• Korean Journal of Food Science and Technology
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• v.50 no.2
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• pp.165-171
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• 2018

Atmospheric-pressure plasma (APP) was applied to determine quality characteristics of brown rice (BR) and white rice (WR) of Samkwang and Palbangmi. APP (250 W, 15 kHz, ambient air) was generated and dielectric barrier discharge was applied for 0, 10, and 20 min for 2 weeks at 4 and $25^{\circ}C$. The growth of total aerobic bacteria and mold increased depending on the storage. Water content of BR and WR decreased by storage temperature and periods. No viable counts were detected for molds by APP-treated 20 min at $4^{\circ}C$. Changes in protein and damaged starch contents in plasma were not observed. Amylose contents were not changed, but WR (Palbangmi) showed a tendency to increase. The results show that APP improved the microbial quality of BR and WR of Samkwang and Palbangmi, although further studies should be conducted to determine change in quality by APP.

• Analytical Science and Technology
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• v.14 no.3
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• pp.274-285
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• 2001

In this study, the thermal desorption-cryofocusing-gas chromatographic(TD-C-GC) method was developed for determination of volatile organic compounds(VOCs) in ambient air and was applied at the municipal solid waste landfill sites. On-column cryofocusing was possible only with a 100 ml dewars bottle in TD-C-GC method with a stainless steel column. However, high operating pressure was needed for purging VOCs from the absorbent trap, which was able to solve by pressure programming with a electric pressure controller. By using both pressure and temperature programming brought increasing of resolution power in on-column cryofocusing method, but the high pressure caused a leakage of sample tube with repeated use. A loop cryofocusing devise was also developed and compared with the direct on-column method. In loop cryofocusing method, VOCs were concentrated on a 0.8mm i.d. loop which is located between the injector and separation column by using liquid nitrogen. In order to purge VOCs from the absorbent trap, only 0.4 psi of pressure was need in the loop cryofocusing method. Dual detection system was applied for the analysis of VOCs; a FID was used for hydrocarbons and a FPD was used for sulfur-containing compounds. Qualitative analysis was done by on-column cryofocusing GC-MS system. Among the large number of VOCs, toluene was the most abundant. Hydrogen sulfide, dimethyl sulfide, carbon disulfide, dimethyl disulfide and methyl propyl disulfide were detected at landfill site by FPD.

• Analytical Science and Technology
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• v.18 no.3
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• pp.232-240
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• 2005

The total PCBs level in the transformer insulation oil samples using GC/ECD and HRGC/HRMS were ranged from 0.087 to $223.6{\mu}g/g$ and ranged from N.D. to $154.04{\mu}g/g$, respectively. The calculated TEQ values were ranged from 0.00067 to 6.8 ng WHO-TEQ/g. Among the samples, 6 samples showed higher than 2 ppm concentration (specific waste criterion of Korea). A variety in the concentration of total PCBs were observed between ECD and HRMS analysis. This is maybe due to quantification mehtod. The Aroclor 1248 wasn't present in the samples. The distribution pattern of Co-PCB congeners showed that the ratio of monoortho substituted congeners were higher than non-ortho substituted congeners. Among that, PCB-167 congener was predominant. In addition, the distribution of Co-PCBs congeners was different with that of flue gas and ambient air samples as well as commercial PCB formulations (Aroclor, Kanechlor).

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.1
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• pp.119-129
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• 2005

The ambient TSP data measured at Seoul, Incheon. Taean, Daegu, Busan in Korea were used to explain the chemical composition and general features of Asian Dust (AD) observed in Korea. 9 episodes out of 19 were sampled from 2000 through May 2002, and measurements were conducted covering ionic and metal components with mass concentration. The results showed that daily averaged mass concentration (TSP) during the AD episodes was 458 $\mu\textrm{g}$/㎥, and ionic and metal concentrations were 27.93 $\mu\textrm{g}$/㎥ and 71.7 $\mu\textrm{g}$/㎥, respectively, accounting for 6.1 % and 15.5% of the total aerosol mass. TSP concentrations during episodes were varied from 120 to 1742 $\mu\textrm{g}$/㎥ according to the impact of Asian Dusts and had a tendency of showing higher values at sites in the west side of Korea, which can be explained by the effect of diffusion and deposition. In this study, ionic components like Ca (NO$_3$)$_2$, CaSO$_4$, NaNO$_3$, Na$_2$SO$_4$ were prominent types in secondary aerosol during AD periods and also indicated that V, Co as well as soil elements such as Ca, Fe, Mg, Mn, K correlated well with Al, while Cu, Cd, Pb, Zn didn't agree well with it. In addition, enrichment factors (EFs) for each metal component were obtained to provide simple information about source contribution of Asian Dust, and the results were compared with those from other AD studies. In this study, the results showed that aerosol properties in Korea during the Asian Dust were considerably different from those of general atmospheric condition and specially varied from case to case rather than site to site, which implies that there are certain variations in the soil of source region, pathways of air mass, and meteorological condition. For the enhanced study, those factors should be combined with the features of Asian Dust resolved from this study.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.118-128
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• 2016

As the interest on the air-pollution is gradually rising up at home and abroad, automotive and fuel researchers have been working on the exhaust emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative after-treatment systems, using clean (eco-friendly alternative) fuels and fuel quality improvement. This research has brought forward two main issues : exhaust emission and PM (particulate matter) particle emissions of gasoline vehicle. Exhaust emission and PM particle of automotive had many problem that cause of ambient pollution, health effects. In addition, researcher studied the environment problems of the MTBE contained in the fuel as oxygenate additives. The researchers have many data about the health effects of ingestion of MTBE. However, the data support the conclusion that MTBE is a potential human carcinogen at high doses. Based on the oxygenated fuel additive types (MTBE, Bio-ETBE, Bio-ethanol, Bio-butanol), this paper discussed the influence of oxygen contents on gasoline fuel properties and evaporative emission characteristics. Also, this paper assessed the acceleration and power performance of gasoline vehicle for the fuel property.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.143-150
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• 2010

This study examined the effect of cold water finger immersion at various water temperature on cold-induced vasodilation (CIVD) and its reproducibility to the cold stress. Ten healthy collegiate men ($21.4{\pm}2.5$ yrs, $175.8{\pm}4.1$ cm, $69.6{\pm}7.6$ kg, $11.2{\pm}3.7$ %fat) underwent two tests. At the first test (1ST), subjects immersed their middle fingers at $43^{\circ}C$ water for 5 min followed by a resting at an ambient air for 25 min. Then they immersed the finger at one of the five water temperatures (Tw: 5, 8, 11, 14, or $17^{\circ}C$) at random order for 20 min. Once a testing at one Tw was completed, they immediately repeated the testing procedure for another Tw. The second test(2ND) was performed within a week after 1ST with having an identical procedure of 1ST except the order of Tw. During the test, rectal temperature, finger temperature from middle finger nail bed, and heart rate were measured every six second. In conclusion, maximal finger temperature(Tfmax), and Tfmax minus Tw was highly reproducible in this experiment. Minimal finger temperature (Tfmin) and Tfmax were higher as Tw decreased. And Tfdiff was higher as the colds tress decreased. No differences were found in time variables of temperature responses.

• Korean Journal of Bronchoesophagology
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• v.6 no.1
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• pp.29-37
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• 2000

Background and Objectives : The concentration of sulfur dioxide($SO_2$) gas in the ambient air appears increasing in the industry and urban area day by day. It was known that $SO_2$ is noxious gas. $SO_2$ can be irritating to the eyes, nose, throat, upper respiratory tract and skin. It produces sulfurous acid on contact with water and is extremely irritating to the nasopharynx and respiratory tract. Laminin is a family of extracellular matrix glycoproteins localized in the basement membrane that separates epithelial cells from the underlying stroma. The biological activities of laminin are to promote cell migration, wound healing, growth and differentiation. Meterials and Methods : The histologic changes and the expression of laminin in tracheal mucosa sacrificed at every weeks (to 7 weeks) after continued $SO_2$ exposure of 250ppm for 30 minutes a day were studied in rats. Results : Pathologic tissue was formed at the tracheal mucosa and the underlying tissue by the infiltration of monocytes and epithelium was transformed to the single cell layered epithelium above 5 weeks after exposure. At the 6 weeks after exposure, epithelial cells were partially lost and epithelial cell layer was transformed to be leaf-shaped. Submucosal tissue was transformed to be lymphatic tissue. An intense positive staining for laminin was found in apical cytoplasm and lateral surface of the normal epithelial cells and basement membrane but at the 5 and 6 weeks after exposure, laminin activity was decreased to the moderate activity. At the 7 weeks after exposure, laminin activity was decreased to the weak activity. Conclusion : Our finding suggests that $SO_2$ makes histologic damage on the tracheal mucosa and decreases immunoreactivity for laminin. Longer duration of the exposure of $SO_2$ makes more histologic damage on the tracheal mucosa and decreases immunoreactivity for laminin.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.288-294
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• 2013

Recently, sustainable production of biofuel using algal biomass is being pursued because of its enormous potential. First and foremost, securing superior strains to develop an efficient production system for algal biodiesel through screening or genetic improvement of microalgae is necessary. The genus of Botryococcus is regarded as one of the superior microalgae for biodiesel production due to its ability to accumulate high amounts of lipids and hydrocarbons. However, its low growth rate is a bottleneck for large-scale production and commercialization. The purpose of this study is to obtain indigenous Botryococcus strains which possess high lipid content and biomass productivity. The Botryococcus sp. was isolated from the Seobu Reservoir in Jeju Island and identified as Botryococcus sudeticus J2 by comparative analysis of 18s rRNA gene and ITS regions. The biomass productivity and lipid content of B. sudeticus J2 were 0.116 g $L^{-1}day^{-1}$ and 40.1% of dry wt., respectively. This was higher than the value of B. braunii UTEX 572, which is widely regarded as a superior strain among Botryococcus species. The relatively high growth rate of B. sudeticus J2 was achieved under a light intensity of 240 ${\mu}mol$ photons $m^{-2}s^{-1}$ with ambient air spargingwhen compared to 120 ${\mu}mol$ photons $m^{-2}s^{-1}$ with 2% $CO_2$ supply. In summary, it is likely that the isolated B. sudeticus J2 can be used for the mass cultivation and biodiesel production.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.538-545
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• 2020

The outdoor coal storage sheds of thermal power plants are being converted to indoor coal storage sheds worldwide because of the environmental pollution problems in the surrounding areas. On the other hand, indoor coal storage sheds are causing problems, such as indoor coal scattering and harmful gas generation. In this study, the ventilation method of indoor coal storage sheds was analyzed in terms of the internal flow characteristics and ventilation according to the outside wind velocity and direction. CFD analysis was performed based on the actual flow measurement information inside the indoor coal storage sheds. A comparison of the wind speed of 6 m/s and 2 m/s when the outside wind direction was easterly showed that the stream velocity to the monitor louver was faster and the recirculation area was clearer at 6 m/s than at 2 m/s. In addition, the trend of a westerly wind was similar to that of the easterly wind. The ventilation rate according to the wind speed was 13.1 times and 4.4 times for a wind speed of 6 m/s and 2 m/s, respectively. If the wind speed is 2 m/s, the situation does not meet the required number of ventilations per hour in a general plant, and needs to be improved.

• Membrane Journal
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• v.22 no.1
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• pp.8-15
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• 2012

Tubular $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ membranes with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer were prepared by extrusion and dip coating technique. XRD and SEM result showed the tubular membrane possessed the perovskite structure and porouscoating layer (thickness= about $2{\mu}m$) in surface. The oxygen permeation test was measured at condition of ambient air (feed side) and vacuum (permeate side) in the temperature range from 750 to $950^{\circ}C$. The oxygen permeation flux of $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane with $La_{0.6}Sr_{0.4}Ti_{0.3}Fe_{0.7}O_{3-{\delta}}$ porous coating layer reached maximum $3.2mL/min{\cdot}cm^2$ at $950^{\circ}C$ and was higher than non-coated $Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-{\delta}}$ tubular membrane. Long-term stability test result indicated that the oxygen permeation flux was quite stable during the 11 day.