• 한국생산제조학회지
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• 제21권6호
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• pp.968-975
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• 2012

ABS(Anti-skid Brake System) had been developed on purpose of most effect at breaking in limited runway. An aircraft has a large amount of kinetic energy on landing. When the brakes are applied, the kinetic energy of the aircraft is dissipated as heat energy in the brake disks between the tire and the ground. The optimum value of the slip during braking is the value at the maximum coefficient of friction. An anti-skid system should maintain the brake torque at a level corresponding to this optimum value of slip. This system is electric control system for brake control valve at effective control to prevent slip and wheel speed or speed ratio. In this study we measured the thickness of the carbon disk before and after to find its wear and it shows that carbon disk brake has higher stiffness and strength than metal disk at high temperature. In addition, thermal structural stability and appropriate frictional coefficient of the carbon disk brake prove its possible substitution of metal disk brake.

• 한국기계가공학회지
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• 제20권10호
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• pp.80-87
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• 2021

Our study introduces an improved modular agricultural platform to provide convenience to agricultural workers. We upgrade the platform design in three parts, namely, by adding a 458 pattern tire, electricity control, and four-wheel steering function, to improve the platform performance. Results showed that the upgrades enhanced the platform performance and reduced its overall weight as compared with the existing platform. To demonstrate the performance of our improved platform, we conducted five types of experiments with respect to the climbing angle, variable width, attitude control, speed, and obstacle passing.

• 한국기계가공학회지
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• 제18권4호
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• pp.10-15
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• 2019

In this paper, we report a robust steering control using time delay control for the vehicle dynamics variation due to tire/road contact condition variation, the lateral disturbance force due to the side wind, and the yaw disturbance moment due to the difference between the left and right tires' pneumatic pressure. We controlled the side slip and yaw damping compensation for rapid steering at the high velocity of the vehicle. Based on the developed control, the driver can only consider the desired path without concerning on the vehicle dynamics variation, disturbances, and undesired side slip and yaw oscillations. Simulation results show that robustness from the vehicle dynamics variation and disturbances was achieved by using the developed time delay control. We evaluated the side slip and yaw damping compensation capability for the rapid steering at the high velocity of the vehicle in the cases of three control methods.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.304-309
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• 1997

Elastic elements, at first, were extensively used in suspensions as vibration isolators at joints. Nowadays they are used to improve stability and handling. The design of these elements has become a very important matter since the loading condition of the mechanism gives a mew suspension geometry without any modification. This paper presents an analysis of forces and moments of joints with elastic elements in the McPherson suspension mechanism to evaluate accurately the elastic deformation using the displacement matrix method in conjunction with the equilibrium equations. First the suspension is modeled as a multi-loop spatial rigid-body guidance mechanism which has elastic elements at the hardpoints of the suspension. Then a method and design euqations are developed to analyze the suspension characteristics by the various tire load. Also the displacement matrices and constraint equations for links are appllied to determine the sensitivity of the suspension mechanism. Finally this approach may conduct a realistic design of suspension mechanisms with elastic elements to improve the performance of the automobile under various driving conditions.

• International Journal of Automotive Technology
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• 제6권6호
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• pp.625-633
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• 2005

Vehicle drift was reduced using statistical six sigma tools. The study was performed through four steps: M (measure), A (analyze), I (improve), and C (control). Step M measured the main factors which were derived from a fishbone diagram. The measurement system capabilities were analyzed and improved before measurement. Step A analyzed critical problems by examining the process capability and control chart derived from the measured values. Step I analyzed the influence of the main factors on vehicle drift using DOE (design of experiment) to derive the CTQ (critical to quality). The tire conicity and toe angle difference proved to be CTQ. This information enabled the manufacturing process related with the CTQ to be improved. The respective toe angle tolerance for the adjustment process was obtained using the Monte Carlo simulation. Step C verified and controlled the improved results through hypothesis testing and Monte Carlo simulation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.305-308
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• 2002

The mechanics, electronics and manufacturing technology have been developed rapidly. Nowadays vehicle stability becomes more and more important then ABS (Anti-lo7k Brake System), ASR (Anti-Slip Regulator), TCS, (Traction Control System), ESP (Electronic Stability Program), and VDC (Vehicle Dynamic Control) which actively control the vehicle stability actively has been improved. In this study, instead of automatic transmission, CVT (Continuously Variable Transmission) is used because of the continuously gear ratio changes. It can effectively transfer the torque from engine to tire more than other gear transmission. The modeling is simplified assuming that there are no resistance parameters.

• Industrial Engineering and Management Systems
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• 제8권3호
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• pp.162-170
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• 2009

This paper deals with a closed-loop remanufacturing system with one manufacturer and one remanufacturer. The manufacturer sells new products bearing the 'Extended Producer Responsibility (EPR).' It is assumed that the manufacturer's collection rate of used products depends only on the buy-back cost, while that of the remanufacturer depends on the minimum allowed quality level of used products in addition to the buy-back cost. Through the development of mathematical models with the objective function of maximizing profit, we study an efficient operation policy of each party. The decision variables are the unit selling price of new products and remanufactured products, the unit buy-back cost of the used products of the manufacturer and remanufacturer, and the minimum allowed quality level. The validity of the model is examined through numerical examples and sensitivity analysis.

• 한국공작기계학회논문집
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• 제14권3호
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• pp.116-121
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• 2005

The objective of this paper is to compare the site-to-site variability of ISO 10844 pass by the noise test sites. In order to investigate the site-to-site variance of test surfaces, European commercial tires are tested at seven different test sites. Three Korea test sites and four Europe test sites are selected. The pass by noise test is done according to a 2001/43/EC regulation. Although the ISO surface has a very specific track composition, it does not reduce the variation of pass by noise measurements over the surface of test sites. This paper shows that the test results of pass by noise level are different depending on the test sites. The correlation obtained in this work is able to predict the pass by noise level for certain test site using the data measured from another test site. The prediction value is range with an error within 1dB(A).

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.330-335
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• 1993

This paper presents an efficient solution for a class of forbidden state problems by introducing a cyclic timed controlled marked graphs (TCMG's), a special class of timed controlled Petri nets (TCPN's) as a model of a class of discrete event systems (DES's). The state feedback control is synthesized, which is maximally permissive while guaranteeing the forbidden states will be avoided. The practical applications or tire theoretical results for an automated guided vehicle (ACV) coordination problem in a flexible manufacturing facility is illustrated.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.251-254
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• 2003

In recent years, shearogrpahy has significantly improved capabilities In the areas of unbend and separation detection in tires. Although shearography has many advantages fur qualitative evaluation, the technique remains the problem of quantitative analysis of inside defects, because shearography needs several effective factors including the amount of shearing, shearine direction and induced load, which exist as barrier for the quantitative analysis of inside defects. Since the factors are highly dependent on inspectors skill and also affect the in-situ workability. The factors were optimized and the size of cracks inside of pipeline and tire has been quantitatively determined.