• The Journal of Engineering Geology
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• v.30 no.3
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• pp.289-302
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• 2020

To determine the shallow subsurface structure and sliding surface of land creeping in 2016 at Hadong-gun, Gyeongsangnam-do, geophysical surveys (electric resistivity, and refraction seismic methods, borehole televiewer) and slope stability analysis were conducted. The subsurface structure delineated with borehole lithologies and seismic velocity structures provided the information that the sediment layer on the top of the slope was rather as thick as 20 m and the underlying weathered rock (anorthosite) was thinner than 1 m. Based on the tension cracks observed during the geological mapping, televiewer scanning was performed at the borehole BH-2 and detected the intensive fracture zones at the ground-water level, associated with the slip weak zones mapped in dipole-dipole electrical resistivity section. Downslope sliding and slightly upward pushing at the apex of high resistive bedrock explains the curved slip plane of the land creeping. Such a convex structure might play a role of natural toe abutment for preventing the downward development of slip weak zones. In slope stability analysis, the safety factors of the slip weak zone are calculated with varying the groundwater levels for dry and rainy seasons and the downslope is founded to be unstable with safety factor of 0.89 due to fully saturated material in rainy season.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.261-264
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• 1997

A contactless eddy current type braking system is developed to take advantages of the recent brake system which uses hydraulic force can show high efficiency in a certain velocity region, but not in a high velocity region, and has initial response delay time and pressure build-up time which make stopping distance longer. These are the limits of mechanical brake system of a contact type, which makes a concept brake system required. So, in this paper, the contactless brake system .of a inductive current type is chosen instead of hydraulic brake system. This brake system can be used almost forever for being no wear and contributed to lightening weight of a vehicle. Besides, the contactless brake system can be used as that of electric or solar car with anti-lock brake system. The analysis of induced electromotive force and braking torque obtained with theoretical approximate model, the design of a braking system and a nonlinear controller, and the results of simulation of the ABS, experiment are included.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.60-63
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• 2000

In this study, efficient force reflection algorithm is developed for the Haptic Display by using a proxy concept and friction model. When there are not any contacted obstacles the proxy is following human operator's command trajectory in the 3D virtual space. But when the operator's command trajectory is locating inside of the object, the proxy is constrained by the surface of the object. Here only with the information of the proxy position and operator's command trajectory at every time step, we can calculate the reflection force and its orientation. To display the friction force between two virtual stiff material which are sliding against each other, modified Karnopp's friction model is used. In the friction model, a damping term and a Stribeck effect term are included to display the relative velocity effect and stick-slip effect at the very low relative velocity region respectively.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.90.5-90
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• 2002

In this research, we are trying to develop an automatic sorting system, which is mostly affected by frictional forces between a veneer and plank. So we will make a suitable dynamic model and mechanism to control the velocity feedback. We will suggest stick-slip motion model which can predict the stability behavior of this system. The control system has a feedback loop, in which the following operations are included. A kind of sensor can get the velocity of the mass to adhesive veneer. The output of result signal should be passed to a filter, then to a phase shifter, which applies an adjustable phase-shift, to a variable-gain amplifier. A shaker will be attached to the mass, which ex...

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.331.1-331
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• 2002

Four degrees of freedom mathematical model is presented to describe the fundamental mechanisms of the disc brake squeal noise. A contact parameter is introduced to describe the coupling between the in-plane and the out-of-plane motions. The friction coeficient including "relative velocity" and ′normal force" can be generally formulated as the form of multiplication with polynominal parameters(${\beta}$, ${\gamma}$). (omitted)

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.107-113
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• 2002

To monitor the torque of an induction motor using current, rotating speed has been measured and used to calculate the slip angular velocity. Additional sensor, however, can cause extra expense and trouble. In this paper, a new algorithm is proposed to monitor the torque of vector controlled induction motor without any speed measuring sensor. Only stator current is measured to estimate the magnetizing current which is used to calculate flux linkage, rotor velocity and motor torque. Graphical programming is used to implement the suggested algorithm and to monitor the torque of an induction motor in real time. To solve the fluctuation problem of estimated torque caused from instantly varying rotating speed of an induction motor, the rotating speed is reconstructed based on the measured current signals. From several experiments, the proposed method shows a good estimation of the motor torque under the normal rotational speed.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1524-1529
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• 2003

In this paper deals with a unique method for measuring vehicle states such as body sideslip angle and tire sideslip angle using GPS velocity information in conjunction with other sensors. A method for integrating Inertial Navigation System (INS) sensors with GPS measurements to provide higher update rate estimates of the vehicle states is presented, and the method can be used to estimate the tire cornering stiffness. The experimental results for the GPS velocity-based sideslip angle measurement and cornering stiffness estimates are compared with the theoretical predictions. From the experimental results, it can be concluded that the proposed method has an advantage for future implementation in a vehicle safety system.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.110-110
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• 2000

In this paper, an antilock brake system (ABS) for commercial vehicles is studied by considering the design of a fuzzy Logic controller with pulse width modulation (PWM). PWM method is used for generating solenoid valve inputs in order to cope with the chattering problem caused by the conventional on/off control The sliding mode observer is designed to estimate the vehicle longitudinal velocity and it is used to calculate the wheel slip ratio. The effectiveness of the proposed control algorithm was validated by simulations performed with a nonlinear 14-DOF vehicle model including the dynamics of the brakes.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.364-373
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• 2001

This paper describes the variation of lubricant's temperature effects on elastohydrodynamic lubrication. The Newton-Raphson technique was used to solve the simultaneous system of Reynolds and elasticity equations. To show effects of lubricant's temperature, average temperature across the oil film was calculated using the energy equation. Pressure distribution, film shape, and temperature distribution were obtained for fully flooded conjunctions, and various dimensionless speed parameters while load and material parameters were held constant. Minimum film thickness were obtained for various material properties while load and velocity were held constant. It is drawn that the thermal effects have a strong influence on a minimum film thickness under high rolling velocity and slip ratio.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.671-675
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• 2005

In this paper, Development of propulsion system using IPM(Intelligent Power Module) for DC electric vehicle is proposed. Designed propulsion system is comprised of inverter stack which includes 6 IPM, BCH(Breaking Chopper) unit, FC(Filter Capacitor), Control unit. IPM can compose propulsion system simple by including gate drive circuit and protection circuit. Inverter stack is designed as a simple structure using IPM and non clamp capacitor. VVVF Inverter control is used the vector control strategy at low velocity region and slip frequency-control strategy at high velocity region. Designed propulsion system proves the performance through test and revenue service.