• 대한청각학회지
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• 제24권2호
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• pp.79-84
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• 2020

Background and Objectives: Hearing can be elicited in response to vibratory stimuli delivered to fluid in the external auditory meatus. To obtain a complete audiogram in subjects with normal hearing in response to pure tone vibratory stimuli delivered to fluid applied to the external meatus. Subjects and Methods: Pure tone vibratory stimuli in the audiometric range from 0.25 to 6.0 kHz were delivered to fluid applied to the external meatus of eight participants with normal hearing (15 dB or better) using a rod attached to a standard clinical bone vibrator. The fluid thresholds obtained were compared to the air conduction (AC), bone conduction (BC; mastoid), and soft tissue conduction (STC; neck) thresholds in the same subjects. Results: Fluid stimulation thresholds were obtained at every frequency in each subject. The fluid and STC (neck) audiograms sloped down at higher frequencies, while the AC and BC audiograms were flat. It is likely that the fluid stimulation audiograms did not involve AC mechanisms or even, possibly, osseous BC mechanisms. Conclusions: The thresholds elicited in response to the fluid in the meatus likely reflect a form of STC and may result from excitation of the inner ear by the vibrations induced in the fluid. The sloping fluid audiograms may reflect transmission pathways that are less effective at higher frequencies.

• 한국멀티미디어학회논문지
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• 제25권8호
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• pp.1022-1037
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• 2022

It is important to develop a transducer that generates uniform output power through frequency control of the HIFU at 4 MHz frequency for the high intensity focused ultrasound (HIFU) skin diseases treatment. In this paper, a 4 MHz frequency band HIFU system for skin disease treatment was designed, manufactured and developed. In HIFU, even for the ultrasonic vibrator in the 4 MHz frequency band, the characteristics of the output power of the HIFU are different depending on the difference in the thickness of the PZT material. Through the development of a system amplifier, the sound output of the HIFU transducer was improved to more than 48 W and uniform output power control was possible. And, it is possible to control the output power even in a frequency band of 4.0 to 4.7 MHz, which is wider than 4.0 MHz, and shows the resonance frequency of the transducer. The maximum output power for each frequency was 49.969 W and the minimum value was 48.018 W. The maximum output power compared to the minimum output power is 49.969 W, which is uniform within 4.1%. It was confirmed that the output power of the HIFU through the amplifier can be uniformly controlled in the 4 MHz frequency band.

• 한국음향학회지
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• 제26권2호
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• pp.95-101
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• 2007

본 논문에서는 구조물의 손상탐지를 위한 두께 방향 모드 압전 오실레이터의 가능성을 연구하였다. 두께 방향 모드 오실레이터 센서는 구조물의 주요부에 부착된 두께 방향 모드 압전소자와 피드백 오실레이터 회로로 구성되어있다. 구조물의 손상은 구조물의 임피던스를 변화를 야기시키며, 그 결과로 구조물의 공진 주파수가 변하게 된다. 오실레이터 센서는 간단한 방법으로 이 공진 주파수 변화를 연속적으로 관측할 수 있다. 본 연구에서는 알루미늄 시편에 크랙의 크기와 개수를 인위적으로 변화시키면서, FEM해석과 실험을 통해 두께 방향 모드 압전 오실레이터 센서의 적용 가능성을 증명 하였다.

• 한국음향학회지
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• 제14권4호
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• pp.29-37
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• 1995

높은 결합계수를 가진 압전진동자의 전기단자에 전기적 임피던스를 결합하면 공진주파수가 크게 변화한다. 본 연구에서는 이 현상의 해석을 위하여 전기단자의 부하상태를 고려한 새로운 전송선로형 등가회로를 제안하고, 그 등가회로의 유효성을 실험적으로 확인하였다. 실험에 있어서는 2층구조의 주파수 가변형 PZT 트랜스듀서를 제작, 그 전기단자에 접속시킨 임피던스의 변화에 따른 공진주파수의 변화와 실효감쇠량을 측정하였다. 제작된 트랜스듀서의 공진주파수는 180 KHz~580KHz의 넓은 주파수 대역에서 연속적으로 변화하고, 330KHz~470KHz에서의 실효감쇠량은 7dB이하의 높은 효율을 나타내었는데, 이 결과는 제안한 등가회로에 의한 해석결과와 잘 일치하였다.

• Clinical and Experimental Reproductive Medicine
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• 제43권3호
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• pp.146-151
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• 2016

Objective: This study was conducted to compare the effects of static culture, dynamic culture, and the combination of dynamic culture with specialized surfaces involving co-culture on human embryonic development. Embryos cultured using conventional static culture (SC) techniques served as a control group. We compared dynamic culture using micro-vibration culture (MVC) and micro-vibration with co-culture (MCoC), in which autologous cumulus cells were used as a specialized surface. Methods: We conducted a chart review of patients who were treated between January 2011 and November 2014 in order to compare embryonic development rates and pregnancy rates among the groups. Zygotes were cultured in micro-droplets, and embryos were subsequently selected for transfer. Some surplus embryos were cryopreserved, and the others were cultured for blastocyst development. A micro-vibrator was set at the frequency of 42 Hz for duration of 5 seconds per 60 minutes to facilitate embryo development. Results: No significant differences among the groups were present in patient's characteristics. However, the clinical pregnancy rates were significantly higher in the MVC group and the MCoC group than in the SC group. No significant differences were found in the blastocyst development rate between the SC group and the MVC group, but the blastocyst development rate in the MCoC group was significantly higher than in the SC and MVC groups. Conclusion: The clinical pregnancy rate was significantly increased by the application of micro-vibration to the embryonic cultures of poor responders. The blastocyst development rate was significantly increased by the application of MCoC to surplus embryos.

• 수산해양기술연구
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• 제31권4호
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• pp.413-422
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• 1995

각종 환경 조건에서 진동 캐비테이션 침식-부식 시험 장치에 의해 연강(SS41)의 캐비테이션 침식-부식 손상 거동에 관한 연구를 한 결과 다음과 같은 결론을 얻었다. 1) 해수 중에서 캐비테이션 침식-부식 손상 거동은 중앙부와 테두리 부에서 거의 비슷한 정도로 발생하여 성장되지만, 증류수 중에서는 테두리부에서 손상이 먼저 발생한 다음 중앙부에도 손상이 점차 일어난다. 2) 비저항이 낮은 수도수 중의 캐비테이션 침식-부식 손상은 초기에는 비저항이 높은 증류수중에서의 것보다 증가하지만 시간이 경과하면서 CaCO 하(3)의 피막 형성에 의해 둔화된다. 3) 케비테이션 침식-부식 손상 특성은 잠복기, 증가기, 감소기 및 안정기의 4단계로 구분된다.

• Natural Product Sciences
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• 제21권2호
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• pp.93-97
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• 2015

The purpose of this study was to develop a new ginseng (Panax ginseng) flower buds extract with the high concentration of ginsenoside Rg3, Rg5, Rk1, Rh1 and F4, the Red ginseng special component. Chemical transformation from the ginseng saponin glycosides to the prosapogenin was analyzed by the HPLC. The ginseng flower buds were processed at the several treatment conditions of the ultrasonication (Oscillator 600W, Vibrator 600W) and vinegar (about 14% acidity). The result of UVGFB-480 was the butanol fraction of ginseng flower buds that had been processed with ultrasonication and vinegar for 480 minutes gained the highest amount of ginsenoside Rg5 (3.548%), Rh1 (2.037%), Rk1 (1.821%), Rg3 (1.580%) and F4 (1.535%). The ginsenoside Rg5 of UVGFB-480 was found to contain 14.3 times as high as ginseng flower buds extracts (GFB, 0.249%).

• Journal of Biosystems Engineering
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• 제31권6호
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• pp.514-523
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• 2006

Production of green pepper has been increased due to customer's preference and a projected ten-year boom in the industry in Korea. This study was carried out to develop an automatic grading and sorting system for green pepper using machine vision. The system consisted of a feeding mechanism, segregation section, an image inspection chamber, image processing section, system control section, grading section, and discharging section. Green peppers were separated and transported using a bowl feeder with a vibrator and a belt conveyor, respectively. Images were taken using color CCD cameras and a color frame grabber. An on-line grading algorithm was developed using Visual C/C++. The green peppers could be graded into four classes by activating air nozzles located at the discharging section. Length and curvature of each green pepper were measured while removing a stem of it. The first derivative of thickness profile was used to remove a stem area of segmented image of the pepper. While pepper is moving at 0.45 m/s, the accuracy of grading sorting for large, medium and small pepper are 86.0%, 81.3% and 90.6% respectively. Sorting performance was 121 kg/hour, and about five times better than manual sorting. The developed system was also economically feasible to grade and sort green peppers showing the cost about 40% lower than that of manual operations.

• 한국전자통신학회논문지
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• 제8권5호
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• pp.757-762
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• 2013

본 연구는 앞 뒤 진동기기를 이용한 자세별 진동운동이 신체질량지수와 신체조성의 변화에 미치는 영향을 알아보고자 20대 남녀 41명을 대상으로 총 4개 군으로 나누어 4주 동안 실시하였다. 연구대상자는 각각 서기자세군(10명), 기마자세군(10명), 네발기기자세군(10명), 복합운동군(10명)으로 구분하여 실시하였으며, 운동 전 후 신체질량지수(BMI), 엉덩이에 대한 허리둘레 비(WHR), 체지방량 변화를 측정하였다. 연구 결과, 서기자세군, 기마자세군, 네발기기자세군 그리고 복합운동군에서 모두 신체질량지수, 엉덩이에 대한 허리둘레 비, 체지방량이 감소하였지만 복합운동군에서만 모든 항목에서 유의한 차이를 보였다(p<.05). 이를 통해 여러 가지 자세를 혼용한 진동운동이 비만 조절에 효과가 있는 것으로 확인 할 수 있었다.

• 한국기계가공학회지
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• 제12권4호
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• pp.75-80
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• 2013

Single crystal sapphire being used in high technology industry is a brittle material with a high hardness and excellent physical properties. ELID(Electrolytic In-Process Dressing) grinding technology was applied to material removal machining process of single crystal sapphire wafer. Ultrasonic vibration which added to material using ultrasonic table was adopted to efficient ELID grinding of sapphire materials. The evaluation of the ground surface of single crystal sapphire wafer was carried out by means of surface measuring by using AFM(Atomic Force Microscope), surface roughness tester and optical microscope device. As the results of experiment, it was shown that more efficient grinding was conducted when using ultrasonic table. In case of using #170 grinding wheel, surface roughness of ELID ground specimen in using ultrasonic table was superior to ELID ground specimen without ultrasonic table. However, In case of using #2000 grinding wheel, surface roughness of ELID ground specimen in using ultrasonic table was inferior to ELID ground specimen without ultrasonic table.