• Title, Summary, Keyword: cant

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The influence of age on lip-line cant in adults: a cross-sectional study

  • Choi, Sung Hwan;Kim, Jung Suk;Kim, Cheol Soon;Hwang, Chung Ju
    • The korean journal of orthodontics
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    • v.46 no.2
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    • pp.81-86
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    • 2016
  • Objective: The aims of this study were to assess the direction and degree of lip-line cant in Korean adult orthodontic patients and to identify the effects of sex and age on changes in the cant severity. Methods: In this cross-sectional retrospective study, lip-line cant was measured in the frontal photographs of 585 Korean patients (92 men and 493 women) aged 18-48 years. The outcome variables (direction and degree of lip-line cant) were assessed in terms of predictor variables (sex, age, sagittal skeletal relationship, and menton deviation angle). Results: The direction of lip-line cant did not differ according to sex, age, or skeletal classification. Patients had $1.6^{\circ}$ of lip-line cant on average before orthodontic treatment. Middle-aged adults displayed a significant trend toward a lower degree of lip-line cant compared to younger adults (p < 0.01). Multiple linear regression analysis showed that the degree of lip-line cant was weakly negatively correlated with age (p < 0.001). Conclusions: While the direction of lip-line cant did not differ according to the parameters explored here, the degree of cant was correlated with age in adults, independent of menton deviation. Specifically, middle-aged adults tended to display significantly lower degrees of lip-line cant than did younger adults.

A Safety Assessment and Vibration Characteristics of Railway Vehicle Passing Curves (곡선부 통과 차량의 진동특성 및 안전성 평가)

  • Park, Kwang-Soo;Lee, Seung-Il;Lee, Hi-Sung
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.10
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    • pp.993-1001
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    • 2007
  • An analysis model has been developed to assess running safety of railway vehicle passing curves. By using ADAMS/Rail, a computer analysis has been conducted by changing various parameters according to the track conditions. Analysis results show as follows: A derailment coefficient of left wheel was increased according to increase of cant at low speed, while it was decreased as increase of cant at high speed. A unload rate of left wheel was also increased according to increase of cant at low speed, while it was decreased as increase of cant at high speed. A wear number of left wheel was increased according to increase of cant at all speed, but only at 35 m/s, it was decreased as increase of cant. A friction coefficient of left wheel was Increased according to increase of cant at all speed, but only at 35 m/s. it was decreased as increase of cant.

A Study on the Running Characteristic by Rail cant variation (레일 캔트 변화에 따른 주행특성에 관한 연구)

  • Eom, Beom-Gyu;Kim, Young-Gyu;Lee, Seung-Il;Lee, Hi-Sung
    • Proceedings of the KSR Conference
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    • pp.1142-1147
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    • 2011
  • The rail cant produces a wider bearing area between the wheel and the rail by moving the wheel-rail contact area away from the gauge towards the centre of the railhead, thus improving the wear pattern of the railhead and wheel treads. It is essential to keep the rail cant within the allowable range to ensure optimum track geometry. Neglecting the rail cant geometrical parameters in a track quality evaluation can cause safety of railway vehicle and serviceability problems. In this paper, we examined the effect of the rail cant in general geometry state of the railway track using VI-Rail and analyzed running safety when the railway vehicle passing through curves depending on change of the rail cant and running speed.

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A Study on a Mutual Relation of Cant Deficiency/Rail Wear in Metro Lines (부족캔트량과 레일마모의 상관관계 고찰)

  • 홍철기;양신추;김연태
    • Proceedings of the KSR Conference
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    • pp.481-487
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    • 2001
  • In this study, the relation between cant deficiency(C') and rail wear in Seoul Metro Line 5 with STEDEF track structure(concrete bed) is studied. As a result, it is found that cant deficiency have a direct influence on rail wear, and under the condition that other negative effects are neglected, the cant deficiency in Metro Lines is demanded to set as little as possible.

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A Study on the Cant Setting in Railway Curve Section (철도곡선구간에 있어서 캔트 설정에 관한 연구)

  • 이남수
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.11 no.1
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    • pp.1-6
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    • 1993
  • The cant has setted up wrong in a part of railway curve sections, occasionally confusion occur in curve maintenance. In this study, it is suggest effective maintenance method in railway curve section about the radius of curvature, cant successive diminution length, according to the investigation of cant value, compare and analysis with straight decrease in order theory.

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Allowable Speed of Tilting Car in the Conventional Line (기존선의 선형조건을 고려한 틸팅차량의 허용속도 평가)

  • 유영화;엄주환;엄기영
    • Journal of the Korean Society for Railway
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    • v.6 no.4
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    • pp.246-251
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    • 2003
  • A quantitative analysis on the amounts of cant and lateral displacement of gravitational center due to the introduction of high-speed tilting car was carried out, based on the current alignment of the conventional line. In addition, the maximum allowable speed in curve and the level of improvement in maximum speed of tilting car were evaluated through the comparison with the maximum speed of locomotive. It was found that the tilting car produces an equivalent amount of cant, which corresponds to 47.5 % of current actual cant. This effect could be explained by the fact that 1.34 m, which is the height of gravitational center of tilting car from the rail level, is much lower than that of locomotive and thus guarantees much higher level of safety in curve. The equivalent amount of cant due to the lateral displacement of gravitational center followed by tilting in curve was 2.4 mm. It was small but not enough to be neglected and must be included in calculating the maximum speed in curve. It could be concluded that the 15 % speed-up of the conventional line is reasonable under the current condition of alignment.

Frankfort horizontal plane is an appropriate three-dimensinal reference in the evaluation of clinical and skeletal cant

  • Oh, Suseok;Ahn, Jaemyung;Nam, Ki-Uk;Paeng, Jun-Young;Hong, Jongrak
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.39 no.2
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    • pp.71-76
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    • 2013
  • Objectives: In three-dimensional computed tomography (3D-CT), the cant is evaluated by measuring the distance between the reference plane (or line) and the tooth. The purpose of this study was to determine the horizontal skeletal reference plane that showed the greatest correlation with clinical evaluation. Materials and Methods: The subjects were 15 patients who closed their eyes during the CT image taking process. The menton points of all patients deviated by more than 3 mm. In the first evaluation, clinical cant was measured. The distance from the inner canthus to the ipsilateral canine tip and the distance from the eyelid to the ipsilateral first molar were obtained. The distance between the left and right sides was also measured. In the second evaluation, skeletal cant was measured. Six reference planes and one line were used for the evaluation of occlusal cant: 1) FH plane R: Or.R - Or.L - Po.R; 2) FH plane L: Or.R - Or.L - Po.L; 3) F. Ovale plane R: Rt.F.Ovale - Lt.F.Ovale - Or.R; 4) F. Ovale plane L: Rt.F.Ovale - Lt.F.Ovale - Or.L; 5) FZS plane R: Rt.FZS - Lt.FZS - Po.R; 6) FZS plane R: Rt.FZS - Lt.FZS - Po.L, and; 7) FZS line: Rt.FZS - Lt.FZS. Results: The clinical and skeletal cants were compared using linear regression analysis. The FH plane R, FH plane L, and FZS line showed the highest correlation (P<0.05). Conclusion: The FH plane R and FH plane L are the most appropriate horizontal reference plane in evaluation of occlusal cant on 3D-CT.

Positional symmetry of porion and external auditory meatus in facial asymmetry

  • Choi, Ji Wook;Jung, Seo Yeon;Kim, Hak-Jin;Lee, Sang-Hwy
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.37
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    • pp.33.1-33.9
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    • 2015
  • Background: The porion (Po) is used to construct the Frankfort horizontal (FH) plane for cephalometrics, and the external auditory meatus (EAM) is to transfer and mount the dental model with facebow. The classical assumption is that EAM represents Po by the parallel positioning. However, we are sometimes questioning about the possible positional disparity between Po and EAM, when the occlusal cant or facial midline is different from our clinical understandings. The purpose of this study was to evaluate the positional parallelism of Po and EAM in facial asymmetries, and also to investigate their relationship with the maxillary occlusal cant. Methods: The 67 subjects were classified into three groups. Group I had normal subjects with facial symmetry ($1.05{\pm}0.52mm$ of average chin deviation) with minimal occlusal cant (<1.5 mm). Asymmetry group II-A had no maxillary occlusal cant (average $0.60{\pm}0.36$), while asymmetry group II-B had occlusal cant (average $3.72{\pm}1.47$). The distances of bilateral Po, EAM, and mesiobuccal cusp tips of the maxillary first molars (Mx) from the horizontal orbital plane (Orb) and the coronal plane were measured on the three-dimensional computed tomographic images. Their right and left side distance discrepancies were calculated and statistically compared. Results: EAM was located 10.3 mm below and 2.3 mm anterior to Po in group I. The vertical distances from Po to EAM of both sides were significantly different in group II-B (p=0.001), while other groups were not. Interside discrepancy of the vertical distances from EAM to Mx in group II-B also showed the significant differences, as compared with those from Po to Mx and from Orb to Mx. Conclusions: The subjects with facial asymmetry and prominent maxillary occlusal cant tend to have the symmetric position of Po but asymmetric EAM. Some caution or other measures will be helpful for them to be used during the clinical procedures.

A STUDY ON THE VERTICAL DYSPLASIA IN THE SKELETAL CLASS III MALOCCLUSION (골격형(骨格型) III급(級) 부정교합자(不正咬合者)의 수직부조화(垂直不調和)에 관(關)한 연구(硏究))

  • Shin, Mun-Chang
    • The korean journal of orthodontics
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    • v.20 no.2
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    • pp.333-354
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    • 1990
  • This study was designed to analyse vertical dysplasia such as open bite or deep bite in persons with skeletal Class III malocclusion. The subjects consisted of 60 control patients, 40 Class III open bite patients and 40 Class III deep bite patients. The mean age was 19.8 years in the control group, 17.8 years in the Class III open bite group and 16.5 years in the Class III deep bite group. The results were as follows: 1. In Class III malocclusion patients, the characteristics of the vertical dysplasia are under the palatal plane. 2. In Class III malocclusion patients, the items showing the characteristics of the vertical dysplasia are mandibular plane angle, lower gonial angle, lower facial height, dental height & inclination of the upper first molar, interincisal angle, maxillary & mandibular occlusal plane angle. 3. In Class III malocclusion patients, LPFH/LAFH ratio shows the highest significance among the facial height ratios. 4. In Class III malocclusion patients, open bite group has a upward cant of maxillary occlusal plane & downward cant of mandibular occlusal plane. And deep bite group has a downward cant of maxillary occlusal plane & upward cant of mandibular occlusal plane. 5. In Class III malocclusion patients, the molar teeth of the open bite group are measially inclined and those of the deep bite group are upright.

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