• 제어로봇시스템학회논문지
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• 제18권6호
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• pp.546-554
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• 2012

This paper suggests a design method of an improved phase control loop for tracking resonant frequency of solid type precision resonant gyroscope. In general, a low cost MEMS gyroscope adapts the automatic gain control loops by taking a velocity feedback configuration. This control technique for controlling the resonance amplitude shows a stable performance. But in terms of resonant frequency tracking, this technique shows an unreliable performance due to phase errors because the AGC method cannot provide an active phase control capability. For the resonance control loop design of a solid type precision resonant gyroscope, this paper presents a phase domain control loop based on linear PLL (Phase Locked Loop). In particular, phase control loop is exploited using a higher order PLL loop filter by extending the first order active PI (Proportion-Integral) filter. For the verification of the proposed loop design, a hemispherical resonant gyroscope is considered. Numerical simulation result demonstrates that the control loop shows a robust performance against initial resonant frequency gap between resonator and voltage control oscillator. Also it is verified that the designed loop achieves a stable oscillation even under the initial frequency gap condition of about 25 Hz, which amounts to about 1% of the natural frequency of a conventional resonant gyroscope.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.520-523
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• 2004

A phase-locked loop control system designed by using the linear quadratic regulator approach is presented in this paper. The system thus designed is optimal system when system is in locked state and the parameter value of loop filter which is an active PI filter can be obtained easily. By considering the structure of loop filter of phase-locked loop is included in the process to be controlled, a type 1 servo system can be constructed when voltage control oscillator is considered as an integrator. The integral gain of the proposed system obtained by linear quadratic regulator approach can be used as an optimal value to design the parameter of loop filter. The implemented result in controlling the second-order lag pressure process by using the proposed scheme show that the system response is fast with no overshoot and no steady-state error. Furthermore, the experimental results are also shown in term of output disturbance effect rejection, tracking and process parameter changed.

• 대한임상검사과학회지
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• 제44권1호
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• pp.31-37
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• 2012

Many mammals in temperate zones are affected by the distinctive changes of the four seasons in these zones. Their reproductive status is active in the summer climate and inactive during severe winter weather. The golden hamster (Mesocricetus auratus) is seasonal breeding animal whose sexual activities are regulated by photoperoidism. The reproduction and metabolism are activated by long summer days (LD) and inhibited by short winter days (SD). After several months of SD, animals become refractory to this inhibitory photoperiod and spontaneously revert to LD-like physiology. The suprachiasmatic nuclei (SCN) house the primary circadian oscillator in mammals. Seasonal changes in the photic input to this structure control many annual physiological rhythms via SCN-regulated pineal melatonin secretion, which provides an internal endocrine signal representing photoperiod. The aim of this study was to assess the variation in the morphology of the testis in relation to the natural photoperiod in male golden hamsters. The hamsters were castrated at different weeks (2, 5, 8, and 15). The cell numbers of tubules with spermatogonia (SG), spermatocyte (SC), spermatids (ST), and spermatozoa (SZ) were recorded in each sample. The results showed that testicular regression of golden hamsters occurred in the SD-treated animals. The present investigation determines that the effects of the photoperiod on the reproduction of male golden hamsters. It was also found that the circadian period increases the rate of reproductive inhibition in animals exposed to inhibitory photoperiods.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1312-1315
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• 2002

This research describes the design of a fully integrated fractional-N frequency synthesizer intended for the local oscillator in IMT-2000 system using 0.18-$\mu\textrm{m}$ CMOS technology and 1.8-V single power supply. The designed fractional-N synthesizer contains following components. Modified charge pump uses active cascode transistors to achieve the high output impedance. A multi-modulus prescaler has modified ECL-like D flip-flop with additional diode-connected transistors for short transient time and high frequency operation. And phase-frequency detector, integrated passive loop filter, LC-tuned VCO having a tuning range from 1.584 to 2.4 ㎓ at 1.8-V power supply, and higher-order sigma-delta modulator are contained. Finally, designed frequency synthesizer provides 5 ㎒ channel spacing with -122.6 dBc/Hz at 1 ㎒ in the WCDMA band and total output power is 28 mW.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권4호
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• pp.295-301
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• 2008

Recently, the demand on mm-wave (millimeter-wave) applications has increased dramatically. While circuits operating in the mm-wave frequency band have been traditionally implemented in III-V or SiGe technologies, recent advances in Si MOSFET operation speed enabled mm-wave circuits realized in a Si CMOS technology. In this work, a 58 GHz CMOS LC cross-coupled VCO (Voltage Controlled Oscillator) was fabricated in a $0.13-{\mu}m$ Si RF CMOS technology. In the course of the circuit design, active device models were modified for improved accuracy in the mm-wave range and EM (electromagnetic) simulation was heavily employed for passive device performance predicttion and interconnection parasitic extraction. The measured operating frequency ranged from 56.5 to 58.5 GHz with a tuning voltage swept from 0 to 2.3 V. The minimum phase noise of -96 dBc/Hz at 5 MHz offset was achieved. The output power varied around -20 dBm over the measured tuning range. The circuit drew current (including buffer current) of 10 mA from 1.5 V supply voltage. The FOM (Figure-Of-Merit) was estimated to be -165.5 dBc/Hz.

• 한국전자파학회논문지
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• 제22권7호
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• pp.729-736
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• 2011

본 논문은 X-대역에서 바랙터 다이오드가 없는 전압 제어 발진기 구조를 제안하고, 마이크로웨이브 레이더 신호 감지용 수신기에 적용 가능성을 확인하였다. 부성 저항을 발생하는 능동 소자의 콜렉터-베이스 PN-접합으로 바랙터 다이오드를 대체하여, 단일 RF BJT 소자로 전압 제어 발진기를 구현하여 수신기에서 요구하는 튜닝 전압 1.0~7.0 V에서 11.20~11.75 GHz 주파수 가변 특성, 9.0~12.0 dBm 출력 전력 및 선형적인 주파수 튜닝 특성을 만족하였다.

• 한국항만학회지
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• 제14권4호
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• pp.475-479
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• 2000

A possibility of the implementation of a quartz crystal sensor to the determination of chemical oxygen demand is examined by checking the electrochemical behavior of the sensor in a glucose solution. Since the surface of a quartz crystal has to be oxidized, a relatively active metal is coated on the surface of a usual 9 MHz AT-cut crystal. The electrochemical behavior is investigated by measuring the changes of current, resonant frequency and resonant resistance while a constant potential is applied. The crystal is installed in a specially designed container, and a quartz crystal analyzer is utilized to measure the frequency and resistance simultaneously. The variations of the measurements are examined at different concentrations of glucose solution, and a proper relation between the concentrations of glucose solution, and a proper relation between the concentration and the measurements is analyzed. As a result, it is found that a linear relation between the concentration of less than 900 ppm and the peak current when a constant potential of -180 mV (SSCE) is applied. The relation can be utilized for the determination of glucose concentration in sea water, and considering a direct relation between gluose concentration and chemical oxygen demand tells a possibility of the measurement of chemical oxygen demand using quartz crystal oscillators.

• 전자공학회논문지
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• 제50권7호
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• pp.87-95
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• 2013

본 논문에서는 2.5 Gb/s의 입력 데이터율을 가지는 버스트 모드(Burst-mode) 클럭 데이터 복원기(CDR: Clock and Data Recovery)를 제안한다. 제안된 버스트 모드 CDR에서는 입력 데이터율과 클럭 복원기의 개폐 전압제어발진기(GVCO: Gated Voltage Controlled Oscillator) 출력 주파수간의 불일치를 제거하기 위하여 디지털 주파수 보정 기법이 적용되었고, 또한 입력 데이터로 인하여 발생하는 지터(Jitter)를 감소시키기 위하여 지터 제거 기법이 적용되었다. 제안된 버스트 모드 CDR은 0.11 ${\mu}m$ CMOS 공정을 사용하여 설계되었고 루프필터를 제외한 회로 설계 면적은 0.125 $mm^2$이며 전력 소모량은 94.5 mW이다. 포스트 레이아웃 시뮬레이션 결과, 제안된 회로를 통하여 복원된 데이터는 0.1 UI의 입력 지터 인가 시 14 ps의 peak-to-peak 지터를 가지며 최대 허용 CID(Consecutive Identical Digit)는 입력 데이터 지터가 없을 경우 2976 bits를 가진다.

• 전력전자학회논문지
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• 제8권1호
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• pp.70-79
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• 2003

본 연구에서는 압전 변압기를 이용한 T5 28급 전자식 안정기를 제작하여 그에 관한 특성을 조사하였다. 제작된 전자식 안정기는 크게 정류부와 능동형 역률 개선 회로부, 마이크로 컨트롤러를 이용한 주파수 발진부와 피드백 제어 회로부, 그리고 하프-브리지 인버터 회로 및 압전 변압기포 구성하였다. 사용된 원칩 마이크로 컨트롤러(AT90S4433)는 주파수를 발진하는 발진 회로부와 형광램프에 인가된 전류값을 측정하여 램프의 구동여부를 판단하는 피드백 제어 회로부로 구성하였으며, 내부 프로그램에 의해 일정 주파수에서 주파수를 감소시킴으로서 램프 방전을 유도하고 방전을 확인 후 정상상태 구동을 하는 주파수 대포의 이동을 통해 형광램프에 일정한 출력을 유지하였다. 결과적으로 개발된 전자식 안정기는 기존의 자기식 안정기가 무겁고 부피가 크며 많은 손실과 깜박거림(Flicker)현상을 지니는 반면에, 75[kHz]대의 고주파수로 동작하면서 99.5[%]이상의 높은 역률과 12[%]이하의 낮은 총 고조파 왜곡률(THD), 그리고 1.5이하의 CF(Crest Factor)를 나타낸다. 따라서 본 연구에서 제작된 압전형 안정기근 기존의 안정기를 대체할 수 있으며, 소형 경량화 되고 높은 효율을 지니게 되므로 경제적 측면에서의 장점도 기대된다.

• 한국통신학회논문지
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• 제25권4B호
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• pp.613-623
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• 2000

8-VSB(Vestigial Side-Band) 변조 기술을 이용하여 ATSC(Advanced Television Systems Committee) 규격을 만족하는 디지털 TV 튜너를 개발하였다. 이중(double)주파수 변환 및 능동 트래킹 여파기를 튜너 전치단에 이용하여 이미지 응답 및 IF(Intermediate Frequency)Beat 성분들의 억압, 인접 채널과 다채널 수신 시 상호 간섭배제 성능을 만족할 수 있도록 이용하였다. 그러나 NTSC(National Television Systems Committee) 튜너와는 달리, 이중 주파수 변환을 이용하는 디지털 TV 튜너는 트래킹 필터 및 첫 번째 전압제어발진기 사이의 주파수 상관 관계가 존재하지 않는다. 이러한 문제점을 해결하기 위하여 본 논문에서는 마이크로 콘트롤러, EEPROM(Electrically Erasable Programmable Read Only Memory), 디지털/아날로그 변환기, 차동 증폭기 및 스위치 드라이버가 조합된 하드웨어 및 트래킹 전압에 따른 주파수 특성에 대한 주파수 매핑을 구하여 자동 주파수 선택이 가능한 변형된 구조 및 방법을 제시하였다.