• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.7
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• pp.557-570
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• 2014

The heat transfer, pressure loss, and thermal performance in a cooling channel were evaluated for various new fan-shaped pin-fin geometries using three-dimensional Reynolds-averaged Navier-Stokes equations. The turbulence was modeled using the low-Reynolds-number SST turbulence model in the Reynolds number range of 5,000-100,000. The numerical results for the area-averaged Nusselt numbers were validated by comparing them with the experimental data under the same conditions. A parametric study for three types of fan-shaped pin-fin geometries was performed with two parameters, namely, the leading and trailing reduction angles.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.12
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• pp.795-801
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• 2008

An experimental study has been performed on the single phase flow and convective heat transfer in trapezoidal microchannels. The microchannel was about $270{\mu}m$ wide, $800{\mu}m$ deep. and 7 mm long, which might ensure hydrodynamically fully-developed laminar flow at a low Reynolds number. The experiments were conducted with R1l3 and water, with the Reynolds number ranging from approximately 30 to 5000 for friction factor and 30 to 700 for the Nusselt number. Friction factors in laminar are found to be in good agreement with the predictions of existing correlation suggesting that a conventional analysis approach can be employed in predicting flow friction behavior in microchannels. However turbulent friction factors are hardly predictable by the existing correlations. The experimental results show that the Nusselt number is not a constant but increases almost linearly with the Reynolds number even the flow is fully developed (Re < 100). The dependence of the Nusslet number on the Reynolds number is contradictory to the conventional theory. At a Reynolds number greater than 100, the Nusselt number increases slowly with the Reynolds number, where thennally developing flow is responsible for the increase of the Nusselt number with the Reynolds number.

• Animal cells and systems
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• v.16 no.6
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• pp.469-478
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• 2012

Sex hormones have long been considered to play an important role in bone turnover rate, periodontal diseases, and wound healing. We have studied the effect of porcine testis steroid extract (PTSE), an extract of porcine testes, which holds a good ratio of 19-nortestosterone (nandrolone), testosterone, androstenedione, $17{\beta}$-estradiol, and estrone, on the healing rate of a standardized full-thickness linear wound on the back of the rat. Skin punch or carbon dioxide ($CO_2$) laser methods were used to create the deep skin injury in two groups of animals. The animals were treated with the PTSE cream, control cream and Vaseline (control) to find out the effect in re-epithelialization, contraction, and formation of granulation and scar tissues. Histological examination after 21 days showed 100, 87.4, and 80.5% recovery of epidermis, dermis, and hypodermis, respectively in the PTSE-treated animals. Similarly, on the 15th day of treatment, complete healing of intact skin was observed in the PTSE cream-treated animals among the laser radiation group. Even though the beginning of re-epithelialization phase and completion of serum crust formation was also observed in the base cream- and Vaseline-treated animals respectively, the complete healing cycle was observed only in the PTSE-treated group. The white blood cell count in the PTSE-treated group showed that PTSE cream is nontoxic to animals.

• Publications of The Korean Astronomical Society
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• v.22 no.4
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• pp.201-209
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• 2007

We have preliminarily designed two infrared optical systems of the multi-purpose infrared camera system (MIRIS) which is the main payload of STSAT-3. Each optical system consists of a Cassegrain telescope, a field lens and a 1:1 re-imaging lens system that is essential for providing a cold stop. The Cassegrain telescope is identical for both of two infrared cameras, but the field correction lens and re-imaging lens system are different from each other because of different bands of wavelength. The effective aperture size is 100mm in diameter and the focal ratio is f/5. The total length of the optical system is 300mm and the position of the cold stop is 25mm from the detector focal plane. The RMS spot size is smaller than $40{\mu}m$ over the whole detector plane.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.595-600
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• 2019

This study investigated the suitability of freeze-dried ice plant (Mesembryanthemum crystallinum) as the source of an edible healthy salt alternative by examining the content of NaCl, D-pinitol, total phenols, total flavonoids, and DPPH radical scavenging activity compared with those of natural and purified salts. Our results showed that the NaCl content of freeze-dried ice plant, natural and purified salts was 19, 94 and 99%, respectively. The D-pinitol content of freeze-dried ice plant was 777 mg/100 g, whereas D-pinitol was not detected in either natural or purified salts. The total phenol and flavonoid contents of freeze-dried ice plant were 115 mg GAE/100 g and 985 mg RE/100 g, respectively. The DPPH radical scavenging activity of freeze-dried ice plant was markedly higher than that of natural and purified salts. Altogether, these results show that freeze-dried ice plant contains both NaCl and bioactive compounds and can be used as a source of edible salt with positive health effects.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.3
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• pp.389-396
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• 2014

The physiological properties of 70% ethanol extracts from Portulaca oleracea with different extraction methods (reflux extraction, RE; autoclave extraction, AE; low temperature high pressure extraction, LTPE) were investigated. The freeze-dried powder yields of RE, AE, and LTPE were 33.78%, 30.80%, and 11.05%, respectively. The color values of L and b were higher in LTPE, and the chroma values were higher in AE and LTPE compared to RE. The total polyphenolics and proanthocyanidin contents in LTPE were significantly higher than in other extracts. The amount of substances related to flavonoids contents was highest in RE (4.30 mg/g), followed by AE (4.06 mg/g), and LTPE (4.00 mg/g). DPPH radical scavenging ability with a concentration of 500 mg% (w/v) were in the following order; LTPE (88.87%)> RE (83.84%)> AE (80.67%). Further, the reducing power, ABTS radical scavenging ability, and nitrite scavenging activity was observed in the same tendency as seen with the DPPH radical scavenging ability. However, the ferrous ion chelating activity of RE (85.45%) and AE (83.88%) was significantly higher than that of LTPE (75.60%). ${\alpha}$-Glucosidase inhibitory activities of RE and LTPE with a concentration of 100 mg% were significantly higher than AE. Xanthine oxidase, and acetylcholinesterase inhibitory activities of LTPE were higher than the other extracts. These results suggest that the extracts from Portulaca oleracea have the potential to act as functional materials, and components of Portulaca oleracea could be effective in the prevention of Alzheimer's disease, and may be used to develop various functional food products.

• Korean Journal of Medicinal Crop Science
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• v.17 no.5
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• pp.352-356
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• 2009

In this study, raw ginseng water extract solutions were analyzed to set up the functional saponin content and quality optimization condition. The highest saponin content among the total raw ginseng water extracts was $74.6\;mg/100\;m{\ell}$ which was extracted at $75^{\circ}C$ for 24 hours. In addition, the saponin content decreased according to the increased extraction temperature and time. The highest total content of $Rb_2$ and Re was $19.9\;mg/100\;m{\ell}$ at $75^{\circ}C$ for 12 hours which decreased according to the increased extracted temperature and time. The highest prosapogenin ($Rg_2\;+\;Rg_3\;+\;Rh_1$) content among the total raw ginseng water extracts was $28.6\;mg/100\;m{\ell}$ which was extracted at $85^{\circ}C$ for 36 hours. The reducing sugar content, sweetness and turbidity were increased according to the increased extraction temperature and time. But pH were decreased according to the increased extracted time.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.100-106
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• 2017

Nanosized and aggregated $Y_2O_3:Eu$ Red phosphors were prepared by template method from metal salt impregnated into crystalline cellulose. The particle size and photoluminescent property of $Y_2O_3:Eu$ red phosphors were controlled by variation of the calcination temperature and time. Dispersed nanosol was also obtained from the aggregated $Y_2O_3:Eu$ Red phosphor under bead mill wet process. The dispersion property of the $Y_2O_3:Eu$ nanosol was optimized by controlling the bead size, bead content ratio and milling time. The median particle size ($D_{50}$) of $Y_2O_3:Eu$ nanosol was found to be around 100 nm, and to be below 90 nm after centrifuging. In spite of the low photoluminescent properties of $Y_2O_3:Eu$ nanosol, it was observed that the photoluminescent property recovered after re-calcination. The dispersion and photoluminescent properties of $Y_2O_3:Eu$ nanosol were investigated using a particle size analyzer, FE-SEM, and a fluorescence spectrometer.

• Korean Journal of Pharmacognosy
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• v.38 no.1
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• pp.84-89
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• 2007

The present study describes the preliminary evaluation of the antioxidant activities and the neuroprotective effect of methanolic extracts from Psoralea corylifolia Linne (PCE). The antioxidant activities and neuroprotective effect of the PCE were evaluated by total phenolic contents (TPC), DPPH radical scavenging activity (RSA), reducing power (RP), MTT reduction assay, and LDH release assay. TPC, DPPH RSA, and RP of the extract at concentration of 100 ${\mu}g$ was 125.93 ${\mu}g$, 63.81%, 0.138, respectively, and those were concentration dependent. The treatment of PC12 and N18-RE-105 cells with various PCE concentrations under $H_2O_2$ resulted in the induction of protective effect in a dose-dependent manner, as determined by the results of an MTT reduction assay and LDH release assay. Therefore, these results suggest that PCE could be a new potential candidate as an antioxidant against neuronal diseases.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.2
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• pp.30-35
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• 2003

Flow characteristics of blood flow in a micro channel were investigated experimentally using a micro-PIV (Particle Image Velocimetry) velocity field measurement technique. The main objective of this study was to understand the real blood flow in micron-sized blood vessels. The Reynolds number based on the hydraulic diameter of micro-channel for deionized (DI) water was about Re=0.34. For each experimental condition, 100 instantaneous velocity fields were captured and ensemble-averaged to get the spatial distributions of mean velocity. In addition, the motion of RBC (Red Blood Cell) was visualized with a high-speed CCD camera. The captured flow images of nano-scale fluorescent tracer particles in DI water were clear and gave good velocity tracking-ability. However, there were substantial velocity variations in the central region of real blood flow in a micro-channel due to the presence of red blood cells.