• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.5
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• pp.605-611
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• 2008

Antioxidant activity of wa-song (Orostachys japonicus A. Berger) was analyzed to clarify the influence of extractive solvent and drying method such as sun, hot-air and freeze drying. The contents of total phenols and flavonoids were significantly higher in 95% ethanol extracts than water extracts. Ability of reducing power and DPPH radical, hydroxyl radical and nitrite scavenging ability were higher in the order of hot-air dried sample> freeze dried sample> sun dried sample and these abilities were also higher in 95% ethanol extracts than water extracts. In conclusion, antioxidant activities of wa-song extracts were in proportion to the contents of total phenols and flavonoids. Also, hot-air drying is the superior method for the enhancement of antioxidant activity of wa-song.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.639-645
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• 2008

The objectives of this research are to (1) observe changes in particle size distribution due to formation of microflocs during coagulation process (2) identify the membrane fouling potential on cross flow system (3) investigate the mechanism of membrane fouling. The rate of flux decline for the hydrophobic membrane was significantly greater than for the hydrophilic membrane, regardless of pretreatment conditions. The pretreatment of the raw water significantly reduced the fouling of the UF membrane. Also, the rate of flux decline for the hydrophobic membrane was considerably greater than for the hydrophilic membrane. Applying coagulation process before membrane filtration showed not only reducing membrane fouling, but also improving the removal of dissolved organic materials that might otherwise not be removed by the membrane. That is, during the mixing period, substantial changes in particle size distribution occurred under rapid and slow mixing condition due to the simultaneous formation of microflocs and NOM precipitates. Therefore, combined pretreatment using coagulation not only improved dissolved organics removal efficiency but also flux recovery efficiency.

• KSBB Journal
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• v.28 no.5
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• pp.319-326
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• 2013

This study was carried out to investigate the in vitro and in vivo moisturizing properties and percutaneous absorption of PEG-impregnated Aloe vera gel. The PEG-i-Aloe gel was obtained from dewatering and impregnation by soaking (DIS) of Aloe vera leaf slice. The moisturizing property of the obtained sample was evaluated by moisture determination using gravimetric method in desiccator under different RH% and by water sorption-desorption test on human skin. The transdermal penetration characteristics of PEG-i-Aloe gel was investigated by Franz diffusion cell in vitro transdermal absorption method. PEG-i-Aloe gel had high moisture retention ability and could significantly lead the enhancing skin hydration status as well as reducing the skin water loss due to the film formation as a skin barrier. The skin penetration rate of PEGi- Aloe gel at steady state was 9.76 ${\mu}g/(h{\cdot}cm^2)$ and the quantity of the transdermal absorption was 144 ${\mu}g/cm^2$ in 9 hr. The penetration mechanism was well fitted with Higuchi model ($R^2$ = 0.974-0.994). The results show that PEG-i-Aloe gel has the significant moisturizing effect and strong penetration of the animal skin. It could be used as the moisturizing additive in cosmetic skin products.

• Journal of the Korean Electrochemical Society
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• v.10 no.2
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• pp.126-131
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• 2007

The durability problem of Prussian blue in non-aqueous $Li_+$-based electrolytes has been due to the degradation of the Prussian blue electrode matrix during the insertion/extraction processes by $Li_+$. In this work, we designed and synthesised the Prussian blue without reducing the electrochromic performance in non-aqueous $Li_+$-based electrolytes. Prussian blue was electrodeposited on a glass which has ITO coating, and the coating solution is a mixture solution of $FeCl_3\;and\;K_3Fe(CN)_6$ with deionized water added HCl, KCl, and LiCl, respectively. The durability of Prussian blue was evaluated by an in-situ transmittance measurement during a continuous and pulse potential cycling test, and measured by electroactive layer thickness due to evaluating the degradation.

• The Korean Journal of Emergency Medical Services
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• v.9 no.1
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• pp.33-41
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• 2005

In Korea, the number of those who were drowned of the dead by 'accident and injury' ranked the third of causes of death is over 2,300 people a year. So the Ministry of Home Affairs arranged '119 drowning rescue team' at frequent occurrence regions of drowning temporarily as a part of drowning rescue measures during every summer season and made perfection more perfect for safety control and rescue services at prevention areas of accidents. However, considering that the number of professional drowning rescuers is small and it is managed temporarily only for summer, the placement of special rescue team equipped with professional education and qualification should be ensured and quick lifesaving and first-aid treatment should be conducted, since much time is required to arrive at accident place after receiving accident report at 119 office, rapid rescue and relief have not been achieved. Therefore, the placement of special rescue team should be increased for reducing the personal damages by considering regional characteristics and in particular placement of more drowning rescue teams in Jeonnam region which has more seas and rivers is needed This study aims at analyzing relief activities and statistics to cope with water accidents and achieve qualitative growth of first-aid services, examining actual conditions of water accident relief team and personnel assignment, providing first-aid services of good quality and establishing improvement methods to increase operation of relief team.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1101-1105
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• 2014

Ocean Thermal Energy Conversion(OTEC) which uses the temperature difference between warm surface sea-water and cold deep sea-water to produce electric power is the promising technology. OTEC is able to be utilized as the $CO_2$ reducing technology by using the consistent temperature differential, while the system efficiency is very low. Thus, the design and development of a efficient turbine is essential to improve the system efficiency for OTEC. In this study, a 100kW-class radial inflow turbine using R32 was designed for OTEC and this turbine's performance was estimated by analysis of CFD. According as the simulation results, turbine's geometry was corrected. The radial inflow turbine satisfying the requirements is designed by the repeated attempts.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.3
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• pp.771-776
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• 2003

The present study was conducted to evaluate the regulation mechanism of nitric oxide(NO) by water-extracted Cyperus rotundus (WCR) in RAW 264.7 macrophages. We investigated the effects of cell proliferation in mouse spleen cell and RAW 264.7 macrophages cells. WCR enhanced mitogenic activity in the dose-response manner in mouse spleen cells and RAW 264.7 macrophages cells. In nitric oxide (NO) synthesis by WCR, WCR alone had an effect on NO synthesis. It was found that the production of NO of RAW 264.7 cells stimulated with lipopolysaccharide (LPS) could be markedly inhibited by WCR. Inhibition of NO production was achieved by reducing inducible nitric oxide syntheses(iNOS) mRNA expression. The expression of IL-I gene by WCR was investigated using reverse transcription polymerase chain reaction (RT-PCR). In RT-PCR, IL-1 family(IL-1 α, IL-1β) expressions were induced by WCR. These finding suggested that regulation of NO production by WCR may be, at least in part, associated with the regulation of iNOS mRNA expression and IL-1 family gene expression.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.1
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• pp.1-7
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• 2016

A Urea-SCR(Selective Catalytic Reactor) system, which converts nitrogen oxides into nitrogen and water in the presence of a reducing agent, creates a major exhaust gas aftertreatment system for NOx reduction among other compounds. With regard to vehicle applications, a urea solution was chosen based on its eutectic composition of a 32.5wt% urea-water solution. An important advantage of this eutectic composition is that its melting point of $-11.7^{\circ}C$ is sufficiently low to avoid solidification in cold environments. However, the storage tanks must be heated separately in case of low ambient temperature levels to ensure a sufficient amount of liquid is available during scheduled start ups. In this study, therefore, a numerical investigation of three-dimensional unsteady heating problems analyzed to understand the melting processes and heat transfer characteristics including liquid volume fraction, temperature distributions, and temperature profiles. The investigations were performed using Fluent 6.3 commercial software that modeled coolant and electric heater models based on a urea solution. It is shown that the melting performance with the electric heater is higher than a coolant heater and is more efficient.

• Transactions of the KSME C: Technology and Education
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• v.2 no.1
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• pp.65-72
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• 2014

The purpose of this study is to design a heat insulator for reducing available energy loss in stratified thermal storage tank. Heat insulator is operated by buoyancy effect from density difference between hot and cold water without extra equipment. Analysis model using the Matlab Simulink was developed to estimate the internal temperature distribution in thermal storage tank and also used to select proper material and thickness of the heat insulator. Operational feasibility was confirmed through reduced scale experiment. As a result, heat insulator can effectively delay the formation of thermal boundary layer between hot and cold water. In reduced scale experiment, heat insulator can preserve additional 1540J of available energy. When applied to the real thermal storage tank, increase of 6% thermal storage efficiency can be expected.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.3
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• pp.292-303
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• 2002

This paper presents experimental results for early-age properties of concrete such as the setting time and strength, evaluated via the ultrasonic pulse velocity (UPV). Developing and using an automatically-recording monitoring system, the UPV's of mortar and concrete with various water to binder ratios (W/B) were measured during the first 24 hours. In addition, probe penetration and compression tests were conducted to measure the setting time and compressive strength, respectively. It was observed that the UPV's of mortar with high W/B remained constant during the first 6.5 hours and then abruptly began to increase at constant rates. On the other hand, the UPV of mortar with low W/B increased relatively slowly and gradually due to the setting retardation caused by the use of high range water reducing agent (HRWR). It was found that setting of concrete occurs when the UPV reaches a certain value. Moreover, it was concluded that the estimation formulas should incorporate the effects of W/B to more accurately estimate the early-age strength of concrete from the UPV.