• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.577-582
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• 2016

This Study focused on the development of SMPS (Switching Mode Power Supply) to supply the constant votage and current nevertheless LED fluorescent Light generated the electric noise (with Harmonics) and Inrush current at instant time of turn-on and off. Recently, according to the Green policy in government, the LED fluorescent Lighter showed the rapidly increasing tend as indoor and outdoor Lighter. But, because of costs, LED fluorescent Light not considered and neglected the following items; power factor, efficiency, Harmonics and Inrush current. So, we are developed the SMPS about 3 key issues as follows: 1st, power factor and efficiency is 85%. 2nd, the switching noisy by harmonic is minimized. 3rd, the Inrush current at turn on and off time is reduced the minimum 0.3 A after $100{\mu}sec$ on turnon time. The proposed SMPS adjusted by LNK 409 driver (included the high frequency modulation function). Although, the developed SMPS maintained the about 85% of power factor and efficiency. but, the SMPS must be generated low heat by the variation of minute load current at switching timing. To improve the above weak point, the developed SMPS have the feedback monitoring circuit between input side and output side to maintain the power factor and efficiency. Also, we are studied the time-constant of control circuit to output the constant voltage and current nevertheless the load disturbance of LED lighting. The LED fluorescent Light of 46W is checked the above items.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.407-410
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• 2018

As the operating frequency of an electromagnetic wave increases, the maximum output and wavelength of the wave decreases, so that the size of the circuit cannot be reduced. As a result, the fabrication of a circuit with high power (of the order of or greater than kW range) and terahertz wave frequency band is limited, due to the problem of circuit size, to the order of ${\mu}m$ to mm. In order to overcome these limitations, we propose a source design technique for 0.1 THz~0.3 GW level with cylindrical shape (diameter ~2.4 cm). Modeling and computational simulations were performed to optimize the design of the high-power electromagnetic sources based on Cherenkov radiation generation technology using the principle of plasma wakefield acceleration with ponderomotive force and artificial dielectrics. An effective design guideline has been proposed to facilitate the fabrication of high-power terahertz wave vacuum devices of large diameter that are less restricted in circuit size through objective verification.

• Clean Technology
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• v.17 no.1
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• pp.69-77
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• 2011

The intrinsic $CO_2$ separation and hydrogen production system is a novel concept using oxidation and reduction reactions of oxygen carrier for both $CO_2$ capture and high purity hydrogen production. The process consists of a fuel reactor (FR), a steam reactor (SR) and an air reactor (AR). The natural gas ($CH_4$) is oxidized to $CO_2$ and steam by the oxygen carrier in FR, whereas the steam is reduced to hydrogen by oxidation of the reduced oxygen carrier in SR. The oxygen carrier is fully oxidized by air in AR. In the present study, the chemical looping moving bed reactor having 200 L/h hydrogen production capacity is designed and the hydrodynamic properties were determined. Compared with other reactors, two moving bed reactors (FR, SR) were used to obtain high conversion and selectivity of the oxygen carrier. The desirable solid circulation rates are calculated to be in the range of $20{\sim}100kg/m^2s$ from the conceptual design. The solid circulation rate can be controlled by aeration in a loop-seal. To maintain the gas velocity in the moving beds (FR, SR) at the minimum fluidization velocity is found to be suitable for the stable operation. The solid holdup in moving beds decrease with increasing gas velocity and solid circulation rate.