• Restorative Dentistry and Endodontics
• /
• v.37 no.3
• /
• pp.136-141
• /
• 2012

Objectives: The maintenance of the healthy periodontal ligament cells of the root surface of donor tooth and intimate surface contact between the donor tooth and the recipient bone are the key factors for successful tooth transplantation. In order to achieve these purposes, a duplicated donor tooth model can be utilized to reduce the extra-oral time using the computer-aided rapid prototyping (CARP) technique. Materials and Methods: Briefly, a three-dimensional digital imaging and communication in medicine (DICOM) image with the real dimensions of the donor tooth was obtained from a computed tomography (CT), and a life-sized resin tooth model was fabricated. Dimensional errors between real tooth, 3D CT image model and CARP model were calculated. And extra-oral time was recorded during the autotransplantation of the teeth. Results: The average extra-oral time was 7 min 25 sec with the range of immediate to 25 min in cases which extra-oral root canal treatments were not performed while it was 9 min 15 sec when extra-oral root canal treatments were performed. The average radiographic distance between the root surface and the alveolar bone was 1.17 mm and 1.35 mm at mesial cervix and apex; they were 0.98 mm and 1.26 mm at the distal cervix and apex. When the dimensional errors between real tooth, 3D CT image model and CARP model were measured in cadavers, the average of absolute error was 0.291 mm between real teeth and CARP model. Conclusions: These data indicate that CARP may be of value in minimizing the extra-oral time and the gap between the donor tooth and the recipient alveolar bone in tooth transplantation.

• The Journal of Korean Association of Computer Education
• /
• v.12 no.5
• /
• pp.49-62
• /
• 2009

The Extra-Curriculum in The Air and Correspondence High School(ACHS), which play a role as an organization of lifelong learning, has not been operating properly for lack of appropriate circumstances and also educational research. So this research applied the Extra-Curriculum on-line contents to ACHS as an example to search for the effective operation solution in ACHS Extra-Curriculum, and derived the implications which are necessary to class operation. According to the implications which are obtained by the analysis of the application result, selected the five main areas in Blended-Learning which are necessary to the operation of ACHS Extra-Curriculum, and developed the direct instruction model by blending the teaching-learning method and strategy which is suitable for the ACHS Extra-Curriculum. Finally, based on these research results, this research developed the Blended-Learning Teaching Model for ACHS Extra-Curriculum by reflecting the peculiarity of ACHS student and characteristics of Extra-Curriculum contents.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.17 no.3
• /
• pp.27-46
• /
• 1992

This paper considers an (r, Q) policy for operation of a multipurpose facility. It is assumed that whenever the inventory level falls below r, the model starts to produce the fixed amount of Q. The facility can be utilized for extra production during idle periods, that is, when the inventory level is still greater than r right after a main production operation is terminated or an extra production operation is finished. But, whenever the facility is in operation for an extra production, the operation can not be terminated for the main production even though the inventory level falls below r. In the model, the demand for the product is assumed to arrive according to a compound Poisson process and the processing time required to produce a product is assumed to follow an arbitary distribution. Similarly, the orders for the extra production is assumed to accur in a Poisson process are the extra production processing time is assumed to follow an arbitrary distribution. It is further assumed that unsatisfied demands are backordered and the expected comulative amount of demands is less than that of production during each production period. Under a cost structure which includes a setup/ production cost, a linear holding cost, a linear backorder cost, a linear extra production lost sale cost, and a linear extra production profit, an expression for the expected cost per unit time for a given (r, Q) policy is obtained, and using a convex property of the cost function, a procedure to find the optimal (r, Q) policy is presented.

• East Asian Journal of Business Economics (EAJBE)
• /
• v.10 no.3
• /
• pp.27-40
• /
• 2022

Purpose - The purpose of this study is to test the impact of job crafting on in/extra-role performance in Chinese context. In addition, it intends to verify the mediating effect of work engagement on the relationship between job crafting and in/extra-role performance. Research design, data, and methodology - Survey data were collected from employees of the companies in Hebei, China, for about two months, from early January 2022 to early March 2022. A total of 300 copies were distributed, and 240 copies were collected (80%), of which 222 copies were used for the final analysis. Data were analyzed for statistical tests of the measurement model and hypotheses using IBM SPSS Statistics 25 and Amos 25. Result - The analysis results are as follows. First, job crafting has a direct effect on work engagement. Second, work engagement increased employees' in/extra-role performance. Third, the mediating effect of work engagement was verified in the relationship between job crafting and employees' in/extra-role performance. Conclusion - This study expands the job demand-resource model by revealing the effect of job crafting, which changes the job given to oneself, on in/extra-role performance. In addition, this study investigated the impact of work engagement on the relationship between job crafting and in/extra-role performance.

• Journal of the Korean Physical Society
• /
• v.80
• /
• pp.20-29
• /
• 2022

We discuss various aspects of anisotropic gravity in (d+D)-dimensional spacetime, where D dimensions are treated as extra dimensions. It is based on the foliation preserving diffeomorphism invariance and anisotropic conformal invariance. The anisotropy is embodied by introducing a factor z which discriminates the scaling degree of the extra D dimensions against the d-dimensional base spacetime and Weyl scalar field which mediates the anisotropic scaling symmetry. There is no intrinsic scale but a physical scale M_* emerges as a consequence of spontaneous conformal symmetry breaking. We discuss interesting lower dimensional gravity theories obtained from our model. In a (d, D) = (2, 2) case, we suggest a UV-complete unitary quantum gravity which might become Einstein gravity in IR. In a certain (2,1) case, we obtain CGHS model. Some vacuum solutions are also obtained and we discuss an issue of 'size separation' between the base spacetime and the extra dimensions. The size separation means large distinction between the scales (e.g. cosmological constant) appearing in the base spacetime and the extra dimensions respectively.

• Journal of Fisheries and Marine Sciences Education
• /
• v.17 no.3
• /
• pp.383-389
• /
• 2005

In this study, we analyzed consumers' extra willingness-to-pay for the organic farmed laver, which recently is related to the increased interests in health. Survey questionnaires, which are targeted the urban consumers and based on the equivalent surplus concept, were intended to calculate extra willingness-to-pay for the organic farmed laver. Payment card format was used as the questionnaires type and tobit model was used for the analysis. Variables used for the analysis are sex, age, region, occupation, number in family and income. The results were that the consumers had extra willness-to-pay of 17.16% on average for the eco-friendly organic farmed laver. The higher the income and the more the family number, the customers had more extra willingness-to-pay.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.1
• /
• pp.184-192
• /
• 1994

The parameters such as Richardson numbers or stability parameters are widely used to account for the extra straining effects due to three-dimensionality, curvature, rotation, swirl and others arising in paractical complex flows. Existing expressions for the extra strain in turbulence models such as $k-{\epsilon}$ models, however, do not satisfy the tensor invariant condition representing the coordinate indifference. In the present paper, considering the characteristics of both the mean strain rate and the mean vorticity, a new parameter to deal with the extra straining effects is proposed. The new parameter has a simple form and satisfies the tensor invariant condition. A semi-quantitative analysis between the present and previous parameters for several typical complex flows suggests that the newly proposed parameter is more general and adequate in representing the extra straining effects than the previous ad-hoc parameters.

• Korean Management Science Review
• /
• v.13 no.3
• /
• pp.163-172
• /
• 1996

According to flying hours, aircraft engines require regular overhaul for preventive maintenance. Because of hostile defense environment of Republic of Korea, the aircraft of republic of Korea Air Force(ROKAF) have been operated at the maximum level of availability and have similar overhaul schedule in several months. The concentration of overhaul schedule in a short period demands additional spare engines far exceeding the spare engines for corrective maintenance. If ROKAF decides to purchase extra engines for the preventive maintenance, the extra engines will be used only for the preventive maintenance and will be excess inventory for the most of aircraft life ccle. Also, the procurement of extra engines is significant investment for ROKAF. To help ROKAF schedule the preventive maintenance without significant spending, this study develops a dynamic programming model that is solvable using an integer programming algorithm. The model provides the number of engines that should be overhauled for a month for multiple periods under given constraints. ROKAF actually used this model to solve a T-59 engine overhaul problem and saved about three billion won at one time. ROKAF plans to use this model continuously for T-59 and other weapon systems. Thus, saving for long term will be significant to ROKAF. Finally, with minor modification, this model can be applied to deciding the minimum number of spare engines for preventive maintenance.

• Journal of Technologic Dentistry
• /
• v.41 no.4
• /
• pp.263-269
• /
• 2019

Purpose: The purpose of this study was to evaluate the internal fitness of prostheses fabricated with non-contact extra-oral scanner and those fabricated with intra-oral video scanner, with a comparative accuracy analyses of their precision and trueness. Methods: A polymethyl methacrylate (PMMA) model was fabricated by replicating a master model. The prostheses in the first group were fabricated based on the PMMA model with an intra-oral video scanner (IVS group). Following the fabrication of work models with Type IV Stone that were based on the PMMA model, the prostheses in the second group were fabricated with a non-contact extra-oral scanner (ENB group). The precision and trueness of the prostheses were calculated from comparisons of the three-dimensional images of the internal surfaces of the prostheses and those of the master model. Kruskal-Wallis tests were used to determine the statistical significance, with the level of type 1 error set at 0.05. Results: Trueness (P < 0.009) and precision (P < 0.001) did not differ significantly between the ENB and IVS groups. The IVS group exhibited lower trueness values and larger precision values than the ENB group. Conclusion: Although no significant differences were found in the internal fitness of the prostheses that were fabricated by the two different scanners, the intraoral video scanner-fabricated prostheses had better trueness, whereas the non-contact extra-oral scanner-fabricated prostheses had better precision.

• Journal of Astronomy and Space Sciences
• /
• v.7 no.2
• /
• pp.73-103
• /
• 1990

Morphological luminosity parameters$(\mu_e,\;r_e,\;\mu_0,\;\alpha^{-1})$ and D/B were estimated from the decomposition of surface brightness distributions of 28 extra galaxies. Decomposition was made using the standard non-linear least square fitting method and we used the seeing convolved model to get the central brightness of these galaxies. Masses and $M/L_B$ were calculated using rotational velocities of these galaxies from the fitting to the generalized Toomre's mass model.