• 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.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.79-84
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• 2008

For the precision measurement of industrial products, the location of holes inside the products, if they exist, are often selected as feature points. The measurement of hole location would be performed by vision and laser-vision sensor. However, the usage of those sensors is limited in case of big change of light intensity and reflective shiny surface of the products. In order to overcome the difficulties, we have developed a hole displacement measuring device using contact-type displacement sensors (LVDTs). The developed measurement device attached to a robot measures small displacement of a hole by allowing its X-Y movement due to the contact forces between the hole and its own circular cone. The developed device consists of three plates which are connected in series for its own function. The first plate is used for the attachment to an industrial robot with ball-bush joints and springs. The second and third plates allow X-Y direction as LM guides. The bottom of the third plate is designed that various circular cones can be easily attached according to the shape of the hole. The developed system was implemented for its effectiveness that its measurement accuracy is less than 0.05mm.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.156-163
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• 2003

In order to investigate the possibility of punching process of brittle material by ball impact, the effects of sealing materials about impact damage of soda-lime glass by small spheres were evaluated experimentally. The using of sealing materials in the development of perfect cone crack was more effective than no using of sealing materials. At the sealing materials condition, in the case of 5mm-thick specimen, Copper and PMMA sealing were more effective in producing a perfect cone formation than the other sealing materials. And in the case of 8mm-thick specimen, Aluminum sealing was most effective in producing a perfect cone formation. The impact velocity range over which perfect cones were formed was influenced by both the thickness of specimen and sealing materials. By a proper selection of sealing materials, the application fur industrial technology for hole (or nozzle) punching process of brittle materials is expected.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.127-130
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• 2004

For the quality control of the industrial products, an automatic hole measuring system has been developed. The measurement device allows X-Y movement due to contact forces between a hole and its own circular cone and the device is attached to an industrial robot. Its measurement accuracy is about 0.04mm. This movement of the plate is measured by two LVDT sensor system. But this system using the LVDT sensors is restricted by high cost and precision of measurement and correspondence of environment so particularly, a vision system with CCD-Camera is discussed in this paper for the above mentioned purpose. The device consists of two of two links jointed with hinge pins basically and, they guarantee free movement of the touch prove attached on the second link in the same plane. These links are returned to home position by the spring plungers automatically after each process for the next one. On the surface of the touch prove, it has a circular white mark for camera recognition. The system detect and notify the center coordinate of capture mark image through the image processing. Its measuring accuracy has been proved to be about $\pm$0.01mm through the repeated implementation over 200 times. This technique will shows the advantage of touch-indirect image capture idea using cone-shaped touch prove in various symmetrical shaped holes particulary, like tapped holes, chamfered holes, etc As a result, we attained our object in a view of the accuracy, economical efficiency, and functionality

• Journal of the Optical Society of Korea
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• v.13 no.1
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• pp.48-52
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• 2009

Micro-hole targets are studied to generate energetic protons from laser-thin foil targets by using 2-dimensional particle-in-cell simulations. By using a small hole, the maximum energy of the accelerated proton is increased to 4 times higher than that from a simple planar target. The main proton acceleration mechanism of the hole-targets is the electrostatic field created between the fast electrons accelerated by the laser pulse ponderomotive force combined with the vacuum heating and the target rear surface. But in this case, the proton angular distribution shows double-peak shape, which means poor collimation and low current density. By using a small cone-shaped hole, the maximum proton energy is increased 3 times higher than that from a simple planar target. Furthermore, the angular distribution of the accelerated protons shows good collimation.

• International Journal of Automotive Technology
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• v.6 no.1
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• pp.9-14
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• 2005

An experimental investigation has been carried out to reveal the atomization process of the diesel fuel spray. The spray injected through a single hole nozzle was taken by a camera on the opposite side of a stroboscope for macroscopic observation or a nanolite for microscopic observation. The effect of nozzle aspect ratio was analyzed with disintegration phenomena of the diesel spray. Based on the enlarged spray photograph, atomization process was observed in detail and further the spray cone angle was measured under various ambient pressures. The result shows that atomization of diesel spray in early stage of injection is mainly progressed in the vicinity of spray periphery region except the region close to the nozzle exit and spray head region. The spray cone angle is nearly constant under the pressurized condition, while it decreases with elapsing time under the atmospheric condition.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.766-775
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• 2003

The intermittent spray characteristics of a multi-hole diesel nozzle with a 2-spring nozzle holder were investigated experimentally. Without changing the total orifice exit area, the hole number of the multi-hole nozzle varied from 3 (d$\_$n/=0.42 mm) to 5 (d$\_$n/=0.32 mm). The time-resolved droplet diameters of the spray including the SMD (Saute. mean diameter) and the AMD (arithmetic mean diameter), injected intormittently from the multi-hole nozzles into still ambient ai., were measured by using a 2-D PDPA (phase Doppler particle analyze.). The 5-hole nozzle spray shows the smaller spray cone angle, the decreased SMD distributions and the small difference between the SMD and the AMD, compared with that of the 3-hole nozzle spray. From the SMD distributions with the radial distance, the spray structure can be classified into the three regions : (a) the inner region showing the high SMD distribution , (b) the mixing flow region where the shea. flow structure would be constructed : and (c) the outer region formed through the disintegration processes of the spray inner region and composed of fine droplets. Through the SMD distributions along the spray centerline, it reveals that the SMD decreases rapidly after showing the maximum value in the vicinity of the nozzle tip. The SMD remains the constant value near the Z/d$\_$n/=166 and 156.3 for the 3-hole and 5-hole nozzles, which illustrate that the disintegration processes of the 5-hole nozzle spray proceed more rapidly than that of the 3-hole nozzle spray.

• KCID journal
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• v.2 no.1
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• pp.57-64
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• 1995

현장 투수시험 방법 중에서 Borehole type의 Boutwell Permeameter와 Constant head bore-hole permeameter, 그리고 Porous probe type의 cone shaped porous probe(BAT Permeameter)에 대한 내용을 간단히 소개하였고, 각 측정법의 특징을 비교분석한 내용을 요약하면 (표-1)과 같으며, 기회가 있으면 Infiltrometer type와 Underdrain type에

• Journal of computational fluids engineering
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• v.15 no.1
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• pp.56-63
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• 2010

Since emission regulations for vehicles have become more stringent, SCR technology has drawn a strong attention in order to reduce NOx emissions. Optimal design of a reductant injection nozzle and a multi-hole plate located between the cone and catalyst is critical in that the uniform distribution of reductant is necessary to maximize the NOx conversion efficiency and minimize the slip of reductant in SCR. In this work, an LPG fuel(C3H8 in vapor state) was used as a reductant for LPG vehicles. A Realizable k-$\varepsilon$ model is used for turbulence, and SCR body is defined as porous media with inertia and viscous resistances measured in this work. Effect of the number of nozzle holes on the flow mixing index was analyzed, which revealed that a four hole nozzle shows the best performance in terms of uniformity of flow. An installment of a multi-hole plate at the entrance of catalyst was evaluated with flow mixing index, uniformity of flow, and pressure drop. A multi-hole plate with gradual hole diameter change in three steps showed the best uniformity of flow within the conditions suggested in this work.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.193-199
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• 2000

The effects of Reynolds number on the non-nulling calibration of a cone-type five-hole probe in low-speed flows have been investigated at the Reynolds numbers of $2.04{\times}10^3,\;4.09{\times}10^3$, and $6.13{\times}10^3$. The calibration is conducted at the pitch and yaw angles in ranges between -35 degrees and 35 degrees with an angle interval of 5 degrees. The result shows that each calibration coefficient, in general, is a function of the pitch and yaw angles, so that the pre-existing calibration data in a nulling mode are not enough in accounting for the full non-nulling calibration characteristics. Due to the interference of the probe stem, the calibration coefficients have more Reynolds number sensitivity at positive pitch angles than at negative ones.