• Journal of the Korean Society for Precision Engineering
• /
• v.1 no.1
• /
• pp.50-58
• /
• 1984

In the present paper are calculated and compared the stresses on the normal tools and the restricted tools which have three various rake angles by Least Square Method. The results obtained are summerized as follows. The tool displacement at rake angle .alpha. = 12 .deg. and .alpha. = 0 .deg. is positive value in the principal cutting direction and negative value in the feed direction. At rake angle .alpha. = -12 .deg. the displacement is negative value in both of directions. The principal stress of the restricted and normal tool is maximum at the tip of the tool, the shear stress is maximum after a certain distance from the tip. The result of FEM and P.E method shows that in the range of rapid decreasing of normal stress of the tool edge, the shear stress is maintaining a certain value. This is due to the friction characteristic of the chip.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.1469-1472
• /
• 2006

This paper presents experimental analysis of a friction-driven wheel responsible for generating wheel squeal. Squeal noise generating mechanism has been examined under the laboratory condition. Model rig of the rail and the wheel are made and influential parameters to squeal noise e. g. frictional force, normal force between the rail and the wheel, creep speed of the wheel have been measured and calculated. Negative damping characteristic curve are calculated currently. Necessary relating computational analysis has been carried on also.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.1142-1148
• /
• 2006

The floating ring seal which is used in the high pressure turbo pump is frequently used in the oxidizer pump and the fuel pump of the turbo pump of the liquid propulsion rocket, because it is able to minimize clearance to decrease the leakage flow rate. But, floating ring seal has a tendency to increase the force which caused instability of system as the eccentricity ratio increases. In this paper, we devised design of floating ring seal which decrease contact area between floating and supporting ring. Modified floating ring seal has a tendency to decrease the eccentricity ratio compare with original floating ring seal. The whirl frequency ratio which is able to distinguish stability of system decrease compare with original floating ring seal

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.12 no.2
• /
• pp.17-28
• /
• 2004

In unmanned aerial vehicle (UAV), the high temperature results from friction with the air, combustion of fuel and combustion gas of a nozzle etc. It causes serious problems in the UAV structure. The characteristic analysis of heat resistant metal and ceramic materials and creep analysis for the functionally graded material (FGM) is presented in this paper. FGM is composed of two constituent materials that are mixed up according to the specific volume fraction distribution in order to withstand high heat condition. In addition, the creep behavior of FGM applied in duct structure of an engine is analyzed.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.1068-1075
• /
• 2009

The Soil-nailing installed to the slope or the vertical excavation surface shows reinforce effect using frictional resistance between ground and grout. This friction is showed the more the shape of grout is rough, the more efficient.. This study is about the characteristic behavior of Soil-nailing has partial extension grout made artificially control. In this study, we refer to the new boring machine that can make partially extended grout and perform 3D analysis between of the partial extended grout and the general grout of a cylinder shape using the finite element method for comparing.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.3
• /
• pp.105-109
• /
• 2001

In this paper, the windmill type ultrasonic motors with 11.35 mm diameter, 2.87 mm thickness of metal endcap and 1.47 g weight were fabricated. Effects of slots and thickness on torque characteristic in the windmill type ultrasonic motor were investigated, when stator's slots were changed from 4, 6, 8 and thickness 0.15 mm, respectively. Specially designed metal endcaps with windmill shaped cutting can provide longitudinal and torsional displacements simultaneously as the ceramic disk vibrates radically. The windmill type ultrasonic motor has only three components: a stator element with windmill shape slotted metal endcap, a rotor and bearing. Ultrasonic motor stimulated to ultrasonic oscillations by piezoelectrics to drive a rotor via friction contact. The ultrasonic motor fabricated here was the windmill type ultrasonic motor operated by single-phase AC source. Bidirectional revolution using single-phase high frequency for driving the ultrasonic motor was presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.08a
• /
• pp.23-26
• /
• 2003

An ultrasonic motor is a motor which uses vibration -a type of elastic vibration- to obtain a driving force, which then drives the motor using friction. In this paper, mode conversion type - single resonance mode ultrasonic rotary motor that use langevin type ultrasonic vibrator was studied. This model was proposed for the first time by Japanese Kumada in 1985. In this study, finite element analysis (FEA) of a stator and bidirectional driving characteristic of a rotor was newly obtained. The amplitude and phase of displacement and elliptical trajectory of beam was confirmed by FEA The fabricated motor was operated to clockwise and counterclockwise in 40.8 [kHz] and 44.2 [kHz] respectively. But bidirectional driving characteristics did not coincide each other.

• Nuclear Engineering and Technology
• /
• v.30 no.4
• /
• pp.328-341
• /
• 1998

This paper presents in detail the hydraulic characteristic measurements using LDV(Laser Doppler Velocimetry) in subchannels of a HANARO, KAERI research reactor, fuel bundle. The fuel bundle consists of 18 axially finned rods with 3 spacer grids and has a cylindrical configuration. Axial velocity and turbulent intensity were measured. The effects of the spacer grids on the turbulent flow were investigated using the experimental results. Pressure drops for each component of the fuel bundle were measured, and the friction factors of the fuel bundle and the loss coefficients for the spacer grids were estimated from the measured pressure drops. The turbulent thermal mixing phenomena were discussed.

• Journal of the Semiconductor & Display Technology
• /
• v.6 no.1 s.18
• /
• pp.31-36
• /
• 2007

Effect of coulomb friction and backlash on the single loop position control has been studied for the precision position control. We have showed the limit cycle on the single loop system which used a ball screw that had the backlash. Also, we have made an inner loop with a classical velocity and torque controller which was forcing the current of d axis to be zero by using a permanent-magnet synchronous motor and composed the outer loop with linear encoder for sensing a position of the loader. Also, we have used least squares fit(LSF) observer for reducing noise when we got velocity from position outputs. We have shown a good result by using the dual loop through simulation and experiment.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2000.10a
• /
• pp.484-489
• /
• 2000

This study was performed to examine the characteristic of creep behavior by reinforced clayey soil. So, it was carried out measurement of compressive strain and poisson's ratio by the reinforced soil mixtures. At each specimen was made by added calcium carbonate and 19mm length monofilaments into soil at designated ratio, and it was measured during the age of 30 days right after manufacturing the specimens. Because monofilaments controled increase of friction and dry shrinkage of soil into soil, compressive strain of monfilments reinforced soil with mixing rate of 0.3% is low value. And Because void was formed by compressive, vertical strain and horizontal strain of calcium carbonate reinforced soil with rate of 9% is high value.