• Journal of the Korean Geophysical Society
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• v.8 no.3
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• pp.159-167
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• 2005

Turbulent fluxes of sensible heat and latent heat were analyzed at King Sejong station in the austral summer of 2002 (December) and 2003 (January and February). Monthly mean air temperatures of January and February (2.2oC) were similar to those averaged over 1988 to 2001. Precipitation was less in January and greater in February than those averaged over last 14 years. In December of 2002 and January, there was precipitation primarily when easterly wind blew usually. The frequency of snowfall was equal to or larger than that of rainfall. In the mean while, precipitation primarily in forms of rainfall occurred with westerly wind in February. In addition, while for easterly wind, temperature and humidity was low, temperature and humidity were high in case of westerly wind. Based on flux footprint, measured flux mainly came from within 300 m with maximum of 40 m upwind, indicating the insignificant role of the sea around the study site. Half-hourly downward short wave radiation amounted up to ∼ 1000 Wm-2 and net radiation ranged from -50 to 600 Wm-2. Half-hourly sensible heat flux was positive at daytime with maximum of ∼ 400 Wm-2, except the 27th and 28th in February of 2003 when it was negative all day despite of positive net radiation at short daytime. Latent heat flux was positive with maximum of ∼ 130 Wm-2. Depending on wind direction, the partitioning of net radiation into the sum of sensible heat flux and latent heat flux was larger than 0.8, indicating the strong source of the land surface for the atmospheric heating. The daytime averaged Bowen ratio (=sensible heat flux /latent heat flux) was significantly greater than 1, indicating that sensible heat flux was the main source to heat the atmosphere over the site.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.3
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• pp.400-405
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• 1997

Lead scandium niobate powders were prepared by a molten salt synthesis method using KCl as a flux. Variations in phase formation and particle morphology were investigated for the temperature range $700^{\circ}C$ to $850^{\circ}C$. Pure $Pb(Sc_{1/2}Nb_{1/2})O_3$ perovskite phase was formed at $850^{\circ}C$ after 2hrs and the average particle size of powder was below 0.5 $\mu\textrm{m}$. The results are discussed with respect to DTA, X-ray diffraction, and microstructural characterization data.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.174-184
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• 1997

Activated carbons were prepared from palm chars by steam activation. The effect of the activation temperature and time, steam concentration and flux on the n -butane adsorption properties were investigated on the basis of surface area, pore analysis and n-butane adsorption. The amount of n -butane adsorption increased with steam concentration and steam flux at higher activation temperature to the $900^{\circ}C$, however this tendancy on the activated carbons were not observed at the temperature above $900^{\circ}C$, It was shown that surface area was 978 $\textrm{m}^2$/g, average pore size was 9.3 $\AA$ and n-butane adsorption was 5.9 g /100ml in the activated carbons, prepared at $900^{\circ}C$, 185 minutes.

• Progress in Superconductivity
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• v.10 no.2
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• pp.74-78
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• 2009

Inter-grain nanobridges of the $MgB_2$ superconductor have been fabricated by focused-ion-beam(FIB) and their electrical transport properties were studied. The $MgB_2$ film was prepatterned into microbridges by a standard argon ion milling technique and then FIB-patterned into 100 nm$\times$100 nm bridges. Current-voltage characteristics showed a strong flux-flow type behavior at all temperatures with a trait of Josephson coupling near $T_c$. At low temperatures, the curves showed a two-step resistance-doubled transition with occasional hysteresis. The resistance-doubling transition is believed to be due to a two-channel flux-flow effect. The temperature-dependent critical current data showed $I_c(T){\propto}(1-T/T_c)^2$ near $T_c$, same as a normal barrier junction, and $I_c(T){\propto}(1-T/T_c)^{1.2}$ at low temperatures, similar to that of a film.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.3
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• pp.99-103
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• 2005

Lead scandium tantalate powders were prepared by a molten salt synthesis method using NaCl-KCl as a flux. Variations in phase formation and particle morphology were investigated for the temperature range from $700^{\circ}C\;to\;800^{\circ}C$. $Pb(Sc_{1/2}Ta_{1/2})O_3$, with pure perovskite phase was formed at $750^{\circ}C$ fur 2 hrs and the prepared powder had the cubic-like morphology and the average particle size below $0.5{\mu}m$. The results were discussed with respect to DTA, X-ray diffraction, and microstructural characterization data.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.6
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• pp.541-549
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• 2000

The present study experimentally investigated the effect of refrigeration oil on the condensation heat transfer for R-407C and R-22 in a microfin tube with a U-bend. POE oil ($74.1\;\textrm{mm}^2/s,\;40^{\circ}C$,) and mineral oil $62.5\;\textrm{mm}^2/s,\;40^{\circ}C$,) were used for R-407C and R-22 respectively Experimental parameters were an oil concentration from 0 to 5%, a mass flux from 100 to $400kg/m^{2}s sand an inlet quality from 0.5 to 0.9. The enhancement factors for both R-22 and R-407C refrigerants at the first straight section decreased continuously as the oil concentration increased. They decreased rapidly as the mass flux decreased and the inlet quality increased. The heat transfer coefficients in the U-bend showed the maximum at the $90^{\circ}$/TEX> position. The heat transfer coefficients at the second straight section within the dimensionless length of 48 were larger by a maximum of 33% than the average heat transfer coefficient at the first straight section.

• 한국초전도학회:학술대회논문집
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• v.11
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• pp.12-12
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• 2001

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.209.2-209.2
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• 2008

• Journal of Pharmaceutical Investigation
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• v.40 no.2
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• pp.91-100
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• 2010

The objective of this work is to study transdermal delivery of donepezil hydrochloride (DH) using iontophoresis and to evaluate various factors which affect the transdermal transport. After the flux study using 4 kinds of hydrogel, hydrogel containing 8% poly(ethylene oxide) (PEO) was chosen as the hydrogel for further studies. Under experimental condition, DH was stable. We have studied the effect of polarity, current density, drug concentration and current profile on transdermal flux and compared the results. In vitro flux study was performed at $33^{\circ}C$, using side-by-side diffusion cell and full thickness hairless mouse skin. DH is positively charged at pH 7.4, and anodal delivery was much larger than cathodal and passive delivery at all current densities studied (0.2, 0.4 and 0.6 mA/$cm^2$). Cathodal delivery showed higher flux than passive flux. Flux increased as the concentration of DH in hydrogel increased. Pulsatile application of current showed smaller flux value than the application of continuous current. Based on these results, we have evaluated the possibility of delivering enough amount of DH to reach the therapeutic level. The maximum cumulative amount of DH transported for 12 hours was 455 ${\mu}g/cm^2{\cdot}hr$ when the amount of DH in the hydrogel was 3 mg/mL and the current density was 0.4 mA/$cm^2$. If the patch size is 10 $cm^2$, then we can deliver 4.6 mg for 12 hours. Because the daily dosage of DH is 5 mg, it seems possible to deliver clinically effective amount of DH using iontophoresis. This study also provides some information about the role of electrorepulsion and electroosmosis during the transport through skin.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.113-123
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• 2017

This study investigated effects of physical and chemical cleaning methods on the initial flux recovery of fouled membrane in membrane distillation process. A laboratory scale direct contact membrane distillation (DCMD) experiment was performed to treat digested livestock wastewater with 3.89 mg/L suspended solids, 874.7 mg/L COD, 543.7 mg/L nitrogen, 15.6 mg/L total phosphorus, and pH of 8.6. A hydrophobic PVDF membrane with an average pore size of $0.22{\mu}m$ and a porosity of 75 % was installed inside a direct contact type membrane distillation module. The temperature difference between feed and permeate side was maintained at $40^{\circ}C$ with the feed and permeate stream velocity of 0.18 m/s. The results showed that the permeate flux decreased from $22.1L{\cdot}m^{-2}{\cdot}hr^{-1}$ to $19.0L{\cdot}m^{-2}{\cdot}hr^{-1}$ after 75 hours of distillation. The fouled membrane was cleaned first by physical flushing and consecutively by chemicals with NaOCl and citric acid. After the physical cleaning the flux was recovered to 92 % as compared with the initial clean water flux of the virgin membrane. Then 94 % of the flux was recovered after cleaning by 2,000 ppm NaOCl for 90 minutes and finally 97 % of flux recovered after 3 % citric acid for 90 minutes. SEM-EDS and FT-IR analysis results presented that the foulants on the membrane surface were removed effectively after each cleaning step. The contact angle measurement showed that the hydrophobicity of the membrane surface was also restored gradually after each cleaning step to reach nearly the same hydrophobicity level as the virgin membrane.