• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.68-75
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• 2012

Small hydropower is one of the many types of new and renewable energy, which is planning to develop, as the country is abundant in endowed resources. In order to fully utilize small hydropower resources, there is a need for greater precision in quantifying small hydropower resources and establish an environment in which energy sources can be discovered using the small hydropower resource management system. This study has given greater precision to calculate annual electricity generation and capacity of small hydropower plants of Nakdong river system by inquiring into average annual rainfall, basin area and runoff coefficient, which is anticipated to promote small hydropower resources utilization. Small hydropower resource management system was also established by additionally providing base information on quantified small hydropower resources and analysis function and small hydropower generator status, rivers, basin, rainfall gauging station, water level gauging station etc.. Small hydropower resource management system can be used gather basic information for positive applications of small hydropower energy nationwide.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.109-109
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• 2009

This paper represented driving characteristic of a thin-type ultrasonic motor by fabricating and utilizing two kinds of drivers which could generate sinusoidal wave, square wave, respectively. A thin brass plate was used as a cross shaped vibrator and sixteen ceramic plates were attached on upper and bottom side of the brass plate. From the thin stator, elliptical displacements of the four contact tips were obtained. Speed, torque, and current were measured by applying sinusoidal waves through driving equipment such as function generator, power amplifier: to measure characteristic of the motor. As a result, the speed and the torque changed linearly at either driving frequency of 88.6 ~ 87.6[kHz] or voltage of 24~36[V]. Two-drivers which generate sinusoidal waves and square waves were designed respectively, and then were compared through some experiments in order to be put to practical use. In conclusion, the drivers had similar characteristic of speed-torque at similar frequency and voltage. It was able to control the motor linearly by using the driver generating square wave among two-drivers. Besides, it also was possible to make the drivers smaller.

• ETRI Journal
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• v.35 no.3
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• pp.448-458
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• 2013

This paper presents a generalized post-processing technique for enhancing the pseudorandomness of digital chaotic oscillators through a nonlinear XOR-based operation with rotation and feedback. The technique allows full utilization of the chaotic output as pseudorandom number generators and improves throughput without a significant area penalty. Digital design of a third-order chaotic system with maximum function nonlinearity is presented with verified chaotic dynamics. The proposed post-processing technique eliminates statistical degradation in all output bits, thus maximizing throughput compared to other processing techniques. Furthermore, the technique is applied to several fully digital chaotic oscillators with performance surpassing previously reported systems in the literature. The enhancement in the randomness is further examined in a simple image encryption application resulting in a better security performance. The system is verified through experiment on a Xilinx Virtex 4 FPGA with throughput up to 15.44 Gbit/s and logic utilization less than 0.84% for 32-bit implementations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.41-43
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• 2019

Image-to-image 변환에서 인상적인 성능을 보이는 StarGAN 은 모델의 성능에 중요한 영향을 끼치는 adversarial weight, classification weight, reconstruction weight 라는 세가지 하이퍼파라미터의 결정을 전제로 하고 있다. 본 연구에서는 이 중 conditional GAN loss 인 adversarial loss 와 classification loss 를 대치할 수 있는 attribute loss를 제안함으로써, adversarial weight와 classification weight 를 최적화하는 데 걸리는 시간을 attribute weight 의 최적화에 걸리는 시간으로 대체하여 하이퍼파라미터 탐색에 걸리는 시간을 획기적으로 줄일 수 있게 하였다. 제안하는 attribute loss 는 각 특징당 GAN 을 만들 때 각 GAN 의 loss 의 합으로, 이 GAN 들은 hidden layer 를 공유하기 때문에 연산량의 증가를 거의 가져오지 않는다. 또한 reconstruction loss 를 단순화시켜 연산량을 줄인 simplified content loss 를 제안한다. StarGAN 의 reconstruction loss 는 generator 를 2 번 통과하지만 simplified content loss 는 1 번만 통과하기 때문에 연산량이 줄어든다. 또한 이미지 Framing 을 통해 배경의 왜곡을 방지하고, 양방향 성장을 통해 학습 속도를 향상시킨 아키텍쳐를 제안한다.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1285-1295
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• 2008

A research on a simulator for a side walking path of a 16 degree-of-freedom (d.o.f) biped walking robot(BWR) which is composed of 4 d.o.f upper-part body and 12 d.o.f lower-part of the body is presented. For generation of stable side walking motion, the kinematics, dynamics and the zero moment of point(ZMP) of the BWR were analyzed analytically and included in the simulator. To operate the motion simulator for stable side walking of the BWR, a graphic user interface program was developed which needs inputs for the side distance between legs, base joint angle, walking type, and walking velocity. The simulator was developed to generate joint angle data of legs for side walking, and the data are transmitted to the BWR for stable side walking. In the simulator, a new path function for smooth walking motion was proposed and applied to the simulator and actual motion of a BWR. Also for actual side walking, an algorithm for estimating backlashes of the actuating joint motors was proposed and included in the simulator. To validate the performance of the proposed motion simulator, the simulator was operated and its side walking data of the simulator were generated for a period of side walking.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.1
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• pp.26-30
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• 2006

For the purpose of developing capacitive humidity sensor having interdigital electrodes, interdigital electrode was modeled and simulated to obtain capacitance and sensitivity as a function of geometric parameters like the structural gap and thickness. For the development of ASIC, switched capacitor signal processing circuits for capacitive humidity sensor were designed and simulated by Cadence using $0.25{\mu}m$ CMOS process parameters. The signal processing circuits are composed of amplifier for voltage gain control, and clock generator for sensor driving and switch control. The characteristics of the fabricated sensors are; 1) sensitivity is 9fF/%R.H., 2) temperature coefficient of offset(TCO) is $0.4%R.H./^{\circ}C$, 3) nonlinearity is 1.2%FS, 4) hysteresis is 1.5%FS in humidity range of $3%R.H.{\sim}98%R.H.$. The response time is 50 seconds in adsorption and 70 seconds in desorption. Fabricated process used in this capacitive humidity sensor having interdigital electrode are just as similar as conventional IC process technology. Therefore this can be easily mass produced with low cost, simple circuit and utilized in many applications for both industrial and environmental measurement and control system, such as monitoring system of environment, automobile, displayer, IC process room, and laboratory etc.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.683-686
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• 2001

This paper presents a novel prototype of the utility­interactive voltage source type sinewave pulse modulated power inverter using a high-frequency flyback transformer link. The proposed power conditioner circuit for the solar photovoltaic generation and small scale fuel cell has an isolation function due to the safety of the power processing system, which is more cost effective and acceptable for the small-scale distributed renewal energy conditioning and processing systems. The discontinuous current mode(DCM) of this power processing conversion circuit is applied to implement a simple circuit topology and pulse modulated control scheme. Its operation principle is described on the basis of simulation evaluations and theoretical considerations. The simulation results obtained herein prove that the proposed inverter outputs with sinusoidal waveforms and unity power factor currents are synchronized to the main voltage in utility power source grid. In this paper, the soft switching topology of high­frequency linked sinewave pulse modulation inverter is proposed and discussed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.192-196
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• 2010

Due to a development of a modem technology as Power Line Communication(PLC) over 200 Mbps, the high-speed multi-media data trasmission could be currently possible. The strength of the PLC has no more additional wiring work. PLC has also possible to high quality data transmission with currently electrical cable. It has a various strong point campare with existing wire and wireless communication technologies. In This paper we develop a high quality media transmitter-receiver based on merging the HomePlug AV, which is 200 Mbps class PLC technology and HDMI Interface technology. The video function was used for the VEDEO TEST GENERATOR in order to a property valuation. Smart Live 6 software were used for the assessment of audio property. As the result of measurement of the HD class images by capturing from the receiver of the PLC, the quality of images couldn't be confirm any deterioration, which has compared with original reflections. In case of audio part as the result of confirmation of the Phase, Magnitude, it has been confirmed that over 90% of nomal transmition and receiving of acoustic signal. It can be possible to have HD class Media service through the PLC.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1487-1493
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• 2013

A new simple control method for active power filter, which can realize the complete compensation of harmonics is proposed. In the proposed scheme, a model-based digital current control strategy is presented. The proposed control system is designed and implemented in a form referred to as internal model control structure. This method provides a convenient way for parameterizing the controller in term of the nominal system model, including time-delays. As a result, the resulting controller parameters are directly set based on the power circuit parameters, which make tuning of the controllers straightforward task. In the proposed control algorithm, overshoots and oscillations due to the computation time delay is prevented by explicit incorporating of the delay in the controller transfer function. In addition, a new compensating current reference generator employing resonance model implemented by a DSP(Digital Signal Processor) is introduced. Resonance model has an infinite gain at resonant frequency, and it exhibits a band-pass filter. Consequently, the difference between the instantaneous load current and the output of this model is the current reference signal for the harmonic compensation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.10
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• pp.1421-1424
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• 2013

The electronic equipment which is exposed to high level pulsed radiation is damaged by Upset, Latchup, and Burnout. Those damages come from the instantaneous photocurrent from electron-hole pairs generated in itself. Such damages appear as losses of a power in military weapon system or as a blackout in aerospace equipment and eventually caused in gross loss of national power. In this paper, we have implemented a RDC(Radiation detection and control module) as a part of the radiation protection technology of the electronic equipment or devices from the pulsed gamma radiation. The RDC, which is composed of pulsed gamma-ray detection sensor, signal processors, and pulse generator, is designed to protect the an important electronic circuits from the a pulse radiation. To verify the functionality of the RDC, LM118s, which had damaged by the pulse radiation, were tested. The test results showed that the test sample applied with the RDC was worked well in spite of the irradiation of a pulse radiation. Through the experiments we could confirm that the radiation protection technology implemented with the RDC had the functionality of radiation protection for the electronic devices.