• Journal of Power System Engineering
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• v.4 no.1
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• pp.39-44
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• 2000

The purpose of this study is to investigate the flame structure and combustion characteristics in the model gas turbine combustor changing equivalence ratio. For this purpose, temperature and ion current were measured and these data were analyzed by the PDF and power spectra technique. We found that the flame length is longer while increasing the equivalence ratio in experimental condition, and especially ${\psi}=0.19$, combustion reaction was active by the stable swirl flow. and these flames were governed by the random three dimensional eddy.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1609-1611
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• 1994

In ECR and helicon reactors for plasma processing, a high density plasma is generated in a source region which is connected to a diffusion region where the processing takes place. Large density and potential gradients can develop at the orifice of the source which drive ion currents into the diffusion region. The average ion velocity may become the order of the sound velocity. Measurements of the ion saturation current to a Langmuir probe are used as a standard method of determining the plasma density in laboratory discharges. However, the analysis becomes difficult in a steaming plasma. We have used the HAMLET plasma simulator to simulate the ion flow to a large langmuir probe in an ECR plasma. The collection surface was aligned with the Held upstream, normal to the field, and downstream. ion trajectories through the electric and magnetic fields were calculated including ion-neutral collisions. We examines the ratio of ion current density to plasma density as a function of magnetic field and pressure.

• Journal of Surface Science and Engineering
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• v.30 no.3
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• pp.159-166
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• 1997

The metalliding technique was adopted to obtain the diffusion coating of zirconium on AISI 304 Stainless Steel in molten mixed chlorides (32.9wt.%LICl-34.8wt.%NaCl-32.3wt.%). Experiments were carried out in argon gas atmosphere. The electrolytic cell was consisted of a AISI 304 Stainless steel cathode and a consumable zirconium anode. The quality of deposit was analysed by SEM, Optical Microscope, EDS, and also examined by the Micro-Vickers hardness and corrosion tests. Interface of deposit layer was identified as zirconium-iron alloy layer caused by diffusion process at elevated temperatures. The optimum condition for the metalliding was found to be the bath temperature of $550^{\circ}C$, the concentration of $K_2ZrF_6$ ,5wt.%, cathodic current derrent density of 7.0 to 10.0mA/$\textrm{cm}^2$ , and anodic current density of 2.0mA/$\textrm{cm}^2$.

• Journal of Hydrogen and New Energy
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• v.14 no.3
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• pp.195-206
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• 2003

Polymer electrolyte membrane fuel cells(PEMFC) are very interesting power source due to high power density, simple construction and operation at low temperature. But they have problems such as high cost, improvement of performance and effect of temperature. This problems can be approached using mathematical models which are useful tools for analysis and optimization of fuel cell performance and for heat and water management, in this paper, transient model consists of various energy terms associated with fuel cell operation using the mass and energy balance equation. And water transfer in the membrane is composed of back diffusion and electro-osmotic drag. The temperature calculated by transient model approximately agreed with the temperature measured by experiment in constant current condition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.44-48
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• 1999

In order to the investigate for the DC(forward-reverse) breakdown properties of gate oxide in MOSFET, we are manufactured the specimen as following. The resistivity is 1.2($\Omega$ $.$ cm), 1.5($\Omega$ $.$ cm) and 1.8($\Omega$ $.$ cm) when thickness is 600(${\AA}$), and the diffusion time is both 110[min] and 150[min] when thickness is 600[${\AA}$]. In DC dielectric strength due to the each resistivity, it is confirmed that almost of the leakage current and breakdown current is flowed through n+ source when positive bias is applied, but is flowed through P region when negative bias is applied. It is thought that the dielectric strength due to the diffusion time is the contribution as increasing of p region.

• Bulletin of the Korean Chemical Society
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• v.15 no.3
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• pp.209-213
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• 1994

Two unknown values among three electrochemical values, i.e. electrode area, diffusion coefficient, and concentration, are simultaneously obtained by nonlinear regression analysis of a single chronoamperometric faradaic current curve at a microdisk electrode. The approach is an analytical application of the semi-empirical equation presented by Shoup and Szabo for the chronoamperometric response at a disk electrode. To demonstrate the usefulness and accuracy of this approach, the chronoamperometric current at a platinum disk electrode of 50 ${\mu}m$ radius in solutions of $Ru(NH_3)_6^{3+},\;ferrocene,\;Fe(CN)_6^{3-},\;and\;C_{60}$, were analyzed.

• Journal of Magnetics
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• v.15 no.4
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• pp.149-154
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• 2010

Synthetic antiferromagnets (SAFs) are used as free layer structures for various magnetic devices utilizing spintransfer torque (STT). Therefore, it is important to understand current-induced excitation of SAFs. By means of drift-diffusion and macrospin models, we studied the current-induced excitation of a SAF-free layer structure (NiFe/Ru/NiFe). The simulation results were compared with the previous experimental results [N. Smith et al., Phys. Rev. Lett. 101, 247205 (2008)]. We confirmed that a nonzero STT through the Ru layer is essential for explaining the experimental results.

• Proceedings of the KSMRM Conference
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• 2007.10a
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• pp.68-68
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• 2007

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.05a
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• pp.119-119
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• 1996

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.4
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• pp.261-270
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• 1992

To investigate the flow patterns and diffusions in the Taean coastal waters of the eastern Yellow Sea, hydraulic and numerical experiments of tidal currents and diffusions of dye and cooling water were performed during spring tide along with field observations. Flow patterns obtained by the hydraulic and numerical experiments approximately coincide with those of the field observations. In the fold observations of tidal current, currents flow southwestward during the ebb tide, while currents flow northeastward during the flood tide. and the maximum velocity is 2.13 ㎧ toward WSW direction. The Eulerian diffusion coefficient estimated from field measmements of current is 7.82$\times$10$^{5}$ $\textrm{cm}^2$/s. Diffusion coefficients obtained from the area of dye plume in the model are given by the expression 0.18 $r^{4}$3/, and the coefficients have the range of 10$^{5}$ ~10$^{6}$ $\textrm{cm}^2$/s. These values are similar to the Eulerian diffusion coefficient estimated fram field measurements. Diffusion coefficients obtained in the hydraulic model are one to two orders higher than those obtained in the Onsan Bay in the eastern waters and two to three orders higher than those obtained in the Chinhae Bay in the southern waters of the Korean Peninsula. Diffusion patterns of cooling water by numerical experiments are similar to those of dye plume by hydraulic experiments. Both hydraulic and numerical experiment results of diffusions of dye plume and cooling water in the Taean coastal waters, have shown that the diffusion during the ebb tide is more prevalent than one during the flood tide.