• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.22-29
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• 2002

Usually, much harmonics are included and cause harmonic loss of motor, torque pulsation, electro-magnetic noise and shock etc. by switching function of inverter when drive induction motor variableness inside. It applied partial resonant Buck converter and three phase voltage type SPWM inverter circuit to induction motor driving system in this paper that see to solve such problem. Changed operation condition variously to do input current of circuit that propose sine-wave by unit power factor almost and capacitor supplied bringing back to life voltage by power supply arranging properly assistance diode and electric power switching. Power factor and efficiency improved as that minimize variation of input at power supply voltage polarity reverse by that add voltage reversal function. Also, by using output filter, reduced harmonic of output line to line voltage components, and introduce state space analysis and forecast operation of rectifier. Such all items confirmed validity through simulation and an experiment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.588-597
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• 2016

In this study, we attempted to improve the biogas production efficiency by varying the mixing ratio of the mixed sludge of organic wastes in the improved single-phase anaerobic digestion process. The types of organic waste used in this study were raw sewage sludge, food wastewater leachate and livestock excretions. The biomethane potential was determined through the BMP test. The results showed that the biomethane potential of the livestock excretions was the highest at $1.55m^3CN4/kgVS$, and that the highest value of the composite sample, containing primary sludge, food waste leachate and livestock excretions at proportions of 50%, 30% and 20% respectively) was $0.43m^3CN4/kgVS$. On the other hand, the optimal mixture ratio of composite sludge in the demonstration plant was 68.5 (raw sludge) : 18.0 (food waste leachate) : 13.5 (livestock excretions), which was a somewhat different result from that obtained in the BMP test. This difference was attributed to the changes in the composite sludge properties and digester operating conditions, such as the retention time. The amount of biogas produced in the single-phase anaerobic digestion process was $2,514m^3/d$ with a methane content of 62.8%. Considering the value of $2,319m^3/d$ of biogas produced as its design capacity, it was considered that this process demonstrated the maximum capacity. Also, through this study, it was shown that, in the case of the anaerobic digestion process, the two-phase digestion process is better in terms of its stable tank operation and high efficiency, whereas the existing single-phase digestion process allows for the improvement of the digestion efficiency and performance.

• The Korean Journal of Physiology and Pharmacology
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• v.12 no.5
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• pp.267-274
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• 2008

Since first discovered in chick skeletal muscles, stretch-activated channels (SACs) have been proposed as a probable mechano-transducer of the mechanical stimulus at the cellular level. Channel properties have been studied in both the single-channel and the whole-cell level. There is growing evidence to indicate that major stretch-induced changes in electrical activity are mediated by activation of these channels. We aimed to investigate the mechanism of stretch-induced automaticity by exploiting a recent mathematical model of rat atrial myocytes which had been established to reproduce cellular activities such as the action potential, $Ca^{2+}$ transients, and contractile force. The incorporation of SACs into the mathematical model, based on experimental results, successfully reproduced the repetitive firing of spontaneous action potentials by stretch. The induced automaticity was composed of two phases. The early phase was driven by increased background conductance of voltage-gated $Na^+$ channel, whereas the later phase was driven by the reverse-mode operation of $Na^+/Ca^{2+}$ exchange current secondary to the accumulation of $Na^+$ and $Ca^{2+}$ through SACs. These results of simulation successfully demonstrate how the SACs can induce automaticity in a single atrial myocyte which may act as a focus to initiate and maintain atrial fibrillation in concert with other arrhythmogenic changes in the heart.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.4
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• pp.121-127
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• 2024

In this paper, FEM (Front-End Module) MMIC, a key component for the application of the satellite communication terminal transmission and reception module of the multi-phase array structure, was designed and verified as a single chip by designing the Power Amplifier (PA) and the Low Noise Amplifier (LNA). It was manufactured using the GaAs PP10 (100nm) process, a compound semiconductor process from Win-semiconductors, and the operating frequency band of 7.2-10.5GHz operation, output 1W, and noise index of 1.5dB or less were secured using a dedicated test board. The developed FEM MMIC can be used as a single chip, and the components PA and LNA can also be used as each device. The developed device will be used in various applications of Minsu/Gunsu using the X band and the localization of overseas parts.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.5
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• pp.1079-1087
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• 2018

Binary scalar multiplication which is the main operation of elliptic curve cryptography is vulnerable to the side-channel analysis. Especially, it is vulnerable to the side-channel analysis which uses power consumption and electromagnetic emission patterns. Thus, various countermeasures have been studied. However, they have focused on eliminating patterns of data dependent branches, statistical characteristic according to intermediate values, or the interrelationships between data. No countermeasure have been taken into account for the secure design of the key bit check phase, although the secret scalar bits are directly loaded during that phase. Therefore, in this paper, we demonstrate that we can extract secret scalar bits with 100% success rate using a single power or a single electromagnetic trace by performing key bit-dependent attack on hardware implementation of binary scalar multiplication algorithm. Experiments are focused on the $Montgomery-L{\acute{o}}pez-Dahab$ ladder algorithm protected by scalar randomization. Our attack does not require sophisticated pre-processing and can defeat existing countermeasures using a single-trace. As a result, we propose a countermeasure and suggest that it should be applied.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.7-12
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• 2011

This paper proposes a differential Colpitts-VCO circuit suitable for low phase noise oscillation at the sub-1V supply voltage. Oscillation with low phase noise at the sub-1V supply voltage is facilitated by employing inductors as the current sources of the proposed circuit. One of the two feedback capacitors of the single-ended Colpitts oscillator in the proposed circuit is replaced with the MOS varactor in order to further reduce the resonator loss. Post-layout simulation results using a $0.18{\mu}m$ RF CMOS technology show that the phase noises at the 1MHz offset frequency of the proposed circuit oscillating at the sub-1V supply voltages of 0.6 to 0.9 V are at least 7 dBc/Hz lower than those of the well-known cross-coupled differential VCO.

• Journal of information and communication convergence engineering
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• v.4 no.4
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• pp.170-173
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• 2006

Recently, with increasing efficiency of DSC (photo-electrochemical using a nano-particle), The Performance of DSC solar generation system also needs improvement. The approach consists of a Fly-back DC-DC (transfer ratio 1:10) converter to boost the DSC cell voltage to 300VDC. The four switch (MOSFET) inverter is employed to produce 220V, 60Hz AC outputs. High performance, easy manufacturability, lower component count., safety and cost are addressed. Protection and diagnostic features form an important part of the design. Another highlight of the proposed design is the control strategy, which allows the inverter to adapt to the: requirements of the load as well as the power source. A unique aspect of the design is the use of the DSP TMS320LF2406 to control the inverter by current and voltage feed-back. Efficient and smooth control of the: power drawn from the DSC Cell is achieved by controlling the front end DC-DC converter in current mode.

• Journal of Power Electronics
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• v.5 no.1
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• pp.55-61
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• 2005

A fuel cell (FC) system includes a fuel processor plus subsystems to manage air, water, and thermal energy, and electric power. The overall system is high-priced and needs peripheral devices. In this paper, a FC simulator is designed and constructed with the electrical characteristics of a fuel cell generation (FCG) system, using uses a simple buck converter to overcome these disadvantages. The characteristic voltage and current (V-I) curve for the FC simulator is controlled by a simplified linear function. In addition, to verify FCG system performance and operation, a full-bridge DC/DC converter and a single-phase DC/AC inverter were designed and constructed for FC applications. Close agreement between the simulation and experimental results confirms the validity and usefulness of the proposed FC simulator.

• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.538-545
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• 2012

In this paper a novel cascaded transformer multilevel inverter is proposed. Each basic unit of the inverter includes two DC sources, single phase transformers and semiconductor switches. This inverter, which operates as symmetric and asymmetric, can output more number of voltage levels in the same number of the switching devices. Besides, the number of gate driving circuits is reduced, which leads to circuit size reduction and lower power consumption in the driving circuits. Moreover, several methods to determination of transformers turn ratio in proposed inverter are presented. Theoretical analysis, simulation results using MATLAB/SIMULINK and experimental results are provided to verify the operation of the suggested inverter.

• Journal of Power Electronics
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• v.15 no.3
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• pp.644-651
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• 2015

This paper introduces a novel digital one cycle control (DOCC) boost power factor correction (PFC) converter. The proposed PFC converter realizes the FPGA-based DOCC control approach for single-phase PFC rectifiers without input voltage sensing or a complicated two-loop compensation design. It can also achieve a high power factor and the operation of low harmonic input current ingredients over universal loads in continuous conduction mode. The trailing triangle modulation adopted in this approach makes the acquisition of the average input current an easy process. The controller implementation is based on a boost topology power circuit with low speed, low-resolution A/D converters, and economical FPGA development board. Experimental results demonstrate that the proposed PFC rectifier can obtain a PF value of up to 0.999 and a minimum THD of at least 1.9% using a 120W prototype.