• Journal of Energy Engineering
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• v.18 no.3
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• pp.169-174
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• 2009

In the study, the effect of the ultrasonic energy in transportational diesel fuel on the engine performance and exhaust emission has been investigated for indirect injection diesel engine. It was tested to estimated change of engine performance and exhaust emission characteristics for the transportational diesel fuels and the reforming fuels which was irradiated by the ultrasonic energy. The results of the study may be concluded as follows; By the irradiation of ultrasonic energy on the diesel fuel, cylinder pressure, heat release rate and engine power were increased but bsfc, mass fraction burned, and smoke were reduced. Also, the combustion was more stabilized and became complete and NOx was increased.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.532-535
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• 2009

In this study, the fatty acid methyl ester was prepared from the vegetable oil by inducing ultrasound energy. The ultrasound energy was applied to the esterification reaction for heating and stirring effects. Ultrasonic induction results in the shortened reaction time and brings the increase of the methyl ester yield. However, the continuous introduction of ultrasound during the esterification reaction results in temperature increase, then the over-heating of reaction temperature was ineffective. Therefore, the system temperature was controlled at constant temperature state with the cooling circulation. The ultrasound induction reaction had the fatty acid methyl ester yield of 93% at the reaction time was 30 minutes, faster than the traditional esterification process.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.408-416
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• 2021

In the ultrasonic dispersion, in order to avoid direct contact of the radiation surface of ultrasonic transducers with a liquid sample, the liquid sample is separated by a glass container and it receives ultrasonic energy through an acoustic medium. The transmission efficiency of the ultrasonic energy in the multi-layered ultrasonic system is an important factor. In this study, we suggested a method that can improve the ultrasonic energy transfer efficiency by using a propylene glycol solution as a liquid matching layer in the multi-layered acoustic system. In this method, a propylene glycol solution was filled between the Langevin-type ultrasonic transducer and the luminol solution and the sonoluminescence phenomena in the luminol solution, which is caused by nonlinear effect of high power ultrasound radiated from the transducer, was examined by using a Photo Multiplier Tube (PMT). The transmission efficiency depending on the concentration of propylene glycol solution was observed, and we can see that as the concentration of the propylene glycol solution increased, the matching effect increased while the acoustic attenuation increased. It was confirmed that there is an optimal concentration compromised these two conflicting conditions, and the optimum concentration of the propylene glycol solution was determined experimentally.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2003.02a
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• pp.434-439
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• 2003

20세기 후반부에 이르러 초음파는 과학 및 산업분야 전반에 걸쳐 다각도로 활용 및 응용되고 있다. 본 연구는 초음파를 이용한 분무입경의 미세화 및 균일입경의 분무를 위한 초음파 응용기기의 설계를 위한 선행연구로서 초음파 에너지에 의한 고형성분의 파쇄여부를 측정하였다. 초음파 에너지를 부가한 후, 즉 초음파 처리된 상태에서의 수화제의 물리적인 파쇄특성을 광학현미경과 SEM을 이용하여 관찰하였다. (중략)

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06d
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• pp.35-39
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• 1998

Methyl과 ethyl formate의 초음파 흡수계수를 0.15-2 MHz의 주파수 범위, 온도 5-3$0^{\circ}C$에 걸쳐 1MHz 이하에서 정확한 초음파 흡수측정이 가능한 광 회절 초음파 공명법을 이용하여 측정하였다.그 결과, cisdhk trans 에 의한 초음파 완화 현상은 전형적인 단일 완화현상을 보였고, 그 스페트럼으로부터 완화주파수와 완화강도를 결정할 수 있었다. 완화 주파수와 완화강도의 온도 의존성으로부터 활성화 에너지(ΔH#)와 에너지 차(ΔH)를 구하였다. 측정된 methyl과 ethyl formate의 활성화 에너지는 각각 9.8과 8.9kcal/mol 이었고, 에너지 차는 각각 2.3 과 2.2kcal/mol로 나타났다

• Journal of Wetlands Research
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• v.16 no.2
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• pp.205-212
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• 2014

Ultrasound technology can be applied in various fields including environmental, energy, and material engineering processes. In this study the effect of liquid height/volume on calorimetric energy and sonochemical oxidation was investigated as one of the basic steps for the design of water/wastereater treatment sonoreactors. The liquid height was increased from 0 to $4{\lambda}$ by $1/4{\lambda}$ and it was found that both calorimetric energy and sonochemical oxidation were significantly increased at relatively high liquid height/volume where the power density was relatively low. The sonochemiluminescence (SCL) images for the visualization of the activity of cavitation also showed that larger and more stable active zone was formed with high SCL intensity at high liquid height/volume. Therefore, it was revealed that sonoreactors for water/wasterwater treatment could be significantly effective in terms of removal efficiency and energy consumption.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.155-160
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• 2011

An animal fat is an attractive biodiesel energy source for its high stability against oxidation and low incomplete combustion ratio due to the high heating value and cetane value. However, it requires a refinery process because of the high content of saturated acid and impurity which increas the boiling point. In this study, the optimum biodiesel synthetic process of lard is suggested. Indeed, we demonstrate new biodiesel production processes to alter conventional process of heating and mixing by applying ultrasonic energy. While the optimum reaction temperature and mole ratio of methanol and lard, when using conventional mixing and heating process, were $55^{\circ}C$ and 12, respectively, the reaction time were reduced to 30 minutes by applying ultrasonic irradiation power of 500 W. The new process applying ultrasonic irradiation yielded synthetic biodiesel properties as followings: 3.34 cP of the viscosity, 37.0 MJ/kg of the caloric value and below 0.25 mgKOH/g of the acidic value, which satisfy biodiesel quality criteria.

• KSBB Journal
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• v.19 no.6 s.89
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• pp.421-426
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• 2004

The extraction and separation of isoflavones from Korean soybean were peformed by various mechanical and chemical extraction methods. They included solvent extraction, stirring, supersonification and sub/supercritical water extraction. From the experimental results of the variation of solvent extraction by change in composition, the increase in extraction of a specific compound by stirring or supersonic energy, and the application of supercritical fluid with superior solvating power over solvents, the sonification was the most desirable extraction method in extracting aglycone isoflavones, daidzein and genistein from Korean soybean.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.464-470
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• 2002

본 연구에서는 초음파를 사과의 비파괴 품질판정에 이용하기 위한 기초 연구로서 사과 표면에 입사, 반사되는 초음파 신호를 계측 및 분석하기 위한 시스템을 구축하고 저장기간에 따른 사과의 초음파 특성을 계측하였으며, 그 결론은 다음과 같다. 1. 구성된 비 접촉식 초음파 장치를 이용하여 전압-시간 그래프에서 전압의 진폭(PTP)값을 구하였고 신호처리용 프로그램을 이용하여 획득한 신호를 주파수 영역에서 분석하여 피크주파수, 영역별 에너지 밀도함수 등을 구하였다. 2. 사과의 초음파 특성을 분석한 결과 사과의 저장기간은 초음파 응답신호의 진폭(PTP) 및 제 3영역 에너지 스펙트럼 밀도함수와 높은 상관성이 있는 것으로 나타났다. 3. 초음파를 농산물의 비파괴 품질판정에 적용시 문제가 되고 지는 센서와 시료와의 접촉응력에 의한 응답신호의 변형에 의한 문제를 해결하고자 비 접촉식 센서를 사용하였으며, 실제 농산물에 적용이 가능한 것으로 판단되었다.

• Geophysics and Geophysical Exploration
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• v.7 no.4
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• pp.225-233
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• 2004

The purpose of this study is to provide the geo-technical information by assessment of the in-situ rock strength using the reflected wave energy and travel time data acquired by the borehole acoustic scanner. In order to compare and analyze the relationship between the uniaxial compressive strength and the reflected wave energy, the laboratory test and the borehole acoustic scanning were conducted for the set of specimens, such as mortar, concrete, and rock samples which have different rock type. Finally, we verified the applicability of the reflected wave energy acquired by the borehole acoustic scanner to quantitatively estimate the in-situ rock strength.