• 한국환경과학회지
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• 제4권2호
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• pp.169-180
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• 1995

This Daper presents effective simulation of the dispersion of thermal discharge which can be relesed at Boryong power plant. Applied numerical models are finite difference method for hydrodynamic analysis and Masch-model comprised of conditions for ambient current velocity. Application of these models is done in Cheonsu Bay Summing up the results of this study are as follows; 1. It is found that the result for measurements of temperature appears high at southwardly Songdo on flood. The reason is that tidal currents which flowed north direction were accompanied with southwardly dispersed thermal discharge. A minute Particle of thermal Plume has a tendency to dispels inward Deacheon Bay. 2. According to the results of numerical experiment, maximum distance for thermal discharge dispersion appeared 10.8 km at lower part and 8.6 km at upper part with power plant outlet as starting point. 3. Comparative the numerical simulation and Airbone Multispectral Scanner indicated that thermal discharge should be verified separative phenomena. The simulated results were compared with field data set showing good agreement. It is concluded that these model can be simulated well.

• Journal of Information Display
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• 제2권2호
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• pp.39-44
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• 2001

The conditions of the wall charges and priming particles in a unit discharge cell in AC PDP seriously affect the addressing discharge characteristics in the driving method with ramped setup pulse. Moreover, the discharge conditions at the end of the scan line may be different from the first scan line because of the difference of about 1ms address time. Consequently, the addressing time and its dispersion may be different for any two discharge cells that lead to misfiring and the increase in the total addressing time. In order to improve the addressing time and its dispersion, we have applied different addressing voltage at each cell such as progressively increase pulse voltage instead of constant one. As a result, the addressing time and its dispersion of all cells were improved by about 30% compared with the conventional driving method.

• 물과 미래
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• 제16권4호
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• pp.237-243
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• 1983

본 연구는 수리모형 실험을 통하여 지류로부터 유입 된 오염원이 합류후에 여하히 의석확산하는 가에 대하여 규명하였다. 본류와 지류의 유량을 변화시키면서 정성적인 확산경향, 유황, 유속, 수리적인 특성을 관찰하였다. 희석확산의 결과는 오염원으로부터의 거리 및 오염의 진행시간에도 많은 영향을 받으나 무엇보다도 그 지점의 유체의 유속이 빠를수록 그리고 유량비가 클수록 오염물질의 희석확산의 효과는 크게 나타났다. 또한, 유속이 커질수록 종방향의 확산속도는 상대적으로 증가하고 횡방향의 확산속도는 감소된다. 이는 속도 분포에 의한 확산이 커지기 때문인 것으로 사료된다.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1598-1602
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• 2009

The particle size of Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode powder was controlled effectively by dispersion using lauric acid as a surfactant. The samples treated by lauric acid showed smaller particles of approximately half the original size compared to the particles of a pristine sample. A structural change due to the dispersion of Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ powder was not detected. The rate performance of the Li[$Ni_{0.2}Li_{0.2}Mn_{0.6}]O_2$ cathode was improved by dispersion using lauric acid, which was likely due to the decrease of the particle size. In particular, a sample dispersed pristine powder using lauric acid (L2) presented a greatly enhanced discharge capacity and capacity retention at a high C rate. The discharge capacity of a pristine sample was only 133 m$Ahg^{-1}$ (3C rate) and 96 m$Ahg^{-1}$ (12C rate) at the tenth cycle. In contrast, the L2 electrode delivered higher discharge capacities of 160 m$Ahg^{-1}$ (3C rate) and 129 m$Ahg^{-1}$ (12C rate) at the tenth cycle. The capacity retention at a rate of 12C/2C was also enhanced from ~ 45% (pristine sample) to 57% (L2) by treatment with lauric acid.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.491-491
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• 2013

A novel plasma system has been developed for 3-dimensional modification of the carbon nano-powders. Improvement of dispersion of these nano materials are studied by plasma discharge, not using chemical modification. The plasma process is considered to great advantages over wet chemical process due to environmental, economic viewpoint, and uniformity over the treated volume. The uniform dispersion is a critical factor for these material's nano composite applications. Using this plasma system, graphene, carbon black, and CNT was treated and functionalized. Several key discharge conditions such as Ar/H2/O2 or Ar/H2/NH3 gas ratio, treatment time, power, feeder's vibration frequency are investigated. Hydrophobic of graphene has turned some more into hydrophilic by reaction test with water, electrophoresis, surface contact angle test, and turbidity analysis. The oxygen content ratio in the plasma treated CNT has increased about 3.7 times than the untreatedone. In the case of graphene and carbon black, the oxygen- and nitrogen- content has been enhanced average 10%. O-H (N-H) peak, C-O (C-N) peak, and C=O (C=N) peak data have been detected by FTIR measurement and intensified compared to before-plasma treatment due to O2 or NH3 content.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.3-6
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• 2001

Various Parameters such as stream velocities, discharges, and dispersion coefficients of dissolved solutes were estimated by fitting 1-D nonreactive solute transport model to the time-series chemistry data. This study was done for the reaches of Mankyung River lower than the Jeonju Wastewater Treatment Plant (Jeonju WTP). Korea. Concentrations of inorganic chemicals in the stream waters are strongly influenced by mixing with the chemically distinct effluent from Jeonju WTP. Sulfate, EC. and the total major cation were proved to be nearly conservative in the study area front their relationships with chloride, the conservative chemical species. The solute transport model was constrained to the time-series concentrations for these 4 conservative species. The variations of concentration and discharge of Jeonju WTP were used as input parameters, and the stream velocities, dispersion coefficients, and concentrations and discharges of some inflows were optimized. The differences between the observed arid simulated values for alkalinities and nitrates are inversely correlated and show diurnal fluctuations, indicating the photosynthesis. The parameters obtained front this mode] range from 550 to 774 kcmd (stream discharge at the outlet of the study area), from 0.06 to 0.10 m/sec (flow velocity), and from 0.7 to 6.4 m$^2$/sec (dispersion coefficient). The history of Jeonju WTP discharge was well predicted when optimized, indicating the validity of the model results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1586-1588
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• 1994

Some interesting corona characteristics of a airgap of penpoint-to-plate with a tracing insulator paper has been investigated in a temperature and humidity controlled metal chamber. It is found that the positive and the negative carriers in the plasma region could be understood from the waterdrop traces on the paper, which indicate the bombardment by the one of electron or positive gas particle from the plasma region of near the point. It is also found that a corona discharge could be used as a means of a humidifying, since the discharge makes dispersion of watersprays from the penpoint. And the negative corona was more effective for waterspray dispersion than the positive ones.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.35-41
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• 2015

This paper presents a breakdown voltage and a process of breakdown progress in mineral oil under an quasi-uniform field with decomposition products which occur after the oil discharge. The breakdown voltage in the oil revealed the characteristics of dispersion regardless of an electrode gap. The cumulative probability distribution was used to analyze the dispersion of the breakdown voltage. In addition, the process of breakdown progress in the oil can be reasonably described by the electron breakdown theory based on both electrons emitted from the cathode and ions by field-aided dissociation of the oil. The proposed breakdown process will be used for the basic data to explain the behavior pattern of the decomposition product to cause the dispersion of the breakdown voltage.

• 한국가스학회지
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• 제16권4호
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• pp.59-64
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• 2012

LPG 저장설비에 부착된 압력방출밸브 방출관으로부터 분출된 가스의 확산에 대해 검토하였다. 통상 방출관은 안전한 장소인 수직 상방향으로 분출되도록 설치되어야 하며, 방출된 가스가 착화되더라도 저장탱크, 장치, 배관에 화염이 닿지 않도록 설치되어야 한다[1][2]. 그러나 우리나라에서는 방출구를 통한 분출방향에 대한 기준이 없이 다양한 방출구 형태가 존재한다. 따라서, 본 연구에서는 4가지 방출방향 즉 수직상방, 수직하방, 수평 2, 수직 4방향에 대해서 고려하였다. 방출구로부터 분출된 가스의 확산 시뮬레이션은 상용소프트웨어인 FLACS를 사용하였다. 이를 통해 수직하방, 수평 2, 수직 4방향으로 분출하도록 방출구를 설치하는 것은 지면에서의 착화를 방지하는 데 불리한 것으로 나타났다. 따라서 안전밸브로부터 분출된 가스를 방출구를 통해 안전하게 분출하기 위해서는 수직상방으로 분출되는 것이 최선임을 알 수 있었다.

• 한국방재학회 논문집
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• 제4권3호
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• pp.43-50
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• 2004

본 연구에서는 갈수시 하천에 순간적으로 유입되는 오염물질에 대해 댐방류량 변화에 따른 플러싱 효과를 분석하였다. 한강하류부(잠실수중보${\sim}$신곡수중보)에 RMA-2 및 RMA-4 모형을 적용하였으며, 유로특성을 반영할 수 있도록 종확산계수는 $50m^2/s$을 사용하였다. 댐방류량은 1시간동안 $500m^3/s,\;1000m^3/s,\;1500m^3/s,\;2000m^3/s$로 변화시켰으며, 갈수시 유량은 $200m^3/s$로 고정하였다. 정체되어 있는 경우와 순간적으로 유입되는 경우, 성산대교 부근에서 농도가 1ppm 이하로 떨어지는 시간을 각 유량별로 분석하였다. 댐방류량이 증가할수록 희석시간이 단축되는 것을 알 수 있었고, 댐방류량과 희석시간이 선형관계가 있는 것으로 나타났다. 순간적으로 유입된 오염물질이 정체된 오염물질의 경우보다 댐방류량에 민감하게 영향을 받으며, 댐방류량에 의한 플러싱을 시도할 경우에는 본류의 오염물질이 지류로 역류하는 범위를 파악할 수 있었다.