• Journal of Environmental Science International
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• v.4 no.1
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• pp.71-80
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• 1995

A discrete state space model for a multiple-reach river system is formulated using the dynamics of biochemical oxygen demand(BOD) and dissolved oxygen(DO). A hierarchical optimization technique, which is applicable to large-scale systems with time-delays in states, is also described to control stream quality in a river as an optimal manner based on the interaction prediction method. The steady state tracking error of the proposed method is determined analytically and a necessary and sufficient condition on which a constant target tracking problem has zero steady-state error is derived. Computer simulations for the river pollution model illustrate the algorithm.

• KIEE International Transactions on Power Engineering
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• v.4A no.4
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• pp.207-213
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• 2004

In this paper, the on-line volt/var control algorithms of the Load Tap Changer (LTC) transformer and Shunt Capacitor (SC) are proposed for distribution volt/var compensation. In the existing volt/var control of the distribution substation, the feeder voltage and reactive power demand of the distribution are mainly controlled by the LTC transformer tap position and on/off operation of the Sc. It is very difficult to maintain volt/var at the distribution networks within the satisfactory levels due to the discrete operation characteristics of the LTC and SC. In addition, there is the limitation of the LTC and SC operation times, which affects their functional lifetimes. The proposed volt/var control algorithm determines an optimal tap position of the LTC and on/off status of the SC at a distribution substation with multiple connected feeders. The mathematical equations of the proposed method are introduced. A simple case study is performed to verify the effectiveness of the proposed method.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.781-783
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• 1996

An important purpose of screening DSM(Demand Side Management) programs is to determine which programs or technologies seem to be moot worthy of further development, given the characteristics of the particular utility system. Complication found in screening DSM technologies is the consideration of costs and benefits from several perspectives : the utility, society, participants, free riders and nonparticipants. In this paper, a nation-wide DSM screening model is presented using a rigorous mathematical formulation on the financial basis and the concept of marginal coots considering all affected parties inside the nation is fully exploited.

• Journal of Power Electronics
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• v.7 no.2
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• pp.132-139
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• 2007

Electrical motors are an integral part of industrial plants with no less than 5 billion motors built world wide every year. The demand for low-cost brushless DC (BLDC) motors has increased in industrial applications. This paper presents a BLDC motor control algorithm for low-cost motor drive applications using general purpose microcontrollers which have only one on-chip timer. This paper describes how to realize pulse width modulation (PWM) signals with general input/output (I/O) ports to control a three-phase permanent magnet brushless DC motor using the timer interrupt on MSP430F1232.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.87.1-87
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• 2003

Powdery mildew on strawberry plants, caused by Spherotheca aphanis (Wallr.) U. Braun var. aphanis, is the most serious disease for strawberry production. There is a demand to develop the substitutes for chemicals which are more environment friendly materials. Control of powdery mildew was evaluated on Akihime, Sachinoka, Dochiodome, Noyho and Redpearl varieties grown in the greenhouse. Applications of 1％, 0.5％, and 0.25％ of sodium bicarbonate (NaHCO3Nyoho in greenhouse experiments. Non-phytotoxicity was revealed on the leaves and fruits of strawberry at these concentrations. This$.$result indicates that a mixture of sodium bicarbonate and tween 20 is a useful substitute for fungicides to control powdery mildew of strawberry.

• Annual Conference of KIPS
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• 2022.05a
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• pp.82-83
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• 2022

Ad-hoc On-demand Distance Vector (AODV), is one of well-designed routing protocols in mobile ad hoc networks. It supports the functionality of node mobility modules through multiple control messages to create and maintain paths for data transfer. Even though a number of studies have been conducted to achieve rapid discovery of paths across the network, but few have focused on impact of control messages. This paper proposes a method to adjust the transmission time of messages used in path recovery according to their individual characteristics. Simulation results show the improved performance of the proposed algorithm rather than traditional AODV routing protocol.

• Journal of Drive and Control
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• v.21 no.1
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• pp.53-58
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• 2024

With the recent development of intelligence and automation technologies for construction machinery, the demand for safety and efficiency of road-cutting operations has continued to increase. In response to this, a double-blade road cutter has been developed that can automatically cut roads. However, a double-blade road cutter has a load difference between the two blades due to the ground and wear conditions of the cutting blades. The difference in load between the two blades distorts the direction of travel of the cutter. In this study, a vision sensor-based driving guide technology was developed to correct the driving path of road cutters. In addition, we developed a load-sensing technology that detects blade loads in real-time and controls driving speed in the event of overload.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.32-40
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• 1994

A digital control system for the steam generator oater level control is developed using the optimal control technique. To describe the more realistic situation, a feedwater valve actuator of the first order lag is included in the overall control system. The optimal gains are obtained by the LQ method which imposes the constraints on the feedwater valve motion as well as on the deviation between the input demand signal and the output feedwater. Developed also is a Kalman observer on account of the flow measurement uncertainty at low power. And a digital controller on the feedback loop is designed which makes the system maintain the same stability margins for all power ranges. The simulation results show that the optimal digital system has good control characteristics despite the adverse dynamics of the steam generator at low power.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1382-1387
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• 2018

There is a high demand for energy efficiency improvement of factories that make up a large part of national electric energy. Therefore, research on smart FEMS technology for monitoring, analyzing and controlling energy consumption patterns is under way, but there is still a lack of research on detailed element technology for communication and control inside the factory. In this paper, we proposed OFDM VLC system based on MODBUS protocol for communication between gateways, sensors, and devices to implement smart FEMS in indoor factory environment. Assuming a conveyor belt load control, we validated the proposed system by simulating the inverter motor control and checking the performance.

• Journal of Power Electronics
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• v.14 no.2
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• pp.369-382
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• 2014

A growing dynamic electrical demand has created an increasing interest in utilizing nonconventional energy sources like Photovoltaic (PV), wind power, etc. In this context, this paper focuses on the design and development of a composite power controller (CPC) in the decoupled double synchronous reference frame (DDSRF) combining the advantages of direct power control (DPC) and voltage oriented control (VOC) for a PV sourced grid connected inverter. In addition, a controller with the inherent active filter configuration is tested with nonlinear and unbalanced loads at the point of common coupling in both grid connected and autonomous modes of operation. Furthermore, the loss and reactive power compensation due to a non-fundamental component is also incorporated in the design, and the developed DDSRF model subsequently allows independent active and reactive power control. The proposed developed model of the controller is also implemented using MATLAB-Simulink-ISE and a Xilinx system generator which evaluate both the simulated and experimental setups. The simulation and experimental results confirm the validity of the developed model. Further, simulation results for the DPC are also presented and compared with the proposed CPC to further bring out the salient features of the proposed work.