• Journal of Information Processing Systems
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• v.17 no.6
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• pp.1097-1114
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• 2021

The primary objective of this work was to discover a solution for the survival of people in an emergency flood. The geographical information was obtained from remote sensing techniques. Through helpline numbers, people who are in need request support. Although, it cannot be ensured that all the people will acquire the facility. A proper link is required to communicate with people who are at risk in affected areas. Mobile sensor networks with field-programmable gate array (FPGA) self-configurable radios were deployed in damaged areas for communication. Ad-hoc networks do not have a centralized structure. All the mobile nodes deploy a temporary structure and they act as a base station. The mobile nodes are involved in searching the spectrum for channel utilization for better communication. FPGA-based techniques ensure seamless communication for the survivors. Timely help will increase the survival rate. The received signal strength is a vital factor for communication. Cognitive radio ensures channel utilization in an effective manner which results in better signal strength reception. Frequency band selection was carried out with the help of the GRA-MADM method. In this study, an analysis of signal strength for different mobile sensor nodes was performed. FPGA-based implementation showed enhanced outcomes compared to software-based algorithms.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.821-834
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• 2015

This study presents the analysis of flow and bed change characteristics considering bed protection work built on the immediate downstream of weir to protect river bed from scouring. The study area is 37km reach from Hyunpoong station to Masuwon station including Hapcheon- Changryoung multi-function weir in the Nakdong river. CCHE2D model is calibrated and validated for evaluating the flow and bed change characteristics during Typhoon Kompasu in 2010. Three simulation conditions are set up: Case 1 is a natural channel without installation of weir. Case 2 involves an installation of weir in the natural channel. Case 3 involves an installation of weir with bed protection in the natural channel. Flood frequency (50, 100 and 200yr) is applied to each scenario to analyze the effects of bed protection work. While the sediment rate is increased in the downstream of fixed gate and sluice-type gate, river bed scouring rate is increased in the downstream of lift-type gate in Case 2 comparing with the results of Case 1. The river bed scouring is not occurred in the immediate downstream of weir (~30m) due to the effect of bed protection, but larger amount of sediment is occurred in the downstream of weir (60m~) which the bed protection is not installed comparing with the results Case 1. Through the results of simulation considering bed protection work, this study would be helpful to expect bed change and operate the weir as well as manage.

• Progress in Medical Physics
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• v.19 no.4
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• pp.291-297
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• 2008

The purpose of this study is to optimize a parallel-hole collimator for small gamma camera having the pixellated crystal array and evaluate the effect of crystal-collimator misalignment on the image quality using a simulation tool GATE (Geant4 Application for Tomographic Emission). The spatial resolution and sensitivity were measured for the various size of hexagonal-hole and matched square-hole collimators with a Tc-99m point source and the uniformity of flood image was estimated as a function of the angle between crystal array and collimator by misalignment. The results showed that the spatial resolution and sensitivity were greatly improved by using the matched collimator and the uniformity was reduced by crystal-collimator misalignment.

• Ecology and Resilient Infrastructure
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• v.9 no.3
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• pp.194-205
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• 2022

Sandbars formed by sediment transportation and sedimentation are some of the most important habitats for specific wildlife and they provide an aesthetic landscape in streams. The purpose of this study was to understand the successional process of the colonization and development of early vegetation over time on sandbars exposed by the opening of a gate at a downstream weir. We selected the following four study sites in the Geumgang River, South Korea: three weir-upstream sites with different gate-opening times and a control site that was not affected by weir operation. Changes in the structural characteristics and spatial distribution of the riparian vegetation on the sandbars exposed after opening the gate at the weir were surveyed according to the different exposure periods of the sandbars at the study sites. The newly formed sandbars accounted for more than 33% of the area of the existing floodplain in the three weir-upstream sites of the Geumgang River after opening the gate at the weir. Nine main plant communities were distributed on the exposed sandbars. These communities were classified as annual mesophytic, perennial hydrophytic, perennial hygrophytic, subtree, and tree vegetation based on their species traits. As the duration of exposure of the sandbar increased, the area of the bare sandbar and the annual herbaceous and perennial hydrophytic communities decreased, and the areas occupied by perennial hygrophytic, subtree, and tree communities increased. Changes in vegetation on the sandbar were classified into three types of succession according to the condition of the aquatic habitat before the gate-opening and the degree of physical disturbance caused by the water flow after the gate-opening. The types of succession were: 1) succession starting from hydrophytes in the lentic aquatic zone, 2) succession starting from annual herbaceous hygrophytes in the lotic aquatic zone, and 3) willow-dominated succession in the disturbed channel side. Our results suggested that the dynamics of successional changes in vegetation should be considered during weir operation to ecologically manage the habitats and landscape of the fluvial landforms, including sandbars in streams.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.4
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• pp.24-36
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• 2003

In this study, we estimated the seasonal fluctuations of water quality and effect of small tide embankment in coastal water around the Muan Peninsula, which is located in the northern part of Mokpo city, and layer farming ground is spread around there. Some physical and chemical factors were analyzed to characterize water quality from Jan. to Oct. in 1994. The results were as follows: Dissolved oxygen was slightly under saturation in the almost areas of July, and in some bottom layer at ebb tide of October. Distribution of COD showed high values that over 2㎎/L in October and flood tide of April by the discharge of freshwater and resuspension of benthic sediment, which exceeded water quality criteria II. Maximum values of dissolved inorganic nitrogen ware appeared in surface layer during the flood tide of October, while minimum of that showed in surface layer in April. Concentration of dissolved inorganic phosphorus was higher at July than the others, which ranged from 0.24 to 2.08㎍-at/L. Mostly mean values of N/P ratio were lower than 16, it mean that nitrogen is more limiting nutrient than phosphorus for the growth of phytoplankton. The values of eutrophication index were in the range of 0.07~0.81. However, very high values due to increase of COD were estimated near the tide embankment and southern part in relation to tidal current in October. Water quality around tide embankment was suddenly changed worse within a short period after opening the water gate during the rainfall.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.6
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• pp.489-495
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• 2011

Fossil fuel energy has become a worldwide environmental issue due to its effect on global warming and depletion in its supply. Therefore, the interest in developing alternative energy source has been rising. Ocean energy, especially, has gained strength as an alternative energy source for its unlimited supply with low secondary risks. Among all the ocean energy, the west coast of Korea holds the field of large-scale energy development because of its distinctive tidal range. Tidal power plant construction at the sea may expedite multi development effects such as bridge roles, tourism resource effects and adjustability of flood inundation at the inner bay. This study introduces the validity of tidal power plant construction at Garilim Bay in west coast of Korea by examining anticipated hydraulic characteristics using EFDC model. Through EFDC numerical simulations, the feasibility of Garolim Bay as a tidal power plant field has been proved. And the most effective tidal power plant construction would be to install hydraulic turbine in the west side of bay entrance where ebb current is stronger, and install water gate in the east side of bay entrance where the flood current is superior.

• Journal of Korea Water Resources Association
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• v.40 no.11
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• pp.877-886
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• 2007

An urban drainage system consists of two major systems : flood drainage facilities and operating practices. The facilities are composed of sewer networks, gates, and pumping stations and the operating practice consists of pump or gate operation. Then, a real time simulation system which is able to simulate urban runoff and the pump operation and to consider the backwater effect is required to operate efficiently the pump. With this system, the efficient pump operating rule can be developed to diminish the possible flood damage on urban areas. In this study, a real time simulation system was developed using the SWMM 5.0 DLL and Visual Basic 6.0 equipped with EXCEL. Also, for developing efficient pump operating Rules, two new Rules were suggested. The first Rule is designed to operate pumps considering the condition of sewer networks such as depths of each junction. The second is to discharge all the amount of inflow at each time step. Results obtained by those Rules were compared with one by the current pump operating Rule which is able to consider only the depth of the retard basin. The developed model was applied to Joonggok retard basin and verified their applicability.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.31-31
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• 2011

해마다 반복되는 수해를 대비하여 배수펌프장을 설치하고, 취수보를 철거하는 방법으로 수해예방시스템을 고도화 시키고 있지만, 증가하는 홍수량에 대한 대비책으로는 역부족이다. 따라서, 홍수 피해에 대한 선제적 대응방안으로 강변저류지를 설치하여 상습 침수구역에 대한 대비가 진행되고 있다. 강변저류지 설치를 통해 유역의 홍수량을 분담하고 인접지역의 침수피해를 예방하는 역할을 기대할 수 있다. 국내에서도 영월군의 상습침수구역에 대한 대비책 중 하나로 국토해양부 및 강원도가 함께 영월강변저류지 조성공사를 추진하고 있다. 영월군은 지난 2002년과 2003년에 태풍 '루사'와 '매미'로 인해 심각한 피해를 입었으며, 2006년 집중호우시에도 현재 저류지 예정지역인 방절리 일대와 영월읍 시가지, 북쌍리 등이 대규모로 침수피해를 입은 바 있다. 해당 저류지의 총 넓이는 68만 8천 $m^2$로 물 290만 $m^3$을 가두어 둘 수 있는 규모이다. 하지만, 영월 강변저류지의 저류용량이 290만 $m^3$에 불과해 홍수예방 효과가 미흡하다는 지적이 잇따르고 있다. 따라서, 적절한 수문운영을 통해 홍수저감량과 저류효과를 증대시키는 홍수예방 방안을 제안하고자 한다. 본 연구에서는 유전알고리즘의 적용을 통하여 강변저류지에 설치된 수문의 운영 방법을 개선함으로써 홍수저감량을 최대화하고자 하였다. 수리 수문학적 모형인 HEC-RAS, HEC-I 모형을 연계 운용하여 평창강 유역을 대상으로 수문분석, 홍수유출량 분석, 하류 하천의 홍수영향 분석 결과를 도출하였다. 강변저류지 설치로 인하여 저류지 직하류부를 기준으로 약 $131\;m^3/s$의 첨두홍수량 저감 효과가 발생하는 것으로 검토되었지만, 본 연구에서 제안된 최적화 기법이 적용된 수문운영 방법을 병행하여 운영한다면 추가적으로 $24\;m^3/s$를 저감하는 효과를 얻을 수 있다. 효율적으로 저류지를 운영하여 홍수피해를 사전에 방지하고 나아가 다른 저류지 유역에도 본 연구를 적용하여 홍수피해를 줄이고 합리적으로 용수를 이용하는데 기여할 수 있을 것으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.297-301
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• 2011

최근에는 전 지구적으로 이상기후 현상이 빈번히 발생하고 있으며 이로 인해 과거와는 달리 예측하기 어려운 집중호우와 돌발강우에 따른 피해가 증가하고 있는 추세이다. 이러한 이상 강우현상에 의해 하천 및 주변의 내 외수의 수위 상승을 야기하며, 이로인해 제내지의 침수 위험성이 그 어느 때보다 높은 실정이다. 특히, 내수침수의 경우는 외수에 따른 범람보다는 내수배제 불량에 따른 침수 빈도와 범위가 증가되고 있는 상황이며, 이에 대한 대비가 절실히 요구되고 있다. 주기적으로 반복되는 내수침수에 의한 국민의 재산과 인명피해를 최소화하기 위해서는 침수피해 위험도가 높은 지역을 파악 관리하여야 하며, 지역의 주민에게도 지역의 특성을 주지시켜야 한다. 이와 함께 침수 발생시 피해 최소화를 위한 피난 경로와 피난 장소 등을 상세히 제공하여 신속한 재난 대처와 함께 인명과 재산의 피해를 최소화하여야 한다. 침수예상지도는 태풍이나 집중호우에 의한 침수 발생시 제방의 월류 및 붕괴, 내수배제 불량 등으로 인한 예상 침수지역을 강우빈도별로 나타내고, 침수면적과 깊이를 표현한 지도로서 방재형 국토관리의 정책결정과 침수 피해에 대한 대민 홍보의 수단으로 활용되고 있다. 국내에서도 홍수에 의한 피해가 나날이 커지고 국토의 개발에 따른 자연 재해가 많아짐에 따라 홍수에 의한 피해를 최소화하기 위한 노력의 일환으로 침수예상지도의 제작 및 관리 시스템의 필요성이 증대되고 있다. 본 연구에서는 지석천 유역의 태풍 및 집중호우에 의한 과거 침수실적을 조사하여 침수실적도를 작성하 였으며, 내 배수 불량에 따른 홍수빈도, 강우빈도별 침수예상도를 작성하였다. 이를 위해 현재 보편적으로 이용되고 있는 1차원 수리 수문 모델인 미 공병단의 HEC-HMS, HEC-RAS 모델과 내 배수 영향 검토를 위해 한국농어촌공사에서 개발된 GATE 프로그램을 이용하였다. 이렇게 계산된 연구 대상지역의 침수심과 침수면적을 GIS를 이용하여 침수예상도를 작성하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.358-358
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• 2018

대청댐은 준공이후 현재까지 37년의 수문자료가 축적되었으며 총 43회의 수문방류를 하여 연간 1.16회의 수문방류를 시행하였다. 본 연구에서는 그동안 수문방류와 지속적으로 최신화한 K-water 저류함수법을 이용하여 수문방류기간중 총강우량 현황과 강우량에 따른 11개의 강우분포형(증가, 감소, 증가감소, 균일, 감소증가, 증가계단, 감소계단, Huff1, Huff2, Huff3, Huff4)의 현황분석, 강우량별 분포형별 유출율을 분석하여 금년도 및 향후 발생이 예상되는 홍수시 수문방류결정에 활용하기 위함이다. 홍수발생 원인을 살펴보면 홍수기 초반에는 장마전선으로 인한 강우가 원인이며, 장마가 끝난 7월말~8월경에는 태풍의 영향을 받는다. 또한, 최근 엘리뇨 및 라니냐 현상의 출현에 따른 기후변화 및 이상기후의 영향으로 예측이 어려운 국지성 돌발호우의 증가로 홍수관리에 어려움을 겪기도 한다. 그러나 최근 가뭄발생이 잦아 우리나라 전역에 가뭄피해가 발생하고 있으며 또한, 홍수기에도 많은 강우가 내리지 않아 2013년 이후에는 수문방류 실적이 전무한 편이다. 홍수로 인한 재해는 인명피해 및 재산피해를 동반하는 우리나라에서 가장 심각한 재해중의 하나이며, 재해예방을 위한 홍수예보는 강우예측과 유출해석으로 나뉠 수 있다. 강우예측은 정교한 강우모형과 기상전문가의 몫이며, 정확한 유출해석은 수문학자들에 의한 연구과제였다. 우리나라 홍수유출해석에 주로 사용되는 모형은 저류함수법이며, 1961년 일본의 Kimura에 의해 창안된 이래 여러 학자들에 의한 다각도의 모형개선을 통해 수차례 모형 성능 향상이 되었다. 그동안 축적된 홍수수문자료를 바탕으로 대청댐 준공이후 수문방류기간중 강우량-강우분포-유출율 관계를 통해 강우량별, 강우분포별, 매개변수별, 유출율, 홍수조절율에 대한 통계분석 및 상관분석을 시행하여 향후 발생가능한 홍수관련 업무에 활용하고자 한다. 또한, 수문방류기간중 호우원인(장마전선, 태풍, 국지성홍수 등)에 대한 분석을 시행하고 호우사상별 매개변수를 산정하여 해당 호우에 대한 특성을 파악하고자 한다.