• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.839-846
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• 2008

The flocculation characteristics of polyacrylamide base flocculants were estimated to reduce the moisture content of the dehydrated cakes. The dewaterability for sewage sludge was found to have a marked effect depending on the flocculant type, agitating speed and time, kind of dissolution water, etc. The optimal agitating speed and time were 700 rpm and 3 sec, respectively, in this experimental condition. and the dewaterability was proportion to the agitating speed upto 700rpm. When recycle water as the dissolution water was used, the solution viscosity of all kind of flocculants was decreased. However, the change of its viscosity are not proportioned to the dewaterabilities for each flocculant. Flocculation system of combinations of the first and sencond flocculation using single flocculant was investigated. Effects of the ratio of first and second dosage for dual flocculation on the dewaterability were also investigated. The optimum conditions of dual flocculation system are 75% and 50% as first dosages for low and high viscous flocculant for total dosage of common flocculation, respectively. Based on the results, an overall mechanism of dual flocculation system is proposed and it is envisaged that optimization of flocculation processes in this way can result in considerable savings in cost.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.829-839
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• 2003

Recently, the corrosion of reinforced concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the influences of carbonation to chloride attack in concrete structures. The test results indicate that the chloride penetration is more pronounced than the case of single chloride attack when the carbonation process is combined with the chloride attack. It is supposed that the chloride ion concentration of carbonation region is higher than the sound region because of the separation of fixed salts. Though the use of fly ash pronounces the chloride ion concentration in surface, amounts of chloride ion penetration into deep region decreases with the use of fly ash. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of both chlorides and carbonation but the future studies for combined environment will assure the precise assessment.

• Journal of Life Science
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• v.16 no.5
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• pp.834-839
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• 2006

This study was carried out to investigate changes in cell wall components and solubilization and depolymerization of pectin and neutral sugar polymers during softening of 'Tsugaru' apples. Pectic polysaccharides were solubilized in different solvents, distilled-water, 0.05 M CDTA, 0.05 M $Na_2CO_3$, and 8 M KOH, from cell wall materials during fruit softening. The uronic acid contents in distilled-water fraction rapidly increased along with fruit softening at 4 weeks after ambient storage. In the change of non-cellulosic neutral sugars in the cell wall of ‘Tsugaru’ fruits, the major sugar was galactose and arabinose in distilled-water, 0.05 M CDTA and 0.05 M $Na_2CO_3$ soluble fractions, and it was glucose, galactose and xylose in 8 M KOH fraction. Especially the change of galactose contents in distilled-water fraction was increased greatly along with fruit softening. When uronic acid polymers (UAP) and carbohydrate polymers (CP) in distilled-water fraction were filtered and separated using Sepharose CL-2B column, the high molecular UAP and CP were degraded to the low molecular ones from at harvest to softening fruit. Thus, the amount of high molecular polymers were greatly decreased along with fruit softening.

• Korean journal of food and cookery science
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• v.30 no.5
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• pp.540-546
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• 2014

This study was conducted to compare the commercial noodle flours (n=8) of each milling company in Korea. Eight noodle flour samples were classified into two types of flours, all-purpose flour (AF, n=4) and premium noodle flour (PF, n=4) and tested using general component analysis. Texture assessment and sensory test for doughs and noodles were performed. The dough strength was positively correlated with lower ash content, smaller particle size and longer formation time. Sensory evaluation found that weaker cooked noodle strength correlated with higher scores in preference and softness. As a result, it can be suggested that PF is better than AF in noodle making because PF has lower ash content and smaller particle size than AF. As such, flour characteristics that produce noodle flour of uniform quality can be obtained by combining flours with the above processing characteristics to fit the qualities desired.

• Journal of Korean society of Dental Hygiene
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• v.10 no.5
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• pp.831-839
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• 2010

Objectives : The purpose of this study was to examine dental hygiene students' image of dental hygienist and factors affecting the image of dental hygienist in an effort to provide some information useful for dental hygiene education. It's basically meant to recreate the image of dental hygienist as a professional. Methods : The subjects in this study were 310 sophomores and seniors who ere selected by convenience sampling from three different three-year-course colleges located in Gyeonggi Province, Chungcheong Province and Gwangju. After a survey was conducted, the answer sheets from 277 respondents were analyzed except for 33 incomplete ones. The collected data were analyzed with a SPSSWIN 17.0 program, and statistical data on frequency and percentage were obtained to find out the general characteristics of the subjects, and another statistical data on mean and standard deviation for each item were acquired to check their image of dental hygienist. Besides, t-test, ANOVA and Kruscal-Wallis test, one of nonparametric test, were utilized to look for connections between their general characteristics and image of dental hygienist. Results : 1. They gave a mean of 3.53 to the image of dental hygienist, which showed that the dental hygiene students took a favorable view of dental hygienists in general. 2. Their response to four items showed that they looked at the image of dental hygienist in a positive manner. The four items respectively described dental hygienists as professionals, as ones who played a crucial role in the improvement of national oral health, as ones with professional knowledge and sophisticated knowhow, and as neat and decent people. And their response to the following five items indicated that they looked at the image of dental hygienists in a negative way. One was that dental hygienists were considered to be dental nurses, and another was that the occupation of dental hygienist was a demanding and stressful job. The third was that there was no single, fixed title to call dental hygienists, and the fourth was that dental hygiene wasn't recognized as an independent area. The fifth was that the social standing of dental hygienists was sort of high. 3. In regard to the impact of the general characteristics of the dental hygiene students on their image of dental hygienist, they had a more favorable image of dental hygienist when they perceived dental hygiene in a more positive manner(p<0.001). Conclusions : In order to boost the image of dental hygienist, the working conditions of dental hygienists should be improved, and educational programs should be prepared to provided them extended continuing educational opportunities. And the kind of educational environments that could nurture dental hygienists who are convinced and have a vision should be created.

• Journal of Life Science
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• v.27 no.7
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• pp.834-839
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• 2017

Propolis is a natural product collected from plants by honey bees product used extensively in traditional medicine for its antioxidant, anti-inflammatory, immunomodulatory and anti-cancer effects. Propolis exhibits a broad spectrum of biological activities because it is a complex mixture of natural substances. Ovarian cancer is the second most common newly diagnosed cancer from all cancers among women in Korea and the leading cause of death from gynecological malignancies. While most ovarian cancer patients initially respond to surgical debulking and chemotherapy, patients later succumb to the disease. Thus, there is an urgent need to test novel therapeutic agents to counteract the high mortality rate associated with ovarian cancer. In this study, we investigated the anti-cancer properties and the active mechanism of Australian propolis in human epithelial ovarian cancer A2780 cells. Our data revealed that propolis showed a cytotoxic activity in a dose-dependent manner. Flow cytometric analysis for cell cycle arrest and apoptosis using propidium iodide staning and annexin V-FITC indicated that propolis could induce cycle arrest in the G0/G1 phase and apoptosis in a dose-dependent manner on human epithelial ovarian cancer cells. These results suggest that the Australian propolis is potential alternative agent on ovarian cancer prevention and treatment.

• Korean journal of applied entomology
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• v.20 no.3 s.48
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• pp.173-175
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• 1981

New screening method of varietal resistance by isotope $^{32}P$ was examined in these experiments. Insects were fed for 24 hrs. in the vials, with rice seedlings absorbed the solution if $0.6\~7{\mu}\;Ci\;^{32}P$ for 24 to 48 hrs. Feeding amounts of 3 species of plant-hoppers at the different stages and duration of infestation were investigated for effective process of screening method of the varietal resistance using isotope $^{32}P$. Feeding amount of $^{32}P$ of brown plant-hopper was observed for the different varieties. The results may be summarized as follows: 1. Brown planthopper fed greatest and the feeding amount were increased in order of white-backed planthopper and small brown planthopper. Female hoppers fed more than male. 2. Feeding amount was increased in order of adult, 5th instar, adult, 4th instar, 3rd instar 2nd instar and 1st instar. The duration of $24\~48\;hours$ is considered sufficient for insect infestation. 3. New screening method by $^{32}P$ was compared with seedling bulk screening method in view of feeding amount and plant reaction. Feeding amount of $^{32}P$ by brown planthopper in Milyang 47, resistant variety to this insect, was very low, while in TN 1, susceptible variety, it was very high about one hundred tines of Milyang 47.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.5
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• pp.839-845
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• 1996

To investigate effects of Jujube methanol extract on the carbon tetrachloride-induced liver damage in rats, experimental animals were divided into 4 groups; control group(CON), Jujube methanol extracttreated group(JME), $CCl_4$- treated groups(CCl), and Jujube methanol extract and $CCl_4$-treated group (JMC). Each group was sacrificed after 2 or 4week feeding and determined the activities of serum transaminase(GOT, GPT) and hepatic xanthine oxidase, superoxide dismutase(SOD), catalase and glutathione peroxidase(GSH-Px), and hepatic contents of thiobarbituric acid-reactants(TBARS) and glutathione in liver. The activities of sGOT and sGPT, and the hepatic content of TBARS after $CCl_4$-treatment were markedly increased, compared to CON, but those levels were significantly decreased by the pretreatment of Jujube methanol extract, especially in sGOT after 2 and 4 week and TBARS after 4week respectively. Xanthine oxidase activity was increased by $CCl_4$- treatment as compared to CON, but it was also inhibited by the pretreatment of Jujube methanol extract for 2 and 4 week. The activities of SOD, catalase and GSH-Px were elevated by $CCl_4$-treatment, compared to CON, but those elevated activities were showed significant decreasing effect by pretreatment of Jujube methanol extract after 2 and 4week as compared to CON, however, hepatic catalase activity was not affected significantly. These results suggest that Jujube methanol extract is believed to be a possible protective effect for the carbon tetrachloride-induced hepatotoxicity in rats.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.839-848
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• 2007

Purpose: Various kinds of biodegradable membranes are currently used in dental clinics. And the frequency and the necessity of their usage are increasing due to their numerous advantages. Therefore it is important to understand the difference of various membranes and histological reaction against implanted membranes. Materials and Methods: Biodegradable membranes of $Biogide^{(R)}$, $Resolute^{(R)}$, and $Tutodent^{(R)}$ were cut into small pieces by $1.0{\times}0.5cm$. The membranes were implanted 1.5cm apart from each other under the epithelium on the skull of 18 Sprague Dawley rats. The animals were sacrificed at 3, 7, and 14 days after surgical procedure. The specimens were examined by histological analysis. Results: 1. Early period after implantation of the membranes showed connective tissues surrounding membranes and there were a few inflammatory cells present. 2. In $Biogide^{(R)}$ and $Tutodent^{(R)}$ specimens, inflammatory cells and surrounding tissues were shown to infiltrate from outside with slight density difference inside. In $Resolute^{(R)}$ specimens, membranes were fragmented. Inflammatory cells and connective tissues were also observed inside. 3. In $Resolute^{(R)}$ specimen, giant cells were present which implicates that foreign body reaction has occurred. 4. $Biogide^{(R)}$ had lower integrity than other membranes and is not enough to be used alone in defect area. However, $Resolute^{(R)}$ had superior firmness than others. $Tutodent^{(R)}$ had middle level of integrity. Conclusion: This experimental model enabled to observe early inflammatory reactions and morphological changes of materials and can be used to develop and evaluate the efficacy of biodegradable membranes. Duplication of standardized human oral environment will be required in future experiments.

• Korean Journal of Veterinary Research
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• v.36 no.4
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• pp.839-844
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• 1996

This study was designed to investigated the effects of cadmium(Cd) feeding on the humoral immune responses such as PFC-responses and production of immunoglobulins in BALB/c mice. The results obtained were summarized as follows; 1. Total PFCs of direct IgM antibody response were significantly decreased in all Cd-fed goups, whereas total PFCs of IgG antibody response were slightly increased. 2. In secondary immunization, total HA titers were increased in all Cd groups as compared with control, especially in 100ppmm group and also IgG titers were slightly increased except for 50ppm group. 3. The levels of $IgG_1$ were increased to 5.5% 18.7%, 17.4% and 7.2% in 25, 50, 100 and 200ppm groups as compared with control, respectively. And also the levels of IgE were increased to 5.7%, 7.3%, 8.7% and 0.4% in those of Cd groups, in order. Conclusively, concentrations of $IgG_1$, and IgE were increased in all Cd groups. Based on the results of this study and previous report, it was shown that Cd might affect humoral immune responses by modifying the distribution and function of cells playing in the cellular immune response.