• 한국안전학회지
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• 제17권1호
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• pp.39-44
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• 2002

This paper shows error in the polarization direction on ultrasonic transducers how sensitive the shear ultrasonic waves are to a little misoriented plies according to the angle variation of shear ultrasonic waves $0{\circ},\;45{\circ}$ and $90{\circ}$. Also, it is shown that shear waves, particularly the transmission mode with the transmitter and receiver perpendicular to cach other, have high sensitivity for detecting anomalies in fiber orientation and ply layup sequence that may occur in the manufacturing of composite laminates. Experimental results are agreed with a modeling solutions which was based on decomposition of shear wave polarization vector as it propagates through the composite laminates. This wave appeared considerably to be sensitive to CFRP composites to thickness direction along in-plane fibers.

• 조명전기설비학회논문지
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• 제17권6호
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• pp.89-94
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• 2003

최근 에너지의 효율적인 사용을 위해 제작되어 상용화되고 있는 전력변환장치는 기기 특성상 기본파의 n배 주파수를 갖는 고조파를 발생시키고 있다. 이렇게 발생된 고조파는 기본 정현파를 대상으로 제작된 여타 기기의 작동에 악영향을 끼치므로 반드시 제거해야할 요소로 문제시되고 있다. 본 논문에서는 현재 정보화 시대를 맞이하여 증가되고 있는 PC를 대상으로 고조파 발생량을 측정$.$분석 하였으며 그에 따른 가장 효과적인 고조파 저감대책을 제시하였다.

• Journal of Biosystems Engineering
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• 제11권1호
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• pp.24-30
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• 1986

In order to collect the engine performance data accurately, rapidly and reliabily, the microcomputer-based engine performance test system was developed and tested. The system measures engine shaft torque and speed, fuel consumption, exhaust gas temperature, engine shaft power and fuel consumption ratio. The system consisted of 32 channels 8 bit A/D converter, time clock, dynamic strain amplifier and signal conditioning circuits to amplify and filter the electrical signal from transducers. Most of transducers were devised for low cost, easy setting and self-manufacturing. The system has been installed on a small kerosene engine (DAEDONG NA50B).

• The Journal of the Acoustical Society of Korea
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• 제29권3E호
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• pp.111-118
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• 2010

Three-dimensional ultrasound imaging is a new, exciting technology that allows physicians to use ultrasound to view pathology as a volume, thereby enhancing comprehension of patient anatomy. In this paper, a brief history of the 3-D ultrasound imaging is described in accordance with the development of transducer technology. Then, two representative types of 3-D imaging transducers are reviewed with description of the concept and operation principle of each type: mechanical transducer and matrix array transducer. The mechanical transducer is detailed into free-hand scanning and sequential scanning types. Advantages of each transducer over the other and the technical issues for further performance enhancement are also presented.

• Structural Engineering and Mechanics
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• 제4권2호
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• pp.111-124
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• 1996

New active "intelligent" structural systems with integrated self-sensing, diagnosis, and control capabilities can lead to a new design dimension for the next generation high-performance structures and mechanical systems. However, temperature effects to the piezoelectric transducers are not fully understood. This paper is concerned with a mathematical modeling and analysis of a laminated piezothermoelastic cylindrical shell composite exposed to mechanical, electric, and thermal fields. Generic shell equations and solution procedures are derived. Contributions of spatial and time components in the mechanical, electric, and temperature excitations are discussed, and their analytical solutions derived. A laminated cylindrical shell composite with fully distributed piezoelectric layers is used in a case study; its multi-field step and impulse responses are investigated. Analyses suggest that the fully distributed actuators are insensitive to even modes due to load averaging and cancellation. Accordingly, these even modes are filtered from the total response and only the modes that are combinations of m = 1, 3, 5, ${\cdots}$ and n = 1, 3, 5, ${\cdots}$ participating in dynamic response of the shell.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.123-126
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• 2005

The IEEE 1451.4 standards defines an architectural model for interfacing smart transducers for sensors & actuators. This standard allows analogue transducers to communicate their identification and calibration data in a digital format. A digital format is called TEDS(transducer electronic data sheet). However, the standard template of IEEE 1451.4 TEDS do not supports gas sensors to use in electronic nose system, such as array sensors. In this paper, a solution to standardize sensors for electronic nose systems is presented.

• 한국소음진동공학회논문집
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• 제26권7호
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• pp.827-835
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• 2016

Ride comfort of a vehicle is often determined by rubber bushes in suspension system. If transmission forces versus deformations across the bushes are available under operational conditions, improvement of the ride comfort could be done with more ease. Recently, the transmission forces are measured using custom-made force transducers inside the links. This study presents a feasibility study on estimation of the rubber bush deformations using vibration signals on the rigid links. Linear variable displacement transducers as well as piezoelectric accelerometers are used to expand frequency range to very low frequency, which cannot be done with accelerometers only. How to estimate the bush deformation from the two vibration signals on the links are presented together with experimental results.

• 비파괴검사학회지
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• 제31권1호
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• pp.1-10
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• 2011

Nonlinear harmonic waves generated at cracked interfaces are investigated both experimentally and theoretically. A compact tension specimen is fabricated and the amplitude of transmitted wave is analyzed as a function of position along the fatigued crack surface. In order to measure as many nonlinear harmonic components as possible a broadband Lithium Niobate ($LiNbO_3$) transducers are employed together with a calibration technique for making absolute amplitude measurements with fluid-coupled receiving transducers. Cracked interfaces are shown to generate high acoustic nonlinearities which are manifested as harmonies in the power spectrum of the received signal. The first subharmonic (f/2) and the second harmonic (2f) waves are found to be dominant nonlinear components for an incident toneburst signal of frequency f. To explain the observed nonlinear behavior a partially closed crack is modeled by planar half interfaces that can account for crack parameters such as crack opening displacement and crack surface conditions. The simulation results show reasonable agreements with the experimental results.

• 센서학회지
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• 제14권6호
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• pp.444-454
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• 2005

The IEEE 1451.4 standards defines an architectural model for interfacing smart transducers for sensors & actuators. This standard allows analogue transducers to communicate their identification and calibration data in a digital format. A digital format is called the TEDS (transducer electronic data sheet). However, the standard template TEDS of IEEE 1451.4 do not supports sensors to use in electronic tongue system, such as arrayed-potentiometric and voltametric sensors. In this paper, a solution to standardize sensors for E-Tongue (electronic tongue) and electronic tongue systems is presented.

• 센서학회지
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• 제19권2호
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• pp.92-98
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• 2010

The capacitive sensor has a simple structure, compact size and low cost, but a small dynamic range. The small range is caused by use of gap variation. If the sensor takes area variation type with one plate moving horizontally, it can have a large measurable range. While the area variation has relatively low sensitivity, some studies have found methods to improve the sensitivity. Even though the methods are effective, parameters of the results are limited and 2 dimensional. This study provides more practical and 3 dimensional analysis and suggests relations between parameters. Using the results, the optimized design parameters of a high dynamic range capacitive sensor can be found.