• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1995.05a
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• pp.141-153
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• 1995

An incremental Total Lagrangian Formulation is implemented for the finite element analysis of laminated composite pressure vessel with consideration of the material and geometric nonlinearities. For large displacements/large rotations due to geometric nonlinearities, the incremental equations are derived using a quadratic approximation for the increment of the reference vectors in terms of the nodal rotation increments. This approach leads to a complete tangent stiffness matrix. For material nonlinearity, the analysis is performed by using the piecewise linear method, taking account of the nonlinear shear stress-strain relation. The results of numerical tests include the large deflection behavior of the selected composite shell problem. When compared with the previous analysis, tile results are in good agreement with them. As a practical example, filament wound pressure vessel is analyzed with consideration of the geometrically and materially nonlinearity. The numerical results agree fairly well with the existing experimental results.

• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.95-99
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• 2005

This paper presents the optimum design of cylindrical shell under external pressure loading. Two kinds of material, Al7075-T6, Ti-6Al-4V, are considered. For each material, the design variable is a thickness of the unstiffened parallel middle body shell, and the state variable, constraint, is hoop stress and the object .function is total weight of the cylindrical shell. Optimization is performed by conventional FE Program, ANSYS. In addition, buckling analysis is performed for the middle body of the cylindrical shell. Finally, we calculates the payload of the cylindrical shell to keep neutral buoyancy with optimized thickness in deep-sea applications.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.95-100
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• 2000

For the well-controlled growing in-situ heavily phosphorus doped polycrystalline Si films directly on Si wafer by reduced pressure chemical vapor deposition, a study is made of the two step growth. When in-situ heavily phosphorus doped Si films were deposited directly on Si (100) wafer, crystal structure in the film is not unique, that is, the single crystal to polycrystalline phase transition occurs at a certain thickness. However, the well-controlled polycrtstalline Si films deposited by two step growth grew directly on Si wafers. Moreover, the two step growth, which employs crystallization of grew directly on Si wafers. Moreover, the two step growth which employs crystallization of amorphous silicon layer grown at low temperature, reveals crucial advantages in manipulating polycrystal structures of in-situ phosphorous doped silicon.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.2
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• pp.163-169
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• 2000

In this paper, we showed the erosion characteristic of MgO protector layer releated to lifetime of plasma display panel(PDP). We observed MgO erosion characteristic as a functions of deposition conditions, pressure and distance between electrodes. In RIE condition of Xe gas, the lowest erosion rate appears in the conditions of no heating bias voltage -30V and pressure 5mtorr. In general, as deposition rate increases, erosion rate decreases. In real panel, when the gap distance between electrodes is narrow and the pressure is low, the heavy plasma damage appears. Also, the surfaces between electrodes and on the bus electrode are extremely damaged.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.451-454
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• 2001

The ionic conductivity of cubic solid solutions in the system Y$_2$O$_3$-ZrO$_2$ prepared by SHS was examined. Conductivity-temperature data obtained at 1000$^{\circ}C$ in atmosphere of low oxygen partial pressure (10$\^$-40/ atm) for Y$_2$O$_3$-ZrO$_2$ cubic solid solutions indicated that these materials could be reduced, the degree of reduction being related to the measuring electric field. At low impressed fields no reduction was observed. Thus, these conductivity data give a transference number for the oxygen ion in Y$_2$O$_3$-ZrO$_2$ cubic solid solutions greater than 0.99.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.121-125
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• 2001

We study the feasibility of synthesizing Si particles using PLA method. In the previous studies, it was possible to control the size of Si nanoparticles bythe He gas pressure. In this study, we fabricated sub-micron size Si particles with various shapes such as conical, hexagonal, and ring by controlling not only the ambient as pressure but also the laser energy density. Furthermore, we found that the conical Si particles were uniform-sized and had step shape when observed from FE-SEM and AFM. The conical Si particle has the same crystal structure as the bulk single crystalline Si by the analysis of the Raman scattering. It is shown that the relationship between the laser energy density and the He gas pressure inside the chamber affects the shape of the Si particle.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.287-290
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• 2000

We give pressure stimulation into organic thin films and then manufacture a device under the accumulation condition that the state surface pressure is 20[mN/m]. LB layers of Arac. acid deposited by LB method were deposited onto y-type silicon wafer as x, y, z-type film. In processing of a device manufacture, we can see the process is good from the change of a surface pressure for organic thin films and transfer ratio of area per molecule. The structure of manufactured device is Au/arachidic acid/Al, the number of accumulated layers. Also, we then examined of the MIM device by means of I-V. The I-V characteristic of the device is measured from 0 to +2[V].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.192-196
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• 2002

This paper describes on the fabrication and characteristics of a metal thin-film pressure sensor based on Cr strain-gauges for harsh environment applications. The Cr thin-film strain-gauges are sputter-deposited onto a micromachined Si diaphragms with buried cavity for overpressure protectors. The proposed device takes advantages of the good mechanical properties of single-crystalline Si as diaphragms fabricated by SDB and electrochemical etch-stop technology, and in order to extend the operating temperature range, it incorporates relatively the high resistance, stability and gauge factor of Cr thin-films. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097~1.21 $mV/V{\cdot}kgf/cm^2$ in the temperature range of $25{\sim}200^{\circ}C$ and the maximum non-linearity is 0.43 %FS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.185-187
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• 2004

The electron concentration of ZnO thin film fabricated by pulsed laser deposition was controlled by varying oxygen gas pressure. The electron concentration of ZnO was increased from $10^{17}\;to\;10^{19}/cm^3$ as oxygen gas pressure increased from 20 mTorr to 350 mTorr. Ultraviolet(UV) intensity of photoluminescence of ZnO was controlled, too. UV intensity of ZnO was increased as oxygen gas pressure increased from 20 mTorr to 350 mTorr. The relation between electron concentration and UV intensity was investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.325-326
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• 2006

In this study, in order to develop piezoelectric device for multilayer piezoelectric ultrasonic motor, low temperature sintering $Pb(Mn_{1/3}Nb_{2/3})_{0.02}(Ni_{1/3}Nb_{2/3})_{0.12}(Zr_{0.48}Ti_{0.52})_{0.86}O_3$ system ceramics were fabricated according to the variations of forming pressure of casting sheet. At the 300[$kgf/cm^2$] forming pressure, the maximum density of 7.8[$g/cm^3$] was obtained. At the 350[$kgf/cm^2$] forming pressure, the maximum values of effective electromechanical coupling factor $k_{cff}\;=\;0.24$ and mechanical quality factor Qm=628 were obtained.