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최항문,이원진,허민석,이삼선,김정화,최순철,박태원 대한구강악안면방사선학회 2006 Imaging Science in Dentistry Vol.37 No.1
Purpose : To find the cause of root curvature by use of panoramic and lateral cephalometric radiograph. Materials and Methods : Twenty six 1st graders whose mandibular 1st molars just emerged into the mouth were selected. Panoramic and lateral cephalometric radiograph were taken at grade 1 and 6, longitudinally. In cephalometric radio graph, mandibular plane angle, ramus-occlusal plane angle, gonial angle, and gonion-gnathion distance (Go-Gn distance) were measured. In panoramic radio graph, elongated root length and root angle were measured by means of digital subtraction radiography. Occlusal plane-tooth axis angle was measured, too. Pearson correlations were used to evaluate the relationships between root curvature and elongated length and longitudinal variations of all variables. Multiple regression equation using related variables was computed. Results : The Pearson correlation coefficient between curved angle and longitudinal variations of occlusal plane-tooth axis angle and ramus-occlusal plane angle was 0.350 and 0.401, respectively (p<0.05). There was no significant correlation between elongated root length and longitudinal variations of all variables. The resulting regression equation was Y=10.209+0.208X_(1)+0.745X_(2) (Y: root angle, X_(1): variation of occlusal plane-tooth axis angle, X_(2): variation of ramus-occlusal plane angle). Conclusion: It was suspected that the reasons of root curvature were change of tooth axis caused by contact with 2nd deciduous tooth and amount of mesial and superior movement related to change of occlusal plane. (Korean J Oral Maxillofac Radiol 2006; 36 : 55-62)
Single Adatom Exchange in Surfactant-Mediated Epitaxial Growth
Yi, Jae Yel,Lee, El Hang,Ko, Young Jo,Park, Seong Ju,Chang, K. J. 東亞大學校附設基礎科學硏究所 1997 基礎科學硏究論文集 Vol.14 No.1
We propose a single adatom exchange mechanism for surfactant-mediated epitaxial growth through first-principles calculations for the Si epitaxy on a si(001) surface covered by an As monolayer. The As segregation is initiated by the exchange of a Si adatom with a sublayer As site, with an activation energy of about 0.1 eV which is much lower than the value of ∼ 1.0 eV for a dimer exchange. Adatom incorporation occurs with minimum surface diffusion, giving rise to a high nucleation density of two-dimensional islands, in good agreement with experiments. [S0031-9007(96)00055-5]
Adaptive neural network controller for the molten steel level control of strip casting processes
Hung-Yi Chen,Shiuh-Jer Huang 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.3
The twin-roll strip casting process is a steel-strip production method which combines continuous casting and hot rolling processes. The production line from molten liquid steel to the final steel-strip is shortened and the production cost is reduced significantly as compared to conventional continuous casting. The quality of strip casting process depends on many process parameters, such as molten steel level in the pool, solidification position, and roll gap. Their relationships are complex and the strip casting process has the properties of nonlinear uncertainty and time-varying characteristics. It is difficult to establish an accurate process model for designing a model-based controller to monitor the strip quality. In this paper, a model-free adaptive neural network controller is developed to overcome this problem. The proposed control strategy is based on a neural network structure combined with a sliding-mode control scheme. An adaptive rule is employed to on-line adjust the weights of radial basis functions by using the reaching condition of a specified sliding surface. This surface has the on-line learning ability to respond to the system’s nonlinear and time-varying behaviors. Since this model-free controller has a simple control structure and small number of control parameters, it is easy to implement. Simulation results, based on a semiexperimental system dynamic model and parameters, are executed to show the control performance of the proposed intelligent controller. In addition, the control performance is compared with that of a traditional PID controller.