• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.12-15
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• 1994

To establish the sea surface temperature estimation scheme for the upcoming advanced remote sensor, the quasi-analytical solution of the approximated radiative transfer equation which express the radiative transfer process of the radiant energy radiated from the sea surface to the satellite is approximated into the non-linear equation. To solve the simultaneous approximated radiative transfer equation which express the radiative transfer process of the radiant energy radiated from the sea surface to the satellite is approximated into the nonlinear equation. To solve the simultaneous approximated radiative transfer equation at each channel, the constrained non-linear optimization technique is adopted. To define the coefficients of the approximated radiative transfer equation and the constraints, the satellite detected radiance and the total transmittance are computed from the 1350 kinds of simulated atmosphere / surface models via radiative transfer code. The verification from the simulated data show the sufficient result.

• Journal of Power Electronics
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• v.5 no.2
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• pp.166-172
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• 2005

The basic equations of a doubly-fed long-stator linear motor for a shuttle-based railway system are established. They show which degrees of freedom exist for controlling the motor. The ratio of stator and rotor current proves to be an important parameter in determining the design of motors, converters and mechanics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.5
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• pp.407-413
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• 2005

Ion implantation provides a unique way to modify the mechanical, optical and electrical properties of polymer by depositing the energy of ions in the material on the atomic scale. Implantation of ions into the polymers generally leads to a radiation damage, which, in many cases, modifies the properties of the surface and bulk of the material. These modifications result from the changes of the chemical structure caused in their turn by changing the chemical bonding when the incident ions cut the polymer chains, breaks covalent bonds, promotes cross-linking, and liberates certain volatile species. We studied the relation among the linear energy transfer (LET) and changes of surface microstructure and surface resistivity on PPS material using the high current ion implantation technology The surface resistivity of nitrogen implanted PPS decreased to $10^{7}{\Omega}/cm^{2}$ due to the chain scission, cross linking, ${\pi}$ electron creation and mobility increase. In this case, the surface conductivity depend on the 1-dimensional hopping mechanism.

• Journal of Photoscience
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• v.9 no.3
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• pp.37-40
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• 2002

Astronauts are constantly exposed to space radiation at a low-dose rate during long-tenn stays in space. Therefore, it is important to determine correctly the biological effects of space radiation on human health. Space radiations contain various kinds of different energy particles, especially high linear energy transfer (LET) particles. Therefore, we have to study the relative biological effectiveness (RBE) of space radiation under microgravity environment which may change RBE from a stress for cells. Furthermore, the research about space radiation might give us useful information about birth and evolution of life on the earth. We also can realize the importance of preventing the ozone layer from depletion by use of exposure equipment to sunlight at International Space Station (ISS).

• Journal of Hydrogen and New Energy
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• v.23 no.2
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• pp.162-172
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• 2012

This paper presents a research about free piston linear engine (FPLE) fueled with hydrogen, in which, the numerical models are built to simulate the operation during the full stroke of the engine. Dynamic model, linear alternator model and thermodynamic model are used as the numerical models to predict piston velocity, in-cylinder pressure and electric power of FPLE. The spark timing and air gap length are changed to provide information for the prediction. Beside, the heat transfer problem is also investigated in the paper. The results of research are divided by two parts, including motoring mode and firing mode. The result of motoring mode showed that there is validation between simulation and experiment for volume and pressure in cylinder. For firing mode, by increasing spark timing, the velocity of piston, peak pressure and electric power also increase respectively. Beside, when increasing air gap length, the electric power increases accordingly while the motion of piston is not symmetric. The effect of heat transfer also observed clearly by reducing of the peak pressure, velocity of piston and electric power.

• Journal of Magnetics
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• v.18 no.2
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• pp.105-110
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• 2013

The design model and key parameters of the material design for the control of induced magnetic flux at the near-field and efficient power transfer in a modified wireless power transfer (WPT) system with a large air gap of wireless electric vehicles were investigated through analytical simulations for magnetic vector and time-domain transient analysis. Higher saturation magnetic core with low core loss induced a stronger vertical magnetic field by the W-type primary coil in the WPT system with a gap of 20 cm at 20 kHz, which is shown from the vector potentials of the magnetic induction. The transient analysis shows that the higher magnetic fluxes through the pick-up cores lead to a linear increment of the alternating voltage with a sinusoidal waveform in the non-contact energy transfer system.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.701-705
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• 1988

We have investigated imaging performance of digital rediography system by measured several imaging properties such as sensitivity characteristic, scatter fraction, modulation transfer function and detective quentum efficiency. The results show that digital rediography system has linear sesitivity to incident energy, excellent scatter elliminaility and high detective quentum efficiency, but poor modulatio transfer function.

• Nuclear Engineering and Technology
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• v.36 no.2
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• pp.153-164
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• 2004

A computational fluid dynamics (CFD) analysis has been performed to investigate the turbulent flow and heat transfer in a triangular rod bundle with pitch-to-diameter ratios (P/D) of 1.06 and 1.12. Anisotropic turbulence models predicted the turbulence-driven secondary flow in a triangular subchannel and the distributions of the time mean velocity and temperature, showing a significantly improved agreement with the measurements from the linear standard $k-{\epsilon}$ model. The anisotropic turbulence models predicted the turbulence structure for a rod bundle with a large P/D fairly well, but could not predict the very high turbulent intensity of the azimuthal velocity observed in the narrow flow region (gap) for a rod bundle with a small P/D.

• Journal of the Korean Chemical Society
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• v.43 no.2
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• pp.161-166
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• 1999

Transfer of lanthanide ions across the liquid/liquid interface facilitated by ionopore ETH4120 has been studied by using cyclic voltammetry (CV) and chronopotentiometry with cyclic linear current-scanning (CPCLCS) under the condition where the concentration of ETH4120 in nitrobenzene was much smaller than the concentration of lanthanide ions in aqueous solution. One cathodic current peak (transfer from aqueous to nitrobenzene phase) and two anodic current waves (transfer from nitrobenzene to aqueous phase) were observed. The cathodic wave was due to the formation of 1:1 (metal:ligand) complex and two anodic waves showed successive formation of 1:2 and 1:3 complexes in nitrobenzene solution. But there was no cathodic wave corresponding to two anodic waves. The ion transfer mechanism has also been discussed.

• Journal of Hydrogen and New Energy
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• v.25 no.2
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• pp.183-190
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• 2014

Our lab designs a heat exchangers for air and carbondioxide gas. Coolant is water, thus it is very difficult to determine heat transfer parameters in this gas-liquid system. Repeated experiments gives overdesign value 35%, overall heat transfer coefficient $33.8(kcal/m2-hr-^{\circ}C)$ for carbondioxide. Another series of experiments determine overdesign 18.7%, overall heat transfer coefficient $21.4(kcal/m2-hr-^{\circ}C)$ for Air. These parameters are in same range of literature. Overdesign is increasing as tube length increases, also increases as wall thickness of heat exchanger increases. To get proper fluid linear velocity in heat exchanger, we change the diameter of tube and finally we can have optimum fluid linear velocity in the heat exchanger.