• 한국정밀공학회지
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• 제19권9호
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• pp.66-73
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• 2002

Since cross-feed directional cutting force which is normal to machined surface directly influences the machined surface of the workpiece and total force loaded in cutter, it is necessary to estimate this force to control the roughness of the machined surface and total force in cutter. However, there have been difficulties in using the current existing in a stationary motor for cutting state prediction because of some unpredictable behavior of the current. Empirical approach was conducted to resolve the problem. As a result, we showed that the current and its unpredictable behavior are related to the infinitesimal rotation of the motor. Subsequently, the relationship between the current and the cutting force was identified with the error less than 50%. And, the estimation results of the two machine tools with different characteristics were compared to each other to confirm the validity of the presented estimation method and the characteristics of current of the stationary feed motor.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.475-478
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• 2004

In this paper, a magnet-type automatic pipe cutting machine that binds itself to the surface of the pipe using magnetic force and executes unmanned cutting process is proposed. During pipe cutting process when the machine moves around the pipe laid vertical to the gravitational field, the gravity acting on the pipe cutting machine widely varies as the position of the machine varies. That is, with same driving force from the driving motor the cutting machine moves faster when it climbs down the surface of the pipe and moves slower when it climbs up to the top of the pipe. To maintain a constant velocity of the pipe cutting machine and improve the cutting quality, the authors adopted a conventional PID controller with a feedforward effort designed based on the encoder measurement of the driving motor. It is, however, impossible for the encoder at the motor to measure the absolute position and consequently the absolute velocity of the cutting machine in the case where the slip between the surface of the pipe and wheel of the cutting machine is not negligible. As an attempt to obtain a better estimation of the absolution angular position/velocity of the machine the authors proposes the use of the MEMS-type accelerometer which can measure static acceleration as well as dynamic acceleration. The estimated angular velocity of the cutting machine using the MEMS-type accelerometer measurement is experimentally obtained and it indicates the significant slipping of the machine during the cutting process.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.123-127
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• 1999

This paper suggests the establishment of high-accuracy and high-efficiency machining method of scroll shape workpiece by using the feed control method. The cutting paths for machining the inside and outside surfaces of the scroll-shape workpiece are calculated, and the calculation method of the cutting chip areas based on the coordinate of the base circle is shown. A feed control method is proposed for a constant cutting area and cutting force. By machining test of scroll shape workpiece, The machined accuracy of wrap, tool wear, and surface roughness are evaluated. By this method, Reduction of the machining time and large increase of the efficiency can be expected.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.158-162
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• 2006

A lot of pieces of iron plate are used to build a ship. The states of cutting surface of iron are however bended or ununiformly cuttled by cutting machine. These may cause bad Quality of painting, and shorter lifetime of iron by rust. In this paper, a new approach of grinding force control method which teaching of robot is not required is proposed to avoid long preparation time of robot and to improve the productivity. The way used in this paper is just like a blind man works through the road with stick only.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.1019-1022
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• 2002

Pipe-cutting machines have been used in many fields. Recently, an automatic pipe-cutting machine that uses magnet has born developed. In this paper, a magnetic-type automatic pipe-cutting machine that attaches itself and performs unmanned cutting process is proposed. It is designed that there is a room at the bottom of its body to contain a magnet. And it uses magnetic force between the magnet and the pipe surface to prevent slip and to attach the machine to the pipe against gravity. Also the magnetic force is adjustable by changing the gap between the magnet and the pipe. This machine is, however, necessary to control cutting velocity for the elevation of work efficiency and the adjustable faculties. During pipe cutting process, the gravity acting on the pipe-cutting machine widely varies. That is, the cutting machine gets fast when moving from the top to the bottom of the pipe and slow when moving from the bottom to the top. Actually the system is kind of a non-linear system where the gravity is function of climbing angle of the cutting machine along the pipe. Especially jerking motion is critical. Therefore, authors design the non-linear controller that estimates the current position of the machine along the pipe and compensates the effect of gravity in this paper. It receives the feed back signal from the encoder.

• 한국식품조리과학회지
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• 제17권4호
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• pp.329-337
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• 2001

This study was carried out to observe the changes of Oiji quality during fermentation by preparing the samples with various functional ingredients (Chinese pepper(Sancho), onion, pine leaves) exerting antimicrobial effect. The pH values of all experiment groups decreased significantly in proportion to the ripening period(P＜0.05). Control and Chinese pepper-added groups showed a rapid decrease in pH after 5 days of ripening, and Onion- and Pine leaves-added groups after 3 days of ripening. All experimental groups showed the lowest pH value at the 20th day of ripening. Rapid permeation of salt solution occured in all groups at the 3rd day of ripening. But the increase rate of salt permeation decreased gradually after 3 days of ripening. Lightness and redness in color decreased gradually in all groups, but the redness of Pine leaves-added group increased at the 30th day of ripening. Yellowness of control group was higher than that of others after 10 days of ripening(P＜0.05), and the yellowness of pine leaves-added Oiji was the lowest among all after 5 days of ripening(P<0.05). The maximum cutting force of raw cucumber was observed at stem end followed by blossom end and middle part, and the Oiji samples also showed the same order at the early stage of ripening. In general, maximum cutting force of minor ingredient-added Oiji was higher than that of control and maximum cutting force was decreased at the 30th day of ripening. Onion-added group showed the highest value among all at the 40th day of ripening. Chinese pepper-added group was ranked low, but onion- and pine leaves-added groups were ranked high in sensory evaluation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1352-1355
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• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surface. However, as the accuracy requirement gets tighter and desired surface contours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated depth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in addition to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamometer. Based on the parameter estimation of cutting dynamics and the admittance model-based nanodynamic control scheme, simulation results are shown.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.8-13
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• 2000

In this paper, a new adaptive cross-coupling control (CCC) method with an improved contour error model is proposed to maintain contouring precision in high-speed nonlinear contour machining. The proposed method utilizes variable controller gains based on the instantaneous curvature of a contour and the feedrate command. In addition, a real-time federate adaptation scheme is included in the proposed CCC to regulate cutting force. The proposed method is evaluated and compared with the conventional CCC for nonlinear contouring motion through computer simulations. The simulation results show that the proposed CCC improves the contouring accuracy and regulates cutting force more effectively than the existing method.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.116-121
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• 1999

At the exit stage of drilling, the burr generates and deburring process is required to remove it. Since the additional process reduces productivity, a burr minimization technique is necessary in the servo system of drilling machines. In this research, cutting force is modelled with tool geometry and the optimal velocity profile with which the desired cutting force maintains is generated to minimize burr. Experiments show that the proposed velocity profile tracking effectively minimizes burr compared to the constant velocity feed.

• International Journal of Precision Engineering and Manufacturing
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• 제4권3호
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• pp.42-47
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• 2003

In Part 2 of this paper, the dynamic cutting force model, thermal behavior model, and feed drive model used in the development of a virtual machine tool (VMT) are briefly described. Some results are presented to verify the proposed models. Experimental data agreed well with the predicted results fer each model. A comprehensive software environment to integrate the models into a VMT is also proposed.