• International Journal of Automotive Technology
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• v.4 no.4
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• pp.157-164
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• 2003

An experimental and numerical study was performed to investigate the macroscopic and microscopic atomization characteristics of high-speed diesel spray issued from the common-rail injection system. For the experiments, spray visualization system and a phase Doppler particle analyzer system were utilized to obtain the spray atomization characteristics such as the process of spray development, spray tip penetration, and SMD distribution. In order to analyze the process of spray atomization with KIVA-3 code, the TAB breakup model is changed to the KH-DDB competition model, which assumes the competition between the wave instability and droplet deformation causes the droplet breakup above the breakup length. The calculated results were also compared with the experiments in terms of spray tip penetration and SMD distribution. The results provide the process of spray development, axial and radial distribution of SMD, and calculated overall SMD as a function of time after start of injection.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.628-634
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• 1995

In the area of assembly process of micro-chips and electronic parts on the printed circuit board, surface mounting device(SMD) is used as a fundamental tool. Generally speaking, the motion of the SMD is based on the ball screw system operated by any type of actuators. The ball screw system is a mechanical transformer which converts the mechanical rotational motion to the translational one. Also, this system could be considered as an efficient motion device against mechanical backash and friction. Therefore a dynamic modeling and stste sensitivity analysis of the ball screw system in SMD have to be done in the initial design stage. In this paper, a simple mathematical dynamic model for this system and the sensitivity snalysis are mentioned. Especially, the bond graph approach is used for graphical modeling of the dynamic system before analysis stage. And the direct differentiation method is used for the state sensitivity analysis of the system. Finally, some trends for the state variables with respect to the design variables could be suggested for the better design based on the results on the results of dynamic and state sensitivity.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.102-108
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• 1992

To clarify the structure of a diesel spray, a transient non-evaporating diesel spray injected under different ambient pressure and different injection pressure was studied. Spray tip penet- ration and spray angle were measured by taking the high speed shadowgraph of spray and Sauter mean Diameter(SMD) was also measured by light scattering technique at different positions along the spray axis and at different time from the start of injection. The effects of the operating parameters on the spray shape and SMD were investigated. By increasing the injection pressure, the spray tip penetration and the spray angle increased and the change of the ambient pressure also resulted in the considerable change in the shape of the spray. The analysis of SMD measurement showed that the atomization is a process that continues in sp- ace and time. As the injection pressure increases SMD decreases rapidly and with the increa- se of the ambient pressure the atomization process ends faster than the lower ambient press- ure and at lower pressure the atomization process continues to much farther downstream and far afterward.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.1
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• pp.1-8
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• 1994

This study carried out to investigate the spray characteristics of diesel oil through out ultrasonic fuel supply system in comparison with conventional. Size of the droplets comprising diesel spray was measured by immersed liquid method at different positions along the spray axis. Droplets distribution diagram was ploted and Sauter Mean Diameter(SMD) was also calculated. The effects of the ultrasonic vibration and injection pressure on the droplet size distribution and SMD were investigated. As the ultrasonic vibration supply SMD decreases on the same injection pressure conditions with conventional injector's. But the effect of ultrasonic vibration decreases with injection pressure increasing.

• IE interfaces
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• v.10 no.1
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• pp.155-167
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• 1997

The purpose of this study is to develop the program for efficient operation of a multi-functional surface mounting device(SMD) which mount various components on a printed circuit board(PCB). These components are provided by diverse types of feeders such as cassette, stick and tray feeders. The SMD has one or two heads. In the SMD, the positions of PCB and feeders and fixed, and the head moves to pick up a component from a feeder and to mount it on the PCB. The number of lanes occupied by each feeder and the nozzle used for each component can be different. We develop an off-line program to minimize the cycle-time of the SMD by studying the optimal assignment of feeders and the optimal mounting sequence of components. Graphical User Interface(GUI) is also developed. Additionally, we consider the line balancing problem which appears when two SMDs are used sequentially.

• Journal of Korean Library and Information Science Society
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• v.25
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• pp.377-404
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• 1996

The purpose of this study is to investigate material designation in library cataloging and to suggest General Material Designation (GMD) and Specific Material Designation(SMD) in Korean. A summary of the study follows. In library cataloging, methods of indicating the type of material are : (1) color-coding, (2) media code as part of the call number, (3) material designation in physical description area or note area, (4) GMD and SMD. GMD is a term indicating the broad class of material to which a bibliographic item belongs. SMD is a term indicating the special class of material to which a bibliographic item belongs. GMD was listed in parenthesis following the title proper before AACR1975 code, but currently it is listed in square brackets after the AACR1975 code. AACR2 was the standard cataloging rule in GMD and SMD terminology. It is suggested that GMD be used in Korean for graphic material, sound recordings, drawings, microform, multimedia, videorecordings, manuscripts, photographs, slides, printed music, motion pictures, printed texts, objects, braille, cartographic materials, computer files and transparenies.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.384-394
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• 2005

Important characteristics of impinging sprays intersected by a strongly convective gaseous cross flows were experimentally investigated. The breakup processes due to different Weber and Reynolds numbers of liquid and gas streams were visually examined with quantitative measurements of breakup lengths, penetration heights, and droplet sizes. Snapshot images and spay data evidenced that, at lower jet Reynolds number the breakup processes portrays the atomization profiles similar to typical column breakup of single orifice jet. At higher jet Reynolds numbers, disintegration of jet stream is significantly expedited by strong momentum transported from strongly convective gaseous stream. The breakup length and penetration height decreased as the convective flow increase. From the bottom the wall up, the SMD measured the centerline increase. The maximum SMD appeared the top of the SMD distribution

• Journal of Biomedical Engineering Research
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• v.31 no.3
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• pp.194-198
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• 2010

The effective Young’s modulus of a microfibril surrounded by water may be simply calculated by using the upper (Voigt) and lower (Reuss) bounds, which is one way to estimate the Young’s modulus in composite materials. The Steered Molecular Dynamics (SMD) has been used for estimating the Young’s modulus of a microfibril surrounded by water. In this paper, the result estimated by the upper (Voigt) and lower (Reuss) bounds shows 9.2% to 21.8% discrepancy from the result estimated by SMD, but introducing “efficiency of reinforcement parameter” removes the discrepancy and shows good agreement with the result estimated by SMD. We found the best fit for the Young’s modulus against the size of the gap between microfibrils. Also the steps using these bounds are much simpler than SMD.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.291-294
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• 2002

This study describes the external spray characteristics of deflector nozzle such as the breakup procedures of liquid sheet, spray angle, discharge coefficient and bubble behaviors of spray and SMD at deflector nozzle. In order to visualize the spray behaviors shadow graphy technique were used. According to the increase of injection pressure, development of the spray passes through the dribbling, distoted jet, closed bubble due to the contraction by surface tension forces, the bubble opens into hollow tulip shape, and the curved surface straightened to form a conical sheet like as the simplex swirl atomizer. Spray cone angle was nearly 90 deg. Variations of SMD were examined in order to describe the dependency of SMD on the injection pressure and orifice diameter. The shape of deflector and oriffice diameter had an effect on the discharge coefficient.

• Journal of ILASS-Korea
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• v.19 no.3
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• pp.123-129
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• 2014

A diesel spray overall SMD (Sauter mean diameter) in a spray chamber was simulated with CFD by varying the compression ratio in the spray chamber from 18:1 to 100:1. The gas densities of the spray chambers for the compression ratios of 18:1 and 100:1 were 17.97 and $74.8kg/m^3$, respectively. Standard KIVA-3V code was used for the CFD simulation. Various fuel injection patterns such as single injection, pilot injection and split injection were used for the CFD simulation. Fuel injection pressures for the simulated diesel sprays are 90 and 120 MPa. As the compression ratio increases, the CFD simulated SMD was decreased, which was generally in agreement with previous experimental studies.