• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.231-232
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• 2011

It is very important thing to efficiently utilize the solar power. The conventional solar power system has no energy storage device. So the conventional system cannot cut the peak load. In this paper, the solar power system with the energy storage device and the operation algorithm of peak cut function was proposed to cut the peak load. The algorithm principle is proposed based on the insolation curve and load curve. The simulation and experiment was performed to demonstrate the validity of the peak cut algorithm.

• Transactions on Electrical and Electronic Materials
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• v.17 no.5
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• pp.257-260
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• 2016

In this paper, two configurations (T-type and Y-type) of dual band Wilkinson Power Divider based upon Hilbert curves are presented. Formerly, the concept of Hilbert Curves was implemented in only designing microstrip antennas. In power dividers, this is the very first attempt of incorporating them for size reduction. In addition to this, an effect of inculcation of high-dielectric constant layer (Hafnium-oxide, HfO₂, ε_r= 25) between a substrate and top metallization in both configurations was investigated. The proposed configurations are designed on a high resistive silicon substrate (HRS) for L and S bands with resonating frequencies of 1.575 and 3.4 GHz. Both configurations have return loss that is better than 20 dB and an insertion loss of around 6 dB; isolation better than 30 dB was achieved for both models.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.491-493
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• 2008

This paper presents results of comparing CSC HVDC with VSC HVDC on the stability in case of connecting Haenam to Jeju electrical power system, the steady-state stability in the case of Jeju electrical power system with CSC HYDC or VSC HVDC, is validated through PV curve, QV curve of Jeju electrical power system. And in the case of CSC HVDC, it is considered that synchronous condenser is connected or not. The results are compared each other. PSS/E simulation tool is used for the steady-state stability analysis.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.151-153
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• 2007

In this paper, the control method of extracting maximum power from the seaflow energy is proposed. This system consists of buck-boost converter, bridge diode. The control is performed by using the variable duty ratio control of buck-boost converter. For extracting maximum power, it is necessary to know the seaflow turbine's maximum power curve and the seaflow speed measurement. But this makes the system difficult and expensive to implement. So this paper proposes the MPPT control method where the seaflow speed and the maximum power curve of the seaflow turbine are not required. The effectiveness of algorithm is simulated based on Matlab $Simulink^{(R)}$.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.7-9
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• 2001

Many developing countries has been voltage unstable and the inter- change capability in Korea is limited by voltage instability. In analyzing voltage stability, load model has been considered as constant power, but actual loads vary as voltage changes. In order to incorporating voltage-dependent load model. we need the low-side of P-V curve that can not be obtained by general load flow algorithm. This paper proposes a modified GCF algorithm to obtain a full low-side of P-V curve and a accurate voltage assessment index considering load model. 5-bus sample system and 19-bus real power system are applied to simulate the proposed GCF. Also. the effect of reactive power compensation is illustrated in same systems.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.3
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• pp.313-321
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• 2014

A low-power low-cost polar transmitter for EDGE is designed in $0.18{\mu}m$ CMOS. A differential delta-sigma modulator (DSM) tunes a three-terminal voltage-controlled oscillator (VCO) to perform RF phase modulation, where the VCO tuning curve is digitally pre-compensated for high linearity and the carrier frequency is calibrated by a dual-mode low-power frequency-locked loop (FLL). A digital intermediate-frequency (IF) pulse-width5 modulator (PWM) drives a complementary power-switch followed by an LC filter to achieve envelope modulation with high efficiency. The proposed transmitter with 9mW power dissipation relaxes the time alignment between the phase and envelope modulations, and achieves an error vector magnitude (EVM) of 4% and phase noise of -123dBc/Hz at 400kHz offset frequency.

• Journal of Communications and Networks
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• v.12 no.1
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• pp.1-4
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• 2010

As a countermeasure to simple power attack, the unified point addition codes for the elliptic curve cryptosystem were introduced. However, some authors proposed a different kind of power attacks to the codes. This power attack uses the observation that some internal operations in the codes behave differently for addition and doubling. In this paper, we propose a new countermeasure against such an attack. The basic idea of the new countermeasure is that, if one of the input points of the codes is transformed to an equivalent point over the underlying finite field, then the code will behave in the same manner for addition and doubling. The new countermeasure is highly efficient in that it only requires 27(n-1)/3 extra ordinary integer subtractions (in average) for the whole n-bit scalar multiplication. The timing analysis of the proposed countermeasure is also presented to confirm its SPA resistance.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.370-371
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• 2018

Recently, interest in renewable energy is increasing due to energy depletion and environmental problems. Among them, solar energy is the most popular feature for its infinite, eco-friendly, easy to maintain and high utilization. In these solar power systems, solar cells have either a current-voltage characteristic curve or a power-voltage characteristic curve with non-linear properties. Therefore, the Maximum Power Point Tracking (MPPT) technique is important to control this. In this thesis, we will discuss MPPT techniques using a boost converter and demonstrate their behavior using the PSIM program. Also, the MPPT control algorithm for solar energy generation will be proposed.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1527-1536
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• 2014

This paper investigates the optimal values of turn-on and turn-off angles, and ratio of flux linkage at turn-off angle and peak phase current positions of optimal control for accomplishing maximum output power in an 8/6 Switched Reluctance Generator (8/6 SRG). Phase current waveform is analyzed to determine optimal excitation angles (optimal turn-on and turn-off angles) of the SRG for maximum output power which is applied from a nonlinear magnetization curve in terms of control variables (dc bus voltage, shaft speed, and excitation angles). The optimal excitation angles in single pulse mode of operation are proposed via the analytical model. Simulated and experimental results have verified the accuracy of the analytical model.

• Nuclear Engineering and Technology
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• v.14 no.1
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• pp.1-9
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• 1982

Some observations from the examination of actual manhour curves for the power plant design engineering obtained from Sargent & Lundy Engineers and of a few of the model curves proposed by Bechtel, are analyzed in this paper. A model curve representing typical design engineering manhour has been determined as a probability density function for the Gamma Distribution. By means of this model curve, we strategically forecast the future engineering manpower requirements to meet the Government's long range nuclear power plan. As a sensitivity analysis, the directions for the localization of nuclear power plant design engineering, are studied in terms of the performance factor for the experienced versus inexperienced engineers.