• Journal of Energy Engineering
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• v.11 no.1
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• pp.74-80
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• 2002

In this study, a numerical method for fuel droplet evaporation in cylinder of S.I. engine is presented. This study was newly defined non-dimensional critical droplet lifetime and modeled heating and evaporation processes of fuel droplet during intake and compression stroke of gasoline engine. The simulation results show that simultaneous increase of gas temperature and pressure in compression stroke seems to have compensative effect on droplet gasification rate. The environment variations in cylinder have little effect on the fuel droplet gasification process. The droplet size for full evaporation at the end of compression stroke can be estimated using this program.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.459-461
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• 2012

본 논문에서는 식물재배기에 유입되는 조도 정보를 자동 센싱하여 대상 식물의 생육에 적합한 목표조도와 비교과정을 거쳐 LED의 밝기를 지능적으로 제어하기 위한 상황인식기반의 식물재배용 LED 제어 시스템을 구현하고자 한다. 먼저 식물 생육 환경 모니터링을 위해 조도, 온도, 습도, CO2 등의 이기종 센서들을 ZigBee 기반의 통합센서 형태로 설계 및 제작하고, GUI기반의 모니터링 시스템을 구현하여 실시간으로 식물 생육 환경 정보를 수집한다. 데이터베이스에 저장되어 있는 재배대상식물의 표본데이터 중 광보상과 광포화 정보를 기준으로 상황에 따라 변화하는 외부 조도정보와 비교하여 LED 인공광의 밝기를 시스템에 의한 자율 처리에 의해 지능적으로 제어함으로써 불필요한 조명 에너지 소비를 절감하고자 한다.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.10
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• pp.727-732
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• 2004

TCXO is one of the most important component in communication systems. We present a analytic method approach to design the Temperature Compensated Circuit. The conventional method for extracting the circuit parameters, which are for thermistor, Colpitts and frequency control circuit is the trial and error correction. In this paper, we analyse the temperature compensating circuit to extract TCXO circuit parameter. In order to show the validity of this paper, we have designed and implemented the 10MHz TCXO. The fabricated TCXO shows 1ppm frequency drift characteristic over the temperature range of -40℃∼85℃.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.593-594
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• 2008

In this article, process voltage temperature (PVT) compensated on-chip oscillator is implemented by using proportional to absolute temperature (PTAT) circuit and process compensator. Process compensator circuit based on current subtracter and PTAT circuit are proposed for compensation of oscillation frequency to cope with process variation and temperature variation. All circuit can operate in the range of $3.5{\sim}5\;V$ supply voltage. It can be applied to PVT insensitive low frequency clock reference generator.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.193-196
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• 2001

One of the major reasons for not integrating a VCO on one-chip in a PLL (phase locked loop) system is the large chip-to-chip variation of the VCO (voltage controlled oscillator) center frequency. In this thesis, a simple bias technique is proposed to compensate the process fluctuation. The proposed bias technique is applied to the VCO and it reduces the deviation of the VCO center frequency from 35% to 8 %. With the suggested bias technique, a 400 MHz frequency synthesizer is designed for general purpose. It utilizes a programmable divider for various division ratio. The design methodology provides the possibility of the one-chip solution for a PLL system.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1265-1266
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• 2015

본 논문에서는 PMF와 FBG로 구성된 PDL 기반 사냑 간섭계를 이용하여 편광 간섭형 광섬유 압력 센서를 구현하였다. 여러 종류의 PMF들에서 압력 민감도를 비교하기 위해, 서로 다른 세 종류의 보우-타이형 PMF를 센서부로 사용하였다. 구현된 광섬유 압력 센서를 이용하여 0~0.3 MPa의 범위에서 압력 측정을 수행하였으며, 최대 압력 민감도는 근사적으로 -15.07 nm/MPa로 측정되었고, 센서의 선형성을 나타내는 $R^2$값은 ~0.992로 측정되었다. 제안된 센서는 FBG를 이용하여 외부 온도 변화의 보상이 가능하면서도, 이전의 편광유지 광자결정 광섬유 기반 압력 센서에 비해 압력 민감도를 4배까지 증가시킬 수 있었다.

• Journal of Sensor Science and Technology
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• v.18 no.4
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• pp.280-285
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• 2009

In this paper, we designed a 2-stage CMOS operational amplifier with temperature compensation function using 2-poly 4-metal 0.35 $\mu$m standard CMOS technology. Using two bias circuits, the positive temperature coefficient(PTC) and the negative temperature coefficient(NTC) of the bias circuit are canceled out each other. When reference current circuit is simulated that it has a temperature coefficient of -150 ppm/$^{\circ}C$ with a temperature change from 0 $^{\circ}C$ to 120 $^{\circ}C$. Also the proposed circuit has a temperature coefficient of -0.011 dB/$^{\circ}C$ of DC open loop gain with the same temperature range.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1043-1044
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• 2006

본 논문은 전동기의 일정한 공극자속과 전동기에 유입되는 무효전력을 이용한 매트릭스 컨버터 구동장치의 새롭고 간단한 센서리스 기법을 제안한다. 저속의 센서리스 성능 향상을 위해 정류지연, 스위칭장치들의 턴-온, 턴-오프시간 그리고 스위칭장치의 온-상태에서 전압강하와 같은 매트릭스 컨버터의 비선형성을 PQR 전력변환을 이용하여 모델링하고 기준 전류제어기법을 이용하여 보상한다. 3 kW급의 매트릭스 컨버터 구동시스템에 적용하여 제안된 센서리스 기법의 타당성을 검증한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.563-570
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• 1990

A silicon pressure sensor made of a full bridge of diffused resistors was designed and fabricated using semiconductor integrated circuit process. Thin diaphragms with 30\ulcorner thickness were obtained using anisotropic wet chemical etching technique. Our device showed strong temperature dependence. Compensation networks are used to compensate for the temperature dependence of the pressure sensor. The bridge supply voltage having positive temperature coefficient by compensation networks was utilized against the negative temperature coefficient of bridge output voltage. The sensitivity fluctuation of pressure sensor before temperature compensation was -1700 ppm/\ulcorner, while it reduced to -710ppm\ulcorner with temperature compensation. Our result shows that the we could develop accurate and reliable pressure sensor over a wide temperature range(-20\ulcorner~50\ulcorner).

• Journal of Advanced Marine Engineering and Technology
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• v.7 no.1
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• pp.34-39
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• 1983

Development of modern internal combustion engine requires more precise indicator. In the case of strain gage-strain tube type indicator, thermal expansion of the indicator's fixed part makes zero-shift in spite of water cooling. Therefore, the authors analyzed the cause of zero-shift phenomenon on strain gage-strain tube type indicator and proposed a new device to compensate the zero-shift of indicator by electrical method without detoriorating the dynamic charcteristic. As the results, we found that the zero-shift is varied linearlly according to temperature variation of the indicator's fixed part and appling a new device, we can improve the zero-shift of indicator about 0.63% (0.63 kg/$cm^2$) of full scale, though we got 10% of it without the device at the cylinder head operating temperature (c.a. $200^{\circ}C$).