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정상교합자의 치축경사도에 관한 45。측모두부방사선 계측학적 연구
김경호,박영철 대한치과교정학회 1988 대한치과교정학회지 Vol.18 No.1
The development of good arch form, the orientation of the dentition with relation to the craniofacial skeleton and the establishment of correct relationship of axial inclination of upper and lower teeth are required in normal occlusion, but different teeth present different degrees of axial inclination. The purpose of this study was to investigate the axial inclination of upper and lower teeth by analyzing 45。 oblique and 90。 cephalometric roentgenograms of 35 Korean males and 34 females with normal occlusion. The obtained results were as follows: 1. Mean and standard deviation of mesiodistal axial inclination of upper and lower teeth related to palatal plane and occlusal plane were obtained. 2. Mesiodistal axial inclination of upper first premolar was nearly perpendicular to palatal plane, and the axis of lower first premolar was nearly perpendicular to occlusal plane. 3. There was no difference in the mesiodistal axial inclination of anteriorly positioned teeth between the three groups: third molar eruption into good alignment (Group 1), third molar impaction or partial eruption (Group 2), third molar agenesis(Group 3). 4. There were low correlationships only between the axial inclination of central incisor and the mesiodistal axial inclination of canine and first premolar, but no correlationships between central incisor and posterior teeth behind first premolar.
교정용 loop 스프링의 force system에 영향을 주는 요소
최광철,김경호,박영철 대한치과교정학회 1999 대한치과교정학회지 Vol.29 No.5
생역학적으로 우수한 스프링을 설계하기 위해서 스프링의 형태에 여러 가지 변화를 주면서 각 상황에서 force system이 변하는 양상을 수치분석계산과 spring tester를 이용한 실험과 비교하였다. 주어진 해부학적인 한계내에서 최대한 생역학적 효율을 높이는 요소들을 제시하였다. 1. 스프링의 높이가 증가하면 M/F ratio는 증가하고 L/D rate은 감소한다. 2 스프링의 최소 굽힘 모멘트 부위보다 위에 wire를 첨가하면 M/F ratio는 증가하고 L/D rate는 감소한다. 3. 스프링의 최소 굽힘 모멘트 부위보다 아래에 wire를 첨가하면 M/F ratio는 감소하고 L/D rate도 감소한다. 4. 스프링의 위쪽에 아무리 wire를 많이 첨가하여도 스프링의 높이 이상의 M/F ratio는 얻을 수 없다. 5. 제한된 높이의 스프링으로 충분한 M/F ratio를 얻기 위해서는 부가적인 모멘트가 필요하다. 6. 스프링의 수평 길이가 증가할수록 M/F ratio와 L/D rate는 감소하므로 부가적인 모멘트는 점점 각도가 증 가할 수 있도록 스프링 전체에 부여할 필요가 있다. 7. L/D rate는 재료, 단면, 그리고 형태에 영향을 받지만 M/F ratio는 재료나 단면에 관계없이 스프링의 형태에만 영향을 받는다. The shape of orthodontic retraction spring was varied and force system of each case was obtained using numerical analysis and verified with spring tester. The factors for obtaining biomechanically efficient spring under anatomic limitation were suggested as follows. 1. M/F ratio increases and L/D rate decreases as loop height increases. 2. M/F ratio increases and L/D rate decreases as incorporation more wire above minimum bending moment area. 3. M/F ratio decreases and L/D rate decrease as incorporating more wire below minimum bending moment area. 4. M/F ratio can not be greater than spring height no matter how much wire is incorporate at the apex of the loop. 5. Additional moment is necessary to obtain enough M/F ratio for translation under anatomical limitation. 6. additional moment should be incorporated at every part of the spring because M/F ratio and L/D rate decreases as horizontal spring length increases. 7. Material, cross section, and shape of the spring influence L/D rate, whereas M/F ratio is influenced by the shape of the spring independent from material and cross section.
朴英哲 啓明大學校 産業經營硏究所 1985 經營經濟 Vol.18 No.1
Large cities in Korea devoted themselves in many respects to the elevation of the production efficiency and the development of medium and small size cities thanks to agglomeration economies. The concentration of the population in large cities, however, resulted in an excessive inter-regional imblance, conjestion, and environmental contamination. We are almost incapable of figuring out an optimal size of cities, but we must try to measure it econometrically. There seems to be a lot of courterplans againt the concentration of population in the capital district but is only one precedent condition-local self government. Inquiring into the trend of urbanization in Korea from 1960 until 1980, the order of the size of large cities has not changed greatly and the growth of the coastal industrial cities such as Ulsan, Masan and Pohang is remarkably perceibable. The growth rate of Seoul stands on the second position and this brings us to awareness of the danger of the concentration of population. The numerical value of statistics made by an institute was not equal to that drawn up by another. Data must be deliberately collected and arranged.