• Proceedings of the KSME Conference
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• 2001.11a
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• pp.810-814
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• 2001

power transfer breaker is a device used to transfer the load from the electricity power line to the emergency generators. In case of overload, it also functions as a circuit breaker. In this work, a new mechanism for the device is suggested. Among the various design challenges, optimization of the trigger mechanism is identified as of central importance. Optimal design decisions are made with the use of Taguchi method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.10
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• pp.15-20
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• 2013

In this paper, wireless power transfer system using the magnetic resonance was designed and applied to LED lighting for implementation of wireless lighting. This lighting was made by the converted DC driving type and the direct AC driving type. In the former, transferred AC power was rectified into DC and regulated to the specified voltage value, which leads to produce the loss at the rectifying and regulating circuit. In the latter, wireless-transferred AC power was directly applied to LED, which get rid of the loss derived from the additional circuit. For the efficiency-comparison between the former and the latter, the power at each stage was measured when the same optical output radiated from LED lighting part. The result revealed that the direct AC driving type had 18% higher efficiency than the DC driving type and confirmed that LED lighting using magnetic resonance wireless power transfer system can be efficient by direct AC power supply. And the direct AC driving type had the simple circuit structure and the simple LED lighting formation, so this can leads to various application.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.48-54
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• 2017

The transfer influence coefficient method which is an vibration analysis algorithm based on the transfer of influence coefficient is applied to the free vibration analysis of double cylindrical shells. After the computational programs for the free vibration analysis of double cylindrical shells were made using the transfer influence coefficient method and the transfer matrix method, we compared the results using the transfer influence coefficient method with those by the transfer matrix method. The transfer influence coefficient method provided the good computational results in the free vibration analysis of double cylindrical shells. In particular, The results of the transfer influence coefficient method are superior to those of the transfer matrix method when the stiffness of internal springs connecting a inside cylindrical shell and a outside cylindrical shell is very large.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.279-285
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• 2019

This study proposes an enhanced switching pattern that can improve energy transfer efficiency in an active cell-balancing circuit using a multiwinding transformer. This balancing circuit performs cell balancing by transferring energy stored in a specific cell with high energy to another cell containing low energy through a multiwinding transformer. The circuit operates in flyback and buck-boost modes in accordance with the energy transfer path. In the conventional flyback mode, the leakage inductance of the transformer and the stray inductance component of winding can transfer energy to an undesired path during the balancing operation. This case results in cell imbalance during the cell-balancing process, which reduces the energy transfer efficiency. An enhanced switching pattern that can effectively perform cell balancing by minimizing the amount of energy transferred to the nontarget cells due to the leakage inductance components in the flyback mode is proposed. Energy transfer efficiency and balancing speed can be significantly improved using the proposed switching pattern compared with that using the conventional switching pattern. The performance improvements are verified by experiments using a 1 W prototype cell-balancing circuit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.45-51
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• 2012

In this paper, the wireless power transfer system using the magnetic resonance was designed and the effect of resonant coil radius and load resistance to this system was analyzed by the circuit analysis method. As a result, the calculated transmitted-power is similar to measured one, and the coil size has a small effect to the coupling coefficients in the resonant frequency band. In addition, the fact that the calculated transmitted-power according to the source frequency is similar to measured one confirms that the circuit analysis methode in this paper is valid. The input side transmission efficiency ${\eta}_i$ including only the loss in the power transfer circuit is almost 90[%] with the large coil in the 10[cm] transfer distance, and 65[%] with the small coil in 1[cm]. The source side transmission efficiency ${\eta}_s$ is 30~40[%] at both coil when load resistance below 4.7[${\Omega}$] has been connected. Considering that the maximum ${\eta}_s$ is 50[%], this is valid in the practical applications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.794-797
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• 2005

The automatic load transfer switch (ALTS), a kind of electric power switch, typically automatically transfers electrical loads from a normal electrical power source to an emergency electrical power source upon reduction or loss of normal power source voltage. It can also automatically re-transfer the load to the normal power source when the normal voltage has been restored within acceptable limits. The transfer operation of ALTS is accomplished by a spring-driven linkage mechanism. In order to control or delay the transfer switching time, the ALTS studied in this paper uses the superposed leaf springs, which are subjected to impact leadings in contacting with electrical contacts. Therefore, to confirm whether the springs has enough mechanical endurance in ALTS, we build a finite element model of the superposed lear springs using LS-DYNA and perform the impact and fatigue analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.275-281
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• 2016

A novel bidirectional magnetic wireless communication system is proposed in this study. This system provides the communication capability between the source and load sides by high-frequency signal while wireless power is transferred. Contrary to the conventional wireless communication systems using complex IC circuit and active components, the proposed system is simply composed of passive components. It is practical and beneficial for environmental robustness, cost effectiveness, and simple implementation. The detailed static analysis of the proposed system for power and communication lines is established. The proposed system is experimentally verified, and results show that a 0.1 voltage gain for communication line is obtained while a 2.0 voltage gain for the power line is achieved. The proposed system is adequate for practical applications as it allows the inductive power transfer system to wirelessly and easily communicate between the source and load sides.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.17-24
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• 2010

The power transfer capability has been recently highlighted as a key issue in many utilities with the power system more stressed and heavy loaded. The total transfer capability in the KEPCO power system is determined mainly by the voltage stability limit and many approaches for enhancement of the total transfer capability has been consistently performed. In this paper, a new transfer capability index to locate the STATCOM(Static Synchronous Compensator) effectively for enhancing the total transfer capability from a static voltage stability viewpoint is presented and it is applied to a small scale power system of IEEE 39-bus test system in order to show the effects of this index. In addition, the effect of transient stability as well as voltage stability to the total transfer capability when loads are increased is analyzed using this small scale power system.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.589-595
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• 2001

The present study conducted heat transfer analysis in multi-layer of CD-R. It is necessary to analyze heat transfer during the recording process to find optimum power and write strategy in CD-R. This study investigated effects of several parameters such as recording speed, laser power, layer thickness and thermal property. The calculated results presented temperature distribution in the multi-layer and detailed information of recording characteristics. Optimum laser power was estimated, comparing an optimum mark length with the calculated mark lengths. The results showed that the optimum laser power was influenced significantly by the layer thickness and the thermal properties of the dye.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.910-915
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• 2014

Recently, wireless power transfer (WPT) system is widely studied. WPT system is very attractive because it removes power cables from home appliances, office equipment and battery chargers for electric vehicle. However, pickup's posture affects the performance greatly. In this paper a new pickup system whose output voltage is less sensitive to its posture is proposed. The proposed pickup system is composed of three coils perpendicular to each other. A prototype is constructed and tested, and its usefulness is verified.