• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1017-1021
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• 1995

Geometric and thermal errors are responsible for major components of the errors of a computer numerically controlled turning center. The planar error of a CNC turning center are comprised of 11 geometric and thermal error components. The error synthesis model is formulated by homogeneous coordinate transformation method and expresses the effect of such error components on the planar error of a CNC turning center. In this paper, the sensitivity analysis of the model on the noises through sensing and the change of temperature is addressed. The sensitivity analysis show that the error systhesis model is robust on the noses and z planar error is much affected by the change of temperatures.

• Tribology and Lubricants
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• v.28 no.3
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• pp.112-116
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• 2012

wet-type multiple disk brakes are very important parts of turning decelerator for deck crane, because they are advanced in durability and braking power, and can be designed compactly. Thus, we designed and made wet-type multiple disk brakes of turning decelerator for deck crane to be localization of these imported all. In this study, wet multiple disk brakes were made a comparative test with the 2 types materials of friction disk by the SAE No.2 dynamometer. The friction characteristics were measured and analyzed to decide a suitable material as wear depth of friction disk and dynamic and static friction coefficient.

• Journal of Biosystems Engineering
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• v.23 no.3
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• pp.291-304
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• 1998

A control algorithm fir the unmanned vehicles was developed using image information received through a CCD camera that acquires more powerful information over the wide range of wave-length comparing with other sensors and was applied to a speed-sprayer. The algorithm consisted of straight mode for passing along with middle of two tree-rows and turning mode for changing from a row to another row. In case of turning mode, two marks of colored papers were employed to indicate turning point and to decide turning direction for various orchard situations. The method of analysis and image would be differed according to camera's tilt-angle and position that is set on the speed-sprayer. Hence, it analyzed the point of difference by making camera's up and downward tilt-angle.

• The Research Journal of the Costume Culture
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• v.12 no.3
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• pp.327-338
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• 2004

This study was attempted to check period of a fashion cycle and to suggest its main-stream and sub-stream by analyzing the fashion trends presented in Vogue Korea between 1997 and 2002. A content analysis method was used to analyze 24 volumes. The result showed that the fashion trend of 1997's was a turning point from the simplicity, which was a trend up to 1996's, to the romanticism. The fashion trends of 2002 seemed to be also a turning point from the new-romanticism which was added the hippism to the romanticism continued from 1997, to the sporticism. The result confirmed that the main-stream of fashion theme have been continued for 5 years as a regular cycle system and could be repeated. It also verified that some sub-stream which was affected by social, cultural and political situation led the fashion changes. The results of this study could be expected to reflect not only fashion design, merchandising and marketing strategy but also consumer purchase behavior of the future.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.8
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• pp.771-779
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• 2010

This paper presents a method that integrates the geometric path tracking and the obstacle avoidance for nonholonomic mobile robot. The mobile robot follows the path by moving through the turning radius given from the pure pursuit method which is the one of the geometric path tracking methods. And the obstacle generates the obstacle potential, from this potential, the virtual force is obtained. Therefore, the turning radius for avoiding the obstacle is calculated by proportional to the virtual force. By integrating the turning radius for avoiding the obstacle and the turning radius for following the path, the mobile robot follows the path and avoids the obstacle simultaneously. The effectiveness of the proposed method is verified through the real experiments for path tracking only, static obstacle avoidance, dynamic obstacle avoidance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.9
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• pp.960-966
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• 2007

High-efficient machining, which means to machine a part in the least amount of time, is the most effective tool to improve productivity. In this study, a new feed optimization method based on virtual manufacturing was proposed to realize the high-efficient machining in turning process through the cutting power regulation. The cutting area was evaluated by using the Boolean intersection operation between the cutting tool and workpiece. And the cutting force and power were predicted from the cutting parameters such as feed, depth of cut, spindle speed, specific cutting force, and so on. Especially, the reliability of the proposed optimization method was validated by comparing the predicted and measured cutting forces. The simulation results showed that the proposed optimization method could effectively enhance the productivity in turning process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.385-388
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• 1997

As the environmental regulations become stricter, new machining technologies are being developed which takes envi ronmenta 1 aspects into account . Since cut t ing oi I has some impact on environment. many researches are being carried out to minimize the use of cutting oi I. The methods for minimizing cutting oil usage includes the following techniques: I ) Cooling of tools and work piece. 2) Useage of compressed cooling air for the removal of chip. 3) Minimal useage of environment-friendly vegetable cutt:ngoiI for lubrication between chip and tools. Since the turning machine is continuous, tools are under constant thermal load and tool wear increases as the lubricative performance degrades. Also surface roughnesses have a direct influence on turning. In order to examine the characteristics of turningmachining, this work investigates experimentally the degree of tool wear and characteristics of surface roughness in relation to machining conditions, supply methods, and cooling methods.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.3
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• pp.50-55
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• 2008

In this paper, we propose a new shape compensation scheme to make up for the difference in groove radius between the formed tools and the machined bearing raceways, which inherently takes place during machining the ball bearing raceways by the turning process using conventional formed tools. The associated conventional methods of the formed tool design and its modification such as a simple depth compensation method and a graphical compensation method are introduced and the latter, which has been known to be the better of the two, is experimentally investigated in detail to reveal its drawback. The algorithm is given and it is applied to develop a formed tool design program. The program developed by the presented approach is successfully applied to design the formed turning tool for the bearing raceways.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.416-421
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• 2003

To obtain the surface roughness with range from l0nm to In n need a ultra-Precision machine, cutting condition and the study of materials. And n have to also consider the chip and vibration of diamond tool during processing. In this paper, the cutting conditions for getting mirror surface of aluminum alloy have been examined experimentally by using ultra-precision turning and single crystal diamond tool. In generally, the cutting conditions have effect on the surface roughness in ultra-precision turning. The result of surface roughness was measured by the ZYGO New View 200.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.3
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• pp.169-177
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• 2000

In machining screws which are important members in mono pumps or progressive cavity pumps CNC turning center with 3 axes is usually used. This sort of screw machining requires large amount of CL data points and rotational tools are used in machining. When working out the CL data points consideration of possible tool interference is important in order to avoid undercut. This paper describes the checking methods of tool interference in the screw machining on the CNC turning center. First of all a specific shape of a screw cross-section that could commonly be applied to all screws was chosen and then possible tool interference associated with that shape was identified. Checking method was mathematically developed and verified. This checking method will be utilized in the CAM system developed by the authors for screw machining on the 3-axis CNC turning center.