• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.135-144
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• 2024

Ultrasonography examination has limitations in quantifying hepatic fat quantification. Therefore, this study aimed to experimentally demonstrate whether changes in signal attenuation during ultrasound imaging can be quantified using simulated hepatic phantoms to assess hepatic fat content. Additionally, we aimed to evaluate the potential of ultrasound imaging for diagnosing hepatic fatty liver by analyzing the relationship between hepatic fat content and signal intensity in ultrasound images. In this study, we developed a total of five stimulated hepatic phantoms by homogeneously mixing water and oil. We confirmed the fat content of the phantoms using magnetic resonance imaging (MRI) and ultrasound imaging, and measured signal intensity according to distance in ultrasound images to analyze the correlation and mean comparison between fat content and signal intensity. We observed that as the fat content increased, the ultrasound penetration intensity decreased, confirming the potential for quantifying hepatic fat content using ultrasound. Additionally, the analysis of the correlation between the measured fat content using MRI and the signal intensity measured in ultrasound images showed a high correlation. Statistical analysis in our study confirmed that as the fat content increased, the slope representing signal during ultrasound imaging (US-GRE) decreased. In this study, it was statistically confirmed that the US-GRE value of ultrasound images gradually decreases as the fat content increases, and it is believed that US-GRE can serve as a biomarker expressing fatty liver content.

• Journal of the Korean GEO-environmental Society
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• v.19 no.11
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• pp.15-22
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• 2018

The main objective of this study was to analyse heavy metals in sediments obtained from Gwangan bridge and to evaluate pollution intensity of the sites. To evaluate pollution intensity of the sites, we used enrichment factor (EF), geoaccumulation index, potential ecological risk factor (PERF), and mean PEL quotient. Pollution intensities of these sites were evaluated by above methods, and we found most dangerous heavy metal and polluted sites. All sites showed non polluted or low risk for the heavy metals such as Cr, Cu, Ni, Pb, and Zn, but all sites were categorized as minor enrichment for Cd. G4 was evaluated as moderately polluted by Cd ($I_{geo}$) but other sites were unpolluted by heavy metals. In summary, Cd was found to be higher concentrations for all sites. For G4 and G5 sites, Pb and Zn in addition to Cd were higher than other sites.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.5
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• pp.1262-1269
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• 2008

Low intensity pulsed ultrasound(LIPUS) is known to accelerate bone regeneration, but the precise cellular signaling mechanism is still unclear. The purpose if this study was to determine the effect of LIPUS on the signaling mechanism of rat chondrocyte. In the explant culture condition, there was inhibition effect of 1 $W/cm^2$ intensity LIPUS on chondrocytes proliferation but chondrocytes proliferation was increased at 0.25 $W/cm^2$ intensity. In addition, western blot analysis of MAPKs showed that LIPUS increased ERK1/2 activity from the 10 min treatment of LIPUS. Hydrogen peroxide($H_2O_2$), resulted in a time- and dose-dependent cell proliferation, which was largely attributed to apoptosis. $H_2O_2$ treatment caused marked sustained nucleus condensation in Hoechst stain. LIPUS and $H_2O_2$ activates phosphorylation of p-ERK1/2 and PD 98059($10^{-5}M$) blocked the effect of LIPUS and $H_2O_2$. Moreover, the synergistic phosphorylation of p44/42 MAPK by $H_2O_2$, LIPUS was selectively inhibited by PD 98059, ERK1/2 inhibitor. In order to determine whether the increase in cell proliferation caused by $H_2O_2$ and LIPUS could be explained by changes in the level of the prostaglandin $E_2$. Our study demonstrated that LIPUS stimulate the cell proliferation via activated phosphorylation of ERK1/2 in condrocyte. LIPUS has anabolic effects on rat cartilage in explant cultures, indicating a potential important method for the treatment of osteoarthritic cartilarge.

• Safety and Health at Work
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• v.12 no.4
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• pp.439-444
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• 2021

Background: In a previous study, we estimated exposure prevalence and the number of workers exposed to carcinogens by industry in Korea. The present study aimed to evaluate the optimal exposure intensity indicators of airborne lead exposure by comparing to blood lead measurements for the future development of the carcinogen exposure intensity database. Methods: Data concerning airborne lead measurements and blood lead levels were collected from nationwide occupational exposure databases, compiled between 2015 and 2016. Summary statistics, including the arithmetic mean (AM), geometric mean (GM), and 95th percentile level (X95) were calculated by industry both for airborne lead and blood lead measurements. Since many measurements were below the limits of detection (LODs), the simple replacement with half of the LOD and maximum likelihood estimation (MLE) methods were used for statistical analysis. For examining the optimal exposure indicator of airborne lead exposure, blood lead levels were used as reference data for subsequent rank correlation analyses. Results: A total of 19,637 airborne lead measurements and 32,848 blood lead measurements were used. In general, simple replacement showed a higher correlation than MLE. The results showed that AM and X95 using simple replacement could be used as optimal exposure intensity indicators, while X95 showed better correlations than AM in industries with 20 or more measurements. Conclusion: Our results showed that AM or X95 could be potential candidates for exposure intensity indicators in the Korean carcinogen exposure database. Especially, X95 is an optimal indicator where there are enough measurements to compute X95 values.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.614-620
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• 2019

Microalgae have been explored as potential host species for biofuel production. Environmental factors affect algal growth and cellular composition. The effects of several key environmental factors, such as temperature, light, and pH of the medium on the growth and biochemical composition of Scenedesmus obliquus were investigated in this study. The highest growth rate of microalgae was observed at an optimal temperature of 25℃, 150 μmol/(m²·s) light intensity, and pH 10.0. The biochemical composition analysis revealed that the carbohydrate content decreased at lower (20℃) or higher temperature (35℃), whereas the protein and lipid contents increase at these temperatures. The fluctuation of light intensity significantly affected the contents of protein, carbohydrate, and lipid. The protein levels varied greatly when the pH of the medium was below 7.0. The carbohydrate and lipid contents significantly increased at pH above 7.0.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.93-97
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• 2003

The crystallization behavior of amorphous silicon is affected by direction and intensity of electric field in FALC（Field-Aided Lateral Crystallization). Electric field was calculated in a simplified model using conductivity data of Mo, a-Si, $SiO_2$and boundary conditions for electric potential at the electrodes. The magnitude of electric field intensity in each corner of cathode was much larger than that in the center of patterns, and the electric field direction was 50~60 degree outside to cathode. And electric field intensity at a relatively small pattern was larger than that of a large pattern.

• Journal of Environmental Science International
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• v.22 no.3
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• pp.319-329
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• 2013

In this study, the cause of rapid intensity change of typhoon Nakri(0208) in view of point of a trough-typhoon interaction using diagnostic methods was examined based on 6-hourly GDAPS data from 10 to 13 July, 2002. At 0000 UTC 13 July, high PV(Potential Vorticity) region moved southeastward, reaching to the western edge of the Korean peninsula and near typhoon center at surface and there shows an increasing value of EFC(Eddy Momentum Flux Convergence). Also, as the trough and typhoon approach one another at the same time, the vertical shear(850-200 hPa) increases to more than 15 m/s. Thus, it might be concluded that the trough-typhoon interaction made intensified significantly, providing the fact that typhoon Nakri(0208) underwent substantial weakening while moving northward to around Jeju island.

• Journal of Environmental Science International
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• v.21 no.4
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• pp.411-419
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• 2012

In this study, Ibuprofen (IBP) degradation by the photo catalytic process was investigated under various parameters, such as UV intensity, optimum dosage of $TiO_2$, alkalinity, temperature and pH of bulk solution. The pseudo-first order degradation rate constants were in the order of $10^{-1}$ to $10^{-4}min^{-1}$ depending on each condition. The Photocatalytic IBP degradation rate increased with an increase in the applied UV power. At high UV intensity a high rate of tri-iodide ($I_3{^-}$) ion formation was also observed. Moreover, in order to avoid the use of an excess catalyst, the optimum dosage of catalyst under the various UV intensities (30 and 40 W/L) was examined and ranged from approximately 0.1 $gL^{-1}$. The photo catalytic IBP degradation rate was changed depending on the alkalinity and temperature and pH in the aqueous solution. This study demonstrated the potential of photo catalytic IBP degradation under different conditions.

• Wind and Structures
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• v.18 no.3
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• pp.235-252
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• 2014

An effective numerical technique to calculate the reactions of a multi-spanned transmission line conductor system, under arbitrary loads varying along the spans, is developed. Such variable loads are generated by High Intensity Wind (HIW) events in the form of tornadoes and downburst. First, a semi-closed form solution is derived to obtain the displacements and the reactions at the ends of each conductor span. The solution accounts for the nonlinearity of the system and the flexibility of the insulators. Second, a numerical scheme to solve the derived closed-form solution is proposed. Two conductor systems are analyzed under loads resulting from HIW events for validation of the proposed technique. Non-linear Finite Element Analyses (FEA) are also conducted for the same two systems. The responses resulting from the technique are shown to be in a very good agreement with those resulting from the FEA, which confirms the technique accuracy. Meanwhile, the semi-closed form technique shows superior efficiency in terms of the required computational time. The saving in computational time has a great advantage in predicting the response of the conductors under HIW events, since this requires a large number of analyses to cover different potential locations and sizes of those localized events.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.5
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• pp.164-169
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• 1983

A method to control the luminous colour of a gaseous discharge tube has been investigated by using the saw-tooth wave of which rise-time was controlled by an electronic circuit. The luminous colour of a Ne - Hg lamp was changed from red to blue continuously and vice versa, and it's luminous characteristics are as follows: (a) With D.C. potentials, it showed blue colour and the relative intensity of the colour is increased first and saturated at about 17 mA as the discharge current is increased. (b) When the rise-time of the saw-tooth wave is about 10 $\mu\textrm{s}$, the red colour which is caused by Ne - excitation is dominant, and when about 200 $\mu\textrm{s}$, only the blue colour which is caused by Hg - excitation is shown. (c) With saw-tooth pulse, the relative intensity of blue is increased similarly as that with D.C. potential as the current peak of each pulse is increased, while that of red is increasing continuously and it's intensity shows about twice than blue. (d) The spectrum of red colour contains Ne - excitation lines and Hg - blue lines, but the apparent luminous colour is red because Ne - red lines are more plenty than Hg-blue lines. The spectrum of blue colour presents only Hg-blre lines.