• 대한기계학회논문집B
• /
• 제35권11호
• /
• pp.1147-1156
• /
• 2011

CLECDiS 는 면적변화형 정전용량 센서의 단점을 극복하고 나노미터 수준의 분해능으로 밀리미터 이상의 큰 변위를 측정하도록 개발된 접촉식 변위센서이다. 그러나 접촉구동 특성으로 인하여 표면평탄도와 마찰에 의해 작은 접촉상태의 변화에도 출력 신호는 크게 왜곡될 수 있어 실제 이를 활용하기 위해서는 전극간 접촉상태를 안정적으로 유지하는 것이 중요하다. 이에 본 연구에서는 전극간 접촉상태의 변화에 따른 신호의 왜곡 특성을 실제 출력 신호와 비교하여 분석하고, 접촉면 내 압력 분포와 센서의 운동 오차 측정을 통해 접촉상태의 변화를 파악하였다. 이를 통하여 센서의 운동 오차와 마찰력의 영향을 최소화하기 위한 접촉 유지 기구를 설계하고 제작하였으며 이를 이용한 구동실험을 통해 보다 안정적인 센서 출력 신호를 획득하였다.

• 한국전기전자재료학회논문지
• /
• 제32권2호
• /
• pp.157-160
• /
• 2019

P(VDF-TrFE-CFE) (Poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene)), which exhibits a high electrostriction of about 7%, can transmit tactile output as vibration or displacement. In this study, we investigated the applicability of P(VDF-TrFE-CFE) to wearable piezoelectric actuators. The P(VDF-TrFE-CFE) layers were deposited through spin-coating, and interspaced with patterned Ag electrodes to fabricate a two-layer $3.5mm{\times}3.5mm$ device. This layered structure was designed and fabricated to increase the output and displacement of the actuator at low driving voltages. In addition, a laser vibrometer and piezoelectric force microscope were used to analyze the device's vibration characteristics over the range of ~200~4,200 Hz. The on-off characteristics were confirmed at a frequency of 40 Hz.

• 한국멀티미디어학회논문지
• /
• 제23권11호
• /
• pp.1372-1382
• /
• 2020

This paper proposes a core technology for a micro river monitoring terminal device suitable for flood monitoring in small rivers and valleys. Our proposed device is basically equipped with a 77GHz radar, gyro and accelerometer sensors. To measure the flow velocity and water level, we proposed a signal processing technique that extracts pure water energy components from the observed Doppler velocity and reflection intensity from the radar. And to determine the stability of the river structure equipped with our device, we constantly monitor the displacement of the measured values of the gyro and accelerometer sensors. Experimental result verified that our method detects pure water energy in various river environments and distinguishes between flow velocity and water level well. And we verified that vibration and position change of structures can be determined through a gyro sensor. In future research, we will work to build a secure digital twin river network by lowering the cost of supplying RF-WAV devices. Also we expect our device to contribute to securing a preventive golden time in rivers.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
• /
• pp.377-379
• /
• 2007

To reduce the chattering errors of reed switch sensors used for automatic remote measurement of water supply system, a reed switch sensor was analyzed and improved. The operation of reed switch sensors can be described as a mechanical contact by approximation of permanent magnet piece to generate an electrical pulse. The reed switch sensors are used in measurement application by detecting the rotational or translational displacement. To apply for flow measurement devices, the reed switch sensors should keep high reliability. They are applied for the electronic digital type of water flow meters. The reed switch sensor is just installed simply on the mechanical type flow meter. A small magnet is attached on a pointer of the water meter counter rotor. Inside the reed sensor, two steel leaf springs make mechanical contact and apart as rotation of flow meter counter. The counting electrical contact pulses can be converted as the water flow amount. The MCU sends the digital flow rate data to the server using the wireless communication network. But it occurs data difference or errors by chattering noise. The reed switch sensor contains chattering error by it self at the force equivalent position. The vibrations such as passing car near to the switch sensor installed location. In order to reduce chattering error, most system uses just software methods for example using filter and also statistical calibration methods. The chattering errors were reduced by changing leaf spring structure using mechanical hysteresis characteristics.

• 한국산학기술학회논문지
• /
• 제20권6호
• /
• pp.439-447
• /
• 2019

본 연구에서는 산사태 축소 모형 장치에 레이저 센서와 진동 센서를 설치하여 강우에 의한 사면 붕괴 시 토사의 미세 변위를 조기에 감지하여 붕괴 위험이 높은 사면에 대한 적절한 대책 마련과 사면 붕괴로 인한 피해를 최소화하기 위한 산사태 발생 시점을 예측하고자 실험을 실시하였다. 또한, 산사태 축소모형 실험을 통해 강우에 의한 토층의 거동 특성 및 간극수압과 수분과 같은 함수비 변화 특성을 분석하였다. 화강암의 풍화토로 인공사면을 조성한 다음 강우 조건을 200mm/hr와 400mm/hr로 달리하여 이에 따른 함수비(수압, 수분) 변화를 측정하고 지표 변위를 분석하기 위해 레이저 센서와 진동 센서를 적용하였으며, 영상분석을 위해 비디오 촬영을 하여 변위 발생시간을 상호 비교 분석하였다. 실험 결과 수분함량은 강우강도가 클수록 한계값 도달시간이 짧게 소요되는 것으로 나타났으며, 간극수압은 강우강도가 클수록 간극수압의 증가 시간이 짧은 것으로 나타났다. 산사태 모형실험은 현장 조건을 충분히 반영하지는 못하지만 진동 센서를 이용한 변위 발생 인지 시간을 측정한 결과 붕괴시점이 레이저 센서를 이용한 방법보다 보다 빠른 것으로 나타났다. 산사태 발생 시 센서를 이용한 지반변위 측정은 지속적인 연구를 수행할 경우 사면붕괴 예측 및 피해 저감 그리고 계측산업 활성화의 기초 자료로 활용이 가능할 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.556-560
• /
• 2005

The measurement method by Laser Speckle Interferometry which uses the interference law which will grow precedes and with it explains a resolution measurement ability and together the change of place arrowhead and general measurement, at real-time measurement sensitivity it has application boat song from candle precise measurement field it is increasing. But, currently the domestic application technique to sleeps and optical science military merit by optical science interferometer and directness it composes purchases to the level which it applies the expensive commercial business equipment the outside and in spite of the technical ripple effect is deficient even in many strong point. The hazard which complements like this problem point form technical development it leads from the research which it sees and an application degree and to sleep as the measurement equipment which tries to develop the small-sized optical science interference sensor and an interpretation program it raises it does.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.199-210
• /
• 2008

Acoustic emission(AE)/Microseimsic(MS) activities are low-energy seismic events associated with a sudden inelastic deformation such as the sudden movement of existing fractures, the generation of new fractures or the propagation of fractures. These events rapidly increase before major failure and happen within a given rock volume and radiate detectable seismic waves. The main difference between AE and MS signals is that the seismic motion frequencies of AE signals are higher than those of MS signals. As the failure of geotechnical structures usually happens as a high velocity and small displacement, it is not easy to determine the precursor and initiation stress level of failure in displacement detection method. To overcome this problem, AE/MS techniques for detection of structure failure and damage have recently adopt in civil engineering. In this study, AE/MS monitoring system, which consist of sensor, data acquisition and operation program, is constructed with domestic technology. To verify and optimize the developed system, we are now carrying out the field application at an underground research laboratory and the developed AE/MS monitoring will be used in detecting of seismic events with various scales.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.792-795
• /
• 2005

The guide-ways of precision machine tools are one of important element of machine tools. It has usually a pair of surfaces for constraint of one direction with bearing. In the case of precision machine tools, non-contact bearing such as hydrostatic bearing and aerostatic bearing is adopted usually. In this case, profiles of rails has effect on straightness and the clearance of bearing has effect on stiffness of guide way, which changes to higher if clearance changes to smaller. The clearance is varied along moving table according to relative distance of pair of rails. The relative distance of pair of rail can be divided by three properties. First and second properties are straightness of each pair of rail and bearing pad. And, third is parallelism about pair of rails and pairs of bearing pad. There are several methods for measuring straightness of each surface such as reversal method, sequential two point method, and way straightness. These straightness measuring methods are always acquiring deviation of profile from eliminating linear fitted inclined line and don't have the information of parallelism. Therefore, to get the small clearance for high stiffness, the straightness of rail and bearing pad and parallelism about pair of rails and pair of bearing pads are measured for correction such as regrinding, reassembling and lapping. In this research, new and easy method for measuring parallelism of pair of rails is suggested. Two displacement probe and sensor stage, which is carry on the displacement sensor, are needed. The simulation and experiment was accomplished about pair of horizontal guide way to confirm the measurement of parallelism. And, the third probe is added to measure the straightness of each rails by sequential two point method. From the estimation of combined these two methods, it is confirmed that the profiles of a pairs of rails can be measured.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.766-777
• /
• 2008

Currently in increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method (NATM). Successful design, construction and maintenance of NATM tunnel demands prediction, control and monitoring of ground displacement and support stress high accuracy. A magnetic anisotropy sensor is used for nondestructive measurement of stress on surfaces of a ferromagnetic material, such as steel. The sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material is measured in a nondestructive manner, which then can be translated into the absolute values of stresses existing on the surface of the material. This technique was applied to measure stresses of H-beams, used as tunnel support structures, to confirm expected measurement accuracy with reading error of about 10 to 20 MPa, which was confirmed by monitoring strains released during cutting tests The results show that this method could be one of the promising technologies for non-destructive stress measurement for safe construction and maintenance of underground rock structures encountered in civil and mining engineering.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 춘계 학술발표회
• /
• pp.1392-1397
• /
• 2010

Currently in increasing number of urban tunnels with small overburden are excavated according to the principle of the New Austrian Tunneling Method(NATM). Successful design, construction and maintenance of NATM tunnel demands prediction, control and monitoring of ground displacement and support stress high accuracy. A magnetic anisotropy sensor is used for non-destructive measurement of stress on surfaces of a ferromagnetic material, such as steel. The sensor is built on the principle of the magneto-strictive effect in which changes in magnetic permeability due to deformation of a ferromagnetic material is measured in a non-destructive manner, which then can be translated into the absolute values of stresses existing on the surface of the material. This technique was applied to measure stresses of H-beams, used as tunnel support structures, to confirm expected measurement accuracy with reading error of about 10 to 20MPa, which was confirmed by monitoring strains released during cutting tests The results show that this method could be one of the promising technologies for non-destructive stress measurement for safe construction and maintenance of underground rock structures encountered in civil and mining engineering.