• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1995.10a
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• pp.24-29
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• 1995

A recently developed finishing process using rotating magnetic field is known to be very efficient for the finishing of parts such as vacuum tube, sanitary tube, etc., which are difficult to be finished by the conventional finishing methods as they are generally curbed tubes. But, the finishing system using rotating magnetic field have the defect that is the cross section of workpiece only circle because of internal rotating tool. Therefore, new finishing process of the workpieces which cross section are not circle is important and required. magnetic abrasive jet machining is a new concept finishing process. It is the precision internal finishing method using working fluid mixed with magnetic abrasives, which is jetted into the internal surface of tube. And magnetic poles are equipped on external surface of tube. In this study new concept finishing process or, magnetic abrasive jet machining system was developed. machining condition was predicted using simulation and some characteristics of the finishing process was analyzed.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.181-182
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• 2003

경유엔진은 가솔린엔진에 비해 연소특성상 연료소비효율이 우수하여 온실가스인 $CO_2$ 배출이 적은 반면 대기 및 인체위해성이 높은 NOx와 입자상물질(PM)의 배출이 많아 대기저감을 위한 연료의 고압분사, 전자제어식 EGR기술등 엔진개량기술과 매연여과장치, De-NOx등 후처리기술 그리고 대체연료사용 기술등 다양한 저감대책이 전세계적으로 강구되고 있다. 특히 경유엔진에서 배출되는 오염물질로 인한 대기오염영향은 점차 증가하고 있어 대체연료사용 및 배출허용기준강화둥 우리 실정에 적합한 효율적인 대기저감대책이 강구되어야 할 것이다. (중략)

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.5
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• pp.103-110
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• 2000

A two phase compound jet, which mixes pulverized solid particles with the air in the test section, is experimentally analyzed in this study. Two phase flow is jetted 10 degree upward in the primary jet, while the secondary jet utilizes the air only. The height difference between the primary and secondary central axises is 32.5mm. The velocity vector field, concentration field, and turbulent properties of solid particles are measured by using 3-Dimensional Particles Dynamics Analyzer. When the jet angle of the secondary jet goes into effect, the solid particle recirculation zone becomes larger. Also, solid particle concentration becomes more dense due to a velocity decrement of particles.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.925-930
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• 2000

This paper is investigated the entrainment of air into sprays which has significant effects on the combustion efficiency, stability of flame using the air-assisted twin-fluid nozzle in non-burning. The factors which may be expected to affect the entrainment of air by a liquid spray are: Relative velocity of droplet and ambient gas; Drop size and size distribution; Density and other property of the liquid. Here, axial, radial velocity and turbulent kinetic energy of spray droplet was measured with the PIV(Particle Image Velocimetry). Spray characteristics were also visualized using CCD camera. The results indicate that the entrainment rate increases more or less non-linearly with the downstream region.

• The KSFM Journal of Fluid Machinery
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• v.14 no.6
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• pp.85-90
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• 2011

Recently, many high elevation fountain are constructed for the beauty of beach landscape. Typically, a fountain has several nozzles that shoots water upwards or at an angle into the air. But unfortunately, the weather and wind can cause the water soak nearby walkways and pedestrians. Therefore, in this study, a mathematical model of high elevation fountain is suggested to predict the actual travelling distance of water droplet by the wind. To simplify our treatment of the water flow and to avoid issues such as fluid dynamics and surface tension, we have adopted a particle model for the fountain water. The particles are assumed not to interact with each other, and do not deform during their flight through air.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.225-230
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• 2003

The major purpose of this study is to find the optimized split injection quantities and dwell angles for PM reduction without increasing NOx. The tests were performed on a Common-Rail DI Diesel Engine to obtain optimum injection timing and duration. In this study, total injection quantities were divided into the ratio of 25-75%, 50-50% and 75-25%. NOx and PM were measured on the condition of the same bsfc by increasing dwell angles. It was found that the split injection reduced NOx with dwell angle increase. For 50_50, 75_25% split injection cases, PM was reduced with 10 to 12(CAD) dwell angles. For 25_75% split injection 33% PM reduction was achieved with 8 to 12(CAD) dwell angles.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.19-26
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• 2002

The objective of this study is to examine a DI(Direct Injection) gasoline spray development process under different ambient pressures using PIV(Particle Image Velocimetry). fuel spray experiments were performed within a constant volume chamber. The spray structure, velocity maps, velocity and vorticity contours were obtained to investigate its spray characteristics. It was found that higher ambient pressure has a significant effect on radial growth of the spray. The position which has a maximum velocity moved from the spray edge to the spray center as ambient pressure was increased. Higher ambient pressure moved a maximum vorticity position upward of the spray.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.86-95
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• 1996

This study was on the pollution emissions of the Ultrasonic fuel feeding system in gasoline injection vehicle. This work measured th SMD of the fuel, and compared the characteristics through chassis dynamometer and highway road test by the conventional vehicle. And this work measured vacuum degree, turbulence intensity and the rate of fuel consumption according to intake air velocity with swirler. The results are as followed; The effects of the vehicle installed the ultrasonic fuel feeding system are better than those of the conventional vehicle.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.219-227
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• 1998

This paper describes the fuel spray characteristics of gasoline port injectors such as the breakup procedures of liquid fuel, breakup and extinction behaviors of fuel spray at nozzle tip, time history of SMD and velocity distribution of fuel spray in the direction of fuel stream. Pintle-type gasoline fuel injector was used to analyze mentioned spray characteristics. In order to visualize the fuel spray behaviors and to measure the droplet mean diameter and velocities of spray droplets, the Schlieren method, digital image processing and auto-correlation PIV were applied in this study. In addition, the spray characteristics according to the variation of time were considered. The results of fuel spray show that the liquid sheet breakup starts at 10mm downstream actively. The flying time is approximately 4msec between 50mm and 80mm down the nozzle tip. Also, SMD of fuel spray, the number of droplets and fuel velocity distribution at each point of downstream are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.4
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• pp.99-106
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• 2010

A piezo-driven injector was applied with a purpose to evaluate the effect of induced voltage on spray characteristics. For this, injection rate, macroscopic imaging, ambient gas entrainment and particle sizing were carried out. It was shown that initial slope of injection rate was steeper as induced voltage increased, while slope of injection rate became mostly constant with fully opened needle. From macroscopoic imaging, longer spray tip penetration was produced with higher induced voltage. Moreover, wider spray angle was detected in the early stage of spray development, when higher induced voltage was applied. Ambient air entrainment rate was increased and particle size was reduced with higher induced voltage.