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Junhee Hong
Department of Energy IT, Gachon University, Seongnam 13120, Korea

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Editorial
Published: 12 May 2021 in Applied Sciences
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Nowadays, renewable energy plays an important role in nationwide power systems

ACS Style

Zong Geem; Junhee Hong; Woohyun Hwang. Special Issue on State-of-the-Art Renewable Energy in Korea. Applied Sciences 2021, 11, 4401 .

AMA Style

Zong Geem, Junhee Hong, Woohyun Hwang. Special Issue on State-of-the-Art Renewable Energy in Korea. Applied Sciences. 2021; 11 (10):4401.

Chicago/Turabian Style

Zong Geem; Junhee Hong; Woohyun Hwang. 2021. "Special Issue on State-of-the-Art Renewable Energy in Korea." Applied Sciences 11, no. 10: 4401.

Original article
Published: 30 November 2020 in Journal of Electrical Engineering & Technology
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The rapid growth of demand for electrical energy and the depletion of fossil fuels opened the door for renewable energy; with solar energy being one of the most popular sources, as it is considered pollution free, freely available and requires minimal maintenance. This paper investigates the feasibility of using machine learning (ML) based MPPT techniques, to harness maximum power on a PV system under PSC. In this study, certain contributions to the field of PV systems and ML based systems were made by introducing nine (9) ML based MPPT techniques, by presenting three (3) experiments under different weather conditions. Decision Tree (DT), Multivariate Linear Regression (MLR), Gaussian Process Regression (GPR), Weighted K-Nearest Neighbors (WK-NN), Linear Discriminant Analysis (LDA), Bagged Tree (BT), Naïve Bayes classifier (NBC), Support Vector Machine (SVM) and Recurrent Neural Network (RNN) performances are validated and proved using MATLAB SIMULINK simulation software. The experimental results demonstrated that WK-NN performs significantly better when compared with other proposed ML based algorithms.

ACS Style

Mpho Sam Nkambule; Ali N. Hasan; Ahmed Ali; Junhee Hong; Zong Woo Geem. Comprehensive Evaluation of Machine Learning MPPT Algorithms for a PV System Under Different Weather Conditions. Journal of Electrical Engineering & Technology 2020, 16, 411 -427.

AMA Style

Mpho Sam Nkambule, Ali N. Hasan, Ahmed Ali, Junhee Hong, Zong Woo Geem. Comprehensive Evaluation of Machine Learning MPPT Algorithms for a PV System Under Different Weather Conditions. Journal of Electrical Engineering & Technology. 2020; 16 (1):411-427.

Chicago/Turabian Style

Mpho Sam Nkambule; Ali N. Hasan; Ahmed Ali; Junhee Hong; Zong Woo Geem. 2020. "Comprehensive Evaluation of Machine Learning MPPT Algorithms for a PV System Under Different Weather Conditions." Journal of Electrical Engineering & Technology 16, no. 1: 411-427.

Journal article
Published: 29 September 2020 in Sustainability
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This work focuses on the design and analysis of wind flow modifier (WFM) modeling of a vertical axis wind turbine (VAWT) for low wind profile urban areas. A simulation is carried out to examine the performance of an efficient low aspect ratio C-shaped rotor and a proposed involute-type rotor. Further, the WFM model is adapted with a stack of decreased diameter tubes from wind inlet to outlet. It accelerates the wind velocity, and its effectiveness is examined on the involute turbine. Numerical analysis is performed with a realizable K-ε model to monitor the rotor blade performance in the computational fluid dynamics (CFD) ANSYS Fluent software tool. This viscous model with an optimal three-blade rotor with 0.96 m2 rotor swept area is simulated between the turbine rotational speeds ranging from 50 to 250 rpm. The parameters, such as lift–drag coefficient, lift–drag forces, torque, power coefficient, and power at various turbine speeds, are observed. It results in a maximum power coefficient of 0.071 for the drag force rotor and 0.22 for the lift force involute rotor. Moreover, the proposed WFM with an involute rotor extensively improves the maximum power coefficient to an appreciable value of 0.397 at 5 m/s wind speed, and this facilitates efficient design in the low wind profile area.

ACS Style

MohanaSundaram Anthony; Valsalal Prasad; Kannadasan Raju; Mohammed H. Alsharif; Zong Woo Geem; Junhee Hong. Design of Rotor Blades for Vertical Axis Wind Turbine with Wind Flow Modifier for Low Wind Profile Areas. Sustainability 2020, 12, 8050 .

AMA Style

MohanaSundaram Anthony, Valsalal Prasad, Kannadasan Raju, Mohammed H. Alsharif, Zong Woo Geem, Junhee Hong. Design of Rotor Blades for Vertical Axis Wind Turbine with Wind Flow Modifier for Low Wind Profile Areas. Sustainability. 2020; 12 (19):8050.

Chicago/Turabian Style

MohanaSundaram Anthony; Valsalal Prasad; Kannadasan Raju; Mohammed H. Alsharif; Zong Woo Geem; Junhee Hong. 2020. "Design of Rotor Blades for Vertical Axis Wind Turbine with Wind Flow Modifier for Low Wind Profile Areas." Sustainability 12, no. 19: 8050.

Journal article
Published: 25 June 2020 in Ain Shams Engineering Journal
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Shunt capacitor banks (SCBs) are used in distribution systems for loss reduction, voltage stability improvement for the system nodes, and system capacity release. However, the size of these capacitors and their placement locations are design factors that have been considered as single or multi-objectives to derive maximum benefits from their installation. To find the optimal location and size of the SCBs, this study proposes the application of multi-objective salp swarm algorithms, considered at ambient temperature, in radial distribution systems. Additionally, a fuzzy-based mechanism has been utilized to identify the best-fit solution of three different objective functions. The proposed method is implemented on IEEE 15-bus and 33-bus radial distribution systems, as well as on real data taken from the Saudi Electricity Company. The results indicate improved effectiveness and higher capability of the proposed method.

ACS Style

Essam A. Al-Ammar; Ghazi A. Ghazi; Wonsuk Ko; Yasin Khan; Abderrahmane Beroual; Junhee Hong; Seung-Ho Song. Comprehensive impact analysis of ambient temperature on multi-objective capacitor placements in a radial distribution system. Ain Shams Engineering Journal 2020, 12, 717 -727.

AMA Style

Essam A. Al-Ammar, Ghazi A. Ghazi, Wonsuk Ko, Yasin Khan, Abderrahmane Beroual, Junhee Hong, Seung-Ho Song. Comprehensive impact analysis of ambient temperature on multi-objective capacitor placements in a radial distribution system. Ain Shams Engineering Journal. 2020; 12 (1):717-727.

Chicago/Turabian Style

Essam A. Al-Ammar; Ghazi A. Ghazi; Wonsuk Ko; Yasin Khan; Abderrahmane Beroual; Junhee Hong; Seung-Ho Song. 2020. "Comprehensive impact analysis of ambient temperature on multi-objective capacitor placements in a radial distribution system." Ain Shams Engineering Journal 12, no. 1: 717-727.

Review
Published: 18 June 2020 in Symmetry
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Power-consuming entities such as high performance computing (HPC) sites and large data centers are growing with the advance in information technology. In business, HPC is used to enhance the product delivery time, reduce the production cost, and decrease the time it takes to develop a new product. Today’s high level of computing power from supercomputers comes at the expense of consuming large amounts of electric power. It is necessary to consider reducing the energy required by the computing systems and the resources needed to operate these computing systems to minimize the energy utilized by HPC entities. The database could improve system energy efficiency by sampling all the components’ power consumption at regular intervals and the information contained in a database. The information stored in the database will serve as input data for energy-efficiency optimization. More so, device workload information and different usage metrics are stored in the database. There has been strong momentum in the area of artificial intelligence (AI) as a tool for optimizing and processing automation by leveraging on already existing information. This paper discusses ideas for improving energy efficiency for HPC using AI.

ACS Style

Anabi Hilary Kelechi; Mohammed H. Alsharif; Okpe Jonah Bameyi; Paul Joan Ezra; Iorshase Kator Joseph; Aaron-Anthony Atayero; Zong Woo Geem; Junhee Hong. Artificial Intelligence: An Energy Efficiency Tool for Enhanced High performance computing. Symmetry 2020, 12, 1029 .

AMA Style

Anabi Hilary Kelechi, Mohammed H. Alsharif, Okpe Jonah Bameyi, Paul Joan Ezra, Iorshase Kator Joseph, Aaron-Anthony Atayero, Zong Woo Geem, Junhee Hong. Artificial Intelligence: An Energy Efficiency Tool for Enhanced High performance computing. Symmetry. 2020; 12 (6):1029.

Chicago/Turabian Style

Anabi Hilary Kelechi; Mohammed H. Alsharif; Okpe Jonah Bameyi; Paul Joan Ezra; Iorshase Kator Joseph; Aaron-Anthony Atayero; Zong Woo Geem; Junhee Hong. 2020. "Artificial Intelligence: An Energy Efficiency Tool for Enhanced High performance computing." Symmetry 12, no. 6: 1029.

Journal article
Published: 13 May 2020 in Energies
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This paper introduces a new protection system for solar photovoltaic generator (SPVG)-connected networks. The system is a combination of voltage-restrained overcurrent relays (VROCRs) and directional overcurrent relays (DOCRs). The DOCRs are implemented to sense high fault current on the grid side, and VROCRs are deployed to sense low fault current supplied by the SPVG. Furthermore, a novel challenge for the optimal coordination of DOCRs-DOCRs and DOCRs-VROCRs is formulated. Due to the inclusion of additional constraints of VROCR, the relay coordination problem becomes more complicated. To solve this complex problem, a hybrid Harmony Search Algorithm-Bollinger Bands (HSA-BB) method is proposed. Also, the lower and upper bands in BB are dynamically adjusted with the generation number to assist the HSA in the exploration and exploitation stages. The proposed method is implemented on three different SPVG-connected networks. To exhibit the effectiveness of the proposed method, the obtained results are compared with the genetic algorithm (GA), particle swarm optimization (PSO), cuckoo search algorithm (CSA), HSA and hybrid GA-nonlinear programming (GA-NLP) method. Also, the superiority of the proposed method is evaluated using descriptive and nonparametric statistical tests.

ACS Style

Vipul N. Rajput; Kartik S. Pandya; Junhee Hong; Zong Woo Geem. A Novel Protection Scheme for Solar Photovoltaic Generator Connected Networks Using Hybrid Harmony Search Algorithm-Bollinger Bands Approach. Energies 2020, 13, 2439 .

AMA Style

Vipul N. Rajput, Kartik S. Pandya, Junhee Hong, Zong Woo Geem. A Novel Protection Scheme for Solar Photovoltaic Generator Connected Networks Using Hybrid Harmony Search Algorithm-Bollinger Bands Approach. Energies. 2020; 13 (10):2439.

Chicago/Turabian Style

Vipul N. Rajput; Kartik S. Pandya; Junhee Hong; Zong Woo Geem. 2020. "A Novel Protection Scheme for Solar Photovoltaic Generator Connected Networks Using Hybrid Harmony Search Algorithm-Bollinger Bands Approach." Energies 13, no. 10: 2439.

Journal article
Published: 13 March 2019 in Energy and Buildings
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A novel power management for nanogrids is presented. In this paper, effect of resident location in residence is taken into account for evaluation of power consumption in nanogrids. Depending on the resident location, operating conditions of heater, ventilation fan, and air-conditioner are adjusted. Electric appliances that allow delayed use, i.e., shiftable, are scheduled for efficient power management. Considering massive deployment of energy storage system (ESS) as a supplementary power source, effect of the ESS on power management is investigated. Demand response program for reduced electricity cost is also considered for power management. As a result, an objective consisting of power consumed by non-shiftable and shiftable electric appliances, power supplied/consumed by the ESS during discharging/charging, and time-varying electricity cost is formulated. Another objective for power management is a function of delays in scheduling of shiftable electric appliances. Variation of resident location combined with temporal use of electric appliances according to the resident location are considered as the resident behavior and incorporated into these two objectives. Using these two objectives, a multi-objective optimization is performed for nanogrids at each time interval. It is demonstrated by simulations that leveraging resident behavior is beneficial for power management of nanogrids. In addition, effects of the number of residents in each apartment and combined activity of each resident on the power management are presented with related simulation results.

ACS Style

Sangkeum Lee; Junho Lee; HeeDae Jung; Jintae Cho; Junhee Hong; Sangmin Lee; Dongsoo Har. Optimal power management for nanogrids based on technical information of electric appliances. Energy and Buildings 2019, 191, 174 -186.

AMA Style

Sangkeum Lee, Junho Lee, HeeDae Jung, Jintae Cho, Junhee Hong, Sangmin Lee, Dongsoo Har. Optimal power management for nanogrids based on technical information of electric appliances. Energy and Buildings. 2019; 191 ():174-186.

Chicago/Turabian Style

Sangkeum Lee; Junho Lee; HeeDae Jung; Jintae Cho; Junhee Hong; Sangmin Lee; Dongsoo Har. 2019. "Optimal power management for nanogrids based on technical information of electric appliances." Energy and Buildings 191, no. : 174-186.

Journal article
Published: 14 November 2017 in Energies
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This paper proposes a short-term frequency-response scheme of a doubly-fed induction generator (DFIG)-based wind turbine generator (WTG) for improving rotor speed recovery and frequency nadir. In the energy-releasing period, to improve the frequency nadir and rotor speed convergence by releasing a large amount of kinetic energy stored in the rotating masses in a DFIG-based WTG, the power reference is increased up to the torque limit referred to the power and reduces along with it for a predefined period which is determined based on the occurrence time of the frequency nadir in a power grid. Then, the reference decreases so that the rotor speed is forced to be converged to the preset value in the stable operating region of the rotor speed. In the energy-absorbing period, to quickly recover the rotor speed, the reference smoothly decreases with the rotor speed and time during a predefined period until it intersects with the maximum power point tracking curve. The simulation results demonstrate that the proposed scheme successfully achieves rapid frequency stabilization with the improved frequency nadir under various wind conditions based on the IEEE 14-bus system.

ACS Style

Dejian Yang; Moses Kang; Eduard Muljadi; Wenzhong Gao; Junhee Hong; Jaeseok Choi; Yong Cheol Kang. Short-Term Frequency Response of a DFIG-Based Wind Turbine Generator for Rapid Frequency Stabilization. Energies 2017, 10, 1863 .

AMA Style

Dejian Yang, Moses Kang, Eduard Muljadi, Wenzhong Gao, Junhee Hong, Jaeseok Choi, Yong Cheol Kang. Short-Term Frequency Response of a DFIG-Based Wind Turbine Generator for Rapid Frequency Stabilization. Energies. 2017; 10 (11):1863.

Chicago/Turabian Style

Dejian Yang; Moses Kang; Eduard Muljadi; Wenzhong Gao; Junhee Hong; Jaeseok Choi; Yong Cheol Kang. 2017. "Short-Term Frequency Response of a DFIG-Based Wind Turbine Generator for Rapid Frequency Stabilization." Energies 10, no. 11: 1863.