• Coupled systems mechanics
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• 제7권5호
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• pp.627-634
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• 2018

Laser beam welding is more advantageous compared to conventional methods. Titanium/Aluminium dissimilar alloy thin sheet metals are difficult to weld due to large difference in melting point. The performance of the weldment depends upon interlayer formation and distribution of intermetallics. During welding, aluminium gets lost at the temperature below the melting point of titanium. Therefore, it is needed to improve a new metal joining techniques between these two alloys. The present work is carried for welding TI6AL4V and AA2024 alloy by using Nd:YAG Pulsed laser welding unit. The performance of the butt welded interlayer structures are discussed in detail using hardness test and SEM. Test results reveal that interlayer fracture is caused near aluminium side due to low strength at the weld joint.

• 한국분무공학회지
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• 제5권1호
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• pp.23-29
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• 2000

Recently the laser sheet technique has been developed to improve our limited understanding of the in-cylinder diesel combustion. The technique is capable of high temporal and spatial resolution, so that it is proved to be an adequate combustion diagnostics to find out exhaust emission formation. The optical signals of LIS(Laser Induced Scattering) and LII(Laser Induced Incandescence) images show informations for soot concentration within the optically accessible diesel engine. The LIS and LII signal images of soot concentration provide new insight into where and when soot occurs in a diesel engine.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2010년도 춘계학술발표대회 초록집
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• pp.96-96
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• 2010

Magnesium alloy is being used for structural material since it has high specific strength. Tubular shape was effective way for enhanced structural design. To manufacture the tube, it is necessary to weld the butted joint of both tubular formed sides. But the magnesium alloy was hardly welded with conventional welding processes. The laser welding was effective way to joint magnesium alloys because it had high weld strength and productivity compare with other welding processes. In this study, magnesium alloy sheets was formed at elevated temperature to tubular shape and welded with laser. Consequently, the magnesium alloy tube was making successful with warm forming and laser welding and bicycle frame was making with it.

• Journal of Welding and Joining
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• 제19권1호
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• pp.104-111
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• 2001

This study presents an analysis method for heat flow and deformation of sheet metal laser welding. A heat source model for 2-dimensional heat flow analysis of laser welding process was suggested in this paper. To investigate the availability of the heat source model, the analysis results were compared and estimated with the results of previous researches. We could get a good agreement between the results of numerical analysis and experiments in the temperature distribution of weldment. Due to the characteristics of welding process, some kinds of deformations are usually generated in a welded structure. Generally, the degree of deformation is dependent on the welding sequence constraints as well as input power Therefore, in this paper we evaluate the deformation of gas pressure vessel according to the welding sequence and input power. In the analysis of weld deformation, 2-dimensional thermo-elasto-plastic analysis was performed for the gas pressure vessel by using a commercial FE program package.

• 한국자동차공학회논문집
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• 제5권6호
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• pp.167-174
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• 1997

The penetration depth and the size distribution of the droplets of fuel sprays are important in the operation of spark-ignition MPI engines. A fluorescence/scattering image technique for droplet sizing was applied to measure th edroplet size distribution in non-evaporating gasoline sprays. The fluorescence and scattering lights were imaged simultaneously by the two-dimensional visualization system composed of a laser sheet, a doubling prism, optical filters, and a CCD camera. Quantitative droplet size distributions were extracted from evaluating the ratio of the two light densities. The mean droplet size measured by the fluorescence/scattering technique was compared with the result obtained by the enlarged photographs of droplets. The fluorescence/scattering image technique also gives the useful information of the characteristics of droplet impingement in a inclined wall.

• 한국분무공학회지
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• 제5권1호
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• pp.41-48
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• 2000

In this research, the velocity distribution of the liquid sheet formed by two impinging jets at low velocities are measured using LDV. The spatial distribution of the sheet velocity as well as the effects of impinging anlge and jet velocity on the sheet velocity are examined. The sheet velocity is highest along the sheet axis and it decreases with the increase of the azimuthal angle. With the increase of the impinging angle, the average sheet velocity is decreased due to the increased impact momentum. The average sheet velocity is proportional to the jet velocity but it is always higher than the jet velocity. This result is against the fact that the sheet velocity can be assumed to be equal to the jet velocity in the previous researches.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.728-733
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• 2000

In this research, the velocity distribution of the liquid sheet formed by two impinging jets at low velocities are measured using LDV. The spatial distribution of the sheet velocity as well as the effects of impinging angle and jet velocity are examined. The sheet velocity is the highest along the sheet axis and it decreases with the increase of the azimuthal angle. With the increase of the impinging angle, however, the difference of sheet velocity on the liquid sheet is decreased. The average sheet velocity is proportional to the jet velocity but it is always higher than the jet velocity as against the fact that the sheet velocity can be assumed to be equal to the jet velocity in the previous researches.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 추계학술대회 논문집
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• pp.108-111
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• 2004

Laser induced incandescence and laser induced fluorescence techniques have been investigated to measure the concentrations of soot and PAH, respectively. The Nd:YAG and dye lasers were used to form a sheet beam, and its wavelength were modulated to obtain a optimized signals of soot and PAH. Results showed that the relative size groups of soot and PAH can be measured by using our laser techniques.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 1998년도 춘계학술발표대회 초록개요집
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• pp.29-30
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• 1998

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2000년도 춘계학술발표대회 논문개요집
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• pp.11-14
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• 2000