• The Journal of Engineering Geology
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• v.34 no.1
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• pp.13-24
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• 2024

The purpose of this study is to identify the geology, geologic structure, hydrogeology and geomorphic characteristics of the Nari Basin and establish the controls on the discharge of water 20,000~40,000 m³/day from the Choosan Yongchulso, Ulleung Island, South Korea. Pumice and lapilli tuffs showing well-developed stratification are the predominant rock types surrounding the spring. The spring shows a structure whereby discharge occurs along a lens-like erosion cave formed by differential erosion of strata comprising tuff or pumice tuff. The Choosan Yongchulso is located at the point where the planation surface of the Nari Basin' ends and steep slopes begin. The basin is bounded on all sides by these steep slopes, except in the north, where the Choosan Yongchulso is located. Given these geomorphic characteristics, the Choosan Yongchulso is regarded as the ultimate outlet of the basin catchment area.

• Proceedings of the Korea Contents Association Conference
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• 2013.05a
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• pp.97-98
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• 2013

최근 빈번하게 발생하고 있는 국지성 집중호우로 인한 해안 도시지역의 내수침수 원인 및 면적을 XP-SWMM 모형을 이용하여 분석하였다. 이 연구의 대상은 해안과 인접한 지역이며, 유역의 면적은 $2.74km^2$이고 관로의 총연장은 11.20km이다. 대상지역을 32개의 소유역과 67개의 하수관로로 XP-SWMM 모형의 입력자료를 구축하였다. 대상유역에 대한 강우분석을 수행하여 2년, 5년, 10년, 20년, 30년, 50년 빈도의 강우량을 결정하였으며, 각 빈도의 강우사상에 대하여 조위조건을 반영한 침수해석을 수행하였다. 우수관거시스템과 연계된 TUFLOW 흐름모형을 이용하여 침수범람지역을 모의하였다. 모의 결과 모든 빈도에 대하여 내수침수 현상이 발생하는 것으로 나타났으며, 빈도별로 최대침수심은 0.485~0.673m, 침수면적은 $88,600{\sim}230,700m^2$로 예측되었다. 대상유역의 침수발생 양상은 하수관로의 유량이 맨홀을 통해 지표면으로 분출되는 현상이 발생하며, 이 지역의 하류로 침수범위가 확대되는 것으로 나타났다. 이런 현상은 상류에 위치한 소유역의 우수 유출량을 집수하는 집수정의 용량과 하류로 유하시키는 우수관로의 통수단면이 부족한 것을 주요 원인으로 생각할 수 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1192-1200
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• 2007

A general rainfall outflow in urban drainage has early time of concentration because urban drainage areas are most paved area. In general, rainfall outflow is flowed in drainage pump station and is discharged to rivers in urban areas. However it is excluded through drainage pumps about a heavy rainfall which exceed the design rainfall and the rainfall outflows increase the urban inundation risk. A current pump operation is control according to water level of collecting well or reservoir in drain pump station. But recently, the localized downpours are happened frequently in urban drainage and the current pump stations are frequently incapable of the heavy rainfall outflows. In this study, a real urban inundation was simulated and the drain capacity of drain pump station was evaluated by analysis about flood-factor in urban underground passage. Then the analysis about the inundation was done by the simulation about the real rainfall which cause the inundation. Also, in the simulation the inundation risk and the evaluation of flood-factor were analyzed according to change of the pump operation rule.

• The Journal of Engineering Geology
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• v.29 no.2
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• pp.123-136
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• 2019

This study examines the effect of collector well installed to reduce groundwater level in the regions with the occurrence of landcreep, a soil mass movement triggered by instability on slopes. Slopes are prone to failure as a result of instability caused by its internal, topographic and geological properties as well as due to external factors such as rainfall and earthquake. In Korea during the rain season, rainfall infiltration affects the groundwater level in soil, building up porewater pressure and load, and finally drives slopes to collapse. Slope failure caused by rainfall infiltration has been leading to a drastic forest degradation. The studied slope is located adjacent to a valley, its terrain corresponds to piedmont gentle slope, while the upper part of the failure surface is steep. After reinforcing the terrain where landcreep had occurred and installing collector well on the slope, we measured the changes in the groundwater level. In order to analyze the relationship between the well and the slope, we calculated the ratio of groundwater level to rainfall before and after the installation of the collector well. As a result, it is confirmed that the ratio increases after the installation of the well, which in turn reduces the groundwater level. Analysis of the change in groundwater level after 3, 7, 15 days antecedent rainfall showed that the higher the overall groundwater level, the less the value ($r_p$) of groundwater level-rainfall ratio is, while the value becomes relatively greater when the groundwater level is low. In particular, if a slope has a large catchment basin as is in the case of the studied site, antecedent rainfall affects groundwater level in the order of 3 < 7 < 15 days.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.259-268
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• 1988

Clay deposits in the vicinity of the Gwangpo Bay, southern coast of Korea, occur restrictively in anorthositic masses. Laumontite and meta-halloysite are the predominant clay minerals with iron oxides at the uppermost surface. Chlorite and halloysite occur in deeper zone. Beneath the main clay horizon, but not above, some anorthositic rocks are pervasively altered to quartz, sericite, chlorite, pyrite and montmorillonite along the hydrothermal channels. The hypotheses of hydrothermal and weathering origins of the clay minerals are tested by multi-component equilibrium calculations of the reactions of modified hydrothermal water and rain water with anorthositic rocks at $100^{\circ}C\;and\;25^{\circ}C$, respectively. The calculated mineralogy from the reaction with rain water resembles natural mineral assemblage except for abundance in laumontite. The result implies that the weathering process is the main machanism of the formation of clay deposits in the area.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.2
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• pp.90-100
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• 2012

This study centering on 10 village - Bangjuks analyzed multifunctionality value of village Bangjuks which have been main water treatment system in Korean traditional villages. On the basis of understanding the structure and character of components such as the well, common spring, village waterway and others which making water-flow and consisting of aquatic system in Korean traditional village Bangjuk, the conclusion as the instrumental device of social and ecological role and ecological watershed management, securing the ecosystem soundness of the damaged or deteriated aquatic ecosystem due to the industrialization and urbanization is as below; 1. The traditional village Bangjuk was environmentally friendly hydraulic system which gathers waterways of village into a point including sewage water, retains and flows out to village through agricultural waterway. Through this Bangjuk, they have managed sewage and rainfall runoff flowed out village efficiently. It is not only a detention system of water but a kind of eco-friendly system that flow out water into the rivers after reusing and filtering it. 2. Around five traditional villages and five villages after modernization, this study classified the types of village Bangjuk as three types considering geographic location, size, etc; marsh type of low swamp, high water -low rice field type of natural flow stucture, low water - high rice field type requiring artificial irrigation facility. All the five traditional villages were turned out to be marsh type of low swamp. Geoji, Sanjeri, Ma-am, Yangchon of the agricultural villages were high water-low rice filed type, and Sangchoenri village was classified low water-high rice field type. 3. This study checked up the function of water purification of village Bangjuk. In Wonteo and Geji villages affected by discharge of village sewer and domestic sewage, the efficiency of ammonia nitrogen($NH_3-N$) and total phosphorus(T-P) was 56~95%, which was high. In Sangcheonri and Sanjeri villages strongly affected by stall and farmland, the efficiency of suspended solids(SS) was 70~85%, and that of total nitrogen(T-N) and total phosphorus(T-P) was 5.3~65%. 4. A water purification system can be found out in the system of village Bangjuk that filter out village sewage and rainfall runoff flowed through the settle and filter of pollution source and denitrification of plants. Through this system of village Bangjuk, it must be used as the basic facilities for the ecological watershed management. The sewage management system of village Bangjuk as a eco-filter must be used and studied as an eco-friendly facility for the ecological watershed management around the subwatershed and catchment.

• Economic and Environmental Geology
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• v.48 no.6
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• pp.467-475
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• 2015

The Deokjin Pond is one of the places representing Jeonju City's history but has the poor water quality. The pond has a storage of $88,741m^3$ and a drainage area of $3.77km^2$. It has been maintained only by the groundwater pumped from the upstream wells and the direct rainfalls on the water surface since the old streams replenishing the pond were turned into a part of the sewer system due to indiscreet urbanization. The lack of replenishing water as well as the organic-rich bottom sediment were suggested as two main causes deteriorating the water-ecosystem. In this study, possible measures obtaining waters for restoration of Deokjin Pond ecosystem are discussed. It is estimated that the present pond can be replenished about 32 times a year by the runoff when the drainage system in the watershed is recovered to a state before urbanization. To support this, the drainage system is compared with that of nearby Osong Pond, which shows relatively better water-ecosystem. Even though Osong Pond has a drainage area one-seventh of that of Deokjin Pond, its storage is more than the half of it. It is because its watershed has a near natural drainage system where the rain mostly infiltrates into soil and slowly discharges into the pond. Therefore, it is believed that the low impact development (LID), which is known as a technique restoring the water circulating system to a condition before development, would be helpful in obtaining waters required for Deokjin Pond ecosystem management.

• Journal of Korea Water Resources Association
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• v.45 no.7
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• pp.643-656
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• 2012

There has been an increase for the landslide areas and restoration expenses due, in large part, to the increased locally heavy rains caused by recent climate change as well as the reckless development. This study carried out a slope stability analysis by the application of distributed wetness index, using the GIS-based infinite slope stability model, which took the root cohesion effect into consideration, for part of Mt. Umyeon in Seoul, where landslide occurred in July 2011, in order to compensate the defects of existing analysis method, and subsequently compared its result with the case on the exploitation of lumped wetness index. In addition, this study estimated the distributed wetness index by methodology, applying three methods of specific catchment area calculation: single flow direction (SFD), multiple flow direction (MFD), and infinity flow direction (IFD), for catchment area, one of the variables of distributed wetness indices, and finally implemented a series of comparative analysis for slope stability by methodology. The simulation results showed that most unstable areas within the study site were dominantly located in cutting-area surroundings along with the residential area and the mountaintop and unstable areas of IFD and lumped wetness index method were similar while SFD and MFD provided smaller unstable areas than the two former methods.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.32-32
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• 2022

본 연구는 농경지가 주로 분포되어있는 영산강 유역(3,371.4 km²)을 대상으로 농업용수 건전성 및 취약성 평가를 수행하였다. 먼저, 농업용수 건전성은 관개 기간에 농업용수 확보를 위한 유역 환경 요소(하천, 토지이용, 수문, 수질, 수생태, 서식지)로 정의하였으며, 취약성은 용수공급에 영향을 주는 인위적인 변화 요소(기후변화, 불투수층 변화, 농업용수 수요량 변화, 토지피복 변화)로 구분하였다. 각 요소의 sub-index는 1개의 지수로 정규화하여 평가하였으며 Percentile rank 방법으로 계산하였다. 분석결과 영산강 하류의 나주시(5004) 유역의 건전성 및 취약성 지수가 각각 0.33, 0.92로 농업용수 공급에 취약한 것으로 분석되었다. 이에 따른 회복력 및 유지·조치 우선순위 분석결과 또한 농업용 수리시설(저수지, 양수장, 취입보, 집수암거, 관정)을 이용한 농업용수 확보가 시급한 것으로 분석되었다. 최종적으로 본 연구에서 제시한 농업용수 건전성 및 취약성 지수는 장기간에 걸친 유역 변화분석이 가능하고, 농업용수 공급 상황을 예측함으로써 향후 농업용수 확보를 위한 시설물 설치계획 수립에 근거자료로 활용할 수 있을 것으로 판단된다.

• Journal of Soil and Groundwater Environment
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• v.11 no.5
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• pp.20-34
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• 2006

This study was undertaken to assess the anthropogenic impact on trace metal concentrations (Zn, Cu, Pb, Cr, Ni, and Cd) of roadside sediments (N = 70) from No.7 national road within the watershed of Hoidong Reservoir in Pusan City and to estimate the potential mobility of selected metals using sequential extraction. We generally found high concentrations of metals, especially Zn, Cu and Pb, affected by anthropogenic inputs. Compared to the trace metal concentrations of uncontaminated stream sediments, arithmetic mean concentrations of roadside sediments were about 7 times higher for Cu, 4 times higher for Zn, 3 times higher for Pb and Cr and, 2 times higher for Ni and As. Speciation data on the basis of sequential extraction indicate that most of the trace metals considered do not occur in significant quantities in the exchangeable fraction, except for Cd and Ni whose exchangeable fractions are appreciable (average 29.3 and 25.8%, respectively). Other metals such as Zn (51.4%) and Pb (45.2%) are preferentially bound to the reducible fraction, and therefore they can be potentially released by a pH decrease and/or redox change. Copper is mainly found in the organic fraction, while Cd is highest in the exchangeable fraction, and Cr and Ni in the residual fraction. Considering the proportion of metals bound to the exchangeable and carbonate fractions, the comparative mobility of metals probably decreases in the order of Cd>Ni>Pb>Zn>Cr>Cu. Although the total concentration data showed that Zn was typically present in potentially harmful concentration levels, the data on metal partitioning indicated that Cd, Ni and Pb pose the highest potential hazard for runoff water. As potential changes of redox state and pH may remobilize the metals bound to carbonates, amorphous oxides, and/or organic matter, and may release and flush them through drain networks into the watershed of Hoidong Reservoir, careful monitoring of environmental conditions appears to be very important.