• The Journal of Advanced Prosthodontics
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• v.5 no.3
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• pp.287-295
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• 2013

PURPOSE. This study investigated the effect of laser parameters and air-abrasion on the peel strength of silicon-based soft denture liner to different denture resins. MATERIALS AND METHODS. Specimens (N=180) were prepared out of three different denture base resins (Rodex, cross-linked denture base acrylic resin; Paladent, heat-cured acrylic resin; Deflex, Polyamide resin) ($75mm{\times}25mm{\times}3mm$). A silicon-based soft denture liner (Molloplast B) was applied to the denture resins after the following conditioning methods: a) Air-abrasion ($50{\mu}m$), b) Er,Cr:YSGG laser (Waterlase MD Turbo, Biolase Technology) at 2 W-20 Hz, c) Er,Cr:YSGG laser at 2 W-30 Hz, d) Er,Cr:YSGG laser at 3 W-20 Hz, e) Er,Cr:YSGG laser at 3 W-30 Hz. Non-conditioned group acted as the control group. Peel test was performed in a universal testing machine. Failure modes were evaluated visually. Data were analyzed using two-way ANOVA and Tukey's test (${\alpha}$=.05). RESULTS. Denture liner tested showed increased peel strength after laser treatment with different parameters ($3.9{\pm}0.4-5.58{\pm}0.6$ MPa) compared to the control ($3.64{\pm}0.5-4.58{\pm}0.5$ MPa) and air-abraded groups ($3.1{\pm}0.6-4.46{\pm}0.3$ MPa), but the results were not statistically significant except for Paladent, with the pretreatment of Er,Cr:YSGG laser at 3 W-20 Hz. Polyamide resin after air-abrasion showed significantly lower peel strength than those of other groups ($3.1{\pm}0.6$ MPa). CONCLUSION. Heat-cured acrylic resin, PMMA, may benefit from Er,Cr:YSGG laser treatment at 3 W-20 Hz irradiation. Air-abrasion of polyamide resins should be avoided not to impair their peel bond strengths to silicon-based soft denture liners.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.2
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• pp.200-213
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• 2000

Lasers have given dentistry a new rapid, economic, and accurate technique for metal joining. Although laser welding has been recommended as an accurate technique, there are some limitations with this technique. For example, the two joining surfaces must have a tight-fitting contact, which may be difficult to achieve in some situations. The tensile samples used for this study were made from a custom-made pure titanium and type III gold alloy plates. 27 of 33 specimens were sectioned perpendicular to their long axis with a carborundum disk and water coolant. Six specimens remained and served as the control group. A group of 6 specimens was posed as butt joints in custom parallel positioning device with a feeler gauge at each of three gaps : 0.00, 0.25. and 0.50mm. All specimens were then machined to produce a uniform cross-sectional dimension, none of the specimens was subjected to any subsequent form of heat treatment. Scanning electron microscopy was performed on representative tested specimens at fractured surfaces in both the parent metal and the weld. Vickers hardness was measured at the center of the welds with a micropenetrometer using a force of 300gm for 15 seconds. Measurement was made at approximately $200{\mu}m\;and\;500{\mu}m$ deep from each surface. One-way analysis of variance (ANOVA) and Scheffe's test was calculated to detect differences between groups. The purpose of this study is to compare the strength and properties of the joint achieved at various butt Joint gaps by the laser welding of type III gold alloy and pure titanium tensile specimens in an argon atmosphere. The results of this study were as follows : 1. When indexing and welding pure titanium, there was no decrease in ultimate tensile strength as compared with the unsectioned alloys for indexing gaps of 0.00 to 0.50mm, although with increasing gap size may come increased distortion (p>0.05). 2. When indexing and welding type III gold alloy, there were significant differences in ultimate tensile strength among groups with weld gaps of 0.00mm, 0.25 and 0.50mm, and the control group. Group with butt contact without weld gap demonstrated a significant higher ultimate tensile strength than groups with weld gaps of 0.25 and 0.50mm (p<0.05). 3. When indexing and welding the different metal combination of type III gold alloy and pure titanium, there were significant differences in ultimate tensile strength between groups with weld gaps of 0.00, 0.25, and 0.50mm. However, the mechanical properties of the welded joint would become too brittle to be acceptable clinically (p<0.05). 4. The presence of large pores in the laser welded joint appears to be the most important factor in controlling the tensile strength of the weld in both pure titanium and type III gold alloy.

• Journal of Agricultural Extension & Community Development
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• v.8 no.1
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• pp.25-40
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• 2001

The purposes of the study were to identify satisfaction and achievement of learning by female learner's characteristics, and to suggest measures to improve quality of education in internet education programs. In order to determine the educational effectiveness associated with the characteristics of learners, this study attempted to employ two way approaches by observing the degree of achievement for learning, which represents an instructor-oriented approach, and the degree of satisfaction for education, which represents a learner-oriented approach to enhance the quality of internet education for female learners. As an approach to evaluate the educational effectiveness, the degree of achievement in learning(Tyler's classical approach), and the degree of satisfaction for education (Scriven's consumer-oriented evaluation model) were utilized. A survey form was developed by the researcher after reviewing the various tools originated from Boshier, Cross, Gagne and Choi, and distributed to a panel of judges that examined the content validity of the instrument. The sample for the study consisted of 160 female learners from three universities in Seoul and capital area, and the survey form was used to collect data for this study. The SPSS WIN program was used in analyzing the data and a series of statistical tests were conducted including frequency, percentile, t-test, ANOVA, correlation, multiple regression, and factor analysis. The statistical significance level was 0.05. The following conclusion were drawn from this study of female internet education. First, it was evident that female internet learners tend to utilize information from internet, and this can be interpreted as participants' positive attitude, and voluntary participation. Second, educational facilities and services should be improved in the future, because the level of satisfaction was low in these areas compared to curriculum and educational methodology. Third, the participating factors influenced by the level of satisfaction for education of learner characteristics were the 'formation of inter-personal relationship and willingness to change' and the 'needs for education on internet', thus appeared that both social and educational needs influenced the level of satisfaction for education. Fourth, the degree of achievement in learning was higher in the order of 1) attitude 2) function 3) knowledge, thus, attitude change was the most important in achievement of learning. Fifth, the individual background that influenced the level of achievement in learning were age and educational experience. As for the individual level of achievement for learning, the younger and more educated group were more satisfied.

• Journal of Korean Home Economics Education Association
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• v.24 no.3
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• pp.175-189
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• 2012

This paper examines the effect of star-entertainer imitation on female high school students in terms of their appearance management activities such as school uniform modification behaviors, hair style care behaviors, and make-up behaviors. For this research, data of 379 female high school students living in Jeollabuk-do was analyzed through reliability analysis, factorial analysis, cluster analysis, one-way analysis of variance, and cross-tabulation analysis. In the research, based on the type of star-entertainer imitation, the female high school students were divided into three categories: active followers, psychological followers, and passive followers. The research showed that active followers, who exhibited imitation behavior most frequently and had the highest imitation desire, were most frequently involved in school uniform modification. Inclined to imitate the school uniform styles of star-entertainers in soap operas, they modified their school uniforms. The active followers were also enthusiastic about hair care, were well aware of trendy hair styles, and demonstrated a fondness for star-entertainer hair styles. In addition, they were actively involved in make-up activities. They put on basic make-up everyday and exhibited a desire to learn about make-up styles. However, passive followers, who showed the least frequent imitation behavior and the lowest imitation desire, were not as keenly involved in school uniform modification behaviors, hair style care behaviors, or make-up behaviors. The study concludes that by providing teenagers with systematic education on desirable mass media and educating them on proper behavior, an effective educational tool for guidance on clothing habits can be derived.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.6
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• pp.1018-1025
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• 2002

This study aimed to assess the prevalence of weight control behaviors and their association with food and nutrient intake among Korean adults. Study subjects were 7,340 Koreans aged 20 years and older in the 1998 Korean Health and Nutrient Survey. Cross-sectional data were collected on weight control behavior and diet using structured questionnaire by interview. Analysis of variance following after Duncan's multiple range test was used to test the differences in food and nutrient intake among three different weight control behavior groups(weight reducing attempt, weight gaining attempt, none). Current weight control behaviors were reported by 32% of the study subjects. There were significant differences in weight control behaviors between male and female subjects; weight reducing practices were 7 times greater than weight gaining practices among female subjects while it was only 1.5 times among male subjects. Weight control behaviors were not consistently associated with food and nutrient intake among male and female subjects. Moreover, greater food and nutrient intake were observed among those who trying to reducing weight than those who did not try. Therefore, it Is necessary to educate the Korean adults that balanced food and nutrient intake with sustaind weight control effort is the ideal way to achieve healthy weight.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.601-610
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• 2007

Statement of problem: The adhesion between titanium and ceramic is less optimal than conventional metal-ceramic bonding, due to reaction layer form on cast titanium surface during porcelain firing. Purpose: This study characterized the effect of titanium-ceramic adhesion after gold and TiN coating on cast and wrought titanium substrates. Material and method: Six groups of ASTM grade II commercially pure titanium and cast titanium specimens$(13mm{\times}13mm{\times}1mm)$ were prepared(n=8). The conventional Au-Pd-In alloy served as the control. All specimens were sandblasted with $110{\mu}m\;Al_2O_3$ particles and ultrasonically cleaned for 5min in deionized water and dried in air before porcelain firing. An ultra-low-fusing dental porcelain (Vita Titankeramik) was fused on titanium surfaces. Porcelain was debonded by a biaxial flexure test at a cross head speed of 0.25mm/min. The excellent titanium-ceramic adherence was exhibited by the presence of a dentin porcelain layer on the specimen surface after the biaxial flexure test. Area fraction of adherent porcelain (AFAP) was determined by SEM/EDS. Numerical results were statistically analyzed by one-way ANOVA and Student-Newman-Keuls test at ${\alpha}=0.05$. Results: The AFAP value of cast titanium was greatest in the group 2 with TiN coating, followed by group 1 with Au coating and the group 3 with $Al_2O_3$ sandblasting. Significant statistical difference was found between the group 1, 2 and the group 3 (p<.05). The AFAP value of wrought titanium was greatest in the group 5 with TiN coating, followed by the group 4 with Au coating and the group 6 with $Al_2O_3$ sandblasting. Conclusion: No significant difference was observed among the three groups (p>.05). The AFAP values of the cast titanium and the wrought titanium were similar. However the group treated with $Al_2O_3$ sandblasting showed significantly lower value (p<.05).

• Restorative Dentistry and Endodontics
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• v.31 no.1
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• pp.66-71
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• 2006

To evaluate the ratio of gutta-percha area in the canal after canal obturation with Continuous Wave of Condensation Technique (CWCT) with varying depths of plugger penetration, forty root canals of extracted human teeth were prepared up to size 40 of 0.06 taper with $ProFile^{(R)}$. Canals of three groups were filled with CWCT with System $B^{TM}$ (Analytic Tech. , USA) and different plugger penetration depths of 3, 5, or 7 mm from the apex. Canals of one group were filled with lateral condensation technique as a control The felled teeth were cross-sectioned at 1, 2 and 3 mm levels from the apical foramen. The ratio of gutta-percha area in the canal was analyzed using $Auto^{(R)}$ Cad 2000. Data were analyzed with one-way ANOVA and Duncan's multiple range test. At all levels, higher gutta-percha area ratio was found with deeper plugger penetration depth in CWCT, and cold lateral condensation group showed higher ratio than group of plugger penetration to apical 7 mm in CWCT. At apical 1 mm and 2 mm levels, group of plugger penetration to apical 3 mm showed significantly high or gutta-percha area ratio than those of apical 7 mm and lateral condensation (p<0.05). It is concluded therefore that, under the conditions of the present study, deeper plugger penetration depth results in more favorable and efficient obturation in CWCT.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.61-68
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• 2016

Digital aerial images have been commonly used in a large scale map production owing to their excellent geometry, and high spatial and radiometric resolution in recent years. However, a quality verification process for acquired images should be preceded in order to secure the high precision and reliability of produced results. Several experimental studies to verify digital imaging systems have been vigorously researched by constructing permanent test field in abroad. On the other hand, it is urgently necessary to suggest a practical scheme for an image quality verification, because this related study and experiment are still in its early stage at home. Hence, this study aims to present an easy method to measure the spatial resolution of the image in a visual way using a portable Siemens star. The images used in the study were obtained with three different cameras, two frame array sensors of DMC, UltraCamXp and a linear array sensor of ADS80. The Siemens star target appeared in every image is extracted and then the spatial resolution of image is compared with theoretical GSD(Ground Sample Distance) by a visual method. In addition, the change of spatial resolution depending on the location of the Siemens star from image center and flight direction and cross-flight direction is also compared and analyzed. As study results, while the theoretical GSDs of images taken with each camera are about 6~9cm, the visual resolutions are 1.2~1.3 times as great as the theoretical ones.

• Korean Journal of Breeding Science
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• v.40 no.3
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• pp.332-335
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• 2008

"Hwangkeumbora" is a new japonica rice cultivar developed from a three way cross of Jinbubyeo, Odaebyeo, Fukei126 at Honam Agricultural Reaserch Institute (HARI), NICS, RDA, in 2006. This cultivar has about 110 days growth duration from transplanting to harvesting under Korean climate condition. The milled kernel of "Hwangkeumbora" is translucent with non- glutinous endosperm. Amylose content of "Hwangkeumbora" is about 19.3%. "Hwangkeumbora" has better palatability of cooked rice compared with "Odaebyeo" and shows high resistant reaction to the blast, but susceptible to major diseases and insect pests. The milled rice yield of "Hwangkeumbora" is about 5.37 MT/ha under the standard fertilizer level of the ordinary transplanting cultivation. "Hwangkeumbora" would be adaptable for ordinary transplanting in northern plain, mid-mountainous, southern mountainous of Korea.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.564-567
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• 2009

"Boseog" is a new japonica rice cultivar developed from the three way cross of Kinuhikari//HR19621AC6/Sobibyeo and registered by the rice breeding team of Department of Rice and Winter Cereal Crop, NICS, RDA in 2008. This cultivar has about 110 days of growth duration from transplanting to harvesting in northern plain, northern and southern mid-mountainous area of Korea. This cultivar is about 72 cm in culm length and tolerant to lodging. In the reaction to biotic and abiotic stresses, it shows resistance to leaf blast, but susceptibility to bacterial blight, virus diseases and insect pests. The milled rice of "Boseog" exhibits translucent, relatively clear non-glutinous endosperm and midium short grain. It has similar amylose content(18.0%), lower protein content(6.3%), and similar palatability of cooked rice compared to Odaebyeo. The milled rice yield of this variety is about 5.03 MT/ha in local adaptability test. "Boseog" would be adaptable for ordinary transplanting in northern plain, mid-mountainous and southern mountainous area of Korea.