• Transactions on Electrical and Electronic Materials
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• v.15 no.1
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• pp.49-54
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• 2014

In this study, we carried out an investigation of the etch characteristics of silicon (Si) film, and the selectivity of Si to $SiO_2$ in $SF_6/O_2$ plasma. The etch rate of the Si film was decreased on adding $O_2$ gas, and the selectivity of Si to $SiO_2$ was increased, on adding $O_2$ gas to the $SF_6$ plasma. The optical condition of the Si film with this work was 1,350 nm/min, at a gas mixing ratio of $SF_6/O_2$ (=130:30 sccm). At the same time, the etch rate was measured as functions of the various etching parameters. The X-ray photoelectron spectroscopy analysis showed the efficient destruction of oxide bonds by ion bombardment, as well as the accumulation of high volatile reaction products on the etched surface. Field emission auger electron spectroscopy analysis was used to examine the efficiency of the ion-stimulated desorption of the reaction products.

• Transactions on Electrical and Electronic Materials
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• v.14 no.2
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• pp.67-70
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• 2013

In this study, we changed the input parameters (gas mixing ratio, RF power, DC bias voltage, and process pressure), and then monitored the effect on TiN etch rate and selectivity with $SiO_2$. When the RF power, DC-bias voltage, and process pressure were fixed at 700 W, - 150 V, and 15 mTorr, the etch rate of TiN increased with increasing $CF_4$ content from 0 to 20 % in $CF_4$/Ar plasma. The TiN etch rate reached maximum at 20% $CF_4$ addition. As RF power, DC bias voltage, and process pressure increased, all ranges of etch rates for TiN thin films showed increasing trends. The analysis of x-ray photoelectron spectroscopy (XPS) was carried out to investigate the chemical reactions between the surfaces of TiN and etch species. Based on experimental data, ion-assisted chemical etching was proposed as the main etch mechanism for TiN thin films in $CF_4$/Ar plasma.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.1 s.119
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• pp.1-7
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• 2007

Internal fibrillation of pulp fiber is an important factor affecting paper properties. Internal fibrillation of pulp fiber is usually introduced with several kinds of modifications of fiber by the mechanical treatment such as refining, high shear and/or high consistency mixing, etc. Unfortunately there are no standardized methods that can characterize the extent of internal fibrillation and its contribution on the paper properties. The purpose of this study is to try and find the potential methods that can characterize the internal fibrillation of pulp fiber quantitatively. Softwood bleached kraft pulp was treated with Hobart mixer to introduce the internal fibrillation without the significant fiber damage and external fibrillation. The extent of internal fibrillation was increased with the increase of mechanical treatment consistency. Several fiber properties were measured to find the potential means that could characterize and quantity the internal fibrillation. Laminated area could not be used as a means for quantifying the internal fibrillation because of the effect of swelling and the different internal fibrillation behavior at different mechanical treatment consistency. Micro and macro internal fibrillation models were proposed for describing the different behavior for the mechanical treatment at low and high consistencies of pulp. The Internal fibrillation showed good correlation with swelling of fiber wall. This trend was confirmed through the measurement of wall thickness and/or cross section area of fiber. Therefore the internal fibrillation possibly can be described as the indices indicating the change of wall thickness and/or cross section area.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.276-282
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• 2004

Barley flakes were developed by extrusion cooking using broken kernels, by-products of the barley pearling process. Broken kernels from both non-waxy and waxy barley broken kernels were sufficiently gelatinized at the barrel temperature of over $100^{\circ}C$ and the moisture content of broken kernels of over 35%. Cutting and flaking roll separating properties of pellets prepared from non-waxy barley broken kernels were better than those of waxy barley broken kernels. Characteristics of pellets prepared by extrusion cooking in different mixing ratios of non-waxy and waxy barley broken kernels were investigated. As the mixing ratio of waxy barley broken kernels increased, RVA peak viscosity, apparent viscosity, and yield stress of prepared pellets decreased, while flow behavior index increased. As the mixing ratio of waxy barley broken kernels increased, compressive strength and bulk density of deep-fat fried flakes drastically decreased, and the size of air cells on cross-section increased, and thickness of cell-constituting bodies decreased. Sensory evaluation results showed that acceptability for texture and taste of flakes inclosed as the mixing ratio of waxy barley broken kernels increased, and optimum mixing level of waxy barley broken kernels appeared to be 30-40%.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.901-906
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• 1998

Gas and liquid flow characteristics were investigated in an internal circulation airlift reactor using a single nozzle for a gas distributor. In three reactors with different diameters of the downcomer and heights of the riser, the gas holdup in the individual flow zone and the impulseresponse curve of tracer for an air-water system were measured for various gas velocities and reactor heights. Experimental results showed that the flow behavior of bubbles in the riser was the slug flow due to strong coalescences of bubbles and that the bubble flow pattern in the downcomer was the transition bubble flow for the smaller diameter of the downcomer, however, it was the homogeneous bubble flow for the larger one. And mean gas holdups in the individual flow zone and the reactor were greatly increased with decreasing the diameter of the downcomer for the equal ratio of height of the top section to that of the riser. Also, the mixing time was much effected by the height of the top section of reactor and for the equal ratio of height of top section to that of the riser, it was increased with increasing the diameter of the downcomer and the height of the riser. Flow characteristics of liquid were mainly varied with the bubble flow pattern in the downcomer and the size of the top section of reactor. And circulation velocities of liquid in the riser were increased with increasing gas velocities and the size of the top section of reactor, and for the equal ratio of height of top section to that of the riser, they were increased with increasing the diameter of the downcomer and the height of the riser.

• Journal of Mushroom
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• v.12 no.4
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• pp.275-279
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• 2014

Pleurotus pulmonarius usually grows on the dead wood of deciduous trees from mid summer to early fall. Cultivation of this mushroom is recently increasing due to its good flavour and fragrance. This study was conducted to find out the favorable substrate formulation in the bottle and bag cultivation of P. pulmonarius. The V formulation (10 : 50 : 20 : 20 mixing ratio of poplar sawdust, cottonseed hull, cottonseed meal and beet pulp) showed the fastest mycelial growth in the test tube column medium and highest yields in both bottle cultivation and bag cultivation. Those chemical conditions were pH 5.52, 29.07% organic matter contents, 1.12% total nitrogen, 25.95 OM/N ratio, 0.16% CaO, 0.51% $K_2O$, 0.17 MgO and 0.26 $P_2O_5$.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.657-660
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• 2008

In this study, quantitative analysis on effect of hydration heat and autogenous shrinkage of concrete using BFS was studied. Especially, it analyze section data statistically which hydration heat and autogenous shrinkage rise, and it appeared the correlation of hydration heat and autogenous shrinkage as well as quantitative coefficients of the main properties. As a result, the section which hydration heat and autogenous shrinkage of BFS-50 rise rapidly is delayed than OPC, but the slope of hydration heat and autogenous shrinkage in that section appeared similar shape in each mixing. Finally it will be possible to control the amount of autogenous shrinkage because hydration heating velocity and autogenous shrinking velocity are decreased by using BFS.

• Journal of Mechanical Science and Technology
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• v.14 no.9
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• pp.1005-1012
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• 2000

Numerical optimization techniques combined with a three-dimensional thin-layer Navier-Stokes solver are presented to find an optimum shape of a stator blade in an axial compressor through calculations of single stage rotor-stator flow. Governing differential equations are discretized using an explicit finite difference method and solved by a multi-stage Runge-Kutta scheme. Baldwin-Lomax model is chosen to describe turbulence. A spatially-varying time-step and an implicit residual smoothing are used to accelerate convergence. A steady mixing approach is used to pass information between stator and rotor blades. For numerical optimization, searching direction is found by the steepest decent and conjugate direction methods, and the golden section method is used to determine optimum moving distance along the searching direction. The object of present optimization is to maximize efficiency. An optimum stacking line is found to design a custom-tailored 3-dimensional blade for maximum efficiency with the other parameters fixed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.5 no.3
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• pp.159-169
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• 1981

The mixing length theory is extended to close the momentum queations for two-phase turbulent flow at a first-order closure level. It is assumed that the mass fraction of the particles is of the order of unity, that the particle size is so small that the particles are fully suspended is the primary fluid, and that the relaxation time scale of the particles is of the same order as the time scale of the energy containing eddies so that the suspended particles are responsive to the fluctuating turbulent field. The bulk motion of the particles is treated as a secondary fluid with its own coefficient of momentum transport. The proposed closure is uniformly destributed acress the pipe section. Predicted velocity profiles and the friction factors are in good agreement with avaiable experimental data.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.3
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• pp.63-70
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• 1990

In a premixed flame stabilized by a streamlined step, the flame structure and combustion characteristics were investigated to identify the effect of the pressure pulsation in a combustion air. A flame stabilizing limits, visualization, mean temperature, ion current and gas concentration (O$_{2}$, CO$_{2}$, CO, UHC) were measured. With the combustion air of higher pressure pulsation, the development of the mixing layer was fast and wide, the temperature and combustion intensity were higher at arbitrary section. But, the effect was notably decreased with X=150 mm downstream. And a first eddy formation from step edge was earlier. Thus, with the combustion air of higher pressure pulsation, high rate of heat generation was expected.