• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.158-168
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• 2016

This article is to review various methods used to investigate internal and marginal adaptation of fixed dental prostheses, and to summarize a merit, worth, and limitation of each method, using some results of previous studies. The methods of measuring internal and marginal gap are divided into two categories in this study; in vivo and in vitro. In vivo methods are clinical evaluations, including exploration, radiography, and impression technique. In vitro methods are laboratory evaluations such as direct view, cross-sectioning, and silicone replica technique using microscope. Measuring by micro computed tomography (CT) or profilometer is also in vitro methods. In recent years, the development of scanning systems is able to analyze 3-dimensional internal and marginal space in detail. As measuring and analyzing technology become more advanced, the ability to thoroughly examine crown adaptation is becoming both simpler and more efficient.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.4
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• pp.337-344
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• 2015

Purpose: The purpose of present study is to examine the correlation between the accuracy of abutment preparation and the marginal adaptation of metal coping. With this view, this study compared the correlations regard to the three different manufacturing methods of selective laser sintering technique, milling and casting. Materials and methods: Two master models were made in a different way. First model with deep chamfer margin was prepared directly by a general clinician and the second model was designed by 3-D designing software program with the same abutment preparation principle and produced by computer aided manufacturing. 12 Co-Cr alloy copings were produced respectively with three different method; SLS system, CAD/CAM milling and conventional lost wax technique from each master model. The total 72 copings fully sit on the master model were stereoscopically evaluated at 40 points along the entire circumferential margin. Results: Significant differences in the absolute marginal discrepancies of Co- Cr copings from SLS system (P=.0231) and casting method (P<.0001) were shown between hand preparation model and computer designed model. However, no significant difference was found between the two model groups from milling method (P=.9962). Conclusion: Within the limitation of this study, the effect of the accuracy of abutment preparation on the marginal adaptation of Co-Cr coping is statistically significant in SLS system and casting group. The copings produced by SLS system exhibited the lowest marginal discrepancies among all groups, and the marginal gap of this method group was influenced by the accuracy of the abutment preparation.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.2
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• pp.90-96
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• 2014

Purpose: The purpose of this study is to see what impact the heat and press-on-metal technique has on the marginal fit of metal ceramic crown. Materials and methods: Prior to the experiment, 4 metal master models were prepared. Each model has margin of chamfer, margin of heavy chamfer, margin of shoulder with bevel and margin of shoulder (collarless). Additionally, 10 crowns were made for each margin, total of 40 crowns. Marginal discrepancy between the master model and crown was observed at ${\times}100$ microscopic magnification in two states; in coping state and upon completion of making metal ceramic crown. Data analysis was performed using paired t-test along with one-way ANOVA and Duncan multiple comparison test. Results: After analyzing mean and standard deviation of marginal discrepancy, it was confirmed that marginal discrepancies were within the clinical permitted range for all states; in coping state and upon completion of making metal ceramic crown. For the chamfer group, a significant increase in marginal discrepancy upon completion of making metal ceramic crown was observed compared to the heavy chamfer group. Also, a marginal discrepancy of porcelain margin in shoulder group was significantly less than the marginal discrepancy of metal margin in chamfer and shoulder group. Conclusion: From the test result, one can conclude that marginal fit of metal ceramic crown built with heat and press-on-metal technique is not significantly different from marginal fit of metal ceramic crown built with traditional technique. And along with efficiency of this system, heat and press-on-metal technique is considered in clinic.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2010.04a
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• pp.171-175
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• 2010

• 대한치과보철학회:학술대회논문집
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• 2001.11a
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• pp.42-42
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• 2001

• 전기의세계
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• v.34 no.6
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• pp.366-371
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• 1985

Si-SiO$_{2}$계 및 다중막계의 개황과 문제점을 들어 개설하였으나 대부분의 경우 종해 생각하고 있던 모델들이 차츰 실증되어가는 단계에 있다. 그러나 이들 계는 원자적인 척도에서는 완전한 연적체라고 볼수 없고 여러 결함이 개재되어 있으므로 금후에도 술시적인 견지에서 이들의 결함구조와 각계면구조를 명확히 해 나갈 노력이 필요하다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.11
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• pp.886-897
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• 1990

This paper is proposed new optimal PWM scheme is based on a defined linear relationship between the successive pulsewidths of the PWM pattern. The calculation of the pulsewidths in the new PWM scheme is caried out without referring to the equations of CW and MW. With this scheme the PWM pattern for microprocessor controlled inverters can be composed easily by obtaining the optimal increment in sucessive pulsiwidths of the pattern. Furthmore, the harmonic level at the output of PWM inverter are always very low because this PWM pattern is selected on the basis of minimum THD. Theis scheme is applied to 1(Hp), three phase induction motor, and compared with conventional regular PWM scheme. The results of calculations and experiments show that new optimal PWM scheme could provide an effective generalized approach for minimization of harmonics in the VSI-PWM inverter.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.5
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• pp.470-478
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• 2008

Statement of problem: Use of all-ceramic prostheses fabricated with CAD/CAM systems is increasing in the dentistry. Marginal fidelity in production of all-ceramic restoration has important clinical implications and is a key consideration issue in CAD/CAM production as well. Purpose: The objective of this study was to analyse marginal fidelities of $Procera^{(R)}$ Allceram Crown. Material and methods: On 56 patients treated with $Procera^{(R)}$ system Allceram Crown at Dankook Dental Hospital, marginal discrepancies of 101 abutments were measured by stereomicroscope at coping and final restoration stages. Paired t-test and one-way analysis of variance on marginal discrepancy data were conducted to determine the presence of significant differences between measurement and measuring point stages. Results: Marginal discrepancies of final restoration ($45.82{\pm}30.84\;{\mu}m$) were lower than alumina coping ($53.84{\pm}38.83\;{\mu}m$). Furthermore, the differences were found to be statistically significant at 95% confidence level. Anterior marginal discrepancies were lower than posterior marginal discrepancies, but they were not statistically significant. Lingual marginal discrepancies were higher than other measurement sites, and the differences were found to be statistically significant at 95% confidence level. Conclusion: Within the conditions of this study, marginal fidelities of $Procera^{(R)}$ Allceram Crown were acceptable, and after porcelain build-up, marginal fitness improved over alumina coping. More careful scanning is needed for better results.

• Korean journal of applied entomology
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• v.36 no.4
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• pp.299-310
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• 1997

A mutant, or(orange body), and the KNIH(Korea National Institute of Health) strain of the German cockroach, Blattella germanica(L.) (Orthoptera: Blattellidae), were observed continuously in semi-natural conditions through video taping and data processing by computers. Male adults were individually observed for 4-5 days in a rectangular-shaped rearing cage with four different microhabitats, allowing observations of behavior such as resting, feeding, drinking and communicating with other individuals. The frequencies of visits to and times spent within harborage were determined. Although there were relatively large variations among individuals, the average stays withing harborage ranged from 47-61% of the total observation time. The duration of within-harborage time was significantly different between maternal origins, while not distinctively different between the strains. Diel differences were observed in body strains. The time spent within harborage was longer in photophase than in scotophase. visiting frequency, which represented local activity around harborage, appeared slightly higher in the or strain than in the KNIH strain, and was significant in the or strain while it was not significant in the KNIH strain. Although there were variations among individuals, similar temporal patterns in some progenies from the same maternal origins were observed in time spent within harborage and in visiting frequency.

• Journal of Forest and Environmental Science
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• v.19 no.1
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• pp.25-38
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• 2003

This study was carried out to investigate the behavioral pattern of student. faculty. administration staff. and visitor by questionnaire about the campus forest of Kangwon National University. In the question of the necessity of the campus forest. 97% of students. 100% of faculty and 91% of adminstration staff agreed with the necessity of the campus forest and 80% of university members use the campus fores t. The most frequent site of the campus forest was the Yeon-Juk pond for students and adminstration staff and was the site behind the art building for faculty. The main reason for use of the campus forest was mostly a walk. About the questions dealt with one' s satisfaction regarding the campus forest. most members evaluated the average level. and the facilities of physical training were evaluated in the unsatisfied level. The improvements for the campus forest were suggested about conservation of the campus forest. increasing of physical training facilities and the jogging courses. and managing the mineral water and pond. The visitors using the campus forests were mostly retied people or housewives older than 50 years old. 80% of visitors visits mostly in the morning and 70% of the visitors comes to the campus forest by oneself. The main reasons for use of the campus forest were a walk and dipping the mineral water. The most frequent location was the Yeon-Juk pond for the visitors. Most visitors were strongly satisfied with using of the campus forest. In the questionnaire about improvements of the campus forest, the visitors suggested the increasing of physical training facilities. conservation of the campus forest, and establishing more walking roads and benches.