Determination of monitoring systems and installation location to prevent debris flow through web-based database and AHP

Jun, Hwandon,Min, Dae-Hong,Yoon, Hyung-Koo Taylor & Francis 2017 Marine georesources & geotechnology Vol.35 No.8

CPS 기반 도시 수자원 시스템 실시간 시뮬레이션 및 운영관리 의사결정 지원기술 개발

전환돈(Hwandon Jun) 대한환경공학회 2020 대한환경공학회 학술발표논문집 Vol.2020 No.11

Estimation of sediments in urban drainage areas and relation analysis between sediments and inundation risk using GIS

Moojong, Park,Hwandon, Jun,Minchul, Shin IWA Publishing 2008 Water Science & Technology Vol.58 No.4

<P>Sediments entering the sewer in urban areas reduce the conveyance in sewer pipes, which increases inundation risk. To estimate sediment yields, individual landuse areas in each sub-basin should be obtained. However, because of the complex nature of an urban area, this is almost impossible to obtain manually. Thus, a methodology to obtain individual landuse areas for each sub-basin has been suggested for estimating sediment yields. Using GIS, an urban area is divided into sub-basins with respect to the sewer layout, with the area of individual landuse estimated for each sub-basin. The sediment yield per unit area for each sub-basin is then calculated. The suggested method was applied to the GunJa basin in Seoul. For a relation analysis between sediments and inundation risk, sub-basins were ordered by the sediment yields per unit area and compared with historical inundation areas. From this analysis, sub-basins with higher order were found to match the historical inundation areas.</P>

상수관망의 신뢰도 산정을 위한 개별 관의 파괴 확률을 고려한 상수관 파괴모의 기법

전환돈,Jun. Hwandon 한국방재학회 2012 한국방재학회논문집 Vol.12 No.4

상수관망의 신뢰도 산정은 상수관망의 정확한 운영상황을 파악하기 위해서 중요지만 널리 받아들여지는 상수관망의 신뢰도 산정을 위한 방법은 없다. 관파괴와 이에 따른 영향을 바탕으로 한 Jun 등이 제안한 모델은 상수관망의 운영주체에서 실질적으로 활용이 가능한 기법이다. 그러나, Jun 등의 모델에서는 각 관의 파괴확률을 같게 설정하여 관파괴 모의를 실시하였기 때문에 실제 상수관망에서 발생하는 관파괴 양상을 정확하게 반영하지 못하였다. 따라서 본 연구에서는 각각의 관별 파괴확률을 고려하여 관파괴 모의를 가능케 Jun 등의 모델을 개선하여 상수관망의 신뢰도를 산정할 수 있는 모델을 제안하였다. 각각의 관별 파괴확률을 관경과 관길이를 바탕으로 산정하는 회귀식을 이용하여 산정한 후 이를 상수관망 신뢰도 산정을 위한 관파괴 모의에 적용하였다. 제안된 모델을 실제 상수관망에 적용하여 Jun 등의 모델과 본 연구에서 제안된 모델에 의해 산정되는 상수관망의 신뢰도를 비교하였다. 비교 결과 개별 관의 관파괴 확률을 반드시 고려하여야만 정확한 상수관망의 신뢰도 산정이 가능한 것으로 나타났다. Estimation of the reliability of a Water Distribution System(WDS) is important to understand the current operating condition of the system. Although, there is no widely accepted method to estimate the reliability of a WDS, the Jun`s model which is based on the pipe failure simulation and its impact can be efficiently adopted for the purpose by the water utility. In the model, however, it is assumed that the pipe failure probability of each pipe is even and this assumption may bring unrealistic estimation of the reliability of a WDS since with this assumption, the actual pipe failure characteristics occurred in the WDS cannot be simulated. For this reason, in this study, we suggest a modified method of the Jun`s model to consider the individual pipe`s failure probability. The regression equation which is based on diameter and length of the pipe is used to estimate the failure probability of the individual pipe and then, the pipe failure simulation is performed. The suggested model is applied to a real WDS to compare the results of the two models. Comparing them, it is concluded that the failure probability of the individual pipe should be considered to estimate the accurate reliability of a WDS when it is estimated by the pipe failure simulation.

Porosity estimation of unsaturated soil using Brutsaert equation

Choo, Hyunwook,Jun, Hwandon,Yoon, Hyung-Koo Elsevier 2018 Soil dynamics and earthquake engineering Vol.104 No.-

<P><B>Abstract</B></P> <P>Although the porosity is a crucial parameter for understanding the soil behavior under static and dynamic loading, estimating the porosity of unsaturated soil is difficult owing to the various input parameters required. The objective of this study is to suggest a technical method to obtain the level of porosity based on the elastic wave velocity in unsaturated soil. The Brutsaert model, which utilizes the theory of wave propagation, is applied to modify the proposed method in terms of the porosity of unsaturated soil. The soil compressional wave velocity is gathered through a seismic refraction survey, and the porosity distribution at different depths is estimated. A dynamic cone penetration test is applied to verify the converted porosity based on the compressional wave. The two porosities estimated through the wave propagation and penetration show similar trends. Furthermore, a special validation is performed to determine whether the energy dissipation can be ignored in the compressional wave propagations under this experiment condition. The results of this study indicate that the suggested technique is useful for obtaining the porosity in unsaturated soil.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Porosity is a crucial parameter for understanding soil behavior. </LI> <LI> The study deduces the porosity by using compressional wave velocity. </LI> <LI> The Brutsaert model is applied to organize the equation. </LI> <LI> The special validation of energy dissipation is also verified. </LI> </UL> </P>

유출곡선지수(CN)를 이용한 침투시설 간편 설계법 개발

최소현(Sohyun Choi),전환돈(Hwandon Jun),이동엽(Dongyeop Lee),황수덕(Soodeok Hwang),박종표(Jongpyo Park) 한국방재학회 2023 한국방재학회논문집 Vol.23 No.4

최근 기후변화가 가속화되어 자연재해의 규모 및 강도가 커지고 있으며 특히 국지적 집중호우의 발생빈도가 급증하고 있다.도시유역은 불투수면적 비율이 높아 집중호우 발생 시 상대적으로 침수발생가능성이 높으며 인구 및 물적자원이 집중되어 있어 대규모 피해를 야기할 수 있다. 홍수피해를 저감하기 위해서 기존에는 하천개수, 하수도정비, 우수저류지 설치 등의 방법을사용하였으나 최근에는 저영향개발 기법의 사용이 제안되고 있다. 그러나 저영향개발(Low Impact Development, LID) 시설은소규모로 여러 위치에 설치하며 강우유출 분석을 위한 매개변수가 많으므로 설계에 많은 인력과 시간이 소요된다. 따라서 본 연구에서는 보다 간편하고 효율적인 LID시설의 설계방안을 제시하기 위해 LID시설 규모에 따른 우수유출 저감효과를 분석하고 각 시설능력에 상응하는 유역의 유출곡선지수(Curve Number)를 추정하여 시설면적비와 유출곡선지수의 상관관계를 분석하였다. 결과적으로 LID시설 설치 전 유역의 유출곡선지수와 시설이 전체 유역에서 차지하는 면적비를 통해 LID시설을 설치한것과 동일한 우수유출 저감효과를 가지는 유출곡선지수를 산정할 수 있는 관계식을 도출하였다. 이를 통해 LID시설을 SWMM에직접 입력하지 않고 재산정한 유출곡선지수를 이용해 모델을 구축 및 분석하는 LID시설의 간편 설계법을 제시하고자 한다. As climate change accelerates, the scale and intensity of natural disasters are increasing, and the frequency of localized heavy rains is increasing rapidly. Urban watersheds have a high ratio of impervious areas. So there is a high possibility of flooding in the event of torrential rain, and large-scale damage can occur because the population and material resources are highly concentrated. River improvements, sewerage maintenance, and rainwater storage installations are frequently used to reduce flood damage. More recently, low-impact development (LID) techniques have been proposed; however, LID facilities are installed on a small scale and in various locations. In addition, they require many parameters for a rainfall-runoff analysis; consequently, the design of these facilities require too much manpower and time. In this study, we analyze the rainfall-runoff reduction effect based on the size of a facility to present a simpler, more efficient design method. Next, the curve number (CN) corresponding to the capacity of each facility is estimated and the correlation between the facility’s area ratio and the CN is analyzed. As a result, a relational expression that can calculate the new CN with the same rainfall-runoff reduction effect as the installed LID facility was derived by using the CN before the installation of the LID facility and the facility area ratio. Thus, we present a simple design method using the recalculated CN without directly entering LID facilities into a storm water management model (SWMM).

The effect of climate change on Byeongseong stream's water quantity and quality

Choi, Daegyu,Jun, Hwandon,Shin, Hyun Suk,Yoon, Young Sam,Kim, Sangdan Informa UK (Taylor Francis) 2010 Desalination and Water Treatment Vol.19 No.1

The Proportional Hazards Modeling of Water Main Failure Data Incorporating the Time-dependent Effects of Covariates

Park, Suwan,Jun, Hwandon,Agbenowosi, Newland,Kim, Bong Jae,Lim, Kiyoung Springer-Verlag 2011 Water resources management Vol.25 No.1

혼합 정수계획 모형을 활용한 제한급수 계획

김재희(Kim, Jaehee),전환돈(Jun, Hwandon) 한국방재학회 2017 한국방재학회논문집 Vol.17 No.3

Water shortages may cause trouble to people’s life. Therefore, the damages of water shortages must be minimized by allocating water resources efficiently. In order to overcome this problem, it is necessary to analyze and optimize water distribution network. Therefore, we present a mathematical model for optimal allocation of water resources among samll blocks in the water supply network for situations where water supply is restricted. The model is a mixed-integer goal programming model that does not only minimize the total amount of water shortages but also the number of occurrences of water shortages considering the priorities of water demands for small blocks. With the model, we can minimize the severity and balance the occurrences of water shortages among each water block and verify the utility of the model.

공간적 분포특성을 고려한 강우관측소 평가

이지호(Lee, Jiho),전환돈(Jun Hwandon),김형수(Kim, Hyungsoo) 대한토목학회 2012 대한토목학회 학술대회 Vol.2012 No.10