• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.9
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• pp.2252-2263
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• 1993

The purpose of this study is to verify the vibration and damping characteristics of elastic-viscoelastic-elastic structures, theoretically and experimentally. The forth-order differential equations of motion are derived for the transverse vibration of three-layered plates with viscoelastic core layer. The equations consider both transverse displacements of the constraining layer and the bare base plate as variable and account for the effect of the transverse normal strain and the shear strain of viscoelastic core layer on the vibration of the plates. Finite difference analysis of the equations and experimental measurements are performed on the three-layered plates of completely free boundary condition. Comparative investigations on the theory and the results of direct frequency analysis of NASTRAN are carried out on the same structures.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.2
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• pp.219-228
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• 2003

The purpose of this study were to examine the characteristics of arm types proposed in the previous study and to present sleeve patterns according size and shape of 4 arm types. 31 direct and indirect items were measured. The subjects for this study were 132 females of twenties. The results were as follows. 1. All of the direct measurements showed significant difference by the arm types. especially at the front armhole part. Such a.: the items of arm gradients, armhole sizes belong to the indirect measurements made clear difference also. 2. By the discriminant analysis, 9 items including underarm length, front armhole girth, upper arm girth, degree of elbow point-wrist point discriminated arm type by the hit ratio of 90.4% Item related to shape of arm rather than size made a sharp distinction. 3. Through the examination of existing patterns and wearing tests on the subjects among 4 groups, sleeve patterns classified by the arm type were suggested.

• Korean Journal of Human Ecology
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• v.16 no.2
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• pp.259-272
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• 2007

The purpose of this study was to investigate the effect of couples' self-differentiation by marital satisfaction according to couple's gender. The participants of the present study were 728 couples who lived in Chonbuk province. The data were collected by self-administered questionnaire method. Self-differentiation scale was consisted of such factors as emotional reactivity, I-position, emotional cut-off and fusion with others. The results of this research were as follows: First, there was significant difference in the level of total self-differentiation between husbands and wives. Second, there was significant difference in the levels of marital conflict and of marital satisfaction to levels of self differentiation. Third, self differentiation in both husbands and wives had an direct effect on marital satisfaction and stability through marital conflict. Fourth, marital conflict in both husbands and wives had a direct effect on marital satisfaction.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.3
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• pp.180-185
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• 2005

Microstrip antennas generally have a lot of advantages that are thin profile, lightweight, low cost, and conformability to a shaped surface application with integrated circuitry. In addition to military applications, they have become attractive candidates in a variety of commercial applications such as mobile satellite communications, the direct broadcast system (DBS), global positioning system (GPS), and remote sensing. Recently, many of the researches have been achieved for improving the impedance bandwidth of microstrip antennas. The basic form of the microstrip antenna, consisting of a conducting patch printed on a grounded substrate, has an impedance bandwidth of $1\~2\%$. For improvement of narrow bandwidth of microstrip patch, we were designed U-slot microstrip patch antenna in this paper. This antenna had wide bandwidth for all personal communication services (PCS) and IMT-2000. For the design of U-slot microstrip patch antenna using a finite difference time domain(FDTD) method. This numerical method could get the frequency property of U-slot patch antenna and the electromagnetic fields of slots.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.671-677
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• 2003

Two-dimensional direct numerical simulation of the edge-tones by the finite difference lattice Boltzmann method (FDLBM) is presented. We use a new lattice BGK compressible fluid model that has an additional term and allow larger time increment comparing the conventional FDLBM, and also use a boundary fitted coordinates. We have succeeded in capturing very small pressure fluctuations result from periodically oscillation of jet around the edge. That pressure fluctuations propagate with the sound speed. It is clarified that the sound wave generated in rather wide region and individual vortices do not affect the sound wave propagation.

• Journal of Welding and Joining
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• v.16 no.3
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• pp.141-147
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• 1998

Design sensitivity analysis of a vehicle system is an essential tool for design optimization and trade-off studies. Most optimization algorithms require the derivatives of cost and constraint function with respect to design in order to calculate the next improved design. This paper presents an efficient algorithm application for the design sensitivity analysis, using the direct differentiation method. A mounting area of suspension that welded on chassis frame is analyzed to show the validity and the efficiency of the proposed method. A mounting area of suspension that welded on chassis frame is analyzed to show the validity and the efficiency of the proposed method.

• Structural Engineering and Mechanics
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• v.53 no.2
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• pp.249-260
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• 2015

Damage detection based on a reference set of measured data usually has the problem of different environmental temperature in the two sets of measurements, and the effect of temperature difference is usually ignored in the subsequent model updating. This paper attempts to identify the structural damage including the temperature difference with artificial measurement noise. Both local damages and the temperature difference are identified in a gradient-based model updating method based on dynamic response sensitivity. The sensitivities of dynamic response with respect to the system parameters and temperature difference are calculated by direct integration method. The measured dynamic responses of the structure from two different states are used directly to identify the structural local damages and the temperature difference. A single degree-of-freedom mass-spring system and a planar truss structure are studied to illustrate the effectiveness of the proposed method.

• Tribology and Lubricants
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• v.14 no.1
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• pp.23-27
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• 1998

The characteristics of friction in direct acting OHC vane train system have been investigated by the comparison of experimental and theoretical results. A modified friction model was presented to calculate the friction force at cam/tappet contact. A simple experimental system was evaluated to measure the friction force and the camshaft driving torque. The friction force was measured by using the dynamic loadcell. Good agreement was found between theoretical and experimental results in friction force, but there was a little difference in driving torque.

• The korean journal of orthodontics
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• v.20 no.2
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• pp.283-291
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• 1990

The purpose of this study was to measure and compare tensile and shear strength for 4 types of new direct-bonding brackets and same brackets after recycling and to evaluate the change of bracket slot width after recycling. Four types of new direct-bond brackets were bonded to recently extracted human premolar teeth and the tensile and shear strength was measured by Universal Testing Machine. The brackets were recycled by chemical process and the tensile and shear test was repeated. To evaluate the change of the bracket slot width, slot width was measured by the Topcon Universal Measuring Microscope before and after recycling. Following results were obtained: 1. There was no satistically significant difference between the tensile and shear strength of recycled brackets and those of new brackets. 2. In both new and recycled brackets, the tensile and shear strength of perforated base bracket was lower than those of photoetched, foilmesh and contou-lok mesh base brackets. (P<0.01) 3. There was no statistically significant difference in bonding strengths of control group bonded only once and two times. 4. There was no statistically significant difference in the change of the bracket slow width after recycling process. 5. Of the failure, the combination type (58%) in the tensile strength and the tooth adhesive interface (65%) in the shear strength was the most common type.

• The Mathematical Education
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• v.46 no.2 s.117
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• pp.173-192
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• 2007

We define mathematical learning as a process of overcoming framing difference of teachers and students, two main subjects in a mathematics class. We have reached this definition to the effect that we can grasp a mathematical classroom per so and understand students' mathematical learning in the context. We could clearly understand the process in which the framing differences are overcome by analyzing mutual negotiation of informants in specific cultural models, both in its form as well as in its meaning. We review both of the direct and indirect forms of negotiation while keeping track of 'evolution of subject' in terms of content of negotiation. More specifically, we discuss direct negotiation briefly and review indirect negotiation from three distinct themes of (1) argument structure, (2) revoicing, and (3) development patterns and narrative structure of proof. In addition, we describe the content of negotiation under the title of 'Evolution of Subject.' We found that major modes of mutual negotiation are inter-reference and appropriation while the product of continued negotiation is inter-resemblance.