• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.875-882
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• 2011

In this paper, the finite element analysis model of the mult-axial wheel durability test configuration is created using SAMCEF. Mooney-Rivlin 2nd model is applied to the tire model, and the variation of the air pressure inside the tire is considered. Vertical load, lateral load and camber angle are applied to the simulation model. The tire rotates because of the friction contact with a drum, and reaches its maximum speed of 60 km/h. The dynamics stress results of the simulation and experiment are compared, and the reliability of the simulation model is verified.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.78-84
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• 1997

Friction welding technique was studied to weld the turbine wheel and shaft of a turbocharger. The welding parameters were selected to investigate the effects of variables on welding quality of Inconel 713C and SCM 440. Experimental results showed that the turbine wheel and shaft could be successfully welded by friction welding. The heat affected zone was identified to be 2 mm from the weld seam. After welding, the hardness profile was found to have sudden increase and decrease for inconel 713C and SCM 440 respectively. Tensile strength of welded specimens was higher than the required strength for all of the studied welding parameters. The central portion of fracture surfaces by bending had no defects such as crack.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.192-201
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• 1997

The feedback control scheme of the pressure control system of the rear wheel steering gear which has relatively large volume and sprung load was built up in order to improve th response characteristic of the system. The control algorithm chosen was a feedback compensator joined by a feedfoward compensator and the model matching method was used in the process of control system design. The structures and properties of the reference models were inspected and the parameters of the controller were decided. The improvement of the response characteristic of the pressure control valve by means of the feedback control is affirmed. Particularly, when the order of the system model is higher than the 2nd order, the effectiveness of the feedback control on the improvement of the response characteristic of the valve is distinct. And the convenience of the model matching method is the process of control system design is confirmed as well.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.2
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• pp.86-94
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• 1995

For a driving vehicle, a self-excited vibration of a pair of steerable wheels about their steering axis accompanied by tramp is called shimmy. Shimmy is caused by the coupling effects of the complicated actions of wheel and tire and the tramp motion of front wheel axle. Because front axle is no longer used on passenger cars shimmy occurring is not considerable. But in commercial vehicles using front wheel axle suspension system shimmy should be considered in design process. In this paper, the model closed to a practical vehicle was developed to analyze the shimmy of a commercial vehicle, and the effects of various design parameters to shimmy were observed by dynamic simulation with multibody dynamics program, DADS. The validity of developed model and analysis results were verified by practical vehicle experiments.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.2
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• pp.83-88
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• 2005

This study investigates the air leakage and heat transfer characteristics of a commercially available rotary-type air-to-air heat exchanger with a fiber polyester matrix. Crossover leakage between the exhaust and supply air is measured using a tracer gas method for various ventilation rates and rotational speeds of the wheel. A correlation equation for the leakage is obtained by summing up pressure leakage and carryover leakage. The pressure leakage is observed to be a function of ventilation rate only, and the carryover leakage is found to be a linear function of wheel speed. The real efficiency of the heat exchanger can be obtained from its apparent efficiency by taking into account the leakage ratio. The heat recovery efficiency decreases, as the ventilation rate increases. As the wheel speed increases, however, the efficiency increases initially but reaches a constant value for the speeds over 10rpm.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.57.3-57.3
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• 2019

Space applications of the motion have been served with DC motors for decades. But their functionality with a gearbox and lubricants and their weights are always an issue for its application. A piezo-motor has an advantage on the direct driving with higher accuracy, smaller size, and no-EMI. We use the piezo-motor to rotate a filter wheel directly in a balloon-borne coronagraph launched on September 2019. The piezo-motor works well in a temperature range from -10 to 40 Celsius with high reliability and high positioning / tilt accuracy (~0.1degree) with a photo-encoder. We verify its functionality for 7 days. In this talk, we report the design, test processes of the filter wheel including its balloon flight result.

• Journal of the Korea Safety Management & Science
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• v.15 no.4
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• pp.123-129
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• 2013

Among various manual materials handling tasks, pushing/pulling was known to be one of the risk factors for the low back and shoulder musculoskeletal disorders (MSDs). This study was conducted to find out an optimal solution set of the handle height and distance for 4-wheel cart with two vertical handles. Ten male college students participated in the pushing force measurement experiment. The face-centered cube design, one of the central composite designs, was applied for the experiment, and the isometric voluntary pushing force was measured in 9 treatment conditions. The second order response surface model was predicted by using the pushing strength as a response variable, and the handle height and distance as independent factors. According to the 2nd order response model, the handle height and distance showed nonlinear relationship with the isometric pushing strength. To maximize the 2nd order response model (pushing force), the handle height and distance were optimized. The optimal handle height was 'xyphoid process height - stature', and the optimal handle distance was '$1.25{\times}shoulder$ width'. When calculated using the anthropometric data of the subjects of this study, the optimal handle height was $115.4{\pm}3.4$ cm, slightly higher than the elbow height, and the handle distance was $52.9{\pm}2.3$ cm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.1049-1052
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• 1997

The pupose of this study on the surface finishing is to examine the performance of brushing as a means of reducing the surface roughness of the precision theaded shafts in ball screw assemblies. Ball screws provide superior performance compared to other types of screw feeds in terms of static and dynamic rolling resistance,backlash,and wear characteristics. The Reduction of the surface roughness of the lead shaft in ball screw assembiles is essential for precision movement,high speed/low noise tracel, and for low wear/long life. To reduce machine dependent errors that would influence the surface roughness compared with other lapping or polishing techniques,experiments will be performed using special wire brushes to polish precision ground shafts. The best results were obtained using the Al /sab 2/O /sab3/ brushes, with the Al /sab 2/O /sab3/ #500 grit brush producing a surface finish of approximately 0.7 .mu.m, and the Al /sab 2/O /sab3/ #600 grit producing a surface finish of approximately 0.8 .mu.m. Both of these results were produced at the highest wheel polishing speed of 3520 rpm. The SiC #500 brush produced a surface roughness of approximately 1 .mu.m at 3520 rpm.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.849-852
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• 2008

In the wheel tracking test to evaluate abrasion resistance for concrete surface coating materials applied parking lot, weight of the wheel, test temperature, scattered sand amount, wheel speed, etc. various test condition is used for reliable evaluating the abrasion resistance performance of surface coating materials and the results depends on the test condition. In this paper, we carried experimental study as following on abrasion resistance with 2kinds of different environmental conditions. - Commons : real car tire with 300kg of load, 5km/h of speed, 80,000 cycle. - Control A : no other deterioration condition - Control B : scattering 1.0g of sand per every 30rounds from 1m height.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1115-1118
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• 2015

Two wheel type electric vehicles driving with the electric motors for guard are used increasingly at the airport and harbor place to move between narrow indoors. This type two wheel electric vehicles are powerd by batteries and using the steering control apparatus including multi sensors and handle operating device for forward and backward, rotating moving. At this research, we design sensor interfacing electronic control system use only the center of foot balance without the handle type steering apparatus. This design is for safety of drivers at one's cornering.