• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.506-512
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• 1997

Ultrasonic knives have been successfully used for the surgery of many medical fields. However, the conventional ultrasonic knives for surgical operation cannot be controlled its resonant frequency. So if the material to cut has different characteristic impedance then different ultrasonic knife will be needed. Because the optimum driving frequency of ultrasonic knife is different by characteristic impedance of material. In this work, using a frequency variable ultrasonic transducer made of multi-layered PZT vibrator, a frequency controllable ultrasonic knife will be suggested. The design and computation principles will be also derived. For this work, firstly, the characteristics of this ultrasonic knife will be analyzed by transmission line model equivalent circuit, and the free admittance characteristics and vibrational velocity distributions will be obtained. Secondly, we will design and make the frequency controllable electrical oscillator for driving this ultrasonic knife.

• Journal of ILASS-Korea
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• v.18 no.3
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• pp.126-131
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• 2013

This paper describes the effect of ultrasonic frequency(f) on the atomization and deformation characteristics of single water droplet in an acoustic levitation field. To achieve this, the ultrasonic levitator that can control sound pressure and velocity amplitude by changing frequency was installed, and visualization of single water droplet was conducted with high resolution ICCD and CCD camera. At the same time, atomization and deformation characteristics of single water droplet was studied in terms of normalized droplet diameter($d/d_0$), droplet diameter(d) variation and droplet volume(V) variation under different ultrasonic frequency(f) conditions. It was revealed that increase of ultrasonic frequency reduces the droplet diameter. Therefore, it is able to levitate with low sound pressure level. It also induces the wide oscillation range, large diameter and volume variation of water droplet. In conclusion, the increase of ultrasonic frequency(f) can enhance the atomization performance of single water droplet.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.63-70
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• 2008

Conical horn is used in many high frequency ultrasonic horns, to achieve a longitudinal vibration mode across a wide ultrasonic tool horn output surface. Modal analysis is method for designing tuned ultrasonic tool horn and for the prediction natural frequency of ultrasonic tool horn vibration mode. The design of ultrasonic horn is based on prototype estimate obtained by FEM analysis. The FEM simulated ultrasonic tool horn is built and characterized experimentally through laser vibrometer and electrical impedance analysis. In this paper, FEM analysis is developed to predict the natural frequency of ultrasonic tool horn and use of in the optimal design of ultrasonic horn shape.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.245-248
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• 1997

The distilled water is used for the ultrasonic wave propagating material in the measurements of broadband ultrasonic attenuation (BUA) that is applied in industrial and medical applications, The acoustic impedance of water is significantly changed with its temperature. Therefore, the quantitative evaluation of BUA with temperature and the ultrasonic wave propagating distance is highly needed. In this study, we evaluated the variation of attenuation with change in temperature. To measure the variation of BUA in the low frequency region at the temperatures, 27$^{\circ}C$, 29$^{\circ}C$, and 31$^{\circ}C$, we tested the Plyethylene, Teflon, MC-Nylon, Urethane specimens and analyzed the center frequency, frequency bandwidth, spectral peak amplitude. The results showed that BUA value appeared to be lower with increasing temperature. This may be due to the fact that the frequency feature of ultrasonic wave is affected by not only the specific gravity, acoustic impedence, but material crystalline, porosity, the distance of ultrasonic wave propagation in water.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_2
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• pp.481-490
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• 2021

In the ultrasonic welding machine, when the load fluctuates, the L and C of the piezo element in the oscillation part change. As a result, the resonant frequency is changed, so it is necessary to match the operating frequency of the ultrasonic welding machine to the new resonant frequency. That is, in order to maximize the output of the oscillation unit of the ultrasonic welding machine, it is inevitable to follow the resonance frequency. Accordingly, many methods for following the resonant frequency are being actively studied. In addition, in order to check the effect of external inductance on the operation of the ultrasonic welding machine, The equivalent circuit of the piezo element was analyzed by including the external inductance for resonance in the equivalent circuit of the piezo element, and the method of selecting an appropriate inductance was described. In this paper, we propose a new system that allows the switching frequency of the inverter to tracking the resonance frequency even if the resonance frequency is changed due to the load of the ultrasonic welding machine.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.1
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• pp.84-91
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• 2013

Ultrasonic flip-chip bonding needs a precise bonding tool which delivers ultrasonic energy into chip bumps effectively to use the selected resonance mode and frequency of the horn structure. The bonding tool is excited at the resonance frequency and the input and output ports should locate at the anti-nodal points of the resonance mode. In this study, we propose new design method with topology optimization for ultrasonic bonding tools. The SIMP(solid isotropic material with penalization) method is used to formulate topology optimization and OC(optimal criteria) algorithm is adopted for the update scheme. MAC(modal assurance criterion) tracking is used for the target frequency and mode. We fabricate two prototypes of ultrasonic tools which are based on 3D optimization models after reviewing 2D and 3D topology optimization results. The prototypes are satisfied with the ultrasonic frequency and vibration amplitude as the ultrasonic bonding tools.

• Journal of Biomedical Engineering Research
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• v.36 no.3
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• pp.69-78
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• 2015

Ultrasonic physiotherapy systems should comply with IEC 60601-2-5(particular requirements for safety of ultrasonic physiotherapy equipment) standard for safety of patients and clinical performances. One of the most important parameters in the standard is the effective radiating area ($A_{ER}$). It has to be measured in accordance with IEC 61689 (field specifications and methods of measurement in the frequency range 0.5MHz to 5MHz). Typical ultrasonic physiotherapy system works in the frequency range 1MHz ~ 3MHz to comply with the IEC 61689. However, ultrasonic physiotherapy system using frequencies over 5MHz is out of the IEC 61689's scope. That is, even if such ultrasonic physiotherapy systems are developed by demands of the market, there is no standard to apply. It is the motivation for this study. Whereas there are other parameters to be considered, this study focuses on the effective radiating area and shows effectiveness of applying IEC 61689 in measuring effective radiating area of ultrasonic physiotherapy systems using frequency range over 5MHz by comparing the results of computer simulation and experiment. Results of this study shows that applying the IEC 61689 standard to ultrasonic physiotherapy system using frequency range over 5MHz is possible.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.4
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• pp.212-216
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• 2005

In an ultrasonic glass scriber, the effect of ultrasonic vibration and its optimum driving frequency were investigated experimentally. To investigate the optimum ultrasonic frequency theoretically, the vibration model of the ultrasonic scriber is assumed. The frequency for maximum amplitude of acceleration is obtained theoretically. To investigate the depth of cutting edge corresponding the each frequency. The quartz glass plate specimen with a dimension of $200mm(L){\times}30mm(W){\times}3mm(T)$ is selected. The ultrasonic transducer is operated by the constant acceleration amplitude for the every frequency. The maximum crack depth was generated when the driving frequency was 18.35kHz. These results were in good agreement with those of the calculated model theoretically.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.395-400
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• 2004

For the purpose of monitoring by ultrasonic test of the ball bearing conditions in rotating machinery, a system for their diagnosis was developed. ultrasonic technique is used to detect abnormal conditions in the bearing system. And various data such as frequency spectrum, energy and amplitude of ultrasonic signals, and ultrasonic parameters were acquired during experiments with the simulated ball bearing system. Based on the above results and practical application for power plant, algorithms and judgement criteria for diagnosis system was established. Bearing diagnosis system is composed of four parts as follows : sensing part for ultrasonic sensor and preamplifier, signal processing part for measuring frequency spectrum, energy and amplitude, interface part for connecting ultrasonic signal to PC using A/D converter, graphic display and software part for display of bearing condition and for managing of diagnosis program.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.696-699
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• 2003

In the semiconductor and the optical industry a new transport system which can replace the conventional sliding system is required. There systems are driven by magnetic field and conveyer belt. The magnetic field damages semiconductor and contact force scratches the optical lens. The ultrasonic wave driven system can solve these problem. In this paper, the object transport system using the excitation of ultrasonic wave is proposed. The experiments for finding the optimal excitation frequency, finding phase-difference between two ultrasonic wave generators are performed. The relationship of transporting speed according to the change of flexural beam shape is verified and the system performance for practical use is evaluated.