• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6B
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• pp.709-721
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• 2008

This paper is to test the applicability of ModKIMSTORM (Modified KIneMatic Wave STOrm Runoff Model) by applying it to Namgangdam watershed of $2,293km^2$. Model inputs (DEM, land use, soil related information) were prepared in 500 m spatial resolution. Using five typhoon events (Saomi in 2000, Rusa in 2002, Maemi in 2003, Megi in 2004 and Ewiniar in 2006) and two storm events (May of 2003 and July of 2004), the model was calibrated and verified by comparing the simulated streamflow with the observed one at the outlet of the watershed. The Pearson's coefficient of determination $R^2$, Nash and Sutcliffe model efficiency E, the deviation of runoff volumes $D_v$, relative error of the peak runoff rate $EQ_p$, and absolute error of the time to peak runoff $ET_p$ showed the average value of 0.984, 0.981, 3.63%, 0.003, and 0.48 hr for 4 storms calibration and 0.937, 0.895, 8.08%, 0.138, and 0.73 hr for 3 storms verification respectively. Among the model parameters, the stream Manning's roughness coefficient was the most sensitive for peak runoff and the initial soil moisture content was highly sensitive for runoff volume fitting. We could look into the behavior of hyrologic components from the spatial results during the storm periods and get some clue for the watershed management by storms.

• Journal of Korean Society of Disaster and Security
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• v.16 no.2
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• pp.49-56
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• 2023

Impact based forecast refers to providing information on potential socioeconomic risks according to weather conditions, away from the existing weather factor-oriented forecast. Developed weather countries are investing manpower and finances in technology development to provide and spread impact information, but awareness of impact based forecasts has not spread in Korea. In addition, the focus is on disasters such as floods and typhoons, which cause a lot of damage to impact based forecasts, and research on evaluating the impact of vehicle risks due to strong winds in the transportation sector with relatively low damage is insufficient. In Korea, there are not many cases of damage to vehicle conduction caused by strong winds, but there are cases of damage and the need for research is increasing. Road vulnerability is required to evaluate the risk of vehicles caused by strong winds, and the purpose of this study was to calculate the criteria for road vulnerability. The road vulnerability evaluation was evaluated by the altitude of the road, the number of lanes, the type of road. As a result of the analysis, it was found that the vulnerable area was well reproduced. It is judged that the results of this study can be used as a criterion for preparing an objective evaluation of potential risks for vehicle drivers.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.37 no.2
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• pp.20-29
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• 2019

The purpose of this study is to verify and reconstruct the record information for big old trees of Jeju on the basis of the precise map of Jeju island in 1918 which was produced 100 years ago. For the analysis of high altitude, coordinate system and georeferencing were performed by selecting representative points using ArcGIS. We extracted digitized information by using point extraction method and extracted attribute information based on legend type and relative size in map. Based on the map of the past 100 years ago, the present situation of the big old tree in Jeju was analyzed and their characteristics were analyzed. In addition, based on the information of the protected big old trees in present, we discussed the characteristics of past tree (1918), present tree (2019), and contribution of big old tree in Jeju landscape and vegetation. As a result, 1,013 individuals were distributed in Jeju Island 100 years ago. Even when it was intensive in the use of timber, the big old trees were protected, and contributed as a representative component of Jeju's unique landscape. The remaining distribution of Jeju's big old tree is 159 trees. As in the past, distribution has been confirmed around the lowlands, but declines in numbers are found throughout the island. The major factors for the decline of individuals are large-scale development projects such as reaching the limit of life, natural disturbance (typhoon, disease, pest, drought, etc.). However, it is presumed that a large number of individuals have played a leading role in shaping the current forests as contributing to important species sources in the restoration process of Jeju vegetation. However, it is presumed that a large number of individuals (405) have played a leading role in forming the present forest by contributing to the species pool in the restoration process of Jeju vegetation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.3
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• pp.113-123
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• 2008

We have analyzed a long term data of marine environments, red tide information and meteorology acquired by NFRDI and KMA, in order to understand the characteristics of marine environments in the Narodo coastal waters which is known to be the first outbreak region of Cochlodinium polykrikoides blooms. During the period of from 1992 to 2007, Cochlodinium polykrikoides blooms have first occurred more often in August. However, the outbreak time of the blooms tended to be earlier annually, and in addition, the surface salinity also had a tendency to increase. Consequently, it suggested that there might be a relationship between the transition of the outbreak time of the blooms and salinity. On the other hand, insolation was relatively rich but precipitation was relatively scarce in Gohung Province, compared to Yeosu or Tongyeong, when Cochlodinium polykrikoides blooms first occur in Narodo coastal waters. Average water temperature and salinity in August in Narodo coastal waters were all higher than those in Gamak and Jinhae bays, suggesting that Narodo coastal waters are a region of relatively high water temperature and high salinity. Also, concentrations of nutrients and chlorophyll- a were significantly low than those in Jinhae Bay, which is known to be a eutrophicated region, while the overall water quality seemed to be similar to Gamak Bay. The results of PCA(Principal Component Analysis) proved that insolation and water temperature are the most important factors for the outbreak of Cochlodinium polykrikoides blooms in Narodo coastal waters while concentrations of COD and dissolved oxygen are secondly important. Furthermore, typhoons also appeared to be one of most important factors for the outbreak of Cochlodinium polykrikoides blooms.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.135-135
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• 2011

지구온난화와 이상기후에 따라 최근 우리나라를 둘러싼 기후패턴의 변화가 가속화되고 있으며 한반도는 장마기간이 소강상태를 보이는 반면, 장마 후 국지성 집중호우가 증가하고 태풍이 내습하는 현상이 빈번해짐으로써 홍수에 대한 위험과 피해규모도 증가하고 있다. 특히 도시지역에서는 강우규모가 배수시스템의 용량을 초과하거나, 하천수위 상승으로 관로 내에 역류가 발생하는 등 우수 배제 기능을 제대로 수행하지 못할 경우 발생하는 지표침수로 인해 심각한 인명 및 재산피해가 발생하고 있다. 실제로 현재 홍수해석 및 홍수위험지도 작성시 내수시스템을 반영하지 않아 침수면적 및 범위의 오차가 존재하며 홍수위험지도 작성시 내수범람과 외수범람을 따로 고려하는 문제점이 있다. 따라서 도시 침수 해석시 내수시스템을 반영한 정확한 침수심 및 침수면적계산뿐만 아니라 이상기후에 대비한 복합적 요인으로 인한 침수해석이 필요하다. 따라서 본 연구에서는 하천해석을 위해 1차원 하천 해석 모형인 FLDWAV모형을 적용하고 가상의 제방 파제 시나리오를 통하여 외수범람 영향을 구하였으며, 배수시스템의 SWMM모형과 제내지에서 내수와 외수범람의 영향을 고려한 DEM기반의 2차원 범람해석을 연계한 Dual-Drainage모형에 대하여 외수범람 영향에 따른 흐름의 양상, 침수심, 침수위 등을 분석하였다. 개발한 모형에 대한 적용성을 검토하기 위하여 대구 신암5동 유역을 선정하였고 대상유역의 수치지도를 활용하여 정형 격자 20m 크기로 지형자료를 구성하였으며, 건물의 영향도 고려하기 위해 DEM에 건물자료를 합성하였다. 침수해석 결과 내수시스템의 영향을 고려하지 않을 때가 고려하였을 때 보다 Node(맨홀)에서의 재유입의 영향으로 인하여 최대 침수심이 더 높게 나왔으며 침수면적도 넓게 나타나는 것을 확인하였고, 기존의 홍수위험지도 작성시 외수침수와 내수침수를 구분하여 해석하였던 것을 본 연구에서 통합하여 외수범람의 영향을 고려한 통합침수해석을 실시하여 내수에서 발생할 수 있는 유출량과 내수시스템의 월류량 등에 대한 고려가 없는 외수침수만 해석시 보다 최대침수심이 더 높게 나타났으며 침수면적 또한 넓게 나타남을 알 수 있었다. 본 연구를 통해서 도시홍수, 돌발홍수 등의 발생시 정확한 도시 침수 해석이 가능하며 도시침수구역에 대한 적절한 예 경보 및 피난대책 수립에 활용될 수 있을 것으로 사료된다. 또한 국내의 홍수위험지도나 도시 침수해석과 연계하여 선행시간을 확보한 정확도 높은 홍수정보시스템 구축에 크게 기여할 것으로 판단된다.

• Journal of the Korea Institute of Building Construction
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• v.20 no.1
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• pp.83-91
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• 2020

The recent bridge construction projects is demanded more sophisticated risk management measures and loss forecasts to brace for risk losses from an increase in the trend of bridge construction. This study aims to analyze the risk factors that caused the loss of material in actual bridge construction and to develop a quantified predictive loss model, based on the past record of insurance payment by major domestic insurance companies for bridge construction projects. For the development of quantitative bridge construction loss model, the dependent variable was selected as the loss ratio, i.e., the ratio of insurance payout divided by the total project cost, while the independent variable adopted 1) Technical factors: superstructure type, foundation type, construction method, and bridge length 2) Natural hazards: typhoon and flood 3) Project information: construction period and total project cost. Among the selected independent variables, superstructure type, construction method, and project period were shown to affect the ratio of bridge construction losses. The results of this study can provide government agencies, bridge construction design and construction and insurance companies with the quantitative damage prediction and risk assessment services, using risk indicators and loss prediction functions derived from the findings of this study and can be used as a guideline for future basic bridge risk assessment development research.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.599-607
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• 2015

The purpose of this study is to reproduce long-term wave fields in coastal waters of Korea based on wave hind-casting modelling and discuss its applications. To validate wind data(NCEP, ECMWF, JMA-MSM), comparison of wind data was done with wave buoy data. JMA-MSM predicted wind data with high accuracy. But due to relatively longer period of ECMWF wind data as compared to that of JMA-MSM, wind data set of ECMWF(2001~2014) was used to perform wave hind-casting modelling. Results from numerical modelling were verified with the observed data of wave buoys installed by Korea Meteorological Administration(KMA) and Korea Hydrographic and Oceanographic Agency(KHOA) on offshore waters. The results agree well with observations at buoy stations, especially during the event periods such as a typhoon. Consequently, the wave data reproduced by wave hind-casting modelling was used to obtain missing data in wave observation buoys. The obtained missing data indicated underestimation of maximum wave height during the event period at some points of buoys. Reasons for such underestimation may be due to larger time interval and resolution of the input wind data, water depth and grid size etc. The methodology used in present study can be used to analyze coastal erosion data in conjunction with a wave characteristic of the event period in coastal areas. Additionally, the method can be used in the coastal disaster vulnerability assessment to generate wave points of interest.

• Journal of Korea Water Resources Association
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• v.45 no.7
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• pp.631-641
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• 2012

In this study, satellite data (MTSAT-1R), a numerical weather prediction model, RDAPS (Regional Data Assimilation and Prediction System) output, ground weather station data, and artificial neural networks were used to improve the accuracy of summer rainfall forecasts. The developed model was applied to the Seoul station to forecast the rainfall at 3, 6, 9, and 12-hour lead times. Also to reflect the different weather conditions during the summer season which is related to the frontal precipitation and the cyclonic precipitation such as Jangma and Typhoon, the neural network models were formed for two different periods of June-July and August-September respectively. The rainfall forecast model was trained during the summer season of 2006 and 2008 and was verified for that of 2009 based on the data availability. The results demonstrated that the model allows us to get the improved rainfall forecasts until lead time of 6 hour, but there is still a large room to improve the rainfall forecast skill.

• Journal of Korea Water Resources Association
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• v.42 no.3
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• pp.191-200
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• 2009

A localized torrential rainfall and flash floods which are more frequently occurred by extraordinary atmospheric phenomena and rising sea surface temperature require more hydrological data collecting and analysis for small watershed. Urban watershed hydrological data monitoring system is needed because of big flood potential damage and lack of urban watershed hydrological data. Therefore, Urban Flood Disaster Management Research Center operates small experimental catchments(Sinnae1, Gunja, and Children's Park) observing and analyzing hydrological data(rainfall, stage, and discharge). In this study, the discharge of combined sewage for Gunja experimental drainage is analyzed with weekly data and day of the week data. Through several analyses in analyzing the urban runoff characteristics and managing the urban sewage system, direct runoff is calibrated and verified by the estimated values of rainfall-runoff model(SWMM).

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.4
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• pp.211-217
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• 2004

The instrument used in this study consists of a lkg capacity loadcell and a Imm tipping bucket rain gauge. There are two signals: one is the weight of the water in the tipping bucket and the other is the pulse from the reversing mechanism of the tipping bucket. The loadcell measures the weight of water with a 0.0lmm resolution up to 1mm rainfall and the bucket reverses beyond 1mm. From this point, a pulse signal generates and the loadcell starts measuring the weight again. A field test was carried out with the range of rainfall intensity from 42mm/h to 250mm/h. The result shows an error range from -2.2% to + 2.6% in 12 measurement cases with a rainfall of l00mm or more. This result satisfies the WMO recommendation for rainfall intensity instrumentation which allows a 5% range. In a field experiment during 17 to 19 August, 2004, more than 100mm/h rainfall intensity was observed by this instrument, confirming that our instrument has a sufficient capacity of rainfall intensity measurement under extreme conditions like Jangma (Bai-u season). Compared with existing commercial models which employ a water drop measurement method, our method can give a practical solution for diagnostic check of remote rain gauges using two independent signals.