• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.393-396
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• 2007

Recently one level higher intelligent switching board than established one by the application of intelligent building and digital system are being constructed. Therefore facility's high efficiency, high degree satisfaction, miniaturaization, standardization through application of communication technology and monitoring and controlling by computer system utilized by web-basis power control system and electric IT are practiced. Especially network must be constructed through unified IBS server that monitors every educational institute's switching boards in real time control system. And I intend to create methods to save energy and raise electricity quality by power demand prediction and remote-controled management and operation. In this thesis I intend to suggest measures of forming unified system through researching educational institute's ways of constructing switching board and status analysis and overcoming technical difficulties in user's side and saving and maintenance expense.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.495-497
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• 2005

A new small signal stability analysis method for eigenvalue analysis is presented. This method is called RCF method and based on the computation of the state transition equations and state transition matrix over a specified time interval that corresponds to one or some cycle operations of the system. This method is applicable to any system with or without switching elements. As an applicable example of RCF method in power system, the one machine infinite bus system connected switching SVC at generator terminal is investigated and the results proved that variations of oscillation modes after switching operations can be calculated exactly.

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.290-292
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• 2015

We have reported about bipolar resistive switching effect on Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]:Graphene oxide composite films, which are sandwiched between aluminum and indium tin oxide electrodes. In this case, I-V sweep curve showed a hysteretic behavior, which varied according to the polarity of the applied voltage bias. The device exhibited excellent switching characteristics, with the ON/OFF ratio being approximately two orders in magnitude. The device had good endurance (10⁵ cycles without degradation) and long retention time (5 × 10³ s) at room temperature. The bistable switching behavior varied according to the trapping and de-trapping of charges on GO sites; the carrier transport was described using the space-charge-limited current (SCLC) model.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.442-445
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• 1997

A challenging activity in the manufacturing industry is to perform in real time the continuous monitoring of the process state, the situation assessment and identification of the problem on line and diagnosis of the cause and importance of the problem if he process does not work properly. This paper describes LAT(Ladder Analysis Tool) system for fault tree generation to improving the fault diagnosis of CNC machine tools. The system consists of 4 steps which can automatically ladder analysis from ladder diagram to two diagnosis function models. The two diagnostic models based on he ladder diagram is switching function model and step switching function model. This system tries to overcome diagnosis deficiencies present machine tool.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.366-373
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• 1998

In this paper, a new control strategy to reduce switching losses in three-phase voltage-source PWM converters is proposed according to Modified-Period-Average-Model (MPAN). The basic concept of this strategy is aimed at calculating the phase control voltages for controlling the source currents to be sinusoidal and in phase with the source voltages, and reducing the number of switching in each period. The phase control voltages of Period-Average-Model(PAM) is obtained according to analyzing the operation of PWM converter. In order to reduce the sensitivity to system parameters in PAM, MPAM is deduced. Then a square wave whose frequency is three times of utility frequency is added to the phase control voltages derived from MPAM. The control strategy reduces the switching losses since there exists about one-third blanking time for every phase in one period. The theoretical derivation and the control strategy are experimentally verified on a 2.5 kW three-phase voltage source converter.

• Journal of Biomedical Engineering Research
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• v.11 no.1
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• pp.1-4
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• 1990

An implementation scheme of the magnetic nerve stimulator using a switching mode power supply is proposed. By using a switching mode power supply rather than a conventional linear power supply for charging high voltage capacitors, the weight and size of the magnetic nerve stimulator can be considerably reduced. Maximum output voltage of the developed magnetic nerve stimulator using the switching mode power supply is 3,000 volts and switching time is about 100 msec. Experimental results or human nerve stimulations using the developed stimulator are presented.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.220-220
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• 1999

This paper describes the high efficiency inverter ballast circuit using very cheap microprocessor, which has been developed by the author. A variety of soft-switching techniques have been proposed to reduce the switching losses and EMI problems that occur with higher switching frequencies in switched inverter ballast. The inverter ballast circuit, which employs a temperature sensing circuits has been also proposed to improve starting performance of the fluorescent lamps. That is, the inverter ballast circuit, which employs a soft-starting circuit and soft-switching techniques to implement the power factor correction and to mitigate of power-loss and increase a life time of the fluorescent lamps, has become an attractive performance for ballasting the fluorescent lamps. In this paper, the operation and the control of the inverter ballast are described in detail and experimental results are presented. As the experimental results, when environment temperature is at -40℃, the inverter ballast circuit has low THD(4.8%) of the input current and large power factor(98%) of the lamp current. The proposed improved ballast circuit appears to be a good performance for ballasting fluorescent lamps.

• Archives of Pharmacal Research
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• v.17 no.6
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• pp.458-461
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• 1994

A new high-performance liquid chromatographic method with column switching has been onto a Bondapak phenyl/corsil $(37-50{\;}{\mu}m)$ precolumn and polar plasma components were washed with 0.06 M borate burffer. After valve switching, the concentrated drug were eluted in the back-flush mode and separated on a ${\mu}-Bondapak$ C18 column with acetonitrilke-phosphate buffer as the mobile phae. The method showed excellent precision, accuracy and speed with detection limit of $0.01{\;}{\mug}/ml^{-1}$. Total analysis time per smaple was less than 20 min and the coefficients of variation for intra and inter-assay were less than 5.635. This method has been successfully applied to plasma smaples from eats after oral administration of omeprazole.

• 전기의세계
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• v.29 no.10
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• pp.678-688
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• 1980

This paper is concerned with the computer design of the multiple-output switching functions by using the improved MASK method in order to obtain the paramount prime implicants (prime implicants of the multiple-output switching function) and new algorithm to design the optimal logic network. All the given minterms for each function are considered as minterms of one switching function to simplify the desigh procedures. And then the improved MASK method whose memory requirement and time consuming are much less than any existing known method is applied to identify the paramount prime implicants. In selecting the irredundant paramount prime implicants, new cost criteria are generated. This design technuque is suitable both for solving a problem by hand or programming it on a digital computer.

• KIEE International Transactions on Power Engineering
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• v.4A no.2
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• pp.79-83
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• 2004

A new small signal stability analysis method for eigenvalue analysis is presented. This method utilizes the Resistive Companion Form (RCF) for the computation of the transition matrix over a specified time interval, which corresponds to a single cycle operation of the system. This method is applicable to any system, with or without switching element. An illustrative example of the method is presented and the eigenvalues are compared with those of the conventional state space method (analog) in order to demonstrate the accuracy of the proposed eigenvalue analysis method. Also, the variations of oscillation modes that are caused by the switching operation can be precisely analyzed using this method.