• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.395-411
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• 1993

The purpose of this study was to examine the clear concept of the designs for cavity preparations. Among the several parameters in cavity designs, profound understanding of isthmus width factor would facilitate selection of the appropriate cavity preparation for a specific clinical situation. In this study, the cavities were prepared on maxillary first premolar and filled with gold inaly. A two - dimensional model was composed of 1037 - node triangle elements. In this model, isthmus was varied in width at 1/4, 1/3 and 1/2 of intercuspal width and material properties were given for four element groups, i.e., enamel, dentin, pulp and gold. The 500N occlusal load varied in direction and it was examined using three types of load : concentrated load, divided load and distributed load. The models were also examined with empty cavities using the devided load and distributed load. These models were analyzed the displacement and strees distribution by the two - dimensional Finite Element Method. The results were as follows : 1. All experimental models which filled with gold inlay after cavity preparation were similar direction of displacement with control model under same load type. But in the models with empty cavities, as isthmus width was wider, the degree of displacement was increased at same load type. 2. Among the experimental models which were filled with gold inaly after cavity preparation, the model II showed the least stress concentration under concentrated load and divided load. But in the models with empty cavities, the model III showed the largest stress concentration and tooth fracture is expected regardless isthmus width. 3. All experimental models showed similar displacement pattern beneath restorative material under a concentrated load. In the models with empty cavities, a divided load resulted in a lingual displacement of the lingual cusp, but a distributed load resulted in a buccal displacement of the lingual cusp. In regard to the above results, the restored models were stronger than empty models in respect to the bending moment and tensile stress. The empty models are expected to fracture regardless isthmus width. The safest isthmus width was 1/3 of intercuspal distance, which showed the least stress concentration in respect to the effect of stress distribution.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.291-316
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• 1993

Restorative procedures can lead to tooth fracture due to the relatively small amount of the remaining tooth structure. It is essential to prevent fractures by having a clear concept of the designs for cavity preparations. Among the several parameters in cavity designs, profound understanding of isthmus width factor would facilitate selection of the appropriate cavity preparation for a specific clinical situation. In this study, MO amalgam cavity were prepared on maxillary first premolar and filled with amalgam. Three dimensional, model with 1365 8-node brick elements was made by serial photographic method. In this model, isthmus was varied in width at 1/4, 1/3, 1/2 and 2/3 of intercuspal width and material properties were given for three element groups, i.e., enamel, dentin and amalgam. A load of 500 N was applied vertically on amalgam and enamel. In case of enamel loading, 2 model (with and without amalgam) was compared to consider the possibility of play at the interface between tooth material and amalgam. These models were analyzed with three dimensional finite element method. The results were as follows: 1. The stress was concentrated on the facio-pulpal line angle and distal marginal ridge of the cavity. 2. With the increase of the isthmus width, the stress spread around the facio-pulpal line angle and the area of stress concentration moved toward the proximal box. 3. In case of narrow isthmus width, the initiation point of crack would be in the area of isthmus corner of the cavity, and with the increase of the isthmus width, it would move toward the proximal box and at the same time the possibility of crack increase at the distal marginal ridge. 4. The direction of crack progressed outward and downward from the facio-pulpal line angle, and with the increase of the isthmus width, it approximated vertical direction. At the marginal ridge, it occurred in vertical direction. 5. It would be favorable to make the isthmus width narrower than a third of the intercuspal width, and to cover the cusp if isthmus width were wider than half of the intercuspal width. 6. It is necessary to apply the possibility of play to the finite element analysis.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.1
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• pp.83-93
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• 2008

The topographic effect is one of the most important component in the solution of the geodetic boundary value problem (geodetic BVP). Therefore, topographic effect should be considered properly for developing the precise geoid model, especially for the area where contains many mountains like Korea. The selection of gravity reduction method in the context of the precise geoid determination depends on the magnitude of its indirect effect, the smoothness and magnitude of the reduced gravity anomalies, and their related geophysical interpretation. In this study, Korean digital elevation model with 100m resolution was constructed and topographic effect was calculated by three reduction methods as like Helmert condensation method and RTM method and Airy-isostatic reduction method. Through the analysis of computation results, we can find that RTM reduction method is the best optimal method and the results shows that gravity anomaly and indirect effect of geoidal height are $0.660{\pm}13.009mGal$, $-0.004{\pm}0.131m$ respectively and it is the most gentle slow of the three methods. Through this study, it was found that the RTM method is better suitable for calculating topographic effect precisely in context of precise geoid determination in Korea than other reduction methods.

• Microbiology and Biotechnology Letters
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• v.33 no.3
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• pp.194-199
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• 2005

In oder to select an antifungal substance-producing antagonistic bacterium against Fusarium oxysporum casuing fusarium wilt on tomato, strain BK4 was isolated from local soil of Gyeoungbuk and was identified as Bacillus thuringiensis by 16s rDNA analysis, biochemical test, and Mcirolog TM 3.0 System. The antibiotic of B. thuringiensis BK 4 was highly produced at $30^{\circ}C$ in nutrient broth (pH 9.0). The crude antibiotic was even stable at $121^{\circ}C$ and more stable at slight alkalic condition than acid condition. It was also remained $50{\%}$ activity at pH 3.0. B. thuringiensis BK4 showed the inhibition of spore germination and the biocontrol ability against F. oxysporum causing fusarium wilt of tomato in vivo test. According to these results, B. thuringiensis BK4 was enough to use with a microbial agent for biocontrol against fusarium wilt.

• Journal of Korean society of Dental Hygiene
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• v.6 no.3
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• pp.229-242
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• 2006

This study was conducted to find out basic information on better customer satisfaction and service by examining and analyzing in what routes patients mostly have selected their dental medical organizations and how they have reacted to their dissatisfaction. The subject of study included the patients who have come to dental clinics and dental hospitals to be treated in Cheonan City, Chungnam and the researcher of this study used a survey and analyzed its gathered data using an SPSS(Statistical Package for the Social Science) WIN 11.5 Program. As analysis methods, frequency and percentage were calculated to figure out the general characteristics of its subject. In addition, a ${\chi}^2$(Chi-square) test was performed to figure out the factors that patients have selected their dental medical organizations and the following results were obtained. 1. The largest number of patients selected their dental medical organizations by hearsay and more female and married patients selected them by hearsay than other patients, and there were significant differences(p<.05). 2. The dental patients put the priority on treatment techniques in their visiting hospitals and the patients who were more than 40 years old and married patients put more emphasis on treatment techniques in their visiting hospitals than other patients and there were significant differences(p<.05). 3. The said dental patients were not satisfied with the kindness of medical staffs in their visiting medical organizations; meanwhile, the patients who were aged below 30 and had an academic background of more than university degree and were unmarried were less satisfied with the kindness of medical staffs in their visiting medical organizations than other patients and there were significant differences(p<.05). 4. In terms of improvement methods or complaints, the largest number of them said that they just ignored and endured; meanwhile, the patients who were aged below 30 and had an education of more than university degree and were unmarried were more patient of improvement methods or complaints than other patients and there were significant differences(p<.05). 5. There were more patients who have introduced their visiting medical organizations to their neighboring people than the patients who have not done it; in the meantime, the patients who were aged over 40 and were married have introduced their visiting medical organizations to their neighboring people more than other patients(p<.05).

• Analytical Science and Technology
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• v.29 no.5
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• pp.219-224
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• 2016

불산 중 극미량 음이온의 고상추출과 이온크로마토그래프를 이용한 고감도 분석법이 개발되었다. 불산 중 불소이온이 고상에 의해 제거하였고 이어서 음이온 (F⁻, CH₃COO⁻, Cl⁻, Br⁻, NO₃⁻, PO₄³⁻, SO₄²⁻)들이 이온크로마토그래프를 이용하여 연속적으로 분리하였다. 고상 추출법에 영향을 주는 각 인자들 (흡착제의 선택, 시료의 부피 및 pH, 용출 용액과 용출용액의 부피)을 결정하였으며 그 결과 흡착제로서 Oasis WAX 컬럼이 가장 우수하였고 1.0 mL의 시료부피, 용출용액으로 50 mM 초산암모늄염 5 mL가 분리능에서 가장 우수하였다. 개발한 방법에 의한 음이온 (Cl⁻, Br⁻, NO₃⁻, PO₄³⁻, SO₄²⁻)들의 방법검출한계는 25 % 불산용액 (w/w) 중에 0.04~0.30 µg/L의 범위를 보였고 정밀도는 20.0와 40.0 µg/L의 농도에서 5 % 이내를 보였다. 한 제조회사에 의한 25 % 불산 중 음이온의 4.2에서 47.5 µg/L의 범위로 모두 검출되었다. 이 방법은 시험절차가 간단하고, 재현성 및 감도가 좋아서 반도체회사에서 불산 중 음이온 불순물을 정도 관리하는데 매우 유용한 방법이 될 것으로 판단된다.

• Journal of Bio-Environment Control
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• v.15 no.2
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• pp.204-210
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• 2006

The purple color in flesh of 'Jasim' potato (Solanum tuberosum L.) tubers is due to an accumulation of anthocyanin. The experiment was conducted to determine what is the key factor among cultural environments that affect the accumulation of anthocyanin in 'Jasim' potato tubers, and the effect of nitrogen fertilization levels on that. Through analysis of anthocyanin content of purple-fleshed tubers produced under the different cultural environments of three localities and two planting dates, we determined that lower temperature during 30days before harvesting resulted in higher anthocyanin accumulation of 'Jasim' potato tubers. In the experiment of different level of nitrogen fertilization, 'Jasim' potato tubers produced in highland (Daegualryeong) showed higher content of anthocyanin in the treatment of recommended level than in treatment of lower or higher level as compared with the recommended level. However, significant difference of anthocyanin content among different nitrogen fertilization levels was not observed in lowland (Gangnung). These results suggest that the selection of locality or cropping system and the optimal fertilization management are very important factors for production of higher pigmented tubers in purple-fleshed potato.

• Korean Journal of Environmental Biology
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• v.17 no.3
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• pp.321-330
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• 1999

Nematodes were isolated using silkwom trap through the investigation of 100 soil samples from various biotopes in Korea. The 30 nematode strains from soil and dead insects by the pathogenicity aganinst silkworms (Bombyx mori mori) and insect pests of Calliphora vomitoria, Pseufazetia separata, Palomena angulosa, and Melolontha incana. Mortailty of the silkworm larvae and pupae were as high as 100% by nematode infection, those of insect of pests were varied from 20 to 100%. The 30 strains of entemopathogenic nematodes were classified into five groups of Rhabditidae, Diplogatroidae, Heterorhabitidae, Steinernematidae, and Tylenchida by morphological criteria. The genetic relationships among the 30 nematode strains were analyzed by various RAPD bands with twenty primers. The 30 nematode strains were classified into six major subgroups on the basis of the genetic similarity coefficient of 0.853. The grouping by RAPD was agree with those of morphological taxa in discrimination of the higher group, however, was not completely agree in the subgroup. The family Steinernematidae belong to Rhabditida was clarified as closer to the Tylenchida, rather than the other Rhabditida of Heterorhabitidae, Rhabditidae, and Diplogatroidae in genetic distance valule. From the result of the morphological classification and RAPD of the genomic DNA showed that genetic relationship analysis furnish infurmation on phylogenetic classification and relationships of entomopathogenic nematodes. The application of genetic similarity will overcome the limitation of taxonomy and classification of morphologically simple nematode. Several primers were confirmed those utility of identification for individual nematode strains, the methods of molecular genetics secured the simplicity, rapidity and accuracy on the selection of entomopathogenic nematodes.

• Science of Emotion and Sensibility
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• v.12 no.1
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• pp.121-128
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• 2009

The article reports findings on: (1) development of emotion assessment scale in evaluating the Television(TV) picture quality; and (2) how psychological and physical factors relate to TV picture quality. A total of 152 adjectives that specifically describe emotional reactions were first selected from a Korean dictionary of adjectives, followed by ratings on their suitability for the evaluation of TV picture quality. The final selection of 19 adjective, based on the reported rating scores greater than 4.1, were used on 126 college students who were asked to perform similarity ratings on the adjectives. Based on factor analyses (i.e., principal component analysis with oblique rotation) on the similarity of scores, the following adjectives were selectively chosen for the development of the new emotion assessment scale: 'neat-messy', 'refreshing-gloomy', 'clean-dirty', 'comfortable-tense', 'smooth-rough', 'bright-dark', 'gorgeous-plain', 'diverse-monotonous', 'satisfying', 'natural', and 'sensuous'. These adjectives composed into two distinct constructs, 'cleanness or smart' factor and 'gorgeousness' factor, which demonstrated sensitivity to changes in brightness, contrast, color, and tint in the TV picture quality, except for changes in sharpness.

• Journal of Internet Computing and Services
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• v.19 no.4
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• pp.53-63
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• 2018

The traditional mass media function of conveying information and forming public opinion has rapidly changed into an environment in which information and opinions are shared through social media with the development of ICT technology, and such social media further strengthens its influence. In other words, it has been confirmed that the influence of the public opinion through the production and sharing of public opinion on political, social and economic changes is increasing, and this change is already in use on the political campaign. In addition, efforts to grasp and reflect the opinions of the public by utilizing social media are being actively carried out not only in the political area but also in the public area. The purpose of this study is to explore the possibility of using social media based public opinion in educational policy. We collected media data, analyzed the main topic and probability of occurrence of each topic, and topic trends. As a result, we were able to catch the main interest of the public(the 'Domestic Computer Education Time' accounted for 43.99%, and 'Prime Project Selection' topics was 36.81% and 'Artificial Intelligence Program' topics was 7.94%). In addition, we could get a suggestion that flexible policies should be established according to the timing of the curriculum and the subject of the policy even if the category of the policy is same.