• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.961-966
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• 2001

The Wells turbine is one of the simplest and most promising self-rectifying air turbines which are useful for the systems of alternative energy development in near future, and it is economically desirable from the point of view of the practical use, as well. To investigate the effect of blade sweep on the performance of the Wells turbine, computations of a fully 3-D Navier-Stokes are carried out under steady flow conditions of NACA0020 blade. It is known that the performance of the Wells turbine is considerably influenced by the blade sweep. An optimum blade sweep ratio(f=0.35) for the NACA0020 is found to be the most promising for the practical use, and this value is in good agreement with the previous experiments. It is also found that the overall turbine performance for the NACA0020 is better than that for the CA9.

• 한국태양에너지학회 논문집
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• 제25권3호
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• pp.61-67
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• 2005

In order to improve the stall characteristics of the Wells turbine blade, experimental investigations have been made in the performance of the Wells turbine with 1), 2) grooved blade surface to reduce fraction drag against the steady and the sinusoidal flow condition. As the conclusion, the two methods are valid to improve the stall characteristics of the Wells turbine.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.511-514
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• 2003

Nowadays, wells tapping the deep aquifers become general because water quality of the shallow groundwater has been gradually degraded over the last 30 years as a result of rapid industrialization and intensive agricultural activities. However, many of the deep wells also suffer problems of water-quality degradation in several years after the well installation, nevertheless those were properly completed and managed. It is believed that the heavy pumping from deep wells causes the doward movement of the contaminated, shallow groundwaters and introduces them into the deep aquifers. In this study, we introduces a shallow capture well system, which could effectively prevent the shallow groundwaters of poor water duality from moving into the deep aquifers by pumping of deep production wells. Even though additional costs are required to apply this system, we believe that this method could be appropriate for the deep wells that are important for the public health.

• 한국환경보건학회지
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• 제1권1호
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• pp.36-40
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• 1974

A Study on environmental sanitation on the well in Seoul was made to find the degree of Physio-chemical and Bacterial contamination. For this study 30 wells were located at Nokbundong Hongjaidong and Hongeundong from September 13 to 22 1971. As the results of this study the following conclusions were obtained. 1) Seventy per cent were being utilizing by from 10 to 50 households per well. 2) About 93 per cent of the wells were found to be dug out in Rocks. 3) Eighty-three per cent of the wells surveyed in the slums had a depth of water shorter than 20 cm. 4) The degree of Total Viable Bacteria contamination were high point $15{\times}10^2$ low point 13 and coliform bacteria were high point $79{\times}10^1$ low point 1 organism per ml. 5) Only 4 wells (13.3%) were able to drink but 26 wells (86.7%) were not drinking by physio-chemical and Bacterial contamination.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.3-12
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• 2003

This paper reviews the present state of the art on the self-rectifying air turbines, which could be used for wave energy conversion. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been evaluated numerically and compared from the viewpoints of the starting and running characteristics. The types of turbine included in the paper are as follows: (a) Wells turbine with guide vanes (WTGV); (b) turbine with self-pitch-controlled blades (TSCB); (c) biplane Wells turbine with guide vanes (BWGV); (d) impulse turbine with self-pitch-controlled guide vanes (ISGV) and (e) impulse turbine with fixed guide vanes (IFGV). As a result, under irregular wave conditions it is found that the running and starting characteristics of the impulse type turbines could be superior to those of the Wells turbine. Moreover, the authors have explained the mechanism of hysteretic behavior of the Wells turbine and the necessity of links for improvement of the performance of ISGV.

• 한국지하수토양환경학회지:지하수토양환경
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• 제25권2호
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• pp.1-8
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• 2020

In general, the estimation of optimum yield for the radial collector well is determined by the empirical equation or numerical modeling, in which hydraulic conductivity of the aquifer is a main influence factor. Hydraulic conductivities of 164 soil samples collected from boreholes and horizontal wells (average length: about 50 m) installed during well construction in the Anseong stream were drawn in two-dimensional map by the Kriging method and utilized in this study. Hydraulic conductivity analyses by Representative Elementary Count (REC) indicated the average hydraulic conductivity is similar to that of the pumping test when the number of samples reaches about 1,000, which correspond to 1,000 ㎡. Pumping test was also conducted at 1 pumping well and 13 observation wells to estimate hydraulic conductivities at each observation well. REC analysis indicated that the average value of hydraulic conductivity calculated from at least four observation wells is valid as a representative value. The overall result suggested that multiple observation wells or multiple pumping-observation well systems that are located within the range of horizontal wells should be utilized to properly estimate the representative hydraulic conductivity values and the yield of a radial collector well.

• 한국지하수토양환경학회지:지하수토양환경
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• 제19권3호
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• pp.66-81
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• 2014

A Fortran program was developed to determine the optimal locations of an artificial recharge well. Three objective functions were considered: (1) maximizing the recovery rates, (2) maximizing the injection rates, and (3) minimizing the coefficient of variation of the increased pumping rates. We also suggested a new aggregate objective function which combined the first and the third objective functions. The model results showed that locating the injection well inside the cluster of pumping wells was desirable if either the recovery or the injection rate was taken into account. However, the injection well located outside the cluster evenly increased the pumping rates in existing pumping wells. Therefore, for clustered pumping wells, installing an injection well at the center or the upstream of the pumping wells seems beneficial. For linear arrangement of pumping wells parallel to the constant head boundary, locating the injection well in the upstream was recommended. On the contrary, in case of the linear arrangement perpendicular to the constant head boundary, the injection well installed on both sides of the central part of the pumping wells was preferable.

• 자원환경지질
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• 제47권3호
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• pp.219-225
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• 2014

전국의 지하수 관정은 2012년 기준 1,474 천 개소이며 지하수 이용량이 총 용수 이용량의 12%를 차지하고 있다. 수자원장기기본계획은 2021년 전국 용수 수요가 공급을 초과할 것으로 전망하고 있어 지하수 이용이 더욱 중요한 과제가 되고 있다. 우리나라는 지하수 활용을 위한 인공함양이나 강변여과 보다 관정에 크게 의존하고 있으므로 관정의 경제성에 대한 평가가 우선적으로 이루어져야 할 것이다. 따라서 본 논문은 관정에 의한 지하수자원 활용이 경제적인지 아닌지를 분석하는 것에 목적을 둔다. 관정의 편익은 크게 3가지로 나누어 첫째, 활용가치로 음용수 및 농공용수의 공급가치, 둘째 비활용 가치로 잠재활용 대비 미래를 위한 부존가치를 포함하고 있다. 또한 비용은 관정의 설치비용 및 교체비용, 관리비용, 그리고 폐공의 환경오염 비용 등을 모두 포함한다. KDI의 수자원사업 예비타당성 가이드라인과 미국 환경청 그리고 세계은행의 지하수자원 비용-편익분석 모델을 원용하여 관정의 비용편익 비율을 계산하였다. 그 결과 지하수 관정의 편익이 비용보다 2.98배 높아 지하수 관정에 의한 지하수자원 공급이 경제성이 있는 것으로 나타났다.

• 한국지구과학회지
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• 제43권4호
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• pp.539-556
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• 2022

In the coastal areas of Jeju Island, composed of volcanic rocks, saltwater intrusion occurs due to excessive pumping and geological characteristics. Groundwater level and electrical conductivity (EC) in multi-depth monitoring wells in coastal areas were characterized from 2005 to 2019. During the period of the lowest monthly precipitation, from November 2017 until February 2018, groundwater level decreased by 0.32-0.91 m. During the period of the highest monthly precipitation, from September 2019 until October 2019, groundwater level increased by 0.46-2.95 m. Groundwater level fluctuation between the dry and wet seasons ranged from 0.79 to 3.73 m (average 1.82 m) in the eastern area, from 0.47 to 6.57 m (average 2.55 m) in the western area, from 0.77 to 8.59 m (average 3.53 m) in the southern area, and from 1.06 to 12.36 m (average 5.92 m) in the northern area. In 2013, when the area experienced decreased annual precipitation, at some monitoring wells in the western area, the groundwater level decreased due to excessive groundwater pumping and saltwater intrusion. Based on EC values of 10,000 ㎲/cm or more, saltwater intrusion from the coastline was 10.2 km in the eastern area, 4.1 km in the western area, 5.8 km in the southern area, and 5.7 km in the northern area. Autocorrelation analysis of groundwater level revealed that the arithmetic mean of delay time was 0.43 months in the eastern area, 0.87 months in the northern area, 10.93 months in the southern area, and 17.02 months in the western area. Although a few monitoring wells were strongly influenced by nearby pumping wells, the cross-correlation function of the groundwater level was the highest with precipitation in most wells. The seasonal autoregressive integrated moving average model indicated that the groundwater level will decrease in most wells in the western area and decrease or increase in different wells in the eastern area.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2022년도 학술발표회
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• pp.450-450
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• 2022

The study aims to develop scenarios for efficient groundwater use using existing wells in order to prepare for an eventual drought. In the recent decades, droughts are not only intensifying, but they are also spreading into territories where droughts used to be less intense and relatively infrequent. With the increasing disaster, efficient groundwater use is urgently needed not only to prevent the problem of groundwater depletion but also drought risk reduction. Thus, the research addressed the problem of efficient aquifer use as source of water during drought and emergencies. The research focused on well network system applied to Yanggok-ri in Korea using simulation models in visual MODFLOW. The approach consists to variate groundwater pumping rate in the most important wells used for irrigation across the study area and evaluate the pumping effect on water level fluctuation. From the evaluation, the pumping period, appropriate pumping rate of each well and the most vulnerable wells are determined for a better groundwater management. The project results divide the study area into two different regions (A and B), where the wells in the region A (western part of the region) show a crucial drop in water level from May to early July and in august as consequence of water pumping. While wells in region B are also showing a drawdown in groundwater level but relatively less compare to region A. The project suggests a scenarios of wells which should operate considering water demand, groundwater level depletion and daily pumping rate. Well Network System in relevant project, by pumping in another well where water is more abundant and keep the fixed storage in region A, is a measure to improve preparedness to reduce eventual disaster. The improving preparedness measure from the project, indicates its implication to better groundwater management.