• 수산해양기술연구
• /
• 제35권3호
• /
• pp.328-334
• /
• 1999

A fish pump makes very important roles in an automation system of an aquaculture farm, thus it has been used widely in order to transfer fishes from one place to the other place automatically. In spite of its significant roles, the efforts for developing performance and promoting efficiency of the fish pump are not sufficient yet. In this paper, a method which makes the fish pump automation system is suggested. Automation of the fish pump can be accomplished by using variable voltage and variable frequency inverter system including induction motors. Especially, very simple logic to generate Pulse width Modulation(PWM) wave to control induction motor efficiently and three steps speed control method to regulate liquid quantity of the fish pump simply are suggested. Owing to the simplifies speed control and PWM wave generation technique, a cheaper microprocessor, 80C196KC, than a digital signal Processor(DSP) can be used to operate control algorithm in induction motor systems for real time control Also, a new idea of remote control for the simplifies novel inverter system by Programmable logic Controller(PLC) without special output unit, digital to analog converter(D/A), is suggested in this paper. Consequently the function of reliability, availability and serviceability of the fish pump system are developed. It will be expected to contribute expanding of application of the fish pump in aquaculture farms because the system can reduce energy consumption and some difficulties according to manual operation prominently.

• Journal of Power Electronics
• /
• 제10권2호
• /
• pp.132-137
• /
• 2010

Interleaving techniques are widely used to reduce input/output ripples and to increase the power capacity of boost converters operating in critical conduction mode. Two types of phase-shift control schemes are studied in this paper, the turn-on time shifting method and the turn-off time shifting method. It is found that although the turn-off time shifting method exhibits better performance, it suffers from sub-harmonic oscillations at high input voltages. To solve this problem, an intensive quantitative analysis of the sub-harmonic oscillation phenomenon is made in this paper. Based upon that, a novel modified turn off time shifting control scheme for interleaved boost converters operating in critical conduction mode is proposed. An important advantage of this scheme is that both the master phase and the slave phase can operate stably in critical conduction mode without any oscillations in the full input voltage range. This method is implemented with a FPGA based digital PWM control platform, and tests were carried out on a two-phase interleaved boost PFC converter prototype. Experimental results demonstrated the feasibility and performance of the proposed phase-shift control scheme.

• Journal of Semiconductor Engineering
• /
• 제2권1호
• /
• pp.109-118
• /
• 2021

This review paper describes the overall operating principle of a discrete-time delta-sigma modulator (DTDSM) and a continuous-time delta-sigma modulator (CTDSM) using a switched-capacitor (SC). In addition, research that has solved the problems related to each delta-sigma modulator (DSM) is introduced, and the latest developments are explained. This paper describes the chopper-stabilization technique that mitigates flicker noise, which is crucial for the DSM. In the case of DTDSM, this paper addresses the problems that arise when using SC circuits and explains the importance of the operational transconductance amplifier performance of the first integrator of the DSM. In the case of CTDSM, research that has reduced power consumption, and addresses the problems of clock jitter and excess loop delay is described. The recent developments of the analog front end, which have become important due to the increasing use of wireless sensors, is also described. In addition, this paper presents the advantages and disadvantages of the three-opamp instrumentation amplifier (IA), current feedback IA (CFIA), resistive feedback IA, and capacitively coupled IA (CCIA) methods for implementing instrumentation amplifiers in AFEs.

• Nuclear Engineering and Technology
• /
• 제53권10호
• /
• pp.3406-3412
• /
• 2021

A real-time digital time-stamp sorting algorithm used in the In-Beam positron emission tomography (In-Beam PET) is presented. The algorithm is operated in the field programmable gate array (FPGA) and a small amount of registers, MUX and memory cells are used. It is developed for sorting the data of annihilation event from front-end circuits, so as to identify the coincidence events efficiently in a large amount of data. In the In-Beam PET, each annihilation event is detected by the detector array and digitized by the analog to digital converter (ADC) in Data Acquisition Unit (DAQU), with a resolution of 14 bits and sampling rate of 50 MS/s. Test and preliminary operation have been implemented, it can perform a sorting operation under the event count rate up to 1 MHz per channel, and support four channels in total, count rate up to 4 MHz. The performance of this algorithm has been verified by pulse generator and ²²Na radiation source, which can sort the events with chaotic order into chronological order completely. The application of this algorithm provides not only an efficient solution for selection of coincidence events, but also a design of electronic circuit with a small-scale structure.

• 한국전자파학회논문지
• /
• 제22권9호
• /
• pp.833-839
• /
• 2011

본 논문에서는 다양한 변조 신호에 대한 1.8 GHz 대역 VSWR을 구하는 방법을 제시하였다. 방향성 결합기를 이용하여 입사 전력과 반사 전력을 측정하였으며, 측정 회로 크기와 비용을 최소화하기 위해 SPDT(Single Pole Double Throw) 스위치를 사용하여 한 개의 검파기와 한 개의 AD(Analog to Digital) 변환기로 회로 구현이 가능하게 되었다. MCU(Micro Control Unit)를 이용하여 전압 반사 계수와 VSWR을 계산하였으며, 다양한 변조 신호에 대한 측정오차를 줄이고 MCU의 처리 시간 및 부하를 최소화하기 위해, 간단한 버블정렬 알고리즘을 적용하여 비적용한 경우보다 0.2의 VSWR 오차를 개선할 수 있었다.

• 한국산학기술학회논문지
• /
• 제5권1호
• /
• pp.60-64
• /
• 2004

32비트 RISC 프로세서인 PXA255기반 보드에 임베디드 리눅스 운영체제와 HTTP(Hyperfext Transfer Protocol) 웹서버를 포팅하여 사용자의 웹 브라우져 상에서 원격지 가택에 대한 실시간 감시가 가능한 시스템을 구현하였다. 웹 서버는 GoAhead 웹 서버2.1 버전을 교차 컴파일하여 사용하였으며 가택감시를 위한 아날로그 신호에 대한 입력을 프로세서가 받기 위해 ADC(Analog to Digital Convertor)칩인 ADC0809를 사용하였다 ADC를 위한 디바이스 드라이버를 작성하였으며 이를 웹 브라우져 상에서 실시간적으로 변하는 데이터를 모니터링하기위해 클라이언트 풀(Clieilt Pull)방식을 사용한 CGI-C 응용프로그램을 개발하였다. 감시가 가능한 요소로는 온도, 조도 그리고 가스 유출여부이며 가스 밸브와 현관문의 개폐상태를 확인할 수 있게 하였고 긴급 상황 발생시 경고음을 발생하도록 하였다 최근 홈 디지털 서비스 중에 사용자가 가장 필요로 하는 긴급 상황에 대한 감시 요구를 내장형 시스템을 사용하여 보다 적은비용으로 구현하였다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• 제2B권3호
• /
• pp.109-114
• /
• 2002

This paper analysis the transient performance of the modified excitation system using 4-quadrant chopper for a synchronous machine connected to HVDC system. Conventionally, capacitors are used to supply reactive power requirement at a strong converter bus. And the installation of a synchronous machine is essential in an isolated weak network to re-start after a shutdown of HVDC and to increase the system strength. However, a conventional static excitation system has some problems which are harmonic instability and the system stress due to overvoltage. To reduce these problems, the new excitation system, which has 4-quadrant chopper, is proposed. As the proposed system provides the capability to allow reverse current and isolate between AC network and excitation power, problems of overvoltage and harmonic instability can be solved. The investigation is performed and confirmed by the time domain digital simulation using PSCAD/EMTDC program.

• 디지털콘텐츠학회 논문지
• /
• 제13권1호
• /
• pp.31-36
• /
• 2012

국가 지리 정보 시스템에 의해 국가 기본 지형도가 DXF 포맷으로 제작되어 있고, CAD로 작성된 정보들이 풍부하며 스캐너를 이용하여 쉽게 데이터를 획득 가능함으로 기존의 DXF 파일의 수입은 비용과 시간을 절약한다. 또한, 지형도와 같은 공간 데이터를 GIS를 위한 중간 파일인 PostScript와 같은 포맷으로 변환하여 다른 시스템으로 수출이 가능하도록 하여야 한다. 이를 위해, 본 논문에서는 DXF 포맷으로 작성된 파일을 MVF로 수입하고, 다시 PostScript로 수출하기 위하여 공간 객체 변환기를 구성하는 3개의 단위 모듈인 파일 처리 모듈, MVF 수입 모듈, 그리고 MVF 수출 모듈들을 설계 및 구현하였다. 그리고 DXF 파일로 되어 있는 지형도에 대해서 실제 변환을 검증해 보았다.

• 한국통신학회논문지
• /
• 제33권9A호
• /
• pp.882-890
• /
• 2008

본 논문은 ADC(analog-to-digital converter)의 속도에 의한 시간 영역에서 채널 추정 한계를 극복하기 위해서 트레이닝(training) 신호의 주파수 성분을 이용해서 다중경로 채널을 추정하고 이를 이용해서 채널 왜곡을 보상하는 BPM(biphase modulation)-UWB 수신기를 제안한다. 여러 개의 펄스로 구성된 펄스열의 주기적인 특성을 이용해서 효과적으로 채널 추정이 가능함을 수학적으로 보인다. 또한 추정된 채널 주파수 응답 정보를 이용해서 시스템 성능을 최적화시킬 수 있는 디지털 수신부 구조를 제시하며 BER성능을 유도한다. 시뮬레이션을 통해 제시된 방법이 다중경로 채널을 보상함으로써 수신기의 BER성능이 획기적으로 개선됨을 보인다.

• 전기학회논문지
• /
• 제66권1호
• /
• pp.48-54
• /
• 2017

In this paper, hysteresis voltage control method is proposed to an unidirectional inverter control for piezoelectric load. Piezoelectric load has electrically RC characteristic, and is driven by the inverter to control the output voltage waveform. When controling the output waveform by PI control, appropriate gains need to be selected. However, hysteresis control may minimize the output distortion because it has maximum proportional gain. In addition, Hysteresis control algorithm has simple structure to realize and the response is fast. Although the switching frequency of the inverter by hysteresis control varies, the switching frequency for the piezoelectric load is lower than that by PI control for equivalent performance. In particular, on implementing the algorithm using FPGA, the algorithm can be implemented in fewer pabrics and the processing time can be reduced. The superiority of the proposed hysteresis voltage control was proved for piezoelectric load through simulation and experiment.