• Journal of ILASS-Korea
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• v.19 no.4
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• pp.221-226
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• 2014

This paper described the effect of split injections on the stability of combustion and emission characteristics in a direct injection gasoline engine at various operating conditions. In order to investigate the influence of direct injection gasoline engine, the fuel injection timing was varied direct fuel injection at various fuel pressure. The experimental apparatus consisted of GDI engine with 4 cylinder, EC dynamometer, injection control system, and exhaust emissions analyzer. The emission and combustion characteristics were analyzed for the fuel injection timing and fuel injection pressure strategies. It is revealed that CO and HC emissions are dramatically decreased at advanced injection timing. Also, engine performance is increased at increase fuel injection pressure.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1107-1112
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• 2008

The objective of this paper is to investigate into the influence of the injection conditions on the insert deformation and the wall thickness of the injection part using the three-dimensional injection molding analysis. Full three-dimensional insert model was added to the injection molding analysis model to consider the effects of insert deformation during the injection molding process. In order to obtain the optimum injection molding condition with a minimum insert deformation, degree of experiments were utilized. From the results of the analyses, it was shown that the optimum injection condition is injection time of 1.6 sec, injection pressure of 30 MPa and packing time of 15 sec. In addition it was shown that the wall thickness is approached to target thickness when the core deformation is considered in the injection molding analysis.

• Journal of ILASS-Korea
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• v.18 no.1
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• pp.61-65
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• 2013

In case of GDI engine, shape of injected fuel and injection mass are one of the most important factors for good fuel efficiency and power. But it should be too inefficient and difficult to acquire injection mass data by experiment because condition in engine vary with temperature, pressure, and so on. So, this paper suggests the AMESim (Advanced Modeling Environment for Simulation of Engineering Systems) as simulation program to calculate injection mass. For both simulation and experiment, n-heptane is used as fuel. In AMESim, I modeled the GDI injector and simulated several cases. In experiment, I acquired the injection mass using Bosch method to apply ambient pressure. The AMESim show reasonable result in comparison with experimental data especially at injection pressure 15 MPa. Other conditions are also in good accord with experimental data but error is a little bit large because the injection mass is so low.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.302-305
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• 2007

In recent years, many researches on new storage media with high capacity and information are developing. For manufacture of optical storage with high capacity, the injection molding process is generally used. In order to increase the filling ratio of the injection molding structure, the injection molding process required for high injection pressure, packing pressure and temperature control of the mold. However, conventional injection molding process is difficult to increase the filling ratio using injection master with the range of several nanometers and high aspect ratio. In order to improve and increase filling ratio of nano-structure with high aspect ratio, the active temperature control of injection mold was used. Experimental conditions were used injection pressure, time and temperature. Consequently, by using the peltier device into injection mold, we carried out the efficient and active temperature control of mold at low cost.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.9-15
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• 2004

The characteristics of combustion and emissions were investigated in a single cylinder DI diesel engine equipped with a common rail injection system. This study presents an experimental study of the effect of engine speed, injection timing, injection pressure and pilot injection timing on the combustion and exhaust emissions. The engine speeds were 1000 and 2000rpm and the corresponding injection pressures were 50 and 100MPa. Experimental results show that NOx emissions decrease with retarded injection timing, while HC and CO emissions increases. Higher injection pressure increases NOx with lower soot emissions. For the case with the pilot injection prior to main injection, the ignition delay is shortened and the premixed combustion ratio decreases. Also NOx and soot emissions are decreased with increase of pilot injection advance.

• The Korean Journal of Pain
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• v.32 no.1
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• pp.39-46
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• 2019

Background: Lumbosacral transforaminal epidural injection (TFEI) is an effective treatment for spinal disease. However, TFEI may have several types of complications, some of which can be attributed to intravascular injection. We reviewed studies to compare the intravascular injection rate among different needle types. Methods: We searched the literature for articles on the intravascular injection rate among different needle types used in TFEI. The search was performed using PubMed, MEDLINE, the Cochrane Library, EMBASE, and Web of Science. Results: A total of six studies comprising 2359 patients were identified. Compared with the Quincke needle, the Whitacre needle reduced the intravascular injection rate (OR = 0.57, 95% CI = [0.44-0.73], P < 0.001). However, compared with the Quincke needle, the Chiba needle did not reduce the intravascular injection rate (OR = 0.80, 95% CI = [0.44-1.45], P = 0.46). In one study, the intravascular injection rate using a blunt-tip needle was lower than that using a sharp needle. In another study, the Whitacre and the blunt-tip needle have similar intravascular injection rates, while, the catheter-extension needle showed a reduced intravascular injection rate. Conclusions: This meta-analysis showed that the Whitacre needle reduced the intravascular injection rate as compared with the Quincke needle, but failed to establish that the Chiba needle can decrease the intravascular injection rate in TFEI. Moreover, the blunt-tip needle can reduce the intravascular injection rate compared with the Quincke needle, and the catheter-extension needle can reduce the intravascular injection rate compared with the Whitacre and the blunt-tip needle.

• Elastomers and Composites
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• v.52 no.4
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• pp.317-325
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• 2017

Molding conditions can be described as factors that determine the quality of a product obtained from injection molding. Many studies have been performed on the injection molding pressure, injection temperature, packing pressure and other molding conditions related to part quality. However, the most accessible factor among the adjustable molding conditions during actual injection is the injection speed. In this study, we simulated the variation of the physical quantity according to injection speed and performed experiments to understand the effect of injection speed on the actual product. A CAE analysis program (Moldflow) was used to simulate and analyze the results using PC and PBT for two models. In order to compare these results with the experimental results, an actual injection molding was performed for each injection speed, and the correlation between simulation and injection molding, especially for the shrinkage of the molded article, was discussed.

• International Journal of Automotive Technology
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• v.6 no.4
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• pp.315-322
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• 2005

This work was performed to investigate the effect of a split injection on spray characteristics of fuel sprays injected from a common rail system. In order to analyze the spray behavior and atomization characteristics at various rates of split injections, the injection durations of pilot and main injections were varied in experiments. The injection rate of split injection was measured to study the effect of the pilot injection on the main injection. By using a Nd:YAG laser and an ICCD camera, the development of the injected spray was visualized at various elapsed time from the start of injection. The microscopic characteristics such as SMD and axial velocity were analyzed by using a phase Doppler particle analyzer system. The results indicate that the ambient gas flow generated by the pilot injection affects the behavior of main spray, whereas the effect of pressure variation on the main spray is little. The spray tip penetration of a main spray with pilot injection is longer than that of the single injection by the effect of ambient gas flow. Also the main spray produces larger droplets than the pilot spray due to a small relative velocity between the droplets and ambient gas.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.5
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• pp.82-92
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• 1996

A computer simulation with predict the fuel injection rates and the fuel injection pressure behaviors in diesel engine fuel injection systems would by very useful in designing or improving fuel injection systems. In this paper we developed computer program in order to predict the behaviors of the fuel injection rate and the injection pressure for Electronic Hydraulic Ultra-High Pressure Fuel Injection System. We've applied the continuity and momentum equations for the hydraulic phenomena and the dynamics of individual components of the Electronic Hydraulic Fuel Injection System. To solve all the equations numerically we've applied the Runge-kutta IV method. Water hammer equations were applied for the hydraulic pipe solution, and the method of characteristics was employed in our calculations. The simulation results were compared with the experimental results for: Accumulator pressure, Injection pressure and unjection rate. As a result, The simulation results agree very well with our experimental results. We found that a large accumulator and the high speed solenoid valve were required, and the compression volume of the fuel had to be as small as possible in order to acheive ultra-high pressure fuel injection.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.55-64
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• 2014

This work was investigated on pilot injection strategy of blended fuels(Diesel-DME) for combustion and emissions in a single cylinder direct injection compression ignition engine. Diesel and DME were blended by the method of weight ratio. Weight ratios for diesel and DME were 95:05 and 90:10 respectively. dSOI between main and pilot injection timing was varied. A total amount of injected fuels(single injection) was adjusted to obtain the fixed BMEP as 4.2 bar in order to compare with the fuel conditions. Also, the amount of pilot injection fuel was varied by 5%, 10% and 20% of total injection fuel. The engine was equipped with common rail and injection pressure is 700 bar at 1200 rpm. As a result, when mixing ratio increase, indicated thermal efficiency was increased in comparison with DD 100 and CO, THC and smoke were lower than DD 100. The influence of reducing NOx by pilot injection was more effective than DD 100. When pilot injection quantity increase, abrupt increase of NOx was occured at pilot injection quantity of 20%.