• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.514-514
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• 2016

최근 도시화가 도시의 물순환에 미치는 영향을 최소화하기 위한 저영향개발에 대한 연구가 많아짐에 따라, 기존 도시의 미관개선과 비점오염원의 유입을 사전에 차단하기 위하여 다양한 제품들이 개발되고 있다. 기존의 벤치플륨관을 개선하고자 개발된 환경반구형수로관은 프리캐스트(Precast)콘크리트 제품으로 상부에 투수구를 통해서 빗물이 유입되도록 제작된다. 투수구에는 플라스틱 필터가 적용되며 빗물만 배제하여 배수 시키토록 고안되었다. 플라스틱 필터는 폐PVC 스크랩을 재활용하여 제작되며 제품표면은 다양한 재료로 마감하여 콘크리트 노출면을 최소화 하였다. 빗물이 투수구를 통해서 유입되기 때문에 원활하게 빗물을 차집하여 배수 할 수 있는가에 대한 수리성능을 검토하기 위한 수리실험을 수행하였다. 최대허용우수유입량은 실제 환경반구형수로관에 적용되는 필터와 마감재료를 적용하여 쇄석필터층의 두께의 변화가 환경반구형수로관의 배수성능 미치는 영향을 검토하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1691-1695
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• 2010

본 연구에서 AFDA(Approximate Full Distribution Approach)를 사용하여 하수관의 불능확률을 정량적으로 산정할 수 있는 신뢰성 모형이 개발되었다. 여러 도시의 연 최대강우강도(Yearly Maximum Rainfall Intensity)를 이용하여 그 확률분포함수를 분석하였고 우수관(Storm sewer)의 불능확률 산정을 위한 신뢰성 모형에 적용하였다. 연 최대강우강도 자료의 분석결과 우리나라 중부지방의 여러 중소도시에 대한 연 최대강우강도의 확률분포함수는 Gumbel분포와 일치하는 것으로 나타났다. 신뢰성 모형은 불능확률의 신뢰함수를 구하기 위해 하중(Load)을 규정하는 식은 합리식이 사용되었고 용량(Capacity)를 규정하는 식은 Darcy-Weisbach공식과 Manning의 공식이 사용되었다. 이렇게 개발된 신뢰성 모형을 실제 우수관에 적용하여 불능확률을 산정하는 신뢰성 해석을 수행하였다. Y자형 우수관망에서 2개의 관으로 유입하는 각각의 유량이 그 관의 허용유량을 초과할 경우를 불능확률로 가정하였고, 나머지 관의 경우는 두 개의 관으로부터 유입하는 유량과 그 세 번째 관의 매설지역의 우수유입량의 합이 그 관의 허용유량을 초과할 경우를 불능상태(state of system failure)로 간주하여 불능확률을 정량적으로 산정하였다. Darcy-Weisbach공식과 Manning의 공식을 사용한 신뢰성 해석결과를 비교하였으며 우수관 직경의 변화에 따른 불능확률을 산정하였다. 특정한 수치(설계직경)이하일 경우 불능확률이 급격히 증가하는 것으로 나타났다. 따라서 실제 우수관의 유효직경이 설계직경에 항상 가깝도록 불순물을 제거하는 것이 최선의 관리 방법이며 불능확률을 줄이는 최선의 방법일 것이다. 본 연구에서 개발된 신뢰성 모형은 우수관의 운용, 관리, 감독은 물론 설계에 활용이 가능 할 것이다.

• Journal of Korean Society of Disaster and Security
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• v.12 no.4
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• pp.1-13
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• 2019

Recently, as the occurrence frequency of sudden floods due to climate change increased, it is necessary to install the facilities that can cope with the initial stormwater. Most researches have been conducted on the design of facilities applying the Low Impact Development (LID) and the reduction effect on rainfall runoff to examine with 1D or 2D numerical models. However, the studies on the examination about flow characteristics and stability of pipe network systems were relatively insufficient in the literature. In this study, the stability of the pipe network system in rainwater storage tank was examined by using 3D numerical model, FLOW-3D. The changes of velocity and dynamic pressure were examined according to the number of rainwater storage tank and compared with the design criteria to derive the optimal design plan for a rainwater storage tank. As a results of numerical simulation with the design values in the previous study, it was confirmed that the velocity became increased as the number of rainwater storage tank increased. And magnitude of the velocity in pipes was formed within the design criteria. However, the velocity in the additional rainwater storage pipe was about 3.44 m/s exceeding the allowable range of the design criteria, when three or more additional rainwater storage tanks were installed. In the case of turbulence intensity and bottom shear stress, the bottom shear stress was larger than the critical shear stress as the additional rainwater storage was increased. So, the deposition of sediment was unlikely to occur, but it should be considered that the floc was formed by the reduction of the turbulence intensity. In addition, the dynamic pressure was also satisfied with the design criteria when the results were compared with the allowable internal pressure of the pipes generally used in the design of rainwater storage tank. Based on these results, it was suitable to install up to two additional rainwater storage tanks because the drainage becomes well when increasing of the number of storage tank and the velocity in the pipe becomes faster to be vulnerable to damage the pipe. However, this study has a assumption about the specifications of the rainwater storage tanks and the inflow of stormwater and has a limitation such that deriving the suitable rainwater storage tank design by simply adding the storage tank. Therefore, the various storage tank types and stormwater inflow scenarios will be asked to derive more efficient design plans in the future.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.433-437
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• 2015

XP-SWMM은 유한차분방법에 의한 천수방정식을 기반으로 하는 TUFLOW 엔진을 탑재하여 1차원 솔루션 엔진과 동적으로 연결하여 범람원에서의 흐름거동을 2차원으로 해석할 수 있다. 유역에서 발생한 모든 유출량은 해당 소유역의 노드(맨홀)로 유입되며 2차원 침수양상은 관로상태에 따라 노드를 통해 역류한 유출수에 의해서 폰딩(Ponding)되는 조건으로 모의한다. XP-SWMM의 침수범람 모의는 침수범람 상황을 가시적으로 보여주는데 상당한 강점을 가지고 있으나 실제 지형여건에 따른 자연현상을 엄밀하게 모델링하는데 일정부분 한계가 있다. 모형의 한계는 담수된 노드의 수위로 인한 에너지 영향(오리피스 흐름)으로 인접관로의 침수가 부가적으로 유발할 수 있다는 점이며 실제 대부분의 경사지에서의 침수상황은 노드에 유출수가 담수되지 않고 하류로 지면을 따라서 확산(Diffusion)되어 담수영향으로 인한 인접관로 침수가 추가적으로 유발되지 않을 가능성이 매우 높다. 즉, XP-SWMM의 담수허용조건, 지반고 2D연결 옵션은 유역에서의 침수발생량을 과대평가 할수 있으며 특정 유역에서는 실제 침수발생 상황과 차이가 발생 할 수 있는 것이다. 본 연구에서는 서울시 광화문 일대의 효자배수분구 우수관로를 SWMM으로 구성하고 강우조건 95mm/hr에서 노드조건을 담수허용, 2D연결, 담수없음 조건으로 모형을 수행하여 침수모의 결과를 비교, 검토하였다. 전체관로 노드조건을 담수허용, 2D연결로 설정하게 되면 담수없음 조건과 비교하여 1.2-2.8배의 침수발생량이 추가로 발생하는 것으로 검토되었다. 즉, 담수없음 조건의 경우 침수발생시 노면 수위상승 인한 동수경사 영향이 반영된 압력관로 영향이 반영되지 않아 노드간 침수발생량이 중복되지 않는다. 반면, 담수허용이나 2D연결로 모형을 수행할 경우 지면의 경사가 충분히 있는 지역에 침수가 발생하더라도 일정 수심이상의 수두(동수경사선)가 형성되어 침수를 추가로 유발하는 것으로 보인다.

• Journal of Korea Water Resources Association
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• v.35 no.6
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• pp.639-650
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• 2002

Reservoir operations during the flood season should consider both the flood control and water supply objectives. This study proposed Set Control Algorithm (SCA) as a reservoir operation method, which guarantees both objectives. The concept behind SCA is to provide operators with a set of actions that guarantee feasibility, given a set of operational constraints, and to let them select decisions within a set that satisfies other considerations. The inflow sets used in this study included; observed data, synthetic data, and ESP(Ensemble Streamflow Prediction) scenarios. Applied to the Chungju Dam operations, SCA was compared to the variable flood restricted elevation, as well as the current flood restricted elevation. A 5-year simulation analysis showed that SCA performed better than the other operation methods, and that SCA coupled with ESP performed best among the SCA cases.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.967-976
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• 2010

AFDA (Approximate Full Distribution Approach) model of FORM (First-Order Reliability Model) which can quantitatively calculate the probability that storm sewer reach to performance limit state was developed in this study. It was defined as a failure if amount of inflow exceed the capacity of storm sewer. Manning's equation and rational equation were used to determine the capacity and inflow of reliability function. Furthermore, statistical characteristics and distribution for the random variables were analyzed as a reliability analysis. It was found that the statistical distribution for annual maximum rainfall intensity of 10 cities in Korea is matched well with Gumbel distribution. Reliability model developed in this study was applied to Y shaped storm sewer system to calculate the probability that storm sewer may exceed the performance limit state. Probability of failure according to diameter was calculated using Manning's equation. Especially, probability of failure of storm sewer in Mungyeong and Daejeon was calculated using rainfall intensity of 50-year return period. It was found that probability of failure can be significantly increased if diameter is decreased below the original diameter. Therefore, cleaning the debris in sewer pipes to maintain the original pipe diameter should be one of the best ways to reduce the probability of failure of storm sewer. In sewer system, two sewer pipes can flow into one sewer pipe. For this case, probability of system failure was calculated using multiple failure mode. Reliability model developed in this study can be applied to design, maintenance, management, and control of storm sewer system.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.1025-1032
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• 2009

This study investigated a possibility to develop an adsorption process for volatile organic compounds (VOCs) of the solvent emitted during dry cleaning. Pitch activated carbon fiber (ACF) was chosen as an adsorbent of VOCs, and an electric swing adsorption process was utilized for the reproduction of the adsorbent after the completion of VOCs adsorption. Effects of ACF types and several solvents such as trichloroethylene (TCE) and toluene were examined on breakthrough curves and amounts of adsorbed VOCs. ACF was pretreated under various conditions in order to enhance the amounts of the adsorbed VOCs. Temperatures and voltages were measured for the reproduction of the ACF after full adsorption. ACF having micropores exhibited high adsorption of TCE, and high surface area of ACF could increase the adsorption property of toluene. In general, ACF could adsorb 41~54% TCE of the adsorbent weight. The increase of inlet VOCs concentration significantly decreased the breakthrough time and slightly lowered the amounts of adsorbed VOCs. Thus, ACF could effectively adsorb VOCs in low concentration in the feed stream. ACF pretreated by heat under vacuum showed excellent toluene adsorption with controlling oxygen functional groups on the ACF surface, which revealed that vacant carbon site could be the adsorption point of toluene. Most adsorbed toluene was desorbed at $150^{\circ}C$.

• Journal of Korea Water Resources Association
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• v.41 no.7
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• pp.693-700
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• 2008

Detention pond has an important role in peak flow reduction to mitigate flood damage. Design of detention pond is accomplished through the preliminary stage, and design stage in general. New development projects produce increased peak flow and flow amounts. In this case it is necessary to design the detention pond easily and simply. A simplified design method of the detention pond is suggested in this study. Used design variables are peak flow ratio(${\alpha}$) and storage ratio($S_r$). ${\alpha}$ is the peak flow ratio of before and after development of the basin. $S_r$ is a ratio of storage volume to total runoff volume. Applicability of the proposed method was also proved. The simple procedure of detention pond design is proposed in this study.

• Korean Journal of Environmental Agriculture
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• v.39 no.1
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• pp.36-43
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• 2020

BACKGROUND: Wicheon watershed has the largest irrigation area among the mid-watershed of Nakdong river. However, no investigation of irrigation water quality has been conducted on the Wicheon watershed, which evaluates the effects on the soil quality and crop cultivation. Therefore, this study aims to provide various assessments of water quality of Wicheon watershed as the scientific basic data for efficient agricultural activities. METHODS AND RESULTS: Water sampling was performed in five locations of the first tributaries of Wicheon. Wicheon watershed showed clean water quality with very low organic matters and safe water quality from metals at all points of investigation. It was estimated that the natural chemical components of Wicheon watershed were originated from water-rock interaction in Gibbs diagram. All samples were concentrated in the type of Ca-HCO₃-Cl in the Piper diagram. The quality of irrigation water was evaluated with sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), and percent sodium (%Na). The values of these water quality indices were in the range of 0.37-0.67, -2.11--0.24, 41.13-84.52% and 11.28-21.84%, respectively, and were classified as good grades at all sites. CONCLUSION: The water quality of Wicheon watershed was very low in salt, indicating good irrigation water suitable for growing agricultural products. We hope that the results of this study will be used as the basic data for the cultivation of agricultural products and promotion of their excellence.