• Polymer(Korea)
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• v.33 no.6
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• pp.561-568
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• 2009

Small injection molded articles are generally molded by multi-cavity injection molding. The most important thing in multi-cavity molding is flow imbalance among the cavities because it affects the physical property and the quality of products. The cavity filling balance can be achieved by flow balance in the runner through the thermal balance. In this study, novel screw type runner or helical type runner has been developed for the flow balance in the runner and performed experiment and computer simulation. Flow balance has been observed using various screw type runners for several resins such as amorphous and crystalline polymers including low and high viscosities grades. Flow balance experiments have been performed for various injection speeds since the flow balance can be affected by injection speed among the injection conditions. Experimental results have been compared with computational results and they showed good agreement. The cavity filling balance can be achieved by the screw runner where the temperature distribution is uniform through the circulation flow along the screw channel in the screw runner. It has been verified that the novel screw runner is very effective device in flow balance in the multi-cavity injection molding. cavity filling imbalance, multi-cavity injection molding, runner design, screw runner, thermal balance.

• Korean Journal of Optics and Photonics
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• v.16 no.2
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• pp.168-173
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• 2005

Ag-doped $TiO_2$ thin films were prepared by RF magnetron co-sputtering method, and their physical and chemical properties were examined as a function of calcination temperature. XRD results showed that the crystallite size of Ag-doped films was smaller than that of the $TiO_2$ thin films. SEM results showed that the particle size of $Ag/TiO_2$ film was smaller and more uniform than pure $TiO_2$ film. The films had high transparency in the visible range. The films calcined at $600^{\circ}C$ were the anatase phase, and the films calcined at $900^{\circ}C$ were a mixture of anatase and rutile phases. The absorption edge of films calcined at $900^{\circ}C$ was red-shifted. This is due to the augmented absorption resulting from the phase transformation from anatase to rutile phase. And the transmittance of films decreased by the light scattering and absorption in the films. Photocatalytic activity of $Ag/TiO_2$ thin films was higher than that of the pure $TiO_2$ thin films.

• Plant Journal
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• v.13 no.2
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• pp.46-51
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• 2017

In this study, the boiler efficiency and the change of boiler combustion state with the burner operation of the uppermost layer of 870MW opposite fired coal boiler were measured. Test results showed that the boiler efficiency was high in the order of the uppermost layer simultaneous operation of the front and rear burners, the front burner, and the rear burner operation. When the front and rear burners were operated simultaneously, the heat absorption rate of water walls in the boiler furnace was uniform at four side, and the temperature deviation of the left and right steam on the convection front surface decreased. As the heat absorption rate of the boiler improved, the loss of boiler exhaust gas decreased and the coal supply amount decreased by 8 tons/hour compared to the operation of the rear burner. This will contribute not only to the reduction of fuel cost but also to the reduction of greenhouse gas emissions.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.295-300
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• 2000

Uniform silicon tip arrays were fabricated using the reactive ion etching followed by the reoxidation sharpening, and the effect of Pd-coated layer on electron emission characteristics was studied. The electron emission from Si field emitter arrays(FEAs) was a little, but improved by removing surface oxide on the FEA, but pronounced drastically by coating a $100-{\AA}-thick$ Pd metal layer. The turn-on voltage in the Pd-coated Si FEAs was reduced by 30 V in comparison with that in uncoated ones. This results from the increase of surface roughness at the tip apex by the Pd coating on Si FEA, via the decrease of the apex radius at which electrons are emitting. The Pd-coated emitters showed superior operating stability over a wide current range to that of the uncoated ones. This suggests that Pd coating enhances the high temperature stability and the surface inertness Si FEA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.496-502
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• 2007

In this paper, a slotted waveguide feeder for the electric field uniformity in multi-mode cavity is designed and fabricated. In case of the conventional feeder, a mode stirrer or a turntable is used for improving electric field uniformity in the multi-mode cavity. The proposed feeder has four slots, which have uniform radiation characteristic, on broad wall and shorted terminations at both ends. The electric field uniformity is simulated by CST's MWS(Microwave Studio) for the conventional and proposed feeders, respectively. The fabricated feeder shows the return loss of less than -20 dB at 2.45 GHz. To verify the validity of our proposal, the temperature distribution of the water samples in the multi- mode cavity is observed after a few minutes' heating. The proposed feeder is confirmed to have much better field uniformity in the multi-mode cavity than the conventional feeder.

• Resources Recycling
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• v.18 no.1
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• pp.22-29
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• 2009

To design and construct a moving bed stoker incinerator for incineration treatment of the domestic oil fly ash, operating condition and moving bed area of incinerator were determined by performing incinerate experiment of the oil fly ash in the muffle furnace which simulates moving bed stoker incinerator in all conditions. Incineration process of the oil fly ash could be divided into 3 stages, every stage needs the appropriate operating condition for effective incineration. The optimum content of water in the heavy oil fly ash was found to be 20 wt% to prevent the ash from flying and reduce the volume. Science combustion rate of oil fly ash depends on the oxygen content, the incinerator must have a equipment to control the oxygen content in the combustion air. The optimum temperature was $750{\sim}800^{\circ}C$ in order to prevent adhesion to the stocker and evaporation of metal compounds of low melting point. Uniform combustion reaction and acceleration of combustion rate required agitation during the combustion of oil fly ash. The incineration rate was $12.53kg/m^2hr$ and the working area of moving bed incinerator was found to be $60m^2$ to incinerate 18 tons of oil fly ash per day.

• Weed & Turfgrass Science
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• v.1 no.4
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• pp.64-68
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• 2012

Creeping bentgrass (Agrostis stolonifera L.) is one of the highest maintained turfgrass but often problematic especially for Kentucky bluegrass fairway. Mesotrione is one of selective herbicide that is firstly registered for corn (Zea mays L.) and provides preemergence and postemergence control of broadleaf and annual grassy weeds. Although mesotrione is effective to eradicate area contaminated by creeping bentgrass, protracted time is required to recover damaged area by rhizome extension of Kentucky bluegrass. Overseeding is typically used to fill bare or damaged areas using appropriate turf species to create a uniform turfgrass surface. The objectives of this study were to evaluate mesotrione and seeding rate effects to recover Kentucky bluegrass contaminated by creeping bentgrass. Six treatments consisted of three mesotrione rates and two Kentucky bluegrass seeding rates. The mesotrione rate were 0, 0.05 and 0.10 m $ml^{-2}$. Two seeding rate of to Kentucky bluegrass 'Midnight' were 15 and 30 g $m^{-2}$. Mesotrione application and Kentucky bluegrass overseeding at the same time is helpful to damage creeping bentgrass but not for establishment of Kentucky bluegrass to refill damaged area. To maximize mesotrione effects, temperature above $20^{\circ}C$ would be recommended based on this study.

• Korean Journal of Materials Research
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• v.6 no.8
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• pp.779-785
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• 1996

Thin $700^{\circ}C$films were formed through layer inversion of Co/Nb bilayer during rapid thermal annealing(RTA). The Nb interlayer seems to effectively prevent over-consumption of Si and to control the silicidation reaction by forming Co-Nb intermetallic compounds and removing the native oxide formed on Si substrate which interferes the uniform Co-Si interaction. The final layer structure of the Co/Nb bilayer after $700^{\circ}C$ RTA was found to be ${Nb}_{2}{O}_{3}$/${Co}_{2}$Si.CoSi/${NbCo}_{x}$/Nb(O, C)/${CoSi}_{2}$/ Si. The layer inversion and the formation of a stable CoSi, phase occurred above $700^{\circ}C$, and the Nb silicides were not found at any annealing temperature. These may be due to the formation of very stable Co-Nb intermetallic compounds and Nb oxides which limit the moving of Co and Si.

• Current Research on Agriculture and Life Sciences
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• v.31 no.3
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• pp.193-199
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• 2013

This study dyed rayon fabric using loess as a natural colorant. To obtain the optimal dyeing conditions, various dyeing conditions were examined (temperature, pH, time, and concentration). The color fastness was evaluated using standard washing and rubbing fastness tests. The results were as follows: The loess powder particle size ranged from 0.4 to $1.7{\mu}m$ with a distribution range of 1.1 to $1.4{\mu}m$, representing a fine and uniform manufactured loess powder. The loess component analysis showed a large amount of silicon dioxide and aluminum oxide. TheFT-IR spectra showed that the ammonium group in the rayon fabric produced N-H banding at $1,540cm^{-1}$. The highest K/S value for the rayon fabric was obtained when the pH was 8.0, and this value increased rapidly with a longer dyeing time and when increasing the loess concentration to 30% (w/v). Pre-treatment with a soybean solution produced the highest K/S value for the rayon fabric with a loess concentration of 30% (w/v). The SEM analysis showed a higher amount of loess adhered to the rayon fabric surface when increasing the loess concentration. However, pre-treatment with a cationic agent and soybean solution resulted in a much higher attachment of loess to the fabric surface. Thus, the experimental results showed that using a cationized fabric and pre-treatment with a soybean solution are more effective when dyeing rayon fabric with loess than when using only loess.

• Polymer(Korea)
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• v.38 no.2
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• pp.193-198
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• 2014

Lens and DVD require high quality of optical property. Conventional injection molded products contain high residual stress and this invokes birefringence since high cavity pressure and high temperature variation are involved in a molding process. Thus these products are often molded by injection compression molding in order to minimize the residual stress through reducing cavity pressure and uniform cavity pressure. In this study, molding parameters affecting molding quality such as property uniformity in injection compression molding were investigated through experiment. Molding quality deviations among the cavities in multi-cavity mold were also studied. Transparent resins, PC and PS were used in this study. Compression gap, compression speed, compression force, and compression delay time for processing variables in injection compression molding were applied in experiment. Compression force, compression delay time, and compression gap significantly affected the optical property of product. The degree of influence of process variable on the product quality was different in different resins. This implies that the optimal operational conditions in injection compression molding existed for each resin according to flow property.