• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.479-482
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• 2008

In order to more closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, the thermal-fluid characteristics of high current vacuum arcs were calculated by a commercial multiphysics package, ANSYS, in order to obtain Joule heat, Lorentz force and the interactions with flow variables. We assumed the diffused-mode arc within an AMF vacuum interrupter. It was found with four different currents that the temperature distributions on the anode surface are diffused uniformly without concentration in 7kA for both types (cup and coil-type). But the arc plasma transition and an increase of thermal flux density for increasing the applied current have caused the change of temperature distributions on the anode surface. We should need further studies on the two-way coupling method and radiation model for arc plasmas in order to accomplish the advanced analysis method for multiphysics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.10
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• pp.1048-1054
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• 2004

The Passive acoustic control is used in various fields, such as structures, automobiles, aircraft and so on. It is used in variety of acoustic field with the absorbing material, as one of the methods which can control the acoustic in optional space. In that case of passive control using this absorption material, it would be important to maximize the control performance of material property, numbers, geometry shape and the attached location of boundary area of the absorbing material. But realistically these variables, specially material Property, have no broad choice. Therefore, the position of absorbing material is the most important variable. In this study, we use the optimization method to minimize acoustic energy of optional space in the interest frequency attaching some absorbing materials to the boundary area. For analysis and optimization, this study uses the FEA and the conjugate gradient method. This optimization process is very efficient and useful in the passive acoustic control.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.11
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• pp.1645-1650
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• 2015

This paper presents the 3-dimensional electromagnetic field analysis method and correction of sensor distortion that is used by a motor speed sensor. The magnetic sensors are being expanded due to lower price than the other speed sensors such as resolver and encoder. Magnetic sensor generates sine and cosine waves when the motor rotates. However, the sine and cosine signals are distorted due to magnetic noise, which makes the angle error of the sensor, generated near by the Hall element. This paper defines an optimal design variables by using the Taguchi method to minimize output distortion of the magnetic sensor and permanent magnet. To enhance reliability of the magnetic position sensor from sensitivity error, assembly amplitude mismatch and the electrical angle, 3-Dimensional electromagnetic finite element method and correction algorithm errors were performed in due of the magnetic sensor in order to improve the quality of the initial production model.

• Korean Journal of Childcare and Education
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• v.11 no.2
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• pp.5-20
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• 2015

The purpose of this research is to introduce the fundamental data to develop a program to educate parents properly. To do so, the research investigates the relationship between the father's personal variables and the child's creative personality and emotional intelligence, and searches for what variable shave a significant influence on the balanced growth of a child among a father's personal variables. The participants of study were 200 children of 3~5 years old enrolled in kindergarten or child care centers located in mostly DaeGu city and GyeongBuk provinces. The research applied two tools by measuring the child's creative personality, and observing test paper for a child's emotional intelligence. The data was analyzed by the ANOVA test, Scheff$\acute{e}$ s post-hoc test, Pearson's product moment correlation test and multiple regression analysis. In subordinate variables of a child's creative personality, significance difference was discernable partly with the father's salary and education levels. However, there was no significance difference with the father's age. Especially, the positive influence of the father's education level is apparent on the entire child's creative personality variables, uniqueness and imaginative amusement. Influence Emotional self-awareness shows on entire creative personality variables, uniqueness, diverse interest and imaginative amusement. Emotional awareness in others influences on diverse interest, imaginative amusement. Others emotional control influences positively on entire creative personality. The results of this study suggest that the child's emotional intelligence are significant method to improve the child's creative personality in the education field.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.15-28
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• 1998

As an alternative for solving the incompressible Navier-Stokes equations, we present a vorticity-based integro-differential formulation for vorticity, velocity and pressure variables. One of the most difficult problems encountered in the vorticity-based methods is the introduction of the proper value-value of vorticity or vorticity flux at the solid surface. A practical computational technique toward solving this problem is presented in connection with the coupling between the vorticity and the pressure boundary conditions. Numerical schemes based on an iterative procedure are employed to solve the governing equations with the boundary conditions for the three variables. A finite volume method is implemented to integrate the vorticity transport equation with the dynamic vorticity boundary condition . The velocity field is obtained by using the Biot-Savart integral derived from the mathematical vector identity. Green's scalar identity is used to solve the total pressure in an integral approach similar to the surface panel methods which have been well-established for potential flow analysis. The calculated results with the present mettled for two test problems are compared with data from the literature in order for its validation. The first test problem is one for the two-dimensional square cavity flow driven by shear on the top lid. Two cases are considered here: (i) one driven both by the specified non-uniform shear on the top lid and by the specified body forces acting through the cavity region, for which we find the exact solution, and (ii) one of the classical type (i.e., driven only by uniform shear). Secondly, the present mettled is applied to deal with the early development of the flow around an impulsively started circular cylinder.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.535-543
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• 2014

In the robust optimization field, the robustness of the objective function emphasizes an insensitive design. In general, the robustness of the objective function can be achieved by reducing the change of the objective function with respect to the variation of the design variables and parameters. However, in conventional methods, when an insensitive design is emphasized, the performance of the objective function can be deteriorated. Besides, if the numbers of the design variables are increased, the numerical cost is quite high in robust optimization for nonlinear programming problems. In this research, the robustness index for the objective function and a process of robust optimization are proposed. Moreover, a method using the supremum of linearized functions is also proposed to reduce the computational cost. Mathematical examples are solved for the verification of the proposed method and the results are compared with those from the conventional methods. The proposed approach improves the performance of the objective function and its efficiency.

• The Korean Journal of Rehabilitation Nursing
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• v.3 no.2
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• pp.181-195
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• 2000

The purpose of this study is to find out the effects of personal characteristics, social support, depression, and metamemory on the older adults' memory performances. The subjects of the study consisted of 95 older adults over the age of 60 who are living in Busan. Some data were collected by means of the interview method, using questionnaires for metamemory (MIA questionnaire by Dixon, et al., 1988), and depression(GDS by Yesavage and Sheikl, 1986), social resoueces(Duke university, 1978), family support(Hyun-Sook Kang, 1985). The other data were collected by the testing method on the memory performance such as the immeadiate word recall task, the delayed word recall task, the word recognition task(Elderly Verbal Learning Test by Kyung Mi Choi, 1998), and the face recognition task(Face Recognition Task tool developed by Hye-Sook Min). The results of this study were as follows; 1. The level of metamemory is 3.4 points in the 5 point scale, the grades of the task and the achievement are relatively high and the grades of the change, the control, and the anxiety are relatively low in the sub-concepts. 2. Metamemory have significant relation with age(r=-.44), educational attainment(r=.46), depression(r=-.58), family support(r=.20), social resources(r=.20). 3. The significant variables to predict older adults' metamemory are educational attainment(22%), sex(11%), age (8.3%), depression(4.7%), and illness state(3%). 4. The strong variables to predict memory performances are metamemory, age, depression, social resources, educational attainment, illness state, and limitation of daily living activity related to illness. In conclusion, the enhancement strategies of metamemory and the social support and the prevention or reduction of depression are necessary to increase older adults' memory performances. Ultimately in this respect nurses' roles are very important in developing and performing some intervention programs for old adults' memory improvement, which have significant meanings in the field of nursing science.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.12
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• pp.51-58
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• 1993

This paper presents a design of the fuzzy decision maker which infers set value for fuel rate in the rotary kiln of making CaO. The fuzzy decision maker proposed are divided into two groups whose functions are different each other. The one operates when production demand is constant. The other deals with the status of varying production demand. We have chosen several variables used for composing condition and action part by investigating ingerent features of the rotary kiln and skilled operators`manual method of inferring fuel rate. Membership function of each variable was designed by analyzing experimental data and field data collected during two months. On-line operation with fuzzy rules suggested was done safely like human operators' action.

• Structural Monitoring and Maintenance
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• v.7 no.2
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• pp.85-107
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• 2020

Dynamic responses of porous piezoelectric and metal foam nano-size plates have been examined via a four variables plate formulation. Diverse pore dispersions named uniform, symmetric and asymmetric have been selected. The piezoelectric nano-size plate is subjected to an external electrical voltage. Nonlocal strain gradient theory (NSGT) which includes two scale factors has been utilized to provide size-dependent model of foam nanoplate. The presented plate formulation verifies the shear deformations impacts and it gives fewer number of field components compared to first-order plate model. Hamilton's principle has been utilized for deriving the governing equations. Achieved results by differential quadrature (DQ) method have been verified with those reported in previous studies. The influences of nonlocal factor, strain gradients, electrical voltage, dynamical load frequency and pore type on forced responses of metal and piezoelectric foam nano-size plates have been researched.

• Transactions of Materials Processing
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• v.7 no.3
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• pp.225-232
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• 1998

This article is aimed primarily at establishing a process planning method for complex circular shells. For the deep drawing of complex shaped shell, the optimum process design is required to reduce the trial cost improve the quality, increase the productivity and shorten the delivery. The present approach which is related to the optimum process planning is based on the empirical knowledge through trial and error in the industrial field. In order to check the validity and the effectiveness of proposed work a sample process design has been applied to the multi-stepped deep drawing of com-plex shell considering the process variables such as drawing rate radius and blank development. In particular the difference between the limiting drawing rate and to optimum drawing rate has been discussed and the usefulness of present suggestion has been shown.