• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.245-246
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• 2009

정전용량형 후막 스트레인 게이지(piezocapacitive thick film strain gage)는 세라믹 ($Al_2O_3$)을 주 원료로 하는 지지대(약 5mm)와 다이어프램(약 $300{\mu}m$) 그리고 가드 링으로 구성된다. 전극 판은 도전성 페이스트를 이용하여 지지대와 다이어프램에 형성되었으며 극판 사이에는 유전체 메이스트를 사용하여 스크린 인쇄로 후막을 형성하였다. 극판 사이의 가드 링 두께는 약 $30{\mu}m$정도로 다이어프램의 변위 최대값을 유지시키는 데 필요한 간격이다. 따라서 정전용랑형 후막 스트레인 게이지는 지지대를 중심으로 다이어프램에 압력 (0.5~1.0bar)이 인가될 때 변위를 발생시키면서 커패시터 값이 압력의 크기에 따라 비례 특성을 가지고 변화하는 것을 이용한 것이다. 압력이 없을때 초기값은 35pF~40pF 정도이고 정격압력의 최대치를 인가시켰을 때 약 55pF~55p를 나타내었다.

• Journal of the Korean Institute of Gas
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• v.7 no.3 s.20
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• pp.13-17
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• 2003

A membrane unit for Liquefied Natural Gas (LNG) storage tank is a structural member which is designed specifically for preventing undesirable LNG leakage. Membrane units have to endure gas and liquid pressures by LNG and thermal stresses by the contact with cryogenic liquid of $-162^{\circ}C$. It is of importance to assure the strengths of membrane by experimental stress analysis under the temperature of LNG. In this paper, we proposed measurement system using commercial electrical strain gage and mechanical extension meter designed for this study.

• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.163-170
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• 2000

Optical frequency modulated fiber optic interferometric sensor was developed to sense the mechanical quantities, such as displacement, strain, force etc. It has been difficult to distinguish whether the increase of the mechanical quantities or the decrease of the quantities measured by the conventional fiber optic interferometric sensors because their signals only have a sinusoidal wave pattern related to the change of mechanical quantities. In this study, in order to measure the mechanical quantifies with the distinction of the changing direction of the quantities, the fiber of optic Michelson interferometric sensor was simply constructed by the laser light modulated with saw tooth wave pattern. The output signal of the sensor was controlled as the sinusoidal wave. The signal processing was based on the counting of the wave number of the output signal during constant time duration. The strain was determined by the cumulative value of the wave number producted by the gage factor. In order to verify the strain measurement capability of this sensor, the strain increase-decrease test was performed by universal testing machine installed with the aluminum specimen bonded with the fiber optic sensor and electrical strain gage. In the result of the test, the strain from the fiber optic sensor had a good agreement with the values from the electrical strain gage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.107-109
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• 2003

The magnetostriction of FeCoGe/phenol composites is measured under the external magnetic field. A few Measurement are carried out by using the electrical-resistance strain gage, the Wheaton Bridge for eliminating the unnecessary voltage, the lock-in-amplifier for the signal amplification and noise filtering. When the external magnetic field is applied to the longitudinal direction against those samples which is the 10wt.% phenol in composites, the theoretical maximum strain of 120ppm is obtained. According to the larger strain than that of others solid state actuators and piezoelectric actuators. FeCoGe/phenol composites could be useful as an actuator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.325-328
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• 2003

The magnetostriction of FeCoGeW/phenol composites is measured under the external magnetic field. A few Measurement are carried out by using the electrical-resistance strain gage, the Wheaton Bridge for eliminating the unnecessary voltage, the lock-in-amplifier for the signal amplification and noise filtering. When the external magnetic field is applied to the longitudinal direction against those samples which is the 10wt.% phenol in composites, the theoretical maximum strain of 120ppm is obtained. According to the larger strain than that of others solid state actuators and piezoelectric actuators. FeCoGeW/phenol composites could be useful as an actuator.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1416-1418
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• 1994

Expressions for the displacement of a bimorph, one end fixed and the other free, has been introduced when sinusoidal inputs were applied to the ceramic plates on a thin metal plate. Maximum displacements at the free end and strains at the position of strain gage attached were measured when various wave forms, voltages, and frequencies were applied to the bimorph whose length is 6.6[cm], width 2.5[cm], and thickness 0.0365[cm]. Under the constant voltage ( $70[V_{peak}]$ ), the strains and the displacements at the free end were larger than the case of the sinusoidal input when the square wave was applied and were smaller when triangular wave. It was shown that the displacements at the free end and the strains of the gage position were increased as the applied voltage in the range of $30-90[V_{peak}]$ and effective length were increased. And it was also found that the resonant frequency of a bimorph was decreased as its effective length was increased, and that the displacements and the strains were maximum at the resonant frequency.

• 한국가스학회:학술대회논문집
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• 2003.10a
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• pp.85-90
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• 2003

Korea Gas Corp. has developed the design technology of the LNG storage tank. The membrane to be applied inside of LNG storage tank is provided with corrugations to absorb thermal contraction and expansion caused by LNG temperature. We constructed strain measurement system by using strain gage. In this paper, some problems which should be considered when measuring strain at $-162^{\circ}C$, are discussed by presenting test results on the characteristics of strain gages, Temperature sensor, adhesive and lead wire. And presenting the procedure of the constructing strain measurement system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.577-580
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• 2003

The magnetostriction of FeCoGe/phenol composites, which is one of the magnetostrictive materials, measured at the external magnetic field. The measurement was carried out using the electrical-resistance strain gage, the wheaten's Bridge for eliminating the unnecessary voltage, and the lock-in-amp for signal amplification and noise filtering. When the external magnetic field was applied in the longitudinal the samples, the maximum strain of 120ppm was taken with regard to the 10wt.% phenol composite. This results indicate that the FeCoGe/phenol composites can be useful as an actuator because it has larger stain than the other solid state actuators such as piezo electric materials.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.31-34
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• 2002

A study on the method that can measure the internal strain of composite materials is performed to monitor the health status of composite structures. A fiber optic sensor was constructed using the total reflected extrinsic Fabry-Perot interferometer(TR-EFPI) probe with a broadband light source. Result obtained from electrical strain gage adhered on the aluminum beam specimen was compared with that from the fiber optic TR-EFPI sensor and showed a good agreement. It was found that fiber optic TR-EFPI sensor system was adequate for monitoring the strain and thus failure processes in the interior of composite materials.

• Smart Structures and Systems
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• v.18 no.6
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• pp.1217-1231
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• 2016

In this research, a slotted patch antenna sensor is designed for wireless strain and crack sensing. An off-the-shelf RFID (radiofrequency identification) chip is adopted in the antenna sensor design for signal modulation. The operation power of the RFID chip is captured from wireless reader interrogation signal, so the sensor operation is completely battery-free (passive) and wireless. For strain and crack sensing of a structure, the antenna sensor is bonded on the structure surface like a regular strain gage. Since the antenna resonance frequency is directly related with antenna dimension, which deforms when strain occurs on the structural surface, the deformation/strain can be correlated with antenna resonance frequency shift measured by an RFID reader. The slotted patch antenna sensor performance is first evaluated through mechanics-electromagnetics coupled simulation. Extensive experiments are then conducted to validate the antenna sensor performance, including tensile and compressive strain sensing, wireless interrogation range, and fatigue crack sensing.