• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.723-736
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• 1999

Code optimization phase in a compiler are very important because the phase reduces the running time and the storage size of machine codes. I developed flow analyzers and optimizers on intermediate codes. The flow analyzers generate control-flow and data-flow information. The optimizers transform the intermediate codes into the improved codes using this information. This paper describes the development of flow analyzers and optimizers. I also examined the execution performance, the cost and the dependency of each optimization.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.6
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• pp.1330-1335
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• 2001

A present study is the flow characteristics of impinging jet by PIV measurement and numerical analysis. The flow characteristics of impinging jet flow are affected greatly by nozz1e inlet velocity An circular sharp edged nozzle type($45^{\circ}$ ) was used to achieve uniform mean velocity at the nozz1e inlet, and its diameter is 10 mm(d). Therefore, the flow characteristics on the impinging jet can be changed largely by the control of main flow In this parent study, we investigate the effects of inlet velocity, its variable is nozzle inlet Reynolds numbers (Re=1500, 3000, 4500, 6000 and 7500)

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.1
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• pp.47-53
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• 2008

The effect of periodic blowing and suction of upstream flow on the separated shear flow behind the vertical fence was experimentally investigated. The fence was submerged in the turbulent shear flow and DPIV method was used to measure the instantaneous velocity fields around the fence. Periodic blowing and suction flow was precisely generated by the syringe pump. Spanwise nozzle made 2D planar periodic jet flow in front of the fence and the effect of frequency and maximum jet velocity was studied. From the results, the reattachment length can be reduced by 60% of uncontrolled fence case under the control.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.3
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• pp.763-770
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• 1995

Gas flow characteristics within the cylinder is important factors in impoving lean combustion stability. This paper shows the effects of various flow fields generated by a swirl control valve(SCV) on combustion process in a 4-valve spark ignition engine. An impulse swirl/tumble meter was used to elucidation the steady-state flow characteristics, and a rotating grating type LDV was developed to measure the mean velocity and tunbulence intensity in relation to the crank angle. These methodologies were applied to clarify the correlation between gas flow characteristics and combustion stability at a lean air fuel ratio. An analysis of the correlation revealed the gas flow conditions required to optimize a lean-burn system.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.551-556
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• 2001

The filling pattern technique based on the finite element method and Eulerian mesh advancement approach has been developed to analyze incompressible transient viscous flow with free surfaces. The governing equation for flow analysis is Navier-Stokes equation including inertia and gravity effects. The penalty and predictor-corrector methods are used effectively for finite element formulation. The flow front surface and the volume inflow rate are calculated using the filling pattern technique to select an adequate pattern among four filling patterns at each triangular control volume. Using the proposed numerical technique, the collapse of a dam has been analyzed to predict flow phenomenon of fluid and the predicted front positions versus time have been compared with the reported experimental result.

• KCI Concrete Journal
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• v.13 no.1
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• pp.35-41
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• 2001

This paper investigated rheological properties of binder pastes for self-compacting high performance concrete. Six mixtures of self-compacting concrete were initially prepared and tested to estimate self-compacting property. Then, the binder pastes used in self-compacting concrete were tested for rheological properties using a rotary type rheometer. Binder pastes with different water-binder ratios arid flow values were also examined to evaluate their rheological characteristics. The binders were composed of ordinary Portland cement, fly ash, two types of pulverized blast-furnace slag, and limestone powder. The flow curves of binder pastes were obtained by a rotary type rheometer with shear rate control. Slump flow, O-funnel time, box, and L-flow teats were carried out to estimate self-compacting property of concrete. The flow curves of binder pastes for self-compacting concrete had negligible yield stresses and showed an approximately linear behavior at higher shear rates beyond a certain limit. Test results also indicated that the binders incorporating fly ash are more appropriate than the other types of binders in quality control of self-compacting concrete.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.34-37
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• 2004

Recently advancing mobile communication tools and I.T industry, semiconductor device is requested more integrated, faster operation time and more scaled-down. Because of these reasons semiconductor device is requested multilayer interconnection. For the multilayer interconnection chemical mechanical polishing (CMP) becomes one of the most useful process in semiconductor manufacturing process. In this experiment, we focus on understand the characterize and improve the CMP technology by control of slurry flow rate. Consequently, we obtain that optimal flow rate of slurry is 170ml/min, since optimal conditions are less chemical flow and performance high with good selectivity to Ta. If we apply this results to copper CMP process. it is thought that we will be able to obtain better yield.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.494-499
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• 2011

One of the devices to prevent separated flow over a wing or a flap at high angle of attack is a vortex generator. In the present work, we numerically study the flow around a low-profile or micro vortex generator whose height is less than local boundary layer thickness which can delay separation with a minimum drag penalty owing to its very small wetted surface area. As a first step toward a parametric study to efficiently design this MVG flow control system, we simulate the flow around a single MVG on a flat plate. For the simulation, we employ OpenFOAM with Launder-Sharma ${\kappa}$-epsilon model. The analysis results are validated by comparing with experimental results of a rectangular MVG at an angle of attack of 10 degrees whose height is 20% of local boundary layer. Important results and aspects of this numerical study are discussed. We also simulate the flow around rectangular, triangular and trapezoidal MVGs and the results are compared

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.34-39
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• 2001

A present study is the flow characteristics of impinging jet by PIV measurement and numerical analysis. The flow characteristics of impinging jet flow are affected greatly by nozzle inlet velocity. An circular sharp edged nozzle type($45^{\circ}$) was used to achieve uniform mean velocity at the nozzle inlet, and its diameter is 10mm(d). Therefore, the flow characteristics on the impinging jet can be changed largely by the control of main flow. In this parent study, we investigate the effects of inlet velocity, its variable is nozzle inlet Reynolds numbers(Re=1500m 3000, 4500, 6000 and 7500)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.433-436
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• 2011

The effect of plasma on flow characteristics in subsonic flow in backward-facing step is studied. The velocty of main flows are 0.5 m/s. DBD plasma is using for flow control. Stainless foil and polymide films are used as an electrode and dielectric material. The change of flow characteristics are shown by different of plasma generation region in fluid flow.