• 한국농공학회지
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• 제41권5호
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• pp.77-85
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• 1999

Irrigation pipeline systems have been recently adopted for irrigation purposes, which was thought to improve irrigation efficiencies. However, if hydraulic characteristics are not evaluated in designing , overpressure due to waterhammer may occur and result in serious problems. Therefore, in this study a model was formulated to simulate unsteady motion of water in a pipeline resulting from valve closure, the applicability of the model owas tested with fiedld data, and the results showed good agreement in maximum piezometric head. Also, simulated maximum piezometric head was compared with designed piezometric head computed by empirical method, and maximum piezometric head in a pipeline resulting from valve closure was simulated and analyzed with varing surge tank's position and diameter.

• 지질공학
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• 제17권2호
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• pp.177-185
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• 2007

우리나라 대부분의 온천은 자연용출된 온천수를 사용하는 것이 아니라 시추공 내에서 수중펌프로 양수하여 사용하고 있다. 따라서 양수량에 따라 피압수두가 하강되어 있으며, 이 논문에서는 온양온천지구를 대상으로 양수량과 수위강하의 관계를 해석하고자 하였다. 온양온천지구 내에는 38개 공이 시추되어 있으며, 그 심도는 약 124-303 m이다. 이들 중 4개 관측공을 이용하여 피압수두를 관측하였으며, 관측 간격은 매 1-10분 간격으로 약 10개월간 관측하였다. 피압수두의 변화 양상은 성수기와 비수기에 따라 1년 주기로 사인곡선(sine curve)을 보이고 있으며, 그 값은 지표로부터 약 98-139m 정도이다. 이때 양수량은 $2,300-4,800m^3/day$로 앙수량의 변화에 따라 수위강하가 변하고 있다. 따라서 각 수위강하에 대한 양수량의 관계를 해석하여 관계식을 도출하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.445-448
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• 2007

Three boreholes (BE-1, BE-2 and BE-3) were drilled for geothermal resources development in Haengbok (Sejong) city. Monitoring of temperature, electric conductivity (EC) and piezometric head were carried out at each borehole. Temperatures were measured at 10 m depth, it ranges from 13.22$^{\cdot}C$ to 14.4$^{\cdot}C$. EC of BE-1 and BE-3 declined with time because groundwater flowed in boreholes. Barometric efficiency was analysed by piezometric head of groundwater and atmospheric pressure, it ranges from 44.8% to 71.5%. These parameters can be used for a geothermal modeling.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.438-441
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• 2006

The groundwater level was originally above the surface at the Onyang spa area. However, it is now 98-138m depth below the surface deu to the artificial pumping from boreholes. The fluctuations of the piezometric head were observed in 4 boreholes. Transmissivity estimated from the pumping rate and the drawdown is about $577.51 m^2/day$ The transmissivity of Onyang spa area is much larger than common values of fractured aqui for the drawdown of the piezometric head by artificial pumping is widely spreaded out in that area. The drawdown related to each pumping rate was analyzed and the formula between drawdown and pumping rate was made by a regression analysis. The formula can be applied for the condition of enough groundwater flowing into the Onyang spa area

• 한국토양비료학회지
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• 제14권4호
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• pp.185-189
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• 1982

습답(濕畓)의 저수요인(低收要因)을 구명(究明)하기 위(爲)하여 수분이동(水分移動) 방향(方向), 토양온도(土壤溫度) 및 산화환원전위(酸化還元電位)와 수도(水稻)의 생육(生育)과의 관계(關係)를 조사(調査)한 결과(結果)는 다음과 같다. 1. 곡간습답(谷間濕畓)에서는 지점(地点)에 따라 ${\Delta}Hp$의 변이(變異)가 크고 수도(水稻)의 작황(作況)도 차이(差異)가 심(甚)하였으나 평탄습답(平坦濕畓)에서는 지점간(地点間)의 ${\Delta}Hp$가 거의 균일(均一)하였다. 2. 물의 이동(移動) 방향(方向)에 따라 토양온도(土壤溫度) 및 수도생육(水稻生育)의 차이(差異)가 뚜렷하게 나타났다. 3. ${\Delta}Hp$와 수도생육(水稻生育) 및 수량간(收量間)에는 부(負)의 상관(相關)이 있어 지하수(地下水) 용출(湧出)이 많을수록 수량(收量) 감소(減少)가 심(甚)하였다. 4. 토양온도(土壤溫度)와 수도(水稻) 생육(生育) 및 수량(收量) 간(間)에는 정(正)의 상관(相關)이 있었으며, $16^{\circ}C$로 유지(維持)된 지점(地点)에서는 생육(生育)이 정지(停止)되어 수량(收量)이 전혀 없었다. 5. 토양(土壤)의 산화환원전위(酸化還元電位)는 ${\Delta}Hp$가 0의 부근(部近)에서 낮았고 물의 이동(移動)이 심(甚)한 곳에서는 높았다.

• Current Research on Agriculture and Life Sciences
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• 제3권
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• pp.44-54
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• 1985

In order to determine the critical head values of boiling and piping, several experiments were performed for 3 cases of model dykes on 7 kinds of pervious foundations. The results obtained are as follows : 1. It appears that the coarser and the denser the foundation material, the higher the critical heads of boiling and piping, and that the lower the permeability of the foundation, the higher the critical heads of boiling and piping. 2. A difference in head between the moments of boiling and piping is greater in the case 2 or case 3 than in the case 1 because of the additional hydraulic resistance. And it is found that the coarser the foundation material, the greater the head difference. 3. The critical heads of boiling and piping is directly prortional to the seepage length. 4. The piezometric heads close to the singular point are of the same magnitude, provided that the geometry of the model dyke and foundation material are the same. 5. Variations of the weight of model dyke can not affect the critical head. According to the conclusions shown above, the critical head of piping can be more practically predicted for prototype using the results from laboratory tests on scale model.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.806-813
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• 2008

In this research, mainly research about the structural and functional stability of sea dyke with variation of seepage condition after final closure. The piezometric head (water head in embankment) monitoring system was installed at two representative final closure section. The dredged fine sand filling condition was evaluated by in-situ test results. Also, the numerical analysis was performed to determine the permeability of bottom protection layer filled with dredged fine sand by monitoring results. According to numerical back analysis results, the coefficient of permeability of bottom protection section of is $7.6{\times}10^{-6}$ m/sec. These results are noted that the bottom protection layer of sea dyke was strong and intensively filled with dredged sand. Also, based on the seepage analysis, the seepage flux of this sea dyke was calculated about $2.42m^3$/day/m which is 29% decreased value compare with adjacent sea dyke.

• 한국농공학회지
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• 제43권2호
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• pp.59-68
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• 2001

A water balance analysis was performed for a paddy field neighboring the Dongchang stream, downstream of the Unmun reservoir, which is constructed for the urban water supply. Daily rainfall data were collected and irrigation water flow rate, drainage flow rate, evaportranspiration, infiltration, and piezometeric head were measured in the field. The flow rates were continuously observed by water level logger during the growing season. The evaportranspiration and the infiltration were measured by N-type depletion meter and cylindrical infiltrometer, respectively. PVC pipes with 12mm diameter were used for piezometric head measurement. Total Irrigation and drainage flows were 3,608mm and 1,170mm in 1999, and 3,971mm and 1,548mm in 2000, respectively. The mean and range of the daily infiltration rate were 4.4mm/d and 3.4mm/d to 5.5mm/d in 1999 and 5.1mm/d and 4.1mm/d to 6.5mm/d in 2000, respectively. The net ground water flow including the change of soil water storage was 2,855mm in 1999 and 2,540mm in 2000. The evapotranspiration was 458.3mm in 1999 and 553.5mm in 2000. The range of daily evapotranspiration rate was from 1.6 to 8.7mm/d. The return flow ratio was about 32% in 1999 and 39% in 2000 and three year average was 35% including previous study in 1997. The amount of irrigation water was much higher than design standards or references in this study, This was caused by the inadequate water management practice in the area where water was oversupplied on farmers’ request rather than following sound water management principles.

• Geomechanics and Engineering
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• 제27권5호
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• pp.433-445
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• 2021

Artificial ground freezing (AGF) is a commonly used geotechnical support technique that can be applied in any soil type and has low environmental impact. Experimental and numerical investigations have been conducted to optimize AGF for application in diverse scenarios. Precise simulation of groundwater flow is crucial to improving the reliability these investigations' results. Previous experimental research has mostly considered horizontal seepage flow, which does not allow accurate calculation of the groundwater flow velocity due to spatial variation of the piezometric head. This study adopted vertical seepage flow-which can maintain a constant cross-sectional area-to eliminate the limitations of using horizontal seepage flow. The closure time is a measure of the time taken for an impermeable layer to begin to form, this being the time for a frozen soil-ice wall to start forming adjacent to the freeze pipes; this is of great importance to applied AGF. This study reports verification of the reliability of our experimental apparatus and measurement system using only water, because temperature data could be measured while freezing was observed visually. Subsequent experimental AFG tests with saturated sandy soil were also performed. From the experimental results, a method of estimating closure time is proposed using the inflection point in the thermal conductivity difference between pore water and pore ice. It is expected that this estimation method will be highly applicable in the field. A further parametric study assessed factors influencing the closure time using a two-dimensional coupled thermo-hydraulic numerical analysis model that can simulate the AGF of saturated sandy soil considering groundwater flow. It shows that the closure time is affected by factors such as hydraulic gradient, unfrozen permeability, particle thermal conductivity, and freezing temperature. Among these factors, changes in the unfrozen permeability and particle thermal conductivity have less effect on the formation of frozen soil-ice walls when the freezing temperature is sufficiently low.