• Journal of the Korean Society for Precision Engineering
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• v.10 no.1
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• pp.114-125
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• 1993

Thermoelastoplastic analysis of a typical device consisting of fixed tube and movable case having an inital clearance in between, which is subjected to pressure and thermal load, has been carried out to examine the cause of malfunction mainly at high temperature condition, and to improve the design. Stresses, deformed shape, interface state and their effects on normal function of case are discussed by using finite element method. The extraction energy can be remarkably reduced by changing the configuration of tube from the present design (Parallel type) to the improved design (Tapered type). This effect has been proved by sustained cyclic function test.

• KSTLE International Journal
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• v.5 no.1
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• pp.7-13
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• 2004

The inclined subsurface cracks in a homogeneous body subjected to a moving compressive load is analyzed with the finite element method (FEM) considering friction on the crack surface. The stress intensity factors for the inclined subsurface cracks are evaluated numerically for various cases such as different inclined angles and changes in the coefficient of friction. The effects of the inclined angle and the coefficient of friction on the stress intensity factor are discussed. The difference between the behaviors of the parallel subsurface crack and those of the inclined subsurface crack is also examined.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.2
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• pp.155-159
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• 2016

Eddy current testing (ECT) is an important nondestructive testing technology for the inspection of flaws in conductive materials. However, this widely used technology is not suitable for inspecting lamination when a conventional pancake coil is used because the eddy current (EC) generated by the pancake coil is parallel to the lamination and will not be perturbed. A new method using a rectangular coil placed vertical to the work piece is proposed for lamination detection. The vertical sections of the rectangular coil induce ECs that are vertical to the lamination and can be perturbed by the lamination. A parametric study of a rectangular coil by finite element analysis was performed in order to examine the capability of generating vertical EC.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.97-102
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• 2012

To predict accurately the breakdown voltage in air at atmospheric pressure, a fully coupled finite element analysis combining the hydrodynamic diffusion-drift equations with Poisson's equation is proposed in the current paper. As three kinds of charged transport particles are nonlinearly coupled with spatial electric fields, the equations should be solved by an iterative numerical scheme, in which secondary effects, such as photoemission and photoionization, are considered. The proposed method has been successfully applied to evaluate the breakdown voltage in circular parallel-plane electrodes. Its validity has been proved through the comparison of the predicted and experimental results. The effects of numerical conditions of the initial charge, photoemission, and background ionization on the discharge phenomena are quantitatively assessed through Taguchi's design of experiment method.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.1
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• pp.27-31
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• 2000

This paper presents the performance evaluation of an HTS transformer. Numerical calculation by finite element method was used to evaluate the performance. BSCCO-2223 HTS tapes and double pancake winding were adopted in this design. Four double pancake windings were used in total. Among them two windings were connected in series for high voltage winding and two windings are connected in parallel for low voltage winding. Propertied of various type of the winding arrangement were examined. Characteristics of the transformer during the transient which was caused by sudden short were simulated. The current limiting effect, temperature rise and resistance growth of the superconducting winding were shown.

• The korean journal of orthodontics
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• v.23 no.2 s.41
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• pp.263-273
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• 1993

The purpose of this study was to analyse the center of resistance of the maxillary first molar using the 3-dimension finite element method. An extracted maxillary first molar of normal shape and average root length was selected and sectioned every 1.5mm parallel to the cementoenamel junction. Each section was traced and digitized to construct 3-D finite element model of the maxillary first molar. After a certain magnitude of counterbalancing moment(M) was applied to the tooth, a varying single force(F) of distomesial direction was applied to a certain point of th tooth until the tooth was translated. The force producing translation(Ft) was substituted to the equation ${\Delta}d=M/Ft$ to calculate the center of resistance of the maxillary first molar. And reducing the alveolar bone level 1.68mm, and 3.36mm below to the cementoenamel junction, the tooth movement was analysed to see the effect of reducing the alveolar bone level to the location of the center of resistance. The results were as follows ; 1. The center of resistance of the maxillary first molar was 3.72mm apical, 1.10mm buccal, and 0.71mm mesial to the geometric center of the horizontally sectioned surface at the cementoenamel junction. This point was 0.36mm apical, 1.20mm buccal, and 0.71mm mesial to the trifurcation point, indicating that it was not on the tooth root. 2. As the alveolar bone level was reduced, the center of resistance of the maxillary first molar was moved to the apical direction.

• International Journal of CAD/CAM
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• v.3 no.1_2
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• pp.51-60
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• 2003

The growth of the World Wide Web and the advances in high-speed network access have greatly changed existing CAD/CAE environment. The WWW has enabled us to share various distributed product data and to collaborate in the design process. An international standard for the product model data, STEP, and a standard for the distributed object technology, CORBA, are very important technological components for the interoperability in the advanced design and manufacturing environment. These two technologies provide background for the sharing of product data and the integration of applications on the network. This paper describes a distributed CAD/CAE environment that is integrated on the network by CORBA and product model data standard STEP. Several prototype application modules were implemented to verify the proposed concept and the test result is discussed. Finite element analysis server are further distributed into several frontal servers for the implementation of distributed parallel solution of finite element system equations. Distributed computation of analysis server is also implemented by using CORBA for the generalization of the proposed method.

• Journal of Electrical Engineering and Technology
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• v.3 no.4
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• pp.552-558
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• 2008

Optimal design of the direct-driven Permanent Magnet(PM) wind generator, combined with F.E.A(Finite Element Analysis) and Genetic Algorithm(GA), has been performed to maximize the Annual Energy Production(AEP) over the entire wind speed characterized by the statistical model of wind speed distribution. Particularly, the proposed parallel computing via internet web service has contributed to reducing excessive computing times for optimization.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.353-364
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• 1998

This paper describes the design processes and evaluation results of a small-sized six-axis force/torque sensor. The new six-axis force/torque sensor including S-type structure has been developed using a parallel plate structure as a basic sensing element. In order tominimize coupling errors, the location of strain gages has been determined based on the finite element analysis and the connections of strain gages have been made such that the bridge circuit with 4 strain gages becomes balanced. Several design modifications result in a similar strain sensitivity for six-axis forces and moments, and the reduced coupling errors of 2.6% FS between each forces and moments. Calibration test results show that the six-axis load cell developed which has light weight of 135g and the maximum capacities of 196 N in forces and 19.6 N.m in moments is estimated to be within 7.1% FS in coupling error.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.2
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• pp.127-153
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• 2012

This paper presents an advanced computational method for the prediction of the responses in the frequency domain of general linear dissipative structural-acoustic and fluid-structure systems, in the low-and medium-frequency domains and this includes uncertainty quantification. The system under consideration is constituted of a deformable dissipative structure that is coupled with an internal dissipative acoustic fluid. This includes wall acoustic impedances and it is surrounded by an infinite acoustic fluid. The system is submitted to given internal and external acoustic sources and to the prescribed mechanical forces. An efficient reduced-order computational model is constructed by using a finite element discretization for the structure and an internal acoustic fluid. The external acoustic fluid is treated by using an appropriate boundary element method in the frequency domain. All the required modeling aspects for the analysis of the medium-frequency domain have been introduced namely, a viscoelastic behavior for the structure, an appropriate dissipative model for the internal acoustic fluid that includes wall acoustic impedance and a model of uncertainty in particular for the modeling errors. This advanced computational formulation, corresponding to new extensions and complements with respect to the state-of-the-art are well adapted for the development of a new generation of software, in particular for parallel computers.