• Journal of electromagnetic engineering and science
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• v.17 no.1
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• pp.39-43
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• 2017

In this paper, a systematic and statistical calibration technique was implemented to calibrate a high-speed signal converting system containing multiple digital-to-analog converters (DACs). The systematic error (especially the imbalance between DACs) in the current combining network of the multi-DAC system was modeled and corrected by calculating the path coefficients for individual DACs with wideband reference signals. Furthermore, by applying a Kalman filter to suppress noise from quantization and clock jitter, accurate coefficients with minimum noise were identified. For correcting an arbitrary waveform generator with two DACs, a co-simulation platform was implemented to estimate the system degradation and its corrected performance. Simulation results showed that after correction with 4.8 Gbps QAM signal, the signal-to-noise-ratio improved by approximately 4.5 dB and the error-vector-magnitude improved from 4.1% to 1.12% over 0.96 GHz bandwidth.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.4
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• pp.53-58
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• 2009

In recently years, the research and application for sensor has increased in each field. In this paper, the system which can perceive and detect using 3-axis accelerometer sensor and serial communication is proposed. Also, the user has GUI environment for monitor in real-time. In order to reduce unstable data and error defect of electronic rechargeable liquid tilt sensor used digital 3-axis accelerometer sensor which has AD convertor. Therefore, this system provide exact data and a problem of objects for user more easier.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.5
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• pp.111-116
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• 1998

In this paper, we proposed method of performance enhancement of the ultrasonic imaging system using quadrature detector and implementation of the software quandrature detector. Since the quadrature detector is more sensitive than the enbelope detector of the conventional ultrasonic imaging syustem, we are able to achieve the contrast enhnacement. Although hardware quadrature detector is able to process high sped data acquisition, its hardware has complexity. In order to show the performance of the software quadrature we have constructed ultrasonic signal processing system and obtained the reflected signal from the aluminum specimen using A/D convertor. Our experimental results showed that image of the quadrature detector is better than that of the envelope detector.

• KSBB Journal
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• v.13 no.4
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• pp.461-467
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• 1998

A fermentation system was supplemented with a device for the measurement of the durations of alkali pump feeding for automatic pH control and an A/D convertor for precise monitoring of pH value by computer. A software program was developed to measure buffer capacities from the pH signal and the pH control signal during fermentation. By measuring the buffer capacity on-line, levels of acetic acid were estimated by a software sensor using pH signal in a fermentation process of E.coli growing in a minimal medium. The measured values of acetic acid showed correlation to those of estimated by the software sensor. Lacitic acid production was also successfully estimated by the values of buffer capacities measured on-line.

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.33-43
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• 2000

Up-conversion of rare-earth element added glass is promising area for short wavelength laser source by utilizing high power semiconductor infra-red laser if the efficiency can be increased by proper method. In this study, relatively low phonon energy fluoride glasses were prepared by co-doping rare-earth elements to realize the high efficiency up-convertor. The physical, chemical, andoptical properties of co-doped fluoride glasses were measured. 10 combinations of 5 different rare-earth fluoride elements doped samples were prepared and their transition temperatures, chemical durability, density, hardness, refractive index, absorption, fluorescence, and fluorescence lifetime were measured. 480nm wavelengths blue up-conversion was found in the Yb3+/Tm3+ co-doped glass sample with 800nm laser source and the optimum composition for the most efficient blue up-conversion was found from the glass sample with 0.3 mol% TmF3 and 1 mol% YbF3.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.1
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• pp.47-53
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• 2006

In this paper, a simple scheme compensating for the effect of dc-link ripple voltages on output voltage of two-leg and three-phase PWM inverters is proposed, where single-phase half-bridge PWM convertor and two-leg inverter are used. The voltage at neutral point of the dc-link is controlled so that the upper-half of do-link voltage is equal to the lower-half voltage in average concept. However, the effect of the do-link ripple voltage results in the inverter output voltage and current distortion. This effect can be eliminated by introducing a compensation voltage in switching time calculation. Also, the inverter dead time should be compensated for sinusoidal output waveform. The proposed scheme has been verified by experimental results which were obtained from the V/F constant operation of the induction motor fed by two-leg inverter.

• The Transactions of the Korea Information Processing Society
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• v.5 no.3
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• pp.583-591
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• 1998

본 논문은 한자·한글 혼합 문서들을 정확한 우리말 문서로 자동 변환하는 한자·한글 변환기를 설계하고 구현한다. 구현된 한자·한글 변환기는 정보 검색 시스템에서 한자·한글 혼합 문서 검색시 사용자들이 한자에 해당하는 한글음을 파악하는데 걸리는 시간을 절약하고 쉽게 판독할 수 있도록 한다. 이를 위해 KS C 5601 표준코드를 기준으로 바르지 못한 한글음 생성의 원인을 조사하고 두 개 이상의 한글음을 갖는 한자들과 이형표기가 가능한 한자를 올바른 한글음으로 변환할 수 있는 한글단어 매핑사전을 구축한다.

• Journal of Power Electronics
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• v.15 no.1
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• pp.235-245
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• 2015

This paper proposes a reactive current assignment and control strategy for a doubly-fed induction generator (DFIG) based wind-turbine generation system under generic grid voltage sag or swell conditions. The system's active and reactive power constrains during grid faults are investigated with both the grid- and rotor-side convertors (GSC and RSC) maximum ampere limits considered. To meet the latest grid codes, especially the low- and high-voltage ride-through (LVRT and HVRT) requirements, an adaptive reactive current control scheme is investigated. In addition, a torque-oscillation suppression technique is designed to reduce the mechanism stress on turbine systems caused by intensive voltage variations. Simulation and experiment studies demonstrate the feasibility and effectiveness of the proposed control scheme to enhance the fault ride-through (FRT) capability of DFIG-based wind turbines during violent changes in grid voltage.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.555-556
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• 2007

This paper proposes a new concept's IDSFHA(Intelligent Digital Switchgear For Home Automation) which can obtain the safety, the reliability and the easy to correspond to the request of the general electric customer or electric power company under the ubiquitous-based home automation environments The IDSFHA is designed by analyzing their requirement functions, a 32-bit micro processor is adopted as main controller to support efficiently the designed functions. The single phase power IC(ADE7753) is utilized to collect the electric power information, and makes it possible to communicate as internet among the IDSFHA and their using the ethernet convertor. In the proposed IDSFHA, the several functions are implemented such as the earth leakage level display and waveform transmitting, the electric power using fee display, voltage management, load management and load control function. Finally, the prototype of the IDSFHA is made experimently based on the designed results.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.431-432
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• 2012

The proposed dc-dc convertor for a battery energy storage system(BESS) can reduce the power rating and bidirectional power flow. This system consist soft-switching bidirectional dc-dc converter so it can reduce the energy loss when charging and discharging mode. Thus it can achieve high efficiency. Also, overall system utilizes the voltage compensation circuit. It is composed of small size and low cost due to reducing the power rating. In this paper, we proposed system about verified by simulation.