• 전자공학회논문지
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• 제52권8호
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• pp.29-39
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• 2015

본 논문은 모바일 광학식 손떨림 보정(OIS) 움직임 검출부의 성능과 안정도를 높이기 위하여 퍼지기반 손떨림 상태 검출 및 오차 보상 알고리즘의 설계 및 구현을 기술한다. OIS 움직임 검출을 위한 자이로 센서 출력에는 소자의 고유 오차가 포함되어 있기 때문에 신속한 손떨림 보정과 안정적인 손떨림 상태 검출을 위해서 정확한 오차 보상이 요구된다. 본 연구에서는 퍼지 알고리즘을 기반으로 낮은 연산량을 통해서 손떨림 주파수에 대한 각도 및 위상 오차를 신속하게 줄여서 보정 성능을 개선하였다. 또한 손떨림 각도 크기에 따라 {정지, 작은 손떨림, 큰 손떨림, 팬/틸트} 등의 손떨림 상태를 적절히 구분해서 시스템의 안정성을 향상시켰다. 모바일 OIS 움직임 검출부를 위해 제안된 알고리즘의 성능 및 안정도를 실제 손떨림과 같은 2~12Hz 주파수 범위의 ${\pm}0.5^{\circ}$, ${\pm}0.8^{\circ}$ 손떨림 진동에 대해서 정량적 및 정성적 실험으로써 평가하였다. 실험결과를 통해서 기존 BACF/DCF 알고리즘과 비교해서 평균 3.71dB의 개선된 성능을 검증하였고, 4가지 손떨림 상태를 안정적으로 검출하는 동작을 확인하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 추계학술대회
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• pp.39-42
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• 2018

본 논문에서는 진동 에너지 수확을 위한 MPPT 제어기능을 갖는 인터페이스 회로를 설계하였다. 설계된 회로는 수확된 교류 형태의 에너지를 시스템 구동에 필요한 직류 형태의 에너지로 정류하고, MPPT Controller를 통해 Open Circuit Voltage(Voc)를 주기적으로 샘플/홀드한 뒤, 입력전압을 최대 가용 전력점의 1/2되는 전압으로 유지시키면서, 수확된 전력을 부하에 전달하는 동작을 한다. 모든 회로들은 0.35-um CMOS 기술을 기반으로 설계되었으며, 모의실험을 통하여 동작을 검증하였다. 모의실험 결과 설계된 회로는 3V 입력전압에서 98nA의 전류를 소모하며, 최대 전력효율은 99.21%이다. 설계된 회로의 칩 면적은 $1.281mm{\times}1.236mm$ 이다.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.197-201
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• 2002

A free piston and free displacer (FPFD) Stirling cryocooler and inertance pulse tube cryocooler for the cooling infrared detector and cryosensor are currently under development at Korea Institute of Machinery ＆ Materials. The pulse tube cryocooler, which has no moving parts at its cold section, is attractive for obtaining higher reliability, simpler construction and lower vibration than in any other small cryocoolers. In recent years, pulse tube cryocoolers have experienced a rapid development with the aim to eventually replace Stirling and Gifford-McMahon cryocoolers in various applications. In this study, operating characteristics of the conventional linear Stirling cryocooler was investigated by experiment. And, inertance pulse tube cryocooler with the commercial linear compressor(Leybold Polar) was designed, manufactured, and tested by the variations of the operating frequency, charging pressure and input power.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.415-419
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• 2000

Multi-degree-of-freedom (MDOF) displacement measurement Is needed In many application fields: precision machine control, precision assembly, vibration analysis, and so on. This paper presents a new MDOF displacement measurement method using a laser diode (LD), two position-sensitive detectors (PSDs), and a conventional diffraction grating. It utilizes typical features of a diffraction grating to obtain the information of MDOF displacement. MDOF displacement is calculated from the independent coordinate values of the diffracted ray spots on the PSDs. Forward and inverse kinematic problems were solved to compute the MDOF displacement of a rigid body. Experimental results show maximum absolute errors of less than ${\pm}10$ micrometers in translation and ${\pm}30$ arcsecs in rotation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1867-1870
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• 1997

A Laser Doppler Vibrometer (LDV) based on the heterodyne method was developed using He-Ne laser as a light source. The heterodyne method was employed to eliminate the ambiguity in the direction of the motion. The frequency shifted object beam (40 MHz) by a Bragg cell was focused on the surface of the moving target and the Doppler shifted reflected beam was combined at the fast photodetector to produce frequency modulated signal centered at 40 MHz. The signal from the detector was amplified, filtered and downconverted to intermediate frequency centered at 5 MHz. The voltage output that was proportional to the velocity of the moving surface was obtained using PLL. This LDV can be used to measure the resonant frequency of the electric equipments such as circuit breakers and bushings, of which resonant frequencies are changed when they are damaged.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.519-526
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• 2003

In this paper, a Fiber Bragg Grating (FRG) sensor system is described and FBGs are well-suited for long term and extremely severe experiments, where traditional strain gauges fail. In the system, a reflect wave-length measurement method which employs a tunable light source to find out the center wave-length of FBG sensor is used. We apply the FBG system to nuclear energy Power Plant for structural integrity test to measure the displacement of the structure under designed pressure and to check the elasticity of the structure by measuring the residual strain. The system works very well and it is expected that it can be used for a real-time strain. temperature and vibration detector of smart structure.

• 센서학회지
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• 제24권2호
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• pp.93-95
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• 2015

We present an optical detection method for the fundamental vibrational mode of a tuning fork crystal oscillator in air. A focused He/Ne laser beam is directed onto the edge of one vibrating tine of the tuning fork; its vibrating motion chops the incoming laser beam and modulates the intensity. The beam with modulated intensity is then detected and converted to an electrical signal by a high-speed photo-detector. This electrical signal is a sinusoid at the resonant frequency of the tuning fork vibration, which is 32.76 kHz. Our scheme is robust enough that the sinusoidal signal is detectable at up to $40^{\circ}$ of rotation of the tuning fork.

• 대한의용생체공학회:의공학회지
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• 제25권5호
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• pp.343-349
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• 2004

전기성문전도는 발성시에 성문의 진동이 전기적 임피던스를 이용하여 검출되는 신호이다. 본 연구는 이러한 전기성문전도를 기록하기 위한 장비를 구현하고 음성분석 및 후두질환 진단에 대한 적용생을 평가하고자 하였다. 전기성문전도의 하드웨어는 2 쌍의 링전극, 동조증폭기, 검파기, 저역통과필터, 자동이득조절부 등으로 구성되며, 2.7MHz의 반송파 신호를 이용하고 진폭 변조 방식의 검파를 통해 임피던스 신호를 추출하도록 하였다. 추출된 신호는 PC 사운드 카드의 라인 입력을 통해 샘플링되고 양자화되었다. 검출 신호를 분석하기 위한 파라미터는 패래 시간을(CQ), 개폐 속도율(SQ), 개폐속도지수(SI), 성대진동 주파수(F0), 성대진동 주파수변동지수(Jitter), 성대진동 진폭변동지수(Shimmer) 등을 추출하였다. 전기성문전도를 분석한 결과, F0가 증가할수록 CQ는 커지고, SQ와 SI는 작아지는 경향을 보였으며, 전기성문전도와 음성 선호의 기본주파수가 일치함을 알 수 있었다. CQ, SQ, SI는 정상인과 후두암 환자를 비교한 결과 유의한 차이를 보였다. 이러한 결과는 성대의 운동을 관찰할 수 있는 휴대용 전기성문전도 계측기의 구현이 가능하게 하였고, 성대 기능 이상 검사가 가능함을 시사하였다.

• 한국안전학회지
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• 제27권3호
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• pp.36-41
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• 2012

Electrical Connections often cause fires due to poor contact. Occurrence rate of these fires tends to increase annually. The reason why poor contacts occur is often because it is the low mechanical pressure at the contact points. A typical connection method using mechanical pressure is a screw terminal type. This study reviewed these poor contact cases in the screw terminals. In order to get reproduction of such cases, two types of experiments were conducted. the first one was conducted under the normal contact condition, and the other one was conducted under the poor contact condition that screw terminal of breaker was loosen and did not meet the requirements of toque value. In both types of experiments, compulsory vibration was adopted as a variable to aggravate poor contacts. Each of various current values(4.5A, 9.0A, 13.5A) is input. In these experiments, relationships of a contact, electrical signal such as current and electric pulse by ZCT and thermal characteristics according to vibration effect are analyzed. The suggested data and results in this study provide the useful resources helping to investigate fires due to poor contact, and they develop the detector for poor contact and finally reduce the electrical fire occurrence rate.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제27회 춘계학술대회
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• pp.321-327
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• 1998

This paper presented a case study on the application of on-line wear monitoring technique to a high duty air-turbo-compressor system. Main objects monitored were a gear unit and metal bearings, both shown frequent troubles due to the severe operation conditions at heavy dynamic load. The air-turbo-compressor system needs secure condition monitoring because it is one of the main utilities in steel making industry. Temperature and vibration characteristics have been mainly on-line monitored in this system for a predictive maintenance; however, it has been shown that they are not fairly good enough to give an early warning prior to the machine failure. In this work, an on-line Opto Magnetic Detector(OMD) was implemented for an on-line wear monitoring, which quantitatively measured the contamination level of both ferrous and non-ferrous wear particles by detecting the change in optical density of used oil. Results showed that the application of on-line OMD system was satisfactory in diagnosis of the machine system.