• Journal of Korean Society of Water and Wastewater
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• v.33 no.3
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• pp.191-204
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• 2019

The 20-kHz ultrasonic irradiation was applied to investigate bacterial inactivation and antibiotic susceptibility changes over time. Applied intensities of ultrasound power were varied at 27.7 W and 39.1 W by changing the amplitude 20 to 40 to three bacteria species (Escherichia coli, Enterococcus faecalis, and Staphylococcus aureus). By 15-min irradiation, E. coli, a gram-negative bacterium, showed 1.2- to 1.6-log removals, while the gram-positive bacteria, Enterococcus faecalis and Staphylococcus aureus, showed below 0.5-log removal efficiencies. Antibiotic susceptibility of penicillin-family showed a dramatic increase at E. coli, but for other antibiotic families showed no significant changes in susceptibility. Gram-positive bacteria showed no significant differences in their antibiotic susceptibilities after ultrasound irradiation. Bacterial re-survival and antibiotic susceptibility changes were measured by incubating the ultrasound-irradiated samples. After 24-hour incubation, it was found that all of three bacteria were repropagated to the 2- to 3-log greater than the initial points, and antibiotic inhibition zones were reduced compared to ones of the initial points, meaning that antibiotic resistances were also recovered. Pearson correlations between bacterial inactivation and antibiotic susceptibility showed negative relation for gram-negative bacteria, E. coli., and no significant relations between bacterial re-survival and its inhibition zone. As a preliminary study, further researches are necessary to find practical and effective conditions to achieve bacteria inactivation.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1263-1270
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• 2021

Recently, in the food culture life, the trend of consumers cooking is changing, and the use rate of induction cookware is increasing. Therefore, in this study, we propose the development of a functional auxiliary device to improve the safety of induction cookware to improve the convenience of cooking according to the increase in the cooking population. The proposed device is linked with IoT through the app. Through the app, the device can control the induction heating power adjustment and time reservation. In addition, an ultrasonic sensor is used to prevent the container from overflowing during cooking, and the user can safely use induction through the fine dust sensor. The implemented device conducts research assuming the actual cooking situation. Finally, it was confirmed that the user's fatigue was reduced during cooking through the device and the user's safety was improved in emergency situations such as overcooking or overflowing of water.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.81-85
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• 2022

Mist-CVD is known to have advantages of low cost and high productivity method since the precursor solution is misting with an ultrasonic generator and reacted on the substrate under vacuum-free conditions of atmospheric pressure. However, since the deposition distribution is not uniform, various efforts have been made to derive optimal conditions by changing the angle of the substrate and the position of the outlet to improve the result of the preceding study. Therefore, in this study, a deposition distribution uniformity model was derived through the shape and position of the substrate support and the conditions of inlet flow rate using the particle tracking method of computational fluid dynamics (CFD). The results of analysis were compared with the previous studies through experiment. It was confirmed that the rate of deposition area was improved from 38.7% to 100%, and the rate of deposition uniformity was 79.07% which was higher than the predicted result of simulation. Particle tracking method can reduce trial and error in experiments and can be considered as a reliable prediction method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1874-1881
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• 2021

Black ice, which occurs mainly on the road, vehicle traffic bridges and tunnel entrances due to the sub-zero temperature due to the slip of the road due to heavy snow, is not recognized because the image of asphalt is transmitted in the driver's view, so the vehicle loses braking power because it causes serious loss of life and property. In this paper, we propose a method to identify the black ice by using infrared camera and to identify the road condition by using deep learning to compensate for the disadvantages of existing black ice detection methods (artificial satellite imaging, checking the pattern of slip by ultrasonic reception, measuring the temperature of the road surface, and checking the difference in friction force of the tire during vehicle driving) and to reduce the size of the sensor to detect black ice.

• Analytical Science and Technology
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• v.21 no.3
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• pp.159-166
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• 2008

In this study, the characteristics of emulsified fuel and engine emissions were studied. Emulsified fuel which composed of water and diesel was manufactured by using homogenizer and ultrasonic generator. Engine emissions were studied whit engine dinamometer. In emulsified fuel, density and viscosity were increased with increasing water contents, but viscosity was decreased over 60% of water in emulsion fuel. The emulsion type of W/O changed to that of O/W over 60% of water in emulsion fuel. In the results of engine dinamometer test, NOx concentration and smoke density were reduced with increasing water contents in emulsified fuel but reciprocal in the case of THC, CO. Temperature and power were reduced with increasing water contents in emulsion fuel. In conclusion, it seemed that using emulsified fuel for diesel engine was effective for reducing NOx concentration and smoke density.

• Journal of Korean Medicine Rehabilitation
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• v.33 no.4
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• pp.167-184
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• 2023

Objectives This study was designed to assess the effectiveness of ultrasound therapy at the ST11 for regulation of sympathetic hyperactivity. Methods Forty healthy adult subjects were assigned to experimental group and control group. After taking mental stress, ultrasound therapy was applied at the ST11 in experimental group and sham-ultrasound therapy was applied in control group. The evaluation of sympathetic activity was measured by blood pressure, pulse rate, and heart rate variability at 3 times (Time 1: before the stress stimulation, Time 2: after the stress stimulation, Time 3: after the intervention). The primary end point was consisted of normalized (norm) low frequency (LF)/high frequency (HF) ratio, LF (norm), HF (norm). The secondary end point was consisted of systolic blood pressure, diastolic blood pressure, pulse rate, mean heart rate, standard deviation of NN intervals, root mean square of the successive differences, total power (log). Results After the stress stimulation, all subjects showed sympathetic hyperactivity. After the intervention, the experimental group showed lower sympathetic activity than the control group. Comparing the Time 3 and Time 1, the experimental group showed no significantly differences in sympathetic activity while the control group showed higher sympathetic activity in Time 3 than Time 1. Comparing the Time 3 and Time 2, the experimental group showed lower sympathetic activity in Time 3 than Time 2 while the control group showed higher sympathetic activity in Time 3 than Time 2. Conclusions We suggest that the ultrasound therapy at ST11 can decrease sympathetic activity in sympathetic hyperactivity condition.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.2
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• pp.155-162
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• 2023

In nuclear power plants, the flow rate information is a major indicator of the performance of rotating equipment such as pumps, and is a very important one required for facility operation and maintenance. To measure a flow rate, various types of methods have been developed and used. Among them, the differential pressure type using orifice and the direct doppler type using ultrasonic waves are the most commonly used. However, these flow rate measurement methods have limitations in installation, conditions and status of the measuring part, etc. To solve this problem, we have studied a new technique for measuring flow rate from scratch. In this paper, we have devised a technique to estimate the flow rate using an average moving velocity of large-scale eddy in turbulence that occurs in the piping flow field. The velocity of the large-scale eddy can be measured using the pressure fluctuation signals on the inner surface of the pipe. To estimate the flow rate, at first a cross-correlation function is applied to the two pressure fluctuation signals located at different positions in the down stream for calculating the time delay between the moving eddies. In order to validate the proposed flow rate estimation method, CFD analyses for the internal turbulence flow in pipe are conducted with a fixed flow condition, where the pressure fluctuation signals on the pipe inner surface are simulated. And then the average flow velocity of the large scale eddy is to be estimated. The estimated flow velocity is turned out to be similar to the fixed (known) flow rate.

• Steel and Composite Structures
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• v.51 no.2
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• pp.185-202
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• 2024

In this research paper, and for the first time, wave propagations in sigmoidal imperfect functionally graded material plates are investigated using a simplified quasi-three-dimensionally higher shear deformation theory (Quasi-3D HSDTs). By employing an indeterminate integral for the transverse displacement in the shear components, the number of unknowns and governing equations in the current theory is reduced, thereby simplifying its application. Consequently, the present theories exhibit five fewer unknown variables compared to other Quasi-3D theories documented in the literature, eliminating the need for any correction coefficients as seen in the first shear deformation theory. The material properties of the functionally graded plates smoothly vary across the cross-section according to a sigmoid power law. The plates are considered imperfect, indicating a pore distribution throughout their thickness. The distribution of porosities is categorized into two types: even or uneven, with linear (L)-Type, exponential (E)-Type, logarithmic (Log)-Type, and Sinus (S)-Type distributions. The current quasi-3D shear deformation theories are applied to formulate governing equations for determining wave frequencies, and phase velocities are derived using Hamilton's principle. Dispersion relations are assumed as an analytical solution, and they are applied to obtain wave frequencies and phase velocities. A comprehensive parametric study is conducted to elucidate the influences of wavenumber, volume fraction, thickness ratio, and types of porosity distributions on wave propagation and phase velocities of the S-FGM plate. The findings of this investigation hold potential utility for studying and designing techniques for ultrasonic inspection and structural health monitoring.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.10
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• pp.664-670
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• 2012

A study on the in situ regeneration effect of commercial deactivated SCR catalyst which had been exposed to the off gas from the heavy oil fired power plant for a long time was carried out in a simulated in situ conditions by washing with distilled water and various acid solutions in a short time. The catalytic performance test of the regenerated SCR catalysts was carried out in the micro reactor with simulated off gas of the heavy oil fired power plant and all prepared catalysts were characterized by BET, Porosimeter, EDX (Energy Dispersive X-ray spectrometer) and ICP (Inductively Coupled Plasma) to investigate correlations between catalytic activity and surface characteristics of them. The characterization results of the regenerated catalysts showed that the specific surface area was restored 95% more than that of fresh catalyst. Under this study, the activity of the regenerated catalysts with acid solution (3~6 M) without using ultrasonic wave in a simulated in situ conditions was restored 90% more than that of the fresh catalyst. It was found that improved activity of regenerated catalyst was caused by removing the deactivating materials from the surface of the deactivated SCR catalyst through acid washing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.11
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• pp.1709-1715
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• 2014

The objective of this study was to examine the antioxidant activities of extracts from Mori ramulus using different extraction methods (HE, hot water extraction; EE, 50% ethanol extraction; UE, ultrasonic extraction; PE, pressured extraction). The extraction yield of PE (3.07%) was higher than that of UE (1.43%), EE (1.18%), and HE (1.07%). The total phenolic and flavonoid contents of EE were 334.66 mg/g, and 35.64 mg/g, respectively. The oxygen radical absorbance capacity (ORAC) of EE ($3,483.37{\mu}M/g$ FW) was higher than those of HE ($2,687.52{\mu}M/g$ FW), UE ($2,300.45{\mu}M/g$ FW), and PE ($2,117.62{\mu}M/g$ FW). The DPPH and ABTS radical scavenging activities of EE at $1,000{\mu}g/mL$ were 65.84%, and 97.52%, respectively. The superoxide radical scavenging activity of EE was 67.77~98.74% ($100{\sim}500{\mu}g/mL$) higher than those of other extracts. The ferric reducing antioxidant power and reducing power of EE were $189.00{\sim}974.80{\mu}M$, and 0.12~0.82, respectively. The tyrosinase inhibitory activity of EE (23.25~67.20%) improved with an increase treatment concentration. The antioxidant and tyrosinase inhibitory activities of EE were significantly higher than those of other extracts. In conclusion, we provided experimental evidence that extracts from Mori ramulus have potential as functional materials.