• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.3
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• pp.43-56
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• 1982

A recursive algorithms for prediction of streamflows by Kalman filtering theory and Self-tuning predictor based on the state space description of the dynamic systems have been studied and the applicabilities of the algorithms to the rainfall-runoff processes have been investigated. For the representation of the dynamics of the processes, a low-order ARMA process has been taken as the linear discrete time system with white Gaussian disturbances. The state vector in the prediction model formulated by a random walk process. The model structures have been determined by a statistical analysis for residuals of the observed and predicted streamflows. For the verification of the prediction algorithms developed here, the observed historical data of the hourly rainfall and streamflows were used. The numerical studies shows that Kalman filtering theory has better performance than the Self-tuning predictor for system identification and prediction in rainfall-runoff processes.

• Journal of Korea Water Resources Association
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• v.51 no.5
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• pp.383-393
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• 2018

The regional frequency analysis is the method which uses not only sample of target station but also sample of neighborhood stations in which are classified as hydrological homogeneous regions. Consequently, identification of homogeneous regions is a very important process in regional frequency analysis. In this study, homogeneous regions for regional frequency analysis of precipitation were identified by the self-organizing map (SOM) which is one of the artificial neural network. Geographical information and hourly rainfall data set were used in order to perform the SOM. Quantization error and topographic error were computed for identifying the optimal SOM map. As a result, the SOM model organized by $7{\times}6$ array with 42 nodes was selected and the selected stations were classified into 6 clusters for rainfall regional frequency analysis. According to results of the heterogeneity measure, all 6 clusters were identified as homogeneous regions and showed more homogeneous regions compared with the result of previous study.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.4
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• pp.52-65
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• 1984

In general precise estimation of hourly of daily distribution of the long-term run-off should be very important in a design of source of irrigation. However, there have not been a satisfying method for forecasting of stationar'y long-term run-off in Korea. Solving this problem, this study introduces unit-hydrograph method frequently used in short-term run-off analysis into the long-term run-off analysis, of which model basin was selected to be Sumgin-river catchment area. In the estimation of effective rainfall, conventional method neglects the Soil moisture condition of catchment area, but in this study, the initial discharge (qb) occurred just before rising phase of the hydrograph was selected as the index of a basin soil moisture condition and then introduced as 3rd variable in the analysis of the reationship between cumulative rainfall and cumulative loss of rainfall, which built a new type of separation method of effective rainfall. In next step, in order to normalize significant potential error included in hydrological data, especially in vast catchment area, Snyder's correlation method was applied. A key to solution in this study is multiple correlation method or multiple regressional analysis, which is primarily based on the method of least squres and which is solved by the form of systems of linear equations. And for verification of the change of characteristics of unit hydrograph according to the variation of a various kind of hydrological charateristics (for example, precipitation, tree cover, soil condition, etc),seasonal unit hydrograph models of dry season(autumn, winter), semi-dry season (spring), rainy season (summer) were made respectively. The results obtained in this study were summarized as follows; 1.During the test period of 1966-1971, effective rainfall was estimated for the total 114 run-off hydrograph. From this estimation results, relative error of estimation to the ovservation value was 6%, -which is mush smaller than 12% of the error of conventional method. 2.During the test period, daily distribution of long-term run-off discharge was estimated by the unit hydrograph model. From this estimation results, relative error of estimation by the application of standard unit hydrograph model was 12%. When estimating by each seasonal unit bydrograph model, the relative error was 14% during dry season 10% during semi-dry season and 7% during rainy season, which is much smaller than 37% of conventional method. Summing up the analysis results obtained above, it is convinced that qb-index method of this study for the estimation of effective rainfall be preciser than any other method developed before. Because even recently no method has been developed for the estimation of daily distribution of long-term run-off dicharge, therefore estimation value by unit hydrograph model was only compared with that due to kaziyama method which estimates monthly run-off discharge. However this method due to this study turns out to have high accuracy. If specially mentioned from the results of this study, there is no need to use each seasonal unit hydrograph model separately except the case of semi-dry season. The author hopes to analyze the latter case in future sudies.

• Journal of Korea Water Resources Association
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• v.44 no.1
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• pp.51-64
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• 2011

The objective of this study is to develop a continuous rainfall-runoff model for flood prediction on a large-scale basin. For this study, the hourly surface runoff estimation method based on the variable retention parameter and runoff curve number is developed. This model is composed that the soil moisture to continuous rainfall can be simulated with applying the hydrologic components to the continuous equation for soil moisture. The runoff can be simulated by linking the hydrologic components with the storage function model continuously. The runoff simulation to large basins can be performed by using channel storage function model. Nakdong river basin is selected as the study area. The model accuracy is evaluated at the 8 measurement sites during flood season in 2006 (calibration period) and 2007~2008 (verification period). The calibrated model simulations are well fitted to the observations. Nash and Sutcliffe model efficiencies in the calibration and verification periods exist in the range of 0.81 to 0.95 and 0.70 to 0.94, respectively. The behavior of soil moisture depending on the rainfall and the annual loadings of simulated hydrologic components are rational. From this results, continuous rainfall-runoff model developed in this study can be used to predict the discharge on large basins.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.311-317
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• 1998

Recently irrigation reservoir has been developed to perform multipurpose function. To get a maximum effect it requires to establish optimal management system for irrigation reservoir in drought and flood season. Especially we dealt with optimal flood control system for irrigation reservoir in this study. This system consists of real-time rainfall data via online system, real-time flood forecasted by SCS method in hourly basis, storage volume by water balance equation, optimal releasing discharge from the gate, the water level in right downstream, and calculation of innundated area, depth, and time using GIS, and amount of flood damages. If we consider the relation of these sub module reasonably, we can reach the optimal flood control to minimize flood damage

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.202-206
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• 1994

Mathematical model of the pollution rate of substation insulators is constructed, taking the model parameters as wind speed, wind direction, typhoon conditions and rainfall in an hourly basis. The main feature of model construction is to distinguish the effect of each parameter by separately analyzing the positive and negative pollution causing factors. Model parameters for the insulators of Karatsu substation, Saga, Japan were estimated and model validation was done using the actual data, in which the pollution deposits on the insulators were measured using pilot insulator and 'salt meter'. The proposed model of the pollution rate [mg/cm$^{2}$/hr] enables the identification of the effective parameters and prediction of the pollution rate so that it helps for the automatic decision making for insulator cleaning or the model can be used as a tool for the substation engineers to make precautionary measures.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1332-1336
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• 2010

우리나라는 여름철의 큰 호우로 인해 피해가 빈번하게 발생하며, 이러한 호우는 주로 태풍과 집중호우로 인해 발생한다. 그런데 기후변화에 따른 이상기후로 인하여 이러한 호우사상들의 규모가 점차 커지고 있으며 그 특성 또한 변화하고 있는 추세이다. 따라서 본 연구에서는 우리나라 기상청에서 관할하는 총 78개의 기상 관측소 중에서 17개의 기상관측소를 대상으로 연최대시간강우량을 추출하여 각각의 지속시간에 대한 평균과 표준편차에 대한 변동성과 경향성에 대한 분석을 수행하였다. 또 호우의 원인을 태풍과 집중호우로 구분하여 각각의 지속시간별 연최대시간강우량을 구분하여 추출하고 이를 비교 분석하였다. 분석결과에서 연최대시간 강우량은 변동성이 있지만 경향성은 나타나지 않는 것으로 분석되었고, 지역에 따라 호우원인별 강우특성이 다르게 나타났다. 본 연구 결과를 기후변화에 따른 강우패턴의 변화를 예측하는데 있어 기초자료로 활용할 수 있고, 또 수공구조물의 설계에 반영한다면 호우로 인한 피해를 감소시킬 수 있는 것으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.345-345
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• 2012

정상성 기반의 전통적 극한치 이론은 기후변화 및 변동에 의한 외부변화 요인을 반영하기에는 한계가 있음이 지적되어왔다. 따라서 강우의 빈도분석 시 매개변수의 시간에 따른 변화를 반영한 비정상성 빈도분석 방법이 필요하다. 본 연구에서는 미호천 유역의 강우관측소 중 기상청에서 관리하는 청주 관측소 및 국토해양부에서 관리하는 가덕, 병천, 증평, 진천 관측소의 24시간 연최대치 강우자료를 대상으로 시간에 따른 경향성 분석을 하였다. 또한 자료의 경향성을 고려하여 비정상성 빈도분석을 하였고 외부상관기상변수로써 ENSO(El Nino Southern Oscillation)를 이용하여 비정상성 빈도분석을 실시하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.216-216
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• 2019

최근 이상 기후로 인하여 홍수피해가 많이 발생 하고 있다. 특히 도시유역의 도시화로 인해 불투수면적이 증가하여 내수 침수도 증가하였다. 이로 인하여 재산피해와 인명피해가 증가하면서 전 세계적으로 홍수 저감 연구가 진행 되고 있다. 강우의 시 공간적인 특성을 파악 하여 강우 사상을 정의 한다면 도시홍수 저감 에 있어 도움이 될 것이라 판단된다. 우리나라 서울 지역의 설계 강우량을 산정하기 위해 서울기상청에서 제공하고 있는 ASOS(Automated Surface Observing System) 를 사용해 왔다. 하지만 ASOS을 사용하게 되면 강수량의 공간 특성을 고려하기 어렵지만 AWS(Automatic Weather Stations) 는 세밀한 관측망을 가지고 있어 공간적 특성을 고려할 수 있다. 본 연구에서는 서울 기상청에서 제공하고 있는 강우 자료의 20개년 연속된 강우자료를 통해 강우자료를 구축 하였다. 서울지역의 유역을 선정하였으며 도시유역 강우-유출 해석에 많이 사용되는 EPA-SWMM 모형에 ASOS 와 AWS 강우자료를 적용하여 유출 분석을 하였다. 이러한 자료를 바탕으로 공간 특성 분석을 실시하여 더욱 세밀한 설계 강우량 산정에 도움을 있을 것으로 판단된다.

• Journal of Korean Society of Forest Science
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• v.88 no.4
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• pp.477-484
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• 1999

This study was conducted to investigate the effect of forest road on the suspended sediment yield into a stream in the small forest watershed. The samples of suspended sediment yield were collected at surveying points A and B in mountains watersheds unaffected by forest road, and at surveying point C affected by forest road. When hourly change of suspended sediment concentration was investigated, it showed the highest increase along the forest road, and the peak of suspended sediment concentration due to the watershed characteristics of each surveying point occurred before or at the same time with, the peak of discharge. This may be due to the time lag in which stagnated unstable suspended sediment moved strongly upon rainfall. Although suspended sediment load varied depending upon rainfall factors and surveying period, suspended sediment load per unit watershed flowed out 4.1 times more at the point C than at the point A and B. The suspended sediment load on 18~19 September, 1998, strongly affected by rainfall factors, was 4.179g/sec/㏊ at the point C, and 0.343g/sec/㏊ and 0.147g/sec/㏊ at the point A and B, respectively. This load was 12 times higher at the point C than at the point A and 28 times higher than at the point B.