• Journal of Biosystems Engineering
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• 제28권3호
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• pp.239-244
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• 2003

The potential use of ultrasonic technique for firmness measurement of apples was evaluated. Mechanical properties(bioyield deformation, bioyield strength, rupture deformation, ultimate strength, and elastic modulus) and ultrasonic parameters (ultrasonic velocity, attenuation coefficient and the first peak frequency) of the apple flesh during the storage time were measured and analyzed. Ultrasonic parameters were determined from the measurement of ultrasonic wave transmission through the apple flesh specimen. Mechanical properties were obtained by universal testing machine. The bioyield strength, rupture strength, elastic modulus, ultrasonic velocity, and the first peak frequency of the apple flesh decreased with the storage time. The bioyield deformation, rupture deformation, and ultrasonic attenuation coefficient increased with the storage time. The correlation analysis between ultrasonic parameters and mechanical properties and the storage time was performed. The high correlations were found between the storage time and the ultrasonic parameters, and these relationships seem to be useful for determining the firmness of the apple flesh.

• 한국축산식품학회지
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• 제21권2호
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• pp.126-132
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• 2001

This study was carried out to investigate the effect of ultrasonic treatment on physicochemical and sensory properties of cooked chicken meat. Moisture content of ultrasonic treated breast meat was higher than that of control, fat content of control of breast and leg meat were higher than that of ultrasonic treatment, and protein of control of breast meat was higher than that of ultrasonic treatment. Hunters L(lightness)-and a(redness)-value were not different between cooking methods, L-value of breast meat and a-value of leg meat were higher without regard to cooking method. Hunterb (yellowness)-value was not different among cooking chicken meats. Cooking yield was not different between cooking methods, pH of ultrasonic treated chicken meats were higher than that of control. Water holding capacity and salt soluble protein extractability of ultrasonic treated breast meat were greater than that of control. Water soluble protein extractability of ultrasonic treated leg meat was higher than that of control, and shear force value was not different between cooking methods. Hardness, cohesiveness and gumminess were not different between cooking methods and parts of muscle. Springiness of ultrasonic treated leg meat was greater than that of control and chewiness of breast meat was higher than that of leg meat. Aroma, texture, juiciness and overall acceptability were not different between cooking methods, taste of ultrasonic treated leg meat was higher than that of control. In addition, the sensory scores of parts of muscle were affected greater than that of cooking methods.

• Journal of Biosystems Engineering
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• 제38권3호
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• pp.192-198
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• 2013

Purpose: Methods for non-destructive estimation of product quality have been reported in various industrial fields, but the application of ultrasonic techniques for the agricultural products of potatoes, pears, apples, watermelons, kiwis and tomatoes etc. have been rarely reported since the application of a contact-type ultrasonic transducer in agricultural products is very difficult. Therefore, this study sought to determine the firmness of apples using non-contact ultrasonic techniques. Methods: For this experiment, an ultrasonic experimental tester using a non-contact ultrasonic transducer was created, and a signal processing program was used to analyze the acquired ultrasonic reflected signal. Also, a universal testing machine was used to measure firmness parameters of the apples such as bioyield strength, a firmness factor, after the ultrasonic tests had been performed. Results: Six distance correction factors were calculated to obtain consistent values of ultrasonic properties regardless of the distance between the transducer and the surface of the subject. We developed prediction models of the bioyield strength using the distance correction factors. Conclusions: The optimum prediction model of the bioyield strength of apples using a non-contact ultrasonic technique was a multiple regression model ($R^2=0.9402$).

• Smart Structures and Systems
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• 제25권3호
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• pp.301-310
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• 2020

The laser ultrasonic technique is gaining popularity for nondestructive evaluation (NDE) applications because it is a noncontact and couplant-free method and can inspect a target from a remote distance. For the conventional laser ultrasonic techniques, a pulsed laser is often used to generate broadband ultrasonic waves in a target structure. However, for crack detection using nonlinear ultrasonic modulation, it is necessary to generate narrowband ultrasonic waves. In this study, a pulsed laser is shaped into dual-line arrays using a spatial mask and used to simultaneously excite narrowband ultrasonic waves in the target structure at two distinct frequencies. Nonlinear ultrasonic modulation will occur between the two input frequencies when they encounter a fatigue crack existing in the target structure. Then, a nonlinear damage index (DI) is defined as a function of the magnitude of the modulation components and computed over the target structure by taking advantage of laser scanning. Finally, the fatigue crack is detected and localized by visualizing the nonlinear DI over the target structure. Numerical simulations and experimental tests are performed to examine the possibility of generating narrowband ultrasonic waves using the spatial mask. The performance of the proposed fatigue crack localization technique is validated by conducting an experiment with aluminum plates containing real fatigue cracks.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.1846-1857
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• 2021

Ultrasonic nondestructive testing is important for monitoring the structural integrity of dissimilar metal welds (DMWs) in pressure vessels and piping in nuclear power plants. However, there is a low probability of crack detection via inspection of DMWs using ultrasonic waves because the grain structures (grain orientations) of the weld area cause distortion and splitting of ultrasonic beams propagating in anisotropic media. To overcome this issue, the grain orientation should be known, and a precise ultrasonic wave simulation technique in anisotropic media is required to model the distortion and splitting of the waves accurately. In this study, a method for nondestructive prediction of the DMW grain orientations is presented for accurate simulation of ultrasonic wave propagation behavior in the weld area. The ultrasonic wave propagation behavior in anisotropic media is simulated via finite-element analysis when ultrasonic waves propagate in a transversely isotropic material. In addition, a methodology to predict the DMW grain orientation is proposed that employs a simulation technique for ultrasonic wave propagation behavior calculation and an optimization technique. The simulated ultrasonic wave behaviors with the grain orientations predicted via the proposed method demonstrate its usefulness. Moreover, the method can be used to determine the focal law in DMWs.

• 물과 미래
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• 제26권1호
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• pp.63-69
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• 1993

매립이 완료된 Landfills이나 오염된 지하수의 오염물질을 제거하여 다른 용도로 재사용하는 기술이 오늘날 중요한 문제로 대두되고 있다. 진동을 이용하여 제가효율을 높히는 방법은 요즘 흔히 사용되고 있는 방법중의 하나이다. Ultrasonic의 효과를 사용함으로써, 기계적인 제거효과가 대단하다는 것은 이미 몇몇 연구자들에 의해 확인된바 있다. 이 연구에서는 Probe-Type Lutrasonic Processor를 사용하여 Clayey-Sand Chamber를 가지고 실험을 해보았다. 실험중 계속적인 Pumping과 함께 Ultrasonic을 작동시킨 결과, Clayey 입자들의 분리 및 제거에 큰 효과를 얻었으며, 그로 인하여 투수계수가 크게 증가하는 효과를 보았다. 또한, 실험 전과 후의 입자크기의 분포도가 크게 변했는데, 그 이유는 Ultrasonic의 진동효과 때문이다. 실험결과, 0.004mm 이하의 입자들은 Ultrasonic의 효과에 의해 Mobilize되었으며, 0.04-1.0mm의 입자는 부서져서 작은 입자로 되었다. 이 기구를 사용하기 위한 유지비와 전력비등을 고려하여 이 기구의 실용성을 검토해 보았다. 필요한 Power를 위해 요구되는 전력의 양은 깊이에 의한 대상 site의 응력, 온도, 그리고 Fuid의 Viscosity에 의해 좌우되며, 그중 가장 큰 영향을 미치는 요소는 흙의 깊이이다. 여러 가지의 다른 깊이에서의 경제적인 실용성을 1.0, 2.0in 직경의 Horn Sonicator를 사용했을 경우에 대하여 비교와 분석을 하였다.

• 비파괴검사학회지
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• 제19권5호
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• pp.363-368
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• 1999

시험체의 두께나 초음파 속도를 측정하기 위해서 초음파 펄스-에코법이 널리 사용되고 있다. 초음파 속도를 결정하기 위해서는 초음파 송수신 장치를 포함한 오실로스코우프와 같은 초음파 측정 장치를 사용하여 시험편에서의 초음파진행 시간을 측정하고, 초음파 진행 거리에 해당하는 시험편의 두께를 버어니어 캘리퍼스 또는 마이크로미터와 같은 길이측정 도구를 사용하여 측정한다. 그리고 초음파를 이용하여 시험편의 두께를 측정할 때에는 초음파 속도를 알고 있는 대비 시험편으로 기준을 설정하여야 한다. 본 연구에서는, 대비 시험편 없이 재료의 두께와 초음파 속도를 동시에 구하는 방법을 제시하였다. 재질과 두께를 달리한 여러 시험편에서 측정된 초음파 속도와 두께가 기존의 방법에 의해 측정한 값과 잘 일치하였다.

• 한국정밀공학회지
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• 제30권11호
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• pp.1121-1128
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• 2013

Ultrasonic grinding system is that the ultrasonic vibration by ultrasonic actuator is applied on conventional grinding system during grinding process. The Ultrasonic vibration with a frequency of over 20kHz can reduce grinding forces and increase surface quality, material removal rate (MRR) and grinding wheel life. In addition, ultrasonic vibration assisted grinding can be used for the materials that are difficult to cut. In this paper, methodology for ultrasonic tools is studied based on finite element method, and in turn the ultrasonic tools are designed and fabricated. It is found that the ultrasonic tool can vibrate with a frequency of 20kHz and amplitude of $25{\mu}m$. In order to verify the machining performance, the grinding experiment is performed on titanium alloy. By applying ultrasonic vibration, the grinding force and temperature are reduced and MRR is increased compared with the conventional grinding.

• 한국소음진동공학회논문집
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• 제20권11호
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• pp.1078-1088
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• 2010

In order to analyze the quantitative characteristics of acoustic streaming, experimental setup of 3-D stereoscopic PIV(particle imaging velocimetry) was designed and quantitative ultrasonic flow fields in the gap between the ultrasonic vibrator and heat source were measured. Utilizing acoustic streaming induced by ultrasonic vibration, surface temperature drop of cooling object was also measured. The study on smart cooling method by acoustic streaming induced by ultrasonic vibration was performed due to the empirical relations of flow pattern, average flow velocity, different gaps, and enhancement on cooling rates in the gap. Average velocity fields and maximum acoustic streaming velocity in the open gap between the stationary cylindrical heat source and ultrasonic vibrator were experimentally measured at no vibration, resonance, and non-resonance. It was clearly observed that the enhancement of cooling rates existed owing to the acoustic air flow in the gap at resonance and non-resonance induced by ultrasonic vibration. The ultrasonic wave propagating into air in the gap creates steady-state secondary eddy called acoustic streaming which enhances heat transfer from the heat source to encompassing air. The intensity of the acoustic streaming induced by ultrasonic vibration experimentally depended upon the gap between the heat source and ultrasonic vibrator. The ultrasonic vibration at resonance caused the increase of the acoustic streaming velocity and convective heat transfer augmentation when the flow fields by 3D stereoscopic PIV and temperature drop of the heat source were measured experimentally. The acoustic streaming velocity of air enhancement on cooling rates in the gap is maximal when the gap agrees with the multiples of half wavelength of the ultrasonic wave, which is specifically 12 mm.

• 한국공작기계학회논문집
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• 제13권3호
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• pp.53-60
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• 2004

We have developed and manufactured an experimental ultrasonic polishing machine with frequency of 20kHz at the power of vibration 1.7㎾ for effective ultrasonic polishing in processing of high hardness material. Design of the horn is performed by the FEM analysis. The following conclusions were empirically deduced through experimental results to clarify the major elements which affect the surface roughness during the ultrasonic process by following the experimental plans. The ultrasonic polishing machine has been developed in parts of structure part, ultrasonic generator, vibrator. We were able to process the high hardness material without difficulty as a result of ultrasonic polishing by utilizing the groove added step-type horn. Through analyzing by applying the experimental plans, the rotating speed of the horn was determined to be the major factor in influencing the surface roughness. In the case of ceramic, wafer, we were able to obtain good surface roughness when the feed rate and the ultrasonic output were higher. Because the load on slurry particle increases when the ultrasonic output is higher, the processed surface becomes worse in the case of optical glass.