• Applied Chemistry for Engineering
• /
• v.7 no.2
• /
• pp.379-386
• /
• 1996

Photosensitive compound, 1-methyl-4-[2-(4-diethylacetylphenyl)ethenyl] pridinium methosulfate(SbQ-A salt), was synthesized from dimethyl sulfate, terephthalaldehyde mono-(diethylacetal) and 4-picoline. SbQ-A salts were reacted with poly(vinyl alcohol)s, (PVA) in aqueous solution with phosphoric acid as catalyst to give photosensitive PVA-SbQ with different SbQ content and molecular weight. Relative photosensitivity of PVA-SbQ was determined by gray scale(GS) method. The rotative sensitivity of PVA-SbQ increased with increasing amount of bound SbQ in the case of high molecular weight(MW=77,000-79,000g/mol) as substrate and decreased with decreasing molecular weight of PVA with about constant(1.3mol%) amount of bound SbQ. The most sensitive polymer was obtained when SbQ group content in PVA-SbQ reached about 2.63mol% in the case of high molecular weight(77,000-79,000g/mol) PVA. This sample showed 90 times greater sensitivity than dichromated PVA as reference photosensitive system. PVA-SbQ photosensitive polymer synthesized was applied to the photolithographic screening process of phosphor on the panel of cathode ray tube(CRT). Phosphor slurry was made with PVA-SbQ, phosphor, a small amount of surfactant and other additives using water as medium. The slurry was coated onto panel, dried by heater, exposed to UV light and then developed by distilled water. When a small amount of cationic surfactant such as cetyltrimethylammonium chloride was used in the slurry formulation, the sharpness of phosphor pattern was equal to or better than that of dichromated PVA photosensitive polymer system used currently.

• The Journal of Korean Academy of Prosthodontics
• /
• v.42 no.2
• /
• pp.226-237
• /
• 2004

Purpose: Four finite element models were constructed in the mandible having a single implant fixture connected to the first premolar-shaped superstructure, in order to evaluate how the shape of the fixture and the implant-abutment connection would influence the stress level of the supporting tissues fixtures, and prosthethic components. Material and methods : The superstructures were constructed using UCLA type abutment, ADA type III gold alloy was used to fabricate a crown and then connected to the fixture with an abutment screw. The models BRA, END , FRI, ITI were constructed from the mandible implanted with Branemark, Endopore, Frialit-2, I.T.I. systems respectively. In each model, 150 N of vertical load was placed on the central pit of an occlusal plane and 150 N of $40^{\circ}$ oblique load was placed on the buccal cusp. The displacement and stress distribution in the supporting tissues and the other components were analysed using a 2-dimensional finite element analysis . The maximum stress in each reference area was compared. Results : 1. Under $40^{\circ}$ oblique loading, the maximum stress was larger in the implant, superstructure and supporting tissue, compared to the stress pattern under vertical loading. 2. In the implant, prosthesis and supporting tissue, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 3. In the superstructure and implant/abutment interface, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 4. In the implant fixture, the maximum stress was smaller with the internal connection type (FRI) and the morse taper type (ITI) when compared to that of the external connection type (BRA & END). 5 The stress was more evenly distributed in the bone/implant interface through the FRI of trapezoidal step design. Especially Under $40^{\circ}$ oblique loading, The maximum stress was smallest in the bone/implant interface. 6. In the implant and superstructure and supporting tissue, the maximum stress occured at the crown loading point through the ITI. Conclusion: The stress distribution of the supporting tissue was affected by shape of a fixture and implant-abutment connection. The magnitude of maximum stress was reduced with the internal connection type (FRI) and the morse taper type (ITI) in the implant, prosthesis and supporting tissue. Trapezoidal step design of FRI showed evenly distributed the stress at the bone/implant interface.

• Journal of the Korea Convergence Society
• /
• v.9 no.8
• /
• pp.95-100
• /
• 2018

The Korea Convergence Society. The aim of this study was to evaluate the association between alcohol consumption and periodontal diseases in Korea adults. The date from the 2014 Korean National Health and Nutrition Survey were used, and 4,328 subjects over 30 years were included in the analysis. Periodontal disease was assessed using the Community Periodontal Index. The adjusted odds ratio of drinking experience, drinking frequency, the drinking amount and the drinking duration were calculated from the logistic regression model with the never-drinkers as a reference group and the logistic model controlled for age, gender, education, and diabetes. This study found that the risk of periodontal disease according to the drinking status of adults over 30 years of age was 1.39 times (95% CI=1.01-1.90) higher than that of non-drinking group when the number of drinks consumed at one time was more than seven glasses. The frequency of binge alcohol consumption, amount of alcohol consumption and duration of alcohol consumption were significantly associated with the risk of periodontal disease in a dose-response pattern among over 30 years. Alcohol consumption was discovered to be a potential risk indicator for periodontitis. Dental practitioners need to be aware that patients who drink may be at higher risk of periodontitis and could benefit from advice to quit drinking and maintain regular dental visits.

• Journal of Periodontal and Implant Science
• /
• v.23 no.1
• /
• pp.109-126
• /
• 1993

Refractory periodontitis manifest progressive attachment loss in a rapid and unrelenting manner regardless of the type or frequency of therapy applied. The purpose of this study was ta evaluate the relation between the level of cytokines in GCF and periodontopathic microflora with disease activity of refractory periodontitis. Selection of patients with refractory periodontitis (7 males, 3 females) were made by long term clinical observation including conventional clinical history and parameters. Teeth that showed pocket depth greater than 6mm were selected as sample teeth. Subjects were examined at baseline and after 3 months. Prior to baseline test, individual acrylic stent was fabricated. Reference grooves were made on each sample tooth site. Pocket depth and attachment loss were measured by Florida Probe. Gingival index was measured at 4 sites each sample teeth. Disease activity was defined as attachment loss of ${\ge}$ 2.1mm, as determined by sequential probing and tolerance method. The pattern and amount of alveolar bone resorption was observed with quantitative digital subtraction image processing radiography. Morphological analysis of subgingival bacteria was taken by phase contrast microscopy. Predominant cultivable bacterial distribution and frequency were compared between disease-active and disease-inactive site using immunofluorescence microscopy and selective microbial culturing. Levels of $interleukin-l{\beta}$, 2, 4, 6 and $TNF-{\alpha}$ in GCF and blood serum sample were quantified by ELISA. In active sites, P. intermedia was significantly increased to compare with inactive site. $IL-1{\beta}$, IL-2, IL-6 and $TNF-{\alpha}$ in GCF were increased in active sites and IL-2 in serum was increased in active patients significantly. Alveolar bone loss in active site was correlated with $IL-1{\beta}$, IL-2 in GCF. And loss of attachment in active site was correlated with IL-2 in GCF. These results demonstrate that IL-2 in serum, $IL-1{\beta}$, IL-2, IL-6 and $TNF-{\alpha}$ in GCF, P, intermedia might be used as possible predictors of disease activity in refractory periodontitis before it is clinically expressed as attachment loss and quantitative alveolar bone change.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.34 no.2
• /
• pp.104-115
• /
• 2018

Purpose: The purpose of this study is to evaluate the image acquisition ability of intraoral scanners by analyzing the comprehensiveness of scanned images from standardized model, and to identify problems of the model. Materials and Methods: Cast models and 3D-printed models were prepared according to international standards set by ISO12836 and ANSI/ADA no. 132, which were then scanned by model scanner and two different intraoral scanners (TRIOS3 and CS3500). The image acquisition performance of the scanners was classified into three grades, and the study was repeated with varying surface conditions of the models. Results: Model scanner produced the most accurate images in all models. Meanwhile, CS3500 showed good image reproducibility for angled structures and TRIOS3 showed good image reproducibility for rounded structures. As for model ingredients, improved plaster model best reproduced scan images regardless of the type of scanner used. When limited to 3D-printed model, powdered surface condition resulted in higher image quality. Conclusion: When scanning structures beyond FOV (field of view) in standardized models (following ISO12836 and ANSI/ADA 132), lack of reference points to help distinguish different faces confuses the scanning and matching process, resulting in inaccurate display of images. These results imply the need to develop a new standard model not confined to simple pattern repetition and symmetric structure.

• Korean Journal of Community Nutrition
• /
• v.1 no.2
• /
• pp.161-177
• /
• 1996

This study attempts to propose a priority of national nutrition targets and strategies for health promotion by the year 2000 in Korea, as a part of the task set for national health promotion objectives and strategies. Among all of the important health issues raised, ten were chosen, nutrition was one priority area. In the first part, the current status of the nutrition-related health problems and risk factors are reviewed, in conjunction with the newly arisen health phenomena, such as changes in prevalence of lifestyle disease and causes of death, changes of food consumption patterns in our country. In the second section this study suggests six feasible national nutrition targets, eight implementing strategies and current major tasks on the basis of the assessment of present status and in consideration of the other health promotion goals and strategies, with reference to that of other developed countries. The main targets and strategies are suggested as follows ; Firstly, the national nutrition monitoring and surveillance system should be established for identifying the nutritional problems for our people, and current National Nutrition Survey is a strong need for improvement to a more comprehensive and reliable one. Secondly, effective administrative mechanism should be operation at national level for the development of nutrition policy. Ministry of Health and Welfare (MOHW) as well as local health department must be remarkably renewed and strengthened the nutrition section. And it is recommended that MOHW organize and operate “The Council of Nutrition”, in which all government authorities related with foodstuffs and nutrition would incorporated. The Council of Nutrition would act as an adjustor as well as a coordinator in nutrition related policy-making. Thirdly, healthy eating pattern will be supported by activities of introducing a nutrition labeling for providing consumers with the necessary information and skills for food selection. Fourthly, nutrition education, and nutrition intervention programs will be carried out in various settings such as health centers, schools, and clinical fields and workplace. Fifthly, the current dietary guidelines shall be continuously improved in detail, and publicly circulated to particular levels of people by age group and by health condition. And finally, researches and epidemiological studies particularly in regard to diet for development of chronic diseases are needed for more investigation and up-to-date national health and nutrition data should be collected with the support and cooperation from the various medical professional teams . (Korean J Community Nutrition 1(2) : 161-177, 1996)

• Korean Journal of Community Nutrition
• /
• v.10 no.6
• /
• pp.952-962
• /
• 2005

To explore the relationship between economic status and food and nutrient intake patterns, the 2001 National Health and Nutrition Survey result was analyzed. Dietary intake data of 6,978 Korean adults of 20 years and older who participated in the 2001 National Health and Nutrition Survey were used along with their demographic data. Economic status of the subjects was classified into the following 4 groups based on the self-reported average monthly income of household with reference to the minimum monthly living expenses (MLE) in 2001 : low < $100\%$ MLE $\leq$ middle < $200\%$ MLE $\leq$ high < $300\%$ MLE $\leq$ higher, Individuals in the higher income class had significantly higher mean intake for most of the nutrients including energy, protein, carbohydrate, fat, calcium, thiamin, riboflavin, niacin and vitamin C, and a higher percentage of energy intake from fat. In addition, they consumed more animal foods including meats, eggs, fish/shellfish, milk/dairy products and fats. On the other hand, the mean intakes of individuals in the lower economic class for calcium, vitamin A, and riboflavin were lower than $75\%$ of RDAs. And, there was a predominant difference in contribution of fat to total energy intake among the groups of different economic status. These results showed that household income is an important factor influencing the food and nutrient intake patterns of the Korean adult population. Although individuals at different age classes may respond differently to a change in economic status, developing and implementing nutrition policy and intervention programs for those nutritionally vulnerable groups should consider the economic status as an important factor to customize and differentiate the content of the Program. (Korean J Community Nutrition 10(6) : $952\∼962$, 2005)

• Korean Journal of Remote Sensing
• /
• v.33 no.6_1
• /
• pp.1029-1040
• /
• 2017

Wildfires release a large amount of greenhouse gases (GHGs) into the atmosphere. Fire radiative power (FRP) data obtained from geostationary satellites can play an important role for tracing the GHGs. This paper describes an estimation of the Himawari-8 FRP and fire emissions for Samcheock and Gangnueng wildfire in 6 May 2017. The FRP estimated using Himawari-8 well represented the temporal variability of the fire intensity, which cannot be captured by MODIS (Moderate Resolution Imaging Spectroradiometer) because of its limited temporal resolution. Fire emissions calculated from the Himwari-8 FRP showed a very similar time-series pattern compared with the AirKorea observations, but 1 to 3 hour's time-lag existed because of the distance between the station and the wildfire location. The estimated emissions were also compared with those of a previous study which analyzed fire damages using high-resolution images. They almost coincided with 12% difference for Samcheock and 2% difference for Gangneung, demonstrating a reliability of the estimation of fire emissions using our Himawari-8 FRP without high-resolution images. This study can be a reference for estimating fire emissions using the current and forthcoming geostationary satellites in East Asia and can contribute to improving accuracy of meteorological products such as AOD (aerosol optical depth).

• Korean Journal of Remote Sensing
• /
• v.34 no.5
• /
• pp.763-775
• /
• 2018

In this study, the effects of wind fences on the dispersion of the particles emitted from a constructing site located in the building-congested area in Busan, Korea, using geographic information system (GIS) and a computational fluid dynamics (CFD) model. We averaged the wind speeds observed for 10 years at the Busan automated synoptic observing system (ASOS) and we used the averaged wind speed as the wind speed at the reference height (10 m above the ground level). The numerical simulations were performed for 16 inflow directions, before and after the construction of wind fences with the heights of 5 m and 10 m (total 48 simulations). The detailed flows were analyzed for the northeasterly and south-southwesterly cases which predominantly observed at the Busan ASOS. In the northeasterly case, high concentration appeared at the elementary school next to the construction site due to transport by the airflow coming from the northeast. In the 5-m wind fence case, the wind speeds were slightly weaker and the spread of the fugitive dust was slightly less than those in the no wind fence case. In the 10-m wind fence case, the dust concentration at the elementary school has the maximum reduction of 37%. In the south-southwesterly case, the flow pattern became complicated in the construction site due to the terrain and buildings. Fugitive dust was stagnant at the south side of the construction site but rather spread to the north, increasing the concentration at the elementary school. After the wind fence was built, the concentrations inside the construction site became high as the wind speeds decreased inside, but, the concentrations in the elementary school rather decreased.

• Journal of Korean Society of Transportation
• /
• v.17 no.2
• /
• pp.21-27
• /
• 1999

The objective of this study is to clarify the relationship between accident rate and V/C for freeway facility. The relationship can be used as a basic reference to predict and prevent traffic accident. The traffic volume and the number of accidents from 1992 to 1997 on Shingal-Ansan Freeway were analyzed in this study to clarify the relationship. Hourly accident rate and V/C were calculated for each facility sections : basic freeway section, tunnel section and toll gate section. The accident rate models consisting of an independent variable of V/C were established by repression analysis and compared with each other. The relationship between accident rates and V/C ratios represented U-shaped pattern for all sections. The result of this study indicates that accident rates are highest in the low hourly V/C range, decrease with increasing V/C ratio, and then increase as the V/C ratio increases. The accident rate of toll gate section is in general higher than that of other sections. Although the accident rate of tunnel section is higher than that of basic freeway section when V/C is above 0.67, there is no significant difference of accident rate between basic freeway and tunnel section when V/C is between 0.5 and 0.8. Basic freeway tunnel and toll gate section have the minimum accident rate when V/C is 0.78, 0.75 and 0.57 respectively.