• Journal of the Korean association of regional geographers
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• v.12 no.1
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• pp.172-178
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• 2006

There has been tremendous increase of disaster related damages since 1990's. Especially flood occurred in summer season highly populated area has led to demolish a lot of facilities and buildings within a short time period. This is to figure out the way to predict the vulnerable flood inundation area by past records of inundation and and geographic information available. The comparative study on 1998 and 1999 flood inundation area in Munsan and Gokneung river shows that 5 degree of slope and 10 m elevation level are dividing index to draw the vulnerable area. This study is to suggest the relatively easy method to predict flood vulnerable area and to apply the results to prepare for protecting the facilities and the people with other thematic geographic database.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1375-1383
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• 1994

The water distribution system problem consists of finding a minimum cost system design subject to hydraulic and operational constraints. Since the municipal water distribution system problem is nonconvex with multiple local minima, classical optimization methods find a local optimum. An outer flow search - inner optimization procedure is proposed for choosing a better local minimum for the water distribution systems. The pipe network is judiciously subjected to the outer search scheme which chooses alternative flow configurations to find an optimal flow division among pipes. Because the problem is nonconvex, a global search scheme called Stochastic Probing method is employed to permit a local optimum seeking method to migrate among various local minima. A local minimizer is employed for the design of least cost diameters for pipes in the network. The algorithm can also be employed for optimal design of parallel expansion of existing networks. In this paper one municipal water distribution system is considered. The optimal solutions thus found have significantly smaller costs than the ones reported previously by other researchers.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.666-666
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• 2012

수문조사는 효율적이고 안정적인 물관리를 위한 기초자료로서 매우 중요함에도 불구하고, 예산 부족 등의 문제로 인해 국가하천 및 방재상 중요 하천유역을 중심으로 이루어졌다. 따라서 국내에서는 지방하천, 특히 해안유역 지방하천의 수문조사가 매우 미흡한 실정이다. 본 연구에서는 영산강서해와 섬진강남해 해안유역의 지방하천을 대상으로 도상 및 문헌을 통해 우선 현황을 파악하였으며, 이를 토대로 현장조사 등을 통해 수리 수문학적 중요성, 사회 경제적 분석과 수문조사 적정성을 검토하여 영산강서해유역에 총 7 개 지점, 섬진강남해유역에 총 13 개 지점에서 수위 및 유량 관측이 필요한 것으로 판단되었다. 이 중 12개 지점은 관측소 신설이 필요하며 이 지점들에 대해서는 수위관측시설의 설치 및 운영과 유량측정에 필요한 제반사항을 제시하여 향후 수위관측소 설치 및 유량측정 등에 활용할 수 있도록 하였다. 본 연구의 결과는 국토해양부 영산강홍수통제소 관할 해안유역에서의 균형적인 수문조사에 기여할 수 있을 것으로 기대되며, 향후 수위관측소 신설 후 생산되고 제공되는 수문자료들은 대상 해안유역에서의 효율적 물관리를 위한 중요 기초자료로서 충분히 활용될 것이다.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.359-369
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• 2008

For the design and effective management of underground storage caverns, preliminary investigation on the hydrogeologic parameters around caverns and analysis on the groundwater flow must be carried out. The data collection is very imporatnat task for the hydrogeologic design so various hydraulic tests have been performed. When analyzing the injection/fall off test data, existing graphical method to estimate the parameters in Theis' equation is widely used. However this method has some sources of error when estimating parameters by means of human faults. Therefore the method of estimating parameters by means of statistical methods such as regression type is evaluated as a useful tool. In this study, nonlinear regression analysis for the Theis' equation is suggested and applied to the estimation of parameters for the real field interference data around underground storage caverns. Damping parameter which reduce the iteration numbers and inhance the convergence is also introduced.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2B
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• pp.199-209
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• 2010

A finite element model for analyzing surface water flow was developed. Shallow water equation was discretized and solved by Galerkin and Newton-Raphson method. Triangular or rectangular elements can be mixed together to construct meshes. The algebraic equation was solved by frontal method which is very efficient in finite element problem. The developed model was applied to rectangular meandering channel with two bends and transverse velocities and water depth distributions were examined. High velocity was located near the inner bank at the apexes of the bends and velocity distribution was symmetrical about the centerline at the midsection of two bend and super elevation also occurred. Simulation results showed very good agreement with measured data. Another numerical simulation was carried out in mild, steep, adverse and abrupt bottom change slope and channels with weir. 12 water surface profiles of gradually varied flow were correct in terms of hydraulic interpretation.

• Journal of Korea Water Resources Association
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• v.41 no.7
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• pp.725-735
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• 2008

Due to recent climate change, flood damages have been increased, but it is difficult to construct large hydraulic structure for flood control such as dam because of environmental, economical and political problems. For this reason, several researches and studies have tried to use washland as an alternative of hydraulic facility. Because sizes of washlands are usually smaller than those of dams or reservoirs, there can be many available locations for washlands in a basin and proper combination of these locations can reduce flood disasters efficiently. However, in case there are many available locations for washland and many combinations to consider, it is very difficult to determine the optimal combination which yields to provide the maximum benefit. For the more, hydraulic approach that used in previous studies to calculate flood reduction effect needs a lot of time for calculation and sometimes can not give the final result. In this study, the flood reduction effect of washland is calculated by hydrologic approach and decision making model for optimal location of washland using genetic algorithm for determination of optimal solution is developed. The developed model has been applied to the Ansung River basin in order to examine the applicability and the application result shows that developed model can be used as decision making model for washland.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.53-63
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• 2018

The hydrolysis of organic solid waste, such as sludge, is the rate-limiting step of the anaerobic digestion. The longer rate-limiting step lead to decrease of treatment efficiency and increase hydraulic retention time and anaerobic digester. Therefore, the pre-treatment has been applied for accelerating the hydrolysis step. This study was investigated the effects of pre-treatment of waste activated sludge using ultrasonic and alkaline integrated treatment simultaneously. The results showed the cumulative methane production and the methane production rate increased while the lag phase decreased. Therefore ultrasonic and alkaline integrated pre-treatment of waste activated sludge resulted in acceleration of hydrolysis step in anaerobic digestion.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.4
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• pp.59-67
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• 1988

Anaerobic digestion at the temperature of $35-55^{\circ}C$ was conducted using an artificial sludge of uniform composition. The hydraulic retention time of 5 days was chosen because the temperature effect was effectively shown at a high loading. Inhibition of the methane fermentation decreased as the temperature increased. Acid fermentation was prevalent at the mesophilic and intermediate temperatures, while active methane fermentation took place at $55^{\circ}C$. Temperature not only affects activity of the microorganisms, but also affects physical and chemical properties of the sludge, Digestion inhibition was much reduced when the feed sludge was diluted, and active methane fermentation was possible at all temperatures. The digestion efficiency was governed by the organic loading rate as well as the hydraulic 10ading rate. No reduction of the digestion efficiency at $40-45^{\circ}C$, which had been referred to a critical temperature range, was observed. The digestion efficiency increased monotonically from mesophilic to thermophilic range. Improved settling properties of digested sludge was also recorded at higher temperatures.

• Journal of the Korea Organic Resources Recycling Association
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• v.19 no.1
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• pp.102-108
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• 2011

Characteristics of hydrogen production from various food wastes in anaerobic batch reactors were evaluated to assess the energy potential of organic wastes. Organic wastes which were used in this study were scallion as vegetable, apple as fruit, rice as grain and pork as meat. Ultimate hydrogen yield of scallion, apple, rice and pork were 0.46, 0.47, 0.62 and $0.05mol\;H_2/mol\;hexose$, respectively. On the other hand, hydrogen production rates of scallion, apple, rice and pork were 0.013, 0.021, 0.014 and $0.005mol\;H_2/mol\;hexose/h$, respectively. These results indicated that anaerobic hydrogen fermentation from food waste except for meat was effective in removing organic material as well as producing renewable energy. Volatile fatty acids increased as hydraulic retention time was increased. In the hydrogen fermentation, acidification degree of rice was measured as the highest rate of 75.8% whereas pork was found as the lowest rate of 35.2%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3B
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• pp.153-159
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• 2012

In this study, we proposed modified settling basins transformed by substituting the downstream sill for low head weirs such as generic labyrinth weir and inclined crest labyrinth weir worked as internal baffles. Laboratory experiments were carried out to understand hydraulic characteristics inside of the settling basin to improve the efficiency of sedimentation rate. For a quantitative analysis, we suggested the headwater ratio($H_t/P$), the magnification ratio(L/W) and the inflow rate per total crest length($q_L$) as primary analysis indexes for sedimentation efficiency. Six different types of settling basin were used for labscaled pilot tests by distinguishing with internal structures. Based on results, the variation of headwater ratio with the change of magnification ratio would highly affect the deposition efficiency(%) and it was improved under specific condition that repeating arrange number(N) of labyrinth weir was between 2 and 4. Also, the regression analysis showed that initial condition and shape for improving sedimentation efficiency were plotted on the graph for both $q_L{\geq}3.5cm^2/s$ and $L/W{\leq}3.5$. It would be expected that the geometrically optimized labyrinth settling basin could be designed with proper deposition efficiency for inflow rates of influent and required area of settling basin utilizing the proposed analysis index in this study.