• Polymer(Korea)
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• v.38 no.4
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• pp.471-476
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• 2014

Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blends were prepared using a high shear extruder to investigate their thermal decomposition and mechanical properties with shear rate and shear time. In this experiment, high shear rate, from 1000 to 3000 rpm, in blending process was applied for 10 to 40 sec, respectively. At high shear rate over than 2000 rpm, the initial decomposition temperature was dropped significantly compared to a compounded sample because of thermal decomposition of the blend by high shear. Consequently, high shear processing gave an important effect on the mechanical and thermal properties of the PC/ABS blend. In particular, elongation of the blend decreased significantly with shear rate.

• Biomedical Science Letters
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• v.17 no.4
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• pp.305-311
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• 2011

Heart rate recovery (HRR) immediately after a treadmill exercise test is a function of vagal reactivation. A delayed heart rate recovery is associated with an increased risk for overall cardiovascular mortality. The purpose of this study is to find out if metabolic syndrome is associated with autonomic nerve function and exercise capacity in healthy adults. We measured the treadmill exercise capacity (METs) and heart rate recovery in 119 subjects through a medical checkup at $J$ General Hospital. The metabolic syndrome was defined according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria. The value for the HRR was defined as the difference between the heart rate obtained during the peak exercise and the heart rate obtained at first minute during the recovery period. The subjects with the metabolic syndrome had significantly lower exercise duration ($9.6{\pm}1.5$ vs $8.7{\pm}1.4$), METs ($11.6{\pm}1.7$ vs $10.4{\pm}2.5$), and HRR ($37.5{\pm}14.3$ vs $27.1{\pm}8.9$). The waist circumference in subjects with the metabolic syndrome was more strongly correlated with HRR ($r$=-.517, $P$ <.001) than in normal subjects. Furthermore, delayed HRR was associated with high resting heart rate and increased waist circumference ($P$=.032, $P$ <.001, respectively). In conclusion, delayed HRR during the first minute after a treadmill exercise test was associated with the metabolic syndrome risk factors. Delayed HRR was also associated with high resting heart rate and increased waist circumference.

• Journal of Environmental Science International
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• v.27 no.8
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• pp.621-629
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• 2018

Many chemically active species such as ${\cdot}H$, ${\cdot}OH$, $O_3$, $H_2O_2$, hydrated $e^-$, as well as ultraviolet rays, are produced by Dielectric Barrier Discharge (DBD) plasma in water and are widely use to remove non-biodegradable materials and deactivate microorganisms. As the plasma gas containing chemically active species that is generated from the plasma reaction has a short lifetime and low solubility in water, increasing the dissolution rate of this gas is an important challenge. To this end, the plasma gas and water within reactor were mixed using the air-automizing nozzle, and then, water-gas mixture was injected into water. The dissolving effect of plasma gas was indirectly confirmed by measuring the RNO (N-Dimethyl-4-nitrosoaniline, indicator of the formation of OH radical) solution. The plasma system consisted of an oxygen generator, a high-voltage power supply, a plasma generator and a liquid-gas mixing reactor. Experiments were conducted to examine the effects of location of air-automizing nozzle, flow rate of plasma gas, water circulation rate, and high-voltage on RNO degradation. The experimental results showed that the RNO removal efficiency of the air-automizing nozzle is 29.8% higher than the conventional diffuser. The nozzle position from water surface was not considered to be a major factor in the design and operation of the plasma reactor. The plasma gas flow rate and water circulation rate with the highest RNO removal rate were 3.5 L/min and 1.5 L/min, respectively. The ratio of the plasma gas flow rate to the water circulation rate for obtaining an RNO removal rate of over 95% was 1.67 ~ 4.00.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.42-47
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• 2004

This study was accomplished to develope an advanced wastewater treatment process using high MLSS in anoxic tank aimed to improve nutrient removal and to reduce wasting sludge. It was operated with 4 Modes with varing solid concentration and internal recycle ratios. Mode I, II, III was operated 1.0~1.5% MLSS concentration at anoxic tank with 50% sludge recycle rate, however, each internal recycle rate were 100%, 200%, 300% and Mode IV was operated 1.5~2.0% MLSS concentration at anoxic tank with 50% sludge recycle rate and 100% internal recycle rate. The COD removal efficiency didn't show any big difference from Mode I to IV. The average COD removal rate was over than 90%. The T-N removal rate was 73%, the highest rate in all mode. The 36% of SCOD is used for the denitrification and phosphorus release in the anoxic tank. Specific denitrification rate was 3.5mg $NO_3{^-}-N/g$ Mv/hr and denitrification time was 0.7hr. As MLSS concentration is higher in anoxic tank as denitrification time would be shorter. The T-P removal rate was average 70%. The phosphorus release accomplished from the anoxic tank because the anaerobic condition was prevalent in the anoxic due to the prompt completion of denitrification. Sludge production was 0.28 kgVSS/kg $BOD_{removed}$ under the 1.5% MLSS and 17 day SRT. It is prominent result which has 40% sludge reduce comparing with traditional activate sludge system.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.187-193
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• 2015

Deleterious effects of high dose radiation exposure with high-dose-rate are unarguable, but they are still controversial in low-dose-rate. The regulator of G-protein signaling (RGS) is a negative regulator of G protein-coupled receptor (GPCR) signaling. In addition, it is reported that irradiation stress led to GPCR-mediated mitogen-activated protein kinase (MAPK) and phosphotidylinositol 3-kinase (PI3-k) signaling. The RGS mRNA expression profiles by whole body radiation with low-dose-rate has not yet been explored. In the present study, we, therefore, examined which RGS was modulated by the whole body radiation with low-dose-rate ($3.49mGy{\cdot}h^{-1}$). Among 16 RGS expression tested, RGS6, RGS13 and RGS16 mRNA were down-regulated by low-dose-rate irradiation. This is the first report that whole body radiation with low-dose-rate can modulate the different RGS expression levels. These results are expected to reveal the potential target and/or the biomarker proteins associated with male testis toxicity induced by low-dose-rate irradiation, which might contribute to understanding the mechanism beyond the testis toxicity.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.170-170
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• 2017

The highly valued ornamental plant, Platycodon grandiflorum for. duplex was generated by petaloidy of a calyx of Platycodon grandiflorum. The present investigation was executed to explore the several factors having effects on the germination of pollens with a view to acquire the underlying data for the artificial crossing to cultivate the species of Platycodon grandiflorum for. duplex. Both low and high temperature impaired the germination of Platycodon grandiflorum for. duplex pollens. The good germination rate was observed at the temperature of $25^{\circ}C$. The types and concentrations of carbon sources induced the differences in germination rate. The germination rate increased with the increasing concentration of sucrose and glucose except for fructose. Sucrose and glucose showed the highest results at the concentration of 20%. While fructose demonstrated the similar tendency to sucrose and glucose, it reduced the germination rate at the concentration of 20%. The highest germination rate was observed at the concentration of 15%. The appropriate carbon course for germination of pollens of Platycodon grandiflorum for. duplex was glucose of which germination rate was twice as high as that of sucrose and fructose. The germination rate was reduced substantially when the pH was close to alkali, and the potential germination rate was obtained at pH 6. Boric acid enhanced the germination rate at a lower concentration than the higher concentration.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.79-83
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• 2009

In this study, the characteristics of amorphous silicon etching for the formation of gate electrodes have been evaluated at the variation of several process parameters. When total flow rates composed of $Cl_2/HBr/O_2$ gas mixtures increased, the etch rate of amorphous silicon layer increased, but critical dimension (CD) bias was not notably changed regardless of total flow rate. As the amount of HBr in the mixture gas became larger, amorphous silicon etch rate was reduced by the low reactivity of Br species. In the case of increasing oxygen flow rate, etch selectivity was increased due to the reduction of oxide etch rate, enhancing the stability of silicon gate etching process. However, gate electrodes became more sloped according to the increase of oxygen flow rate. Higher source power induced the increase of amorphous silicon etch rate and CD bias, and higher bias power had a tendency to increase the etch rate of amorphous silicon and oxide.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.2
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• pp.109-120
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• 1997

Microstructure and mechanical properties of Fe-Si-Mn-P high strength steel sheet have been investigated by controlling the cooling rate. Bainite and ferrite were obtatined by annealing in the ferrite pluse austenite region, and ferrite and austenite were obtatined after annealing in the fully austenite region. Ferrite and pearlite were obtained when the cooling rate was controlled from the annealing temperature above $760^{\circ}C$ and bainite showed with increasing cooling rate, however below $760^{\circ}C$ ferrite and bainite were obtained. Tensile strengths and hardness nearly unchanged with increasing cooling rate after control the cooling rate from the temperature above $760^{\circ}C$, while tensile strengths increased and elongation decreased with increasing cooling rate when the cooling rate was controlled from the tempeature below $760^{\circ}C$. Without regard to annealing temperature, tensile strength increased and elongation decreased with increasing cooling rate. Tensile strengths and elongation values heat treated in the ferrite plus austenite region were higher than those in the fully austenite region. Retained austenite and strength-elongation balance showed the maximum value at $780^{\circ}C$ and decreased with increasing annealing temperature. Strength-elongation balance value was controlled by the retained austenite.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.2
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• pp.65-71
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• 2016

The new concept of agricultural water supply potential, which is mean annual turnover rate times unit storage capacity, was introduced for agricultural reservoirs. We investigated characteristics of mean annual turnover rate and unit storage capacity for agricultural reservoirs with storage capacity of over $1million\;m^3$. The curve of agricultural water supply potential represents change in mean annul turnover rate according to change in unit storage capacity. The mean annual turnover rate and unit storage capacity in the reservoirs with high minimum storage ratio are significantly higher than those in the reservoirs with low minimum storage ratio. Most of unstable water supply reservoirs showed low mean annual turnover rate or low unit storage capacity, indicating that mean annual turnover rate may be an index of stability degree for agricultural water use. The reservoirs with mean annual turnover rate of over 2 and unit storage capacity of over 0.8 m may be estimated as the stable water supply zone for 10 frequency dry year. The reservoirs with high agricultural water supply potential can belong to the wide range of stable water supply zone. The results suggest that relation between mean annual turnover rate and unit storage capacity may be used in evaluating stability degree for agricultural water supply in the reservoirs.

• Health Policy and Management
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• v.28 no.1
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• pp.15-22
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• 2018

Background: Health is affected by various local factors. This study aims to investigate the age-standardized mortality variation of Seoul as well as the characteristics of the factors related to the mortality variation. Methods: The Korea Community Health Survey data, Seoul Survey data, Seoul statistics, and e-regional indicators of the National Statistical Office were used. To investigate the basic boroughs standardized mortality variation in Seoul, external quotient, coefficient of variation (CV), and systematic component of variation (SCV) values were suggested; correlation analysis and multiple regression analysis were conducted to investigate the characteristics related to standardized mortality rate. Results: The highest and the lowest standardized mortality rate of Seoul by boroughs had as much as 1.4 times difference; a low level of variation was shown in CV by 8.2; and was shown in SCV by 79. As a result of the multiple regression analysis of the factors that affect standardized mortality variation, the higher the rate of householders with college or higher, the lower the standardized mortality rate, and the higher the high-risk drinking rate, the higher the standardized mortality rate. Of the two, the rate of householder with a degree equivalent or higher than college was shown to have the biggest impact, followed by high-risk drinking rate. Conclusion: We found a variation in age-standardized mortality rate of boroughs in Seoul. The results suggest that policy makers should take into account socioeconomic environmental characteristics of community in developing community-based health promotion rather than focusing on lifestyle changes of residents.