• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.107-114
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• 2009

A Common-Rail Direct Injection (CRDI) system for high speed diesel engines was developed to meet reductions of noise and vibration, emission regulations. High pressure in the common rail with electric control allows the fuel quantity and injection timing to be optimized and controlled throughout a wide range of engine velocity and load conditions. In this study, CRDI system analysis model which includes fuel and mechanical systems was developed using commercial software, AMESim in order to predict characteristics for various fuel injection components. The parameter sensitivity analysis such as throttle size, injection rate, plunger displacement, supply pressure of fuel injection for system design are carried out.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.149-153
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• 2008

The cavity of mold is exposed to high pressure during injection molding operation. Injection molded articles with deep depth are often demanded as design variety increases. Mold becomes weak and deformation increases as the mold depth increases. Thus the injection molds for deep depth articles should be designed to hold out high pressure or stress and large deformation. Through this study, equation for mold design was examined and suggested novel method to determine equation for mold design with deep depth. Novel equation developed in this study was consisted with cantilever and two points bending while previous equation was modified from just cantilever bending. The validity of novel equation was verified through computer simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.445-448
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• 2005

Recently, injection molding process became more popular than ever to produce large quantities of high precision products or optical products. Injection molding products can cause sensorial problems because of high birefringence or deformation from the residual stresses in the optical media. In the present study, we have focussed on the effect of holding and compression pressures on the optical anisotropy remaining in the MOD by examining the gapwise distribution of birefringence and extinction angle The effect of holding pressure was found to form the inner two birefringence peaks. But the effect of compression pressure on the birefringence distribution was found to make the uniform distribution near the center in the gap-wise direction. Finally, the value of the birefringence near the wall decreased as the mold temperature increased.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.301-304
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• 2008

The cavity of mold is exposed to high pressure during injection molding operation. Injection molded articles with deep depth are often demanded as design variety increases. Mold becomes weak and deformation increases as the mold depth increases. Thus the injection molds for deep depth articles should be designed to hold out high pressure or stress and large deformation. Through this study, equation for mold design was examined and suggested novel method to determine equation for mold design with deep depth. Novel equation developed in this study was consisted with cantilever and two points bending while previous equation was modified from just cantilever bending. The validity of novel equation was verified through computer simulation.

• Journal of ILASS-Korea
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• v.16 no.1
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• pp.44-50
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• 2011

An object of this study is to understand the correlation of injection characteristics and injector dimensions according to biodiesel mixture. The Injection characteristics of different types of common-rail injectors are the number of nozzle holes (5~8), jet cone angle ($146^{\circ}{\sim}153^{\circ}$), hydraulic flow rate (830~900 ml/min) injection quantity and response time. Prior to characteristic experiment, the reference injector has been selected in 6 candidates injectors under the investigation of injected quantity according to the biodiesel mixture so that injector type can be determined. The injector is used for the characteristic experiment which varied the various operating conditions including pressure 23 MPa, 80 MPa, 160 MPa, changing in injection duration 0.16 ms~1.2 ms and even mixture ratio. The result shows that the nozzle hole number and cone angle influence the injection quantity much more than nozzle hole diameter at low injection pressure and the nozzle hole diameter at high injection pressure, post injection duration.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.1
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• pp.48-53
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• 2000

The effects of the internal flow in a diesel injection nozzle on the atomization of the spray has been investigated experimentally. Flow visualization was made using a transparent acrylic model nozzle. And also, measurement of the sac chamber pressure was made for clartfying the effect of pressure fluctuation in the sac chamber on the wpray behaviors. The geometry of the model nozzle was scaled up 10 times of the actual nozzle and the injection pressure for the model nozzle was adjusted so as to achieve a Reynolds number at the discharge hole which was the same as the actual nozzle. Polystyrene tracers, a laser sheet light and a still/high speed video camera were used to visualize the flow pattern in the sac chamber. When the needle lift was small, the high turbulence in the sac chamber generated by the high velocity seat flow made the spread angle of the spray large. Cavitation which arose in the sky chamber induced the pressure fluctuation and then affects the spread angle of the spray.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.911-917
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• 2015

The objective of this work focuses on the analysis of injection rate and macroscopic spray behavior characteristics with injection pressures as well as combustion and exhaust emission characteristics with injection timing and injection pressure by using a common rail single-cylinder diesel engine. The injection rate was measured by applying the Bosch method, and macroscopic spray behavior characteristics were analyzed with a constant-volume vessel and a high-speed camera. In addition, combustion and emission characteristics were analyzed in a common-rail single-cylinder diesel engine with precise control of fuel injection timing and pressure. For injection pressures of 30MPa and 50MPa, the injection rate was higher at 50 MPa, and the spray development (penetration) was also higher in the same elapsed time. The peak in-cylinder pressure and rate of heat release showed a tendency to decline as injection timing was delayed, and the peak in-cylinder pressure and rate of heat release were slightly higher for higher injection pressures. Higher injection pressures also reduced the mean effective pressure, while the indicated mean effective pressure and torque increased as injection timing was delayed to TDC. Nitrogen oxides had a peak level at injection timings of $BTDC20^{\circ}$(30MPa) and $BTDC15^{\circ}$(50MPa); carbon monoxide emissions were reduced by delaying injection timing from $BTDC30^{\circ}$.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.5
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• pp.73-80
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• 2002

Dimethyl ether (DM) is one of the most attractive alternative fuel far compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-holes sac type injector (hole diameter 0.168 ㎜/hole) was performed in a high pressure chamber pressurized with nitrogen gas. A CCD camera was employed to capture time series of spray images followed by spray cone angles and penetrations of DME were characterized and compared with those of diesel. Under atmospheric pressure condition, regardless of injection pressure, spray cone angles of the DME were wider than those of diesel and penetrations were shorter due to flash boiling effect. Tip of the DME spray was farmed in mushroom like shape at atmospheric chamber pressure but it was disappeared in higher chamber pressure. On the contrary, spray characteristics of the DME became similar to that of diesel under 3MPa of chamber pressure. Hole-to-hole variation of the DME spray was lower than that of diesel in both atmospheric and 3MPa chamber pressures. At 25MPa and 40MPa of DME injection pressures, regardless of chamber pressure, intermittent DME spray was observed. It was thought that vapor lock inside the injector was generated under the two injection pressures.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.9
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• pp.1-8
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• 2020

In this study, the optimal design of the multi-cavity mold layout and packing pressure for the automobile TCU connector cover is determined based on the injection molding analysis and the desirability function method for multi-characteristic optimization. The design characteristics to be optimized are the warpage and sink marks of the product, the scrap of the feed system, and the clamping force. The optimal design is determined by performing injection molding analysis and desirability analysis for design alternatives defined by a complete combination of five mold layouts and six-level packing pressure. The optimal design shows that the desirability values for individual characteristics are quite high and balanced, and the resulting values of individual characteristics are satisfactorily low.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.3
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• pp.50-55
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• 2007

The purpose of this research is to enhance the luminance of the LED and to improve the implementation of color by mounting an array lens on the LED without special technology in process. The workmanship of key components considering the economical efficiency and the injection molding technology for high quality of the product are essential to achieve it. In this paper, the mold was computer-aided was designed and manufactured by CAM software (NX4) and high speed machining center. the applied final machining conditions were 3,000-5,000mm/min feed speed, 15,000-25,000rpm and ${\Phi}0.3mm$ ball end-mill. And the Flow analysis was performed using the mold flow software(MPI) in order to get uniformity of resin. Injection conditions acquired by the flow analysis and the injection experiment are as follows. The cylinder temperature is $220-260^{\circ}C$, the mold temperature is $70-80^{\circ}C$, the injection time is about 1.2sec, the injection pressure and velocity is each 7.8-14.7Mpa, and the injection velocity is 0.8-1.2m/sec.