• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2018년도 학술발표회
• /
• pp.150-150
• /
• 2018

The Numerical Weather Prediction (NWP) models provide information for weather forecasts. The highly nonlinear and complex interactions in the atmosphere are simplified in meteorological models through approximations and parameterization. Therefore, the simplifications may lead to biases and errors in model results. Although the models have improved over time, the biased outputs of these models are still a matter of concern in meteorological and hydrological studies. Thus, bias removal is an essential step prior to using outputs of atmospheric models. The main idea of statistical bias correction methods is to develop a statistical relationship between modeled and observed variables over the same historical period. The Model Output Statistics (MOS) would be desirable to better match the real time forecast data with observation records. Statistical post-processing methods relate model outputs to the observed values at the sites of interest. In this study three methods are used to remove the possible biases of the real-time outputs of the Weather Research and Forecast (WRF) model in Imjin basin (North and South Korea). The post-processing techniques include the Linear Regression (LR), Linear Scaling (LS) and Power Scaling (PS) methods. The MOS techniques used in this study include three main steps: preprocessing of the historical data in training set, development of the equations, and application of the equations for the validation set. The expected results show the accuracy improvement of the real-time forecast data before and after bias correction. The comparison of the different methods will clarify the best method for the purpose of the forecast skill enhancement in a real-time case study.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2002년도 춘계학술대회 논문집
• /
• pp.6-11
• /
• 2002

A term of GNSS(Global Navigation Satellite System) is widely used to represent a navigation method for global area using satellite in space orbit 1his system can provide accurate and continuous position, and timing sources synchronized to UTC. There are, however, certain disadvantage that system can not operate without line of sight environment to satellite, or system failure of either satellite or control station. It is the pseduolite technology for using indoor and also for back-up equipment of foreign system failure. Especially, ocean applications widely use the GNSS system for navigation, surveying, timing, and management of traffic, so, system failure of GNSS will be very critical problem to affect many aspects of ocean field. In this paper, we experimented the pseudolite technology for several application field to compare the result in different environment. We used the common CDGPS algorithm for in-door navigation and experimented in ocean engineering basin with metallic wall and gymnasiums with concrete wall. We also investigated the comparison result and considerations for ocean applications of pseudolite technology.

• 대한조선학회논문집
• /
• 제41권2호
• /
• pp.1-11
• /
• 2004

In this paper, the resistance characteristics of high-speed ship are studied in the region of shallow water condition. For the purpose of this research, model tests in a ship model basin are carried out with an equipment for the satisfaction of shallow water condition, and the computions of wave resistance characteristics and the flow simulations around a ship hull are performed by Michell's thin ship theory and a finite difference method based on MAC scheme, respectively. The calculation results for the resistance and flow characteristics of a ship hull are compared with those from the model tests in deep and shallow water conditions. From the comparison results, it is known that the variation of wave pattern around a ship hull caused by shallow water condition has the most influence to the resistance characteristics of a high-speed ship advancing on shallow water.

• 한국방재학회 논문집
• /
• 제8권2호
• /
• pp.139-147
• /
• 2008

범람의 주요한 원인 중 하나인 하상변동의 경향을 정확히 예측하고 분석하는 것은 제방의 설계나 하천시설물의 설계에 있어 매우 중요하다고 할 수 있다. 이에 본 연구에서는 2차원 하상변동 모형인 SMS을 사용하여 해마다 게릴라성 호우로 인해 피해를 입고 있는 임진강의 지류인 포천천 유역에 대해 하상변동을 모의하였다. 지금까지 SMS 모형의 경우 우리나라의 하천구간에 대해 광범위하게 모형의 검증이 되어있지 않으므로 본 연구에서는 대상구간에 대해 86년 실측단면자료를 초기로 하여 장기하상변동을 모의하였으며, 모형의 결과를 98년 실측단면자료와 비교 분석함으로써 모형의 검증을 실시하였다. 모형의 검증결과 횡방향과 종방향의 하상고 변동의 비교에서 일부 국부적인 하상의 세굴을 제외하고는 SMS 모형의 모의결과가 실측치에 근사함을 알 수 있었다. 하지만, 정량적인 비교에서는 각 단면별로 98년 실측치보다 모형에 의한 계산치가 하상 변동량이 다소 과소로 산정 되었다.

• 한국수자원학회논문집
• /
• 제45권3호
• /
• pp.301-316
• /
• 2012

본 연구에서는 한강수계 팔당댐 상류의 자연유출량에 대해 기존의 연구 결과를 바탕으로 TANK 모형 결과와 SWAT 모형결과를 비교함으로써, 기존 TANK 모형이 가지고 있는 한계및 문제점을 현실적으로 제시하고, 향후 SWAT 모형의 적용성 및 활용에 대해 검토하였다. TANK 모형의 매개변수 최적화가 이루어진 보정유역들(충주댐 및 소양강댐)의 모의결과를 볼 때 두 모형 모두 모형효율 0.8 이상의 높은 정도의 모의가 가능한 것으로 나타났으며, 첨두유량이 발생하는 홍수기에는 TANK의 결과가 SWAT보다 관측치에 근접하는 것으로 나타났다. 그러나 TANK 모형의 경우 주로 평수기 이상의 유량을 대상으로 보정을 수행하여 갈수기에 관측유량과 많은 차이를 보였으며, 특히 일정 유량 이하로 모의되지 않는 한계를 나타내었다. 반면, SWAT 모형은 일부 홍수사상을 제외하고 대체로 관측치의 경향을 잘 따르고 있으며, 유역 최종 출구인 팔당댐(한강F)에서의 상류댐 방류량을 고려한 모의유입량이 실제 관측유입량과 잘 일치하는 것으로 나타나(모형효율 0.9 수준), 댐 방류량과 인위적인 용수 수요가 없는 상태의 자연유출량의 추정이나 댐개발 전후에 따른 유량변동 평가 등에 있어 매우 높은 신뢰성을 보장하는 것으로 판단되었다. 아울러, TANK 모형의 최적화된 매개변수를 전이시켜 이용하는 대상유역들(평창A, 달천B, 섬강B, 인북A, 한강D, 홍천A)에 대한 결과를 SWAT 모형 결과와 비교할 때, 일부 홍수기를 제외하고는 평수기 이하에서 매우 불안정한 모의 결과를 나타내었으며, 보정유역들에 대한 결과와 마찬가지로 갈수기에 일정 유량이하로 모의되지 않는 문제가 나타났다. 이는 수자원 계획 및 관리의중요한 지표인 갈수량의 산정에 있어 TANK 모형의 적용에 많은 불확실성이 있음을 보여준다. 따라서 복잡 다양한 국내 유역의 특성을 보다 현실적으로 반영하고, 향후 유역내 도시화 등에 따른 토지이용 및 용수이용의 변화, 기후변화 등에 따른 수자원 계획 및 관리에 효율적으로 대처하기 위해서는 TANK와 같은 기존의 개념적 집중형 모형보다는 SWAT과 같은 물리적 기반의 유역모형 적용이 필요할 것으로 판단된다.

• 지질공학
• /
• 제34권2호
• /
• pp.173-191
• /
• 2024

Landslides pose significant threats to many countries globally, yet the development and implementation of effective landslide early warning systems (LEWS) remain challenging due to multifaceted complexities spanning scientific, technological, and political domains. Addressing these challenges demands a holistic approach. Technologically, integrating thresholds, such as rainfall thresholds, with real-time data within accessible, open-source software stands as a promising solution for LEWS. This article introduces LandScient_EWS, a PHP-based program tailored to address this need. The software facilitates the comparison of real-time measured data, such as rainfall, with predefined landslide thresholds, enabling precise calculations and graphical representation of real-time landslide advisory levels across diverse spatial scales, including regional, basin, and hillslope levels. To illustrate its efficacy, the program was applied to a case study in Medellin, Colombia, where a rainfall event on August 26, 2008, triggered a shallow landslide. Through pre-defined rainfall intensity and duration thresholds, the software simulated advisory levels during the recorded rainfall event, utilizing data from a rain gauge positioned within a small watershed and a single grid cell (representing a hillslope) within that watershed. By identifying critical conditions that may lead to landslides in real-time scenarios, LandScient_EWS offers a new paradigm for assessing and responding to landslide hazards, thereby improving the efficiency and effectiveness of LEWS. The findings underscore the software's potential to streamline the integration of rainfall thresholds into both existing and future landslide early warning systems.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
• /
• pp.343-348
• /
• 1999

Delineation of watersheds is one of the most basic steps for water resource management and National Park management. The purpose of this study is to investigate how to utilize Thematic Mappers scenes to compare watersheds created by running a model with those produced by digitizing topographic maps of Keum River basin. A methodology is designed and tested using Geographic Information Systems (GIS) and remote sensing to map areas with various thematic maps. A CAD data on watersheds from the Decision Support system for Water Quality is converted into GIS format. The digital elevation model with 100-meter resolution is used to create watershed by cumulative watershed method. TM scenes are also classified by new procedures including stacking method, NDVI, NDWI, and unsupervised classification methods. To evaluate the relative correctness Kyerongsan National Park was studied intensively whose area was divided into 6 watersheds in both cases. The boundaries of watershed from the model are less correct than those of the topographic maps. This result shows that automated watershed creating system needs higher-resolution digital elevation model than 100-meters.

• 물과 미래
• /
• 제29권6호
• /
• pp.237-247
• /
• 1996

본 연구는 하천 수계에서의 홍수 유출 예측 정도를 높일 수 있는 방안을 도출하고자, 저류함수 모형과 NWS-PC모형을 선정하여 모형의 구조 및 특성을 분석하고 그 예측능력을 비교검토한 것이다. 저류함수 모형은 1974년도부터 우리나라에 도입되어 주요하천 홍수예경보 업무에 사용되어 왔으며, NWS-PC모형은 유역의 사면과 하도의 유출을 운동파로 모의하고 지표 또는 지하의 수문 과정도 토앙함수상태 계산 (SAC-SMA)을 통하여 모의하는 물리적 기반의 모형이다. 모형의 적용은 미호천 유역을 선정하였고, '85년-95년 동안의 홍수 자료를 이용하여 모형을 적용하고 곽측치에 대한 RMS오차와 첨두유량 및 총유출체적의 상대오차 등을 비교한 결과를 토대로 각각의 장단점 및 적용성을 밝히고, 개선방향 등을 제시하였다.

• 한국농공학회지
• /
• 제42권6호
• /
• pp.72-82
• /
• 2000

Many lot of books introduce the methods to calculate the time of concentration, and these are described as various forms of formulas. There are few formulas appropriate for our basin characteristics Therefone, there are problems to make excessive or less estimation when these formulas are used. To solve these problems, comparison of formulas and sensitivity analysis for them were made with converting parameters. Finally, Time of concentration was estimated to derive Application limits for 3 watersheds by standardized formulas. In the case of input parameters analysis, SCS formula has the highest value by the length, Kerby by the height and SCS by the slope, respectively, while Kraven formula has the lowest value among them. Concerning the relative sensitivity by Taylor series, the time of concentration showed the constant effect while increasing of the length and slope, and the length was more sensitive than the slope in parameters. Finally the standardization formula developed in this study was applied to derive application limits for 3 watersheds(total 17 subbasins). In this case, Rziha(8 subbasins) and SCS(9 subbasins) formulas were the most similar to observed data of total 17 subbasins respectively. Application limits were about 300~500$\textrm{km}^2$ area, 30~60km length and under 0.01 slope for Rziha formula and about 100~200$\textrm{km}^2$ area, 10~30km length, and over 0.01 slope for SCS formula, respectively.

• 대한조선학회논문집
• /
• 제43권1호
• /
• pp.1-14
• /
• 2006

To improve maritime safety, it is very important not only to make safer design and operation but also to do proper response in case of maritime casualty. The large-scaled casualties will be caused by loss of structural strength and stability due to the progressive flooding and enlargement of damage by the effect of waves and wind. To prevent foundering and structural failure, the prediction of ship motion behavior of damaged ship in wave is necessary. This paper describes the motion behavior of damaged ship in waves through theoretical and experimental studies. A time domain theoretical model of damaged ship motions and accidental flooding, which can be applied to any type of ship or arrangement and considers the effects of flooding of compartments, has been developed. The model tests have been carried out in regular and irregular waves with different wave heights and directions in ship motion basin. Those were performed for three different damaged conditions such as engine room bottom damage, side shell damage and bow visor damage of a Ro-Ro ship. Comparison of theoretical and experimental results was performed.