• Korean Journal of Materials Research
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• v.9 no.9
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• pp.919-925
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• 1999

Grain boundary characteristics and corrosion behavior of Alloy 600 material were investigated using the concept of grain boundary control by thermomechanical treatment(TMT). The grain boundary character distribution (GBCD) was analyzed by electron backscattered diffraction pattern. The effects of GBeD variation on intergranular at tack(JGA) and primary water stress corrosion cracking(PWSeC) were also evaluated. Changes in the fraction of coinci dence site lattice(CSL) boundaries in each cycle of TMT process were not distinguishable, but the total eSL boundary frequencies for TMT specimens increased about 10% compared with those of the commercial Alloy 600 material. It was found from IGA tests that the resistance to IGA was improved by TMT process. However, it was found from PWSCC test that repeating of TMT cycles resulted in the gradual decrease of the time to failure and the maximum load due to change in grain boundary characteristics, while the average crack propagation rate of primary crack increased mainly due to suppression of secondary crack propagation. It is considered that these corrosion characteristics in TMT specimens is attributed to 'fine tuning of grain boundary' mechanism.

• Magazine of the Korean Society of Agricultural Engineers
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• v.28 no.4
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• pp.49-56
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• 1986

This study was carried out to investigate mechanical characteristics of the uniformly loaded skew-plate at 4 kinds of boundary condition : i) all edges are clamped (BC-1) , ii) all edges are simply supported (BC- 2), iii) two opposite edges are clamped and the other two edges are free (BC-3), and iv )two opposite edges are simply supported and the other two edges are free (BC-4). Various skew angles, 0$^{\circ}$, 10$^{\circ}$, 15$^{\circ}$, 30$^{\circ}$, 40: 45: and 60, of the plate were tested for the above boundary conditions. Resutts obtained from the study are summarized as follows ; 1.The lateral displacement at the center of a skew- plate was decreased as the skewangle increased at all of the boundary conditions. The decrements of the conditions of BC-3 and BC-4 were considerable. And, difference of the displacement between the boundary conditions was decreased as the skew-angle was increased. 2. X-moments (to the Y-axis) at the center of a skew- plate and the minimum principal moments were shown as a similar pattern of change with respect to the skew-angle variation between BC-i and BC-2 and between BC-3 and BC-4, and the pattern of change at the conditions of BC-3 and BC-4 were shown higher rates than those for the conditions of BC-i and BC-2 3.Y-moments (to the X- axis) at the center of a skew-plate and the maximum principal moment were decreased as the skew-angle increased in a similar pattern at all of the boundary conditions. 4.X-moments at the obtuse angle side of a skew-plate were shown as a parabolic pattern of change (frist increased after then decreased) as the skew-angle increased, and a skew-angle resulting the maximum absolute moment was depended on the boundary conditions. 5.Y-moments at the obtuse angle side of a skew-plate were affected by the skewangle much more at the boundary condtions of BC-2 and BC-4 than at the conditions of BC-i and BC-3. 6.Maximum principal moments at the obtuse angle side of a skew-plate at the skew angle of 40$^{\circ}$- 45$^{\circ}$ were resulted almost the same value at all of the boundary conditions .

• Proceedings of the Korean DIstribution Association Conference
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• 2007.08a
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• pp.3-26
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• 2007

Recently, both scholars and marketers have asserted the importance of boundary spanning behaviors, such as external representation, being vocal advocates to outsiders of the organization's image, goods, and services, internal influence, taking individual initiative in communications to the firm and co-workers to improve service delivery by the organization, co-workers, and oneself, and service delivery, serving customers in a conscientious, responsive, flexible, and courteous manner. However, there is lack of study dealing with bourdary spanning behaviors bewteen organizational dyads, in which boundary spanning behaviors are expected to have important roles. The objectives of this paper is to investigate these important concerns with prior research by developing a theoretical model predicting how distinct buyer's boundary spanning behaviors occur. To be concrete, this paper develops a seller characteristics-based model of the attitudinal antecedents of three conceptually distinct forms of boundary spanning behaviors, and tests the hypothesized differential effects of seller characteristics on the three forms of boundary spanning behaviors, and investigates the extent to which these relationships are mediated by relationship satisfaction and organizational commitment. For the purpose of empirical testing, 420 respondents of leading automobile dealers, dining franchisees, industrial material retailers in Korea were surveyed and the analysis utilizing structural equation model indicated that communication quality, fairness, and marketing program dynamism had positive effects on buyer's boundary spanning behaviors via relationship satisfaction and organizational commitment. In addition, boundary spanning behaviors occurred more in contractural and corporate distribution channel than in conventional distribution channel.

• Tribology and Lubricants
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• v.26 no.1
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• pp.7-13
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• 2010

This experimental study presents tribological characteristics under boundary lubrication contacts associated with electrorheolocal (ER) fluid. ER fluid is prepared by using phosphorated starch particles and silicone oil. Experimental apparatus of tribological tester is designed and constructed to evaluate tribological characteristics of pin specimens. Wear tests under boundary lubrication of ER fluid are experimentally performed under consideration of several operational factors such as normal load, sliding distance, sliding speed and specimen materials: steel, copper and aluminum. After wear test, microscopic surface changes of the worn pin specimens are analyzed in order to investigate measured wear characteristics by using the scanning electron microscope (SEM) as well as surface profilometer. In addition, the chemical wear characteristics are investigated by using energy dispersive x-ray spectroscopy (EDS). Moreover, friction coefficient measurements under different materials of pin specimens are conducted for the tribological investigations. In order to verify the effect of starch phosphate particles in ER fluid, the wear test results with ER fluid are compared with test results with only silicone oil. The results clearly present that the phosphorated starch based ER fluid shows the stabilized wear as well as friction characteristics after run-in operations, but the wear rate under ER fluid is increased.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.67-75
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• 2006

A fully nonlinear model accounting for swirling effect has been applied in analyzing the dynamic response for a classical swirl injector. The current work applied highly accurate Boundary Element Methods (BEMs) in assessing its static and dynamic characteristics. On the basis of moving surface treatment method and surface instability study, which are obtained from the previous static characteristics analysis in pressure-swirl injectors, this work was expanded for analyzing the dynamics of a classical swirl injector. The dynamic response through injector components for disturbed inflow condition was investigated. The modified code was validated from comparison with the theoretical result for a typical swirl injector. Clearly the simulated result shows the interesting characteristics of swirl injectors to provide either amplification or damping of the input disturbance through each component. These results give promise in applying the current model to nonlinear dynamic characteristics of swirl injectors.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.10
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• pp.1057-1064
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• 2008

In this paper, static and oscillatory instability of nanopipes conveying fluid and modelled as a thin-walled beam is investigated. Effects of boundary conditions and non-classical transverse shear and rotary inertia are incorporated in this study. The governing equations and the three different boundary conditions are derived through Hamilton's principle. Numerical analysis is performed by using extend Galerkin method which enables us to obtain more exact solutions compared with conventional Galerkin method. Variations of critical flow velocity for different boundary conditions of carbon nanopipes are investigated and pertinent conclusion is outlined.

• Transactions of Materials Processing
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• v.8 no.4
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• pp.384-392
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• 1999

In metal forming, there are problems with recurrent geometric characteristics without explicitly prescibed boundary conditions. In such problems, so-called recurrent boundary conditions must be introduced. In this paper, as a practical application of the proposed method, the precision cold forging of a helical gear has been simulated by a three-dimensional rigid-plastic finite element method and compared with the experiment. The application of recurrent boundary conditions to helical gear forging analysis is proved to be effective and valid. the elastic stress analysis of the die for helical gear forging has been calculated by using the nodal force at the final stage obtained from the rigid-plastic finite element analysis. In order to obtain more precise gear products, the elastic analysis of the die after release of punch and the elastic spring-back analysis of product after ejection have been performed, and the final dimension of the computational product has been in good agreement with that of the experimental product.

• Journal of Mechanical Science and Technology
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• v.15 no.5
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• pp.555-561
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• 2001

A new approach to analyze the multi-domain acoustic system divided and enclosed by flexible structures is presented in this paper. The boundary element formulation of the Helmholtz integral equation is used for the internal fields and the finite element formulation for the structures surrounding the fields. We developed a numerical analysis program for the structural-acoustic coupling problems of the multi-domain system, in which boundary conditions such as the continuity of normal particle velocity and sound pressure in the structural interfaces between Field 1 and Field 2 are not needed. The validity of the numerical analysis program is verified by comparing the numerical results with the experimental ones. Example problems are included to investigate the characteristics of the coupled multi-domain system.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1086-1091
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• 2004

The boundary layer is a very important characteristic of a liquid-vapor interface since it governs the heat and mass transfer phenomena across an interface. However, the thickness of a boundary layer is generally micro- or nano-sized, which requires highly accurate measurement devices and, consequently, costs the related experiments very high and time-consuming. Due to these size dependent limitations, the experiments related with a nano-scaled size have suffered from the errors and the reliability of the obtained data. This study is performed to grasp the characteristics of a liquid-vapor interface, by using a molecular dynamics method. The simulation results were compared with other studies if possible. Although other studies reported that there existed a temperature discontinuity over an interface when the system was reduced to micro- or nano-sized, we confirmed that there was no such a temperature discontinuity.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.5
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• pp.393-398
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• 2001

This paper presents a new method with time-varying boundary layer and input gain, variated by Fuzzy Logic Control(FLC) by means of the system state in Sliding Mode Control (SMC). In addition to the time-varying boundary layer, the time-varying range of the fuzzy membership function has an effect on not only chattering reduction but also fast response characteristics. On the basis of SMC with time-varying boundary and FLC with time-varying input and output range, a computer simulation for inverted pendulum results in elimination of the chattering phenomenon and fast response.