• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.607-618
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• 1993

If the centric prematurity occurs after orthodontic treatment, it creates centric slide regarded as a possible factor in the cause of temporomandibular disorder and/or postorthodontic relapse. The purpose of this study was to investigate the manner of centric prematurity and centric slide in postorthodantic patients. The 36 orthodontic patients who had been treated with edgewise appliance at least 3 mouths previously were used in this study. After recording centric relation by the leaf gauge technique, the centric prematurity and centric slide were studied using SAM2 articulator and mandibular position indicator. The results were as follows : 1. The highest percentage of centric prematurities were found on the second molars. 2. The buccal incline of the palatal cusp was the most frequent area of centric prematurities in the maxilla, while the lingual incline of the buccal cusp was the most frequent area in the mandible. 3. There were no trends in the direction of centric slide on the mandibular position indicator. 4. There were no significant differences in centric discrepancies between the premolar extraction and nonextraction group.

• Journal of Oral Medicine and Pain
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• v.14 no.1
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• pp.9-17
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• 1989

The author has measured the duration of occlusal sounds during centric occlusal tapping in 30 patients with TMD and 30 normal subjects as controls, and then correlated the duration of occlusal sounds with CMI, amount of centric slide, midline deviation, habitual side of mastication, and presence of occlusal interference. The results were as follows 1. The duration of occlusal sounds during centric occlusal tapping were 36.26 msec in TMD patients and 22.8 msec in normal subjects (p<0.01). 2. The correlation between duration of occlusal sounds and CMI was significant (p<0.01). 3. The correlations between duration of occlusal sounds with amount of centric slide, midline deviation, habitual side of mastication, and presence of occlusal interference were not significant (p<0.05).

• Journal of Oral Medicine and Pain
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• v.11 no.1
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• pp.57-66
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• 1986

A study of occlusal relationship and TMJ dysfunction, parafunctional relationship and TMJ dysfunction using PRI was investigated in 23 dental students without history of being treated, ranging from 19 to 24 years old. The author used Denar Pantronic and D5-A articulator to study above. The obtained results were as follows : 1. Distribution of PRI in experimental subjects was as follows. None 13%, Slight 43%, Moderate 40%, Severe 4% Prevalance of TMJ Dysfunction was 87% 2. PRI scores of occlusal group Aoi (less than 5 in Helkimo occlusion/articulation index) was $11.72\pm2.32$ , those of occlusal group Boi (more than 5 in Helkimo occlusion/articulation index) 23.0 $\pm$ 8.06. There was a significant difference between group Aoi and group Boi(P<0.01) 3. PRI scores of occlusal group Ald (no eccentric interference, less than 0.5mm in lateral shift of slide in centric) was 12.0 $\pm$ 2.49, those of occlusal group Bld(no eccentric interference, less than 0.5mm in lateral shift of slide in centric) 24.5$\pm$5.33 There was a significant difference between group Ald and group Bld(P<0.05) 4. Prevalance of parafunction subjects(%) was 65.2%. 5. PRI scores of parafunction group was 21.6 $\pm$ 9.48, those of nonparafunctional group 18.7 $\pm$ 9.06. There was not significant difference between parafunctional group and nonparafunctional group(P>0.1)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.209-219
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• 2011

Most of the computer-based distance learning systems are asynchronous ones that allow students to download from the server the lecture previously given by a lecturer. While these asynchronous systems has the advantage that enable students to view the lecture with no time restriction, the study may not be effective due to the lack of support for real-time interaction between students and lecturers. Based on the student-lecturer-collaboration session model, this paper presents a collaboration session-centric synchronous distance learning system that supports real-time interaction between students and teachers, awareness information during lecture, and feedback from students. Basic feature of the proposed system include audio and video conferencing, text-based chat, and shared slide with annotation support.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.3
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• pp.273-282
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• 2015

Centric occlusion-maximum intercuspation (CO-MI) discrepancy is one of main causes of evoking premature contact and resultant mandibular shift. These non-physiological conditions can induce temporomandibular disease, periodontitis, and non-carious cervical lesion. Therefore, if CO-MI discrepancy exists in patients who need extensive prosthetic rehabilitation, it must be corrected and then physiological occlusion must be restored. This report describes the treatment procedure of removing CO-MI discrepancy and prosthetic rehabilitation in a patient with 3.5 mm discrepancy, multiple caries and periodontitis. Proper mandibular position and modified opening & closing movement were confirmed by ARCUSdigma II and transcranial radiograph.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.249-260
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• 1998

To understand the attachment of micro algae and their subsequent growths on artificial surfaces immersed in seawater, the relationship between attachment of diatoms on the immersed artificial substrates and species pool in the surrounding water was investigated. We used acryl slides for the study of diatom attachment and examined the surrounding water samples collected in Incheon Harbour from July 1995 to February 1997. Variations of species composition and abundances by exposure time in seawater were investigated during the early phase of biofilm formation on various substrates, e.g. glass, acryl, titanium, copper and antifouling paint-treated slides. Immigration rates of diatoms to acryl slides during spring and winter were significantly correlated with the abundance of benthic diatoms in surrounding water ($r^2$=0.78, p<0.01, n=42), suggesting that immigration rates were affected by variations of benthic diatom abundances in surrounding water. Immigration coefficient of monoraphid diatoms was 5 times higher than that of biraphid diatoms, but relative abundance of monoraphid diatoms was 3 times lower than that of biraphid diatoms on acryl slides in spring. In winter, immigration coefficient and relative abundance of centric diatoms were higher compared to other raphe forms. These results suggest that the attachment of diatoms seems to be caused by the abundance and immigration coefficients of benthic diatoms in surrounding water. Pennate diatoms predominantly attached to all artificial surfaces throughout all experimental periods. Interestingly, centric diatoms predominantly attached to all artificial surfaces in winter. Hantzschia virgata, Licmophora abbreviata and Melosira nummuloides appeared dominantly on antifouling paint-treated slides, probably being tolerant of the antifouling paint. During incubations, the abundance of attached diatoms increased exponentially on glass, titanium and acryl slides with exposure time. The maximum abundance was highest on glass slide, followed by acryl, titanium, copper and antifouling paint-treated slides. The growth rates of attached diatom community on all artificial surfaces were higher at temperature of $24-25^{\circ}C$ than that of $2-3^{\circ}C$. The growth rate of attached diatoms on glass slide was generally higher compared to other slides during the study period. Dominant morphotypes of observed species with exposure time in seawater were prostrate form Amphora coffeaeformis, fan shape Synedra tabulata, stalk type Licmophora paradoxa and chain type M. nummuloides. A micro-succession in the attached microalgal community was observed. The composition of dominant species seems to be the result of species-specific response to gradually limited space with development of microalgal film.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.1
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• pp.1-11
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• 2007

Statement of problems: The concept of CR has also changed continuously.?In order to find out the factors that affect the centric slide, studies were carried out to compare the forms of wisdom teeth eruption, lateral movement, premature contact in CR, and anterior movement. Research and statistical methods were based on the report by the 1980 Korean dental association. Material and method: In our study, 403 dentists in their twenties and dentistry students who could understand CR and CO (and who did not receive occlusal, orthodontic treatment, without extreme caries and large prosthodontic care) were compared with the 25 year old results. A segment of line parallel to the upper incisor was marked on the lower incisor. When seen laterally, a line perpendicular to the occlusal plane was drawn on the foremost area of the upper incisor. This line was extended to the lower incisor and the two points (points at the lower and upper incisors) were used as reference points for the CO. After guiding the occlusion to the CR, two lines were marked by using the same method that was used for the CO. The point in which these lines meet became the reference point of CR occlusion Results and conclusions: Results of the experiment completed in 1980 show that all 307 research members had anterior-posterior and upper-lower displacement. Displacement measurements were $0.7{\pm}0.4mm$ for the anterior-posterior displacement, $0.99{\pm}0.50mm$ for the upper-lower displacement,0.18{\pm}0.31 mm for the lateral displacement, and $1.32{\pm}0.67mm$ for the total displacement. Results of the 2006 experiment show that all 409 research members had anterior-posterior and upper-lower displacement. The anterior-posterior displacement was $1.12{\pm}0.86mm$, the upper-lower displacement was $1.02{\pm}0.71mm$, the lateral displacement was $0.61{\pm}0.56mm$, and the total displacement was $1.80{\pm}0.99mm$. No specific differences were found between each group when comparing displacement according to the forms of wisdom teeth eruption. Since 1980, the percentage of unerupted teeth has increased from 35.16% (111/307 people) to 57.5% (236/409 people). Westernization of the Korean cranial form and intraoral structure has brought about these results. In our experiment, 26.7% (109/409 people) of the subjects were cuspid guided, while 7.3% (30/409 people) were mutually guided. No specific differences were found in the amount of displacement between the two groups. Only the subjects with anteriors coming in contact made up the largest percentage group (42.3%, 173/409 people) in our study. No specific differences were found between each group.