• 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.

• 한국정밀공학회지
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• 제13권11호
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• pp.38-45
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• 1996

In recent years, ultrasonic has been widely applied in measurement and industrial fields and its application range has been expanded as a result of continuous research and development. Wire Bonding Machine, an instrument fabricating semi-conductor, makes use of ultrasonic bonding method. Specially, the method utilizes the longitudinal vibration of ultrasonic transducer composed of piezoelectric vibrator and horn. This work investigates the design conditions affecting the dynamic characteristics through the theretical and experimental analysis. It conducts separately the system identification of piezoelectric vibrator in time domain and the modal analysis of horn in frequency domain. The integrated modeling is conducted via a combbination of dynamic identification of piezoelectric vibrator and theroretical analysis of horn. Then comparison is made for theroretical and experimental results of the dynamic characteristics of the ultrasonic transducer comprised of piezoelectric vibrator and horn. Form the results of the comparison we develop the design technique of ultrasonic transducer using dynamic characteristics analysis and propose the possibility of ultrasonic bonding considering the optimal conditions for the longitudinal vibration of ultrasonic transducer and other conditions.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.571-576
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• 1994

In recent years, ultrasonic has been widely applied in measurement and industrial fields and its application range has been expanded as a result of continuous research and development. Wire Bonding Machine, an instrument fabricating semi-conductor, makes use of ultrasonic bonding method. In order to improve the currently used wire bonding machine using ultrasonic energy, technical accumulation is needed steadily through development of exciting device of ultrasonic composed of piezoelectic vibrator and horn. This study investigates the design conditions affecting the dynamic characteristics through the theoretical and experimental analysis of piezoelectric vibrator and horn, The study conducts separately the system identification of piezoelectric vibrator in time domain and the modal analysis of horn in frequency domain. In theoretical model, the integrated modeling is conducted via a combination of dynamic identification of piezoelectric vibrator and theoretical analysis of horn. Hence comparison is made for theoretical and experimental results of the dynamic characteristics of the ultrasonic transducer composed of piezoelectric vibrator and horn. Form the results of this study we develop the design technique of ultrasonic transducer using dynamic characteristic analysis and propose the possibility of ultrasonic welding considering the optimal condition of the natural frequency and vibration mode of horn.

• 한국환경복원기술학회지
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• 제16권6호
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• pp.135-143
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• 2013

Ultrasonic mist fogger and the fan were used for investigating the availability of fog circulation system in greenwall and the potential growing ability of the plant. The mist caused by ultrasonic mist fogger was circulated by the fan through the pipeline and supplied to the pots containing plants. Moisture content of the 3 different soils was measured at different irrigation time points. The moisture content of 15-26% in PP and Co soil was maintained at irrigation of 24H, 18H, 12H in a day. Proper growth condition was found in Ardisia pusilla and Hosta plantaginea at the height of L level after 1 month of growth when the plants were irrigated by the fog circulation system. The results suggest that the fog circulation, by ultrasonic mist fogger to the green walls is system of choice for suppling moisture to plants.

• 한국정보통신학회논문지
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• 제12권9호
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• pp.1564-1568
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• 2008

크레인의 운영에 있어 효율적인 운전과 안전을 위한 장비 중의 하나가 충돌 방지 시스템이다. 이 시스템의 대부분은 초음파를 이용하여 거리를 측정하여, 크레인의 위치와 충돌을 방지하기 위해 사용되고 있다. 그러나, 초음파를 이용한 충돌 방지 시스템은 온도와 습도의 변화에 의해 성능의 신뢰성이 저하된다. 따라서 본 연구에서는 온/습도 변화에 따른 거리측정의 성능과 안정성의 개선을 위해 신경망을 이용한 크레인 충돌방지 시스템을 제안하고 성능을 평가하였다. 실험의 결과에서 제안된 기법이 기존의 온도 보상의 기법보다 안정성과 정밀도가 향상됨을 보였다.

• 한국압력기기공학회 논문집
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• 제6권1호
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• pp.23-28
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• 2010

To enhance the reliability of ultrasonic testing system, MOST(Ministry of Science and Technology) bulletin 2004-13 was published in 2004.6 requiring performance demonstration in ultrasonic examination and MEST(Ministry of Education, Science and Technology) 2009-37 was published in 2009.9(formerly MOST bulletin 2004-13). In order to meet the MEST bulletin requirement and increase the reliability of ultrasonic testing, all the ultrasonic examination procedure and equipment should be performance demonstrated and qualified. In this paper, generic procedure for the ultrasonic examination of dissimilar metal welds are described and new technique are introduced.

• 비파괴검사학회지
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• 제11권2호
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• pp.42-47
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• 1991

Nondestructive evaluation study was made on creep damage materials by ultrasonic spectrum analysis. The evaluation methods was developed in order to predict the change of ultrasonic attenuation with increasing creep damage. A new algorithm for the improvement of measuring accuracy of ultrasonic attenuation using a spectrum analysis has been developed. Normally, the ultrasonic attenuation is evaluated from 1st and 2nd peak values of the pulse-echo ultrasonic wave. The algorithm developed is incorporated in a measuring system which consists of a personal computer with ultrasonic apparatus and a digital storage oscilloscope. By the spectrum analysis method, it become popssible to describe approximately the attenuation change with increassing creep damage in Cr-Mo-V forging.

• 대한기계학회논문집A
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• 제27권1호
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• pp.138-143
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• 2003

Ultrasonic flowmeters have more advantages than the conventional method using pressure-difference. In these reasons, many advanced nations are already selling the commercial model. In RIST, we have been developed ultrasonic gas flow meter for the localization since a project was been contracted with POSCO in 1997. This paper describes a new ultrasonic gas flowmeter. This ultrasonic gas flowmeter is developed for accurate measurement of gases in a harsh environmental conditions. It is especially suited for measuring LDG. COG, BFG gases produced in iron & steel making process. In this study, we had developed the commercial model about the first tested model and applied a completed system to the POSCO gas line. Its performance has been proven by extensive field tests for several months in POSCO, iron & steel making company.

• Tribology and Lubricants
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• 제19권5호
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• pp.285-291
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• 2003

Ultrasonic vibrator is an equipment which atomizes and homogenization the oils by breaking the oil particles with ultrasonic cavitation, and would improve the properties. The present study deal with the ultrasonic breaking systems which recycle the shipborne waste oil into usable oil to be burnt. The first place, experimental studies were carried out to investigate the homogenizing effect of the waste oils by ultrasonic cavitation. Variation of the properties(viscosity, specific gravity and pH) and the matrix structures for the various shipborne waste oils were interpreted to analyse the breaking, dispersion effects by ultrasonic cavitation. The experimental results can be useful to the development of waste oil disposing systems.

• 한국자동차공학회논문집
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• 제5권2호
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• pp.42-49
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• 1997

This experimental study was performed to find fuel property variations of the ultrasonic energy adding gasoline and improve the spray characteristics of the multipoint injector for EFI engine. The cause and effect of the characteristic improvement of the ultrasonic energy adding fuel was found out by the chemical structure analysis (NMR, IR), distillation and viscosity test. The results are obtained that the chemical property of gasoline organizition was changed aromatics to paraffins and branch index as the physical characteristics of gasoline were improved by ultrasonic energy. There were higher distillation and lower viscosity in ultrasonic energy adding gasoline.