• Title/Summary/Keyword: the distribution of water flow

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A Study on the Improvement of Huff's Method for Applying in Korea : II. Improvement of Huff's Method (Huff 강우시간분포방법의 개선방안 연구 : II. Huff 방법의 개선방안)

  • Jang Su-Hyung;Yoon Jae-Young;Yoon Yong-Nam
    • Journal of Korea Water Resources Association
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    • v.39 no.9 s.170
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    • pp.779-786
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    • 2006
  • In this study, we propose a new method that utilizes rainfall data in and out of a basin, which is greater than 25.4mm for point rainfall or 12.7mm for areal mean rainfall respectively. From our analysis, most frequent quartile for point and areal mean rainfall were found to be the same in general for various rainfall duration intervals. From an evaluation of design rainfall per each rainfall duration distributed in time by the MOCT(Ministry of Construction and Transportation) version of Huff's method and this study, peak rainfall intensity by this study was found to be greater than the one by MOCT, but there were no consistent increase or decrease of this difference with rainfall durations. Using the distributed design rainfall per each duration by MOCT and this study, corresponding flood inflow hydrographs were simulated and compared each other. Contrary to the case of peak rainfall intensity, difference in peak flow by both methods per each rainfall duration started to increase from about 12-hr duration. Especially, the difference in peak flow was significant when critical rainfall duration was considered, and this trend was similar for peak flows of other rainfall durations. Therefore, the method proposed in this study is thought to be the effective procedure for the construction of dimensionless cumulative rainfall curve that is representative of a basin while considering time distribution characteristics for different rainfall durations.

Analysis of Heat Dissipation Performance Based on Fluid Flow Patterns in a Liquid-Cooled Lithium-Ion Battery Module (수냉식 리튬이온 배터리 모듈의 유체 유동 패턴에 따른 방열 성능 분석)

  • Yong-Hyeon Kim;Jeong-Ho Shin;Eun-Ju Kim;Young-Chul Bae
    • The Journal of the Korea institute of electronic communication sciences
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    • v.19 no.5
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    • pp.875-882
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    • 2024
  • As the demand for high-capacity and high-output lithium-ion battery systems grows, the heat energy density within the battery also increases. This excess heat can shorten battery life and cause safety concerns, making the development of effective Battery Thermal Management Systems (BTMS) essential. In this study, we analyzed the temperature distribution and cooling performance of battery cells by applying various thicknesses of Baffle structures in a water-cooling system. The results show that the Baffle configuration affects the average temperature and temperature uniformity of the cells, leading to an optimal design that maximizes cooling performance.

Flow Characteristics for the Variation of Total Angles in Open Channel Bends (개수로 만곡부에서의 중심각 변화에 따른 흐름특성)

  • Lee, Jong Tae;Yoon, Sei Eui
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.3
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    • pp.195-202
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    • 1987
  • The flow characteristics in the shallow open channel bends are investigated, whose total angles were 30, 60, 90, 120, 150 and 180 in degree, and whose bed frictions were relatively rough(C=30) and smooth(C=60), respectively. The terms analyzed in this study are the water surface profile, the distribution of velocity and the flow direction, relating to the various total angles in the bends. The maximum depth in the bends could be found at the outside section of the location of $15^{\circ}$ local angle from the bend inlet, having no relation to the total angle and bed friction. It is supposed that the path of maximum velocities is especially influenced by the bottom friction when the total angles are bigger than 150 in degree, approximately. The ratio of the superelevation to the velocity head seems to increase as the total angle of the bends increases. The flow direction is skewed to the inner side at the bend inlet, and skewed to the outside at the bend outlet, regardless of their total angles.

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Effect of tip configuration of an oil fence on wake structure behind the fence (오일펜스의 tip 형상이 후류유동에 미치는 영향에 관한 연구)

  • Koh, Min-Seok;Lee, Sang-Joon;Lee, Choung-Mook;Chung, Sang-Kook
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.772-776
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    • 2001
  • The flow structures of turbulent shear layer behind oil fences with different tip configurations were investigated experimentally using flow visualization and PIV velocity field measurement. An oil fence was installed in a circulating water channel and the flow structure around the fence tip was mainly analyzed in this experiment. The four tip configurations tested in this experiment are knife edge; semi-circle edge, circular edge and rectangular edge. The 300 instantaneous velocity fields were measured using the single-frame PIV system and they were ensemble averaged to give the mean velocity field and spatial distribution of turbulent statistics. Free stream velocity was fixed at 10ms/sec and the corresponding Reynolds number based on the fence height was Re=4000. As a result, for the oil fence with rectangular edge, the streamwise velocity component was decreased. On the other hand it was increased for the oil fence with circular edge. For all four fences tested in this study, general flow pattern of the lower shear layer is analogous but the upper layer shows difference depending on the tip configurations. The oil fence with circular edge has more diffusive upper shear layer than that of the others. The shear layer of the oil fence with rectangular edge has relatively thin thickness. The oil fence with circular edge was found to be proper shape for tandem fence.

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Discharge Computation from Float Measurement in Vegetated Stream (부자 측정 시 식생을 고려한 유량산정에 관한 연구)

  • Lee, Tae Hee;Jung, Sung Won
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.2
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    • pp.307-316
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    • 2019
  • Development of vegetation in stream channel increases resistance to flow, resulting in increase in river stage upon flood and affecting change in stage-discharge relationship. Vegetation revealed in stream by water level reaching a peak and then declined upon flood is mostly found as prone. Taking an account of flow distribution with the number of vegetation, prone vegetation layer might be at height where discharge rate is zero (0) (Stephan and Guthnecht, 2002). However, there is a tendency that flow rate is overestimated when applying the height of river bed to flow area with no consideration of the height of vegetation layer in flow rate by float measurement. In this study, reliable flow measurement in stream with vegetation was calculated by measuring the height of vegetation layer after flood and excluding the vegetation layer-projected area from the flow area. The result showed the minimum 4.34 % to maximum 10.82 % of flow deviation depending on the scale of discharge. Accordingly, reliable velocity-area methods would be determined if vegetation layer-projected area in stream is considered in flow rate estimation using the flow area during the flood.

Design of a Prototype System for Graft-Taking Enhancement of Grafted Seedlings Using Artificial Lighting - Effect of air current speed on the distribution of air temperature and relative humidity in a graft-taking enhancement system (인공광을 이용한 접목표 활착촉진 시스템의 시작품 설계 - 활착촉진 시스템 내의 기온과 상대습도 분포에 미치는 기류속도의 효과)

  • 김용현
    • Journal of Biosystems Engineering
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    • v.25 no.3
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    • pp.213-220
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    • 2000
  • Grafting of fruit-bearing vegetables has been widely used to increase the resistance to soil-borne diseases, to increase the tolerance to low temperature or to soil salinity, to increase the plant vigor, and to extend the duration of economic harvest time. After grafting, it is important to control the environment around grafted seedlings for the robust joining of a scion and rootstock. Usually the shading materials and plastic films are used to keep the high relative humidity and low light intensity in greenhouse or tunnel. It is quite difficult to optimally control the environment for healing and acclimation of grafted seedlings under natural light. So the farmers or growers rely on their experience for the production of grafted seedling with high quality. If artificial light is used as a lighting source for graft-taking of grafted seedlings, the light intensity and photoperiod can be easily controlled. The purpose of this study was to develop a prototype system for the graft-taking enhancement of grafted seedlings using artificial lighting and to investigate the effect of air current speed on the distribution of air temperature and relative humidity in a graft-taking enhancement system. A prototype graft-taking system was consisted by polyurethane panels, air-conditioning unit, system controller and lighting unit. Three band fluorescent lamps (FL20SEX-D/18, Kumho Electric, Inc.) were used as a lighting source. Anemometer (Climomaster 6521, KANOMAX), T-type thermocouples and humidity sensors (CHS-UPS, TDK) were used to measure the air current speed, air temperature and relative humidity in a graft-taking system. In this system, air flow acted as a driving force for the diffusion of heat and water vapor. Air current speed, air temperature and relative humidity controlled by a programmable logic controller (UP750, Yokogawa Electric Co) and an inverter (MOSCON-G3, SAMSUNG) had an even distribution. Distribution of air temperature and relative humidity in a graft-taking enhancement system was fairly affected by air current speed. Air current speed higher than 0.1m/s was required to obtain the even distribution of environmental factors in this system. At low air current speed of 0.1m/s, the evapotranspiration rate of grafted seedlings would be suppressed and thus graft-taking would be enhanced. This system could be used to investigate the effects of air temperature, relative humidity, air current speed and light intensity on the evaportranspiration rate of grafted seedlings.

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Phosphorus Cycle in a Deep Reservoir in Asian Monsoon Are3 (Lake Soyang, Korea) and the Modeling with a 2-D Hydrodynamic Water Quality Model [CE-QUAL-W2] (아시아 몬순지역의 대형댐(소양호)에서의 인순환과 2차원모델의 적용)

  • Kim, Yoon-Hee;Kim, Bom-Chul
    • Korean Journal of Ecology and Environment
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    • v.37 no.2 s.107
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    • pp.205-212
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    • 2004
  • Phosphorus cycle was studied in a deep stratified reservoir in summer monsoon area (Lake Soyang, Korea) by surveying phosphorus input from the watershed and the movement of phosphorus within the reservoir. And the spatial and temporal distribution of phosphorus was modeled with a 2-dimensional water quality model (CE-QUAL-W2), Phosphorus loading was calculated by measuring TP in the main inflowing river (the Soyang River) accounting for 90% of watershed discharge. TP of the Soyang River showed a large daily variation with the flow rate. High phosphorus loading occurred during a few episodic storm runoff laden with suspended sediments and phosphorus. Because storm runoff water on rainy days have lower temperature, it plunges into a depth of same temperature (usually below 20m depth), forming an intermediate turbidity layer with a thickness of 20 ${\sim}$ 30 m. Because of stable thermal stratification in summer the intermediate layer water of high phosphorus content was discharged from the dam through a mid-depth outlet without diffusing into epilimnion. The movement of runoff water within the reservoir, and the subsequent distribution of phosphorus were well simulated by the water quality model showing a good accuracy. The major parameter for the calibration of phosphorus cycle was a settling velocity of detritus, which was calibrated to be 0.75 m ${\cdot}$ $day^{-1}$. It is concluded that the model can be a good simulator of limnological phenomena in reservoirs of summer monsoon area.

Multiphase Modeling on the Convective Transport of an Organic Solvent through Unsaturated Soils (비포화 토양층 내 유기 용매의 이류 이동에 대한 다상 모델링)

  • Lee Kun Sang
    • Journal of Soil and Groundwater Environment
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    • v.9 no.3
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    • pp.20-26
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    • 2004
  • In-situ photolysis is one of the most promising ways to clean up a soil contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). This study focuses on the mathematical description and model development of the convective upward transport of an organic solvent driven by evaporation and photodecomposition at the surface as the major transport mechanism in the clean up process. A finite-element-based numerical model was proposed to incorporate effects of multiphase flow on the distribution of each fluid, gravity as a driving force, and the use of van Genutchen equation for more accurate description of k-S-p relations. This paper presents results of extensive numerical calculations conducted to investigate the various parameters that play a role in the solvent migration through a laboratory-scale unsaturated soil column. The numerical results indicate that gravity affects significantly on the fluids distribution and evaporation for highly permeable soils. The soil texture has a profound influence on the fluid saturation profile during evaporation process. The amount of solvent convective motion increases with increasing evaporation rates and decreasing initial water saturation. Simulations conducted in this study have shown that the developed model is very useful in analyzing the effects of various parameters on the convective migration of an organic solvent in the soil environments.

Implementation of Semi-Automatic Intermittent Flow Type Hydroponics Smart Farm using Arduino (아두이노를 활용한 반자동 간헐흐름식 수경재배 스마트팜 구현)

  • Jang, Dong-Hwan;Kim, Dae-Hee;Lee, Sung-Jin;Moon, Sang-ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2021.10a
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    • pp.376-378
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    • 2021
  • According to the 2020 Global Climate Report released by the World Meteorological Organization, the average temperature of the Earth in 2019 was measured 1.1℃ higher on average than the temperature measured between 1850 and 1900 before industrialization. The change in average temperature affects the distribution of plants, and according to the vulnerability analysis paper, it can be seen that there is a change in the distribution area of plants when the average temperature rises. In this paper, to cope with these environmental changes, we propose a method of fabricating intermittent flow hydroponic smart farms using Arduino and sensors and controlling them through PCs and applications. The manufactured hydroponic smart farm identifies the farm's temperature and humidity, positive pH concentration, illumination, and water quality to check the amount of pumping, supplement LED control, sensor condition, overall management and cultivation of the farm, and grows in an appropriate environment.

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Effect of Marangoni Flow on Surface Roughness and Packing Density of Inkjet-printed Alumina Film by Modulating Ink Solvent System.

  • Oh, Yeon-Jun;Kim, Ji-Hoon;Yoon, Young-Joon;Yoon, Ho-Gyu;Kim, Jong-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.272-272
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    • 2010
  • We have fabricated alumina thick films by inkjet printing technology. Two different types of ink system were formulated in order to understand their evaporation behaviors and their evaporation effects on the powder distribution on, the surface during inkjet-printed alumina thick films. Single solvent system was formulated with N,N-dimethylformamide(DMF), which led to coffee ring effects which non-uniformly distributed alumina particles on the substrate during the ink evaporation. However, Co-solvent system which consists of both Water and DMF produced relatively uniform distribution of the particles on the substrate. We believe that these two different distributions of alumina particles are attributed to the ink fluid flow directions in the ink droplets ejected from the different ceramic ink system. We have modulated inkjet parameters such as dot-to-dot distance, line-to-line distance, jetting velocity and jetting drop size in order to find out the optimum condition for the printing of alumina thick films from two different ink systems. The surface roughness, microstructures and dielectric properties of these inkjet-printed alumina thick films were investigated.

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