• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.72-75
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• 2012

A solar array makes a Solar Array Regulator (SAR) for Low-Earth-Orbit satellite have different small signal characteristic. Therefore, an Average-Current-Mode (ACM) controller cannot control the BUCK-BOOST type SAR which operates in a current region of the solar array. In this paper, we present the Pseudo-Continuous Current Mode (PCCM) BUCK-BOOST Type SAR which can be controller by the ACM Controller. We explain the circuit operation of the PCCM BUCK-BOOST Type SAR, derive its small signal transfer function and design ACM Controller. Finally, we verify the ACM control of the PCCM BUCK-BOOST Type SAR by using a simulation.

• Journal of KIISE
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• v.41 no.12
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• pp.1050-1057
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• 2014

Electroencephalogram (EEG)-based brain-computer interfaces (BCI) can be used for a number of purposes in a variety of industries, such as to replace body parts like hands and feet or to improve user convenience. In this paper, we propose a method to decompose and extract motor imagery EEG signal using Empirical Mode Decomposition (EMD) and Fast Fourier Transforms (FFT). The EEG signal classification consists of the following three steps. First, during signal decomposition, the EMD is used to generate Intrinsic Mode Functions (IMFs) from the EEG signal. Then during feature extraction, the power spectral density (PSD) is used to identify the frequency band of the IMFs generated. The FFT is used to extract the features for motor imagery from an IMF that includes mu rhythm. Finally, during classification, the Support Vector Machine (SVM) is used to classify the features of the motor imagery EEG signal. 10-fold cross-validation was then used to estimate the generalization capability of the given classifier., and the results show that the proposed method has an accuracy of 84.50% which is higher than that of other methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.875-877
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• 2011

This paper introduces a touch screen panel driver using modified charge pump circuit. The touch screen panel driver is composed of an analog circuit part which senses a touch and a digital circuit which analyse the sensed signal. To verify the functions the touch screen panel driver, a mixed-mode circuit was built and simulated using Cadence Spectre. The digital circuits were modeled with Verilog-A in order to interface with the analog circuits and verify the functionalities of the driver with less simulation time. From the simulation results, we can verify the reliable operations of the simple structured touch screen panel driver which does not include an ADC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.196-198
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• 2007

본 논문에서는 가전 및 사무용 전원장치가 대기모드 상태에 있는 경우의 전력소모를 줄일 수 있는 PWM(Pulse Width Modulation) IC를 설계하였다. 설계된 PWM IC는 전원장치가 정상상태에서 동작하는 경우 전원장치 출력단에서 피드백 받은 신호의 크기에 따라 40 ~ 60kHz의 구동 주파수를 가지는 스위칭 소자 구동 신호를 내보내고, 대기모드 상태에서 동작하는 경우에는 최소 33KHz의 주파수를 가지는 신호를 내보내도록 설계되었다. 각각의 경우에 스위칭 소자 구동 신호의 듀티비는 정상상태인 경우에는 20 ~ 88%, 대기모드 상태인 경우에는 1%이내가 되도록 설계하였다. 시뮬레이션을 통해 검증한 결과 대기모드 상태에서 전원장치의 전력소모량은 0.2W 정도로 작게 나타남을 확인하였다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.6
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• pp.578-583
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• 2016

In this paper, we propose a multi-mode wireless power transfer (WPT) system with a dual loop structure. The proposed multi-mode WPT system consist of outer loop module which can operate at two different frequency bands including 6.78 MHz magnetic resonance WPT mode and 13.56 MHz near field communication (NFC) mode and inner loop module connected with outer loop which can operate at two different frequency bands including WPC mode and PMA mode based on inductive coupling standards. In order to be able to embed this system into smartphone battery back cover, the electrical designs are optimized and then the size was fixed $45{\times}90{\times}0.35mm3$ (including ferrite sheet) which is the same commercial smartphone. The proposed multi-mode WPT module can cover WPC and PMA mode based on inductive coupling. Moreover, it has more than 20 dB return loss characteristics at two different frequency bands including 6.78 MHz and 13.56 MHz, and shows more than 70 % transfer efficiency between resonant coils at 6.78 MHz in magnetic resonant charging environment.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.59-65
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• 2014

In this paper, in order to improve efficiency performance of power amplifiers, a mode changeable autotransformer is proposed. Efficiency performance at the low-power mode can be improved by adopting the mode changeable autotransformer. A dual-mode autotransfomrer CMOS power amplifier using a standard 0.18-${\mu}m$ CMOS process is designed in this work. Number of turns in a primary winding is re-configurated according to mode change between the high-power mode and the low-power mode. Thus, the efficiency performance of the power amplifier at each mode is optimized. EM and total circuit simulation results verify that low-power mode power added efficiency(PAE) at 24dBm output power is improved from 10.4% to 26.1% using the proposed multi-mode operation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.269-274
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• 2004

In this paper, proposed is the dual-mode algorithm of blind decision feedback equalizer (DFE) for digital terrestrial television signals. According to channel impairments, the proposed dual-mode algorithm for blind DFE operates in decision-directed mode or in blind mode of operation. The error signals being used in tap update of the equalizer are generated in the best mode of operations, so that the confidence of equalizer tap coefficient update is more accurate. As a result, it is possible to track the channel characteristics variations by automatic switching over between two modes of operations. For 8-level vestigial sideband modulated digital television signals, the mean square errors and symbol error rates of the proposed algorithm are compared with those of conventional methods. And the usability of the proposed scheme is assessed by computer simulations under various static and dynamic multipath channel environments.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.81-82
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• 2012

본 논문은 고효율 획득 및 입력전류 리플 저감을 위한 3상 부스트 컨버터의 동작 알고리즘을 제안한다. 입력전압별로 인덕터 전류에 따른 투자율 감소를 고려하여 DCM 및 BCM 동작시의 효율과 입력 전류 리플을 수식적으로 분석한다. 이에 따라 3상 부스트 컨버터를 경계 도통 모드+불연속 도통 모드의 혼합 모드에서 동작시키고 타당성을 실험을 통해 검증한다.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.18-19
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• 2013

본 논문에서는 Energy storage system을 위한 양방향 DC-to-DC 컨버터를 제안한다. 제안된 양방향 DC-to-DC 컨버터는 플라이백 컨버터와 벅 컨버터를 결합한 구조로, 벅 컨버터의 인덕터는 플라이백 컨버터의 변압기 1차측으로 대체된다. 벅 컨버터의 인덕터를 변압기 1차측으로 대체함으로써 소자의 수를 줄이고, 변압기를 이용함으로써 턴수비에 따른 높은 출력값을 얻을 수 있다. 전력 수요가 적을 시 강압 모드로 동작하여 전력을 저장해 두었다가 전력이 필요한 시점에 승압모드로 동작하여 필요 에너지를 제공한다. 제안된 컨버터의 동작 모드에 따른 이론적 분석을 시행하고 PSIM을 이용한 시뮬레이션을 통해 타당성을 검증한다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.760-762
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• 2005

본 논문은 TCP 기반의 인터렉티브 응용 프로그램을 대상으로 무선 네트워크 인터페이스 카드의 전력 소모를 최소화할 수 있는 기법을 제안한다. 네트워크를 사용하는 응용 프로그램은 각각 다른 트래픽 특성을 보이기 때문에 최적의 동작 모드를 결정하는 데 동일한 판단 기준을 적용하기 어렵다. 인터렉티브 응용 프로그램은 사용자의 요청에 따라 트래픽이 발생하는 특징이 있기 때문에 트래픽 발생 주기 및 트래픽의 과다한 정도를 측정하고 이를 기준으로 최적의 동작 모드를 결정할 수 있다. 본 논문에서는 인터렉티브 응용 프로그램의 특성을 구별하는 기준을 제시하고 이를 기반으로 최적의 동작 모드를 결정하는 알고리즘을 제안한다.