• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.755-760
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• 2003

A novel current-fed energy-recovery sustaining driver (CFERSD) for a PDP is proposed in this paper. Its main idea is to recover the energy stored in the PDP or to inject the input source energy to the PDP by using the current source built-up in the energy recovery inductor. This method provides zero-voltage-switching (ZVS) of all main power switches, the reduction of EMI, and more improved operational voltage margins with the aid of the discharge current compensation. In addition, since the current flowing through the energy recovery inductor can compensate the plasma discharge current flowing through the conducting power switches, the current stress through all main power switches can be considerably reduced. Furthermore, it features a low conduction loss and fast transient time. Operations, features and design considerations are presented and verified experimentally on a 1020X106mm sized PDP, 50kHz-switching frequency, and sustaining voltage 140V based prototype.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.85-89
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• 2003

Many single-stage PFC(power-facto.-correction) ACHC converters suffer from the high link voltage at high input voltage and light load condition. In this paper, to suppress the link voltage, a novel high power factor high efficiency PFC AC/DC converter is proposed using the single controller which generates two gate signals so that one of them is used far gate signal of the flyback DC/DC converter switch and the other is applied to the Boost PFC stage. A 130w prototype for LCD monitor adapter with universal input $(90-265V_{rms})$ and 19.5V 6.7A output is implemented to verify the operational principles and performances. The experimental results show that the maximum link voltage stress is about 450V at 270Vac input voltage. Moreover, efficiency and power factor are over $84\%$ and 0.95, respectively, under the full load condition.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.2
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• pp.170-175
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• 2000

A new quasi-parallel resonant DC link inverter is proposed for three phase soft switching application. By i inserting only one additional switch, the proposed inverter excludes both voltage stresses and restricted PWM p problems, which are demerits of the conventional resonant inverter. In this paper, the circuit operations are e explained in detail using the operational mode analysis of the proposed inverter and design methods of the r resonant components are suggest('x:l. Lastly, the applicable possibility of the proposed inverter is vel예fied t through the experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.485-485
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• 2014

배관 가동시 여러 지점에서 가속도를 측정, 이를 이용하여 배관의 어느 부위에 stress가 많이 걸리는지 해석적으로 확인하기 위한 연구이다. 먼저, 배관 설계시 사용된 CEASER II의 정보를 기반으로 해석 모델을 만들었다. 해석 모델을 바탕으로 측정 포인트를 산정한 후, 가동 중인 배관의 가속도를 측정하였다. 측정된 가속도 data를 OMA(Operational Modal Analysis) method를 이용하여 Mode shape 및 Frequency를 추출한 후 이를 바탕으로 배관의 FE 모델을 Updating 하였다. Updating 된 배관 FE 모델에 측정된 가속도 data가 나오도록 Force를 가해 배관에 걸리는 stress를 계산하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.3
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• pp.31-39
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• 2012

This paper presents a high efficiency coupled inductor boost DC-DC converter that uses a simple clamp circuit and the coupled inductor and thus overcomes output voltage limit of the conventional boost converter. The proposed converter solves problems of voltage stress of the power semiconductor switch and reverse recovery of the output diode using a simple clamp circuit composed of a diode and a capacitor, and thus the converter improves its total efficiency. In this paper, the operational principle of the proposed converter is explained by each mode and then a design example for the prototype converter based on the explanation is shown. And good performance of the proposed converter is verified through experimental results of the prototype converter that is implemented with the designed circuit parameters.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.245-251
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• 1999

The structural analysis of a reactor coolant pump(RCP) of a nuclear power plant is very important for the safety assessment of the plant. Accurate boundary conditions for the heat transfer coefficient are required for reliable thermal stress analysis of the pump casing, especially in transient operations of the pump since the coolant properties are largely dependent on operational conditions. In the present study, a 3D mixed flow type coolant pump was modeled from the RCP drawings and analyzed in the steady state and number of transient flow conditions by using a commercial code STAR-CD. From the result of the computation, it is seem that the average heat transfer coefficients for the cases considered are found to be the suggested values of the manufacturer, Westinghouse Energy System. The unevenness in local heat transfer coefficients, however, is found to be considerable so that the use of average heat transfer coefficients in all boundaries might not give reliable thermal stresses.

• Steel and Composite Structures
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• v.22 no.6
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• pp.1391-1415
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• 2016

Limit load of pressure bearing structures was reviewed in this article. By means of the finite element analysis, limit load of pressurized cylinder with nozzle was taken as an example. Stress classification method and Elastic-plastic finite element analysis combining with limit load determination methods were used to determine limit load of cylinder with nozzle. Comparison of limit load determined by different methods, the results indicated that limit load determined by linearization method was the smallest. Limit load determined by twice elastic slope criterion was the nearest than experimental results. Elastic-plastic finite element analysis had comparably computational precision, but required time consuming. And then the requirements of computer processing and storage capacity by power system became higher and higher. Most of criteria for limit load estimation included any human factors based on a certain substantive characteristics of experimental results. The reasonable criterion should be objective and operational.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.5-6
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• 2010

RCD clamp is used for a low cost flyback converter to clamp the voltage spikes caused by the leakage inductance of the flyback transformer. In this paper, the operational characteristics of the flyback converter with the clamp circuit are analyzed using an equivalent circuit. The simulation and experimental results are provided to verify the proposed analysis.

• Journal of Pharmacopuncture
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• v.26 no.1
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• pp.77-85
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• 2023

Objectives: The coronavirus disease 2019 has deteriorated mental health, particularly in mothers with elementary school children. Although the country has developed several health promotion programs to preserve mental health, no program has incorporated Korean medicine. Thus, this study focuses on developing vital Korean medicine mental health care programs. Methods: The program follows the Korean medicine health promotion program principles. Guidelines, reports, research, and previous programs were analyzed to form interventions and lecture content. Results: Pellets, hot packs, meditation, lavender oil, and green tea were selected as final intervention strategies. Mental health-related guidelines were analyzed to produce stress management lecture materials. In addition, an operational methods and evaluation tool manual was created. Conclusion: We designed a health promotion program capitalizing on Korean medicine to improve mental health. This program will be assessed and accordingly improved through practical applications.

• Journal of applied mathematics & informatics
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• v.41 no.5
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• pp.973-988
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• 2023

In real-life scenarios, we may have to deal with real numbers or numbers in intervals or a combination of both to solve multi-criteria decision-making (MCDM) problems. Also, we may come across a situation where we must combine this interval and actual number membership values into a single real number. The most significant factor in combining these membership values into a single value is by using aggregation operators or scoring algorithms. To overcome such a situation, we suggest the cubic hypersoft set (CHSS) concept as a workaround. Ultimately, this makes it simple for the decision-maker to obtain information without misconceptions. The primary aim of this study is to establish some operational laws for the cubic hypersoft set, present the fundamental properties of aggregation operators and propose an algorithm by using the technique of order of preference by similarity to the ideal solution (TOPSIS) technique based on correlation coefficients to analyze the stress-coping skills of workers.