• 대한기계학회논문집B
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• 제30권2호
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• pp.110-116
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• 2006

A syringe pump or a device using high electric voltage has been used for controlling flows inside a LOC (lab-on-a-chip). Compared to LOC, however, these microfluidic devices are large and heavy that they are burdensome for a portable ${\mu}-TAS$ (micro total analysis system). In this study, a new flow control technique employing pressure regulators and pressure chambers was developed. This technique utilizes compressed air to control the micro-scale flow inside a LOC, instead of a mechanical actuator or an electric power supply. The pressure regulator controls the output air pressure by adjusting the variable resistor attached. We checked the feasibility of this system by measuring the flow rate inside a capillary tube of $100{\mu}m$ diameter in the Re numbers ranged from 0.5 to 50. In addition, the performance of this flow control system was compared with that of a conventional syringe pump. The developed flow control system was found to show superior performance, compared with the syringe pump. It maintains automatically the: air pressure inside a pressure chamber whether the flow inside the capillary tube is on or off. Since the flow rate is nearly proportional to the resistance, we can control flow in multiple microchannels precisely. However, the syringe pump shows large variation of flow rate when the fluid flow is blocked in the microchannel.

• 전자공학회논문지
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• 제50권12호
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• pp.63-70
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• 2013

본 논문은 외부 커패시터 없이 광범위 하게 높은 전원 공급 잡음 제거비(PSRR)을 갖는 선형 정류기(LDO)에 관한 것이다. 제안된 LDO는 높은 PSRR과 안정도를 유지하기 하기 위해 nested Miller 보상 기술을 사용하였고, 내부적으로 캐스코드(cascode) 보상과 전류버퍼(current buffer) 보상 기술을 사용하였다. 또한 외부의 부하 커패시터가 없기 때문에 외부 하드웨어 비용을 최소화 하였고, 제안된 보상 기법을 사용하여 내부에 작은 커패시터를 사용하고도 안정도를 확보할 수 있었다. 설계된 LDO는 2.5V~4.5V의 입력 전압을 받아서 1.8V의 전압을 출력하고 최대 10mA의 부하 전류를 구동할 수 있다. 일반 0.18um CMOS 공정을 이용하여 제작하였고 면적은 300um X 120um 이다. 측정된 PSRR은 DC일 때 -76dB, 1MHz일 때 -43dB를 만족한다. 동작 전류는 25uA를 소모한다.

• 한국인터넷방송통신학회논문지
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• 제20권5호
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• pp.71-77
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• 2020

최근 추적 레이더는 다양한 환경에서 여러 가지 제약을 받지 않고 운용이 가능한 소형 추적 레이더 개발의 필요성을 확인하였다. 또한 소형 추적 레이더의 성능은 기존 추적 레이더와 동등 이상을 요구한다. 이런 소형 추적 레이더는 기존 추적 레이더의 소형화와 저전력화를 통해 구현할 수 있다. 본 논문에서는 소형 추적 레이더를 위한 신호처리기의 역할과 기능을 정의하고, 소형 추적 레이더를 위한 신호처리기를 구현하기 위해 필요한 디바이스 사용의 최소화를 통한 소형화와 소비 전력의 효율을 높이기 위한 방안을 제안하였다. 소형화에 대한 방안으로 상용 DDC, 통신 controller등의 디바이스 기능을 FPGA에 구현하여 소형 추적 레이더를 위한 신호처리기를 설계하였다. 또한 효율이 좋은 Switching regulator를 사용한 전원부의 설계로 저전력 신호처리기를 설계하였다. 마지막으로 구현한 소형 추적 레이더를 위한 신호처리기의 성능시험과 소형 추적 레이더에 신호처리기를 적용한 도플러 추적 시험, 거리 추적 시험으로 신호처리기를 검증하였다.

• 제어로봇시스템학회논문지
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• 제17권7호
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• pp.685-696
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• 2011

An efficient laparoscope manipulator robot was designed to automatically control the position of laparoscope via a passive joint on end-effector position. The end position of the manipulator is controlled to have corresponding velocity defined in the global coordinate space using laparoscopic visual information. Desired spatial position of laparoscope was derived from detected positions of surgical instrument tips, then the clinical viewing plane was moved by visual servoing task. The laparoscope manipulator is advantageous for automatically maintaining clinically important views in the laparoscopic image without any additional operator. A laparoscope is mounted to a holder which is linked to four degree of freedom manipulator via universal joint-type passive rings connection. No change in the design of laparoscope or manipulator is necessary for its application to surgery assistant robot system. Expanded working space and surgical efficiency were accomplished by implementing slant linking structure between laparoscope and manipulator. To ensure reliable positioning accuracy and controllability, the motion of laparoscope in an abdominal space through trocar was inspected using geometrical analysis. A designed laparoscope manipulating robot system can be easily set up and controlled in an operation room since it has a few subsidiary devices such as a laparoscope light source regulator, a control PC, and a power supply.

• 전기학회논문지
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• 제65권11호
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• pp.1827-1834
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• 2016

This paper presents a high efficient generator with PM(Permanent Magnet) exciter. The proposed PM exciter for the generator can produce a linear output voltage according to the engine speed. This output voltage is directly used to control the field current of the generator to adjust the generator output voltage. In the proposed generator system, since the field winding current can be supplied by the PM exciter, the generator can self-start without any battery or an external power supply due to the low residential flux. Furthermore, the operating efficiency of the generator is higher than a conventional winding exciter. The main problem of the proposed generator system, the field winding current controller has to be embedded inside the generator, and it rotates according to the generator shaft. In this paper, the proper embedded current controller is designed for the proposed generator system. Due to the embedded controller cannot be connected to the outside the generator controller, the measured instantaneous output voltage of the generator is transferred by the photo isolated communication using shaft aligned infrared transmitter and receiver to keep the constant generator output voltage. In this paper, 10kW, 380V engine generator with PM exciter and the embedded DAVR(Digital Automatic Voltage Regulator) are described. The proposed high efficiency generator is simulated and tested to verify the effectiveness.

• 한국안전학회지
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• 제26권6호
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• pp.13-19
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• 2011

The purpose of this study is to examine the cause of damage to electrolytic capacitors and to present the heat generation mechanism in order to prevent the occurrence of similar problems. From the analysis results of electrolytic capacitors collected from accident sites, the fire causing area can be limited to the primary power supply for the initial accident. From the tests performed by applying overvoltage, surge, etc., it is thought that the fuse, varistor, etc., are not directly related to the accidents that occurred. The analysis of the characteristics using a switching regulator showed that the charge and discharge characteristics fell short of standard values. In addition, it is thought that heated electrolytic capacitors caused thermal stress to nearby resistances, elements, etc. It can be seen that the heat generation is governed by the over-ripple current, application of AC overvoltage, surge input, internal temperature increase, defective airtightness, etc. Therefore, when designing an electrolytic capacitor, it is necessary to comprehensively consider the correct polarity arrangement, appropriate voltage application, correct connection of equivalent series resistance(ESR) and equivalent series inductance(SEL), rapid charge and discharge control, sufficient margin of dielectric tangent, etc.

• 한국항해항만학회지
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• 제47권2호
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• pp.85-92
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• 2023

The hardware of an LED lighting control system for coastal lighting at coastal pier entrance consists of a power supply unit, an AVR control unit, a CLCD output unit, an LED control unit, a scenario selection switch unit, and an operation speed display unit. It is made of an 8-channel. The CPU used ATmega128 and the FET was used to control the current signal. To operate the CPU, DC 12V was converted to DC 5V using a regulator 7805. A heat sink was used to remove heat generated in the FET. By connecting the load LED module to the manufactured 8-channel LED lighting control system, the operation was confirmed through various production scenarios. In addition, a control system was designed to show the most suitable color for the atmosphere of the coastal pier according to the input value of temperature and illumination using a fuzzy control system. Computer simulation was then conducted. Results confirmed that fuzzy control did not need to store many data inputs due to characteristics of artificial intelligence and that it could efficiently represent many output values with simple fuzzy rules.

• 한국항공우주학회지
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• 제36권12호
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• pp.1207-1215
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• 2008

우주환경에서 운용되는 위성은 상호 유기적으로 연결된 다양한 전자장비에서 방출하는 전도성/복사성 에너지 결합에 의해 다양한 잡음 신호를 발생하게 되는데, 이러한 잡음은 탑재체를 포함한 위성 시스템과 발사체의 전자기적인 영향에 의하여 주요 기능에 중대한 결함을 유발시킬 수 있다. 이에 위성 시스템은 개발 단계에서부터 전자파환경에 대한 영향을 최소화하기 위한 시스템 설계 검증이 요구된다. 위성 시스템에서 검증하여야 하는 전자파 환경 요소는 위성으로부터 방출되는 전도성/복사성 잡음과 이러한 잡음 환경에서 위성의 정상운용을 검증하는 감응성 잡음이 있다. 통신해양기상위성 시스템의 전자파 호환성 설계 검증은 PSR의 출력을 각 유닛에 분배하는 과정에서 전원선에서 방출하는 전도성 방출특성을 측정하여 시스템에서 통제하는 전자파 규격에 적합한지를 검증하고, 이러한 방출 레벨로부터 6 dB 시스템 안전성마진을 고려한 레벨의 전도성 잡음을 전원선에 인가하여 시스템의 성능을 검증하는 것이다. 아울러, 각 유닛의 전자파 복사 특성을 종합하여 시스템 수준의 복사성 잡음 수준을 예측하고 발사체 요구 규격과의 적합성을 분석하는 것이다. 본 논문에서는 통신해양기상위성의 전자파 환경시험 결과를 토대로 시스템 수준의 전자파 호환 특성 및 발사체와의 적합성 분석 결과를 제시하였으며, 잡음요소 분석 결과는 FM EMC 시험에 반영될 것이다.

• 한국토양비료학회지
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• 제47권6호
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• pp.425-431
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• 2014

Most fields in highland areas are covered with rye or hairy vetch for conservation during a fallow. However, using cover crops needs an effort to sow, and this makes top soil more vulnerable to loss due to surface disturbances. The aims of this study were to develop an automatic seeding-regulator device using a low-price, extensive-use GPS sensors and a DC motors and to evaluate a working efficiency of it after adaptation to partial tillage machine for reducing seeding effort. The amount of runoff water and soil loss was evaluated with partial tillage and simultaneous-seeding after harvesting soybean, in 17% slope lysimeters. In results, the seeding amount with the machine speed was stable between $0.5{\sim}0.8m\;s^{-1}$ of working sections. The automatic control device of seeding-rate could be enough to solve the slip problems of power selecting supply system or five four-wheel drive device. In partial tillage and simultaneous seeding, runoff water was 11.6% ($1.8m^3ha^{-1}$) of the scatter-seeding control ($15.5m^3ha^{-1}$) and soil loss was 13.2% ($7kg\;ha^{-1}$) of the scatter-seeding control ($53kg\;ha^{-1}$). These results suggest that partial tillage and simultaneous-seeding methods are very effective in decreasing work effort and soil loss of sloped land.

• 한국정보통신학회논문지
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• 제20권1호
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• pp.110-116
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• 2016

본 논문에서는 디지털 임피던스 보정 회로와 이퀄라이저 회로를 가진 1.2V 5Gb/s SLVS 차동 송신단을 제안한다. 제안하는 송신단은 4-위상 출력 클록을 갖는 위상 고정 루프, 4-to-1 직렬변환기, 레귤레이터, 출력 드라이버, 그리고 신호보존성을 향상하기 위한 이퀄라이저 회로를 포함한다. 또한, built-in self-test를 위해 pseudo random bit sequence 발생기를 함께 구현한다. 제안하는 SLVS 송신단은 80mV에서 500mV의 차동 출력 전압범위를 지원한다. SLVS 송신단은 1.2V의 공급전압을 가지는 65nm CMOS공정을 이용하여 구현한다. 측정된 5Gb/s SLVS 송신단의 peak-to-peak 시간 지터는 46.67ps이며, 전력소모는 1.88mW/Gb/s이다.