• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.31-40
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• 2003

In this paper, optimal cutting condition to minimize the form error in side wall machining with a flat end mill is studied. Cutting forces and tool deflection are calculated considering surface shape generated by the previous cutting such as roughing. Using the form error prediction method from tool deflection, optimal cutting condition considering form accuracy is investigated. Also, the effects of tool teeth number, tool geometry and cutting conditions on form error are analyzed. The characteristics and the difference of generated surface shape in up and down milling are discussed and over-cut free condition in up milling is presented. Form error reduction method through successive up and down milling is also suggested. The effectiveness and usefulness of the presented method are verified from a series of cutting experiments under various cutting conditions. It is confirmed that form error prediction from tool deflection in side wall machining can be used in optimal cutting condition selection and real time surface error simulation for CAD/CAM systems. This study also contributes to cutting process optimization for the improvement of form accuracy especially in precision die and mold manufacturing.

• Korean journal of applied entomology
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• v.34 no.4
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• pp.308-313
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• 1995

Drosophila melanogaster, D. simulans, and D. sechellia are closely related species which belong to the D. melanogaster complex; the first two cosmopolita and the last one restricted to th Seychelles archipelago. The phenogenetical relationship between this complex and their hybrids were investigated by the comparison of sex-comb tooth number an genital arch of male. In interspecific hybrids of all crosses between three species four hybrid males were produced and completely sterile. Males of D. simulans (${O}_{9}$) have significantly less sex-comb teeth (mean 8.35) than either D. melanogaster (OR, mean 10.73) and D. sechellia (Ja, mean 10.60). From the analysis by the number of sex-comb tooth in interspecific hybrids we could not represent the direction of heredity nature. each species of D. melanogaster complex were characteristic in the shape of the genital arch, which readily allows these species to be distinguished. The common structure of the genital arch in the interspecific hybrids were mosaic-like structure between parental species.

• Journal of the korean academy of Pediatric Dentistry
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• v.41 no.3
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• pp.266-271
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• 2014

This study was performed to evaluate the relationship between the types of maxillary labial frenum attachment and the dental age in children. The maxillary labial frenum attachment levels were examined from the children who visited Chonbuk National University Dental Hospital between April, 2010 and December, 2013. The total number of the examined children was 320 (160 males, 160 females) between the age of 2 and 12. The types of maxillary labial frenum were categorized according to Placek's classification and each type was analyzed for its relationship with both Hellman's dental age and the eruption stage of permanent maxillary anterior teeth. The observed forms of maxillary labial frenum along with their frequency were as follows: gingival (56.3%), papillary (20.6%), mucosal (18.1%) and papillary penetrating (5.0%). The frenum form showed no significant difference due to gender (p > 0.05). From IC to IIIB in Hellman's dental age, the mucosal type increased significantly (p < 0.001). There was no significant relationship between the types of maxillary labial frenum attachment and the eruption state of permanent maxillary anterior teeth (p > 0.05).

• Journal of Korean society of Dental Hygiene
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• v.8 no.3
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• pp.127-138
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• 2008

Dental caries in infants is a representative oral disease causing the malocclusion of permanent dentition and developmental variations in the permanent teeth, so it is very important to manage caries in infants. Thus, in order to survey mothers who visited pediatric dentistry concerning their awareness of nursing bottle caries and to obtain data necessary for developing education materials to prevent nursing bottle caries, the present study conducted a survey using a self reporting questionnaire with 205 mothers who visited the Pediatric Dentistry of a dental hospital in Cheonan with a child aged below 5 during the period from June 7 to August 2 in 2008, and obtained results as follows. 1. The awareness of dental caries was highest in the group aged over 37 months 96.8%, and next in order of age 13~24 months 96.5%, 25~36 months 94.5%, and younger than 13 months 83.3%. 2. The awareness of nursing bottle caries was highest in infants aged over 37 months 58.7%, and next, in 13~24 months 57.9% and in 25~36 months 54.8%, and lowest in infants younger than 13 months 33.3%, suggesting the necessity of education on nursing bottle caries(p=0.423). 3. As to the time of the first visit to dental clinic, 50.0% of infants younger than 13 months, 52.6% of those aged 13~24 months, and 49.3% of those aged 25~36 months replied the completion of the eruption of primary teeth, and 36.5% of those aged over 37 months replied the occurrence of dental caries. Thus, the motives for visiting dental clinic were different among the age groups, and the differences were statistically significant(p=0.005). 4. The age of toothbrushing to be started by mother's opinion was 6 months in 0.5%, 12 months in 68.8%, 18 months in 22.9%, 24 months in 5.9%, and 25 months in 1.0%, and no statistically significant difference was observed according to age. 5. The number of toothbrushing was usually once a day after meal. and increased by in age was shown statistically significantly difference(p=0.035). 6. The most frequent method of preventing nursing bottle caries was regular toothbrushing in all the age groups, and next restriction of sugar intake, regular dental consultation, and fluoridation in order The most effective prevention of dental caries was regular visit to dental clinic and next, toothbrushing after meal.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.607-614
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• 2013

This study has been conducted to investigate the effect of self awareness of halitosis on the quality of life related to oral health in patients with chronic renal failure undergoing hemodialysis and use basic data related to oral health of patients with chronic renal failure which is very rare in Korea. In terms of oral symptoms based on awareness of halitosis, there were significant differences in symptoms of teeth pain in the past one month, bleeding gums, symptoms of tongue or cheek pain, dry mouth, In terms of status of oral functions, there were significant differences in discomfort upon chewing foods, difficulty of pronunciation and presence of lost teeth. As the results of analysis of effect of self awareness of halitosis on the quality of life related to oral health in patients with chronic renal failure, it was shown that there were significant effects in psychological discomfort(B=-2.028, p<.01), poor social skills(B=2.596, p<.01) and social disadvantage(B=-2.173, p<.01). Thus, because self awareness of halitosis gives psychologically and socially negative effects, it could be an important factor to patients with renal failure whose number is rapidly increasing.

• Journal of Korean society of Dental Hygiene
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• v.7 no.4
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• pp.405-418
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• 2007

The purpose of this study was to examine the interest level of mothers in oral health. The subjects in this study were 184 mothers whose children attended daycare centers in the city of K. A survey was conducted from March 15 through April 30, 2007, and SPSS WIN 11.5 program was employed to analyze their answer sheets. The findings of the study were as follows: 1. A group of mothers whose children brushed their teeth three times a day on the average made up 55.7 percent of those who were at the age of 35 and under. Among the mothers having three or more children, those mothers accounted for 59.1 percent. The daily mean toothbrushing frequency of children was higher among the better-educated mothers. 2. Concerning dietary and oral guidance, the mothers whose academic background was better curbed their children's excessive sugar intake more often, and the gap between them and the others was statistically significant(pE.05). As to the importance of oral health by the number of child and academic credential, those who had two children(36.0%) taught them the importance of oral health frequently(pE.01), and the better-educated mothers taught about it often(pE.05). The gap between the groups and the others was significant. 3. As for experience of visiting dental institutions, the working mothers visited dental institutions more often than the stay-at-home mothers, and the gap between them was statistically significant(pE.05). Regarding purpose of the visit, the largest group aimed to get treatment(64.6%), followed by having a dental checkup(14.6%) and receiving preventive treatment(13.5%). As to any inconveniences in using dental institutions, those who were working and who were in the upper income bracket found it more inconvenient to do that because of a long distance or time constraints. The gap between them and the others was significant. 4. In regard to concern for dental care, the mothers who were better educated(pE.001) and whose family income was 3 million won or more had their teeth scaled more often, and the gap between them and the others was statistically significant(pE.01). The rate of the regular visitors of dental institutions stood at 32.7 percent of the junior-college graduates, 31.0 percent of the mothers receiving college or higher education and 10.1 percent of the high-school graduates(pE.01). And those who earned larger income paid a visit to dental institutions more often and on a regular basis. The gap between them and the others was statistically significant(pE.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.1
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• pp.25-35
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• 2020

The purpose of this study is to evaluate the morphological characteristics of the roots and roots canals of primary molar teeth using Cone-Beam Computed Tomography (CBCT). A total of 68 CBCT images of children aged 4 - 5 years was used for this study. A total of 160 molar teeth were analyzed. Various parameters such as the number of roots and canals, length of root and root canal, and the angulation and shape of the roots were analyzed. All maxillary primary molars had 3 roots. The presence of 2 root canals in 1 root was only observed in the mesiobuccal root of maxillary primary second molars. Most mandibular primary molars had 2 roots, and most mesial roots had 2 root canals. Concerning the length of the roots, the palatal root of the maxillary primary molar was found to be longest whereas the distobuccal root was shortest. In mandibular primary molars, the mesial root was longer than the distal root. In maxillary primary molars, the palatal root had the greatest angulation whereas the distal root has the greatest in mandibular molars. The root and root canals of maxillary primary molars were more curved in shape whereas mandibular primary molars were straight.

• Journal of Technologic Dentistry
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• v.35 no.2
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• pp.145-155
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• 2013

Purpose: The recent proliferation of the aging population, oral health care is closely related to the mental health of the elderly is very important being recognized. Provide basic data for improving the quality of life for the elderly, to determine whether the oral health of the elderly whether oral self-perception of health and any related wish. Methods: Surveys to May 20 from April 15, 2011, subjects were elderly and living in Daejeon and Chungnam 277 people were examined. All the statistics using SPSS 18.0 for the determination of statistical significance, and the significance level was 0.05. Results: 1. Recognized, the most common oral health, self-aware bad the state (46.2%) there was no significant difference in the general characteristics according to self-Oral health status, remaining natural dimensions or the intra-oral prosthetic, there was no significant difference. More teeth, residual phase, in accordance with intra-oral prosthetic mandibular Not all dentures, partial dentures, full dentures net self-perception of oral health status better recognized. 2. According to the type of partial dentures, oral health status self-phase, mixed mandibular removable, fixed, fixed, removable partial dentures in order to recognize that good oral health, self-aware state, showed between them, there was no significant difference. 3. Of variable dimension that has nothing to do with the remaining natural maxillary and mandibular prosthetic maxillary prosthetic mandibular partial dentures, age income, a positive correlation was negatively correlated. The case of the mandible, the mandibular prosthetic mandibular partial denture, maxillary prosthetic, the amount of income were correlated. 4. Intra-oral Prosthetics correlation variables in the maxillary, mandibular prosthesis, the positive correlation between income, age was negatively correlated, if the income of the mandible. Maxillary partial denture has nothing to do with the variable portion of the mandibular denture, age was a negative correlation was found. Conclusion: Satisfaction and how now it is important simply to live as long, but you need to pay attention to the quality of life, sometimes with an aging population and the increase of soybean To buy the loss of teeth causes the typical health problems of the elderly. Elderly people of any relevant oral health and the oral cavity by the state to determine whether to provide the basic data for oral health education was more residual value, intra-oral prosthetics there is no more self-aware, the oral health status is good to recognize that appeared. Strengthen the oral health education to improve the quality of life of the elderly, and is thought to be necessary to increase the number of residual.

• The korean journal of orthodontics
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• v.30 no.1 s.78
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• pp.91-99
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• 2000

This study was done to identify the changes of bite force and occlusal contact between before and after stabilization splint therapy. 16 female patients, accepted for orthodontic treatment at the Department of Orthodontics, College of Dentistry, Chosun University, were selected as the sample of this investigation. For comparisons, the samples of 16 were divided into just before stabilization splint, 1 month after stabilization splint, 2 months after stabilization splint, and 3 months after stabilization splint and used the T-scan system to identify the bite force and occlusal contact changes for each group. Statistical analysis of the data was carried out ANOVA tests, and Turkey tests using $SPSS/PC^+$. The results were as follows : 1. Bite force change from just before treatment to 1 month after stabilization splint therapy was statistical significantly decreased (P<0.05). 2. Bite force changes from 1 to 3 months after stabilization splint therapy showed no statistical significance (p>0.05). 3. The changes of anterior occlusal contacts showed no statistical significance regardless of the wearing periods of stabilization splint (P>0.05). 4. The changes of posterior occlusal contacts from just before treatment to 1 month after stabilization splint therapy was statistical significantly decreased (P<0.05). 5. The changes of posterior occlusal contacts Outing 1 to 3 months after stabilization splint therapy showed no statistical significance (P>0.05). 6. Posterior teeth rather than anterior teeth were more influenced by the changes of the number of occlusal contacts. To sum up above results, we may respect to capturing and stabilizing centric relation Position just 1 month after stabilization splint therapy.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.549-554
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• 1998

The prevalence of the supernumerary tooth is $1{\sim}4%$. It usually occurs in the permanent dentition. It frequently occurs in the maxillary mid palatal area. The presence of the supernumerary tooth causes the following problems ; (1) interfering the eruption of successional tooth, (2) displacing the neighboring teeth, (3) resulting large diastema, (4) forming cystic change. So the supernumerary tooth should be removed as soon as possible. To extract the supernumerary tooth, the exact position must be noticed first. Radiographic techniques that were used in the past are tube shift technique, right angle technique, sterioradiography, using radiopaque contrast media and conventional tomography. But these methods include the subjective opinion of the operator. So, a technique eliminating the operator's opinion and showing the position 3-dimentionally can be used. 3-dimentional computed tomography equipped with dental softwares can show the position of the impacted supernumerally tooth in 3-dimentional position. It has an advantage to eliminate the subjective opinion of the operator. With a fast computer this techenique is done in a relatively short period of time. The rationale of this methods is relatively simple. After tacking X-ray and reconstructing the data 3-dimentionally, sequential removal of the soft tissue and hard tissue(bone) CT number leaves the teeth alone in 3-dimentional position. The image can be seen from anywhere, so the operator can see the image in front, rear, upper, and lower positions. In both cases 1 and 2, the position of the impacted supernumerary tooth is viewed by the 3-dimensional computed tomography. And it made the operator easy to figureout the exact position.