• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.434-442
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• 2017

The UV light in sunlight breaks down the chemical bonds in a polyolefin polymer through a process called photodegradation, ultimately causing cracking, chalking, colour changes, and loss of physical properties such as impact strength, tensile strength, elongation, and others. UV absorbers are used to prevent or terminate the oxidation of plastics by UV light. They are receptive to UV radiation and dissipate the energy harmlessly as heat. Benzotriazoles and benzophenones are used mainly in polyolefins such as polyethylene and polypropylene. In this study, we have developed a method for the analysis of 12 UV absorbers, which are Uvinul 3000, Cyasorb UV 24, Uvinul 3040, Tinuvin 312 and P, Seesorb 202, Chimassorb 81, Tinuvin 329, 234, 326, 328 and 327, migrated from the food packaging materials into four food simulants for aqueous, acidic, alcoholic and fatty foods. The UV absorbers in food simulants were determined by reversed-phase high performance liquid chromatograph-ultraviolet detector with 310 nm after solid-phase extraction with a hydrophilic-lipophilic balance (HLB) cartridge or dilution with isopropanol. The analytical method showed a good linearity of coefficient ($R^2{\geq}0.99$), limits of detection (0.049~0.370 mg/L), and limits of quantification (0.149~1.120 mg/L). The recoveries of UV absorbers spiked to four food simulants ranged from 70.05% to 110.13%. The developed method would be used as a reliable tool to determine concentrations of the migrated UV absorbers.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.664-671
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• 2017

Non-point source pollution is the emission source that unspecifically releases pollutants to water system from unspecific places such as cities, agricultural lands, mountains, and construction sites and its discharge path is not easily identified. Also, it is difficult to design and manage the reduction facilities for the emission quantity is primarily affected from weather conditions like rainfall. Since 2006, the significance of non-point source pollution reduction has been grown in Republic of Korea and this reinforces needs for the installation of reduction facilities. However, because the standards for the installation details and reduction efficiency are not clarified by law, people are preferring technologies that do not require particular maintenance and high expenses. The purpose of this study is to examine and maintain the efficiency of non-point source pollutants reduction facility which uses expended polypropylene as a media. The higher the depth of the media, the less range of variations in the reduction efficiency was observed and the final efficiency was also increased. When the media depth was 60 cm, the average reduction efficiency was 94% and 90% where linear velocities were 10 m/hr and 20 m/hr respectively. The results from 180 minutes operation in 10 m/hr and 20 m/hr of linear velocities were slightly different in head loss changes which were caused by media depth variations. The backwash experiments which were conducted in triplicate showed the reduction efficiency decreased as the time went on because of the media clogging. However, it was found that after the backwashing the reduction efficiency was increased as effective as the efficiency of the initial filtration.

• Food Science of Animal Resources
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• v.33 no.4
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• pp.531-541
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• 2013

This study was performed to investigate the antioxidant effect of Sansa (Crataegi fructus) extract in vitro, and to evaluate the functional effects of Sansa powder addition on the quality properties and storage characteristics of Tteokgalbi. Total polyphenol and flavonoid contents of Sansa extract were found to be 127.00 mg/g and 54.05 mg/g, respectively. The DPPH radical scavenging activity of Sansa extract was high and it was similar to the BHA and BHT. The Tteokgalbi was prepared by 0% (N), 0.1% (S1), 1% (S2), and 2% (S3) of the Sansa Powder. Addition of Sansa powder decreased the protein and lipid contents, but the ash content was significantly increased (p<0.05). Increasing the amount of Sansa powder in the pork Tteokgalbi tended to increase the water holding capacity (WHC) values and the cooking loss (p<0.05). The addition of Sansa powder increased the hardness and chewiness values, but did not affect the cohesiveness and springiness values. In the sensory evaluation, the S3 Tteokgalbi had the best score in color. Values of pH, total microbial counts, thiobarbituric acid (TBA) and volatile basic nitrogen (VBN) values decreased significantly added Sansa powder relative to the normal (p<0.05). The S3 Tteokgalbi was significantly (p<0.05) more effective for delaying lipid peroxidation than the other groups. Sansa powder addition increased the L (lightness) and a (redness) values. Therefore, the results demonstrate that adding the Sansa powder to the pork Tteokgalbi tended to improve antioxidative and antimicrobial effects during the chilled storage period.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.1
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• pp.13-24
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• 2006

Neuronal apoptotic events, consequently resulting in neuronal cell death, are occurred in hypoxic/ischemic condition. This cell death has been shown to be accompanied with the production of reactive oxygen species (ROS), which can attack cellular components such as nucleic acids, proteins and phospholipid. However, the underlying mechanisms of apoptosis induced in hypoxic/ischemic condition and its treatment methods are unsettled. Cobalt chloride $(CoCl_2)$ has been known to mimic hypoxic condition including the production of ROS. Epigallocatechin gallate (EGCG), a green tea polyphenol, has diverse pharmacologial activities in cell growth and death. This study was aimed to investigate the apoptotic mechanism by $CoCL_2$ and effects of EGCG on $CoCl_2-induced$ apoptosis in PC12 cells. Administration of $CoCl_2$ decreased cell survival in dose- and time-dependent manners and induced genomic DNA fragmentation. Treatment with $100{\mu}M$ EGCG for 30 min before PC12 cells were exposed to $150{\mu}M$ $CoCl_2$, being resulted in the cell viability and DNA fragmentation being rescued. $CoCl_2$ caused morphologic changes such as cell swelling and condensed nuclei whereas EGCG attenuated morphologic changes by $CoCl_2$. EGCG suppressed the apoptotic peak and a loss of ${\Delta}{\psi}_m$ induced by $CoCl_2$. $CoCl_2$ decreased Bcl-2 expression but Bax expression was not changed in $CoCl_2$- treated cells. EGCG attenuated the Bcl-2 underexpression by $CoCl_2$. $CoCl_2$ augumented the cytochrome c release from mitochondria into cytoplasm and increased caspase-8, -9 and caspase-3 activity a marker of the apoptotic executing stage. EGCG ameliorated the incruement in caspase-8, -9 and -3 activity, and cytochrome c release by $CoCl_2$ NAC (N-acetyl-cysteine), a scavenger of ROS, attenuated $CoCl_2-induced$ apoptosis in consistent with those of EGCG. These results suggest that $CoCl_2$ induces apoptotic cell death through both mitochondria- and death receptor-dependent pathway and EGCG has neuroprotective effects against $CoCl_2-induced$ apoptosis in PC12 cells.

• Progress in Medical Physics
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• v.13 no.3
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• pp.120-128
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• 2002

To investigate differences between the metabolic ratios of normal controls and brain tumors such as astrocytomas and glioblastoma multiforme (GM) by proton MR spectroscopy (MRS) at 37 high field system. Using 3T MRI/MRS system, localized water-suppressed single-voxel technique in patients with brain tumors was employed to evaluate spectra with peaks of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine/phosphocreatine (Cr) and lactate. On the basis of Cr, these peak areas were quantificated as a relative ratio. The variation of metabolites measurements of the designated region in 10 normal volunteers was less than 10%. Normal ranges of NAA/Cr and Cho/Cr ratios were 1.67$\pm$018 and 1.16$\pm$0.15, respectively. NAA/Cr ratio of all tumor tissues was significantly lower than that of the normal tissues (P=0.005). Cho/Cr ratio of glioblastoma multiforme was significantly higher than that of astrocytomas (P=0.001). Lactate was observed in all tumor cases. The present study demonstrated that the neuronal degradation or loss was observed in all tumor tissues. Higher grade of brain tumors was correlated with higher Cho/Cr ratio, indicating a significant dependence of Cho levels on malignancy of gliomas. This results suggest that clinical proton MR spectroscopy could be useful to predict tumor malignancy.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.169-174
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• 2008

Statement of problem: Changes of the marginal bone around dental implants have significance not only for the functional maintenance but also for the esthetic success of the implant. It was proposed that bone-retention elements such as microthreads at the coronal part of implant might help maintain the marginal bone level. Purpose: This study was designed to evaluate the effect of microthread configuration within the marginal coronal portion of the implant fixture at the marginal bone changes after loading around two different external hex implants. Material and methods: Twenty-four patients were included and randomly assigned to treatment with $Br{{\aa}}nemark$ system implants (Group 1, rough-surfaced implants, n=20) and Oneplant system implants (Group 2, rough-surfaced neck with microthreads, n=20). Clinical and radiographic examinations were conducted at baseline (implant loading) and 1 year postloading. Data analysis was performed by the SAS statistical package version 9.1.3 (SAS Institute, Cary, NC, USA) and the final model was calculated by the MIXED procedure (three-level ANCOVA) for marginal bone change of each test group at baseline and 1 year follow-up. Results: Comparing to baseline, significant differences were noted in marginal bone level changes for the 2 groups at 1 year follow-up (P<0.05). Group 1 had a mean crestal bone level changes of $0.83{\pm}0.31mm$; Group 2 had a mean crestal bone level changes of $0.44{\pm}0.36mm$. Rough-surfaced with microthreads implants showed significantly less marginal bone loss than rough surfaced neck without microthread implants. Conclusion: A rough surface with microthreads at the implant was beneficial design to maintain the marginal bone level against functional loading.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.44-52
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• 2010

The objective of this in vitro study was to detect and monitor demineralization and remineralization of primary teeth according to restorative materials using quantitative light-induced fluorescence (QLF). A single bur hole was drilled on the each sound forty eight primary anterior teeth, and the specimens were divided into three groups. The cavity was restored with $Filtek^{TM}$ Z250(Group 1), F2000(Group 2), $Ketac^{TM}$ N100(Group 3) following the manufacturer's instructions. The teeth were subjected to the demineralizing buffer for 3 days, and then subjected to a remineralizing buffer for 14 days. The change of mineral loss(${\Delta}Q$) according to the stages was evaluated by QLF and the following results were obtained: 1. When demineralization was done, ${\Delta}Q$ was increased as follows. : Group 1 ($-110.79\;{\pm}\;27.77$) < Group 2 ($-104.84\;{\pm}\;28.95$) < Group 3 ($-90.16\;{\pm}\;21.87$) : Resistance to demineralization was statistically significant in Group 3. 2. There was a statistically significant increase in ${\Delta}Q$ of all groups since 1st day of remineralization 3. The rate of remineralization, ${\Delta}$(${\Delta}Q$)/day, showed significant high value in each group on the 1st day then decreased rapidly. 4. There was no statistically significant difference in the degree of remineralization among restorative materials.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.217-225
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• 2004

This study was carried out to reduce the loss of frozen dough quality during frozen storage. Using response surface method, ascorbic acid 160.4 ppm, L-cysteine 63.1 ppm, and SSL 0.6% were found to be optimum, with xanthan gum 0.3% (formula A) and Ultra tex-3 5% (formula B) added as cryoprotectants. During frozen storage at $-20^{\circ}C$, control rapidly deteriorated after 4 weeks, while formulas A and B showed slight deterioration with immutable quality after 10 weeks.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.1
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• pp.19-26
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• 2017

Surface air temperature ($T_{air}$) is a key variable for the meteorology and climatology, and is a fundamental factor of the terrestrial ecosystem functions. Satellite remote sensing from the Moderate Resolution Imaging Spectroradiometer (MODIS) provides an opportunity to monitor the $T_{air}$. However, the several problems such as frequent cloud cover and mountainous region can result in substantial retrieval error and signal loss in MODIS $T_{air}$. In this study, satellite-based $T_{air}$ was estimated under both clear and cloudy sky conditions in Gangwon Province using Aqua MODIS07 temperature profile product (MYD07_L2) and GCOM-W1 Advanced Microwave Scanning Radiometer 2 (AMSR2) brightness temperature ($T_b$) at 37 GHz frequency, and was compared with the measurements from the Automated Mountain Meteorology Stations (AMOS). The application of ambient temperature lapse rate was performed to improve the retrieval accuracy in mountainous region, which showed the improvement of estimation accuracy approximately 4% of RMSE. A simple pixel-wise regression method combining synergetic information from MYD07_L2 $T_{air}$ and AMSR2 $T_b$ was applied to estimate surface $T_{air}$ for all sky conditions. The $T_{air}$ retrievals showed favorable agreement in comparison with AMOS data (r=0.80, RMSE=7.9K), though the underestimation was appeared in winter season. Substantial $T_{air}$ retrievals were estimated 61.4% (n=2,657) for cloudy sky conditions. The results presented in this study indicate that the satellite remote sensing can produce the surface $T_{air}$ at the complex mountainous region for all sky conditions.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.279-288
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• 2006

Three different experiments were undertaken to investigate the runoff and erosion loss of diazinon and metolachlor from sloped-field by rainfall. The mobility of two pesticides and which phase they were transported by were examined in adsorption study, the influence of rainfall pattern and slope degree on the pesticide losses were evaluated in simulated rainfall study, and the pesticide losses from soybean field comparing with bare soil were measured in field lysimeter study. Freundlich adsorption parameter (K) ranged $1.6{\sim}2.0$ for metolachlor and $4.0{\sim}5.5$ for diazinon. The K values of pesticides by the desorption method were higher than those ones by the adsorption method. Another parameter (1/n) in Freundlich equation for the pesticides tested ranged $0.96{\sim}1.02$ by desorption method and $0.87{\sim}1.02$ by adsorption method. By the SSLRC's classification for pesticide mobility of diazinon and metolachlor were classified as moderately mobile ($75{\leq}Koc$ <500). Runoff and erosion losses of pesticides by three rainfall scenarios were $0.5{\sim}1.0%$ and $0.1{\sim}0.7%$ for metolachlor and $0.1{\sim}0.6%$ and $0.1{\sim}0.2%$ for diazinon. Distribution of pesticides in soil polite were investigated after the simulated rainfall events. Metolachlor was leached to $10{\sim}15$ cm soil layer and diazinon was leached to $5{\sim}10$ cm soil layer. Losses of each pesticide in the 30% of sloping degree treatment were $0.2{\sim}1.9$ times higher than those ones in the 10% of sloping degree treatment. Pesticide losses from a series of lysimeter plots in sloped land by rainfall ranged $1.0{\sim}3.1%$ for metolachlor and $0.23{\sim}0.50%$ for diazinon, and were $1/3{\sim}2.5$ times to the ones in the simulated rainfall study. The erosion rates of pesticides from soybean-plots were $21{\sim}75%$ lower than the ones from bare soil plots. The peak runoff concentration in soybean-plots and bare soil plots were $1{\sim}9{\mu}gL^{-1}$ and $3{\sim}16{\mu}gL^{-1}$ for diazinon, $7{\sim}31{\mu}gL^{-1}$ and $5{\sim}40{\mu}gL^{-1}$ for metolachlor, respectively.