• 한국음향학회지
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• 제14권6호
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• pp.62-67
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• 1995

본 논문에서는 금속내부에 존재하는 결함의 다양한 형태로부터 반사된 초음파 신호를 디지탈 신호처리에 의하여 특징추출하는 방법을 연구분석하였다. 다양한 형태의 결함으로부터 반사된 초음파 신호는 잡음 등의 영향으로 그 특징의 구별이 애매하므로 자기 회기법(auto-regressive)을 이용한 위너 필터링(Wiener filtering)과 최소 절대치 노름(least-absolute-values norm) 기법을 사용하여 신호의 특징을 추출하고 상호 비교분석하였다. 실험에서는 알루미늄 시편에 평면결함, 사각결함, 원형결함의 세가지 결함형태를 제작하였으며, 초음파를 입사하고 펄스-에코 방법에 의하여 반사신호를 측정하였다. 반사신호의 디지탈 신호처리 결과, 이러한 특징추출방법은 다양한 형태의 결함으로부터 반사된 신호를 효율적으로 분류 할 수 있었다.

• 분석과학
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• 제36권4호
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• pp.152-160
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• 2023

Adenosine and cordycepin are bioactive compounds with health benefits. Therefore, both substances are often used to assess the quality of Cordyceps products. Optimization and validation of the HPLC/DAD method for determining two nucleosides were studied. The samples were prepared using an ultrasound-assisted extraction (ultrasonic bath). The result was optimal conditions for aqueous extraction, an extraction time of 35 min, and an extraction temperature of 40 ℃. The Chromatographic separation was achieved using a reverse phase column (InfinityLab Poroshell 120 EC-C18, 4.6 × 250 mm, 2.7 ㎛) at 30 ℃ with a mobile phase gradient elution of water and methanol at a flow rate of 0.7 mL/min. The eluents were monitored via a diode array detector at 260 nm. Two nucleosides were separated by less than 12 min after injection. The developed method was found to be excellent linear (r² > 0.9999), accurate (% recovery 95.34-98.51), and precise (% relative standard deviation < 2.0). The limit of detection (LOD) and quantification (LOQ) were 0.45 and 1.38 mg/mL for adenosine and 0.47 and 1.43 mg/mL for cordycepin, respectively. This method was satisfactory for simultaneously quantitating two nucleoside contents, which were used to evaluate Cordyceps products.

• ALGAE
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• 제28권4호
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• pp.371-378
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• 2013

Water and methanolic extracts of Ecklonia cava, a marine brown alga, were prepared by ultrasonic extraction (UE) and conventional extraction (CE) methods. The radical-scavenging activity and the inhibitory effects against hydrogen peroxide ($H_2O_2$)-induced DNA damage of the extracts were investigated. All extracts prepared by CE exhibited higher total polyphenolic content than that in the extracts prepared by UE. Extraction yield and total phenolic content increased as the UE time increased. The radical-scavenging activities increased as the UE time increased. All extracts prepared by CE exhibited higher 1,1-diphenyl-2-pricrylhydrazyl (DPPH) and hydroxyl radical-scavenging activities than did those prepared by UE. Extracts prepared by UE showed stronger scavenging activities on alkyl radical and $H_2O_2$ than those prepared by CE did. Methanolic extract with UE 12 h (100MEU-12h) and methanolic extract with CE 24 h (100MEC-24h) were selected and evaluated by comet assay for their inhibitory effect against $H_2O_2$-induced DNA damage. 100MEU-12h showed slightly greater protective effect against $H_2O_2$-induced DNA damage than 100MEC-24h. Thus, UE can be effectively used as a seaweed extraction technique, and there is potential for scale-up of the extraction process.

• 한국환경과학회지
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• 제19권3호
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• pp.379-387
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• 2010

Sediments of Little Scioto (LS) River in Ohio was contaminated by poor disposal of creosote from Baker Wood Creosoting Facility. Among the primary compounds of creosote, Polycyclic Aromatic Hydrocarbons (PAHs) are the most common ingredient PAHs are known for toxic, carcinogenic and mutagenic compounds. There are many difficulties to remove the PAHs in nature environment because their characteristics are having a less water-solubility, volatile and low mobility properties as increasing the molecular weight. The generation of hydroxyl radicals (${\cdot}OH$) and hydrogen peroxide ($H_2O_2$) forms as well as high temperature (5000 K) and pressure (1000 atm) by a physico-chemical effects of ultrasound during a cavitation collapse can promote the degradation and desorption of PAHs in sediment And it can also produces shock wave and microjets which are able to change the size and surface of particle in solid-liquid system as one of physical effects. Therefore, we explored to understand the role of particle size, the effect of elimination for PAHs concentration by ultrasound and optimize the conditions for ultrasonic treatment. The condition of various size of particles (> $150{\mu}m$, < $150{\mu}m$) and solid-liquid ratio (12.5g/L, 25g/L) for the treatment was considered and ultrasonic power (430 W/L) with liquid - hexane extraction and microwave extraction method were applied after ultrasound treatment.

• Korean Chemical Engineering Research
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• 제55권4호
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• pp.542-547
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• 2017

초음파 추출법(Ultrasonic-assisted extraction, UAE)은 기존의 추출법 대비 높은 추출 효율과 짧은 추출시간으로 식물 세포벽으로부터 생리활성물질 추출 또는 분리에 효과적인 방법으로 인식되어 관심이 증대되고 있다. 본 연구에서는 탈지미세조류(Tetraselmis KCTC 12236BP)에서 폴리페놀 추출을 위해 UAE를 적용하여 총 폴리페놀(TPC) 생산에 미치는 주요 추출변수의 영향을 평가하였다. 추출변수의 최적화를 위해 입자크기, 고액비(L/S ratio), 에탄올 농도, 추출 온도 및 추출 시간을 요인으로 하여 순차적인 최적화를 진행하였다. 실험에 적용 된 모든 변수는 TPC 추출에 유의한 효과를 보였으며 추출 온도가 TPC생산에 가장 큰 영향을 미침을 확인 할 수 있었다. 최적 추출조건은 혼합 입자 사용 시, 10% 고액비, 60% 에탄올, 추출온도 $100^{\circ}C$와 추출시간 30 분을 적용한 추출에서 8.7 mg GAE/g DW를 얻을 수 있었다. 동일한 추출조건에서 열수추출과 UAE를 비교하였을 때 UAE에서 TPC 추출이 1.8배 증가함을 확인하였다. 본 연구를 통해 저온 및 짧은 추출시간을 적용한UAE가 기존의 열수추출 공정에 비해 LEA를 이용한 생리활성물질 생산에 보다 효과적임을 확인하였다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1993년도 학술논문발표회 논문집 제12권 1호
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• pp.169-173
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• 1993

In this paper, the features extraction of reflected signals from various type of defects existing in the solid has been studied by Wiener filtering technique. In this experiment, three types of the defect have been considered; a flat cut, a angular cut and a circular hole. All of the defects have the same size, 20mm in diameter and have been located at 45mm in depth from the aluminum surface. In the result of the experiment, it has been found that the wiener filtering technique used for features extraction from the reflected signal corresponding to each defect have been very effective for defect classification.

• 대한기계학회논문집A
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• 제24권1호
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• pp.52-61
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• 2000

The role of quantitative nondestructive evaluation of defects is becoming more important to assure the reliability and the safety of structure, which can eventually be used for residual life evaluation of structure on the basis of fracture mechanics approach. Although ultrasonic technique is one of the most widely used techniques for application of practical field test among the various nondestructive evaluation technique, there are still some problems to be solved in effective extraction and classification of ultrasonic signal from their noisy ultrasonic waveforms. Therefore, crack size determination through a neural network based on the back-propagation algorithm using back-scattered ultrasonic signals is established in this study. For this purpose, aluminum plate containing vertical or inclined surface breaking crack with different crack length was used to receive the back-scattered ultrasonic signals by pulse echo method. Some features extracted from these signals and sizes of cracks were used to train neural network and the neural network's output of the crack size are compared with the true answer.

• 한국환경과학회지
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• 제12권1호
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• pp.63-68
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• 2003

Effective alginate extraction from waste-brown seaweeds was studied. The waste-brown seaweeds almost consist of stems of seaweeds. Alginate could be obtained from the stems as well as leaves of seaweed. Ultrasonic vibration(47kHz) facilitated filtering step in the alginate extraction process. Among various alkalies for alginate extraction, $NaHCO_3$ was most appropriate concerning use of dealginates. The yield of alginate extraction using $NaHCO_3$ 2wt% solution was 19.3% at $60^{\circ}C$. The dealginates from $NaHCO_3$-extraction process have been found most suitable food for red-worms.

• 약학회지
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• 제56권4호
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• pp.217-221
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• 2012

To determination of antioxidant substance homoorientin, from Phyllostachys bambusoides leaves, the ultrasonic extraction and HPLC on-line $ABTS^+$ screening method were empolyed. Also, the various experimental variables such as the frequency and time of ultrasonic system were investigated and homoorientin was extracted efficiently at the low frequency 35 kHz and the extraction time 60 min. The values were positive peak 1574.71 (relative area, 23.67%) and negative peak 6924.34 (relative area, 1.23%), respectively. This HPLC on-line $ABTS^+$ screening method was rapid and efficient to search for antioxidants from natural products. These results will provide a database for investigating the constituents of natural products and the resources of pharmaceutical and cosmetic products.

• 한국약용작물학회지
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• 제23권2호
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• pp.155-160
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• 2015

This research evaluate antioxidant and skin-whitening effect of Abeliophyllum distichum Nakai by extraction processes. First, antioxidant effects were follows: EE (70% ethanol extract) showed higher DPPH scavenging activity of 69.66% than WE (hot water exract) 59.13% at $0.3mg/m{\ell}$, also UE's (70% ethanol extract by sonication process) higher than EE. Reducing power was that also EE showed higher than WE, and it was the highest value with UE's because of ultrasonic pretreatment. Next, the whitening effect tyrosinase inhibition activity was measured that EE was 23.88%, WE's was 16.69%, and UE was 23.34%. Ultrasonic pretreatment did not influence to tyrosinase inhibition activity. Cell viability showed low cell toxicity in all groups. UE's inhibited melanin synthesis, 55.1%, that is higher than EE and WE, 52.7% and 39.5%, respectively. As a result, we confirmed that antioxidant activities and skin-whitening effect by extraction process. Also, this results confirmed that the Abeliophyllum distichum Nakai extracts worth as cosmetic materials.