• 센서학회지
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• 제31권5호
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• pp.324-329
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• 2022

This paper proposes a shift-register-based multichannel ultrasonic focusing delay control method using a complex programmable logic device (CPLD) for a high resolution of ultrasonic focusing system. The proposed method can achieve the ultrasonic focusing through the delay control of driving signals of each ultrasonic transducer of an ultrasonic array. The delay of the driving signals of all ultrasonic channels can be controlled by setting the shift register in the CPLD. The experiment verified that the frequency of the clock used for the delay control increased, the error of the focusing point decreased, and the diameter of the focusing point decreased as the length of the shift register in the proposed method. The proposed method used only one CPLD for ultrasonic focusing and did not require to use complex hardware circuits. Therefore, the resources required for the design of an ultrasonic focusing system could be reduced. The proposed method can be applied to the fields of human computer interaction (HCI), virtual reality (VR) and augmented reality (AR).

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1046-1050
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• 2003

In this paper, we describe study on the development or multi-path ultrasonic gas flowmeter using a transit time method. This system includes 5 pairs of ultrasonic transducers. ultrasonic signal processing unit using switch matrix method, computation algorithm of gas flow rate, spool piece type multi-path pipe unit. We have developed enhanced type of main ultrasonic signal processing unit using switch matrix method fer multi-path ultrasonic gas flowmeter. Also, we have developed the new transmitting ＆ receiving method of ultrasonic waves and the new signal processing algorithm for the computation of ultrasonic transit time from received ultrasonic waves. In this study, we have designed more compact signal processing unit compared with the conventional hardware system of multi-path ultrasonic gas flowmeter. We have confirmed its reliability for multi-path ultrasonic gas flowmeter through the laboratory test using calibration system. In the future. we will perform the field test for the developed system in the POSCO gas line.

• 제어로봇시스템학회논문지
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• 제13권10호
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• pp.956-961
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• 2007

We propose a new distance measurement method and local positioning system for the autonomous mobile robots localization. The distance measurement method is able to measure long-range distances with a high accuracy by using ultrasonic sensors. The time of flight of the ultrasonic waves include various noises is calculated accurately by the proposed period detecting method. The proposed local positioning system is composed of four ultrasonic transmitters and one ultrasonic receiver. The ultrasonic transmitter and receiver are separated but they are synchronized by RF (Radio frequency) signal. The proposed system using ultrasonic waves is represented as USAT(Ultrasonic Satellite System). USAT is able to estimate the position using the least square estimation. The experimental results show that the proposed local positioning system enables to estimate the absolute position precisely.

• 비파괴검사학회지
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• 제36권2호
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• pp.121-129
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• 2016

As the lifespan of concrete structures increases, their load carrying capacity decreases owing to cyclic loads and long-term effects such as creep and shrinkage. For these reasons, there is a necessity for stress state monitoring of concrete members. Particularly, it is necessary to evaluate the concrete structures for behavioral changes by using a technique that can overcome the measuring limitations of usual ultrasonic nondestructive evaluation methods. This paper proposes the use of a nonlinear ultrasonic method, namely, nonlinear resonant ultrasonic spectroscopy (NRUS) for the measurement of nonlinearity parameters for stress monitoring. An experiment compared the use of NRUS method and a linear ultrasonic method, namely, ultrasonic pulse velocity (UPV) to study the effects of continuously increasing loads and cyclic loads on the nonlinearity parameter. Both NRUS and UPV methods found a similar direct relationship between load level and that parameter. The NRUS method showed a higher sensitivity to micro-structural changes of concrete than UPV method. Thus, the experiment confirms the possibility of using the nonlinear ultrasonic method for stress state monitoring of concrete members.

• 대한가정학회지
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• 제45권10호
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• pp.13-20
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• 2007

A new method for competent extraction of safflower (Carthamus tinctorius Linnaeus) colorants by using ultrasonic device was developed. When comparing to general extraction method, the ultrasonic method showed high extraction efficiency of safflower pigments. Ultrasonic method gave a higher extraction yield of red and yellow safflower pigments than using general method. It is supposed that the extraction efficiency is to be attributed to high vibration energies from ultrasound and finally induced physical changes of the pigments. Furthermore, this study explored the effects of ultrasonic treatment into the extracted safflower pigments on dyeing of cotton fabrics. Ultrasonic treatment into the extracted pigments exhibited significantly improved dyeing properties for the cotton fabrics.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제3B권4호
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• pp.159-164
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• 2003

In this paper, a three-dimensional finite element method and construction of equivalent-circuit for a linear ultrasonic motor are presented. The validity of three-dimensional finite element routine in this paper is experimentally confirmed by analyzing impedance of a piezoelectric transducer. Using this confirmed finite element routine, impedance and vibration mode of a linear ultrasonic motor are calculated. Elliptical motion of contact point between vibrator and rail of the linear ultrasonic motor is shown for determination of contact points. By using the finite element method and analytic equations, characteristics of the linear ultrasonic motor, such as thrust force, speed, losses, powers and efficiency, are calculated. The results are confirmed by experiment. Finally, equivalent circuit parameters of the linear ultrasonic motor are obtained using the three-dimensional finite element method and analytic equations.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.299-302
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• 2002

Characteristics of the twin fluid spray with ultrasonic forcing are examined in order to obtain the high efficiency of cold fog spray of the automatic pest control machine which has been widely used for the equipment cultivation recently. An electrostrictive vibrator of PZT BLT and a magnetostrictive vibrator of ${\pi}type$ with 28 kHz are applied as the ultrasonic transducer. All experiments are made and observed in 4 methods of spray ; a conventional spray method without ultrasonic forcing, an indirect vibration method with ultrasonic forcing, an improving duality method by ultrasonic forced within liquid, and a combined use method with both of the indirect vibration method and the improving quality method. In results, It was clarified that the ultrasonic effects the atomization of spray droplets and its efficiency is about $10{\%}$ and especially much more in the case of the combined use method.

• Journal of Biosystems Engineering
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• 제27권4호
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• pp.317-326
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• 2002

Characteristics of a twin-fluid spray with ultrasonic vibration were examined in order to obtain a high efficiency of cold-fog spray of the automatic pest control machine which has been widely used in protected horticulture recently. An electrostrictive vibrator of PZT BLT and a magnetostrictive $\pi$-type vibrator were used applied as the ultrasonic transducers with a frequency of 28 kHz. All experiments were conducted in 4 methods of spray ; a conventional spray method without ultrasonic forcing, an indirect vibration method with ultrasonic forcing, an improving-quality method by ultrasonic forced within liquid, and a combined-use method with both of the indirect vibration method and the improving quality method. It was found that the ultrasonic energy increased the atomization efficiency of spray droplets about 10% and especially much more in the case of the combined-use method.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1999년도 춘계학술발표회요약집
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• pp.124-124
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• 1999

An ultrasonic method is developed for the measurement of the two-phase mixture level in the reactor vessel or steam generator. The ultrasonic method is selected among the several non¬nuelear two-phase mixture level measurement methods through two steps of selection procedure. A commercial ultrasonic level measurement method is modified for application into the high temperature, pressure, and other conditions. The calculation method of the ultrasonic velocity is modified to consider the medium as the homogeneous mixture of air and steam. and to be applied into the high temperature and pressure conditions. The cross-correlation technique is adopted as a detection method to reduce the effects of the attenuation and the dif.JUsed reflection caused by suface fluctuation. The waveguides are developed to reduce the loss of echo and to remove the effects of obstructs. The present experimental study shows that the developed ultrasonic method measures the two-phase mixture level more accurately than the conventional methods do.

• 제어로봇시스템학회논문지
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• 제14권7호
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• pp.647-655
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• 2008

This paper presents real-time algorithm for an ultrasonic Local Positioning System(LPS). An ultrasonic LPS consists of 4 transmitters and n receivers. Each transmitter transmits an sequential ultrasonic signal to avoid interference of ultrasonic signal. This method is a noneffective application for a fast object. Because receiver detects four sequential transmissive ultrasonic signal and calculates a position. This paper proposes the method which 4 transmitters transmit simultaneous ultrasonic signal and each transmitter distinguished by frequencies and codes. And Auto-Correlation Function(ACF) method separates codes from an ultrasonic echo signal which is interference of each transmitter's code. If the receiver uses only ACF method, it is difficult to implement real time application for increased computation. This paper implements LPS using dual frequencies and ACF method. Using dual frequencies reduces codes length. The reduced codes length save computation in ACF. To prove this algorithm by experiment, high performance DSP(digital signal processor) used. The result shows the performance of the designed system is good enough positioning.