• 지질공학
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• 제27권4호
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• pp.383-392
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• 2017

하천 인근에서 농경지 경작 및 생공용수 등의 이용을 위한 과도한 지하수의 취수는 하천수량 감소의 주요 원인으로 인식되고 있다. 따라서 수자원 관리에 있어서 하천 인근 지하수 관리는 매우 중요하며, 이를 위해서는 하천 인근 지하수 정보 파악이 우선되어야 한다. 본 연구에서는 하천으로부터의 이격거리에 따른 지하수 관정의 비율과 하천 인근에 포함된 관정의 분포 특성을 파악하기 위해 안성천 유역을 대상으로 지하수 취수계획량 현황을 조사하였다. 안성천 수계 전체 관정 중 하천 인근에 포함된 허가관정의 취수계획량 비율은 20.6%, 하천 인근에 포함된 신고관정의 경우는 31.3%로 나타났다. 하지만 하천 인근 관정의 전체 취수계획량 중 허가관정은 11.4%, 신고관정은 88.6%에 해당하는 것으로 나타나 하천인근에서 신고관정의 취수비율이 월등히 높은 것으로 분석되었다. 현재까지는 지하수법에 의해 하천 인근 지하수 개발시 단지 허가관정에 대해서만 의무적으로 지하수영향조사서를 작성하도록 되어있으나 하천 인근의 이용관정 중 신고관정의 양이 훨씬 많은 것을 감안하면 신고관정에 대한 적극적이면서도 신중한 관리가 필요할 것으로 판단된다.

• 한국수자원학회논문집
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• 제47권8호
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• pp.685-691
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• 2014

강변여과는 하천 인근에 다수의 관정을 설치하여 하천수의 수질 개선을 추구하는 기술이다. 그런데 다수의 관정이 인접해 있는 경우 관정간의 상호간섭 현상으로 인하여 취수량에 영향을 미친다. 강변 여과 관정의 경우에는 관정이 관망으로 연결되기 때문에 간섭효과의 요인에는 지하수위 강하량 외에도 유량변화에 따른 관망 수두손실이 포함된다. 간섭효과는 취수정으로 유입되는 하천수와 배후 지하수의 비율에도 영향을 미친다. 본 연구에서는 강변여과시스템의 대수층과 관망흐름을 통합해석하는 기법을 이용하여 복수 관정의 간섭효과와 하천수 비율을 산정하는 방법을 제시하고 실제에 가까운 가상의 강변여과시스템에 적용하였다. 관정 가동 패턴에 따라 취수량은 5% 이상 차이가나고 배후지하수 유입비율도 30~40% 범위로 10% 이상 차이가 날 수 있는 것으로 나타났다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.905-913
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• 2008

The water resource depending on mostly surface water has many problems, such as contaminated and unpredicted contamination event. For this reason, it has been employed highly technical treatment method for them, such as ground water dam and river bank filtration. it has been developed the radial collector wells in kind of bank filtration to increase efficiency for in-taking the water resource insead of the vertical well needed many wells to take more resource. But it has many problems with the incumbent method to bore the horizontal hole for radial collector wells, such as filling with the filter material outside of a strainer by watering, jamming as retrieving the casing tube with the filter material, eccentric boring etc. To reduce the problems of incumbent equipment, it has been developed the horizontal boring equipment and performed the field trial tests several times, which have bits and water jetting system with rotating the cone-shaped front to be excavated easily. In this paper, it was compared the brand-new with the incumbent non-rotating pressing insertion method. Also it was shown the problems of the incumbent method was reduced effectively.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권5호
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• pp.456-465
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• 2016

In order to optimize the performance of a Wells turbine with fixed guide vanes, the designs of an end plate and a ring on the tip of the turbine rotor are proposed as penetrating blade tip treatments. In this study, numerical investigations are made using computational fluid dynamics (CFD)-based ANSYS Fluent software, and validated by corresponding experimental data. The flow fields are analyzed and non-dimensional coefficients $C_A$, $C_T$ and ${\eta}$ are calculated under steady-state conditions. Numerical results show that the stalling phenomenon on a ring-type Wells turbine occurs at a flow coefficient of ${\phi}=0.36$, and its peak efficiency can reach 0.54, which is 16% higher than that of an unmodified turbine and 9% higher than in the case of an endplate-type turbine. In addition, quasi-steady analysis is used to calculate the mean efficiency and output work of a wave cycle under sinusoidal flow conditions. As a result, it has been found that the ring-type turbine is superior to other types of Wells turbines.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.113-114
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• 2004

In order to classify the groundwater recharge characteristics in an urban area, a time series analysis of groundwater level data was performed. For this study, the daily groundwater level data from 35 monitoring wells were collected for 3 years (Fig. 1). The use of the cross-correlation function (CCF), one of the time series analysis, showed both the close relationship between rainfall and groundwater level change and the lag time (delay time) of groundwater level fluctuation after a rainfall event. Based on the result of CCF, monitored wells were classified into two major groups. Group I wells (n=10) showed a fast response of groundwater level change to rainfall event, with a delay time of maximum correlation between rainfall and groundwater level near 1 to 7 days. On the other hand, the delay time of 17-68 days was observed from Group II wells (n=25) (Fig. 1). The fast response in Group I wells is possibly caused by the change of hydraulic pressure of bedrock aquifer due to the rainfall recharge, rather than the direct response to rainfall recharge.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.225-228
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• 2003

For the purpose of finding out the distributions of groundwater uses, the effect of facilities on the parameter and the correlations among measurements, various statistical analysis were carried out with the data of groundwater quality measurements from January to December in 2002. 1. The rates of groundwater for drinking water were 10.5% in Yangcheon-Gu, 10.2% in Kangdong-Gu, and 9.9% in Eunpyung-Gu. The rates of other uses of groundwater were shown to be 58.1%(786 wells) for civil defense emergency, 22.1%(299 wells) for contamination-concerning, 9.8%(133 wells) for water quality monitoring, consisting of 90% of all groundwater. 2. The 52.6% of groundwater for drinking were demonstrated to be appropriate while 91.9% for tither uses-domestic, industrial, agricultural uses- were shown to be proper. 3. For drinking water, the average values of colar, turbidity, NH3-N, F, and Fe were 11.216 degree, 2.138 NTU, 2.458mg/l, 0.212mg/1 and 0.507mg/1 respectively. 4. In cases of drinking water wells for emergency, the results of statistical analysis showed that building year of the wells, depth and pumping rate didn't affect on whether it was proper for that use or not. It were shown that there were linear correlations between depth and NO$_3$-N(-0.171) and F￣(0.332) while the correlation coefficients were 0.381 and -0.169 between the building year of well and depth and pumping rate respectively.

• 한국태양에너지학회 논문집
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• 제23권2호
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• pp.99-105
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• 2003

This paper presents the effect of rotor geometry on the performance of a small-scale Wells turbine for wave energy conversion. In this study, four kinds the Wells turbine of blade profile were selected from previous studies. The types of blade profile included in the papers are as follows: NACA0020 ; NACA0015; CA9; and HSIM 15-262123-1576. The experimental investigations have been performed for two solidities by testing model under steady flow conditions. The effect of blade profile on the running and starting characteristics under sinusoidal flow conditions have also been investigated by a numerical simulation based on a quasi-steady analysis. In addition, the effect of sweep on the turbine characteristics has been studied for the cases of CA9 and HSIM 15-262123-1576. Based on the evaluation, a suitable choice of these design factors has been suggested. As a result, it seems that a suitable choice of the sweep ratio of 0.35 for the blade profile of the Wells turbine.

• Ocean and Polar Research
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• 제43권4호
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• pp.295-306
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• 2021

A field scale productivity analysis is required for the development of gas hydrate in marine sedimentary layers to verify the field applicability of production techniques and to improve productivity. In this study, the productivity resulting from the application of depressurization using multi-wells for the development of gas hydrate in the Ulleung Basin, East Sea of Korea, was determined. A numerical analysis model reflecting the conditions of candidate sites for the Ulleung Basin was constructed, and the productivity and dissociation behavior were comparatively analyzed. The pressure propagation and gas hydrate dissociation region by the multi-wells were wider and the productivity was higher than that of a single well. Different depressurization effects according to the spacing of multi-wells affected productivity. The results provide basic data for productivity analysis when establishing a field test production plan for the Ulleung Basin.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권3호
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• pp.1-10
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• 2022

Most wells developed in Jeju island before the enactment of the Groundwater Management Ordinance in 2002 are vulnerable to aquifer contamination due to inflow of upper groundwater having the high concentration of nitrate nitrogen, likely due to incomplete grouting in upper section of the wells. Although these wells require entire reinstallation, it is often necessary to rehabilitate the existing wells due to various constraints. Therefore, to identified the inflow section of contaminants, the thermal level sensor (TLS) technique was firstly applied for three wells, which enables to monitor temperature variations in every 50 cm depth. Then, the grouting material was injected to the upper section to prevent the inflow of upper contaminated groundwater into the entire aquifer. By applying TLS technique, it was found that the temperature deviations in the upper groundwater inflow section decreased sharply. Moreover, both the change in the concentration of nitrate nitrogen in the rainy/dry seasons and the average concentrations were found to decrease rapidly after grouting material injection. Consequently, the application of TLS proposed in the study turned out to be appropriate to prevent aquifer contamination.

• 한국농공학회논문집
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• 제64권6호
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• pp.13-23
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• 2022

The purpose of this study was to analyze the impact of greenhouse cultivation area and groundwater level changes due to the water curtain cultivation in the greenhouse complexes, which are mainly situated along rivers where water resources are easy to secure. The groundwater observation network in Miryang, Gyeongsangnam-do, located downstream of the Nakdong River, was selected for the study area. We classified the groundwater monitoring well into the greenhouse (riverside) and field cultivation areas (plain and mountain) to compare the groundwater impact of water curtain cultivation in the greenhouse complex. The characteristics of groundwater level changes classified by terrain type were analyzed using the observed data. Riverside wells have significant permeability coefficients and are close to rivers, so they are greatly affected by river flow and precipitation changes so that water level shows a specific pattern of annual changes. Most plain wells do not show a constant annual change, but observation wells near small rivers and small-scale greenhouse cultivation areas sometimes show annual and daily changes in which the water level drops during winter. Compared to other observation wells, mountain wells do not show significant yearly changes in water level and show general characteristics of bedrock aquifer well with a low permeability coefficient.