• Journal of Life Science
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• v.31 no.5
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• pp.488-495
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• 2021

The aim of this study was to investigate the possible antioxidant effect of Spirodela polyrhiza (SP) on rats fed a high fat and high cholesterol diet supplemented with either 5% (SPA group) or 10% (SPB group) SP for 4 weeks. The hepatic SOD activity of the HF group significantly decreased compared to that of the N group, but that of the SPA and SPB groups significantly increased. The GPx activity of the SPA and SPB groups in the liver was significantly greater than that of the HF group, and the hepatic catalase activity of the SPA and SPB groups significantly increased compared to the HF group. The hepatic superoxide radical content of the mitochondria and microsomes of the HF group significantly increased compared to that of the N group, but the contents were reduced in the group that took SP powder. The hepatic hydrogen peroxide content in the cytosol and mitochondria of the SP powder group was lower than in the HF group. The carbonyl content in the mitochondria and microsomes of the SPA and SPB groups was significantly lower than in the HF group. The TBARS values in the liver significantly decreased in the SPA and SPB groups. Spirodela polyrhiza was thus effective in reducing oxidative stress by regulating the hepatic antioxidant enzymes and the free radicals in rats fed high fat and high cholesterol diets.

• Journal of Life Science
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• v.22 no.7
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• pp.889-896
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• 2012

Melanin synthesis is catalyzed by tyrosinase. To investigate the whitening effect of Hizikia fusiformis, fractions from ethanol extract of H. fusiformis were prepared by a systematic fractionation procedure with solvents such as methanol, hexane, butanol, and $H_2O$. The ethanol extract and its fractions were then subjected to evaluate the inhibitory effects on the tyrosinase activity and melanin synthesis in murine B16F10 melanoma cells. The ethanol extract and aqueous fraction exhibited a whitening effect with no cytotoxicity. The ethanol extract showed the highest whitening effect among the samples. The inhibitory effect of $100{\mu}g/ml$ of ethanol extract was higher than that of $10{\mu}g/ml$ of arbutin, but it was lower than that of $10{\mu}g/ml$ of kojic acid. Furthermore, the inhibitory effects of $100{\mu}g/ml$ of methanol, hexane, butanol, and aqueous fractions were similar to those of $10{\mu}g/ml$ of arbutin. The antioxidant activities were examined by comparing the results with that of ascorbic acid as a positive control. The ethanol extract and aqueous fraction showed relatively higher DPPH radical-scavenging activities compared with the other samples. Furthermore, $500{\mu}g/ml$ of ethanol extract and aqueous fraction diminished LPS-induced iNOS expression to 82 and 80%, respectively. These results suggest that ethanol extract and aqueous fraction of H. fusiformis could be used as cosmetic ingredients for whitening and skin protection effects.

• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.197-202
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• 2009

The long term stability of ion current of QMS has been one of key parameters for monitoring gas process in vacuum. The time dependence of ionic current was monitored while the pressure of nitrogen gas was kept at a fixed pressure by introducing the gas into vacuum chamber. The chamber was evacuated to ${\sim}3{\times}10^{-9}\;Torr$ to reduce background signals before the measurement. Two ion sources were tested; one had brownish or black color due to gas contamination and the other one was new, i.e. cleaner. At a nitrogen pressure of $1{\times}10^{-5}\;Torr$, the ionic currents measured by the contaminated ion source decreased faster with time. The decrease rate was respectively ${\sim}46%$ for cleaner one and ${\sim}84%$ for contaminated one after ${\sim}5.5%$ hours. In order to test the effect of filament material on the ion current decrease, we fabricated a tungsten(W) filament which consisted of two parts; one half was made of W and the other was coated with yttria. The similar decrease of ionic currents were shown for the two types of filaments, indicating that slight change of temperature of filament due to material difference i.e. baking effect could not improve the origin of ionic current decrease. Overall the decreasing rate of ionic current is more closely associated with contaminated ion source of QMS rather than its filament materials.

• Advances in pediatric surgery
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• v.12 no.1
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• pp.70-85
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• 2006

A nationwide survey on necrotizing enterocolitis (NEC) was undertaken among members of the Korean Association of Pediatric Surgeons. The members were required to complete a questionnaire and the case registration form for each patient during the three-year period from July 2001 to June 2004. Eighty one patients were included in the questionnaire, but only 71 patients were registered from 22 members in 16 hospitals. At the same time survey on focal intestinal perforation (FIP) was undertaken and 17 patients were registered from 11 members in 10 hospitals. Total 19,041 newborns were admitted to neonatal intensive care unit during the study period. Eighty one patients (17.27 %) were underwent surgery among 469 babies who were managed under the impression of NEC. The male to female ratio was 2.1:1. The premature were 60.6 %. The most common site of involvement was ileum. Overall and operation survival of NEC were 72 % and 79 %, respectively. The survival was lower in smaller babies, multiple segments involvement and involvement of both the small and large intestine. But there was no difference in survival according to sex or prematurity. The FIP showed very similarity with NEC in terms of incidence, and the age of diagnosis and operation. But the survival was much better and 100 %. The results showed the clinical characteristics of NEC and the trend of management in NEC in Korea. In the future we hope we can discuss about this topic in prospective manner.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.501-510
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• 2015

In this study, we investigated the onset and release of endo-dormancy under natural conditions by observing bud break characteristics in 'Fuji' apple trees using water cuttings. Through examinations of bud break rate and days to bud break, we found that the endo-dormancy of 'Fuji' apple tree continues for 70 d from 165 to 255 d after full bloom (DAFB), from late October to early January of the following year. In addition, within 20 d of first bud break, based on a final bud break rate of 60% or more, we able to identify the timing of the changeover from para-dormancy to endo-dormancy, and endo-dormancy to eco-dormancy. Analysis of the chilling requirement during the endo-dormancy period revealed that chilling accumulation up to 255 DAFB to release endo-dormancy amounted to 666 and 517 h based on the CH and Utah models, respectively. Observation of internal changes in the bud during endo-dormancy showed that flower bud differentiation begins from mid-July, and t ime of inflorescence o f the disk f lower is a vailable to f ind. The f lower buds subsequently developed slowly but steadily during endo-dormancy and in the following year in February, the developmental stage of each organ had progressed. Moreover, the flower buds of 'Fuji' apples were mostly healthy during the dormancy period, but some exhibited necrosis of flower primordium, due partial cell damage from the formation of ice crystals rather than a direct effect of the low temperature. Flower buds were formed in both the axillary buds of bourse shoots and terminal buds of spurs, but lower bud differentiation was observed for the terminal buds of spurs at rate of about 65% of total buds, which was directly related to the bud size and shoot diameter.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.8
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• pp.870-876
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• 2005

The multiple regression models which have two factors(population and commercial area) have been used to forecast the water demand in the future. But, the coefficient of population had a negative value because proper regional classification wasn't performed, and it is not reasonable because the population must be a positive factor. So, the regional classification was performed by principal component and cluster analysis to solve the problem. 6 regional characters were transformed into 4 principal components, and the areas were divided into two groups according to cluster analysis which had 4 principal components. The new regression models were made by each group, and the problem was solved. And, the future water demands were estimated by three scenarios(Active, moderate, and passive one). The increase of water demand ore $89.034\;m^3/day$ in active plat $49,077\;m^3/day$ in moderate plan, and $19,996\;m^3/day$ in passive plan. The water supply ability as scenarios is enough in water treatment plant, however, 2 reservoirs among 4 reservoirs don't have enough retention time in all scenarios.

• Korean Journal of Weed Science
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• v.8 no.3
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• pp.273-282
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• 1988

The seventeen barnyardgrass [Echinochloa crus-galli (L.) Beauv.] accessions, which were collected national-widely in 1986 and selected two times through 1987, were experimented at 1988. To study the degree of ecological variations of the collected accessions of native barngardgrass species as a weed, the experiment was conducted with Wagner pots in size of 1/5000a and under P.E. film house. Among 57 characters, 100 grains weight, rate of tiller increase from transplanting to 30 days, the number of the maximum tillers and rate of dry weight increase from 15 DAS to 22 DAS were become intra-specific variarions as higher coefficient of varation than 30%, the size of the first leaf, fresh weight and dry 22 seedlings, rate of productive tiller, panicle number and tillering divergence made intra-specific variations as more and less C. V. than 25%, while the required days upto heading since seeding at June 6. rate of fresh/dry weight and plant height of 22 days old seedling made intra-specific variations as the coefficient of variation of about 50%. Among the attributes the color in leaf, leaf sheath, mid-ribs, node, spike, grain, and plant type, length of leaf marginal tooth, grain shape, purple bend on leaf were seemed useful to indentify the accessible specific.

• Tuberculosis and Respiratory Diseases
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• v.46 no.4
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• pp.564-573
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• 1999

Background: With variable symptoms and nonspecific radiographic appearances, pulmonary embolism (PE) is a frequent and often undiagnosed cause of mortality and morbidity. The Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study suggested that the majority of patients undergoing ventilation-perfusion (V-Q) scan would require additional studies to establish or to exclude the diagnosis of PE. Pulmonary angiography has been regarded as gold standard for diagnosis of PE. However, it is an invasive procedure that may be associated with significant notable morbidity and mortality. Thus, availability of an accurate, noninvasive screening examination is highly desirable. Method: From October 1994 to February 1997, twenty patients (male 13, female 7, range 23-91 years, median 58 years) who were suspected as pulmonary embolism on the basis of clinical evidence and underwent the spiral volumetric computed tomography (spiral CT), were studied retrospectively to evaluate the effectiveness of spiral CT as a diagnostic tool in PE. Results: PE could be excluded with spiral CT in 4 patients ; diagnoses of these patients were lung cancer, pneumonia with lung abscess, bilateral pleural effusion due to congestive heart failure, nonspecific pulmonary abnormality retrospectively. One patient who disclosed high probability in V/Q scan, could be diagnosed as pneumonia with lung abscess and underlying emphysema with spiral CT. Among 4 patients who showed intermediate and low probability in V/Q scan, 3 patients could be confirmed as PE with spiral CT. Spiral CT was helpful in 3 patients, in whom V/Q scan could not be performed due to other reasons (e.g. night time, mechanical ventilation) to confirm the diagnosis of PE. Spiral CT could demonstrate embolus above lobar artery level in 11 patients, and up to segmental artery level in 5 patients. Conclusion: This study demonstrated that spiral CT could allow accurate demonstration of thrombotic clots in centrally localized embolism. Spiral CT could be effective, specific, noninvasive and useful diagnostic screening modality for the diagnosis of pulmonary embolism.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.61-66
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• 2012

Chemical Mechanical Planarization (CMP) is a polishing process used in the microelectronic fabrication industries to achieve a globally planar wafer surface for the manufacturing of integrated circuits. Pad conditioning plays an important role in the CMP process to maintain a material removal rate (MRR) and its uniformity. For metal CMP process, highly acidic slurry containing strong oxidizer is being used. It would affect the conditioner surface which normally made of metal such as Nickel and its alloy. If conditioner surface is corroded, diamonds on the conditioner surface would be fallen out from the surface. Because of this phenomenon, not only life time of conditioners is decreased, but also more scratches are generated. To protect the conditioners from corrosion, thin organic film deposition on the metal surface is suggested without requiring current conditioner manufacturing process. To prepare the anti-corrosion film on metal conditioner surface, vapor SAM (self-assembled monolayer) and FC (Fluorocarbon) -CVD (SRN-504, Sorona, Korea) films were prepared on both nickel and nickel alloy surfaces. Vapor SAM method was used for SAM deposition using both Dodecanethiol (DT) and Perfluoroctyltrichloro silane (FOTS). FC films were prepared in different thickness of 10 nm, 50 nm and 100 nm on conditioner surfaces. Electrochemical analysis such as potentiodynamic polarization and impedance, and contact angle measurements were carried out to evaluate the coating characteristics. Impedance data was analyzed by an electrical equivalent circuit model. The observed contact angle is higher than 90o after thin film deposition, which confirms that the coatings deposited on the surfaces are densely packed. The results of potentiodynamic polarization and the impedance show that modified surfaces have better performance than bare metal surfaces which could be applied to increase the life time and reliability of conditioner during W CMP.

• The Korean Journal of Air & Space Law and Policy
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• v.23 no.2
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• pp.173-205
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• 2008

Space debris have frequently caused damage to space objects like satellites in orbits and sometimes have fallen on the earth. Such increase in space debris will lead to the high possibility of threatening space activities of mankind. However, it is not so easy for the damage caused both by identified and by unidentified space debris to be recovered since in the regime of the current international law, there is no legislation of prescribing the damage done by space debris. For overcoming the limitation it seems desirable that either the Liability Convention should partly be amended or new international law regime should be established. For instance, 'space debris' should be included in the new definition of 'space object' and the range of launching should also be defined clearly by making the concept of 'launching' somewhat more specified. Moreover, the subject of international liability for damage caused by space debris should be divided into two classes: the subject before and after registration. While in case of before-registration launch states should be held liable for any damage jointly or individually, in case of after-registration 'the state of registry' or 'owner' of the space debris should be. In the event of damage being caused elsewhere than on the surface of the earth to a space object of other State, 'fault-based liability' is currently applied. But it needs to be changed into 'absolutely liability'. In this paper, 'Liability Pool', 'Insurance', 'Market-Share Liability' are presented as aid devices of the damages resulting from unidentified space debris. They should be defined through the amendment of the Liability Convention or another international treaty. Some day there comes a time when our country shall possess many of the astronomical price of satellites. It means that we can't be free from the damage by the increasing number of space debris. Provided that our satellites are damaged by such space debris, it will do the satellites damage and cause impaired functioning or troubles in operation. As a result, if we are not paid for the damage by space debris, we will be confronted with tremendous economic loss because it is necessarily connected with the excess burden of taxation. Thus, an international agreement regarding the measures of the compensation for space debris damage must be made very soon.