• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.59-62
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• 1996

Plasma displays (PDP) as a large area wall-hanging display device are rabidly developed with flat CRT, TPT LCD and etc. Especially, AC Plasma Display Panels(AC PDPs) have the inherent memory function which is effective for large area displays. The memory function in AC PDPs is caused by the accumulation of the electrical charge on the protecting layer formed on the dielectric layer. This MgO protective layer prevents the dielectric layer from sputtering by ion in discharge plasma and also has the additional important roll in lowering the firing voltage due to the large secondary electron emission coefficient). Until now, the MgO Protective layer is mainly formed by E-Beam evaporation. With increasing the panel size, this process is difficult to attain cost reduction, and are not suitable for large quantity of production. To the contrary, the methode of shuttering are easy to apply on mass production and to enlarge the size of the panel and shows the superior adhesion and uniformity of thin film. In this study, we have prepared MgO protective layer on AC PDP Cell by reactive magnetron sputtering and studied the effect of MgO layer on the surface discharge characteristics of ac PDP.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.103-108
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• 2014

Using dried sludge as a secondary fuel of a coal-fired power plant is proposed as an alternative option for sludge disposal. Because elemental contents of sludge are different from those of coal, different levels of acidic gas emissions are expected from the co-combustion of sludge with coal. In this study, sludge samples were obtained from 7 sewage treatment plants in Korea. Each sludge sample was combusted together with coal in a lab-scale combustor, and the concentrations of nitrogen oxides ($NO_x$), sulfur dioxide ($SO_2$), hydrogen chloride (HCl), chlorine ($Cl_2$) in the flue gas were analyzed. Compared to the combustion of coal only, $NO_x$ concentration was slightly higher in the flue gas from the co-combustion of coal and sludge. $SO_2$ emission increased with the combustion of sludge due to the higher content of sulfur in sludge than in coal. For most of the tested samples, the concentrations of HCl and $Cl_2$ were varied depending on the chlorine content in the sludge sample.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.207-207
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• 2012

Si quantum dot (QD) imbedded in a $SiO_2$ matrix is a promising material for the next generation optoelectronic devices, such as solar cells and light emission diodes (LEDs). However, low conductivity of the Si quantum dot layer is a great hindrance for the performance of the Si QD-based optoelectronic devices. The effective doping of the Si QDs by semiconducting elements is one of the most important factors for the improvement of conductivity. High dielectric constant of the matrix material $SiO_2$ is an additional source of the low conductivity. Active doping of B was observed in nanometer silicon layers confined in $SiO_2$ layers by secondary ion mass spectrometry (SIMS) depth profiling analysis and confirmed by Hall effect measurements. The uniformly distributed boron atoms in the B-doped silicon layers of $[SiO_2(8nm)/B-doped\;Si(10nm)]_5$ films turned out to be segregated into the $Si/SiO_2$ interfaces and the Si bulk, forming a distinct bimodal distribution by annealing at high temperature. B atoms in the Si layers were found to preferentially substitute inactive three-fold Si atoms in the grain boundaries and then substitute the four-fold Si atoms to achieve electrically active doping. As a result, active doping of B is initiated at high doping concentrations above $1.1{\times}10^{20}atoms/cm^3$ and high active doping of $3{\times}10^{20}atoms/cm^3$ could be achieved. The active doping in ultra-thin Si layers were implemented to silicon quantum dots (QDs) to realize a Si QD solar cell. A high energy conversion efficiency of 13.4% was realized from a p-type Si QD solar cell with B concentration of $4{\times}1^{20}atoms/cm^3$. We will present the diffusion behaviors of the various dopants in silicon nanostructures and the performance of the Si quantum dot solar cell with the optimized structures.

• Journal of Power System Engineering
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• v.12 no.1
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• pp.13-19
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• 2008

In this study, a variable induction and exhaust system is applied to turbocharged diesel engine to improve the volumetric efficiency, especially, in a low and transient engine speed range where much of the pollutant matters are expelled out. The volumetric efficiency is known as one of the most important factor which affects significantly engine performance, fuel economy and further emission and noise level. As the torque increase with the engine speed up, the gas flow in an exhaust pipe become pulsating and then has an effect on boost up capacity of air charging into the cylinder and expelling capacity to atmosphere simultaneously. But at a low and idling speed, the pulsation effect was not so significant. Accordingly, resonator was employed to compensate their loss. The variable induction system consists of the secondary pipe, resonator, intercooler, and torque variance were examined with extended operating conditions. In the mean time, for interpretation and well understanding for the phenomena of wave action that arising during intake and exhaust process between turbocharger and variable intake system, the concept of the combined supercharging was introduced. Some of results are depicted which deal with a pressure history during valve events of induction process. Consequently, by the governing of these phase and amplitude of pulsating wave, it enables us to estimate and evaluate for the intake system performance and also, designing stage of the system layout.

• Korean Journal of Materials Research
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• v.18 no.8
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• pp.422-426
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• 2008

The effects of an addition of $ZrO_2$ on the microstructure and electrical properties of MgO films as a protective layer for AC plasma display panels were investigated. MgO + a 200 ppm $ZrO_2$ protective layer prepared by e-beam evaporation exhibited a secondary electron emission coefficient ($\gamma$) that was improved by 21% compared to that of a pure MgO protective layer. The relative density and Vickers hardness increased with a further addition of $ZrO_2$. These results suggest that the discharge properties and optical properties of MgO protective layers are closely related to the relative density and Vickers hardness. The good optical and electrical properties of $\gamma$, at 0.080, a grain size of $19\;{\mu}m$ and an optical transmittance of 91.93 % were obtained for the MgO + 200 ppm $ZrO_2$ protective layer sintered at $1700^{\circ}C$ for 5 hrs.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.351-355
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• 2014

Graphite electrodes are used for secondary batteries, fuel cells, and super capacitors. Research is underway to increased the reaction area of graphite electrodes used carbon nanotube (CNT) and porous carbon. CNT is limited to device utilization in order to used a metal catalyst by lack of surface area to improve. In contrast carbon nanowall (CNW) is chemically very stable. So this paper, microwave plasma enhanced chemical vapor deposition (PECVD) system was used to grow carbon nanowall (CNW) on Si substrate with methane ($CH_4$) and hydrogen ($H_2$) gases. To find the growth properties of CNW according to the reaction gas ratio, we have changed the methane to hydrogen gas ratios (4:1, 2:1, 1:2, and 1:4). The vertical and surficial conditions of the grown CNW according to the gas ratios were characterized by a field emission scanning electron microscopy (FE-SEM) and Raman spectroscopy measurements showed structure variations.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.202-203
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• 2006

In the AC PDP, the MgO film is used as electrode protective film. This film must provide excellent ion bombardment protection, high secondary electron emission, and should be high transparent to visible radiation. In this study, we investigated the relations between the crystal orientation and e-beam evaporation process parameters. The crystal orientation of the MgO layer depends on the conditions of deposition. The parameters are the thickness of the MgO film $1000{\AA}-6500{\AA}$, the deposition rate $200{\AA}/min{\sim}440{\AA}/min$, the temperature $150^{\circ}C{\sim}250^{\circ}C$, and the distance between crucible and substrate 11cm ${\sim}$ 14cm. The temperature of substrate and evaporation rate of source material, or deposition rate of the film, are definitely related to the crystal orientation of the MgO thin film. The crystal orientation can be changed by the distance between the target(MgO tablet) and the substrate. However, the crystal orientation is not much affected by the thickness of MgO thin film.

• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.319-327
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• 2007

Incineration has been regarded as the best developed technology available for organically hazardous waste. However, permitting and siting incinerators to treat hazardous waste such as a waste containing PCBs is very difficult due to the public concerns associated with toxic air emissions. Recently, a lot of alternatives to an incineration have been developed and these technologies have the potential of alleviating public concerns by decreasing emissions of hazardous materials such as dioxins and furans. This paper reviews currently available alternative incineration technologies for various hazardous waste streams. Various categories of non-thermal and thermal alternative incineration technologies have been evaluated in terms of their process operating condition, applicability of a waste stream and their emission of secondary waste. Detailed descriptions of operating principles of several technologies are also provided.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1368-1375
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• 2004

Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel do-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented fur typical locations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1033-1040
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• 2011

The premixed burner is a very strong candidate for using household boiler burner system because it has high efficiency, low emission and can be used in compact boiler system. Usually, household boiler burner systems use a Bunsen burner, which consists of an inner rich premixed flame and fuel burned completely by a secondary air supply. It has a relatively long flame length and operates in a high excess of air, so it is difficult to fit such a burner into a high efficiency compact boiler. In this paper, the characteristics of a premixed combustion burner for surface media such as metal fiber, ceramic, and SUS fin were evaluated. In particular, the flow velocity over the burner surface for the cold flow characteristics of the surface material were measured and adjusted. The combustion tests were carried out by taking pictures of the flame and measuring the flame temperature. The amounts of CO and NO were measured and the characteristics of the surface burner materials, combustion chamber, and heat exchangers were evaluated for various excess air ratios and heating values.