• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.4
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• pp.53-63
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• 2009

This work proposes a 10b 100MS/s 27.2mW $0.8mm^2$ 0.18um CMOS ADC for WLAN such as an IEEE 802.11n standard. The proposed ADC employs a three-stage pipeline architecture and minimizes power consumption and chip area by sharing as many circuits as possible. Two multiplying DACs share a single amplifier without MOS switches connected in series while the shared amplifier does not show a conventional memory effect. All three flash ADCs use only one resistor ladder while the second and third flash ADCs share all pre-amps to further reduce power consumption and chip area. The interpolation circuit employed in the flash ADCs halves the required number of pre-amps and an input-output isolated dynamic latch reduces the increased kickback noise caused by the pre-amp sharing. The prototype ADC implemented in a 0.18um n-well 1P6M CMOS process shows the DNL and INL within 0.83LSB and 1.52LSB at 10b, respectively. The ADC measures an SNDR of 52.1dB and an SFDR of 67.6dB at a sampling rate of 100MS/s. The ADC with an active die area of $0.8mm^2$ consumes 27.2mW at 1.8V and 100MS/s.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.777-780
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• 2005

모바일 오디오 적용을 위한 저전력 ${\Sigma}{\Delta}$ Modulator 에 대한 설계와 layout 을 보였다. 전체 구조는 3 차 단일 피드백 루프이며, 해상도는 16bit 을 갖는다. 샘플링 주파수에 따른 Over-sampling Ratio 는 128(46kHz) 또는 64(96kHz) 가 되도록 하였다. 차동 구조를 사용한 3 차 ${\Sigma}{\Delta}$ modulator 내의 적분기에 사용된 Op-Amp 는 DC-Gain 을 높이기 위해서 Gain-boosting 기법이 적용되었다. ${\Sigma}{\Delta}$ modulator 의 기준 전압은 전류 모드 Band-Gap Reference 회로에서 공급이 되며, PVT(Process, Voltage, Temperature) 변화에 따른 기준 전압의 편차를 보정하기 위하여, binary 3bit 으로 선택하도록 하였다. DAC 에서 사용되는 단위 커패시터의 mismatch 에 의한 성능 감소를 막기 위해, DAC 신호의 경로를 임의적으로 바꿔주는 scrambler 회로를 이용하였다. 4bit Quantizer 내부의 비교기 회로는 고해상도를 갖도록 설계하였고, 16bit thermometer code 에서 4bit binary code 변환시 발생하는 에러를 줄이기 위해 thermometer-to-gray, gray-to-binary 인코딩 방법을 적용하였다. 0.18um CMOS standard logic 공정 내 thick oxide transistor(3.3V supply) 공정을 이용하였다. 입력 전압 범위는 2.2Vp-p,diff. 이며, Typical process, 3.3V supply, 50' C 시뮬레이션 조건에서 2Vpp,diff. 20kHz sine wave 를 입력으로 할 때 SNR 110dB, THD 는 -95dB 이상의 성능을 보였고, 전류 소모는 6.67mA 이다. 또한 전체 layout 크기는 가로 1100um, 세로 840um 이다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1128-1138
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• 2010

One of the typical problems in the precise vibration is resonance characteristics at low frequency disturbance due to a heavy mass. An electro-magnetic(EM) air spring is a kind of vibration control unit and active isolator. The EM air spring in this study aims at removing the low frequency resonance for semiconductor manufacturing. The mechanical and electronic parts in the active isolator are designed to operate under a weight of 2.5 tons. The EM spring is floated using air pressure in a pneumatic elastic chamber and actuated by EM levitation force. The actuator consists of a EM coil and a permanent magnetic plate which are installed inside of the chamber. An air mount was constructed for the experiment with a stone surface plate, 4 active air springs, 4 gap sensors, a DSP controller, and a multi-channel power amp. A PD control method and operating logic was applied to the DSP. Simulation using 1/4 model was carried out and compared with the experiments. The time duration and maximum peak at resonance frequency can be reduced sharply by the proposed system. The results show that the active system can avoid the resonance caused by the natural frequency of the passive system.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.04a
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• pp.161-161
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• 1996

본 연구에서는 차량(승용차) 시동용 수퍼캐패시터-밧데리 조합시스템에 적용할 시작품 전기이중층 수퍼캐패시터(super-capacitor:SC)를 설계 제작 개발하고 그 성능 특성을 확인하였다. 재래식의 차량용 밧데리의 비동력(specific power)이 100~200 W/kg에 비하여 전기이중층 SC의 경우는 1,000~3,000 W/kg으로 단위 총량당의 동력이 매우 크다. 또한 충방전시의 화학반응이 없는 관계로 인하여 충전식 2차 전지에 비하여 사용수명이 매우 길다. 이러한 SC를 기존의 밧데리와 함께 조합하여 차량 시동용으로 사용하게 되면 밧데리의 사용수명을 2~3배 길게 할 수 있으며 밧데리는 시동에 필요한 큰 전류의 방전이 요구되지 않으므로 그 용량과 크기가 대체로 절반이상 줄어든다. 또한 매우 낮은 온도의 기후조건에서는 밧데리의 방전효율이 급격히 저하되므로 이를 대비하여 필요 이상의 과용량, 과중량 밧데리의 사용이 실제로 행해지고 있으나 조합시스템의 차량 시동시에는 SC가 갖는 특성상 -5$0^{\circ}C$까지의 기후조건에서도 방전효율이 크게 저하되지 않은 채 시동전류를 공급해주므로 혹한지역이나 혹한시의 차량시동에도 탁월한 시동성능을 갖는다. 설계 제작된 SC는 저장에너지 6KJ, 정격전압 12Volt, 설계축전용량 70F 그리고 사용은 도 범위가 섭씨 영하 25도에서 영상 50도이며 무공해성 수용성 전해질을 사용하였으며, 제작된 CS는 사용온도 범위에서 축전용량 65F - 85F, 내부저항 1.8mOhm - 5.2mOhm의 변화를 보였으며, 정상시동에 필요한 방전전류 300Amp의 경우 2.6초의 방전시간, 약 89%의 방전효율을 보였다. 현재까지 상온하에서 30.000회의 충방전 시험결과로서는 방전효율의 저하가 없는 양호한 성능을 보였으며, SC의 시범 작동시험을 실차(소나타 1800cc)에 장착하여 수행한 결과 20회 이상의 연속시동에서도 아무런 문제점 없이 잘 동작하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.245-250
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• 2015

We have developed an optical video transmission device for HD-SDI signal transmission. The optical transmitter/receiver unit operates at DC 5 volt and small enough to be attaced near surveillance camera. They have internal voltage regulating circuits to supply 3.3V to other circuits inside the unit. The optical transmitter is composed of cable driver, laser diode driver, and laser diode. The optical receiver is composed of photodiode, limiting amp, and cable equalizer. The wavelength of the trasmitter was 1.3 um, and optical power was -5dBm, and the speed was 1.485Gbps. The receiver sensitivity was -23 dBm. We confirmed that the optical device can transmit HD-SDI video through 30 km optical fiber without any interruption.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.1
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• pp.26-33
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• 1994

A tobacco ripeness grading meter was designed and constructed using the color sensor, its performance was evaluated. A degree of ripeness grading of a leaf is very closely related to the measured tobacco leaf color. Measuring the small amount of the reflectance precisely depends on the apparatus including color sensor, light source, detector sensitivity, and geometric characteristics of appratus. To analyze and minimize the variational effects, experiments to select the proper condition were performed. Because of the combined effect mentioned above, the system has some variation on its response. Basis on the results of the experiments, prototype was developed and interfaced to a computer system. The main components of prototype included a tungsten lamp as a light source, Amorphous full color sensor with three filters, regulated D.C. power supply, OP - AMP(741 TC) for amplification, AR - B3001 board for interfacing to a computer with analog to digital conversion, and a compatible IBM PC XT computer. The experimental results of the developed ripeness tobacco leaf measurement system are summarized as following: [1] The output readings of ripeness grade meter for tobacco leaf, which is based on harvesting time, showed the apparent difference in variety of different quality. It was considered suitable that three filters(red, green, blue) in Amorphous full color sensor could be used in four different ripeness degree measurement of tobacco leaf. [2] The output readings of ripeness grade meter for tobacco leaf, which is based on government procurement, showed apparent difference in variety of different quality. Tobacco leaf varieties to stalk position are divided into tips, leaf, cutters, and primings, It is considered suitable that only red filter in the sensor could be used to classify the grade of tobacco leaf within the same kind tobacco stalk. However, the ripeness grade meter was not adequate to classify all the tobacco grades in the four different tobacco leaves.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.6
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• pp.553-558
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• 2011

This paper describes the development and test result of S-band Transmitter flight model(FM) of STSAT-3 by satellite research center(SaTReC), KAIST. The communication sub-system of STSAT-3 is consist of two different frequency band channels, S-band for Telemetry & Command and X-band for mission data. S-band Transmitter(STX) functionally made of modulator, frequency synthesizer, power amp and DC/DC converter. The transmission data is modulated by FSK(Frequency Shift Keying) and the interface between spacecraft sub-module and STX is RS-422 standard method. The FM STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under $1{\times}10^{-5}$ which meets the specification respectively. The FM STX is delivered Spacecraft Assembly, Integration and Test(AIT) level through the completion of functional Test and environmental(vibration, thermal vacuum) Test successfully.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.7
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• pp.905-917
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• 2021

Atmospheric pollutant emissions, mainly exhaust gas emissions from vessels, and the resultant social costs of pollution in the Korean harbor cities of Incheon, Mokpo, Gwangyang, Busan and Ulsan, are examined in this study, and the need for an emissions reduction plan is highlighted. Busan had several vessels entering its port, while Mokpo had few vessels, yet the vessels emission contribution was high in both the cities. Ulsan had world-class heavy-chemical industries, Gwangyang had steel mills and Incheon had a manufacturing industry and more vessels entering its port than Mokpo, yet the emission contribution was low in these cities. By calculating exhaust gas emissions from the vessels, it was found that CO₂ was the highest, followed by NOx and SOx. By vessel type, Busan, Ulsan, and Incheon had more oil tank vessels, Gwangyang had more cargo vessels, and Mokpo had more ferries. As a result of social cost, Busan paid the highest, while the highest emission was PM. The use of low-sulfur oil can directly reduce PM and, SOx emissions and indirectly reduce NOx emissions. However, in order to reduce high CO₂ emissions, only low-sulfur oil will not help. Therefore, the study suggested the need for reduction plan that use of fossil fuels, by using alternative maritime power (AMP).

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.5
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• pp.25-33
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• 2011

This work proposes a skinny-type 10b 50MS/s 0.13um CMOS three-step pipeline ADC for CIS applications. Analog circuits for CIS applications commonly employ a high supply voltage to acquire a sufficiently acceptable dynamic range, while digital circuits use a low supply voltage to minimize power consumption. The proposed ADC converts analog signals in a wide-swing range to low voltage-based digital data using both of the two supply voltages. An op-amp sharing technique employed in residue amplifiers properly controls currents depending on the amplification mode of each pipeline stage, optimizes the performance of op-amps, and improves the power efficiency. In three FLASH ADCs, the number of input stages are reduced in half by the interpolation technique while each comparator consists of only a latch with low kick-back noise based on pull-down switches to separate the input nodes and output nodes. Reference circuits achieve a required settling time only with on-chip low-power drivers and digital correction logic has two kinds of level shifter depending on signal-voltage levels to be processed. The prototype ADC in a 0.13um CMOS to support 0.35um thick-gate-oxide transistors demonstrates the measured DNL and INL within 0.42LSB and 1.19LSB, respectively. The ADC shows a maximum SNDR of 55.4dB and a maximum SFDR of 68.7dB at 50MS/s, respectively. The ADC with an active die area of 0.53$mm^2$ consumes 15.6mW at 50MS/s with an analog voltage of 2.0V and two digital voltages of 2.8V ($=D_H$) and 1.2V ($=D_L$).

• Annals of Clinical Neurophysiology
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• v.13 no.2
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• pp.80-86
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• 2011

Background: A dry-type electrode is an alternative to the conventional wet-type electrode, because it can be applied without any skin preparation, such as a conductive electrolyte. However, because a dry-type electrode without electrolyte has high electrode-to-skin impedance, an impedance-converting amplifier is typically used to minimize the distortion of the bioelectric signal. In this study, we developed an active dry electroencephalography (EEG) electrode using an impedance converter, and compared its performance with a conventional Ag/AgCl EEG electrode. Methods: We developed an active dry electrode with an impedance converter using a chopper-stabilized operational amplifier. Two electrodes, a conventional Ag/AgCl electrode and our active electrode, were used to acquire EEG signals simultaneously, and the performance was tested in terms of (1) the electrode impedance, (2) raw data quality, and (3) the robustness of any artifacts. Results: The contact impedance of the developed electrode was lower than that of the Ag/AgCl electrode ($0.3{\pm}0.1$ vs. $2.7{\pm}0.7\;k{\Omega}$, respectively). The EEG signal and power spectrum were similar for both electrodes. Additionally, our electrode had a lower 60-Hz component than the Ag/AgCl electrode (16.64 vs. 24.33 dB, respectively). The change in potential of the developed electrode with a physical stimulus was lower than for the Ag/AgCl electrode ($58.7{\pm}30.6$ vs. $81.0{\pm}19.1\;{\mu}V$, respectively), and the difference was close to statistical significance (P=0.07). Conclusions: Our electrode can be used to replace Ag/AgCl electrodes, when EEG recording is emergently required, such as in emergency rooms or in intensive care units.