• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1332-1336
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• 2005

It could make the LIghtweight Piezoelectric Composite Actuator (LIPCA) damageable by the cyclic large deformation. If the progressive microvoid coalescence of LIPCA interlaminar took place, the decrease of the stiffness and the weakness of stress transmission and fiber bridging effect would make the fatigue characteristics worse suddenly. Therefore, it is required to study the variation of fatigue behavior and interlaminar condition in LIPCA under resonant frequencies. These studies such as the changeable fatigue phase and interlaminar behavior of LIPCA affected by the resonant frequencies should be carried out due to the strong anisotropy of CFRP layer. Hence, these studies are as follows. 1) The residual stresses distribution of interlaminar in LIPCA using the Classical Lamination Theory (CLT). 2) Comparative analysis of interlaminar behavior for the intact LIPCA versus LIPCA containing an artificial delamination during resonant frequency.

• Journal of Korean Academy of Nursing Administration
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• v.9 no.3
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• pp.481-494
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• 2003

Purpose: This study was to develop nursing competencies, sub-competencies and behavior indicators according to the clinical ladder of emergency nurses. Method: index of content validation was used by 21 clinical experts. Results: This study had three phases to develop nursing competencies, sub-competencies and behavior indicators. In first phase: 12 nursing competencies and 33 sub-competencies were developed through the literature review on nursing competency and emergency nurses' job description. The content of 12 competencies and 33 sub-competencies were reviewed by 3 nursing professors. The 12 competencies and 33 sub-competencies were followed: clinical judgement and measures(6 sub-competencies), processing ability of ward works(2 sub-competencies), flexibility(2 sub-competencies), resources management(2 sub-competencies), confidence(3 sub-competencies), cooperation(2 sub-competencies), professional development power(2 sub-competencies), patient service orientation(3 sub-competencies), inclination toward ethical value(5 sub-competencies), influence power(2 sub-competencies), developing others(2 sub-competencies), self control(2 sub-competencies). In second phase, 132 behavior indicators were developed according to nurse clinical ladder: novice, advanced novice, competent, proficient. In Third phase, content validity was examined on 132 behavior indicators by 21 clinical experts. 126 among 132 indicators had over 70% agreement among experts and 6 indicators under 70% were revised. Conclusion: nursing competencies, sub competencies and behavior indicators can be used nurses' clinical performance as well as establishing proper directions for professional growth related to reward system.

• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.44-50
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• 1990

The liquid chromatographic retention behavior of structural isomers of phenols was investigated by a change of the mobile phase properties. The retention behavior of structural isomer of phenols in reversed phase liquid chromatography was affected by eluent electrolyte added. It can be seen that this behavior is illustrated by a mechanism of Langmuir isotherm and ion exchange between phenolate and the reversed phase coated with ions. The retention behavior was represented as two different areas according to the concentration of the electrolytes. These areas can be explained as counter ion and co-ion effect, respectively. The maximum retention values were dependent not upon the kinds of organic modifier but upon the kinds of electrolyte.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.149-157
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• 2000

Computer simulations of the mechanical behavior of a three point bend specimen with a quarter notch under impact load are performed. The case with a load application point at the side is considered. An elastic-plastic von Mises material model is chosen. Three phases such as impact bouncing and bending phases are found to be identified during the period from the moment of impact to the estimated time for crack initiation. It is clearly shown that no plastic deformation near the crack tip is appeared at the impact phase. However it is confirmed that the plastic zone near the crack tip emerges in the second phase and the plastic hinge has been formed in the third phase. Gap opening displacement crack tip opening displacement and strain rate are compared with rate dependent material(visco-plastic material). The stability during various dynamic load can be seen by using the simulation of this study.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.206-212
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• 2016

Experimental data are reported on the phase equilibrium of propoxylated neopentyl glycol diacrylate in supercritical carbon dioxide. Phase equilibria data were measured in static method at a temperature of (313.2, 333.2, 353.2, 373.2 and 393.2) K and at pressures up to 27.82 MPa. At a constant pressure, the solubility of propoxylated neopentyl glycol diacrylate for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system increases as temperature increases. The (carbon dioxide + propoxylated neopentyl glycol diacrylate) system exhibits type-I phase behavior. The experimental result for the (carbon dioxide + propoxylated neopentyl glycol diacrylate) system is correlated with Peng-Robinson equation of state using mixing rule. The critical property of propoxylated neopentyl glycol diacrylate is predicted with Joback and Lyderson method.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.372-377
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• 2009

We report on hysteresis behavior in the electrical resistance-hydrogen concentration of Pd thin films. The variation of the electrical resistance has been investigated during the process of absorption and desorption of hydrogen gas ($H_{2}$) as a function of thickness of Pd thin films. The hysteresis behavior in the electrical resistance with $H_{2}$ concentration was found for Pd thin films and consists of $\alpha$ phase, ${\alpha}+{\beta}$ phase, and $\beta$ phase regions. The sensitivity of Pd thin films with $H_{2}$ concentration was found to follow Sieverts' law in the $\alpha$ phase region. However, the sensitivity was observed to increase abruptly with $H_{2}$ concentration in the ${\alpha}+{\beta}$ phase co-exist region. This is because Pd-H interaction is stronger in the $\beta$ phase than in the $\alpha$ phase and needs a higher concentration gradient as a driving force to desorb. The formation of the $\beta$ phase also was observed to cause the structural change because of the lattice expansion during absorption. The hysteresis height and the trace of structural change were affected by the thickness of the Pd film. As the film becomes thinner, the hysteresis height becomes lower and the amount of delamination on the surface becomes smaller. For films thinner than 20 nm in thickness, the delamination was not found but electrical resistance hysteresis was still observed.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.777-783
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• 1994

Oxidation behavior of hot-pressed silicon nitride ceramics with various sintering additives has been investigated. The weight gain of each specimens has shown in the range of 0.11 mg/$\textrm{cm}^2$ ~3.4 mg/$\textrm{cm}^2$ at 140$0^{\circ}C$ for 192 h and eleven compositions have shown good oxidation resistance with the weight gain below 0.5 mg/$\textrm{cm}^2$. The oxidation rate has been shown to obey the parabolic rate law and the oxidized surface has consisted of $\alpha$-cristobalite and M2Si2O7 or MSiO3 (M=rare earth or transition metals) phase. The oxidation rate of each specimens has related to the eutectic temperature between additive oxide and SiO2, and ionic radius of additive oxides, respectively. From the above results, it could be concluded that the oxidation behavior of hot pressed silicon nitride is dominated by the high temperature properties of grain boundary glassy phase and the high temperature properties of grain boundary glassy phase are affected by the ionic radius of additive oxides.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.894-899
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• 2004

In this paper, the track pull-in behavior analyses in an optical disk drive (ODD) using plane phase is treated and the parameters affecting it are discussed. Track pull-in is the track capture procedure to do track following control and it is key factor to increase data transfer rate. Simulation method, Runge-Kutta method to solve nonlinear equation, is used to evaluate the track pull-in conditions, and the real servo loop parameters are applied in this process to get the more real condition. Finally, the comments for the acquired results are discussed briefly.

• Journal of Communications and Networks
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• v.6 no.3
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• pp.197-202
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• 2004

This work presents a stability analysis of the synchronous state for one-way master-slave time distribution networks with single star topology. Using bifurcation theory, the dynamical behavior of second-order phase-locked loops employed to extract the synchronous state in each node is analyzed in function of the constitutive parameters. Two usual inputs, the step and the ramp phase perturbations, are supposed to appear in the master node and, in each case, the existence and the stability of the synchronous state are studied. For parameter combinations resulting in non-hyperbolic synchronous states the linear approximation does not provide any information, even about the local behavior of the system. In this case, the center manifold theorem permits the construction of an equivalent vector field representing the asymptotic behavior of the original system in a local neighborhood of these points. Thus, the local stability can be determined.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.1
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• pp.19-27
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• 1988

The mechanical properties of Ferrite-Martensite dual phase steels are affected by microstructural factors, such as, martensite volume fractions, grain size of ferrite, hardness ratio of Ferrite-Martensite, connectivity and chemical components etc. Therefore, this study has been made on the influence of Impact fracture behavior which changes the hardness ratio of Ferrite-Martensite by mean of heat treatment of low carbon Mn-Steels. In order to analyze and examine the effect of fracture behavior under impact load, this study investigated the impact strength, the impact loading time, the absorbed energy on the fracture ductility of Ferrite-Martensite dual phase steels, the formation of micro crack and slip, and plastic restraint of martensite on the plastic deformation.