• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.470-471
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• 2018

This paper presents a design method for combinational digital logic systems using time domain based multiplexing and common multi-terminal extension decision diagrams. The proposed method can reduce the 1)hardware, 2)logic levels and 3)pins. In the logic system design, we use two types of decision diagrams(DDs), that is the common binary decision diagrams and CMTEDDs. Also, we propose an algorithms to derive common multiple-terminal binary decision diagrams from CBDDs, and CMTEDDs from CMTBDDs. The CMTEDDs over CBDDs is more compactness in terms of number of non-terminal nodes, where the nodes for output selection variables are not included in the non-terminal nodes. In the logic design, each non-terminal nodes of an CBDDs and an CMTEDDs is realized by a multiplexer(MUX). In addition, we compare the proposed TDBM realization with the conventional one.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.687-688
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• 2011

This paper presents a design method for combinational digital logic systems using time domain based multiplexing(TDBM) and common multi-terminal extension decision diagrams(CMTEDD). The proposed method can reduce the 1)hardware, 2)logic levels and 3)pins. In the logic system design, we use two types of decision diagrams(DDs), that is the common binary decision diagrams(CBDDs) and CMTEDDs. Also, we propose an algorithms to derive common multiple-terminal binary decision diagrams(CMTBDD) from CBDDs, and CMTEDDs from CMTBDDs. The CMTEDDs over CBDDs is more compactness in terms of number of non-terminal nodes, where the nodes for output selection variables are not included in the non-terminal nodes. In the logic design, each non-terminal nodes of an CBDDs and an CMTEDDs is realized by a multiplexer(MUX). In addition, we compare the proposed TDBM realization with the conventional one.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1644-1651
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• 2022

This paper focuses on the power-level control of nuclear power plants (NPPs) in the presence of lumped disturbances. An adaptive second-order nonsingular terminal sliding mode control (ASONTSMC) scheme is proposed by resorting to the second-order nonsingular terminal sliding mode. The pre-existing mathematical model of the nuclear reactor system is firstly described based on point-reactor kinetics equations with six delayed neutron groups. Then, a second-order sliding mode control approach is proposed by integrating a proportional-derivative sliding mode (PDSM) manifold with a nonsingular terminal sliding mode (NTSM) manifold. An adaptive mechanism is designed to estimate the unknown upper bound of a lumped uncertain term that is composed of lumped disturbances and system states real-timely. The estimated values are then added to the controller, resulting in the control system capable of compensating the adverse effects of the lumped disturbances efficiently. Since the sign function is contained in the first time derivative of the real control law, the continuous input signal is obtained after integration so that the chattering effects of the conventional sliding mode control are suppressed. The robust stability of the overall control system is demonstrated through Lyapunov stability theory. Finally, the proposed control scheme is validated through simulations and comparisons with a proportional-integral-derivative (PID) controller, a super twisting sliding mode controller (STSMC), and a disturbance observer-based adaptive sliding mode controller (DO-ASMC).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.5
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• pp.708-717
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• 2015

This paper proposes a new reduction scheme of circulating current when two units of BESS (Battery Energy Storage System) are operated in parallel with conventional droop control. In case of using conventional droop, the terminal voltage of each BESS are not equal due to the unequal line impedance, which causes the circulating current. The operation performance of BESS is critically dependant on the circulating current because it increases system losses which causes the increasement of required system rating. This paper introduces a new reduction scheme of circulating current in which the terminal voltage difference of each BESS is compensated by adding feed-forward path of line voltage drop to the droop control. The feasibility of proposed scheme was first verified by computer simulations with PSCAD/EMTDC software. After then a hardware prototype with 5kW rating was built in the lab and many experiments were carried out. The experimental results were compared with the simulation results to confirm the feasibility of proposed scheme. Two parallel operating BESS with proposed scheme shows more accurate performance to suppress the circulating current than those with the conventional droop control.

• Health Policy and Management
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• v.15 no.2
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• pp.1-15
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• 2005

The aim of this study was to compare medical cost of hospice care and that of conventional care during the last year of life, and identify factors that influenced the cost. From January to August 2003 592 terminal cancer patients receiving care from 5 hospice care units and 2 hospice care teams in general hospitals were enrolled to case group. Two hundreds and seventy two terminal cancer patients receiving conventional care from 7 general hospitals were enrolled to hospital-based control group, and 1,636 terminal cancer patients from 122 general hospitals located in same regions with the 7 hospitals were enrolled to community-based control. We used characteristics and medical cost from data of National Health Insurance Cooperation. Total medical cost per beneficiary in cases was about 10 millions won, 14.5 millions in hospital-based controls and 11.1 millions in community-based controls. The hospice care saved $45\%$ over the last year of life compared with hospital-based controls (p<0.0001). Saving of inpatient cost account for approximately $80\%$ of saving per beneficiary. Hospice care saved $29\%$ of medical cost per hospitalization day compared with hospital­based controls and $17\%$ compared with community-based controls (p<0.0001). Multiple regression analyses showed that hospice care significantly saved the medical cost. This study suggest that hospice care save medical cost compared with hospital-based control and community-based control. Most of saving of inpatient cost account for approximately $80\%$ of saving of medical cost.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.692-698
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• 2001

The radio communications by SSB and VHF transceivers are still used very efficiently in coast stations and military base stations. The communication system by the conventional SSB and VHF transceivers between a coast station and a terminal is an one-to-one system. In this dissertation, however, the conventional one-to-one system is expanded to one-to-multiple systems. Then, frequencies can be used effectively for distress, urgency, safety traffic, and military communications. An ICS has been proposed and added, in this dissertation, to the conventional SSB and VHF communication systems, which can realize one-to- several terminal communications. The line switching system by the ICS is to be remote-controlled by ASK modulated PTT signals and audio signals. An ICS can change a connection between terminal and transceiver through a circuit switching system at any time. For this purpose, the author has researched and developed a ASK transmission system, ICS system, control algorithm, multiprocessor system, and moni-toring system. As a conclusion, the developed line switching control systems and equipments can be used effectively for maritime communication, military communication, fishery communication, etc.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.479-485
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• 2004

The interest of ACT (Automated Container Terminal) is increasing because of expansion of container's transportation quantity, appearance of large-sized and. high-speed vessel, high labor cost of container terminal and the change of technical level. Therefore, the ACT had been developed in several ports in the world, such as ECT (Europe Combined Terminals) and CTA (Container Terminal Altenwerder). They have studied detailed technique for the operation of ACT. In Korea, it also has increased not only expansion and improvement of container terminal, but also necessity of ACT. Now, many projects related to the development of ACT are working in Korea. And the technical improvement of operating system, automated equipments and information system has accomplished by the projects. The ACT consists of the basic equipment and the integrated information system for operating and controlling automated equipments. The productivity of ACT is maximized through efficient connection between them. Thus, the automated degree of container terminal is dependent on the developing time of operating system, reliability, transportation quantity of container, investment amount and technical level. In this paper, we propose important strategy in developing ACT through analyzing the property of each ACT.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.8
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• pp.482-492
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• 2002

This paper deals with overvoltage stresses in the field circuit of synchronous machine connected to HVDC terminal. A load rejection of the HVDC may cause generator in the station to become self-excited, resulting in a severe system overvoltage. This paper shows that violent field current oscillations can be produced by resonance between the machine inductance and the terminal capacitance. As most conventional excitation system do not allow reverses current, new topology of excitation system to allow reverse current is proposed. the proposed system can limit the rate of rise of terminal voltage during conditions of self excitation. Apart from these simulations, the nature(Magnitude and frequency) of the field transient state is explained mathematically. Finally, the EMTDC program is used for the simulation studies.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.39-47
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• 1994

The drain current reduction effect due to the side-gating phenomena resulted from interaction between the neighbor gates is lead to degradation of circuit performance. In this paper, these effect were modelized for circuit simulation with the shift of threshold voltage resulting from negative charge formation and the analysis of substrate leakage current resulting trapping effect. To remove dificiencies of the conventional three terminal structure, these model were implemented in SPICE with the four terminal structure, and then the constructed environment enables the simulation of circuit performance degradation resulted from side-gating effect. The validity of implemented model is proved by comparisoin with experiment data.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.16-18
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• 2006

This paper presents a sensorless speed control of Brushless DC motor using terminal voltage of one phase. Rotor position information is extracted by indirectly sensing the Back-EMF from only one of the three terminal voltages for a three phase BLDC motor. This is a advantage for the cost saving and size reduction. Also, it can be substituted for conventional Hall-IC or encoder applied to position control.