• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.174.4-174
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• 2001

Vehicle stability control system can enhance the vehicle stability and handling in the emergency situations through the control of traction and braking forces at the individual wheels. To achieve the desired performance, the wheel slip controller manages the hydraulic braking system to generate the desired braking force at each wheel. In this study, we propose the wheel slip controller for the generation of the braking forces based on multiple sliding mode control theory with the pulse width modulation. The proposed controller follows to the slip ratio and the brake pressure the desired ones so that the vehicle stability controller can Intervene braking force at each wheel. We show the validity and usefulness of the proposed controller through computer simulations.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.56-61
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• 1986

Rotor dynamic response of pumps is greatly influenced by the nature of the hydraulic forces arising from wearing seal, balance drum and impeller, etc.. Therefore, rotor dynamic analysis should be conducted during the design stage in order to aleviate some of the vibrational problems which might occur during the operational life of pumps. Previsousely, the authors have proposed the method to obtain the dynamic seal coefficients of the annular plain seal, convergent and divergent tapered seals, parallel grooved seal, spiral grooved seal and annular stepped seal. On the basis of these results, this paper presents the investigated effect of seals on the stability behavior of a centrifugal pump. The results show the effects of seal geometry, pressure difference, clearance, length/diameter ratio, on stability behavior.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.43-49
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• 1986

The stability behavior of the cantilever beam carrying several masses and subjected to a follower force at its free end is investigated. The effects of the location and the mass ratio of the concentrated masses on the stability of the system are discussed. An optimal location of the concentrated mass is determined to give maximum critical follower force. Discontinuities of the flutter load are observed for the system with more than two concentrated masses.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.811-818
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• 2001

The wave characteristics for a non-reacting high-speed liquid jet were investigated using a linear stability theory. In this study, 2-D incompressible viscid momentum equation for a liquid jet was considered, and the effects of injection parameters, such as Weber number, Reynolds number, and density ratio, on the wave characteristics were investigated. With the wavelength obtained from the stability analysis, the atomization model was suggested. The droplet sizes after breakup were determined by the wavelengths of fast growing waves, and the mass of the shed droplets was determined by the breakup time derived by ORouke et al. It was found that in comparison with measurements of diesel fuel spray, the results of calculation had a similar trend of the decrease of overall SMD with the increase of Reynolds number.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1161-1169
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• 2007

In this paper, the dynamic stability of a rotating cantilever pipe conveying fluid with a crack is investigated by the numerical method. That is, the influence of the rotating angular velocity, mass ratio and crack severity on the critical flow velocity for flutter instability of system are studied. The equations of motion of rotating cantilever pipe are derived by using extended Hamilton's principle. The crack section of pipe is represented by a local flexibility matrix connecting two undamaged pipe segments. The crack is assumed to be in the first mode of fracture and always opened during the vibrations. Generally, the critical flow velocity for flutter is proportional to the rotating angular velocity of a pipe. Also, the critical flow velocity and stability maps of the rotating pipe system for the variation each parameter are obtained.

• Fashion & Textile Research Journal
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• v.4 no.1
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• pp.86-91
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• 2002

To estimate dispersion stability of particles, suspending power and particle size were examined as functions of pHs, surfactants, electrolytes and ionic strengths using ${\alpha}-Fe_2O_3$ particle as the model of particulate soil. Suspending power and particle size were determined by UV-Vis spectrumeter and by light scattering using the polarization ratio method, respectively. The suspending power was relatively high with polyanion electrolytes and was low with neutral salts. The suspending power was biphasis, minimum pH 6~7, and the effect of surfactant on the suspending power was insignificant. Generally suspending power increased with decreasing the particle size governed aggregation of dispersed particles regardless of solution conditions. Hence the suspending power was inversely related to the particle size.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.10
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• pp.976-982
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• 2007

In this paper the vibration system is consisted of a rotating cantilever pipe conveying fluid and tip mass. The equation of motion is derived by using the Lagrange's equation. The system of pipe conveying fluid becomes unstable by flutter. Therefore, the influence of a rotating angular velocity, mass ratio, the velocity of fluid flow and tip mass on the stability of a cantilever pipe by the numerical method are studied. The critical flow velocity for flutter is proportional to the angular velocity and tip mass of the cantilever pipe. Also, the critical flow velocity and stability maps of the pipe system are obtained by changing the mass ratios.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.3
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• pp.6-14
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• 2007

In this research, vibration reduction and aeroelastic stability of a composite hingeless rotor hub flexure with viscoelastic constrained layer damping treatment(CLDT) were investigated. The composite flexures with viscoelastic CLDT were applied to hingeless rotor system to improve the in-plane stability of the lead-lag motion causing resonance. The modal test was performed and dynamic properties(natural frequency and loss factor) were acquired. Also, complex eigenvalue analysis(SOLlO7) in the NASTRAN structural analysis module was performed and compared with results of the modal test. To insure aeroelastic stability, damping ratio analyses of the hingeless rotor system with CLDT were accomplished at hovering condition due to collective pitch angle changes. Satisfactory results of increasing structural damping and stability were obtained.

• Structural Engineering and Mechanics
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• v.4 no.5
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• pp.485-496
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• 1996

This paper describes a numerical and experimental study on the stability and failure behaviour of rectangular symmetric laminated composite plates. The plates are simply supported along the unloaded edges and clamped along the loaded ends, and they are subjected to uniaxial in-plane compression. The finite element method was employed for the theoretical study. The study examines the effect of the plate's stacking sequence and aspect ratio on the stability and failure response of rectangular symmetric laminated carbon fibre reinforced plastics composite plates. The study also includes the effect of the unloaded edge support conditions on the postbuckling response and failure of the plates. Extensive experimental investigation were also carried out to supplement the finite element study. A comprehensive comparison between theory and experimental data are presented and discussed in this contribution.

• Journal of Pharmaceutical Investigation
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• v.20 no.3
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• pp.145-152
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• 1990

Zirconium pyrithione complex was prepared by reaction of sodium-pyrithione solution and zirconyl chloride solution. The physico-chemical properties of the complex was examined by means of IR, XRD, DSC and NMR. And the stability of Zr-complex was investigated on the basis of accelerated stability analysis under conditions of temp. elevation, UV radiation and pH dependence. The result indicates that the ratio of the ligand to metal in Zr-pyrithione complex was determined 4:1, and its stability constant was $4.643{\times}10^4$. The rate order of decomposition of the complex was apparent first-order reaction of which rate constant and the decomposition rate was not only accelerated by effect of heat and UV radiation but was catalyzed by specific acid-base catalysis considered the pH dependence for the hydrolysis of the complex and the suspension was most stable over the range pH 4-8 indicating that solvent catalysis is the primary made of reaction in this region.