• Journal of the East Asian Society of Dietary Life
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• v.25 no.3
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• pp.405-416
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• 2015

This study aimed to compare the dietary habits, nutritional knowledge, and health-related behaviors of students by high school type using questionnaires. The subjects were 586 male students (academic high school students (AS); 294, specialized high school students (SS); 292) in Jinju, Gyeongnam. The frequencies of eating breakfast and snacks were higher in AS than in SS (p<0.05), whereas the frequency of drinking was higher in SS than in AS (p<0.05). The main reason for skipping breakfast was 'poor appetite' in AS (45.2%) and 'lack of time' in SS (56.5%) (p<0.05). Favorite snacks included 'pizza, hamburger' (33.0%) and 'bread, noddle, ramyun' (31.0%) in AS as well as 'pizza, hamburger' (32.5%) and 'fruit, fruit juice' (26.0%) in SS. A mean of 56.2% of students ate an unbalanced diet, and the main reason was 'untasty' (47.2%). The frequency of eating out was higher in SS than in AS (p<0.05), and the main menu while eating out was 'Korean food' in AS (96.3%) and SS (90.3%). The frequency of 'meat, fish, egg, beans' was higher in AS than in SS (p<0.05). On the other hand, the frequencies of 'fruit, fruit juices' (p<0.05), 'milk, milk products' (p<0.01), 'seaweeds' (p<0.05), 'instant foods' (p<0.001) and 'soda and ion drinks' (p<0.001) were higher in SS than in AS. The mean rates of drinking and smoking in students were 84% and 29.5%, respectively. The main reason for drinking and smoking was 'to relieve stress' in AS (38.0%) and SS (30.9%) (p< 0.001). In general, the nutritional knowledge level of SS was higher than that of AS. In conclusion, there were significant differences in the frequencies of eating breakfast, food intake, drinking and reasons for eating snacks, unbalanced diet, drinking and smoking between AS and SS. Therefore, it's necessary to provide proper nutritional education for students according to high school type.

• Journal of Nutrition and Health
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• v.53 no.3
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• pp.255-270
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• 2020

Purpose: The purpose of this study was to identify the factors that influence the consumption of convenience foods among Korean adolescents. Methods: This study had a descriptive cross-sectional study. Data were obtained from the 15th (2019) Korea Youth Risk Behavior Web-based Survey, which involved a nationwide representative sample of 57,303 middle- and high-school students. Convenience-food consumption was defined by frequency of adolescents consuming convenience foods obtained from convenience stores, supermarkets, and cafeterias over the previous 7 days. The analyzed variables were related to sociodemographic, mental health, and health behavior. The Rao-Scott χ² test was applied to examine the difference in the rate of consuming convenience foods obtained from convenience stores according to each factor. Hierarchical logistic regression was conducted to examine the factors that influence convenience-food consumption among Korean adolescents. Results: It was found that 29.1% of Korean adolescents consumed convenience foods obtained from convenience store more than three times per week. The significant influencing factors were female sex; low subjective academic achievement, and subjective household economic status; high perceived stress; low subjective sleep sufficiency; experience of depression; suicidal ideation; lower physical activity; skipping breakfast; lower consumptions of fruit, milk, and vegetables; higher consumptions of soda drinks, sweet drinks, caffeine, and fast food; lower water intake; current smoking and drinking; drug use; and experience of violence. Conclusion: These findings provide a better understanding of the sociodemographic, mental-health, and health-behavior factors that influence the consumption of convenience foods among Korean adolescents. We suggest that differentiated policies, strategies, and nutrition education need to be developed and implemented, in order to address the above-mentioned factors and thereby reduce such behaviors among Korean adolescents.

• Journal of dental hygiene science
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• v.18 no.5
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• pp.296-304
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• 2018

The purpose of this study was to propose a method for the effective management of toothbrush contamination. Toothbrush microbial contamination was analyzed according to the duration of toothbrush use, frequency of toothbrush use per day, and toothbrush storage location. We also analyzed the microbial reduction effect of vinegar, antimicrobial mouth rinse, bamboo salt, and baking soda, which are sterilization materials that can be easily used every day. We collected 45 toothbrushes from university dormitories from May to June 2018. To determine the degree of microbiological contamination with general bacteria, coliform bacteria, and Staphylococcus aureus, bristle samples were cultured at $36^{\circ}C$ for 24 hours using 3M$^{TM}$ Petrifilm plates and then measured based on Petrifilm evaluation criteria. Toothbrush microorganisms were analyzed according to the duration of use, frequency of use per day, storage location, and effect of each sterilization material. General bacteria, coliforms, and S. aureus contamination increased with frequency and duration of use (p<0.05). In particular, S. aureus showed a statistically significant increase to 36.15 CFU/ml after 1 month, 504.23 CFU/ml after 2 months, and 2,386.67 CFU/ml after 3 months (p<0.05). We found that 1% vinegar was the most effective substance for reducing general bacteria, coliforms, and S. aureus. In addition, 1% antimicrobial mouth rinse solution applied for 5 minutes was the most effective in reducing S. aureus. It is crucial to recognize the importance of toothbrush care and store toothbrushes in a dry place and replace them periodically. We recommend use of vinegar and antimicrobial mouth rinse solution to disinfect toothbrushes. These should be applied as a 1% solution for at least 1 minute. Proper care of toothbrushes is important in maintaining oral health as well as overall health. Instructions on toothbrush care should be given when teaching children or adults how to brush teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.4
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• pp.405-420
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• 2003

Purpose : The purpose of this study was to compare the fracture resistance of the IPS Empress ceramic crown with 1.0mm width rounded shoulder, which is usually recommended in all ceramic crown. and 0.5mm width chamfer finish lines on the maxillary central incisor. Material and method : After 15 metal dies were made for each group, the IPS Empress all ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan) on the metal die. The cemented crowns were mounted on the positioning jig and the universal testing machine(Zwick Z020, Zwick Co. Germany)was used to measure the fracture strength with loading on the incisal edge. And also, three-dimensional finite element stress analysis was used to measure the stress distribution with the various types of the finish lines(1.0mm width rounded shoulder, 0.5mm width chamfer), the loading site(incisal edge, incisal $\frac{1}{3}$) and the type of loading(concentration loading, distribution loading). Results and conclusion : 1. In the fracture resistance experiment according to the finish line, the mean fracture strength of rounded shoulder(876N) and the mean fracture strength of chamfer(882N) did not skew any significant difference between each other(p>0.05). 2. The stress distribution of all ceramic crown in three dimensional finite element analysis showed concentration aspect at loading point and cervical area or labial surface. 3. In metal die, there were no differences in stress distribution between finish lines, but in natural teeth model, chamfer finish line showed higher stress than rounded shoulder finish line. 4. When force was loaded on the incisal edge the stress was concentrated on the incisal edge and the cervical area of labial surface. When force was loaded on the incisal $\frac{1}{3}$, the stress concentrated on the cervical area of labial surface and the cingulum area. 5. Generally, natural teeth model showed higher and various stress than the metal die.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.6
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• pp.266-273
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• 2011

Foamed glass was fabricated by using glass powder and foaming agents. For the glass powder, we used sodalime glass which's manufactured by using refused coal ore obtained as by-product from Dogye coal mine in Samcheok. And for the foaming agents, we used Calcium carbonate, Calcium phosphate and powder of shale type refused coal ore itself which has high content of carbon materials. We additionally used liquid binder for forming, and mixed together. And we formed rectangular shape and treated $800^{\circ}C$ for 20 min in an electrical furnace. The various kinds of foam glass samples were fabricated according to the kinds of foaming agents. The physical properties of samples, as specific gravity and compressive strength, were measured. Pore structure of each samples were investigated too. Foam glass with specific gravity of 0.4~0.7 and compressive strength of 30~72 kg/$cm^2$. Especially we get satisfying foam glass sample with low specific gravity of 0.47 and high compressive strength of 72 kg/$cm^2$ by the use of liquid calcium phosphate as foaming agent. It also had small and even shape of pore structure. Therefore, it is concluded that refused coal ore can be used for raw materials to manufacture secondary glass products such as a foamed glass panel for construction and industrial materials.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.935-942
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• 2002

Gallium-doped ZnO (GZO) films were deposited on soda-lime glass substrate without heating using Ne, Ar, or Kr gas. Electrical properties of GZO films deposited at various total gas pressures were investigated for the film positions corresponding to the erosion region (region B) and outside the erosion region (region A) of the target. Region B showed high resistivity, which was attributed to the decrease in carrier density and Hall mobility, compared to region A. GZO films deposited using Ne gas showed the degradation in resistivity and crystallinity, whereas, GZO films deposited using Kr gas showed the improvement in resistivity and crystallinity. This degradation in film properties could be attributed to the film damage caused by the bombardment of high-energy particles. Especially, the energies of recoiled neutral atoms ($Ne^0,\;Ar^0,\;Kr^0$) calculated by Monte Carlo simulation corresponded to experimental results.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.5
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• pp.240-246
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• 2002

$TiO_2$ films on soda-lime-silica glasses were prepared by spin coating-pyrolysis process using titanium naphthenate as a starting material. As-deposited films were pyrolyzed at $500^{\circ}C$ for 10 min in air and annealed at 500, 550 and $600^{\circ}C$ for 30 min in air. Crystallinity of the film was investigated by X-ray diffraction analysis. A field emission-scanning electron microscope and an atomic force microscope were used for characterizing the surface morphology and the surface roughness of the film. After annealing at 550 and $600^{\circ}C$, the X-ray diffraction patterns consist of only anatase peak. Films annealed at 500 and $550^{\circ}C$ exhibited flat surfaces. While with the increase in annealing temperature to $600^{\circ}C$, the $TiO_2$ film showed abnormal growth of three-dimensional needle-shaped grains. For all samples, high transmittance, above 90 % at 500 nm, was obtained at visible range. To investigate photocatalytic properties, IR absorbance associated with the C-H stretching vibrations of a thin solution-cast film of stearic acid under 365 nm (2.4 mW/$\textrm{cm}^2$) UV irradiation was estimated.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.299-305
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• 2020

The purpose of this study is to confirm the relevance between the frequency of beverage consumption and periodontal disease among Korean adults. The data used for analysis was obtained from the 6th Korea National Health and Nutrition Examination Survey (2013-2015). The subjects were 9,042 adults aged 19 to 64. In non-smoking group, people with periodontal disease had less intake of milk, carbonated beverage, and fruit juice and more intake of coffee than people without periodontal disease. In smoking group, people with periodontal disease had less intake of milk, liquid yogurt, carbonated beverage, and fruit juice and more intake of coffee than people without periodontal disease. In the results of verifying the correlation between periodontal disease and beverage intake in accordance with the matter of smoking after revising the socio demographic characteristics, in non-smoking group, the intake of coffee was correlated with periodontal disease. In smoking group, the intake of milk was correlated with periodontal disease. Since the intake frequency of some beverages is related to periodontal disease, there should be guidelines on beverage consumption during the periodontal disease prevention education.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.574-577
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• 2011

In this study, we use the $2.5cm{\times}7.5cm$ soda lime glass as the substrate. We used the ultrasonicator. Glass was dipped in the acetone, methanol and DI water respectively for 10 minutes. Ar(99.99%)gas was used as the sputtering gas. We varied the RF power between 100~175 W with 25 W steps. Base pressure was kept by turbo molecular pump at $3.0{\times}10^{-6}$ torr. Working pressure was kept by injection of Ar gas. ZnS thin films were deposited with the radio frequency magnetron sputtering technique at various temperatures and sputtering powers. It is also clearly observed that, the intensity of the (111) XRD peak increases with increasing the RF power. Electrical properties were measured by hall effect methods at room temperature. The resistivity, carrier concentration, and hall mobility of ZnS deposited on glass substrate as a function of sputtering power. It can be seen that as the sputtering power increase from 100 to 175 W, the resistivity of the films on glass decreased significantly from $8.1{\times}10^{-2}$ to $1.2{\times}10^{-3}\;{\Omega}{\cdot}cm$. This behavior could be explained by the effect of the sputtering power on the mobility and carrier concentration. When the RF power increases, the carrier concentration increases slightly while the resistivity decreases significantly. These variation originate from improved crystallinity and enhanced substitutional doping as the sputtering power increases.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.229-235
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• 1998

This paper reports the preparation and characterization of colored coatings of $SiO_2-TiO_2-M_xO_y$ (M = Co, Cr or Cu). Films of different compositions ranging from a molar content of transition metals of 5% to 20% have been prepared on soda-lime-silica slide glasses by the sol-gel process. The films have been characterized by a photospectroscopy. The color and reflectance of the films was expressed in Lab color chart and on spectra plot. 'L' as lightness and all reflectance decreased with increase of the content of transition metals. The coating of Co, Cu and Cr cotaining system showed light blue, green and lemon-yellowish color, respectively.