• 대한기계학회논문집B
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• 제26권12호
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• pp.1655-1662
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• 2002

Recently, many researches have been performed to improve the performance of the combustion and emission in a D.I.Diesel engine. And many new techniques have been introduced and developed to reduce NO$_{x}$ and soot exhausted from diesel combustion. Some of these methods have the peculiar injection timing which is not used to traditional timing. To optimize these injection timing, characteristics of swirl flow and interaction of swirl with injection in the diesel engine should be investigated more carefully. Therefore, in this study, 2-zone energy method is adopted for the understanding of swirl flow in condition of moving piston, and then flame visualizations and image process are performed. From these studies, the characteristics of the swirl flow generated by SCV was investigated and the effect of swirl on injection timing was elucidated. As the results, velocity distribution caused by swirl flow increase the space utilization rate of flame plums. And flame plums of weak momentum are remained inside of combustion chamber by the swirl flow.w.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.214-219
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• 2002

As the tangential flow inside the clearance of tribe elements such as bearings and seals is increased as the shaft speed increases, the system stability will be decreased due to the increment of the instability parameter. To reduce the tangential flow inside the clearance of the balance sleeve, anti-swirl injection mechanism is applied. The balance sleeve is used in resisting the axial force induced by impeller in high pressure multi-stage pump. In this paper, total three cases are experimentally investigated; original balance steeve, anti-swirl injection balance steeve with 0 axial degree and anti-swirl injection balance sleeve with 30 axial degree. Experiments are focused in the comparison of vibration level and leakage flow rate. The results clearly shows that the anti-swirl injection balance sleeve with 0 axial degree improves the vibration characteristics. However, the anti-swirl injection balance sleeve with 30 degree aggravates the vibration characteristics. In the standpoint of leakage performance, both anti-swirl injection balance sleeves show the better result than the original balance sleeve.

• 한국소음진동공학회논문집
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• 제12권8호
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• pp.632-638
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• 2002

As the tangential flow inside the clearance of tribo elements such as bearings and seals is increased as the shaft speed increases, the system stability will be decreased due to the increment of the instability parameter. To reduce the tangential flow inside the clearance of the balance sleeve, anti-swirl injection mechanism is applied. The balance sleeve is used in resisting the axial force induced by impeller in high pressure multi-stage pump. In this paper, total three cases are experimentally investigated; original balance sleeve, anti-swirl injection balance sleeve with 0 axial degree and anti-swirl injection balance sleeve with 30 axial degree. Experiments are focused in the comparison of vibration level and leakage flow rate. The results clearly shows that the anti-swirl injection balance sleeve with 0 axial degree improves the vibration characteristics. However, the anti-swirl injection balance sleeve with 30 degree aggravates the vibration characteristics. In the standpoint of leakage performance, both anti-swirl injection balance sleeves show the better result than the original balance sleeve.

• 한국화재소방학회논문지
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• 제5권2호
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• pp.11-20
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• 1991

Dilute polymer solutions were injected into turbulent pipe flow of a Newtonian fluid. The local drag reduction for injection of polymer solution at the pipe wall was larger than that at centerline. From the above result we may conclude that the polymer additives were found to influence the flow in the neighborhood of the wall. The effects of the injection apparatus on the local drag reduction are small compared to the drag-reducing effects. The extent of drag reduction increased with polymer concentration and injection flow rate, and the maximum drag reduction obtained were 47% for Polyox Coagulant and 35% for Separan AP-273. In respect to polymer degradation, the polyacrylamide showed better shear stability than the polyethyleneoxide and thus the former expected to have a sharper molecular weight distribution.

• 한국공작기계학회논문집
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• 제17권4호
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• pp.89-94
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• 2008

Differential pressure flow meters which have a shape of triangular separate bar(TSB) were tested for investigating the flow rate characteristics of the flow meters with varying the temperature of the gas flow. Three kinds of the triangular separate bar flow meters whose aerodynamic angles are different one another are used. The mass flow rate of the flow meters are evaluated using a non-dimensional parameter which includes the gas temperature, exhaust gas pressure and differential pressure at the flow meters, and atmospheric pressure. A burner system which is similar to gas turbine was used for raising the gas flow temperature. The burner system was operated with varying the air/fuel ratio by controlling both the fuel injection rate from the fuel nozzle and air flow rate from a blower. An empirical correlation between the mass flow rate at the TSB flow meter and the non-dimensional parameter was obtained. The empirical correlation showed linear relationship between the mass flow rate and the non-dimensional parameter H. Also, the mass flow rate characteristics at the TSB flow meter was affected by the gas temperature.

• 한국지하수토양환경학회지:지하수토양환경
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• 제23권1호
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• pp.1-13
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• 2018

A series of experiments using transparent micromodels with an artificial pore network etched on glass plates was performed to investigate the effects of flow rate on the migration and distribution of resident wetting porewater (deionized water) and injecting non-wetting fluid (n-hexane). Multicolored images transformed from real RGB images were used to distinguish n-hexane from porewater and pore structure. Hexane flooding followed by immiscible displacement with porewater, migration through capillary fingering, preferential flow and bypassing were observed during injection experiments. The areal displacement efficiency increases as the injection of n-hexane continues until the equilibrium reaches. Experimental results showed that the areal displacement efficiency at equilibrium increases as the flow rate increases. Close observation reveals that preferential flowpaths through larger pore bodies and throats and clusters of entrapped porewater were frequently created at lower flow rate. At higher flow rate, randomly oriented forward and lateral flowpaths of n-hexane displaces more porewater at an efficiency close to stable displacement. It may resulted from that the pore pressure of n-hexane, at higher flow rate, increases fast enough to overcome capillary pressure acting on smaller pore throats as well larger ones. Experimental results in this study may provide fundamental information on migration and distribution of immiscible fluids in subsurface porous media.

• 한국자동차공학회논문집
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• 제15권3호
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• pp.99-105
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• 2007

Currently, BLDC fuel pump was applied on LPi vehicle using 3rd fuel supply system as liquified phase LPG injection method had already shown better performance than others. Its cost, however, is rather expensive because of drawbacks such as complicated structure, a fault of localization of system. In this work, demonstration system for a developed turbine type fuel pump to replace BLDC system was setup and investigated. This study results that fuel mass flow rate of turbine type pump and injection performance of injector were better compared to BLDC type. Comparing flow rate of summer LPG with that of winter LPG, the flow rate decreased about 25% using winter LPG. Performance applying turbine type LPi fuel pump to engine is confirmed.

• Journal of the Korean Wood Science and Technology
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• 제45권4호
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• pp.471-481
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• 2017

As the molecular weight (MW) of urea-formaldehyde (UF) resins had a great impact on their properties, this work was conducted to study effect of analytical parameters of gel permeation chromatography (GPC) on the MW measurement of UF resins. GPC parameters such as flow rate, column, detector temperature, and sample injection temperature were selected to compare number-average molecular weight (Mn), weight-average molecular weight (Mw), molecular weight distribution (MWD) and polydispersity index (PDI) of two UF resins with different viscosities. As expected, UF resin with higher viscosity resulted in greater Mn and Mw than those of low viscosity UF resin. When the flow rate increased, both Mn and Mw of UF resins decreased and MWD became narrower. By contrast, both Mn and Mw increased and MWD became wide when the column, detector, and sample injection temperature increased. The column, detector, and sample injection temperature of $50^{\circ}C$ at a flow rate of $0.5m{\ell}/min$ resulted in the highest MW and broadest MWD for the GPC analysis. These results suggest that the apparent molecular size or a hydrodynamic radius of UF resin molecules dissolved in the mobile phase affect to Mn, Mw and MWD.

• 대한기계학회논문집B
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• 제28권11호
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• pp.1376-1383
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• 2004

In the present work, a series of experiments have been performed on electro-hydrodynamic atomization of non-conducting liquid using a charge injection type nozzle. Effects of liquid flow rate, input voltage, and distance between the needle and the ground electrode (nozzle-embedded metal plate) have been examined. For fixed electrode distances, total and spray currents increase with the increase of liquid flow rate and input voltage. When the distance between the needle tip and the ground electrode becomes closer, the total, leakage and spray currents increase, while the onset voltage for the dielectric breakdown decreases. When the electric field strength of the liquid jet exceeds that for the air breakdown, a portion of the electric charges in the liquid jet is dissipated into the ambient air, and the charge density shows a limiting value. Atomization quality can be improved by increasing the liquid flow rate due to the higher charge density and the enhanced aerodynamic effect.

• International Journal of Automotive Technology
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• 제6권4호
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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.