• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.60-68
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• 1997

Rayleigh Scattering Cross Sections($\sigma$i) of various gases and the temperature distributions of premixes C3H8/O2 flame are measured by high power KrF(248nm) Exci- mer laser and ICCD camera. Results show that $\sigma$i of O2 and Propane(C3H8) gases agree well in the 5% error range, but of H2 has the more or less difference from the calcul- ated value by other groups. This is attributed to the low RS signal of H2 to Nosie level(S/N ratio). The temperature distributions of flame range out between 300K in the air and about 2000K in the burned area. In this temperature range, out system has the about 250K temperature resolution. Because low RS signals in the reaction area with high temperature are affected highly by noises, temperature uncertainty of this area is relatively high to another part of flame. Experimental results show that UV Rayleigh Scattering can be used for the measurement of mixing ratio of mixed gases and the temperature distributions of flame. Especially, this technique can be applied for the measurement of the mixing ratio of air/fuel before the ignition and the flame structure after the ignition inside the Engine.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.186-189
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• 2008

The flex plate, an automotive part which mounts to the automotive engine to transfer torque to transmission, should have considerable hardness and shape accuracy. As a way to produce the flex plate, the hot press forming technology which takes advantages of high formability at elevated temperature, enhanced strength and shape stability was introduced. Therefore, as one of major process parameters the heat treatment condition should be determined to obtain appropriate hardness in the range of manufacturer's specifications. In this study, two heat treatments, austempering and quenching and tempering (QT), were compared as feasible conditions fur the hot press forming of high-carbon tool steel and the hardness and toughness after heat treatments were evaluated. The study showed that both heat treatments resulted in improved hardness but only quenching and tempering showed practicable range of toughness.

• Tribology and Lubricants
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• v.14 no.2
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• pp.63-74
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• 1998

The damage of cam/tappet surface is one of the major reasons for energy loss in an I.C. engine. High friction causes the accelerated wear of the cam/tappet surfaces which in turn changes the valve opening/closing timing. During the accelerated test evidence of both rolling fatigue and sliding abrasive wear could be found. Based on the results of the accelerated test, a scheme was devised to decrease tappet wear. Wear reduction of the tappet was achieved by using undulated surface topography in the tappet center region. The wear reduction is achieved by trapping of the wear particles in the undulations as well as by increasing the supply of lubricant to the sliding interface.

• Journal of ILASS-Korea
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• v.4 no.1
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• pp.13-18
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• 1999

It has been known that spray characteristics have an important effect on the mixture formation and directly influence the engine performances and the emissions. Up to now, the measurement of droplet size is well developed such as PDPA and PMAS though the behavior of small droplets during secondary atomization is not clear. Particle image velocimetry(PIV), a planar measuring technique, is a very efficient tool for studying complicated behavior and a fast and reliable method to track numerous droplets during injection. In this study, two-color scanning PIV is designed to obtain quasi-instantaneous two dimensional velocity data by using he-ion laser, rotating mirror and beam splitter. This PIV method which has high temporal and spatial resolution provides the information about the small complex droplet behavior.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.71-79
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• 1992

Recently, air pollution and energy security problems have necessitated the development of alternative fuel vehicles. As an alternative fuel vehicle FFV(Flexible Fuel Vehicle) which can be operated by and mixture between gasoline and M85(methanol 85% and gasoline 15% by vol. percent) has been drawing great attention. But poor cold startability of high methanol- content fuel which is characteristic of lower fuel volatility and higher latent heat of vaporization than gasoline is one of the major problems to be solved for the development of FFV. In this paper, important factors influencing cold startability of general S.I. engines are described. And, so-me cost-effective and practical methods were investigated in view of the optimization of fuel-ing parameters and ignition system for M85 fuel. The test results showed good startability up to (-22)-(-23).deg.C.

• Publications of The Korean Astronomical Society
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• v.26 no.4
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• pp.159-168
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• 2011

We constructed two test server systems for KMTNet data management. One is the photometry database server which is optimized for stable operation, and the other is the photometric data process server which is optimized for fast I/O between devices. The performances of servers and data storage units were tested using various methods. Database upload was also checked using five different methods. From tests, we concluded that the most efficient method to upload photometric data processing results to database is the use of three nodes with job scheduler under the InnoDB engine. In this study we provide the test results for prototype servers for KMTNet data management.

• Journal of Power System Engineering
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• v.10 no.2
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• pp.16-21
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• 2006

On this study, numerical analysis was performed for the 3 dimensional flow field of gas and particle phase for axial inlet cyclone, a part of dust collector. We applied FVM to visualize the gas phase. The flow was solved using ${\kappa}-{\varepsilon}$ turbulence model. The major parameters considered in this study were helical guide vane, inner diameter, length. Particle trajectory calculations were performed for the particle sizes of $5{\mu}m{\sim}75{\mu}m$. The distribution curve of particle sizes was made of Rosin-Rammler function. The simulation results show various gas flows, particle trajectories on numerical models.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.19-25
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• 1998

Remote fault diagnosis and maintenance system using general telecommunication network is necessary for an effective fault diagnosis and higher productivity of NC machine tools. In order to monitor machine tool condition and diagnose alarm states due to electrical and mechanical faults, a remote data communication system for monitoring of NC machine fault diagnosis and status is developed. The developed system consists of (1) remote communication module among NC's and host PC using PSTN. (2) 8 channels analog data sensing module, (3) digital I/O module for control or NC machine, (4) communication module between NC machine and remote data communication system via RS-232C, and (5) software man-machine interface. Diagnostic monitoring results generated through a successive type inference engine are displayed in user-friendly graphics. The validity and reliability of the developed system is verified to be a powerful commercial version on a vertical machining center through a series of experiments.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1019-1021
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• 1999

In this paper, we describe the design and appliance of the preventive diagnostic expert system of gas in oil for power transformer. This expert system is developed to use expert system development tool; Element Expert (NEURON DATA Inc.) Analysis is developed by four diagnose methods. In first, the standard of KEPCO is applied. It classifies the state of transformer by four level: Normal, warning, abnormal and danger. And the others are gas pattern methods, IEC code method, and Dornen & Roger Ratio method and applied later. These latter methods analyse the cause of result. Inference engine was designed with Element Expert. In last, we operate the system with sample data and we can obtain the correctly inferred result for the state of transformer.

• Journal of Power System Engineering
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• v.14 no.1
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• pp.11-15
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• 2010

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions from the diesel engines are recognized as main cause which has a great influence on environment. In this study, the potential of biodiesel fuel and oxygenated fuel(ethylene glycol mono-n-butyl ether; EGBE) was investigated as an effective method of decreasing the smoke emission. The smoke emission of blending fuel(EGBE 0~20 vol-%) was reduced in comparison with diesel fuel and it was reduced approximately 64% at 2000 rpm, full load in the 20% of blending rate. On the contrary NOx emissions from biodiesel fuel and EGBE blended fuel were increased compared with diesel fuel. Torque and brake specific energy consumption(BSEC) didn't have large differences.