• 대한소아치과학회지
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• 제24권4호
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• pp.788-794
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• 1997

As one of the developmental disturbance in shape of teeth, a twinning has very rare frequency in permanent teeth. Because it is possible to diagnose the twinning by use of the radiograph, it is very important to detect this anomaly early by careful examining the radiographs. The twinning produces several orthodontic problem such as crowding, protrusion, ectopic eruption of adjacent teeth. Therefore it is necessary, in proper time, the extraction and orthodontic treatment should perform.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.882-884
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• 2000

This paper deals with the effect of teeth width variation in Permanent Magnet DC motor. As teeth width varies, effective flux density is influenced, which is closely related to torque-speed characteristics, output power, and efficiency of the motor. In this study. motor design was carried out using finite element method with various teeth width. Prototype motors under constraints of same armature diameter, material and axial length were made and their performances were tested.

• Journal of Magnetics
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• 제16권3호
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• pp.281-287
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• 2011

The stationary discontinuous armatures that are used in permanent magnet linear synchronous motors (PM-LSMs) have been proposed as a driving source for transportation systems. However, the stationary discontinuous armature PM-LSM contains the outlet edges which always exist as a result of the discontinuous arrangement of the armature. For this reason, the high alteration of the outlet edge cogging force produced between the armature's core and the mover's permanent magnet when a mover passes the boundary between the armature's installation part and non-installation part has been indicated as a problem. Therefore, we have examined the outlet edge cogging force by installing the auxiliary teeth at the armature's outlet edge in order to minimize the outlet edge cogging force generated when the armature is arranged discontinuously. Moreover, we obtained the calculation by analyzing the shape of the auxiliary teeth in which the outlet edge cogging force is minimized the most.

• 대한소아치과학회지
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• 제44권1호
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• pp.11-19
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• 2017

본 연구는 유치 융합치의 특징과 영구치열에 미치는 영향을 알아보고자 하였다. 4 - 6세 어린이 중 융합치가 관찰되는 84명의 어린이를 조사하였으며, 융합치의 분포는 상악보다 하악에서, 2개의 융합치보다 1개가 발생한 경우가 높은 비율로 관찰되었으며 우식이환율은 하악보다 상악에서 높았다. 계승 영구치의 선천적 결손은 상악 유중절치와 유측절치 융합, 하악 유측절치와 유견치 융합, 하악 유중절치와 유측절치 융합 순이었으며, 과잉치 발생은 상악 유중절치와 유측절치 융합, 하악 유중절치와 유측절치 융합, 하악 유측절치와 유견치 융합 순으로 나타났다. 유치의 융합에 의한 계승 영구치의 맹출 지연은 하악에서는 나타나지 않았으나 상악의 경우 지연 발육되는 과잉치의 발생 가능성 및 이로 인한 영구 중절치의 맹출 지연 양상이 높은 빈도로 관찰되었다. 따라서 융합치로 인한 맹출 지연의 문제를 최소화하기 위해 주기적인 방사선 검사 및 조기 치료가 필요할 것으로 사료된다.

• Journal of Korean Academy of Oral Health
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• 제41권4호
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• pp.296-302
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• 2017

Objectives: The water fluoridation program has been implemented since 2008, in a region of Geoje City. This study aimed to evaluate the effectiveness of the water fluoridation program on caries prevention in the permanent dentition. Methods: Evaluation surveys were conducted on 8-, 10- and 12-year-old children in the fluoridated and non-fluoridated regions of Geoje City, in 2015. The survey included 834 children from the fluoridated regions and 703 from the non-fluoridated regions. The data obtained from the survey were analyzed using the IBM SPSS statistical package version 23.0. The effectiveness of community water fluoridation in caries prevention was estimated by the differences in the decayed, missing, filled teeth (DMFT) and decayed, missing, filled surfaces (DMFS) scores, between the program and control groups. The mean numbers of fissure-sealed teeth and surfaces were adjusted to reduce their confounding effect. Results: The mean DMFT and DMFS scores (0.69 and 0.91, respectively) of 10-year-olds from the fluoridated regions, after adjusting for the numbers of fissure-sealed teeth and surfaces, were significantly lower than those of the 10 year olds (DMFT: 0.95, DMFS: 1.32) from the non-fluoridated regions. The effectiveness of water fluoridation on caries prevention in the permanent dentition, estimated based on the differences in the mean DMFT and DMFS scores, adjusted for the number of fissure-sealed teeth and surfaces, between the program and control groups of 10-year-old children, was 27.4% and 31.1%, respectively. Conclusions: These results suggest that the effectiveness of water fluoridation on caries prevention in the permanent dentition, in Geoje City was so high that this program should be implemented in other regions in Korea as well.

• 대한소아치과학회지
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• 제24권4호
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• pp.771-775
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• 1997

Ectopic eruption is defined as abnormal eruption and results in malpositioned teeth and abnormal root resorption of adjacent teeth. Ectopic eruption, first reported by Chapman, occurs in 3% of the population and that mostly in the maxilla. Etiologic factors include narrow maxilla, large maxillary teeth, retarded calcification of the first molar, inclined eruption path of the first molar and retruded position of the maxilla. Impaction of the second molar is rare and occurs mostly in the mandible. Major causes are large teeth and insufficient arch length. Halterman has devised a method of distalizing a ectopically erupting first molar by cementing a band on the second deciduous molar with a hook soldered and a button bonded to the occlusal surface of the first permanent molar. Ectopically erupted posterior teeth should be treated early to maintain normal development of the dentition, harmony of facial growth and occlusal support, a failure to do so could result in severe malocclusion, periodontal damage and continued root resorption of the adjacent teeth. Early detection and treatment is thus vital. The author is submitting this report as he has obtained favorable results in treating a patient who came to the SNUDH Dept. of Pediatric Dentistry complaining of the first molar by using a modified Halterman appliance.

• 대한소아치과학회지
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• 제24권4호
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• pp.795-804
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• 1997

Developmental dental morphological anomalies are fusion, gemination, twinning, concrescence and etc. They may cause many problems in conservative, periodontal and esthetic aspects. Fusion is a condition where two separate tooth buds unite at some stage in their development to form a bifid crown. If tooth contact occurs early, at least before the start of calcification, the two teeth may be completely unites to form a single large tooth. If tooth contact occurs after the time when a portion of the tooth crown has completed its formation, there may be union of the roots only. In fusion the dentin is always confluent. Fusion teeth is more common in the deciduous than in the permanent dentition. Fused teeth are relatively rare, and are mostly mandibular anterior teeth. Fusion of normal and supernumerary teeth or between normal teeth may occurs. The exact etiology factor of fusion is unknown, but genetic and environmental factors seems to be related. A variety of complications and subsequent treatments have been suggested on this teeth. Periodontal conditions may arise due to a groove formed at the line of fusion of the two teeth. Crowding or Protrusion with potential for malocclusion or delayed eruption of adjacent teeth. Fusion teeth appear in the anterior region, they usually cause esthetic problems. Treatments vary depending on the problem, the location, and the extent of fusion. Treatment of fused teeth has been reported from endodontic, orthodontic, periodontic, surgical and multidisciplinary. This report presents the esthetic improvements by separation of two clinical crowns. Bone reduction or endodontic treatments are not required.

• 한국치위생학회지
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• 제18권6호
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• pp.921-932
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• 2018

Objectives: The aim of this study was to investigate the number of existing permanent teeth and the denture usage status in elderly adults aged 65 years and above living in metropolitan cities and to confirm the degree of oral health inequality caused by the differences in oral conditions in each metropolitan city using the Lorenz curve and the Gini coefficient. Methods: The raw data for the analysis were obtained from the dataset of the sixth Korea National Health and Nutrition Examination Survey conducted between 2013 and 2015. The subjects included 1,764 people who underwent oral examination and answered questions. The complex samples general linear model was used to analyze the number of existing permanent teeth adjusted for age and monthly household income. The proportion of edentulousness and the denture status was analyzed using complex samples crosstabs. Results: The number of existing permanent teeth in the elderly adults aged 65 years and above was lowest in Ulsan (15.41) and highest in Gwangju (20.44). The proportion of edentulousness was highest in Busan (14.5%) and lowest in Daejeon (4.0%). With regard to the proportion of denture users, Busan had the highest tendency for denture usage (50.4%) and Gwangju had the lowest tendency (34.9) (p=0.172). The Gini's coefficient for the number of existing teeth was lowest in Busan (0.332). Oral health inequality was most severe in metropolitan cities. Conclusions: We found that oral health inequality exists among elderly adults living in the metropolitan cities of Korea using the Lorenz curve and Gini's coefficient.

• 대한소아치과학회지
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• 제34권3호
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• pp.447-453
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• 2007

본 연구는 유치열에서 치아기형 발생빈도와 영구치열에 미치는 영향을 조사하여 치아기형의 조기진단의 필요성을 평가하기 위한 것이다. 2000년도에서 2005년까지 전남대학교병원에 내원한 환자 중 파노라마 방사선 사진을 촬영한 2세에서 7세 사이의 어린이를 조사하여 유치열에서 이중치와 선천적 결손치의 유병율을 조사하고 그러한 유치열의 이상과 영구치열과의 상호관계를 조사하였다. 134명의 남아와 120명의 여아로 총 254명의 파노라마 필름을 조사하였으며 이중 8명(5명의 남아, 3명의 여아)에서 유치열에서의 결손치가 발견되었고 4명(2명의 남아, 2명의 여아)에서 유치열에서의 이중치가 발견되었다. 유치열에서 이중치의 유병율은 1.6%였으며 선천적 결손치의 유병율은 3.1%였다. 피검자 중1명은 하악의 이중치와 상악의 결손치를 가지고 있었다. 유치열의 이상이 나타난 11명 중 7명에서 계승 영구치의 결손이 발견되었다. 본 연구에서 유치열의 치아기형이 나타난 경우 계승 영구치에서 치아결손이 빈발할 수 있다는 것을 보여주었다.

• 대한치과기공학회지
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• 제15권1호
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• pp.89-94
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• 1993

The tooth size and shape of the permanent incisor teeth have been studied and analyzed about the mean size, S.D, S.E, etcs and percentage from stone model of 100 Korean male and 74 Korean female. The results were as follows. 1. The crown length of permanent incisor teeth were longer in males than in females statistical differences of males and female were not found. 2. the mesio-distal diameters of permanent incisor teeth were larger in males than in females and statistical differences of males and females were found in mandibular lateral incisor and the bigest were max. central incisor, 2nd max. lateral incisor, 3rd man. lateral incisor and the smallest were man. central incisor. 3. The square form in max. central incisor was the greatest percentage and the tapering form in max. lateral incisor and man, incisor was the greatest percentage but tapering form and ovoid form and other shape were found in max. lateral at the same ratio. 4. Concerning the labial developmental groove "midium" was the greatest percentage in the max. central incisor and "low" was the greatest percentage in the man incisor. Concerning the incisal line, straight line was the greatest percentage in the max, incisor and man, incisor and concerning the lingual tubercle "none" was the greatest percentage in the max. incisor. 5. In comparison between left side and right side of incisor, the ratio of same shape ware 22.4%-36.2% but similar or dissimilar cases were more frequently found.