• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.925-928
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• 1998

In this paper, the electron transport characteristics in $SiH_4$ has been analysed over the E/N range $0.5{\sim}300[Td]$ and Pressure value 0.5, 1, 2.5 [Torr] by a two-term approximation Boltzmann equation method and by a Monte Carlo simulation. The motion has been calculated to give swarm parameters for the electron drift velocity. diffusion coefficient, electron ionization, mean energy and the electron energy distribution function. The electron energy distribution function has been analysed in $SiH_4$ at E/N=30, 50[Td] for a case of the equilibrium region in the mean electron energy and respective set of electron collision cross sections. The results of Boltzmann equation and Monte carlo simulation have been compared with experimental data by Pollock, Ohmori, cottrell and Walker.

• Transactions of Materials Processing
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• v.10 no.6
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• pp.449-456
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• 2001

The concept of stress wave was introduced through the quantized kinetic energy which is related to the potentional energy change of atom, molecular bond energy. Differentiated molecular bond energy $\varphi$() by the lst order displacement u becomes force F(F = d$\varphi$($u_i$)/du), if resversely stated, causing physically atomic displacement $u_i$. Such physical phenomena lead stress(force/area of applied force) can be expressed by wave equation of linearly quantized physical property. Through the stress wave concept, formation of dislocation, which could not explained easily from a theory of continuum mechanics, can be explained. Moreover, this linearly quantized stress wave equation with a stress concept for grains in a crystalline solid was applied to three typical metallic microstructures and a simple shape. The result appears to be a product from well treated equations of a quantized stress wave. From this result, it can be expected to answer the reason why the defect free and very fine diameters of long crystalline shapes exhibit ideal tensile strength of materials.

• Proceedings of the KIEE Conference
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• 2004.07e
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• pp.37-40
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• 2004

Electron swarm parameters in pure $CF_4$ and mixtures of $CF_4$ and Ar, have been analyzed over a range of the reduced electric field strength between 0.1 and 350[Td] by the two-term approximation of the Boltzmann equation(BEq.) method and the Monte Carlo simulation(MCS) The results of the Boltzmann equation and the Monte Carlo simulation have been compared with the data presented by several workers. The deduced transport coefficients for electrons agree reasonably well with the experimental and simulation data obtained by Nakamura and Hayashi. The energy distribution function of electrons in $CF_4$-Ar mixtures shows the Maxwellian distribution for energy. That is, f(${\varepsilon}$) has the symmetrical shape whose axis of symmetry is a most probably energy

• Journal of the Korean Electrochemical Society
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• v.9 no.4
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• pp.151-157
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• 2006

A two-dimensional numerical model to study the performance of anode-supported flat-tube solid oxide fuel cell (SOFC) far the cross section of the cell in the flow direction of the fuel and air flows is developed. In this model a mass and charge balance, Maxwell-Stefan equation as well as the momentum equation by using, Darcy's law are applied in differential form. The finite element method using FEMLAB commercial software is used for meshing, discritization and solving the system of coupled differential equations. The current density distribution and fuel consumption as well as water production are analyzed. Experimental data is used to verify a predicted voltage-current density and power density versus current density to judge on the model accuracy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.5
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• pp.360-371
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• 2003

The calculation of each unit cost of productions is very important for evaluating the economical efficiency and deciding the reasonable sale price. In the present, two methods of exergy costing on multiple energy systems are suggested to reduce the complexities of conventional SPECO method and MOPSA method and to improve the calculation efficiency of exergoeconomics. The suggested methods were applied to a gas-turbine cogeneration and the unit costs of the power and the steam energy were calculated as an example. The main points of our methods are the following three. First, one exergetic cost is applied to one cycle or system. Second, the suggested equations are the internal cost balance equation and the production cost balance equation. Third, necessary states in a system are only inlet and exit states of 1ha components producing energy.

• Proceedings of the KIEE Conference
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• 2005.10a
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• pp.97-100
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• 2005

This paper describes the electron transport characteristics in SiH4 has been analysed over the E/N range 0.5${\sim}$300[Td] and Pressure value 0.5, 1, 2.5 [Torr] by a two-term approximation Boltzmann equation method and by a Monte Carlo simulation. The motion has been calculated to give swarm parameters for the electron drift velocity, diffusion coefficient, electron ionization, mean energy and the electron energy distribution function. The electron energy distribution function has been analysed in $SiH_4$ at E/N=30, 50[Td] for a case of the equilibrium region in the mean electron energy and respective set of electron collision cross sections. The results of Boltzmann equation and Monte carlo simulation have been compared with experimental data by Pollock, Ohmori, cottrell and Walker.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.692-696
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• 1993

Prediction of retention times in transition metal-mandelate and transition metal-tartrate complex systems were studied on the cation exchanger. Plots of k' vs [mandelate] and k' vs [tartrate] were obtained under the condition of a constant competing cation concentration. The equation to predict the retention time of transition metal ion was derived from the ion exchange equilibria. Individual capacity factors (${k_1}',\;{k_2}'$) and stability constants ($K_1,\;K_2$) of the complexes were calculated from the non-linear least square method. Good resolution of the transition metals was predicted by the stepwise equation in the gradient method. The values of retention times from the calculation and the experiment agreed well each other.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11b
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• pp.571-576
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• 1996

The 3-stage cascade composed of the multisection-type bithermal $H_2$/$H_2O$-exchange columns was suggested for heavy water separation. In order to study the separation characteristics for the cascade, a matrix equation with 18 simultaneous equations was composed and the concentrations and flow rates were calculated for the all parts of the cascade. Product D-concentration decreases and extraction yield increases with increasing cut in each stage, which is one of the principal parameters of the separation characteristics. The optimization of the 3-stage cascade can be made by case study using the matrix equation.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.20-25
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• 1989

The nonlinear, time dependent photon transport equations of Frantz and Nodvik, which describe the amplification of an optical pulse in an active medium, are modified to a simpler equation which describes only the amplification of energy. with this equation, the output energy of the high power YLF(Nd3+)-Phosphate Glass(Nd3+) Laser System is calculated. When the stored energy density Est is 0.10J/㎤, 0.16J/㎤, 0.228J/㎤, and 0.50J/㎤, and with the assumption of uniform population inversion density, the final output energy of this laser system is 5.38J, 176J, 317J, and 283J, respectively. The gain saturation causes distortion of the output beam. This phenomenon is described in detail at the first three rod amplifier systems in the case of E=0.228J/㎤. The peak current and decay time constant of the flashlamps, which are used to obtain population inversion in the active medium, are investigated. The flashlamp driving circuit which has optimum operational performance should have {{{{ SQRT { LC} }} time about 100$\mu$sec.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.131-136
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• 2018

Research on space development and satellites is being actively pursued. An interesting field is the study of reliable low-cost space launch vehicles. Since chemical fuel-based launching systems are expensive and take a lot of time and cost to maintain, the EML system, which is an electromagnetic force launching apparatus, is attracting attention. The EML system converts electrical energy stored in a capacitor into magnetic energy, and converts magnetic energy into mechanical kinetic energy, thereby accelerating the projectile. Although studies are actively conducted in the field, it is difficult to solve the equation because the impedance and speedance change with time and the nonlinearity is strong. Many researchers have solved this equation in a variety of methods. In this paper, the velocity analysis of the projectile was carried out by FEM (finite element method) using the commercial electromagnetic analysis program MAXWELL.