• 한국관개배수논문집
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• 제7권2호
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• pp.57-65
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• 2000

The effect of land use of an alluvial watershed in the upper North Han river basin on groundwater quality were investigated. Existing 20 farm wells were selected as monitoring wells representing different land uses of residential, arable(paddy and field),

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권3호
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• pp.1-9
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• 2018

This study is aimed to quantitatively evaluate the effects of drought on groundwater system in rural areas. For this purpose, the standardized groundwater level index (SGI) was used for 68 groundwater monitoring wells. To determine accumulation period (AP) which represents the month with the highest correlation coefficient between SGI and SPI, correlation analysis between the two for 68 wells were peformed. The results indicated the AP values ranged in 1~3 months for most of the well, but it was 7~10 months in some wells. These results can be interpreted such that the total amount of groundwater will not decrease significantly in long-term drought situations unlikely the reservoirs with the high AP values. The nationwide maximum AP values were 4.1 and 4.0 in Chungbuk-do and Gyeongnam-do, while the minimum AP values were 1.8 and 2.0 in Gangwon-do and Chungnam-do, respectively. The maximum and minimum values of correlation coefficient were 0.623 and 0.459 in Gyeongnam-do and Chungnam-do/Chungbuk-do, respectively. Consequently, it could be concluded that the wells with low AP value tend to respond to short-term drought, but it has little effect on groundwater system when the long drought occurs.

• Geomechanics and Engineering
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• 제38권2호
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• pp.107-123
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• 2024

The drilling angle of the well is an important factor that can affect the sand production process and make its destructive effects more severe or weaker. This study investigated the effect of different well angles on sand production for the Asmari Formation, located in one of the oil fields southwest of Iran. For this purpose, a finite difference model was developed for three types of vertical (90°), inclined (45°), and horizontal (0°) wells with casing and perforations in the direction of minimum and maximum horizontal stresses, then coupled with fluid flow. Here, finite element meshing was used, because the geometry of the model is so complex and the implementation of finite difference meshes is impossible or very difficult for such models. Using a combined FDM-FEM model with fluid flow, the sand production process in three different modes with different flow rates for the Asmari sandstone was investigated in this study. The results of numerical models show that the intensity of sand production is directly related to the in-situ stress state of the oil field and well drilling angle. Since the stress regime in the studied oil field is normal, the highest amount of produced sand was in inclined wells (especially wells drilled in the direction of minimum horizontal stress) and the lowest amount of sand production was related to vertical wellbore. Also, the Initiation time of sand production in inclined wells was much shorter than in other wellbores.

• 한국광학회:학술대회논문집
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• 한국광학회 1996년도 Advance Program of 13th optics andquantum Electronics conference, 1996제13 회 광학 및 양자전자 학술 발표회 논문 요약집
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• pp.30-30
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• 1996

• 한국습지학회지
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• 제23권4호
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• pp.342-351
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• 2021

이 연구의 목적은 MODFLOW를 이용하여 신규 지하수 관정 추가로 인한 영향을 예측하기 위해 지하수의 변화와 지하수두 또는 매개변수 민감도에 미치는 영향을 평가하는 것이다. 이 연구에서는 동해시의 전천유역 하류지역을 대상으로 두 가지 조건을 모의하였다. 첫 관측된 지하수위값을 이용하여 자연상태 정류 흐름을 모의 할 수 있는 매개변수를 결정한 후, 이미 설치되어 있는 관정까지 포함하여 모형을 구축하였다. 구축된 모형을 이용하여 지하수 관정의 추가 설치에 따른 영향을 모의하였다. 두 번째는 동해시의 물 부족 문제를 해결하기 위한 방법으로 관정을 계획하고 모의하였다. 모의 결과, 최대 지하수위 저하는 첫 번째 대수층에서 약 0.35m로 나타났으며, 이는 해수의 침입은 발생하지 않는다는 것과 관정의 계획이 물 부족의 해결책으로 무리가 없다는 것을 나타낸 것이다. 마지막으로 MODFLOW에서 사용되는 매개변수의 민감도 분석을 실시하였다. 민감도 분석 결과에서 초기 수두, 비등방성 계수, 수리전도도 및 일반수두경계가 민감한 매개변수로 판명되었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 International Symposium
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• pp.89-110
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• 2003

최근 현장(In situ)에서의 토양 및 지하수 오염 정화는 오염물질을 현장에서 추출해 지상에서 처리하는 것이 아니라, 직접 현장에서 미생물 혹은 화학물질과 오염물질의 혼합을 통한 분해기 작을 이용해, 오염물질을 제거하는 과정을 의미한다. 이러한 현장오염정화 기법 중 하나가 Figure 1에 도시한 수직흐름처리정(Horizontal Flow Treatment Wells, HFTWs)으로 2개의 정(well) 중간지점에 반응물질을 설치한 후 각각의 정에서 상향 및 하향흐름을 발생시켜 주위의 지하수를 순환시키면서 정화하는 기법이다.

• 한국환경과학회지
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• 제22권5호
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• pp.609-623
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• 2013

Fluctuation patterns of groundwater level as a factor that reflects the characteristics of groundwater system can be categorized as the various types of aquifer with the time-series data. Time-series data on groundwater level obtained from 115 monitoring wells in Jeju Island were classified according to variation types, which were largely affected by rainfall(Dr), rainfall and pumping(Drp), and unknown cause(De). Analysis results indicate that 106 wells belong to Dr and Drp and the ratio of the wells with the wide range of fluctuation in the western and northern regions was higher than that in the eastern and southern regions. From the results that Drp is relatively higher than Dr in the western region which has the largest agricultural areas, groundwater level fluctuations may be affected significantly due to the intensive agricultural use. Non-parametric trend analysis results for 115 monitoring wells show that the increasing and decreasing trends as the ratio of groundwater levels were 14.8% and 22.6%, respectively, and groundwater levels revealed to be increased in the western, southern and northern regions excluding eastern region. Results of correlation analysis that cross-correlation coefficients and the time lags in the eastern and western regions are relatively high and short, respectively, indicate that the rainfall recharge effect in these regions is relatively larger due to the gentle slope of topography compared to that in the southern and northern regions.

• The Plant Pathology Journal
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• 제16권3호
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• pp.125-129
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• 2000

A rapid and efficient assay to determine melanin biosynthesis inhibition of Magnaporthe grisea, a causal agent of the rice blast, by chemicals was developed. Wells in 24-well plates were loaded with spore suspension of the fungus and three known melanin biosynthesis inhibitors of KC10017, tricyclazole, and carpropamid. Subsequent color changes of mycelia and culture media in the wells were observed 7 days after incubation. The wells treated with KC10017 (an inhibitor of polyketide synthesis step and/or pentaketide cyclization step) became colorless, whereas tricyclazole (an inhibitor of 1, 3, 8-trihydroxynaphthalene reductase) or carpropamid (an inhibitor of scytalone dehydratase)-treated wells exhibited red color. They did not show any inhibitory effect on fungal growth. The inhibition of reaction steps prior to 1, 3, 6, 8-tetrahydroxynaphthalene formation was easily determined by colorless medium and mycelia. However, it was impossible to distinguish between inhibition of reduction steps and inhibition of dehydration steps by colors of the cultures. It was accomplished through HPLC analysis of the melanin biosynthesis-involving pentaketide metabolites accumulated by the inhibitors. Through screening of a number of synthetic chemicals using the in vitro assay, we could find a novel chemical group of melanin biosynthesis inhibitor.

• Journal of Applied Biological Chemistry
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• 제42권4호
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• pp.186-190
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• 1999

Isotope ratio ($^{15}N/^{14}N$) and nitrate-nitrogen concentration in groundwater were measured to investigate the effect of chemical fertilizer and livestock manure on temporal variations in nitrate-nitrogen concentration and to estimate the contribution of fertilizer and manure to groundwater contamination by nitrate. Four study wells from a rural area in Kyonggi province were selected. One well was located on an upper site from a livestock feedlot, and the others were situated at lower sites from the feedlot. The ${\delta}^{15}N$ values were analyzed by a stable isotope ratio mass spectrometer (Micromass, VG Optima IRMS). Reproducibility of the method and precision of the mass spectrometer were below 1.0 and 0.1‰, respectively Even though study wells were located at the same area, nitrate-nitrogen concentrations and ${\delta}^{15}N$ values differed and fluctuated during the sampling period. The ${\delta}^{15}N$ values of well located at upper site from the feedlot were extremely variable (-1.48~20.80‰). The ranges of ${\delta}^{15}N$ value of three wells situated at lower sites from the feedlot were 11.83~20.73 (ave. 16.11), 8.90~11.73 (ave.11.01), and 5.29~12.73‰ (ave. 8.21‰) with increasing distance from the feedlot. The average values of contribution proportion of nitrogen derived from livestock manure to nitrate-nitrogen in groundwater were 79% for the well closet to the feedlot, 44% for the well most distant from the feedlot, and 56% for the well in between the two wells.

• 한국농공학회논문집
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• 제62권6호
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• pp.119-129
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• 2020

Through 3D seepage analysis of pressure relief well installed on the embankment of agricultural reservoir, the effects of reducing pore water pressure and hydraulic gradient, and increasing piping safety, depending on diameter (0.2, 0.4, 0.6 m) and space (10, 25, 50 m) of relief well, were analyzed. The conclusions drawn through this study are as follows. i) At the location of pressure relief well, pore water pressure decreases by 25.3~62.5%, and hydraulic gradient decreases by 22.4~55.7%. ii) Between relief wells, pore water pressure decreases by 2.7~40.3%, and hydraulic gradient decreases by 2.8~47.0%, which are relatively less than at the cross section of installed location of relief well. iii) Piping safety factor by critical hydraulic gradient increases by 28.9~125.6% at the location of relief well and increases by 2.9~88.8% between relief wells. iv) Seepage analysis needs to be performed by the 3D method to make evaluation of seepage at the location of relief well and between relief wells possible. v) Additional evaluation is required for various conditions such as waterhead, engineering characteristics of embankment body and its foundation, location, diameter, spacing and depth of pressure relief well.