Donghyun Kim

Mr. Donghyun Kim

orcid

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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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.

2 November 2023 in Journal of Hydrology
Verified
Journal Article
Closed access
WWWon-Joon Wang
Won-Joon Wang
DKDonghyun Kim
Donghyun Kim
HHHeechan Han
Heechan Han
KKKyung Tak Kim
Kyung Tak Kim
SKSoojun Kim
Soojun Kim
Hung Soo KimHung Soo Kim
Hung Soo Kim

5 May 2023 in KSCE Journal of Civil Engineering
Verified
Journal Article
Open access
PDF file
DKDonghyun Kim
Donghyun Kim
JPJongpyo Park
Jongpyo Park
HHHeechan Han
Heechan Han
HLHaneul Lee
Haneul Lee
Hung Soo KimHung Soo Kim
Hung Soo Kim
SKSoojun Kim
Soojun Kim
Owing to global climate change, the frequency of disasters has increased twelve-fold, with a corresponding approximately seventeen-fold increase in economic damages over the past six decades. Notably, severe flood damage has been occurring in Asia along the Pacific coast due to extreme weather events, including torrential rains and typhoons, which have been becoming increasingly frequent and prolonging the rainy season. In the Eastern Visayas region, the management and monitoring facilities for flood observation data, as well as the forecasting and warning systems suitable for the local area, are insufficient. The warning system introduced through overseas grants is limited in operation in some areas of the city. Furthermore, although an organization has jurisdiction over flood forecasting and warning, the system’s operation is not systematic and is limited. Additionally, there is a shortage of technical manpower. In this study, we utilized deep learning models to forecast flood water levels in the CarayCaray Basin on Biliran Island, located in Eastern Visayas, the Philippines. Additionally, a flood risk classification was applied to evaluate the degree of risk associated with the predicted water levels. The predicted water levels for each model were compared with the observed water level data. The evaluation of the predictive performance of each model resulted in an NRMSE value of 9.48. Moreover, the accuracy of the DNN model was found to be the best among the flood water level prediction models. To implement the flood risk classification, we utilized extreme gradient boosting, random forest, and decision tree models. The application of these models resulted in an F1-score of 0.92 for the extreme gradient boost model, which exhibited the highest accuracy. With an increasing need for disaster (flood) management, AI-based predictive models are anticipated to reduce the damage caused by natural disasters and enhance disaster mitigation systems. Real-time collection of rainfall and water level data enables continuous learning. Furthermore, if a clear flood warning based on learned flood level patterns is issued, preemptive measures can be taken before intense flood damage occurs.

1 July 2022 in Applied Sciences
Verified
Journal Article
Open access
PDF file
DKDonghyun Kim
Donghyun Kim
HHHeechan Han
Heechan Han
WWWonjoon Wang
Wonjoon Wang
YKYujin Kang
Yujin Kang
HLHoyong Lee
Hoyong Lee
Hung Soo KimHung Soo Kim
Hung Soo Kim
Accurate pollutant prediction is essential in fields such as meteorology, meteorological disasters, and climate change studies. In this study, long short-term memory (LSTM) and deep neural network (DNN) models were applied to six pollutants and comprehensive air-quality index (CAI) predictions from 2015 to 2020 in Korea. In addition, we used the network method to find the best data sources that provide factors affecting comprehensive air-quality index behaviors. This study had two steps: (1) predicting the six pollutants, including fine dust (PM10), fine particulate matter (PM2.5), ozone (O3), sulfurous acid gas (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) using the LSTM model; (2) forecasting the CAI using the six predicted pollutants in the first step as predictors of DNNs. The predictive ability of each model for the six pollutants and CAI prediction was evaluated by comparing it with the observed air-quality data. This study showed that combining a DNN model with the network method provided a high predictive power, and this combination could be a remarkable strength in CAI prediction. As the need for disaster management increases, it is anticipated that the LSTM and DNN models with the network method have ample potential to track the dynamics of air pollution behaviors.

4 February 2022 in Water
Verified
Journal Article
Open access
PDF file
DKDonghyun Kim
Donghyun Kim
HHHeechan Han
Heechan Han
WWWonjoon Wang
Wonjoon Wang
Hung Soo KimHung Soo Kim
Hung Soo Kim
Accurate water level prediction is one of the important challenges in various fields such as hydrology, natural disasters, and water resources management studies. In this study, a deep neural network and a long short-term memory model were applied for water level predictions between 2000 and 2020 in the Phan Rang River Basin of Nihn Thuan located in Vietnam. In addition, a complex network model was utilized to improve the predictive ability of both models for water level prediction at the outlet point of the basin. The water level prediction by each model was compared with the observed water level data, and the predictive power for each model was evaluated using three statistical metrics: the correlation coefficient (CC), the Nash–Sutcliffe efficiency coefficient (NSE), and the normalized root-mean-squared error (NRMSE). Using all data from nearby stations, there may be distortions in the prediction due to unnecessary data for model learning. Therefore, the complex network method was applied to find best data sources providing factors contributing to water level behaviors. The results of this study showed that a combination of the long short-term memory model and the complex network provided the best predictive performance (CC: 0.99; NSE: 0.99; and NRMSE: 0.17) and was selected as the optimal model for water level prediction in this study. As the need for disaster management is gradually increasing, it is expected that the deep learning model with the complex network method have sufficient potential to reduce the damage from natural disasters and improve disaster response systems, such as in the outskirts of Vietnam.

14 April 2022 in Sustainability
Verified
Journal Article
Open access
PDF file
JKJongsung Kim
Jongsung Kim
MLMyungjin Lee
Myungjin Lee
HHHeechan Han
Heechan Han
DKDonghyun Kim
Donghyun Kim
YBYoung Hye Bae
Young Hye Bae
Hung Soo KimHung Soo Kim
Hung Soo Kim
Global climate models (GCMs) are used to analyze future climate change. However, the observed data of a specified region may differ significantly from the model since the GCM data are simulated on a global scale. To solve this problem, previous studies have used downscaling methods such as quantile mapping (QM) to correct bias in GCM precipitation. However, this method cannot be considered when certain variables affect the observation data. Therefore, the aim of this study is to propose a novel method that uses a convolution neural network (CNN) considering teleconnection. This new method considers how the global climate phenomena affect the precipitation data of a target area. In addition, various meteorological variables related to precipitation were used as explanatory variables for the CNN model. In this study, QM and the CNN models were applied to calibrate the spatial bias of GCM data for three precipitation stations in Korea (Incheon, Seoul, and Suwon), and the results were compared. According to the results, the QM method effectively corrected the range of precipitation, but the pattern of precipitation was the same at the three stations. Meanwhile, for the CNN model, the range and pattern of precipitation were corrected better than the QM method. The quantitative evaluation selected the optimal downscaling model, and the CNN model had the best performance (correlation coefficient (CC): 69% on average, root mean squared error (RMSE): 117 mm on average). Therefore, the new method suggested in this study is expected to have high utility in forecasting climate change. Finally, as a result of forecasting for future precipitation in 2100 via the CNN model, the average annual rainfall increased by 17% on average compared to the reference data.