• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.752-757
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• 2006

유역 내의 지속적인 개발과 도시화로 유출량이 증가하면서 하도의 통수능을 초과하게 됨에 따라 제방을 증고하게 되고 특히 하류부로 갈수록 유량의 급격한 증가로 제방고를 높여야 하는 악순환이 반복되었다. 이에 따라 유역의 홍수량을 하도 이외의 유역 내에서 분담하고 하도 중심의 치수 대책이 아닌 유역 전체에서 홍수를 제어해야 한다는 유역종합치수대책이 중요한 대안으로 떠오르고 있다. 유출저감시설은 이미 개발된 도시유역의 홍수량을 조절하는 데 유용할 뿐 아니라 새롭게 개발이 시행되는 유역에서는 개발로 인한 홍수 증가량을 분담하는 수단으로써 필수적으로 설치되어야 한다. 최근에는 일률적으로 임시 및 상시 저류지 등의 빈도설계를 통하여 개발 이후의 첨두유량이 개발 이전의 첨두유량 보다 크지 않도록 우수배제시스템을 설계하고 있으나 저류지와 같은 유출저감 시설을 유역출구에 설치함으로써 첨두유량만을 개발이전의 수준으로 유지할 뿐 여전히 유출량의 증가 및 홍수 도달시간이 빨라지는 문제점을 근본적으로 해결하지 못하고 있다. 본 연구에서는 현행 재해영향평가제의 법적 테두리안에서 개발사업으로 인한 증가된 홍수 저감대책을 수립하는 과정에서 몇가지 개선방안을 제시, 연구하고자 한다. 즉, 사업지구 하류하천 규모를 감안한 저류지의 적정 설계빈도의 채택과 저류지의 다목적 이용방안에 대해 검토하여 홍수재해로부터 안전하고 환경친화적인 개발사업이 될 수 있는 방안을 제시코자 한다.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.132-137
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• 2018

Compared with general rivers, fluctuations of the water level and the river bed are severe in the tidal river. In hydro-dynamic aspect, such fluctuation gives different river-bed data to us according to observing period. The time-dependent river-bed data and pre-estimation of the Manning's roughness coefficient which is the key factor of numerical modelling induces uncertainty of evaluating the design flood level. Thus it is necessary to pay more attention to calculate the flood level at tidal rivers than at general rivers. In this study, downstream of the Imjin River where is affected by tide of the West Sea selected as a study site. From the numerical modelling, it was shown that the unsteady simulation gave considerable mitigation of the water level from the starting point to 15 km upstream compared to the steady simulation. Either making a detention pond or optional dredging was not effective to mitigate the flood level at Gugok - Majung region where is located in the downstream of the Imjin River. Therefore, a more sophisticated approach is required to evaluate the design flood level estimation before constructive measures adopted in general rivers when establishing the flood control plan in a tidal river.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.63-64
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• 2014

NIR(New Inspection Regime, hereinafter NIR) relating to the PSC(Port State Contorl, hereinafter PSC) has implemented in Asia-Pacific region under Tokyo-MOU from last January 2014. The most noticable difference between NIR and existing TF(Target Factor, hereinafter TF) is to evaluate company performance and to conduct PSC with flexible inspection interval on the basis of Ship Risk Profile; High Risk Ship, Standard Risk Ship and Low Risk Ship.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4
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• pp.129-134
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• 1992

This paper presents the relation between risk and safety factor for optimal storm sewer design in urban area. For reliability analysis of the storm sewer, uncertainty of the various parameters of constituting equation determining the capacity and load of storm" sewer is considered and risk is determined. In this study, reliability analysis method is applied to Seongsan detention reservoir basin which area is $381,000m^2$ Darcy-Weisbach equation is used for determining capacity of the storm sewer and rational formula is used for determining load. Safety factor representing ratio of the sewer capacity and design flowrate is calculated, and relating with risk. Then risk and safety factor with return period is obtained and it is used for optimal design of storm sewer.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.2
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• pp.1-15
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• 2020

In this study, the characteristics of crop damage area by flooding for 113 middle range watersheds during 2000-2016 were analyzed and future crop damage area by flooding were analyzed using 13 GCM outputs such as hourly maximum rainfall, 10-min maximum rainfall, number of days of 80 mm/day, daily rainfall maximum, annual rainfall amount associated with RCP 4.5 and RCP 8.5 scenarios and watershed characteristic data such as DEM, urbanization ratio, population density, asset density, road improvement ratio, river improvement ratio, drainage system improvement ratio, pumping capacity, detention basin capacity, and crop damage area by flooding. A constrained multiple linear regression model was used to construct the relationships between the crop damage area by flooding and other variables. Future flood index related to crop damage may mainly increase in the Mankyung watershed, Southwest part of Youngsan and Sumjin river basin and Southern part of Nackdong river basin. Results are useful to identify watersheds which need to establish strategies for responding to future flood damage.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.2
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• pp.213-218
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• 2008

Prediction models for post-chlorination require complicated information of reaction time, chlorine dosage considering flow rate as well as environmental conditions such as turbidity, temperature and pH. In order to operate post-chlorination process effectively, the correlations between inlet and outlet of clear well were investigated to develop prediction models of chlorine dosages in post-chlorination process. Correlations of environmental conditions including turbidity and chlorine dosage were investigated to predict residual chlorine at the outlet of clear well. A linear regression model and autoregressive model were developed to apply for the post-chlorination which take place time delay due to detention in clear well tank. The results from autoregressive model show the correlationship of 0.915~0.995. Consequently, the autoregressive model developed in this study would be applicable for real time control for post chlorination process. As a result, the autoregressive model for post chlorination which take place time delay and have multi parameters to control system would contribute to water treatment automation system by applying the process control algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1285-1289
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• 2008

최근 도시지역의 확대와 고밀도화에 따른 도시근교의 산림, 논밭, 녹지 등이 감소하고, 도로나 건축물 등의 증가로 인해 불투수 유역이 확대되어, 원래 그 토지가 유지하고 있던 보수 유수 기능이 현저히 저하되고 있다. 그 결과 강우 시 표면 유출량의 증가와 유출시간의 단축이 현저하게 되고, 도시하천이나 하수도 유하 능력을 넘는 홍수가 자주 발생하고 있다. 또한 빗물 침투량이 줄어들어, 용천수 고갈, 하천의 평상시 유량감소가 나타나게 된다. 이러한 문제를 해결하기 위해 최근 유역 내에 저류시설과 침투시설 등 유출저감효과를 기대할 수 있는 여러 가지 시설의 활용방안이 꾸준히 모색되고 있다. 본 연구에서는 이러한 내배수 홍수분담시설 중 저류와 침투의 기능을 모두 갖추고 있는 쇄석공극저류시설의 효율성을 분석하였다. 또한 쇄석저류지와 규모와 형태가 유사한 우수저류지와의 비교를 통해 상대적인 효율성을 평가하였다. 그 결과 두 시설이 같은 규모를 가진다고 가정할 때, 우수저류지가 쇄석저류지에 비하여 월등한 유출저감효과를 보이는 것으로 파악되었다.

• The Korean Journal of Community Living Science
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• v.22 no.1
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• pp.21-33
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• 2011

This study examined the effects of family environmental variables and parent-child communication on the self-esteem of delinquent and non-delinquent juveniles. For this study, a questionnaire was administered to 117 non-delinquent juveniles living with their parents as high school students and 98 delinquent juveniles aged 15~18 who live in detention centers for adolescence. The data was analyzed using t-test, cross-tab, correlation, and hierarchical multiple regression analysis with SPSS /PC window program. Based on these results, the following conclusions were drawn. First, it was found that non-delinquent juveniles show a more open communication style with their parents than delinquent juveniles. Furthermore, a high level of parent-child communication was associated with high self-esteem in adolescents. Second, although physical environment such as family type or economic status influences an adolescents' self-esteem, the degree of positive parent-child communication style has a much greater effect on an adolescents' self-esteem. Finally, in terms of the effects of family environmental variables and parent-child communication style on self-esteem, parent-child communication style has a stronger effect on delinquent juveniles than non-delinquent juveniles. These results shows the importance of communication style between parent and child, especially for families with delinquent juveniles.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.201-209
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• 1993

The purpose of this study is to analyze the reliability of storm sewer system and AFOSM method is applied on Sinjeong detention basin area to decide the applicability of AFOSM method. The Rackwitz Algorithm, which is suitable for minimizing the error due to non-linearity, is used to find the failiure point. The performance functions are established to calculate the risk, rational formula is used to determine the load and Manning equation and Darcy-Weisbach equation are used to determine the sewer capacity, and the results are 0.119, 0.127, respectively. The Risk-Safety Factor relation for each return period is derived and the designing of storm sewer system based on reliability analysis is enabled.

• Journal of ILASS-Korea
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• v.16 no.2
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• pp.69-75
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• 2011

This article presents computational fluid dynamics (CFD) simulations of sub-micron particle movements and flow characteristics in laboratory-scale electrostatic precipitator (ESP) without corona discharge, and for simulation, it uses the commercial CFD program (CFD-ACE) including electrostatic theory and Lagrangian-based equation for sub-micron particle movement. For validation of CFD results, a simple cylindrical type of ESP is simulated and numerical prediction shows fairly good agreement with the analytical solution. In particular, the present study investigates the effect of particle diameter, inlet flow rate, and applied electric potential on particle collection efficiency and compares the numerical prediction with the experimental data, showing good agreement. It is found that the particle collection efficiency decreases with increasing inlet flow rate because the particle detention time becomes shorter, whereas it decreases with the increase in sub-micron particle diameter and with the decrease of applied electric voltage resulting from smaller terminal electrostatic velocity.