Heechan Han

Dr. Heechan Han


Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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26 December 2019 in Water
Verified
Journal Article
Open access
PDF file
CCChanghyun Choi
Changhyun Choi
JKJungwook Kim
Jungwook Kim
HHHeechan Han
Heechan Han
DHDaegun Han
Daegun Han
Hung Soo KimHung Soo Kim
Hung Soo Kim
Wetlands play a vital role in hydrologic and ecologic communities. Since there are few studies conducted for wetland water level prediction due to the unavailability of data, this study developed a water level prediction model using various machine learning models such as artificial neural network (ANN), decision tree (DT), random forest (RF), and support vector machine (SVM). The Upo wetland, which is the largest inland wetland in South Korea, was selected as the study area. The daily water level gauge data from 2009 to 2015 were used as dependent variables, while the meteorological data and upstream water level gauge data were used as independent variables. Predictive performance evaluation using RF as the final model revealed 0.96 value for correlation coefficient (CC), 0.92 for Nash–Sutcliffe efficiency (NSE), 0.09 for root mean square error (RMSE), and 0.19 for persistence index (PI). The results indicate that the water level of the Upo wetland was well predicted, showing superior results compared to that of the ANN, which was used in a previous study. The results intend to provide basic data for development of a wetland management method, using water levels of previously ungauged areas.

1 October 2020 in CATENA
Verified
Journal Article
Closed access
JKJungho Kim
Jungho Kim
HHHeechan Han
Heechan Han
BKBoran Kim
Boran Kim
HCHaonan Chen
Haonan Chen
JLJai-Hong Lee
Jai-Hong Lee

8 February 2021 in Water
Verified
Journal Article
Open access
PDF file
HHHeechan Han
Heechan Han
CCChanghyun Choi
Changhyun Choi
JJJaewon Jung
Jaewon Jung
Hung Soo KimHung Soo Kim
Hung Soo Kim
Accurate runoff prediction is one of the important tasks in various fields such as agriculture, hydrology, and environmental studies. Recently, with massive improvements of computational system and hardware, the deep learning-based approach has recently been applied for more accurate runoff prediction. In this study, the long short-term memory model with sequence-to-sequence structure was applied for hourly runoff predictions from 2015 to 2019 in the Russian River basin, California, USA. The proposed model was used to predict hourly runoff with lead time of 1–6 h using runoff data observed at upstream stations. The model was evaluated in terms of event-based performance using the statistical metrics including root mean square error, Nash-Sutcliffe Efficiency, peak runoff error, and peak time error. The results show that proposed model outperforms support vector machine and conventional long short-term memory models. In addition, the model has the best predictive ability for runoff events, which means that it can be effective for developing short-term flood forecasting and warning systems. The results of this study demonstrate that the deep learning-based approach for hourly runoff forecasting has high predictive power and sequence-to-sequence structure is effective method to improve the prediction results.

1 October 2019 in Journal of Hydrology
Verified
Journal Article
Closed access
JKJungho Kim
Jungho Kim
HHHeechan Han
Heechan Han
LJLynn E. Johnson
Lynn E. Johnson
SLSanghun Lim
Sanghun Lim
RCRob Cifelli
Rob Cifelli

9 May 2022 in Water
Verified
Journal Article
Open access
PDF file
JKJongsung Kim
Jongsung Kim
HLHaneul Lee
Haneul Lee
MLMyungjin Lee
Myungjin Lee
HHHeechan Han
Heechan Han
DKDonghyun Kim
Donghyun Kim
Hung Soo KimHung Soo Kim
Hung Soo Kim
The importance of efficient water resource supply has been acknowledged, and it is essential to predict short-term water consumption in the future. Recently, it has become possible to obtain data on water consumption at the household level through smart water meters. The pattern of these data is nonlinear due to various factors related to human activities, such as holidays and weather. However, it is difficult to accurately predict household water consumption with a nonlinear pattern with the autoregressive integrated moving average (ARIMA) model, a traditional time series prediction model. Thus, this study used a deep learning-based long short-term memory (LSTM) approach to develop a water consumption prediction model for each customer. The proposed model considers several variables to learn nonlinear water consumption patterns. We developed an ARIMA model and an LSTM model in the training dataset for customers with four different water-use types (detached houses, apartment, restaurant, and elementary school). The performances of the two models were evaluated using a test dataset that was not used for model learning. The LSTM model outperformed the ARIMA model in all households (correlation coefficient: mean 89% and root mean square error: mean 5.60 m3). Therefore, it is expected that the proposed model can predict customer-specific water consumption at the household level depending on the type of use.

18 September 2021 in Water
Verified
Journal Article
Open access
PDF file
HHHeechan Han
Heechan Han
CCChanghyun Choi
Changhyun Choi
JKJongsung Kim
Jongsung Kim
Ryan R. MorrisonRyan R. Morrison
Ryan R. Morrison
JJJaewon Jung
Jaewon Jung
Hung Soo KimHung Soo Kim
Hung Soo Kim
Accurate prediction of soil moisture is important yet challenging in various disciplines, such as agricultural systems, hydrology studies, and ecosystems studies. However, many data-driven models are being used to simulate and predict soil moisture at only a single depth. To predict soil moisture at various soil depths with depths of 100, 200, 500, and 1000 mm from the surface, based on the weather and soil characteristic data, this study designed two data-driven models: artificial neural networks and long short-term memory models. The developed models are applied to predict daily soil moisture up to 6 days ahead at four depths in the Eagle Lake Observatory in California, USA. The overall results showed that the long short-term memory model provides better predictive performance than the artificial neural network model for all depths. The root mean square error of the predicted soil moisture from both models is lower than 2.0, and the correlation coefficient is 0.80–0.97 for the artificial neural network model and 0.90–0.98 for the long short-term memory model. In addition, monthly based evaluation results showed that soil moisture predicted from the data-driven models is highly useful for analyzing the effects on the water cycle during the wet season as well as dry seasons. The prediction results can be used as basic data for numerous fields such as hydrological study, agricultural study, and environment, respectively.