrate was 3.5, which indicated that the contributions of sulfuric and nitric acids to the precipitation acidity were 78% and 22%, respectively.

• 한국대기환경학회지
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• 제22권1호
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• pp.15-24
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• 2006

Precipitation samples were collected at Anmyeon (1997 - 2004), Uljin, and Gosan (1998 ~ 2004), the background area of the Korean Peninsula. These samples were analyzed for the concentration of 9 major ionic components ($F^{-}$,$Cl^{-}$, $NO_{3}^{-}$, $SO_{4}^{2-}$, $Na^{+}$, $NH_{4}^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$) with including a pH and an electric conductivity. Data quality for these samples was verified by ion balance and conductivity balance which are based on GAW manual for precipitation chemistry and the number of valid data at Anmyeon, Uljin, and Gosan is 249, 173, and 188, respectively. During the study period, the precipitation-weighted average pH at Anmyeon, Uljin, and Gosan was found to be 4.81, 4.87 and 4.89, respectively and each annual average pH was showed below pH 5.6 for every site. From the frequency survey on the precipitation acidity, the occurrence rate of acid rain below pH 5.6 is greater than $80\%$ for every site. Particularly, the highest occurrence rate for strong acid rain below pH 4.5 was found at Anmyeon, $32.1\%$, compared with other sites ($10.4\%$ at Uljin, $15.4\%$ at Gosan). That's because acidifying species (nss-$SO_{4}^{2-}$, $NO_{3}^{-}$) are remarkably high concentration at Anmyeon.

• International Journal of Internet, Broadcasting and Communication
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• 제15권3호
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• pp.239-245
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• 2023

In this research, our objective was to investigate the efficacy of electrostatic precipitation in capturing mist particles. We assumed that it could be helpful in multi-functional facilities and similar environments where both humidification and dehumidification are required. We derived the air density of the humidified air based on its properties using Dalton's law. The analysis was performed to evaluate the collection efficiency of capturing mist aerosols of various sizes. As a result, we revealed that under the conditions of a dry-bulb temperature of 26.0℃ and relative humidity of 8%, the system achieved a collection efficiency of 99.999% or more for aerosols larger than 2.5㎛. These results indicate that electrostatic precipitation technology shows great promise as an effective method for capturing mist particles.

• 조명전기설비학회논문지
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• 제22권12호
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• pp.122-129
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• 2008

본 논문은 실내에 잔존하는 직경 1[${\mu}m$] 이하의 미세먼지들을 집진하기 위하여 전기집진기를 설계하였으며, 이때 집진 효율의 극대화를 위하여 전계와 동시에 자계를 수직 및 수평으로 배치함에 따른 실험실 공기중에 포함된 미세먼지의 집진특성에 대하여 논하였다. 전계에 수평으로 자계를 인가한 경우는 자계의 유무 및 자석의 수량에 관계없이 집진효율이 거의 일정하게 나타났으며, 자석을 수평으로 배치하여 전계에 수직으로 인가한 경우는 비자화 페라이트 막대를 부착한 경우보다 약 5[%] 이상 집진효율이 향상되었다. 또한, 자계를 전계에 수직으로 인가하는 방법에 있어서, 자석을 접지전극의 가운데 정렬한 경우는 인가전압 5[kV]에서의 집진효율이 $17{\sim}32[%]$로서 자석을 앞쪽에 설치한 경우와 유사하였으며, 지그재그 및 안쪽 끝에 정렬시킨 경우는 집진효율이 $17{\sim}38[%]$로서 향상되었으며, 특히 0.7 및 1[${\mu}m$]의 굵은 입자들에 대한 집진특성이 양호하였다. 따라서, 전기집진기의 집진특성을 향상시키기 위해서는 자계를 전계에 수직으로 접지전극의 중간 또는 지그재그 식으로 배치하는 것이 가장 적절한 것으로 판단된다.

• 조명전기설비학회논문지
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• 제16권4호
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• pp.101-107
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• 2002

본 논문은 종래형 전해수 발생장치의 평판전극을 슬릿형 평행평판전극 구조로 함으로써 고효율의 강전해수 발생장치를 제안하였다. 염화나트륨이 용해된 수도수와 일반 수도수를 본 강전해수 발생장치에 인입하였을 때 전해수 생성공간내의 공간전하제한작용을 크게 감소시키면서 또한 이 전해수 생성공간내의 전계분포를 집중시킬 수 있는 슬릿형 평행평판전극을 설정하고, 이러한 슬릿의 형태와 개수증가가 수중 이온분리집속성능에 미치는 영향과 산화성물질 생성에 미치는 영향을 연구 검토하였다. 실험결과 수중 강전해수 발생장치내에 슬릿을 형성함으로써 전해수 발생공간내의 전계를 집중시키고 분리집속된 고농도의 이온들에 의한 공간전하 제한작용을 크게 감소시켜 저전력에서 기존의 전해수 발생장치보다 훨씬 고농도의 강전해수와 산화성물질 용존수를 얻을 수 있었다.

• 한국대기환경학회지
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• 제13권1호
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• pp.9-18
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• 1997

Precipitation samples were collected by the wet- only event sampling method from Seoul during September 1991 to April 1995. These samples were analyzed for the concentrations of the major ionic components (N $O_3$$^{[-10]}$ , N $O_2$$^{[-10]}$ , S $O_4$$^{2-}$, C $l^{[-10]}$ , $F^{[-10]}$ , N $a^{＋}$, $K^{+}$, $Ca^{2＋}$, $Mg^{2＋}$, and N $H_4$$^{＋}$), pH, and electric conductivity. During the study period, a total of 182 samples were collected, but only 163 samples were used for the data analysis via quality assurance of precipitation chemistry data. The volume-weighted pH was found to be 4.7. The major acidifying species from our precipitation studies were identified to be non-seasalt sulfate (84$\pm$9 $\mu$eq/L) and nitrate (24$\pm$2 $\mu$eq/L) except for chloride. Because the Cl/Na ratio in the precipitation was close to the ratio in seawater. If all of the non-seasalt sulfate and nitrate were in the form of sulfuric and nitric acids, the mean pH in the precipitation could have been as low as 3.7 lower than the computed value. Consequently, the difference between two pH values indicate that the acidity of precipitation was neutralized by alkaline species. The equivalent concentration ratio of sulfate to nitrate was 3.5, indicating that sulfuric and nitric acids can comprise 78％ and 22％ of the precipitation acidity, respectively. Analysis of temporal trend in the measured acidity and ionic components were also performed using the linear regression method. The precipitation acidity generally showed a significantly decreasing trend, which was compatible with the pattern of the ratio (N $H_4$$^{＋}$＋C $a^{2＋}$)/ (nss-S $O_4$$^{2-}$＋N $O_3$$^{[-10]}$ ).).