• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.2
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• pp.183-202
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• 2019

For design and performance assessment of a high-level radioactive waste (HLW) disposal system, it is necessary to understand the characteristics of coupled thermo-hydro-mechanical (THM) behavior. However, in previous studies for the Korean Reference HLW Disposal System (KRS), thermal analysis was performed to determine the spacing of disposal tunnels and interval of disposition holes without consideration of the coupled THM behavior. Therefore, in this study, TOUGH2-MP/FLAC3D is used to conduct THM modeling for performance assessment of the Korean Reference HLW Disposal System (KRS). The peak temperature remains below the temperature limit of $100^{\circ}C$ for the whole period. A rapid rise of temperature caused by decay heat occurs in the early years, and then temperature begins to decrease as decay heat from the waste decreases. The peak temperature at the bentonite buffer is around $96.2^{\circ}C$ after about 3 years, and peak temperature at the rockmass is $68.2^{\circ}C$ after about 17 years. Saturation of the bentonite block near the canister decreases in the early stage, because water evaporation occurs owing to temperature increase. Then, saturation of the bentonite buffer and backfill increases because of water intake from the rockmass, and bentonite buffer and backfill are fully saturated after about 266 years. The stress is calculated to investigate the effect of thermal stress and swelling pressure on the mechanical behavior of the rockmass. The calculated stress is compared to a spalling criterion and the Mohr-Coulumb criterion for investigation of potential failure. The stress at the rockmass remains below the spalling strength and Mohr-Coulumb criterion for the whole period. The methodology of using the TOUGH2-MP/FLAC3D simulator can be applied to predict the long-term behavior of the KRS under various conditions; these methods will be useful for the design and performance assessment of alternative concepts such as multi-layer and multi-canister concepts for geological spent fuel repositories.

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.339-348
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• 2019

The purpose of this study was to investigate the effect of carotid artery ultrasound Respectively. The carotid intima-media thickness is known to have a significant correlation with cardiovascular disease and cerebrovascular disease. We investigated the relationship between carotid intima - media thickness, body mass index, waist circumference, the blood lipid value, fasting blood glucose, glycated hemoglobin, and blood pressure using carotid artery ultrasound. The carotid artery ultrasound was considered to be abnormality of IMT thickness over 0.8 mm and the presence or absence of atherosclerotic plaque was evaluated. Serological tests were used to compare the geologic value, fasting blood glucose level, and glycated hemoglobin. As a result, waist circumference (=.022), low density cholesterol (=.004), fasting blood glucose level (.019), and glycemic index (.002) were analyzed as predictors of atherosclerosis. In the ROC curve analysis, sensitivity was 87.80% (95% CI: 73.8-95.9), specificity was 41.67% (95% CI: 30.2-53.9), sensitivity was 78.05% (95% CI: 62.4-89.4) in low density lipoprotein, Specificity was 50.00% (95% CI: 38.0-62.0), sensitivity was 73.11% (95% CI: 57.1-85.8), specificity was 61.11 (95% CI: 48.9-72.4) and sensitivity was 82.93%-91.8) and a specificity of 43.06% (31.4-55.3). In logistic regression analysis, the risk of atherosclerosis was 0.248 times at waist circumference (WC)> 76 cm, 3.475 times at low-density lipoprotein (LDL-C) ${\geq}124mg/dL$, 0.618 at HbA1c> 5.4% It appeared as a times. We suggest that prospective study of carotid artery ultrasound should be performed for the effective prevention of cardiovascular diseases.

• Clean Technology
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• v.25 no.3
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• pp.245-255
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• 2019

Pressurized oxy-fuel combustion is a promising technology for $CO_2$ capture with a benefit of improving power plant efficiency compared with atmospheric oxy-fuel combustion. Prior to $CO_2$ compression in this process, a flue gas condenser (FGC) is used to remove $H_2O$ while recovering the latent heat. At the same time, the FGC has a potential for high-efficiency removal of $SO_x$ and $NO_x$ by exploiting their good solubility in water. In this study, experiments were carried out in a lab-scale, direct contact FGC under different pressures varying between 1 and 20 bar to evaluate the removal efficiency of $SO_2$ and $NO_x$ for individual gases and their mixture. In the tests for individual gases, 20% and 76% of $NO_x$ was removed at 1 bar and 10 bar, respectively. Even higher removal efficiencies were achieved for $SO_2$, and also these were maintained for longer as the pressure increased. In the tests for $SO_2$ and $NO_x$ mixture, the removal efficiency of $NO_x$ increased from 13% at 1 bar to 56% at 20 bar because of higher solubility at elevated pressures. $SO_2$ in the mixture was initially dissolved almost completely and then increased by 1,219 ppm at 1 bar and by 165 ppm at 20 bar. Overall, the removal efficiency of $SO_2$ and $NO_x$ was increased at elevated pressures, but it was lower in the mixture compared with individual gases at identical conditions because of a lower pH and associated chemical reactions in water.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.405-411
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• 2019

In this study, tensile tests were carried out on materials (A516-60, A283-C, A285-C, and SB410) for structural and pressure vessels at temperatures of $20^{\circ}C$, $-20^{\circ}C$, and $-40^{\circ}C$, and the changes in the mechanical properties were analyzed. Compared to the results at $20^{\circ}C$, the average yield stress increased by 6.4% and 7.5% at $-20^{\circ}C$ and $-40^{\circ}C$ for A516-60, while the average tensile stress increased by 1.3% and 4.1%, respectively. The average elongation decreased by 4.7% and 20.4% at these temperatures. In the case of A283-C, the average yield stress increased 8.8% and 9.8%, the average tensile stress increased by 4.1% and 5.9%, and the average elongation rate decreased by 7.4% and 9.9% at $-20^{\circ}C$ and $-40^{\circ}C$, respectively. For A285-C, the average yield stress increased by 1.8% and 8.6%, and the average tensile stress increased by 2.6% and 5.3%, respectively, but there was little change in the average elongation. Finally, for SB410, the average yield stress increased by 7.1% and 11.8%, the average tensile stress increased by 4.3% and 5.5%, but the average elongation rate decreased by 8.7% and 13.5%, respectively.

• Phonetics and Speech Sciences
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• v.11 no.3
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• pp.69-76
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• 2019

This study aimed to investigate the effects of vocal aerobic treatment (VAT) on the improvement of voice in patients with voice disorders. Twenty patients (13 males, 7 females) were diagnosed with voice disorders on the basis of videostroboscopy and voice evaluations. Acoustic evaluation was performed with the Multidimensional voice program (MDVP) and Voice Range Profile (VRP) of Computerized Speech Lab (CSL), and aerodynamic evaluation with PAS (Phonatory Aerodynamic System). The changes in F0, Jitter, Shimmer, and NHR before and after treatment were measured by MDVP. F0 range and Energy range were measured with VRP before and after treatment, and the changes in Expiratory Volume (FVC), Phonation Time (PHOT), Mean Expiratory Airflow (MEAF), Mean Peak Air Pressure (MPAP), and Aerodynamic Efficiency (AEFF) with PAS. Videostroboscopy was performed to evaluate the regularity, symmetry, mucosal wave, and amplitude changes of both vocal cords before and after treatment. Voice therapy was performed once a week for each patient using the VAT program in a holistic voice therapy approach. The average number of treatments per patient was 6.5. In the MDVP, Jitter, Shimmer, and NHR showed statistically significant decreases (p < .001, p < .01, p < .05). VRP results showed that Hz and semitones in the frequency range improved significantly after treatment (p < .01, p < .05), as did PAS, FVC, and PHOT (p < .01, p < .001). The results for videostroboscopy, functional voice disorder, laryngopharyngeal reflux, and benign vocal fold lesions were normal. Thus, the VAT program was found to be effective in improving the acoustic and aerodynamic aspects of the voice of patients with voice disorders. In future studies, the effect of VAT on the same group of voice disorders should be studied. It is also necessary to investigate subjective voice improvement and objective voice improvement. Furthermore, it is necessary to examine the effects of VAT in professional voice users.

• The Journal of the Petrological Society of Korea
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• v.28 no.3
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• pp.157-169
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• 2019

Pseudotachylytes, produced by frictional heating during seismic slip, provide information that is critical to understanding the physics of earthquakes. We report the results of occurrence, structural characteristics, scanning electron microscopic observation and geochemical analysis of pseudotachylytes, which is presumed to have formed after the Late Cretaceous in outcrops of the Paleoproterozoic granitic gneiss on the Bulil waterfall of the Jirisan area, Yeongnam massif, Korea. Fault rocks, which are the products of brittle deformation under the same shear stress regime in the study area, are classified as pseudotachylyte and foliated cataclasite. The occurrences of pseudotachylyte identified on the basis of thickness and morphology are fault vein-type and injection vein-type pseudotachylyte. A number of fault vein-type pseudotachylytes occur as thin (as thick as 2 cm) layers generated on the fault plane, and are cutting general foliation and sheared foliation developed in granitic gneiss. Smaller injection vein-type pseudotachylytes are found along the fault vein-type pseudotachylytes, and appear in a variety of shapes based on field occurrence and vein geometry. At a first glance fault vein-type seudotachylyte looks like a mafic vein, but it has a chemical composition almost identical to the wall rock of granitic gneiss. Also, it has many subrounded clasts which consist predominantly of quartz, feldspar, biotite and secondary minerals including clay minerals, calcite and glassy materials. Embayed clasts, phenocryst with reaction rim, oxide droplets, amygdules, and flow structures are also observed. All of these evidences indicate the pseudotachylyte formed due to frictional melting of the wall rock minerals during fault slip related to strong seismic faulting events in the shallow depth of low temperature-low pressure. Further studies will be conducted to determine the age and mechanical aspect of the pseudotachylyte formation.

• Journal of Nutrition and Health
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• v.52 no.5
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• pp.435-448
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• 2019

Purpose: This study examined the changes in the nutrient intake and the prevalences of obesity and metabolic syndrome according to the eating alone behavior in middle-aged men and women. Methods: The data from the 2013 ~ 2017 Korean National Health and Nutrition Examination Survey were analyzed. A total of 7,728 adults (3,404 male, 4,324 female) aged 40 ~ 64 years old were included. The subjects were classified into three groups according to the number of times eating alone per day (0, 1 ~ 2, and 3 times/day). Dietary data were collected by a 1-day 24-h recall. The nutrient intakes were compared among the three groups. Survey logistic regression analyses were conducted to examine the association of the eating alone behavior with obesity and metabolic syndrome, adjusting for the related confounding variables. Results: In men, eating alone was associated significantly with a lower intake of potassium (p-for-trend = 0.048) and lower intake of calories from protein (p-for-trend = 0.04). In women, the proportion of subjects consuming energy less than 75% of the estimated energy requirement (p = 0.001) and less than the estimated adequate requirement of riboflavin (p < 0.001) differed significantly according to the eating alone behavior. The eating alone behavior was positively associated with an increased risk of developing metabolic syndrome (p-for-trend = 0.033), increased blood pressure (p-for-trend < 0.001), and increased waist circumference (p-for-trend = 0.004). On the other hand, in women, however, the eating alone behavior was associated with a decreased risks of developing obesity (p-for-trend = 0.02). No association was found between the eating alone behavior and the risk of metabolic syndrome in women. Conclusion: These results suggest that the eating alone behavior is a risk factor for the development of metabolic syndrome in middle-aged Korean men.

• Korean Journal of Remote Sensing
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• v.35 no.3
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• pp.415-431
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• 2019

The satellite-viewed cloudiness, a ratio of cloudy pixels to total pixels ($C_{sat,\;prev}$), inevitably differs from the "ground-viewed" cloudiness ($C_{grd}$) due to different viewpoints. Here we develop an algorithm to retrieve the satellite-viewed, but adjusted cloudiness to $C_{grd} (C_{sat,\;adj})$. The key process of the algorithm is to convert the cloudiness projected on the plane surface into the cloudiness on the celestial hemisphere from the observer. For this conversion, the supplementary satellite retrievals such as cloud detection and cloud top pressure are used as they provide locations of cloudy pixels and cloud base height information, respectively. The algorithm is tested for Himawari-8 level 1B data. The $C_{sat,\;adj}$ and $C_{sat,\;prev}$ are retrieved and validated with $C_{grd}$ of SYNOP station over Korea (22 stations) and China (724 stations) during only daytime for the first seven days of every month from July 2016 to June 2017. As results, the mean error of $C_{sat,\;adj}$ (0.61) is less that than that of $C_{sat,\;prev}$ (1.01). The percent of detection for 'Cloudy' scenario of $C_{sat,\;adj}$ (73%) is higher than that of $C_{sat,\;prev}$ (60%) The percent of correction, the accuracy, of $C_{sat,\;adj}$ is 61%, while that of $C_{sat,\;prev}$ is 55% for all seasons. For the December-January-February period when cloudy pixels are readily overestimated, the proportion of correction of $C_{sat,\;adj$ is 60%, while that of $C_{sat,\;prev}$ is 56%. Therefore, we conclude that the present algorithm can effectively get the satellite cloudiness near to the ground-viewed cloudiness.

• Economic and Environmental Geology
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• v.54 no.1
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• pp.105-115
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• 2021

The geological CO2 sequestration in underground geological formation such as deep saline aquifers and depleted hydrocarbon reservoirs is one of the most promising options for reducing the atmospheric CO2 emissions. The process in geological CO2 sequestration involves injection of supercritical CO2 (scCO2) into porous media saturated with pore water and initiates CO2 flooding with immiscible displacement. The CO2 migration and distribution, and, consequently, the displacement efficiency is governed by the interaction of fluids. Especially, the viscous force and capillary force are controlled by geological formation conditions and injection conditions. This study aimed to estimate the effects of surfactant on interfacial tension between the immiscible fluids, scCO2 and porewater, under high pressure and high temperature conditions by using a pair of proxy fluids under standard conditions through pendant drop method. It also aimed to observe migration and distribution patterns of the immiscible fluids and estimate the effects of surfactant concentrations on the displacement efficiency of scCO2. Micromodel experiments were conducted by applying n-hexane and deionized water as proxy fluids for scCO2 and porewater. In order to quantitatively analyze the immiscible displacement phenomena by n-hexane injection in pore network, the images of migration and distribution pattern of the two fluids are acquired through a imaging system. The experimental results revealed that the addition of surfactants sharply reduces the interfacial tension between hexane and deionized water at low concentrations and approaches a constant value as the concentration increases. Also it was found that, by directly affecting the flow path of the flooding fluid at the pore scale in the porous medium, the surfactant showed the identical effect on the displacement efficiency of n-hexane at equilibrium state. The experimental observation results could provide important fundamental information on immiscible displacement of fluids in porous media and suggest the potential to improve the displacement efficiency of scCO2 by using surfactants.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.196-202
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• 2011

In this paper, a series of alkyl succinic acid esters for base oil were synthesized by condensation reaction of succinic anhydride and fatty alcohol. The structures of the synthesized esters were confirmed by $^1H-NMR$, FT-IR spectrum and GC analysis. Basic properties of esters such as kinematic viscosity (KV), refractive index (RI), total acid number (TAN) and pour points were measured and lubricating properties such as SRV wear scar diameter (SRV WSD), fraction coefficient (COF) and 4-ball wear (4-ball WSD) were also evaluated. As the results of basic properties, KV, RI and pour point of synthetic esters increased as the carbon chain of the esters increased. Measurement value of total acid number (TAN) was indicated between 0.2~4 mgKOH/g, and that metal working fluids and pressure working oils are acceptable to use as base oil. Also, lubricating properties of the esters showed as follows: 0.391~0.689 mm of SRV WSD, 0.110~0.138 of SRV COF and 0.49~0.55 mm of 4-ball WSD depended on the structure of the esters. In a comparison on the lubrication capacity of the SRV test based on polyester TMPTO, SRV WSD result showed that a better performance caused by the alkyl group. On the other hand, SRV COF test was not influenced of the alkyl group which the capacity of the lubricant was sightly diminished than the comparison material, regardless of the alkyl group.