• The korean journal of orthodontics
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• v.51 no.6
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• pp.375-386
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• 2021

Objective: To evaluate the accuracy of a one-piece bracket jig system fabricated using computer-aided design and manufacturing (CAD/CAM) by employing three-dimensional (3D) digital superimposition. Methods: This in vitro study included 226 anterior teeth selected from 20 patients undergoing orthodontic treatment. Bracket position errors from each of the 40 arches were analyzed quantitatively via 3D digital superimposition (best-fit algorithm) of the virtual bracket and actual bracket after indirect bonding, after accounting for possible variables that may affect accuracy, such as crowding and presence of the resin base. Results: The device could transfer the bracket accurately to the desired position of the patient's dentition within a clinically acceptable range of ± 0.05 mm and 2.0° for linear and angular measurements, respectively. The average linear measurements ranged from 0.029 to 0.101 mm. Among the angular measurements, rotation values showed the least deviation and ranged from 0.396° to 0.623°. Directional bias was pronounced in the vertical direction, and many brackets were bonded toward the occlusal surface. However, no statistical difference was found for the three angular measurement values (torque, angulation, and rotation) in any of the groups classified according to crowding. When the teeth were moderately crowded, the mesio-distal, bucco-lingual, and rotation measurement values were affected by the presence of the resin base. Conclusions: The characteristics of the CAD/CAM one-piece jig system were demonstrated according to the influencing factors, and the transfer accuracy was verified to be within a clinically acceptable level for the indirect bracket bonding of anterior teeth.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.510-521
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• 2006

This investigation was undertaken to examine the extent to which tooth size and arch dimension each contribute to dental crowding. The sample included 50 subjects with well aligned dentition (25 males, 25 females) and those of 40 subjects with gross dental crowding(20 males, 20 females). Plaster model and digital model made from alginate impression taken at the one visit. Tooth size, arch length, arch perimeter, intercanine width and intermolar width was measured on the plaster and digital models. The findings in this study lead to the following conclusions. 1. In maxilla, the mesiodistal diameters of lateral incisor and premolars of the crowded group were significantly larger than those of the normal occlusion group (P<0.05). 2. In mandible, the mesiodistal diameters of central incisor, canine and premolars of crowded group were significantly larger than those of the normal occlusion group (P<0.05). 3. In maxilla, arch perimeter and intermolar width of crowded group were significantly smaller than normal occlusion group but intercanine width of crowded group were larger than normal occlusion group (P<0.05). There was no significantly difference in arch length (P>0.05). 4. In mandible, arch perimeter of crowded group was smaller than normal occlusion group(P<0.05). There were no difference in arch length intermolar width and intercanine width (P>0.05) 5. In the analysis of correlation coefficients of arch length discrepancy with variables, arch perimeter, intermolar width and mesiodistal width of 2nd premolar showed positive correlations in maxilla. 6. There was a significant difference between tooth width measurements made by the 2 methods, with all the digital model measurement larger than plaster model measurements (P<0.05) : the magnitude of the differences does not appear to be clinically relevant. 7. In the analysis for reproducibility, the plaster model measurement was showed lower degree of correlation between 1st and 2nd measurement than digital model.

• Journal of the korean academy of Pediatric Dentistry
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• v.7 no.1
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• pp.53-61
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• 1980

The purpose of this study was to statistically evaluate the spacing of primary dentition according to whether or not a space existed and measurement of amount of space in 205 children (male 114, female 91) from 2 to 6 years of age. The results were as follows; 1. In the incidence of interdental space on each region, spacing between the primary lateral incisors and primary canine in maxilla and between the primary canine and 1st primary molar in mandible showed the highest percentage, on the other hand, spacing between the 1st and 2nd primary molars in both jaw showed the lowest percentage. 2. In the kinds of interdental space, the state of primate space and other space together showed the highest percentage, and in the degree of spacing, $S_2$ showed the highest percentage in both jaw. 3. In the incidence of primate space, maxillary primate space showed higher percentage than mandibular primate space in bilateral case. 4. In the type of arch form, spaced arch showed higher percentage than closed arch and about the half of closed arch showed crowding. 5. In both Jaw, available space showed incisor segments, canine segments, and premolar segments in order of amount, and there were not statistically significant differences of sex or jaws in the amount of available space.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.2
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• pp.193-198
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• 2022

Recently, place that you need to check wearing mask and body temperature to prevent the proliferation of COVID-19 increased. But these things often measured by man manually or by machine one by one, result may be different by measuring ways, so it wastes workforce. Also, the machine generally just measures the highest temperature of the face, criteria for fever can't be trusted too. A bottleneck may occur due to crowding of people at the entrance, and because most of the measurement sites are at one entrance, it is inconvenient to track the movement of COVID-19 Confirmed cases. Thus, in this study, we intend to propose a method for suppressing the spread of infection by automatically classifying and displaying in real time using camera, thermal camera, Haar Cascade, and result selection algorithm.

• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.359-372
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• 1997

This study was conducted to discern differences of craniofacial, dentoalveolar structure and model measurements between sex and between class n openbite group and non-openbite group. The sample consisted of 49 adult patients with class Il malocclusion. 24 linear measurements, 22 angular measurements and 12 ratios were selected in lateral cephalometry. Also, arch width, length, anterior crowding, average molar relation were measured or calculated in diagnostic model. The data were evaluated by t-test and multiple discriminant analysis. The results were as follows, 1. Most linear measurements, with the exception of MnBL and AUDH, were significantly larger in male(p<0.05). but, intermaxillary relations and spatial position of maxilla and mandible relative to cranial base were not different for both sex. 2. With the exception of upper and lower anterior crowding, lower arch width, upper arch length, AMR, male exhibited significantly larger measurements in model analysis (p<0.05). 3. Size differences of maxilla and mandible between openbite and non-openbite group were not significant(p>0.05). but openbite group showed significantly increased genial angle(p<0.05), FH-CoGo(p<0.01), FH-NA(p<0.01) and FH-NB, FH-NPog (p<0.05). 4. ALFH and PUDH were larger(p<0.05) in openbite group. this result served as compensation for the spatial position of mandible relative to cranial base. AUPUDH (p<0.001) and ALPLDH(p<0.05) were lower in openbite group. upper anterior crowding was the only measurement which showed difference between openbite and non-openbite group(p<0.05). 5. For the purpose of classifying adult class n openbite and non-openbite group, multiple discriminant analysis was done genial angle, ALPLDH, AUPUDH, FH-NA were included in multiple discriminant equation. 39 cases($92.86\%$) were correctly classified when applied to the sample used in this study.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.11-16
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• 2016

Silicon carbide (SiC) has received significant attention over the past decade because of its high-voltage, high-frequency and high-thermal reliability in devices compared to silicon. Especially, a SiC Schottky barrier diode (SBD) is most often used in low-voltage switching and low on-resistance power applications. However, electric field crowding at the contact edge of SBDs induces early breakdown and limits their performance. To overcome this problem, several edge termination techniques have been proposed. This paper proposes an improvement in the breakdown voltage using a double-field-plate structure in SiC SBDs, and we design, simulate, fabricate, and characterize the proposed structure. The measurement results of the proposed structure, demonstrate that the breakdown voltage can be improved by 38% while maintaining its forward characteristics without any change in the size of the anode contact junction region.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.141-147
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• 2005

Usually, processing whole project or a part of frame work delays due to acceleration, changing orders, management, characters of project. overtime, worker crowding, early occupation in the field of construction. Through a whole project, these factors cause decreasing construction labor-productivity which is the most dependent in business of construction. These kind of decreasing of construction labor-productivity cause many negative effects, just as extension of time, increasing cost in project of construction. Regardless of characters of construction or decreasing labor-productivity, extension of time is a incident which needs acceleration, also it cause a high possibility of claim and dispute. The productivity has just a broad meaning in business of construction. That's why it's difficult to apply in the field of construction. Especially, factors increasing or decreasing labor-productivity is defined by analysis of working as qualitative and outlined evaluation. However, study of the each factor decreasing construction labor-productivity analysis has not researched, because of difficulty of systematic measurement and management. The existed studies about management of productivity are just focused on estimation of productivity, not on evaluation of productivity. It was true that I couldn't examine clearly about the analysis of how much important per each the factor which have influence on labor-productivity because of the characteristic as qualitative that the labor productivity have On this study, i tried to get the factors decreasing of labor- productivity with gathering opinions of panels of expert's studies about the factors decreasing of labor-productivity on project of construction through Delphi method and i evaluated the result factors as quantitatively and subjectively about importance of factors decreasing construction labor-productivity Analysis, using AHP Method by Saaty. Also, using Delphi and AHP method, 1 suggest substantiated method qualitative factors are measured by quantitative criteria.

• The korean journal of orthodontics
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• v.29 no.5 s.76
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• pp.563-573
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• 1999

The purpose of this study was to evaluate the availability of computer system for the measurement of tooth size in the model analysis through the comparison of two measurements: One was to use a computer; and the other was to use vernier calipers. Twenty sets of casts were used, which showed a moderate degree of crowding and full eruption of all teeth. The mesio-distal width of 12 teeth from the left central incisor to the left first molar at each set of the casts were measured twice with vernier calipers and a computer respectively. This measurement was repeated two weeks later. First, for the reproducibility analysis, the two computer measurements were compared then the vernier calipers measurements were compared. Second, all the teeth were sepapated into the region of mesiodistal contact points and its width was measured by a micrometer to obtain standard measurements. For the accuracy analysis, these standard measurements were compared with the measurements from the dental casts using two methods. The difference between them was defined as the measurement error. To investigate the cause of measurement error, an examination was made for the presence and degree of contact point deviation on each tooth from the upper and lower occlusograms, and the mesio-distal angulation of each tooth was measured with TARG. Following results were obtained through statistical analysis. 1. In the analysis for reproducibility; the measurements with vernier calipers showed significant differences in three out of twelve teeth while the computer measurements showed significant differences in one out of twelve teeth. 2. In the analysis for accuracy; compared with the standard measurements, the measurements with vernier calipers showed significant differences in three out of twelve teeth while the computer measurements showed significant differences in two out of twelve teeth. 3. Compared with the standard measurements, the measurements with vernier calipers were apt to be larger at the upper first molar, and smaller at the lower first molar The computer measurements, however, were apt to be larger at both upper and lower first molars. 4. The measurements with vernier calipers showed the largest error at the lower first molar and the degree of error was variable according to the tooth while the difference of error was small in the computer measurements. 5. In the analysis for the correlation of the degree of measurement errors with the contact point deviation index and the mesio-distal crown angulation of each tooth, the measurements with vernier calipers did not show significant correlation while the measurements with computer showed slight Positive correlations. The results of this study indicate that a computer system may be useful for the measurement of tooth size in the model analysis.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.135-142
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• 1998

The purpose of the present study was to evaluate the effect of incisor protrusion on the mucogingival parameters including the width of attached gingiva. Thirty-seven young adults with lower anterior crowding were selected for this study. From the study model, the degrees of relative and absolute protrusions were measured for each lower incisor. Clinical non height, the width of keratinized gingiva, probing depth and the width of attached gingiva were measured with digital vernier calipers and Florida Probe System. Through comparing the difference of the above measurements between protruded and non-protruded incisors, and correlation analysis between each measurement, following results were obtained: 1. The protruded incisor showed narrow width of keratinized and attached gingiva comparing to non-protruded incisor. 2. The protruded incisor showed greater clinical crown height comparing to non-protruded side while there was no difference in the probing depth between protruded and non-protruded side. 3. The difference in the width of attached gingiva between protruded and non-protruded incisors showed higher significance in the lateral incisor than in the central incisor. 4. The degree of relative protrusion showed higher correlation with the width of attached gingiva than the degree of absolute protrusion. 5. Clinical crown height showed higher correlation with the width of attached gingiva than the degree of protrusion.

• The korean journal of orthodontics
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• v.39 no.6
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• pp.372-382
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• 2009

Objective: This study was to change of pulp blood flow among maxillary and mandibular anterior tooth with mild crowding and adjacent teeth using Ultrasound Doppler graphy. Methods: The change of pulp blood flow was measured three times using Ultrasound Doppler graphy; before the attachment of brackets, after 3 week, and after 6 week. The sample consists of 15 year old eighteen patients. Results: Before the attachment of brackets, after 3 weeks, and after 6 weeks, there were no significant differences in the change of pulp blood flow in each part (maxilla and mandible) and each tooth according to period. In addition, to compare internal dangerousness of loss of the pulp vitality, when pulp blood flow is compared in each tooth before orthodontic treatment, there were no statistically significant differences in maxillary lateral incisor and mandibular canine but it showed low values in all measurement items (p > 0.05). Conclusions: Results of this study can be not only methodological preliminary data in further study such as tooth movement type of Ultrasound Doppler graphy and particular study considered the patient age, but also reference materials for the loss of pulp vitality in orthodontic treatment.