• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.140-143
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• 1988

In this study, so called high frequency cycloconverter which converts commercial so power source directly to high frequency power source is proposed. In this system, the circulating current play very important role. Its state and magnitude effects on system characteristics. This paper deals with the control method of the circulating current and side band component analysis of high frequency side current which is produced by it.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.843-846
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• 2008

There are a lot of municipalities that do not grasp even by the current state of having public facilities though various management&maintenance researches have been done. Therefore this research aimed to make it to the foundation of the maintenance management plan establishment of the municipality in the future through investigating, analyzing the current state of management&maintenance of the public facilities. Tn the beginning, I collected data through a questionnaire of the community facilities of the municipality. To read the current state of the management condition of the object facilities from the collection data, I applied the radar chart that used the deviation value of the evaluation index and PPM matrix. As a result of the analysis, I discovered that there is a municipality thought to having efficient facilities maintenance management.

• Korean journal of food and cookery science
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• v.32 no.4
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• pp.503-516
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• 2016

Purpose: The purpose of this study was to examine the current state of usage and education participation intention for Yaksun food according to demographic characteristics. Methods: The questionnaire for the survey was distributed to 300 students, who were enrolled in culinary education program at Seoul Institute of Technology and Education from September 5, 2014 to September 20, 2014, and 264 responses were used for analysis. Results: Awareness regarding Yaksun food was low, but the intention to participate in the Yaksun food class was high. The information searching route for Yaksun food was mainly television, radio or internet. Memil-jeonbyeong ssam was the most eaten menu item and Nokdu-Samgye tang was the most popular menu item. Among the different types of Yaksun food, vegetable dishes, steamed dishes, rice dishes and roasted dishes were preferred in this order. The most preferred educational institution for Yaksun food was the cultural center, and the most preferred educational period for Yaksun food was less than three months. The most important point in the Yaksun food class was practical application in real life. Also, the current state of usage for Yaksun food and the intent to participate in an education program for Yaksun food was statistically different according to demographic characteristics. With respect to the current state of usage for Yaksun food, the information searching route for Yaksun food was statistically different according to occupation, cooking career and lives and Yaksun cuisine type preference according to gender, occupation, income and households. Also, with respect to education program participation intention for Yaksun food, educational institution preference for Yaksun food was statistically different according to gender, age, occupation, cooking career, income and lives. Conclusion: Based on these results, this research concludes that for developing an educational program for Yaksun food, it is important to analyze the target customers' demographic characteristics and their needs. Furthermore, it shows that there is a need to develop various educational programs and menus for Yaksun food.

• The monthly packaging world
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• s.318
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• pp.71-76
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• 2019

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.10-14
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• 2008

Differently from BSCCO tapes which are fabricated by powder-in-tube method, the coated conductors are made by the evaporation of YBCO on metal substrate. Due to this structural merit, although the coated conductors are generally used for large current transportation, they are expected to be favorable to the purpose of the fault current limitation as well. In this study, using YBCO coated conductor having copper stabilizer formed by plating technique(produced by Superpower Co.), we investigated the over-current characteristics of the coated conductor. The coated conductors had 85 A $I_c$ and 90 K $T_c$. The resistance of the conductor was 0.93 $m{\Omega}/cm$ at 300 K and 0.17 $m{\Omega}/cm$ at the temperature right above $T_c$. To the coated conductors, we applied the voltages of the range from 150 $V_{rms}$ to 230 $V_{rms}$ and measured the V-I curves using four probe method. From the results, we could analyze the electric behavior of the coated conductor in flux flow state. As the current exceed $I_c$, the currents were distributed into the superconductor and metal stabilizer. The amounts of the currents shared through both current paths were calculated under the assumption that the ,Joule heating was perfectly eliminated by $LN_2$ surrounding the conductor. Finally, the condition for the stable current flowing state which does not affect the conductor was established from the analysis on the over-current characteristics.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.530-533
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• 1987

In high-frequency switched mode converters, Series Resonant Converter (SRC) is investigated using state-plane method. Phase plane trajectories of the SRC permit a direct closed form solution of the steady state operation and can make problems easy to solve. This paper describes steady state responses and characteristics of the SRC with respect to various circuit factors. The magnitute of steady state response and the average current through load are clearly related to how such the switching frequency differs from the resonant frequency. The results of the steady state analysis can be used to estimate the device and component stress on the power circuit.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.405-415
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• 2016

This paper presents a model predictive control for shunt active power filters in synchronous reference frame using space vector pulse-width modulation (SVPWM). The three phase load currents are transformed into synchronous rotating reference frame in order to reduce the order of the control system. The proposed current controller calculates reference current command for harmonic current components in synchronous frame. The fundamental load current components are transformed into dc components revealing only the harmonics. The predictive current controller will add robustness and fast compensation to generate commands to the SVPWM which minimizes switching frequency while maintaining fast harmonic compensation. By using the model predictive control, the optimal switching state to be applied to the next sampling time is selected. The filter current contains only the harmonic components, which are the reference compensating currents. In this method the supply current will be equal to the fundamental component of load current and a part of the current at fundamental frequency for losses of the inverter. Mathematical analysis and the feasibility of the suggested approach are verified through simulation results under steady state and transient conditions for non-linear load. The effectiveness of the proposed controller is confirmed through experimental validation.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.30-36
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• 2009

This paper aims at the precursor analysis and DB development of electrical fires based on thermal and current signals for partial disconnection and poor contact on electric wires through experiments and simulations. Also, DB system required for developing the precursor DB with these data was studied and designed. Firstly, in case of partial disconnection, characteristics were derived and analyzed by experiment and electrical-thermal finite element method(Flux 3D) on the model wires which consist of VCTF and IV electric wires. Based on the characteristics, About 351 partial disconnection precursor patterns were generated by the thermal analysis for electric wire according to deterioration time under normal state and 200% overload state of rated current. Secondly, in order to develop poor contact precursor patterns, temperature value and the current signal were considered. In simulating the poor contact situation on connector area of MCCB, connection torque was changed. Through the experimental analysis, about 251 poor contact precursor patterns were generated. Finally, Using thermal precursor patterns obtained by partial disconnection and poor contact, electrical fire thermal precursor DB was developed.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.313-316
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• 1989

A steady state analysis of a load commutated current source inverter which is widely used in high voltage - high power induction motor drive systems at present is presented and its related results are discussed. This analysis proposes a method by which we can determine the output capacitor playing a dominant role on the performance of the system. It is shown that the capacitance of output capacitors is mainly dependent on the range of frequencies that the inverter is operated in the load commutated state.

• Asian Journal of Business Environment
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• v.9 no.4
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• pp.29-34
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• 2019

Purpose - The purpose of the research is to assess the current state of cryptocurrency in Vietnam and to provide several solutions and recommendations to the Government, the State Bank of Vietnam (SBV) and other relevant agencies for monitoring, managing, and controlling cryptocurrency effectively and efficiently. Research design, data and methodology - The study is based on the assessment and analysis of cryptocurrency in the world and the real situation of cryptocurrency in Vietnam in order to provide solutions to the controllable development of operation of this currency. Results - The study indicates the current operations of cryptocurrency in Vietnam and provides several suggestions to effectively control this currency. Conclusion - According to the study on current cryptocurrency and the situation of cryptocurrency in Vietnam, the author has proposed a number of solutions to provide suggestions to manage and develop the operations of cryptocurrency in a most practical manner. The governments of many countries in the world, including the Government of Vietnam, need more time as well as appropriate technology improvements to take advantage of these new digital currencies; therefore, they still need to ensure safety in compliance with the control and regulatory capabilities of the central government and central banks.