• Clean Technology
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• v.18 no.4
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• pp.410-418
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• 2012

The performance of the ammonia injection gun (AIG) used for maximizing the utilization of reducing agent in the selective catalytic reduction (SCR) system is decided by several parameters such as the pattern of flow distribution, geometry of the air distribution manifold (ADM) and the array and geometry of nozzles. In the study, the uniformity of jet flows from the nozzles in AIG was analyzed statistically by using the computational fluid dynamics (CFD) method to evaluate the role of design parameters on the performance of the SCR system. The uniformity of jet flows from the nozzles is being deteriorated with increasing the supplying flow rate to the AIG. Distribution rates to each branch pipe become lower with decreasing distance to the header, and flow rates from nozzle are also reduced with decreasing distance to the header. The uniformity of jet flows from nozzles becomes stable significantly when the ratio of summative area of nozzles to each sectional area of the branch pipe is below 0.5.

• Design & Manufacturing
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• v.18 no.2
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• pp.41-50
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• 2024

In this study, experimental design methods were used to derive optimal process conditions for improving the thickness uniformity of a 0.40 mm, 3.5 inch light guide panel. Process mapping and expert group analysis were used to identify factors that influence the thickness of injection molded products. The key factors identified were mold temperature, mold temperature, injection speed, packing pressure, packing time, clamp force, and flash time. Considering the resin manufacturer's recommended process conditions and the process conditions for similar light guide plates, a three-level range was selected for the identified influencing factors. L27 orthogonal array process conditions were generated using the Taguchi method. Injection molding was performed using these L27 orthogonal array to mold the 3.5 inch light guide plates. Thickness measurements were then taken, and the results were analyzed using the signal-to-noise ratio to maximize the CpK value, leading to the determination of the optimal process conditions. The thickness uniformity of the product was analyzed by applying the derived optimum process conditions. The results showed a 97.5% improvement in the Cpk value of 3.22 compared to the process conditions used for similar light guide plates.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.11
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• pp.1140-1147
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• 2009

Flow analyses have been performed to investigate the uniformity of propellant flow through the fuel and oxidizer manifolds of a full-scaled gas generator for a pump-fed liquid rocket engines. Injectors were simulated as porous medium layers having equivalent pressure drops. The uniformity of propellants has been analyzed for 3 fuel rings and 3 injector head configurations. The mixture ratio distribution at the exit of injectors has been estimated from the mass flow rates of fuel and oxidizer. The best configuration of fuel ring and injection head was selected through these flow analyses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.216-219
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• 2005

In recent, LCD becomes one of the main display devices and expected to have quite good market share during the next couple of years. The demand for low cost and high performance, however, is becoming severe as the competition among other display devices like PDP, OLED increases. To satisfy this demand from market, we need to optimize the parts or modules of the LCD, reduce the number of the assemble and enhance the process for the high brightness and uniformity of the LCD. The LCD consists mainly of LCD panel and Backlight unit(BLU). BLU, which takes big portion of the cost for LCD, consists of light source, light guide panel and many kinds of functional film. Recently light guide panel or film for BLU has micro patterns on its surface and consequently to reduce the number of parts and enhace the brightness and its uniformity. In this study, some methodologies for the fabrication of the master/stamper and molding the light quide panel are introduced for 50um pitch of prizm patterned substrate. Mechanical machining process is adapted and optimized to fabricate micro patterned stamper using the micro cutting tool. Injection molding technology is also developed to obtain uniformly replicated micro patterned products.

• Design & Manufacturing
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• v.1 no.1
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• pp.27-32
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• 2007

In the optical application demand for high quality lens is increasing. Plastics lenses are demanded more than glass lenses for large size lenses as well as micro-size lenses. It is difficult to apply typical straight cooling channels of injection mold to lens molding due to its non-uniform temperature distribution. In this study, we manufactured molds for plastic lenses with the conventional cooling channels and conformal cooling channels produced by the DMLS process. We evaluated cooling performance for the 2 molds by injection molding experiment. Also, uniformity of the temperature distribution was tested by infrared camera and temperature monitoring. We confirmed that the cooling performance and temperature uniformity with the conformal cooling channels is much improved from the ones with the conventional. The cooling time with the conformal cooling channels was reduced 30% compared with the conventional cooling channels.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.16 no.1
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• pp.89-102
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• 1987

Experiments have been carried out to study the atomisation characteristics of superheated liquid(water) jet injected into the atmosphere through a single-hole nozzle. In present experi-mental range, superheated liquid jet has been observed to be atomised in two-phase effluent type; that is, spray formed by the bubble nucleation in the nozzle. In case of liquid injection through a long nozzle (L/D=29.09), the critical superheat for occurrence of two-phase effluent atomisa-tion can be determined from sudden change of spray angle. Sauter mean diameter of the spray droplets decreases as the degree of superheat increases. For the short nozzle (L/D=7.27), mean diameter increases with the injection pressure, while it decreases for the long nozzle; however for the long nozzle the effect of injection pressure is not significant compared with the short nozzle. For the short nozzle the uniformity of drop size distribution increases with increasing the degree of superheat, but for the long nozzle the effect of superheat on the uniformity is not appreciable.

• Design & Manufacturing
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• v.9 no.3
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• pp.24-28
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• 2015

Speaking in general terms the form injection process can be described as a new process-variant of already known structural foam molding technology which roots go back to the early sixties. The most limiting factors of already know foaming processes are large cell size and the lack of uniformity of these cells as well and the inability to foam all kinds of plastic materials. In this paper, Process Study on weight change in injection rate during foaming. Experimental conditions were set as the injection speed 50,150,300 and 450 mm/s. The experiments PA, PA+GF, PP, was confirmed that the weight increase to PP+TA.

• Transactions of Materials Processing
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• v.16 no.1 s.91
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• pp.54-60
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• 2007

Optimum injection molding condition for a box mold was searched by the Response Surface Analysis(RSA) with the aid of process monitoring system(PMS). Process variables on the control panel of the injection molding machine such as barrel temperatures, screw speed profile, holding pressures, etc. cannot guarantee the uniformity of the material variables directly related with the state of the product in the mold cavity. In order to make sure the state of the resin in the cavity, pressures and temperatures in the cavity, runner and nozzle were monitored in the experiment with the PMS. To accomplish the consistency of the molding process, dependent variables such as the switchover point and holding time were searched with the PMS. With a proper objective function about deflection of the box-type product, the optimum injection molding condition was obtained.

• Design & Manufacturing
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• v.13 no.4
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• pp.34-39
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• 2019

In this paper, in order to improve the formability and quality of the injection molded parts in the molds for molding the motorcycle rear cowl injection molded parts with different volumes at the same time, the flow of the molded parts is changed through the injection molding CAE analysis by changing the gate position, runner size and position. It is to find the optimum gate position, the diameter of the runner and the position where the balance is equal. The molded article formed by the optimization resulted in the uniformity of the molten resin at the same time at the corner of the product, thereby maintaining the flow balance favorable for mass production at lower injection pressure.

• Journal of the Semiconductor & Display Technology
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• v.5 no.2 s.15
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• pp.41-46
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• 2006

Wet etching process in recent semiconductor manufacturing is devided into batch and single wafer type. Batch type wet etching process provides more throughput with poor etching uniformity compared to single wafer type process. Single wafer process achieves better etching uniformity by boom-swing injected chemical on rotating wafer. In this study, etching characteristics of $SiO_2$ layer at room and elevated temperature is evaluated and compared. The difference in etching rate and uniformity of each condition is identified, and the temperature profile of injected chemical is theoretically calculated and compared to that of experimental result. Better etching uniformity is observed with single wafer tool with boom-swing injection compared to single wafer process without boom-swing or batch type tool.