• 농촌계획
• /
• 제6권2호
• /
• pp.73-81
• /
• 2000

This study was carried out to measure the amount of outlet discharge and analyse the water quality from an agricultural reservoir. Joongpyong reservoir was selected as the monitoring site. Daily discharge was determined by measured water level data of delivery canal and the stage-discharge relation curve. The measured water discharge through culvert outlet of Joongpyong reservoir was 593,200m3 which was equivalent to irrigation depth 1,186mm during irrigation period in 1999. And water samples were taken from the surface water of reservoir and delivery canal, periodically. Temporal variation of water quality constituents such as water temperature, pH, EC, total nitrogen, total phosphorus were investigated. The result showed that pH was ranged 6.9 7.8, total nitrogen 1.39 4.11mg/L, total phosphorus 0.007 0.036 mg/L, respectively.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2005년도 학술발표회(2)
• /
• pp.1453-1454
• /
• 2005

• 한국정밀공학회지
• /
• 제23권3호
• /
• pp.69-75
• /
• 2006

In this paper, micro electrical discharge milling using deionized water as dielectric fluid was investigated. In EDM, dielectric fluid is an important factor which affects machining characteristics. When deionized water was used as dielectric fluid, machining characteristics were investigated according to voltage, capacitance, and resistivity of deionized water. Machining gap increased with increasing voltage and capacitance. As the resistivity of deionized water decreased, the machining gap increased. The wear of a tool electrode and machining time can be reduced by using deionized water instead of EDM oil. Surface roughness was also improved when deionized water was used.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
• /
• pp.15-18
• /
• 2003

In this paper, We explained the best shape design of electrode for discharge on the water. Electrode with rounding was reduced maximum electric field of over 40% to electrode without rounding for discharge on the water and the best shape of electrode for discharge on the water designed when shape of electrode had a curve radius of over $60^{\circ}$ at electrode's face to electrode's face with minimum distance and a curve radius of under $120^{\circ}$ at electrode's side face to electrode's front face. And When dielectric beads are used between electrodes, the life of electrodes is improved by lower stress of electric field on surface of electrodes.

• Nuclear Engineering and Technology
• /
• 제52권10호
• /
• pp.2204-2220
• /
• 2020

An open-pool type research reactor is designed and operated considering the accessibility around the pool top area to enhance the reactor utilization. The reactor structure assembly is placed at the bottom of the pool and filled with water as a primary coolant for the core cooling and radiation shielding. Most radioactive materials are generated from the fuel assemblies in the reactor core and circulated with the primary coolant. If the primary coolant goes up to the pool surface, the radiation level increases around the working area near the top of the pool. Hence, the hot water layer is designed and formed at the upper part of the pool to suppress the rising of the primary coolant to the pool surface. The temperature gradient is established from the hot water layer to the primary coolant. As this temperature gradient suppresses the circulation of the primary coolant at the upper region of the pool, the radioactive primary coolant rising up directly to the pool surface is minimized. Water mixing between these layers is reduced because the hot water layer is formed above the primary coolant with a higher temperature. The radiation level above the pool surface area is maintained as low as reasonably achievable since the radioactive materials in the primary coolant are trapped under the hot water layer. The key to maintaining the stable hot water layer and keeping the radiation level low on the pool surface is to have a stable flow of the primary coolant. In the research reactor with a downward core flow, the primary coolant is dumped into the reactor pool and goes to the reactor core through the flow guide structure. Flow fields of the primary coolant at the lower region of the reactor pool are largely affected by the dumped primary coolant. Simple, circular, and duct type discharge headers are designed to control the flow fields and make the primary coolant flow stable in the reactor pool. In this research, flow fields of the primary coolant and hot water layer are numerically simulated in the reactor pool. The heat transfer rate, temperature, and velocity fields are taken into consideration to determine the formation of the stable hot water layer and primary coolant flow. The bulk Richardson number is used to evaluate the stability of the flow field. A duct type discharge header is finally chosen to dump the primary coolant into the reactor pool. The bulk Richardson number should be higher than 2.7 and the temperature of the hot water layer should be 1 ℃ higher than the temperature of the primary coolant to maintain the stability of the stratified thermal layer.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2016년도 학술발표회
• /
• pp.196-196
• /
• 2016

Landslide dam failure presents as a severe natural disaster due to its adverse impact to people and property. If the landslide dams failed, the discharge of a huge volume of both water and sediment could result in a catastrophic flood in the downstream area. In most of previous studies, breaching process used to be considered as a constructed dam, rather than as a landslide dam. Their erosion rate was assumed to relate to discharge by a sediment transport equation. However, during surface erosion of landslide dam, the sediment transportation regime is greatly dependent on the slope surface and the sediment concentration in the flow. This study aims to accurately simulate the outflow hydrograph caused by landslide dam by overtopping through a 2D surface flow erosion/deposition model. The lateral erosion velocity in this model was presented as a function of the shear stress on the side wall. The simulated results were then compared and it was coherent with the results obtained from the experiments.

• Ocean and Polar Research
• /
• 제26권1호
• /
• pp.33-42
• /
• 2004

Effect of freshwater discharge on the long-term salt balance in the Northern and Central Indian River Lagoon (IRL) is successfully simulated by a new analytical solution to a water balance-based one-dimensional salt conservation equation. Sensitivity tests show that the salinity levels drop abruptly even during the dry season (November to May) due to the high surface runoff discharge caused by tropical storms, depressions, and passage of cold fronts. Increasing surface runoff and direct precipitation has risen by ten times, lowering the salinity level down to 12psu in the Northern Central zone, and to 17 psu in the Northern zone. However, the salinity level in the Southern Central zone has decreased to 25 psu. High sensitivity of the Northern Central zone to freshwater discharge can be partially explained by a rapid urbanization in this zone. During the dry season, less sensitivity of the Southern Central zone to the increased surface runoff is attributed to the proximity of the zone to the Sebastian Inlet and a strong diffusion condition possibly resulting from the seawater intrusion to the surficial aquifer at the Vero Beach. During the wet season, however, the whole study area is highly sensitive to freshwater discharge due to the weak diffusion conditions. High sensitivity of the IRL to the given diffusion conditions guarantees that the fresh-water release occurs during strong wind conditions, achieving both flood control in the drainage basin and a proper salinity regime in the IRL.

• 대한환경공학회지
• /
• 제30권5호
• /
• pp.567-573
• /
• 2008

달천의 하도내에서 종횡단의 수질조사 및 하천특성에 대한 분석을 수행하였으며, 주요 지점을 중심으로 유량변화에 따른 수질변화를 검토하였다. 강우의 발생으로 유량이 증가한 경우에 BOD의 농도는 감소하였으며, TN과 TP의 농도는 증가한 것으로 나타났다. 유량이 증가하였던 Case 2에서 BOD, TN, TP는 모두 유속과 수심에 대하여 큰 상관계수를 보였다. 강우가 비점오염원의 유입을 유도하여 하도내 수질변화에 많은 영향을 미치고 있는 것으로 분석되었다. 하도내의 유속은 수치모형(SMS)을 통해서 분석할 수 있었으며, 경사가 크고, 하도의 폭이 좁은 상류 구간에서 비교적 유속이 큰 것으로 나타났다. 2차원 하도내에서 오염원의 거동특성이 모의되었으며, 주수로인 흐름의 중앙부분으로 오염원이 빠르게 확산되는 것으로 나타났다. 오염 확산은 흐름에 큰 영향을 받고 있는 것으로 모의되었다.

• 물과 미래
• /
• 제23권4호
• /
• pp.445-457
• /
• 1990

난류 및 부력효과가 강한 온배수 확산을 예측하기 위하여 난류모델을 이용한 수치모델의 개발이 두드러지고 있다. 본 연구는 정지수역으로 유입하는 온배수 수치모델을 개발하였다. Reynolds 응력항 및 난류 열 프럭스항의 처리를 위하여 k-$\varepsilon$난류모델에 온도자승유동항과 이의 감쇄율 전달방정식을 추가한 4-방정식 난류모델을 이용하였다. 지배방정식을 부분적인 포물형태의 전환을 통한 수치해석이 이용되었다. 계산결과는 Pande 등의 실험결과와 비교적 잘 일치하였고, McGuirk 등의 2-방정식 난류모델에 의한 해석결과와 비교분석하였다. 아울러 고리 원자력 1호기에의 적용을 통하여 본 모델의 실용성 및 타당성 입증하였다.

• 에너지공학
• /
• 제5권2호
• /
• pp.198-202
• /
• 1996

Reactive metals like aluminum generate hydrogen gas when it reacts with water. Aluminum, despite its high chemical affinity with water, cannot continue the reaction due to the passive oxide layers formed on its surface. When the reaction is assisted by electrical energy dissipation in the form of discharge, the reaction is more likely to be sustained. In this report, some preliminary experimental results are presented regarding the hydrogen generation based on this scheme.