• Journal of environmental and Sanitary engineering
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• v.13 no.1
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• pp.1-8
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• 1998

Musty-odorous compound (Geosmin, 2-Methylisobrneol) 수용액 중에 초음파 (200kHz, $6.0W/cm^{2}$)를 조사시켜 조사시간에 따른 농도 및 취기의 변화를 고찰했다. 초음파 조사에 의해 이 물질들은 빠르게 분해되었고 분해 형태는 농도에 대한 유사1차 반응을 나타내었다. 공기 포화 분위기에서 이들의 초기 분해속도는 각각 2.5 $10^{-3}{\;}Msec^{-1}$(2-MIB), 3.2 $10^{-3}{\;}Msec^{-1}$ (Geosmin)로 나타났다. 초음파 조사 시 포화가스 (Envelope gas)의 영향은 아르곤(Ar) 산소($O_{2}$) 공기(Air) 질소($N_{2}$) 순서로 순수한 아르곤(Ar) 분위기에서 musty-odorous compound 류의 분해가 가장 빠르게 진행되었고 그 분해생성물로 CO, $CO_{2}$ 그리고 HCOOH, $CH_{3}COOH$ 등의 저급 유기산류가 검출되었다. 또한 이들의 분해반응은 물의 초음파분해에 따라 생성된 hydroxylradical에 의한 radical반응, cavitation bubble내에서의 고온고압에 의한 열분해 및 직접연소반응으로 진행됨을 알 수 있었다.

• Transactions of the KSME C: Technology and Education
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• v.1 no.1
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• pp.115-121
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• 2013

It is greatly expected that the technologies of durability enhancement and evaluation for the core structures of plant facilities, marine plant and bridge constructures will be greatly expanded in the plant industry fields. In this study, the actively ongoing applied cases were tried to be analyzed in the present domestic industry fields through the Ultrasonic Nanocrystalline Surface Modification (UNSM) and Ultrasonic Fatigue Test (UFT) technologies using ultrasonic elastic vibrational energy, and the new application technology to improve the durability of plant industry field, especially plant facilities, marine plant and core weld components of bridge constructures will be presented.

• Korean journal of applied entomology
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• v.51 no.3
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• pp.223-230
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• 2012

Some high frequency sounds alter physiological processes of the beet armyworm, Spodoptera exigua. This study investigated the effect of ultrasound (${\geq}$ 20 kHz) on larval feeding, pupal development, and adult mating behavior of S. exigua. Ultrasound suppressed feeding behavior of fifth instar larvae, and 30 or 45 kHz treatment inhibited more than 50% of feeding activity. Larvae treated with ultrasound exhibited alterations in major nutrient compositions in the hemolymph plasma. Plasma protein levels decreased with an increase in ultrasound frequency. In contrast, sugar levels increased with an increase in ultrasound frequency. Lipid levels increased with an increase in ultrasound frequency up to 30 kHz and then decreased at treatments > 30 kHz. Hemocytes, the fat body, and epidermis expressed three heat shock proteins and apolipophorin III. Ultrasound treatment markedly inhibited expression of some stress-related genes. Ultrasound treatment also inhibited S. exigua pupal development by extending the pupal developmental period and preventing adult emergence. Last, ultrasound treatment significantly inhibited adult mating behavior, which resulted in a significant decrease in female fecundity. These results show that ultrasound is a physiological stress to S. exigua.

• Journal of agriculture & life science
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• v.44 no.5
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• pp.91-99
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• 2010

The objective of this work was to investigate the influence of ultrasonification on extraction yield and chemical properties of green tea infusion. Changes in total soluble matter(TSM), vitamin C, total phenolic compounds, flavonols, catechins, caffeine, free amino acids contents in green tea infusion(GTI) influenced by ultrasonification at $60^{\circ}C$ of extraction temperature for 1, 5, 30, and 60 min were investigated. The amount of infused TSM increased about 5.3% by ultrasonification for 60min. Vitamin C contents also increased 0.21, 0.16, 0.31 mg/g from 1 to 30 min by ultrasonification. However, vitamin C decreased from 2.47 to 2.22 mg/g at 60min. Total phenol compounds contents increased about 10~13 mg/g on all extraction times by ultrasonification. Flavonols such as, myricetin, quercetin, kaempferol were increased to doubled contents as an influence of ultrasonification. Catechins such as, EGCG, EGC, ECG, EC, (+)-C and caffeine contents showed same tendency as the results of vitamin C. On the other hand, result of free amino acids showed different tendency. All amounts of free amino acids did not increase by ultrasonification. Consequently, content of bioactive compounds such as, vitamin C, total phenolic, flavonols and catechins in green tea infusion were influenced by ultrasonification.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.1
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• pp.20-26
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• 2005

Ultrasonic guided waves have been widely employed for long range inspection of structures such as plates, rods and pipes. There are numerous modes with different wave velocities, and the appropriate mode selection is one of key techniques in the application of guided waves. In the present work, phase tuning by an array transducer was applied to generate ultrasonic guided waves. For this purpose, 8-channel ultrasonic pulser/receiver and their controller which enables sequential activation of each channels with given time delay were developed. Eight transducers were fabricated in order to generate guided waves by using an array transducer. The selective tuning of wave mode can be achieved by changing the interval between elements of an array transducer.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.2
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• pp.122-129
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• 2009

Recently much attention has been paid to a guided wave due to its effective applicability to long range and fast inspection of structures. In guided wave based NDE, the appropriate selection of wave modes is one of important factors since the test performance is highly dependent on which mode of guided waves is employed. As far as plate-like structures are concerned, so far, SH guided wave has not been frequently applied compared to Lamb waves, which is mostly caused by the lack of proper and convenient transducers to generate and measure the SH waves. In this investigation, a new small-sized SH guided wave transducer based on magnetostriction is proposed. The present transducer was designed to be modular and be used with shear couplant to avoid the inconvenience of the existing magnetostrictive patch transducers, which comprises the ferromagnetic patch tightly bonded to a structure. The wave transduction mechanism and the detailed configuration of the present transducer are presented. Experimental verification is also conducted on test specimens and the results confirm the good performance of the present transducer module.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.4
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• pp.78-84
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• 1996

In this study, 3-D object recognition and restoration independent of the object translation for automotive kind recognition in parking administration system using an ultrasonic sensor array, neural networks and invariant moments are presented. Using invariant moment vectors of the acquired data 16$\times$8 pixels, 3-D objects could be classified by SCL (Simple Competitive Learning) neural networks. Modified SCL neural networks using the 16$\times$8 low resolution image was used for object restoration of 32$\times$32 high resolution image. Invariant moment vectors kept constant independent of the object translation. The recognition rates for the training and the testing data were 98[%] and 95[%], respectively. The experimental results have shown that ultrasonic sensor array with the neural networks could be applied for the detection of the automobiles and classification of the automotive kind.

• 기계와재료
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• v.10 no.1 s.35
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• pp.85-92
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• 1998

• Journal of the korean veterinary medical association
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• v.40 no.8
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• pp.696-707
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• 2004

• The Magazine of the IEIE
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• v.40 no.6
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• pp.64-72
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• 2013