• Imaging Science in Dentistry
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• 제31권3호
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• pp.145-151
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• 2001

Purpose : To investigate the hypothesis that the morphology of the articular eminence of the temporomandibular joint is a predisposing factor for disc displacement. Materials and Methods: MR images of 126 temporomandibular joints in 94 patients were analyzed to assess for morphology of the articular eminence and disc displacement. The displaced disc was further categorized as disc displacement with reduction (DDWR) and disc displacement without reduction (DDWOR). The morphology of the articular eminence was classified into four types; box, sigmoid, flattened, and deformed. The relationship between the four types of shape of the articular eminence and the two types of disc position was assessed. Results: In the DDWR and DDWOR groups, the morphology of articular eminence were a box type in 40.5%, a sigmoid type in 30.2%, a flattened type in 24.6%, and a deformed type in 4.7%. The box type of the articular eminence were 34.3% in the DDWR group and 42.9% in the DDWOR group. The sigmoid type of the articular eminence were 34.3% in the DDWR group and 28.6% in the DDWOR group. The flattened type of the articular eminence were 28.6% in the DDWR group and 23.1 % in the DDWOR group. The deformed type of articular eminence were 2.9% in the DDWR group and 5.5% in the DDWOR group. Conclusion: Disc displacement is more likely to be found in the temporomandibular joints with a box-shaped articular eminence. It can be considered that shape of the articular eminence is related to the development of disc displacement.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.275-278
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• 1995

In this paper, we consider a dynamic shape control problem with an example of controlling a flexible beam shape. Mathematical formulations are obtained by employing the Green's function approach. Necessary conditions for optimality are derived by considering the quadratic performance criteria. Numerical results for both of the dynamic and the static cases are obtained and compared.

• Wind and Structures
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• 제35권4호
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• pp.243-253
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• 2022

The conformal mapping method (CMM) has been broadly exploited in the study of fluid flows over airfoils and other research areas, yet it's hard to find relevant research in bridge engineering. This paper explores the feasibility of CMM in streamlined box girder bridges. Firstly, the mapping function transforming a unit circle to the streamlined box girder was solved by CMM. Subsequently, the potential flow solution of aerostatic pressure on the streamlined box girder was obtained and was compared with numerical simulation results. Finally, the aerostatic pressure attained by CMM was utilized to estimate the aerostatic coefficient and flutter performance of the streamlined box girder. The results indicate that the solution of the aerostatic pressure by CMM on the windward side is satisfactory within a small angle of attack. Considering the windward aerostatic pressure and coefficient of correction, CMM can be employed to estimate the rate of change of the lift and moment coefficients with angle of attack and the influence of the geometric shape of the streamlined box girder on flutter performance.

• Restorative Dentistry and Endodontics
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• 제25권1호
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• pp.91-108
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• 2000

Most of cervical abrasion and erosion lesions show gingival margin where the cavosurface angle is on cementum or dentin. Composite resin restoration of cervical lesion shrink toward enamel margin due to polymerization contraction. This shrinkage has clinical problem such as microleakage and secondary caries. Several methods to diminish contraction stress of composite resin restoration, such as modifying cavity form and building up restorations in several increments have been attempted. The purpose of this study was to compare polymerization contraction stress of composite resin in Class V cavity subjected to cavity forms and placement methods. In this study, finite element model of 5 types of Class V cavity was developed on computer tomogram of maxillary central incisor. The types are : 1) Box cavity 2) Box cavity with incisal bevel 3) V shape cavity 4) V shape cavity with incisal bevel 5) Saucer shape cavity. The placement methods are 1) Incisal first oblique incremental curing 2) Bulk curing. An FEM based program for light activated polymerization is not available. For simulation of curing dynamics, time dependent transient thermal conduction analysis was conducted on each cavity and each placement method. For simulation of polymerization shrinkage, thermal stress analysis was performed with each cavity and each placement method. The time-temperature dependent volume shrinkage rate, elastic modulus, and Poisson's ratio were determined in thermal conduction data. The results were as follows : 1. With all five Class V cavifies, the highest Von Mises stress at the composite-tooth interface occurred at gingival margin. 2. With box cavity, V shape cavity and saucer cavity, Von Mises stress at gingival margin of V shape cavity was lower than the others. And that of box cavity was lower than that of saucer cavity. 3. Preparing bevel at incisal cavosurface margin decreased the rate of stress development in early polymerization stage. 4. Preparing bevel at incisal cavosurface margin of V shape cavity increased the Von Mises stress at gingival margin, but decreased at incisal margin. 5. At incisal margin, stress development by bulk curing method was rapid at early stage. Stress development by first increment of incremental curing method was also rapid but lower than that by bulk curing method, however after second increment curing final stress was the same for two placement methods. 6. At gingival margin, stress development by incremental curing method was suddenly rapid at early stage of second increment curing, but final stress was the same for two placement methods.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.327-334
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• 1999

Steel box girders are popular to the Practicing engineers for the its large Pure torsional constant. But closed box girders at-e susceptible to the eccentric loading due to the distortion of the cross section. Distorton of the box girder develops the warping normal stress and transverse flexural stress in the cross section and their magnitudes can be large unless internal diaphragms are installed sufficiently. In this study, stiffness matrix and equivalent nodal force vector are formulated on the basis of displacement method. Shape functions are directly derived from the homogeneous solution of the governing differential equation of the distortion. New finite element formulations were coded into a computer program. Several numerical examples were presented to show the validity of developed program.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.983-987
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• 2003

Vibration causes noise and makes structure unstable. Especially, due to the effort of lightening, deformation of flexible structure is increased in its shape. Just a little disturbance causes vibration and low damping ratio causes residual vibration lasts long time. In this paper, by using a neuro-controller, which is one of the algorithm of adaptive control. we performed adaptive control of flexible cantilever plate and opened box structure with piezoelectric materials. The proposed adaptive vibration control algorithm, a neuro-controller, is proved in its effectiveness by applying to a opened box structure. The neuro-controller was implemented with DSP, and the real-time adaptive vibration control experiment results confirm that neuro-controller is reliable.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1602-1607
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• 2003

Vibration causes noise and sometimes makes structure unstable. Especially, due to the efforts of lightening, deformation of flexible structure is increased in its shape. Just a little disturbance can cause vibration and low damping ratio makes residual vibration last long time. This research is concerned with the model reference neuro-controller design for the vibration suppression of smart structures. By using a model reference neurocontroller, which is one of the algorithms of adaptive control, we performed an adaptive control of flexible cantilever plate and opened box structure with piezoelectric materials. The proposed adaptive vibration control algorithm, a model reference neuro-controller, was proved in its effectiveness by applying to an opened box structure. The model reference neuro-controller is implemented with DSP, and the real-time adaptive vibration control experiment results confirm that the model reference neuro-controller is reliable.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.660-665
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• 2002

A concrete box culvert has been widely used as a typical structure in case of crossing the railroad and highway. Due to the simplicity of it's own shape, in company with the development of computers many studies on the computer-aided automatic design have been continuously carried out. In this paper, an automated design algorithm has been proposed by the analysis of the existed design data of box culverts. From a viewpoint of the users, a data base system has been constructed to carry out the total design process completely through the minimum input data and by means of direct input method on the monitor screen. And an automatic design program for railroad box culverts, in which one-stop process from the structural calculation to the quantity estimation is possible, has been developed.

• 복합신소재구조학회 논문집
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• 제4권1호
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• pp.40-46
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• 2013

This paper presents the design, fabrication and performance of a reinforced concrete beam strengthened by GFRP box plate and its possibility for structural rehabilitations. The load capacity, ductility and failure mode of reinforced concrete structures strengthened by FRP box plate were investigated and compared with traditional FRP plate strengthening method. This is intended to assess the feasibility of using FRP box plate for repair and strengthening of damaged RC beams. A series of four-point bending tests were conducted on RC beams with or without strengthening FRP systems the influence of concrete cover thickness on the performance of overall stiffness of the structure. The parameters obtained by the experimental studies were the stiffness, strength, crack width and pattern, failure mode, respectively. The test yielded complete load-deflection curves from which the increase in load capacity and the failure mode was evaluated.

• Asia pacific journal of information systems
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• 제25권3호
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• pp.563-578
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• 2015

Forecasting daily box-office performance is critical for planning the distribution of marketing resources, and by extension, maximizing profits. For certain movies, the number of viewers increases rapidly at the beginning of their theatrical run, and the increments slow down later. Other movies are not popular in the beginning, but the audience sizes grow rapidly afterward. Thus, the audience attendance of movies grow in different trajectories, which are influenced by various factors including marketing budget, distributors, directors, actors, and word of mouth. In this paper, we propose a method for predicting the daily performance trajectory of running movies based on the hierarchical linear model. More specifically, we focus on the effect of online word of mouth on the shape of the growth curves. We fitted the mean trajectory of the cumulative audience size as a cubic function of time, and allowed the intercept and slope to vary movie-to-movie. Moreover, we fitted the linear slope with a function of online word of mouth predictors to help determine the shape of the trajectories. Finally, we provide performance predictions for individual movies.