• Title/Summary/Keyword: parameter calibration

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Evaluation on applicability of on/off-line parameter calibration techniques in rainfall-runoff modeling (온·오프라인 매개변수 보정기법에 따른 강우-유출해석 적용성 평가)

  • Lee, Dae Eop;Kim, Yeon Su;Yu, Wan Sik;Lee, Gi Ha
    • Journal of Korea Water Resources Association
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    • v.50 no.4
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    • pp.241-252
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    • 2017
  • This study aims to evaluate applicability of both online and offline parameter calibration techniques on rainfall-runoff modeling using a conceptual lumped hydrologic model. To achieve the goal, the storage function model was selected and then two different automatic calibration techniques: SCE-UA (offline method) and particle filter (online method) were applied to calibrate the optimal parameter sets for 9 rainfall events in the Cheoncheon catchment, upper area of the Yongdam multi-purpose dam. In order to assess reproducibility of hydrographs from the parameter sets of both techniques, the observed discharge of each event was divided into low flow (below average flow) and high flow (over average flow). The results show that the particle filter method, updating the parameters in real-time, provides more stable reproducibility than the SCE-UA method regardless of low and high flow. The optimal parameters estimated by SCE-UA are very sensitive to the selected objective functions used in this study: RMSE and HMLE. In particular, the parameter sets from RMSE and HMLE demonstrate superior goodness-of-fit values for high flow and low flow periods, respectively.

Comparison of the Weather Station Networks Used for the Estimation of the Cultivar Parameters of the CERES-Rice Model in Korea (CERES-Rice 모형의 품종 모수 추정을 위한 국내 기상관측망 비교)

  • Hyun, Shinwoo;Kim, Tae Kyung;Kim, Kwang Soo
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.23 no.2
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    • pp.122-133
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    • 2021
  • Cultivar parameter calibration can be affected by the reliability of the input data to a crop growth model. In South Korea, two sets of weather stations, which are included in the automated synoptic observing system (ASOS) or the automatic weather system (AWS), are available for preparation of the weather input data. The objectives of this study were to estimate the cultivar parameter using those sets of weather data and to compare the uncertainty of these parameters. The cultivar parameters of CERES-Rice model for Shindongjin cultivar was calibrated using the weather data measured at the weather stations included in either ASO S or AWS. The observation data of crop growth and management at the experiment farms were retrieved from the report of new cultivar development and research published by Rural Development Administration. The weather stations were chosen to be the nearest neighbor to the experiment farms where crop data were collected. The Generalized Likelihood Uncertainty Estimation (GLUE) method was used to calibrate the cultivar parameters for 100 times, which resulted in the distribution of parameter values. O n average, the errors of the heading date decreased by one day when the weather input data were obtained from the weather stations included in AWS compared with ASO S. In particular, reduction of the estimation error was observed even when the distance between the experiment farm and the ASOS stations was about 15 km. These results suggest that the use of the AWS stations would improve the reliability and applicability of the crop growth models for decision support as well as parameter calibration.

Analysis of Characteristics of the Dynamic Flow-Density Relation and its Application to Traffic Flow Models (동적 교통량-밀도 관계의 특성 분석과 교통류 모형으로의 응용)

  • Kim, Young-Ho;Lee, Si-Bok
    • Journal of Korean Society of Transportation
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    • v.22 no.3 s.74
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    • pp.179-201
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    • 2004
  • Online traffic flow modeling is attracting more attention due to intelligent transport systems and technologies. The flow-density relation plays an important role in traffic flow modeling and provides a basic way to illustrate traffic flow behavior under different traffic flow and traffic density conditions. Until now the research effort has focused mainly on the shape of the relation. The time series of the relation has not been identified clearly, even though the time series of the relation reflects the upstream/downstream traffic conditions and should be considered in the traffic flow modeling. In this paper the flow-density relation is analyzed dynamically and interpreted as a states diagram. The dynamic flow-density relation is quantified by applying fuzzy logic. The quantified dynamic flow-density relation builds the basis for online application of a macroscopic traffic flow model. The new approach to online modeling of traffic flow applying the dynamic flow-density relation alleviates parameter calibration problems stemming from the static flow-density relation.

Parameter Calibration and Estimation for SSARR Model for Predicting Flood Hydrograph in Miho Stream (미호천유역 홍수모의 예측을 위한 SSARR 모형의 매개변수 보정 및 추정)

  • Lee, Myungjin;Kim, Bumjun;Kim, Jongsung;Kim, Duckhwan;Lee, Dong ryul;Kim, Hung Soo
    • Journal of Wetlands Research
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    • v.19 no.4
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    • pp.423-432
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    • 2017
  • This study used SSARR model to predict the flood hydrograph for the Miho stream in the Geum river basin. First, we performed the sensitivity analysis on the parameters of SSARR model to know the characteristics of the parameters and set the range. For the parameter calibration, optimization methods such as genetic algorithm, pattern search and SCE-UA were used. WSSR and SSR were applied as objective functions, and the results of optimization method and objective function were compared and analyzed. As a result of this study, flood prediction was most accurate when using pattern search as an optimization method and WSSR as an objective function. If the parameters are optimized based on the results of this study, it can be helpful for decision making such as flood prediction and flood warning.

Calibration and Estimation of Parameter for Storage Function Model (저류함수모형의 매개변수 보정 및 추정)

  • Kim, Bum Jun;Kawk, Jae Won;Lee, Jin Hee;Kim, Hung Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.1B
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    • pp.21-32
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    • 2008
  • Flood forecasting is a very important tool as one of nonstructural measures for reduction of flood damages in life and property and its accuracy is also an important factor. However, when we apply the Storage Function Model(SFM) which is mainly used for the flood forecasting system in Korea, the determination of the parameters is very important but it is difficult. So, the parameters have been calibrated by using an empirical formulas and judgement of hydrologist. Hence, in this study we perform the sensitivity analysis to understand the parameter characteristics and establish the ranges of parameters of the SFM. Also we do the parameter calibration by using the optimization techniques and objective functions, and evaluate their performances. Especially, we suggest a method to determine proper parameters by using a objective function which can be obtained from flood events. So, we use the suggested method for parameter estimation and compare the estimated parameters with the previously reported parameters. As a result of the application, the estimated parameters by the suggested method showed better than them from the previously reported parameters.

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OPTIMAL DESIGN AND FABRICATION OF SPIRAL INDUCTOR ON SILICON SUBSTRATE (실리콘 기판상에서 나선형 인덕터의 최적설계 및 제작)

  • 서종삼;박종욱이성희김영석
    • Proceedings of the IEEK Conference
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    • 1998.10a
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    • pp.645-648
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    • 1998
  • We used a three-dimensional inductance extraction program, Fasthenry for optimal design of the spiral inductors on silicon substrate. The inductance and quality factor of the spiral inductors with various design parameters were calculated so that the optimal parameter value was determined. The spiral inductors then were fabricated using different foundary processes and were measured using the network analyzer and microwave probes. The pad and other parasitics of measurement system were de-embedded using the y-parameter calibration technique. the inductors fabricated using the LG 0.8um process and HP 0.5um process showed the quality factor of 5.8 and 3, respectively. Finally the equivalent circuit farameters of the spiral inductors on silicon substrate were extracted from the measurement data using the matlab.

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Comparative Study on Calibration Methods for Parameter Calibration of Storage Function Model (저류함수모형의 매개변수 보정을 위한 보정기법 비교 연구)

  • Kim, Bum-Jun;Kim, Jae-Hyun;Kwak, Jae-Won;Kim, Hung-Soo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2006.05a
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    • pp.1140-1144
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    • 2006
  • 홍수를 예측하기 위해서 국내 5대강 유역의 홍수통제소는 저류함수모형을 사용하고 있다. 그러나 저류함수모형을 실제 홍수사상에 적용하기 위해 매개변수를 결정하여야 하는데 이는 매우 어려운 작업으로 지금까지는 저류함수모형의 매개변수 보정을 위해 시행착오에 의한 수동보정 방법을 사용하여 왔다. 이에 본 연구는 미호천 유역을 대상유역으로 하여 Pattern Search Multi-Start(P-S), SCE-UA와 유전자 알고리즘(GA)을 이용하여 매개변수 보정을 하고, 그 방법들에 대한 비교와 분석을 하였다. 그리고 최적화 기법을 통해 얻어진 매개변수를 사용하여 저류함수모형의 홍수수문곡선을 유도하고 이를 비교, 분석하였다. 또한 SSR과 WSSR의 목적함수를 사용하여 목적함수별 홍수수문곡선을 비교, 분석하였다.

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Illumination Invariant Ranging Sensor Based on Structured Light Image (조명잡음에 강인한 구조광 영상기반 거리측정 센서)

  • Shin, Jin;Yi, Soo-Yeong
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.12
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    • pp.122-130
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    • 2010
  • This paper presents an active ranging system based on laser structured-light image. The structured-light image processing is computationally efficient in comparison with the conventional stereo image processing, since the burdensome correspondence problem is avoidable. In order to achieve robustness against environmental illumination noise, an efficient image processing algorithm, i.e., integration of difference images with structured-light modulation is proposed. Distance equation from the measured structured light pixel distance and system parameter calibration are addressed in this paper. Experiments and analysis are carried out to verify performance of the proposed ranging system.

Virtual Space Calibration for Laser Vision Sensor Using Circular Jig (원형 지그를 이용한 레이저-비젼 센서의 가상 공간 교정에 관한 연구)

  • 김진대;조영식;이재원
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.12
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    • pp.73-79
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    • 2003
  • Recently, the tole-robot operations to an unstructured environment have been widely researched. The human's interaction with the tole-robot system can be used to improve robot operation and performance for an unknown environment. The exact modeling based on real environment is fundamental and important process for this interaction. In this paper, we propose an extrinsic parameter calibration and data augmentation method that only uses a circular jig in the hand-eye laser virtual environment. Compared to other methods, easier estimation and overlay can be done by this algorithm. Experimental results using synthetic graphic demonstrate the usefulness of the proposed algorithm.

Real-time position measurements of mobile object using PSD sensor (PSD 센서를 이용한 이동물체의 실시간 위치측정)

  • Ro, Jae-Hee;Kweon, Seok-Geon;Seo, Nam-Il;Ro, Young-Shick
    • Proceedings of the KIEE Conference
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    • 1998.11b
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    • pp.540-542
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    • 1998
  • The Position Sensitive Detector(PSD) is an useful device which can be used to measure the position of an incidence light in accuracy and in real-time. In this paper, 2-D PSD sensor is used to measure the 2-D position of moving object with light source. To get the position of light source from PSD sensor exactly, we propose two position computation methods ; the parameter calibration and neural network. Experimental data is presented that offer the comparision between two methods and demonstrates the effectiveness of proposed approach.

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