• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.214-234
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• 1995

The purpose of this work was to study the compatibility of several commercially available dentin adhesives with composite resins. In this study, V-shaped cavity preparations were created on both buccal and lingual surfaces of 60 extracted human premolars($3mm{\times}3mm{\times}2mm$ deep). Preparations were located such that the occlusal margins were on the enamel and the gingival margins were on the cementum(1mm below the CEJ). These specimens were randomly divided into three equal groups. Three dentin adhesives(Scotchbond Multi-Purpose, All Bond 2, Prisma Universal Bond 3)were applied to the cavity in accordance with each manufacturer's instructions. The teeth in each group were restored with four composite resins(Silux plus, Z100, Bisfil, Prisma TPH) in three increments, with each increment light-cured for 40 seconds. All specimens were exposed to 500 cycles of thermal stress. Specimens then placed in a silver nitrate solution(50% by weight) and stored in darkness for 24 hours. They were then immersed for 6 hours in photographic developing solution under flourescent light. Specimens were sectioned buccolingually through the center of the restoration and observed under a binocular stereoscope. To compare the marginal leakage, ANOVA and Dunkan's multiple range tests were used in analysis. Selected samples were further studied using scanning electron microscopy(XL20, Philips, The Netherlands). The results were as follows. 1. In all groups, the enamel margin showed significantly less leakage than the cementum margin. 2. No statistically significant differences were found in microleakage when composite resins were used with their proprietary dentin adhesives. 3. In comparison between dentin adhesives, Prisma Universal Bond 3 showed significantly less leakage at the enamel margin and Scotch bond multi-purpose showed significantly less leakage at the cementum margin than the other groups. 4. In comparison between composite resins, Silux Plus showed significantly more leakage than other groups at the enamel margin and no statistically significant differences were found in microleakage at the cementum margin. 5. According to the backscattered scanning electron microscope, microleakage occurred via gaps at the dentin adhesives/dentin interface.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1142-1150
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• 2009

In this paper, we propose an novel bandwidth scheduling algorithm for the MAC protocol employed by the Data Over Cable Service Interface Specifications (DOCSIS) 3.0 compliant cable networks. The proposed algorithm statistically improves the chances of request piggybacking to minimize the access delay. It utilizes the piggyback request feature of the segment packets that has been newly specified in DCOSIS 3.0. In DOCSIS 3.0, a bandwidth request can be granted to several upstream channels within an upstream bonding group. The grant on each individual channel is treated as a segment packet. We find the optimal segment placement to minimize the access delay in the proposed algorithm. We also use a self-similar traffic model for simulation and analysis to evaluate the performance of the proposed algorithm.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.267-275
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• 2015

This study has been implemented to check the effect of roughness on the color stability according to the surface treatment of artificial teeth. 20 units of 3 groups with the different surface treatment of artificial teeth have been precipitated in the soy sauce, the red pepper paste, the coffee and the cola, measure equipment was used for Shade-eye(Chroma Meter, Shofu, U.S.A). The value of L*, a*, b* using its average value after measuring 3 times per 1 point by selecting 3 points randomly out of central parts of teeth on a cycle of each 1 day, 1 week, 2 weeks, 3 weeks, 4 weeks after precipitation in terms of precipitated specimens. As a result of Multiple regression analysis, the value of ${\Delta}E*$ of artificial teeth according to the surface treatment showed the significant negative(-) effect in the Group 2(p<0.001) and the red pepper paste had the biggest effect on the color change of artificial teeth out of pollution source.

• Journal of Korean society of Dental Hygiene
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• v.17 no.3
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• pp.527-537
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• 2017

Objectives: The purpose of this study was to examine the practice of oral hygiene behaviors and oral health status of long-term care facility residents and to analyze the factors related to salivary hemoglobin level which can predict active periodontal disease. Methods: From 30th October 2015 to 7th January 2016, a questionnaire was provided to 63 participants and their dental plaque and saliva samples were collected to assess the levels of salivary hemoglobin and dental plaque acidogenicity. In order to analyze the factors related to salivary hemoglobin level, multiple linear regression analysis was performed. Results: Toothbrushing was most frequently performed by the participants themselves (98.4%) and toothbrushing was performed after eating breakfast (81.3%). 68.8% of participants reported brushing their tongue. 35.9% of participants perceived having bad teeth, and 87.5% had high dental caries activity. The percentages of participants with hyposalivation and ${\geq}0.20{\mu}g/ml$ salivary hemoglobin level were 45.3% and 59.4%, respectively. The salivary hemoglobin level was significantly higher in the group in which stimulated salivary flow rate was ${\leq}0.70ml/min$, dental plaque acidogenicity was superior, and perceived having bad teeth (p<0.05). There was also a tendency for the salivary hemoglobin level to increase with age (p<0.05). Conclusions: Oral health status of the long-term care facility residents was still not improved, and the characteristics of salivary volume and dental plaque were important factors affecting salivary hemoglobin level. Therefore, it is necessary to operate an oral hygiene intervention program by oral health professionals in such facilities in order to provide residents with effective oral care aligned with their respective needs. Furthermore, it is necessary for caregivers to complete mandatory oral health education to improve the oral hygiene status of the long-term care facility residents.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2009.04a
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• pp.23-28
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• 2009

The purpose of this study was to improve not only wet-end performances but also paper characteristics by the modification of various factors like molecular design and ionic characteristics of polyacrylamides First of all physical characteristics were observed after modify molecular design of the cationic polyacrylamides to linear, branched and cross-linked. In addition it was found analysis method to confirm branch degree of cationic polyacrylamides to combine ionic titration characteristics and spectroscopic behavior, After application of these structure modified polyacrylamides to the multiple retention systems with inorganic microparticles, it was found adjusting of branch degree of polyacrylamides was very important to optimize wet-end improvement. Second, After polymerization of amphoteric polyacrylamide to have both of cationic and anionic functional group in the polymer, we observed not only physical characteristics but also wet-end improvement to apply recycled pulp and found that the improvement of solution stability to prevent hydrolysis and increase of ash retention dramatically to compare traditional cationic polyacrylamide retention aid, Finally, After polymerization of anionic polyacrylamide, we observed not only wet-end improvement but also paper characteristics to apply preflocculation of PCC and it was found the improvements of flocculation efficiency, retention, ash retention, optical properties of the paper and bursting strength to compare traditional preflocculant of cationic polyacrylamide.

• Journal of Preventive Medicine and Public Health
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• v.40 no.5
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• pp.345-350
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• 2007

Objectives: To determine the disparity in the rate people undergo health examinations according to socioeconomic position (SEP) and the changes in this disparity with time. Methods: Seoul citizens' health profile data from 1997 to 2005 were analyzed. The study subjects were 40 years old and over, and the total number of subjects was 6,601 in 1997, 8,994 in 2001, and 8,819 in 2005. Those aged 60 years and over were eliminated from the analysis of subjects' occupation. We used education, family income and occupation as indicators of SEP. The age-standardized health examination attendance rate for each year was calculated according to the education, family income and occupation. The odds ratios (ORs) from multiple logistic regressions were adjusted for age. Results: The disparity in the rate of attendance according to the SEP decreased from 1997 to 2005 but still existed. Even though the disparities among the subgroups according to education, family income and occupation were not that high, the disparity between the group with the highest SEP and the other groups was considerable. Conclusions: Our findings suggest that unequal access to health examination services according to socioeconomic position still exists. This disparity has decreased recently but the disparity according to level of education was the greatest.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.5
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• pp.701-712
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• 2004

This study is aimed at the application of the apparel size system to be applied for the Internet shopping mall in Korea. Especially this is focused on the presumption of the body measurement according to the age groups and the figure groups. In this regard, a sizing system is to be developed that could be used to approach consumers more easily and provide more fitness and accuracy in terms of size. The target study was on a group of women nineteen to forty-nine years of age. The 4th National Anthropometry Survey data were used in the examination. The results in the study are as follows ; (1) On the Internet apparel shopping malls in relation with this study, no matter what size in the ready-to-wear enterprises was selected by the consumers who once put their information in the member registration, the most appropriate sizes for them are automatically given and transferred to the order forms of chosen enterprises with aid of internal programs of the internet webpage. In addition, when consumers enter their body sizes in the units that are familiar to them, such as inches or centimeters, the units are automatically programed so that they can be converted for the sake of convenience. ; (2) To extract an estimation equation of body size through Multiple Regression Analysis, the circumferences of chest and hip could be presumed by stature, weight, and waist circumference of which most consumers were well aware. For more accurate regression equations, groupings were made in the three categories of age(19∼29/30∼39/40∼49) and in the three body types(Type N, A and H). Then, the regression equations were established for three sectors, $\circled1$ 'chest circumference not filled up', $\circled2$ 'hip circumference not filled up' and $\circled3$ 'neither filled up for chest nor for hip circumference'. The final results of regression were presented in