• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.292-301
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• 1994

The resultant cutting force during machining with a worn tool is viewed as a decomposition of the cutting force into a cutting force component related to chip removal from the workpiece and into a component dependent on the contact force between the tool flank's wear land and the workpiece. The shear line method, in which the cutting force is considered proportional to the length of the shear line, is used to calculate the cutting force component for the removal of the chip, while the elastic effect of the workmaterial on the tool is taken into consideration to analyze the effect of tool flank wear. The predicted resultant cutting force, expressed as the sum of both components, is compared to experimental data obtained during wave-on-wave cutting.

• Journal of the Korean GEO-environmental Society
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• v.12 no.7
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• pp.67-76
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• 2011

In this present study, to evaluate a behavior characteristics of the sea dyke coastal covering stone by sea waves. sea waves act on coastal structures as an impact load. During impact loading, erosion and bluff slumping occur in the coastal structures. Also, the covering stone are worn down by wave impact. The sea dyke has been used near coastal region for protection of infra-structure since 1970s in Korea. The sea dyke consist of dredged sand and covering stone mainly. The damage type of covering stone has been reported since 1970s. However, the interaction of impact load by sea wave with the covering stone has not been investigated yet properly. Mainly damage type of covering stone is an abrasion. But the study of covering stone abrasion is not sufficient. Hence, In this study, it was analyzed the interaction of impact load by sea wave and the covering stone during sea wave action on coastal structures. In order to analyze the behavior characteristics of coastal covering stone considering the magnitude and period of impact loading and to evaluate the displacement increment of covering stone during impact load, numerical analysis was carried out considering impact loading by sea wave.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.109-115
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• 2013

In this study, a variable swash plate compressor has been used in a vehicle to improve its fuel efficiency. To manufacture the swash plate, either SCM 435 or UNS C67300 was used. The effects of using different materials for the structural reliability of compressor have been investigated. Static analysis was carried out on swash plate A/C compressor by using commercial software ANSYS 13.0v. The results showed that the Max. stress occurred on the swash plate made of UNS C67300 was lower than that made of SCM435, which indicated that UNS C67300 is more suitable for producing the safe swash plate.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.119-126
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• 2003

This paper presents a methodology for constructing a surgical simulation environment for the replacement of artificial knee join using CT image data. We provide a user interface of preoperative planning system for performing complex 3-D spatial manipulation and reasoning tasks. Simple manipulation of joystick and mouse has been proved to be both intuitive and accurate for the fitness and the wear expect of joint. The proposed methodology are useful for future virtual medical system where all the components of visualization, automated model generation, and surgical simulation are integrated.

• Journal of the Korean Magnetics Society
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• v.2 no.1
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• pp.69-74
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• 1992

This paper describes the energy and speed characteristics of an induction coil-gun. The coil-gun has some merits that it can be easily installed and repeatedly used many times, it does not damage mechanically in the course of launch and the force exerted on the projectile is distributed uniformly. An equivalent circuit is employed for modeling the coil-gun. The circuit equations and equation of motion are then derived based on the equivalent circuit. These equations are solved numerically by using Runge-Kutta method. Finally the energy transfer ratios are obtained according to the variations of the resonant frequency of driving circuit and charging voltage of capacitors. The muzzle velocities of projectile are also obtained according to the variations of electrical conductivity and initial position of projectile, firing angle of driving circuit, charging voltage of capacitor and resistance of driving coil, respectively.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.10
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• pp.973-978
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• 2010

In this paper, we studied the shimmy phenomena of an aircraft nose landing gear considering free-play. Shimmy is a self-excited vibration in lateral and torsional directions of a landing gear during either the take-off or landing. This phenomena is caused by a couple of conditions such as low torsional stiffness of the strut, friction and free-play in the gear, wheel imbalance, or worn parts, and it may make an aircraft unstable. Free-play non-linearity is linearized by the described function for a stability analysis in a frequency domain, and time marching is performed using the fourth-order Runge-Kutta method. We performed the numerical simulation of the nose landing gear shimmy and investigated its linear and nonlinear characteristics. From the numerical results, we found limit-cycle-oscillations at the speed under linear shimmy speed for the case considering free-play and it can be concluded that the shimmy stability can be decreased by free-play.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.605-611
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• 2011

Shimmy is a self-excited vibration in lateral and torsional directions of a landing gear during either the take-off or landing. It is caused by a couple of conditions such as a low torsional stiffness of the strut, a free-play in the landing gear, a wheel imbalance, or worn parts, and it may make the aircraft unstable. This study was performed for an analysis of the shimmy stability on a small aircraft. A nose landing gear was modeled as a linear system and characterized by state-equations which were used to analyze the stability both in the frequency and time-domain for predicting whether the shimmy occurs and investigating a good design range of the important parameters. The root-locus method and the 4th Runge-Kutta method were used for each analysis. Because the present system has a simple mechanism using a friction to reinforce the stability, the friction, a non-linear factor, was linearized by a describing function and considered in the analysis and observed the result of the instability reduction.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.79-84
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• 2007

In this paper, the finite element analysis of a valve screw for a LPG cylinder has been presented on the leakage safety and strength one, which are computed and investigated by a contact normal stress and von Mises stress between a female screw of a valve and a male screw of a neck ring in a LPG bombe. The LP gas charging pressure of a LPG bombe is $8{\sim}9kg/cm^2$, which is pressurized to the screw sealing contact areas between a valve and a LP gas cylinder. The peak failures of the screw tooth height due to a scratch wear and chipping loss of the contact area may decrease screw tooth strength and increase a leakage of a LP gas. These are strongly affect to the contact normal and von Mises stresses of the valve screws. The FEM computed results show that the tooth height loss due to a wear and chipping failure of the screw peak does not affect to the LP gas leak and strength of a valve screw theoretically. But if the tooth wear of the screw height of a brass valve overpasses the critical strength safety of the valve, the valve screw may be failed in fastening the valve and a LP gas bombe suddenly.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.179-184
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• 2017

The cage of a tapered roller bearing keeps the gap between the rollers, which prevents friction, wear and suppresses heating. The material of the cage is changing from metal to plastic for lightening the weight. If the cage is severely deformed due to resonance, the roller may not be able to roll and even get off the cage. In this paper, the dynamic characteristics of the cage is analyzed according to the cage material. Under the assumption that a train runs at the highest speed, frequency harmonics of that speed is calculated, and the comparative analysis is carried out in order to select the optimum thickness of the cage, which is easy to change among the cage design variables for avoiding the resonance.

• Journal of computational fluids engineering
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• v.6 no.4
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• pp.26-34
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• 2001

The flow past a circular cylinder forced to vibrate transversely is numerically simulated by solving the two-dimensional Navier-Stokes equations modified by the vibration velocity of a circular cylinder at a Reynolds number of 164. The higher-order finite difference scheme is employed for the spatial discretization along with the second order Adams-Bashforth and the first order backward-Euler time integration. The calculated cylinder vibration frequency is between 0.60 and 1.30 times of the natural vortex-shedding frequency. The calculated oscillation amplitude extends to 25% of the cylinder diameter and in the case of the lock-in region it is 60%. It is made clear that the cylinder oscillation has influence on the wake pattern, the time histories of the drag and lift forces, power spectral density and phase diagrams, etc. It is found that these results include both the periodic (lock-in) and the quasi-periodic (non-lock-in) state. The vortex shedding frequency equals the driving frequency in the lock-in region but is independent in the non-lock-in region. The mean drag and the maximum lift coefficient increase with the increase of the forcing amplitude in the lock-in state. The lock-in boundaries are also established from the present direct numerical simulation.