• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.40-46
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• 2008

Ultraprecision cutting of steels with geometrically defined single crystal diamond tools is handicapped by excessive tool wear. This paper presents a new approach to suppress the wear of single crystal diamond tool in cutting of steels. In general, it is said that the wear of diamond tool is caused by chemically reactive wear under high temperature and high pressure conditions. In order to suppress such chemical reactions, the time of contact between the diamond tool and the steel work in cutting was controlled by employing the intermittent cutting method such as fly-cutting. Series of intermittent cutting experiments have been carried out to control the tool-work contact time by changing one cycle of cutting length and cutting speed. The experimental results were shown that the tool wear was much dependent on the contact time regardless of the cutting speed, and that the wear was much suppressed by reducing the tool-work contact time. It is expected that the steels can be successfully cut with a single crystal diamond tool by controlling the contact time.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1245-1248
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• 2004

This paper presents a new technique to analyze data on the coordinate x, y, z and apply these data to design the motion control to improve the efficiency of the engraving machine so that it can engrave accordingly in 3 dimensions. First, the tool path on the x-y plane is analyzed to be synchronized with the z-axis. The digital data is then sent to the motion control to guide the movement of the engrave point on the x-y plane. Tool path moves along the x-axis with zero degree and different values of the y-axis according to the coordinate of the digital data and the analysis along z-axis to determine the depth for engraving. The depth can be specified from the gray level with the 256 levels of resolution. The data obtained includes the distances on x-axis, y-axis, and z-axis, the acceleration of the engrave point's movement, and the speed of the engrave point's movement. These data is then transfered to the motion control to guide the movement of the engrave point along the z-axis associated with the x-y plane. The results indicate that engraving using this technique is fast and continuous. The specimen obtained looks perfect in 3D view.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.1 s.178
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• pp.113-120
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• 2006

This paper proposed the control algorithm fur aspheric surface grinding and was verified by the experiment. The functions of the algorithm were simultaneous control of the position and interpolation of the aspheric curve. The non-linear formula of the tool position was derived from the aspheric equations and the shape of the tool. The function was partitioned by an certain interval and the control parameters were calculated at each control section. The movement in a session was interpolated with acceleration and velocity. The position error was feed-backed by rotary encorder. The concept of feedback algorithm was correcting position error by increasing or decreasing the speed. In the experiment, two-axis machine was controlled to track the aspheric surface by the proposed algorithm. The effect of the control and process parameters was monitored. The result showed that the maximum tracking error was under sub-micro level for the concave and convex surfaces.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.596-602
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• 2010

In this study, a fmite element model was developed for analysis of feeding a structure in open loop control The finite element analysis (FEA) can simulate dynamic behavior of the structure of a machine tool rapidly traveling with a screw feeding driving system. The feeding mechanism was implemented with screw element of the FEA tool used in this study. The procedure was developed for the dynamic transient FEA. First, motion parameters such as jerk and velocity were introduced for the structure to be fed in open loop control When its traveling distance was determined, set-points for the distance were generated based on the motion parameters. The set-points were applied to the FE model constructed for the traveling structure. The FEA was executed and evaluated. In this study, the FEA procedure was applied to the column of a machine tool and the dynamic behavior of the column was evaluated. The FEA helps in evaluation of the motion characteristics of a structure. The convergence time of the structure vibration posterior to feeding termination can be estimated and the stiffness of the flexible structure is also evaluated against jerk, and acceleration. It provides the feeding force which is helpful in selection of the feeding motor.

• International Journal of Highway Engineering
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• v.16 no.5
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• pp.109-119
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• 2014

PURPOSES : The control delay in seconds per vehicle is the most important traffic operational index to evaluate the level of service of signalized intersections. Thus, it is very critical to calculate accurate control delay because it is used as a basic quantitative evidence for decision makings regarding to investments on traffic facilities. The control delay consists of time-in-queue delay, acceleration delay, and deceleration delay so that it is technically difficult to directly measure it from fields. Thus, diverse analysis tools, including CORSIM, SYNCHRO, T7F, VISTRO, etc. have been utilized so far. However, each analysis tool may use a unique methodology in calculating control delays. Therefore, the estimated values of control delays may be different by the selection of an analysis tool, which has provided difficulties to traffic engineers in making solid judgments. METHODS : This study was initiated to verify the feasibility of diverse analysis tools, including HCM methodology, CORSIM, SYNCHRO, T7F, VISTRO, in calculating control delays by comparing estimated control delays with that measured from a field. RESULTS : As a result, the selected tools produced quite different values of control delay. In addition, the control delay value estimated using a calibrated CORSIM model was closest to that measured from the field. CONCLUSIONS : First, through the in-depth experiment, it was explicitly verified that the estimated values of control delay may depend on the selection of an analysis tool. Second, among the diverse tools, the value of control delay estimated using the calibrated microscopic traffic simulation model was most close to that measured from the field. Conclusively, analysts should take into account the variability of control delay values according to the selection of a tool in the case of signalized intersection analysis.

• Journal of Astronomy and Space Sciences
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• v.37 no.3
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• pp.187-197
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• 2020

In order to avoid the high cost and high risk of demonstration mission of rendezvous-docking technology, missions using nanosatellites have recently been increasing. However, there are few successful mission cases due to many limitations of nanosatellites like small size, power limitation, and limited performances of sensor, thruster, and controller. To improve the probability of rendezvous-docking mission success using nanosatellite, a rendezvous-docking phase analysis tool for nanosatellites is developed. The tool serves to analyze the relative position and attitude control of the chaser satellite at the docking phase. In this tool, the Model Predictive Controller (MPC) is implemented as a controller, and Extended Kalman Filter (EKF) is adopted as a filter for noise filtering. To verify the performance and effectiveness of the developed tool for nanosatellites, simulation study was conducted. Consequently, we confirmed that this tool can be used for the analysis of relative position and attitude control for nanosatellites in the rendezvous-docking phase.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.60-63
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• 1997

Recently, factory automation and shop floor control system need a web based remote monitoring technology to control effectively machine tool. This paper describes a web based remote monitoring system which is concerned with open architecture controller for machine tool. The environment of this system consists of a lot of elements such as web server, database, machine tool, pc based controller, client computers and script programs, also which is interconnected by network including intranet or internet. Designed script programs, also which is interconnected by network including intranet or internet. Designed script program service current status and faults information of machine to remote users who want to monitor machine tool. Additionally those have various functions to service we board for q&a, downloading data and information of after-service managers.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.1
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• pp.9-16
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• 2015

The machining-chatter stands for a sudden relative vibration appeared between a material and a tool while processing with a machine. This chatter is key factor that seriously affects the quality of processed materials as well as being a factor which causes serious damages to the tool and the machine. This study is related to the monitoring and smart control of chatter problem that can compensate machining-chatter faster and produce processed goods with more precision by autonomous compensation. The above-mentioned machining-chatter compensator includes the chatter vibration sensor and the chatter compensator that estimates the compensation value according to the sensor detecting the chatter vibration of machine-tool and the chatter vibration detected from the sensor while having a feature of being organized by interlocking with the machine-tool controller.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.12
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• pp.1088-1095
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• 2008

5-axis NC machining has a good advantage of the accessibility of tool motion by adding two rotary axes. It offers numerous advantages such as expanding machining fields in parts of turbo machineries like impeller, propeller, turbine blade and rotor, reasonable tool employment and great reduction of the set-up process. However, as adding two rotary axes, it is difficult to choose suitable machining conditions in terms of tool path, tool posture, feedrate control at a tool tip and post-processing. Therefore in this paper, it is proposed to decide suitable machining condition through an experimental method such as adopting various tool paths, tool postures, and feedrate types. Machining experiment on AL7075 for impeller is performed to define suitable machining condition, and measurement of surface roughness on machined surfaces depended on each machining condition is performed. By defining suitable machining condition, we should have conclusion as improving the surface quality in the aspect of surface roughness and machined shape of surface.

• Journal of Practical Engineering Education
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• v.10 no.2
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• pp.89-94
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• 2018

In injection molding, the tool temperature has a great influence on the quality of the molded article. The appropriate temperature is determined by the molding material and the quality required for the molded part, and the important point is that the temperature should be stable. First, the tool temperature should be set in accordance with the quality required by the molded article within the range of the tool temperature conditions suitable for the material. That is, the tool temperature changes depending on the importance of the surface gloss of the molded article, shortening of the molding cycle, prevention of deformation, degree of shrinkage, ease of resin flow and the like. In order to improve practical tool technology, we propose a training model of the difficult process of tool temperature control which can be utilized in industry that design and manufacture injection mold.