• The Journal of Advanced Prosthodontics
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• v.11 no.3
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• pp.169-178
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• 2019

PURPOSE. While dental implants have displayed high success rates, poor mechanical fixation is a common complication, and their biomechanical response to occlusal loading remains poorly understood. This study aimed to develop and validate a computational model of a natural first premolar and a dental implant with matching crown morphology, and quantify their mechanical response to loading at the occlusal surface. MATERIALS AND METHODS. A finite-element model of the stomatognathic system comprising the mandible, first premolar and periodontal ligament (PDL) was developed based on a natural human tooth, and a model of a dental implant of identical occlusal geometry was also created. Occlusal loading was simulated using point forces applied at seven landmarks on each crown. Model predictions were validated using strain gauge measurements acquired during loading of matched physical models of the tooth and implant assemblies. RESULTS. For the natural tooth, the maximum vonMises stress (6.4 MPa) and maximal principal strains at the mandible ($1.8m{\varepsilon}$, $-1.7m{\varepsilon}$) were lower than those observed at the prosthetic tooth (12.5 MPa, $3.2m{\varepsilon}$, and $-4.4m{\varepsilon}$, respectively). As occlusal load was applied more bucally relative to the tooth central axis, stress and strain magnitudes increased. CONCLUSION. Occlusal loading of the natural tooth results in lower stress-strain magnitudes in the underlying alveolar bone than those associated with a dental implant of matched occlusal anatomy. The PDL may function to mitigate axial and bending stress intensities resulting from off-centered occlusal loads. The findings may be useful in dental implant design, restoration material selection, and surgical planning.

• Structural Engineering and Mechanics
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• v.55 no.6
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• pp.1121-1137
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• 2015

High powered computers and engineering computer systems allow designers to routinely simulate complex physical phenomena. The presented work deals with the analysis of two finite element method optimization techniques (First Order Method-FOM and Subproblem Approximation Method-SAM) implemented in the individual Design Optimization module in the Ansys software to analyze the behavior of real problems. A design optimization is a difficult mathematical process, intended to find the minimum or maximum of an objective function, which is mostly based on iterative procedure. Using optimization techniques in engineering designs requires detailed knowledge of the analyzed problem but also an ability to select the appropriate optimization method. The methods embedded in advanced computer software are based on different optimization techniques and their efficiency is significantly influenced by the specific character of a problem. The efficiency, robustness and accuracy of the methods are studied through strictly convex two-dimensional optimization problem, which is represented by volume minimization of two bars' plane frame structure subjected to maximal vertical displacement limit. Advantages and disadvantages of the methods are described and some practical tips provided which could be beneficial in any efficient engineering design by using an optimization method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.73-78
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• 2019

This paper proposes polynomial-time rule for maximum weighted independent set(MWIS) problem that is well known NP-hard. The well known distributed algorithm selects the maximum weighted node as a element of independent set in a local. But the merged independent nodes with less weighted nodes have more weights than maximum weighted node are frequently occur. In this case, existing algorithm fails to get the optimal solution. To deal with these problems, this paper constructs maximum weighted independent set in local area. Application result of proposed algorithm to various networks, this algorithm can be get the optimal solution that fail to existing algorithm.

• Journal of Biomedical Engineering Research
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• v.37 no.2
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• pp.90-103
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• 2016

This research was aimed to analyze load sharing ratios between cortical shell and trabecular bone of a degraded lumbar vertebra with aging, and also evaluate elastic moduli assigned into an FE model, using finite element method. For the better analysis of trabecular bone, effective elastic moduli, that is, nominal elastic moduli divided by the volumetric porosities was used. The elastic moduli of the cortical shell suitable for the trabecular bone were obtained from the equations on the basis of idealized stress-strain relations, including areal porosities. To minimize numerical errors, p-element was used. Using eight parameters that refer to some published papers, the geometry of L3 with a removed posterior part. After the constant compressive displacement was applied, the load sharing ratios were obtained by using both every elastic strain energy and every vertical force between two bones in each 8-volume. As results, 1) according to an increase in age from 20-year to 80-year, load sharing ratios of trabecular bone decreased from 55% to 49%; 2) the maximal ratios of each bone were occurred in the mid-plane of centrums and the endplate of cortical shells, respectively; 3) effective elastic moduli assigned into a porous centrum/cortex were found to be adequate; 4) for load sharing ratios, the difference of two methods showed that the total ratios were almost same within less than 1% but the partial ratios at every depth were more or less different each other.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.417-428
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• 2020

Investigations of the commercial aircraft impact effect on nuclear island infrastructures have been drawing extensive attention, and this paper aims to perform the safety assessment of Generation III nuclear power plant (NPP) buildings subjected to typical commercial aircrafts crash. At present Part III, the local damage of the rigid components of aircraft, e.g., engine and landing gear, impacting the steel concrete (SC) structures of NPP containment is mainly discussed. Two typical SC target panels with the thicknesses of 40 mm and 100 mm, as well as the steel cylindrical projectile with a mass of 2.15 kg and a diameter of 80 mm are fabricated. By using a large-caliber air gas gun, both the projectile penetration and perforation test are conducted, in which the striking velocities were ranged from 96 m/s to 157 m/s. The bulging velocity and the maximal deflection of rear steel plate, as well as penetration depth of projectile are derived, and the local deformation and failure modes of SC panels are assessed experimentally. Then, the commercial finite element program LS-DYNA is utilized to perform the numerical simulations, by comparisons with the experimental and simulated projectile impact process and SC panel damage, the numerical algorithm, constitutive models and the corresponding parameters are verified. The present work can provide helpful references for the evaluation of the local impact resistance of NPP buildings against the aircraft engine.

• Microbiology and Biotechnology Letters
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• v.1 no.2
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• pp.75-78
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• 1973

Effects of nitrogen sources, supplement of vitamins and minerals on the accumulation of 5'-inosinic acid by an adenineless mutant of Brevibacterium ammoniagenes were examined. Maximal yield of 5'-inosinic acid was attained by the use of yeast extract. as organic nitrogen source Casamino acid supplemented with $Mn^{＋＋}$, $Zn^{＋＋}$ Ca-D-pantothenate and thiamine HCl could be subsitute for it. Subsequent experiment using the defined medium showed that the concentration of these trace element in the medium affected inosinic acid accumulation markedly. And it was found that the simulataneous addition of $Mn^{＋＋}$ (20$\mu\textrm{g}$1). $Zn^{＋＋}$(10$\mu\textrm{g}$1). thiamine Hcl(10mg/1) and Ca-D-pantothenate (5mg/l) to the defined medium stimulated inosinic acid accumulation, from which 7mg/ml of inosinic acid was obtained.

• Archives of Plastic Surgery
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• v.42 no.3
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• pp.309-315
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• 2015

Background Breast projection is a critical element of breast reconstruction aesthetics, but little has been published regarding breast projection as the firm expander is changed to a softer implant. Quantitative data representing this loss in projection may enhance patient education and improve our management of patient expectations. Methods Female patients who were undergoing immediate tissue-expander breast reconstruction with the senior author were enrolled in this prospective study. Three-dimensional camera software was used for all patient photographs and data analysis. Projection was calculated as the distance between the chest wall and the point of maximal projection of the breast form. Values were calculated for final tissue expander expansion and at varying intervals 3, 6, and 12 months after implant placement. Results Fourteen breasts from 12 patients were included in the final analysis. Twelve of the 14 breasts had a loss of projection at three months following the implant placement or beyond. The percentage of projection lost in these 12 breasts ranged from 6.30% to 43.4%, with an average loss of projection of 21.05%. Conclusions This study is the first prospective quantitative analysis of temporal changes in breast projection after expander-implant reconstruction. By prospectively capturing projection data with three-dimensional photographic software, we reveal a loss of projection in this population by three months post-implant exchange. These findings will not only aid in managing patient expectations, but our methodology provides a foundation for future objective studies of the breast form.

• Bulletin of the Korean Mathematical Society
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• v.57 no.6
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• pp.1351-1365
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• 2020

Let S and T be w-linked extension domains of a domain R with S ⊆ T. In this paper, we define what satisfying the w_R-GD property for S ⊆ T means and what being w_R- or w-GD domains for T means. Then some sufficient conditions are given for the w_R-GD property and w_R-GD domains. For example, if T is w_R-integral over S and S is integrally closed, then the w_R-GD property holds. It is also given that S is a w_R-GD domain if and only if S ⊆ T satisfies the w_R-GD property for each w_R-linked valuation overring T of S, if and only if S ⊆ (S[u])_w satisfies the w_R-GD property for each element u in the quotient field of S, if and only if S_𝔪 is a GD domain for each maximal w_R-ideal 𝔪 of S. Then we focus on discussing the relationship among GD domains, w-GD domains, w_R-GD domains, Prüfer domains, PνMDs and Pw_RMDs, and also provide some relevant counterexamples. As an application, we give a new characterization of Pw_RMDs. We show that S is a Pw_RMD if and only if S is a w_R-GD domain and every w_R-linked overring of S that satisfies the w_R-GD property is w_R-flat over S. Furthermore, examples are provided to show these two conditions are necessary for Pw_RMDs.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.4
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• pp.223-231
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• 2019

A continuum-based design sensitivity analysis(DSA) method is developed for electrostatic problems. To consider high order objective functions, we use 9-node finite element basis functions for analysis and DSA methods. As the design variables are parameterized with B-spline functions, smooth boundary variations are naturally obtained. To solve mesh entanglement problems during the optimization process, a mesh regularization scheme is employed. By minimizing the Dirichlet energy functional, mesh uniformity can be automatically achieved. In numerical examples for maximizing dielectrophoresis forces, the numerical results are compared with well-known electrode geometries and the obtained characteristics are discussed.

• The Journal of the Acoustical Society of Korea
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• v.24 no.7
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• pp.379-386
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• 2005

Among various kinds of hearing aids which have been developed so far. the conventional air conduction hearing aids have some problems such as the acoustic distortion, an howling effect due to acoustic feedback. Another type of hearing aid. the cochlear implant system can be applied to the profound imparied person. However. it shows the disadvantage that there is no possibility of recovery of the acoustic organ such as ossicle. On the other hand. the implantable middle ear heaving device directly vibratos the ossicular chain and has better sound qualify. good cosmetics for appearance. and wide frequency responses so that it can overcome the defects or the conventional hearing aids. In this paper, a mathematical modeling and a momentum equation derivation of the DET has been performed. For the optimization of the structure dimension generating maximal vibrating force of the DET. the computer simulation using a finite element analysis (FEA) software has been performed. Also. the vibrating transducer has been designed to make the frequency characteristics or the transducer be similar to those of the normal middle ear. Through the experimental results, the measured vibration characteristics of the DET has been evaluated to verify the performance for the application to implantable middle ear hearing devices.