• Journal of the Korean Society of Safety
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• v.24 no.1
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• pp.14-20
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• 2009

Direct numerical simulations(DNS) were performed for the prediction of transient buoyant jet diffusion flames where the Froude numbers(Fr) are 5 and 160, respectively. The thermodynamic and transport properties were evaluated using CHEMKIN package to enhance the prediction performance of the DNS code. The simulated buoyant jet diffusion flame of Fr=5 and 160 showed the transient, dynamic motion well. It was identified that the buoyant jet flames were flickered periodically, and the simulated flickering frequency of the jet diffusion flame of Fr=5 was 12.5Hz, which was in good agreement with the experimental results. The flamelet structures of the buoyant jet diffusion flames could be well understood by comparing the scalar dissipation rates(SDR) and the heat release rates(HRR) of the flames. It was found that the SDR was strongly coupled with the HRR in the buoyant jet diffusion flames.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.203-209
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• 2018

To correctly predict the neutron behavior based on diffusion calculations, it is necessary to adopt well-specified boundary conditions using suitable diffusion approximations to transport boundary conditions. Boundary conditions such as the zero net-current, the Marshak, the Mark, the zero scalar flux, and the Albedo condition have been used extensively in diffusion theory to approximate the reflective and vacuum conditions in transport theory. In this paper, we derive and analyze these conditions to prove their mathematical validity and to understand their physical implications, as well as their relationships with one another. To show the validity of these diffusion boundary conditions, we solve a sample problem. The results show that solutions of the diffusion equation with these well-formulated boundary conditions are very close to the solution of the transport equation with transport boundary conditions.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.04a
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• pp.6-7
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• 1999

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.142.1-142.1
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• 2016

We present bulk diffusion rates of hydroxide ions in amorphous solid water (ASW) at 135 ~ 160 K. Previous researches showed that the diffusion mechanism of hydroxide is different from one of hydronium ions, and this implies that they have different diffusion rates. In ultra-high vacuum (UHV) chamber, low-energy scattering (LES) was used to measure ion population and temperature-programmed desorption (TPD) was conducted for measuring ASW thicknesses. To determine the diffusion rates, a simple model for $H_2O/NaOH/H_2O$ sandwich films was developed using Fick's second law. The measured surface population of hydroxide ions as a function of time was well fitted to the model, and the rates were well agreed to an Arrhenius equation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1127-1134
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• 1994

The analytical model for the induced Hall field in the magnetotransistor considering the diffusion of carriers has been proposed and verified by experiment and simulation. Previous models for the induced Hall field in the magnetotransistor do not consider the influence of the diffusion carrier transport. However, the carrier diffusion in the base region of magnetotransistors cannot be neglected and should be considered to evaluated the Hall field in the magnetotransistors accurately. We have measured the Hall voltage in the base region of the fabricated magnetotransistors. The measured values have been compared with the numerical results evaluated from our diffusion model as well as the calculated results from the conventional model. The evaluated Hall voltage from the diffusion model agrees well with the measured values while the sign of the Hall voltage calculated by the conventional model is opposite to that of the measured values in the saturation region. This discrepancy is due to the fact that the diffusion model considers the carrier diffusion while the conventional one does not. The Hall field model including the influence of carrier diffusion may be an important tool to optimize the device structure and to understand the operating principle of the magnetotransistor.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.131-139
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• 1996

Inthis apper wa analyzed the channel-hot-electron programming characteristics of the single-poly EEPROM with different control gate and drain structures. The single-poly EEPROM uses the p$^{+}$/n$^{+}$-diffusion in the n-well as a control gate instead of the second poly-silicon. The program and erase characteristics of the single-poly EEPROM were verified using the two-dimensional device simulator, MEDICI. The single-poly EEPROM was fabricated using 0.8$\mu$m ASIC CMOS process, and its CHE programming characteristics were measured using HP4155 parameteric analyzer and HP8110 pulse gnerator. Especially we investigated the CHE programming characteristics of the single-poly EEPROM with the p$^{+}$-diffusion or n$^{+}$-diffusion in the n-well as a control gate and the LDD or single-drain structure. The single-poly EEPROM with p$^{+}$-diffusion in the n-well as a control gate and single-drain structure was programmed to about VT$\thickapprox$5V with VDS=6V, VCG=12V(1ms pulse width).th).

• Korean Journal of Microbiology
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• v.28 no.3
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• pp.278-282
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• 1990

Diffusion and partition of progesterone into the polyacrylamide gel was examined. Diffusion coefficient of progesterone decreased down to an asymptotic value as the concentration of the organic solvents in the diffusing medium increased. However the partition coefficient diminished steadily. Crosslinking density in the gel didn't affected the diffusion coefficient considerably but lowered the partition coefficient due to the contraction of pore volume of the gel. Progesterone showed higher diffusion coefficient as well as partition coefficient in the polyurethane than in the polyacrylamide gel, which seems to be ascribed to the difference in hydrophobicity, pore volume and pore size of the polymer matrix.

• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.8
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• pp.959-965
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• 1988

Zinc diffusion characteristics and its applicabilities have been studied using an open-tube system. Thermal decomposition of arsenide(As) at gallium arsenide(GaAs) wafer surface was well inhibited by using Ga: poly-GaAs: Zn compositon as a diffusion source. Junction depth was obtained as 4.6x10**7\ulcorner exp)-1.25/kT) where activation energy of diffusion was 1.25eV. From Boltzmann-matano analysis, it could be identified that concentration dependencies of Zn diffusivity well consisted with those of kick-out model. The ideality factor of p+-n junction formed by Zn diffusion was about 1.6 and infrared light intensity was linearly varied in the range of sixty folds. It is concluded frodm these results that Zn diffuses according to kick-out model, and open-tube method is applicable to compound semiconductor devices.

• Journal of applied mathematics & informatics
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• v.31 no.1_2
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• pp.241-246
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• 2013

Choi [1] identified and characterized the limiting diffusion of this diploid model by defining discrete generator for the rescaled Markov chain. In this note, we define the operator of projection $S_t$ on limiting diffusion and new measure $dQ=S_tdP$. We show the martingale property on this operator and measure. Also we conclude that the martingale problem for diffusion operator of projection is well-posed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.108-115
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• 2018

Time is considered as an important factor to understand the diffusion behavior of single generation technology. However, multiple generation technology required additional factors in addition to time to understand the diffusion behavior. This study defined the diffusion path of multiple generation technology based on dimensions of 'time, price, and performance' after extracting price and technical performance factors and traced the diffusion path of semiconductor industry based on defined dimensions. The case study of semiconductor industry indicated that the diffusion path is determined maximizing the integrated area of price and performance. This study has theoretical implications in that it analyzed the diffusion behavior of multiple generation technology based on multiple dimensions and can forecast the diffusion behavior at matured as well as early stage technology. Also, this study has practical implications for R&D and marketing managers to understand time-to-market, exit time, and economical as well as technical requirements.