• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1134-1140
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• 2010

Ozonation is a promising process that can effectively reduce the occurrence of micropollutants and pathogen in water. This study investigated the performance of ozonation for the removal of pharmaceuticals and personal care products (PPCPs) in secondary effluent from wastewater treatment plant. Moreover, the disinfection potential of ozonation applied for PPCPs removal was discussed. Secondary effluent filtered by sand filter was used for tested water, and ozonation was performed under 2, 4 and 6 mg/L of ozone doses. As a result, 6 mg/L of ozone dose (ozone consumption : 4.4 mg/L) was essential for the effective removal of 37 PPCPs in tested water. Several previous studies showed that the operation condition could achieve approximately 3 log inactivation of total coliform and enteroviruses. On the other hand, dissolved ozone concentration in tested water increased by 1.8 mg/L under 6 mg/L of ozone dose, probably resulting in the increase of bromate formation potential. This result implies that as alternatives to suppress the bromate formation potential during the oxidation of PPCPs by ozone, investigations on advanced oxidation processes are required.

• Journal of Astronomy and Space Sciences
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• v.18 no.3
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• pp.239-248
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• 2001

Far-ultraviolet IMaging Spectrograph (FIMS) is the main payload of the first Korean scientific satellite, KAISTSAT-4, which will be launched in 2002. Among the optical parts, parabolic cylinder mirror does not have any heritage from previous astronomical missions, so the manufacturing and testing process itself is a challenging issue. We describe the method of manufacturing and measuring of the off-axis parabolic cylinder mirror and our initial experiments to establish the entire manufacturing process. Using the method, the profile error can meet the specification of $lambda$ per cm which is closely related with the astronomical performances. In case of the surface roughness, temperature controlled pitch polishing reduces $R_{q}$ under 1 nm implying that scattering in the entire spectral range of FIMS is less than 2% of the incident UV light.

• Journal of fish pathology
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• v.18 no.1
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• pp.91-97
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• 2005

Bio-secure culture of olive flounder Paralichthys olivaceus in the IBK (Intensive Bioproduction Korean) recirculating system with dry pellet was tested for 6 months. The IBK system consists of 12 rearing tanks, 6 sedimentation tanks. 4-sectioned submerged biofilter chamber and channels. The size of each rearing tank was 3m in diameter and 1m in depth. The size of each biofilter chamber was $3.1\times3.3\times2.0$ m (D) and was filled with corrugated plastic plates as a biofilter medium. Total surface area of the biofilter was 3,789.7 $m^2$ Water was circulated by one of two vertical axial pump and circulating rate was about 34 times per day. A UV light sterilizer was used to treat inlet sea water with the flow rate of 4 ton/hr. All fish were treated with 150 ppm formalin 3 times with 5 day interval before stocking. It took 60 days for 'conditioning' the biofilter with the stocking density of 4.5 kg of fish $m^2$. The concentrations of ammonium-nitrogen, nitrite-nitrogen and nitrate-nitrogen in the system remained at the range of 0.096-0.315 mg/L, 0.015-0.504 mg/L, and 2.530-39.517 mg/L, respectively. Water temperature fluctuated from 17.5 to 25.1$^{\circ}C$ and salinity was from 30.1 to 33.5 ppt during rearing period. The fish grew from the average weight of 615.2 g to 1,201.1 g for 180 days. Initial and final fish densities were 8.4 and 15.9$kg/m^2$, Survival rate was 97.1 %. Neither parasites nor noticeable diseases was observed during the raring period even Vibrio spp. were detected from some fish in the system.

• Korean Journal of Food Science and Technology
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• v.44 no.3
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• pp.274-279
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• 2012

The objective of this study was to develop oral matrix tablets for the sustained release of vitamin C. In this study hydroxypropyl methylcellulose (HPMC) has been utilized as an excipient, as it is one of the most widely used polymers, for use during long periods of time in formations. The vitamin C tablet formulation depends on the molecular weight and concentration of sustained-delivery in HPMC. Anti-oxidants have been added as a dissolution medium in order to prevent vitamin C degradation in water. The dissolution test was carried out in a distilled water medium, and the release model equation was applied to analyze the vitamin C release pattern. The results demonstrated that the release and lasting power of vitamin C tablets, containing HPMC, lasted for more than 12 h.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.148-152
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• 2014

A mutant strain of Lactobacillus paracasei (ML-7) was derived by ultraviolet irradiation of the parent L. paracasei LS-2 strain, followed by colony selection on pH 3.5 MRS agar plates, on which L. paracasei LS-2 cannot grow. The L. paracasei ML-7 mutant strain produced an increased amount of organic acids compared to the L. paracasei LS-2 parent strain. Broiler chickens were randomly fed with one of three experimental diets: a basal diet as a control, and basal diets supplemented with 0.3% of the L. paracasei LS-2 and L. paracasei ML-7 strains. When concluding the study, the final body weights of the broilers fed with the supplemented basal diets were found to be significantly higher (1.9% for LS-2 and 6.2% for ML-7) than the control broiler group. Broilers fed with basal diet supplemented with the mutant L. paracasei ML-7 strain showed increased body weight and food intake, compared to broilers fed with the basal diet with or without the parent L. paracasei LS-2 strain.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.23-31
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• 2004

Normally, coating is used for protecting reinforced concrete. For this purpose, both organic and inorganic coatings are used. The advantages of inorganic coatings are lower absorption of UV, non-burning etc. On the other hand, organic coatings have the advantage of low permeability of $CO_2, SO_2$ and water. Organic coatings provide better protection for reinforced concrete. However, organic coatings such as epoxy, urethane and acryl reduce long-term adhesive strength by the difference of their thermal expansion coefficients and elastic modules from those of concrete, and the formed coating cover of these is blistered by poor breathing. Also, when organic coatings are applied to the wet surface of concrete, they have a problem with adhesion. In this study, a new coating material for protecting concrete was hybridized with polymer and ceramics. And tests were carried out on its physical and durable characteristics, and safety characteristic on elution. All results were compared with organic coating materials and epoxies and showed that the performance of the developed coating material was not inferior to that of other organic coatings in protecting concrete. On the other hand, safety characteristic on elution was superior to epoxies which were used in this study. So, the developed coating material was considered as a suitable protecting coating material which have advantages of inorganic and organic coatings for protecting underground concrete structures, especially in contact with water.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.4
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• pp.401-408
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• 2009

PME88 (gliadin-combined) melon superoxide dismutase (SOD) is known to promote the production of the body‘s own natural antioxidants including superoxide dismutase, catalase and glutathione peroxidase. In this study, we investigated the inhibitory effects of PME88 melonSOD on the ultraviolet-induced photo-aging by the evolution of minimal erythemal dose (MED), erythema quotation and spectrocolorimetric measurements of erythema. The analysis of the evolution of the MED showed a significant increase 28 days after the daily taken of the PME88 melonSOD. The analysis of the erythema quotation showed that on D29, for the dose 1.25 MED, erythema intensity is significantly higher for placebo group than for PME88 melonSOD group. At doses 0.64 MED$_{D14}$, 0.80 MED$_{D14}$ and 1 MED$_{D14}$ the value of parameter $a^*$ (the most sensitive to the colour changes bound to the variations of blood flow. It permits to assess the evolution of erythema) is significantly higher for placebo group. No significant difference has been observed between groups (PME88 melonSOD and placebo) on the evolution of the number and consistency of feces after 4 weeks of treatment. No intolerance has been observed during the 4 weeks of treatment. These results mean that PME88 melonSOD as a dietary supplement could be useful to attenuate ultraviolet-induced skin photo-aging.

• Analytical Science and Technology
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• v.16 no.1
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• pp.32-38
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• 2003

The rapid and sensitive determination method of sildenafil and its related compounds (Vardenafil, Homosildenafil, Tadanafil.) has been investigated using high performance thin layer choromatography (HPTLC). Optimizing separation conditions and simultaneous determination method of these compounds were studied. The calibration curves of those compounds at 254 nm was found to be linear in the range of $1.0{\sim}56.5{\mu}g/mL$, respectively. The detection limts (LOD) and quantification limits (LOQ) of these were found to be $0.8{\sim}1.8{\mu}g/mL$ and $1.0{\sim}2.3{\mu}g/mL$. The coefficient of variation (C.V.) were less than 2.5%. Finally, the present method was applied to determine sildenafil and its related substances in dietary supplement.

• Tribology and Lubricants
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• v.37 no.6
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• pp.232-239
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• 2021

Petroleum is the most consumed energy source in Korea with a usage rate of 38.7% among the available primary energy sources. The price of liquid petroleum products in Korea includes taxes such as transportation·environment·energy tax. Thus, illegal production and distribution of liquid petroleum is widespread because of its huge price difference from that of the normal product and its tax-free nature. Generally, the illegal petroleum product is produced by mixing liquid petroleum with other similar petroleum alternatives. The two kinds of gasoline, common gasoline and premium gasoline, are being distributed in Korea. The premium gasoline is often adulterated with cheaper common gasoline that lowers the octane number of gasoline. It is possible to distinguish them with their color difference, green and yellow for different grade gasoline. However, when small volume of common gasoline is added to premium gasoline, it is difficult to determine whether premium gasoline contained common grade or not. In this study, we inspect gasoline, which is illegally produced by mixing common gasoline to premium gasoline. When the ratio of mixing common gasoline is increased, premium gasoline shows decreasing absorbance at 600 nm and 650 nm under UV-Vis spectrometer. Moreover, the detected intensity (mV·s) of green dye in high performance liquid chromatography (HPLC) was decreased by common gasoline under 0.99 correlation value. The more the common gasoline is mixed, the more olefin and naphthene are detected by gas chromatography. In addition, trimethyl pentane as octane improver, paraffin and toluene are decreased by common gasoline mixing. The findings of this study suggests that illegal petroleum can be identified by analysis of components and simulated samples.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.125-133
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• 2011

The purpose of this study was to develop a methodology to detect spinosad which are difficult to analyze by multi-component simultaneous analysis of pesticide residues. We monitored spinosad due to the paucity of related information. The spinosad was determined using HPLC with UV detector at 250 nm. Correlation coefficient ($r^2$) for standard curve of spinosad A and D at standard concentration of 0.1-5.0 mg/kg were 0.999, respectively. Limit of quantitation (LOQ) of HPLC analysis was 0.005 mg/kg while limit of detection (LOD) was 0.001 mg/kg. Recovery experiments were conducted on five representative agricultural products to validate the analytical method. The recovery of proposed methods ranged from 74.9% to 104.0% and relative standard deviations were less than 10%. Spinosad residues were investigated in 16 commodities collected from 22 provinces. In this study, residues on all samples were not detected.