• Steel and Composite Structures
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• v.25 no.1
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• pp.93-104
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• 2017

In the present work, the effect of hygrothermal aging on the glass fibre and epoxy matrix interface has been investigated by destructive and non-destructive techniques. The glass fiber reinforced polymer (GFRP) composite laminates were prepared using Vacuum Assisted Resin Infusion Molding (VARIM) technique and the specimens were immersed in simulated seawater, followed by quantitative measurement. Besides this, the tensile tests of GFRP specimens revealed a general decrease in the properties with increasing aging time. Also, exposed specimens were characterized by a non-destructive ultrasonic guided Lamb wave propagation technique. The experimental results demonstrate a correlation between the drop in ultrasonic voltage amplitude and fall in tensile strength with increasing time of immersion. Hence, the comparison of the transmitted guided wave signal of healthy vis-a-vis specimens subjected to different extents of hygrothermal aging facilitated performance evaluation of GFRP composites.

• Journal of information and communication convergence engineering
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• v.20 no.1
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• pp.58-64
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• 2022

Breast ultrasonic reading is critical as a primary screening test for the early diagnosis of breast cancer. However, breast ultrasound examinations show significant differences in diagnosis based on the difference in image quality according to the ultrasonic equipment, experience, and proficiency of the examiner. Accordingly, studies are being actively conducted to analyze the texture characteristics of normal breast tissue, positive tumors, and malignant tumors using breast ultrasonography and to use them for computer-assisted diagnosis. In this study, breast ultrasonography was conducted to select 247 ultrasound images of 71 normal breast tissues, 87 fibroadenomas among benign tumors, and 89 malignant tumors. The selected images were calculated using a statistical method with 21 feature parameters extracted using the gray level co-occurrence matrix algorithm, and classified as normal breast tissue, benign tumor, and malignancy. In addition, we proposed five feature parameters that are available for computer-aided diagnosis of breast cancer classification. The average classification rate for normal breast tissue, benign tumors, and malignant tumors, using this feature parameter, was 82.8%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.6
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• pp.119-126
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• 2014

Micro-holes of conductive ceramic are required in micro structures. Micro-electrical discharge machining (Micro-EDM) is an effective machining method since EDM is as process for shaping hard metals and complex-shaped holes by spark erosion in all kinds of electro-conductive materials. However, as the depth of micro hole increases, the machining condition becomes more unstable due to inefficient removal of debris between the electrode and the workpiece. In this paper, micro-EDM was performed to evaluate machining characteristic such as electrode wear, machining time, taper angle, radial clearance with varying voltage and ultrasonic vibration on 10 vol.% Carbon-nanotube reinforced conductive $Al_2O_3$ composite fabricated by spark plasma sintering in previous research.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.149-150
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• 2011

미세화된 반도체 배선에 무전해 은도금을 적용하고자 새로운 Pd 활성화 공정을 제안하였다. 시편 표면에 작은 크기의 Pd 입자를 균일하게 분포시키기 위하여 Pd 활성화 도중 초음파을 가하였다. 추가적인 무전해 은 도금을 실시하여, 초음파에 의한 Pd 입자 분산이 은도금 피막 형성에 미치는 영향에 대하여 고찰하였다.

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.542-547
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• 2017

Ultrasound-assisted extraction (UAE) has attracted growing interest, as it is an effective method for the rapid extraction of bioactive compounds from plants with a high extraction efficiency comparable to the conventional extraction. In this study, UAE was used for the extraction of polyphenols from lipid extracted microalgae (Tetraselmis KCTC 12236BP) and the effects of five extraction variables on the total phenolic compounds (TPC) were studied. For the optimization of extraction parameters, particle size, solid-to-liquid (L/S) ratio, ethanol concentration, extraction temperature and extraction time have been examined as independent variables. All variables exhibited the significant effects on the extraction of TPC and extraction temperature showed the most significant effect among five variables. The optimal extraction conditions were the extraction using mixed particle, S/L ratio of 10%, ethanol concentration of 60%, extraction temperature of $100^{\circ}C$ and extraction time of 30 min, which gave the 8.7 mg GAE/g DW for TPC. Compared with conventional hot-water extraction, TPC extraction under UAE was increased by up to 1.8 fold with same extraction condition. This study showed that UAE under low temperature and short extraction time was proven to be an effective extraction process for TPC production from LEA compared to conventional hot-water extraction process.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.481-485
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• 2014

The applicability of the dipping, ultrasonic-assisted, heating methods to the extraction of useful components from Zostera marina was investigated. For the increase of the extraction yield of caffeic acid and rosmarinic acid from Zostera marina, ionic liquids and DES were used as additives in the extraction solvent. The optimum extraction conditions were found: dipping extraction, methanol as extraction solvent, 0.005 g of freeze-dried material powder, 5 mL methanol, 30 min and 0.5 g of DES-3 ($Et_4NCl$ and phenol) as additive. As a result, 0.19 mg/g of caffeic acid and 8.48 mg/g of rosmarinic acid were obtained. This method is simple and sensitive, and has been applied successfully to determine the component of caffeic acid and rosmarinic acid in Zostera marina and these results indicate that DES were used as additives is more suitable than traditional extraction for the extraction of useful components from Zostera marina.

• Journal of Environmental Science International
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• v.28 no.11
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• pp.971-981
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• 2019

This study evaluated the photocatalytic oxidation efficiency of volatile organic compounds by $Cu_2O-TiO_2$ under visible-light irradiation. $Cu_2O-TiO_2$ was synthesized by an ultrasonic-assisted method. The XRD result indicated successful p-n type photocatalysts. However, no diffraction peaks belonging to $TiO_2$ were observed for the $Cu_2O-TiO_2$. The Uv-vis spectra result revealed that the synthesized $Cu_2O-TiO_2$ can be activated under visible-light irradiation. The FE-TEM/EDS result showed the formation of synthesized nanocomposites in the commercial P25 $TiO_2$, the undoped $TiO_2$, and $Cu_2O-TiO_2$ and componential analysis in the undoped $TiO_2$ and $Cu_2O-TiO_2$. The photocatalytic oxidation efficiencies of benzene, toluene, ethylbenzene, and o-xylene with $Cu_2O-TiO_2$ were higher than those of P25 $TiO_2$ and undoped $TiO_2$. These results indicate that the prepared $Cu_2O-TiO_2$ photocatalyst can be applied effectively to control gaseous BTEX.

• Journal of Environmental Science International
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• v.27 no.11
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• pp.967-974
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• 2018

In this study, we evaluated the photocatalytic oxidation efficiency of aromatic volatile hydrocarbons by using $WO_3$-doped $TiO_2$ nanotubes (WTNTs) under visible-light irradiation. One-dimensional WTNTs were synthesized by ultrasonic-assisted hydrothermal method and impregnation. XRD analysis revealed successful incorporation of $WO_3$ into $TiO_2$ nanotube (TNT) structures. UV-Vis spectra exhibited that the synthesized WTNT samples can be activated under visible light irradiation. FE-SEM and TEM images showed the one-dimensional structure of the prepared TNTs and WTNTs. The photocatalytic oxidation efficiencies of toluene, ethylbenzene, and o-xylene were higher using WTNT samples than undoped TNT. These results were explained based on the charge separation ability, adsorption capability, and light absorption of the sample photocatalysts. Among the different light sources, light-emitting-diodes (LEDs) are more highly energy-efficient than 8-W daylight used for the photocatalytic oxidation of toluene, ethylbenzene, and o-xylene, though the photocatalytic oxidation efficiency is higher for 8-W daylight.

• Clean Technology
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• v.16 no.2
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• pp.80-87
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• 2010

In this study, micro- and submicron particles of itraconazole, a poorly water-soluble antifungal drug, were prepared for improving its aqueous solubility using an ultrasound-assisted supercritical fluid technique, called SAS-EM. The SAS-EM process used in our experiments was different from the conventional SAS-EM in that the ultrasound was applied directly to the spray nozzle. The effect of the ultrasonic power, temperature, and solvent on the formation of itraconazole particles were investigated. Smaller particles were obtained through our SAS-EM process compared with the ASES process, and the mean particle size decreased as the ultrasonic power increased. Our experimental results confirmed that the ultrasound-assisted supercritical fluid process is an efficient method for producing ultrafine particles.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.2
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• pp.38-43
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• 2007

This paper describes ultrasonically assisted grinding used to obtain a glossy surface quickly and precisely. High-quality surfaces are required for plastic injection molding dies used in the production of plastic parts such as dials for cellular phones. Traditionally, in order to finish the dies, manual polishing by a skilled worker has been required after the machining processes, such as electro discharge machining (EDM), which leaves an affected layer, and milling, which leaves tooling marks. However, manual polishing causes detrimental geometrical deviations of the die and consumes several days to finish a die surface. Therefore, a machining process for finishing dies without manual polishing to improve the surface roughness and form accuracy would be extremely valuable. In this study, a 3D positioning machine equipped with an ultrasonic spindle was used to conduct grinding experiments. An electroplated diamond tool was used for these experiments. Generally, diamond tools cannot grind steel because of excessive wear as a result of carbon atoms diffusing into bulk steel and chips. However, ultrasonically assisted grinding can achieve a fine surface (roughness Rz of $0.4{\mu}m$) on die steel without severe tool wear. The final aim of this study is to realize mirror surface grinding for injection molding dies without manual polishing. To do this, it is necessary to fabricate an electroplated diamond tool with high form accuracy and low run-out. This paper describes a tool-making method for high precision grinding and the grinding performance of a self-electroplated tool. The ground surface textures, tool performance and tool life were investigated A ground surface roughness Rz of 0.14 um was achieved Our results show that the spindle speed, feed rate and cross feed affected the surface texture. One tool could finish $5000mm^2$ of die steel surface without any deterioration of the ground surface roughness.