• Structural Monitoring and Maintenance
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• v.11 no.3
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• pp.203-217
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• 2024

Electro-mechanical impedance (EMI) technique is a low-cost structural damage detection method. It reflects structural damage through the change in admittance signal which contains the structural mechanical impedance information. The ambient temperature greatly affects the admittance signal, which hides the changes caused by structural damage and reduces the accuracy of damage identification. This study introduces a convolutional neural network to compensate for the temperature effect. The proposed method uses a framework that consists of a feature extraction network and a decoding network, and the original admittance signal with temperature information is used as the input. The output admittance signal is eliminated from the temperature effect, improving damage identification robustness. The admittance data simulated by the finite element model of the spatial grid structure is used to verify the effectiveness of the proposed method. The results show that the proposed method has advantages in identification accuracy compared with the damage index minimization method and the principal component analysis method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.35-42
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• 2004

In this paper, we report Mach Zehnder Interleaver of optical fiber type is fabricated by the fabrication system only for interfermeter design, and it is used $CO_2$ laser to adjust precisely the wavelength. The optical fiber is very sensitive in the thermal variation around. Thus, When fabrication the prototype, it is applied a technique to compensate the optical thermal effect because the center wavelength at the output is shifted according to the thermal variation around. it can he done by applying a substrate with high thermal expansion coefficient as well as an adjusting the position between two optical fiber couplers. Consequently, the output wavelength is shifted within 0.05 nm when the surrounding temperature varies until $60^{\circ}C$.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.254-259
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• 2013

Ball screw system is widely used as a precision mechanical linear actuator that translates rotational motion to linear motion for its high efficiency, great stiffness and long life. Recently, according to the requirements of high accuracy and stiffness, the pre-load on the ball screw which means of remove the backlash in the ball screw is usually used. Because of the preload which means the frictional resistance between the screw and nut, becomes a dominating heat source and it generates thermal deformation of ball screw which is the reason for low accuracy of the positioning decision. There are several methods to solve the problem that includes temperature control, thermal stable design and error compensation. In the past years, researchers focused on the error compensation technique for its ability to correct ball screw error effectively rather than the capabilities of careful machine design and manufacturing. Significant amounts of researches have been done to real-time error compensation. But in this paper, we developed a series of cooling methods to get thermal equilibrium in the ball screw system. So we find the optimum cooling type for improving positioning error which caused by thermal deformation in the ball screw system.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.1
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• pp.48-58
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• 1998

For the purpose of designing novel capacitance pressure sensor, several effects on sensitivity such as parasitic capacitance effects, temperature/thermal drift and leakage current have to be eleiminated. This paper proposed the experimental studies on frequency compensation method by electronic circuit technique, C-V converting method with switched capacitor and C-F converting method with schmitt trigger circuit. The third interface circuit by frequency compensation method is composed to eliminate the drift and leakage component by comparision sensing frequency with reference frequency. The signal transmission is realized by digital signal to minimize the influence of noise and high resolution is obtained by means of increasing the number of digital bits. In the fabricated high performance C-V interface, the offset voltage was not appeared, and in case of voltage source, 4.0V, feed back capacitance, 10㎊, the pressure, 0~10 ㎪, the sensitivity of C-V converter is 28 ㎷/㎪.V, the temperature drift characteristic, 0.051 %F.S./$^{\circ}C$ and C-F converter shows -6.6 Hz/pa, 0.078 %F.S./$^{\circ}C$ respectively, relatively good ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.697-704
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• 2005

In this paper, Passive Temperature Compensation Technology is apply to 8-channel Optical multiplexer with 1000Hz channel spacing. The 8-channel multiplexer is fabricated by connecting three cascaded Mach Zehnder Interferometer(MZI) of optical fiber type, and each interferometer has the wavelength interval of 100GHz, 2000Hz and 4000Hz, respectively. Furthermore, to acquire uniform insertion loss, it is fabricated by using Wavelength Flatten Coupler(WFC) in which the variation of insertion loss is low. $CO_2$ laser to adjust precisely the wavelength. The optical fiber is very sensitive in the thermal variation around. Thus, When fabrication the prototype, it is applied a technique to compensate the optical thermal effect because the center wavelength at the output is shifted according to the thermal variation around. In summary, The prototype composed by eight cascaded MZI has an insertion loss of 5.5 dB, the bandwidth of 0.8nm at 0.5 dB point, and channel crosstalk of 25 dB. Furthermore, the loss dependent on polarization is measured as 0.06dB. Consequently, the output wavelength is shifted within 0.05 m when the surrounding temperature varies until $60^{\circ}C$

• Journal of Sensor Science and Technology
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• v.3 no.2
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• pp.24-32
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• 1994

A force sensor of 30 MN capacity using build-up technique in which three load cells of 10 MN capacity are arranged in parallel was fabricated. A column spring element was adopted as a shape of a strain gage type load cell. Temperature compensation circuits were used to reduce the error of a load cell. It was estimated that the total error of the fabricated force sensor is less than 0.1 %. The force sensor may be used to calibrate or test material testing machines above 4.5 MN capacity in industries.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1218-1223
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• 2007

A surface micro machined angular rate sensor utilizing a vibrating MEMS structure on a silicon has been developed. These tuning fork angular rate sensors are extremely rugged, inherently balanced, and easy to fabricate. The device is fabricated using a temperature compensation method based on automatic gain control technique. A linearity of approximately 0.6%, limited by the on-chip electronics has been obtained with this new sensor. Tests of the sensor demonstrate that its performance is equivalent to that required for implementation of a yaw control system. Vehicle handling and safety are substantially improved using the sensor to implement yaw control.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.47-48
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• 2005

This paper describes how an Artificial Neural Network(ANN) can be employed to improve a speed estimation in a vector controlled induction motor drive. The system uses the ANN to estimate changes in the motor resistance, which enable the sensorless speed control method to work more accurately. Flux Observer is used for speed estimation in this system. Obviously the accuracy of the speed control of motor is dependent upon how well the parameters of the induction machine are known. These parameters vary with the operating conditions of the motor; both stator resistance(Rs) and rotor resistance(Rr) change with temperature, while the stator leakage inductance varies with load. This paper proposes a parameter compensation technique using artificial neural network for accurate speed estimation of induction motor and simulation results confirm the validity of the proposed scheme.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.286-293
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• 2002

Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insolation and temperature occur. A simple method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these Points is presented through deriving small-signal model and transfer function of boost converter. This paper aims at modeling boost converter including equivalent series resistance of input reservoir capacitor by state-space-averaging method and PWM switch model. In the future, properly designed controller for compensation will be constructed in real system for maximum photovoltaic power tracking control.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.60-68
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• 2000

This paper describes a design methodology for the CMOS current source which can be implemented in standard memory process. The proposed techniques provide a good characteristic against the power-supply variation by utilizing a self-bias circuit and the reduction of the first-order component of the temperature variation through the new temperature compensation technique and include a new current-sensing start-up circuit enabling a robust operation against the voltage noise generated during the operation of the chip. In addition to the circuit-design technology, techniques where the proposed CMOS current-reference circuit can be applied to the clocking circuits of a very high-speed DRAM are presented. The feasibility of the suggested design methodology for the CMOS current reference is demonstrated by both the analytical method and the circuit simulation.