• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2001년도 학술대회 논문집
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• pp.25-28
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• 2001

Bi-2212 HTS tube was fabricated by centrifugal forming process(CFP). As a variation of melt casting process(MCP) or centrifugal casting technique, the centrifugal forming process is a flexible method for manufacturing Bi-2212 bulk tubes and has been optimized to achieve smooth surface and uniform thickness. At this process, the slurry was prepared in the mixing ratio of 10:1 between Bi-2212 powder and binder and initially charged into the rotating mold under the speed of 300~450 rpm Heat-treatment was performed at the temperature ranges of 860 ~ $890^{\circ}C$ in air for partial melting. The HTS tube fabricated by centrifugal forming process at $890^{\circ}C$ under the rotating speed of 450 rpm was highly densified and the plate-like grains with more than 20$\mu$m were well oriented along the rotating axis. The measured Tc and Jc at 10K were around 85K and 3,000A/cm2 respectively.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.83-88
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• 2001

In order to suggest the proper optimal conditions of the CNC milling machining for the Thin-wall surface, some experiments were carried out. The process was applied in the aerospace industry for the machining of light alloys, notably aluminium. In recent year, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. And the end mill is an important tool in the milling process. A typical example for the end mill is the milling of pocket and slot in which a lot of material is removed from the workpiece. Therefore the proper selection of cutting parameter for end milling is one of the important factors affecting the cutting cost. In this paper, we choose the optimal parameters(cutting forces) to cut thin-walled Al part by experiment.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.100-105
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• 2003

With the recent development of machining technology, high speed machining process is widely used for-the mold and difficult-to -cut-materials machining since it allows achieving high productivity and surface quality. However, during the high speed machining process, high cutting speed and feed rate can cause abrupt tool life decrease due to rapid rising of the cutting tool temperature. Such situation may cause increase of machining cost. Thus, in this study, developed optimization algorithm is applied to determine optimal machining variables for multiple high speed machining. The R-T characteristic curve for machining economics problems with a linear-lorarithmic tool life model is determined by applying sensitivity analysis. finally, a series of high speed machining experiments are performed to determine the desired optimal machining variables, and the results are analyzed.

• 한국공작기계학회논문집
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• 제11권5호
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• pp.1-6
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• 2002

This study is to investigate the characteristics of the surface around a hole on inlet and outlet of product which are manufactured by face mill or end mill cutting with a hole or a pocket in its surface. Furthermore, experiments for optimization of process conditions to minimize the change of characteristics of milling cut surface after a hole cutting operation are implemented. This result is apply to manufacture of mold products and metal products by diecasting.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.420-425
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• 2003

Generally, reverse engineering means getting CAD data from unidentified shape using vision or 3D laser scanner system. In this paper, we studied unidentified model by machine vision based reverse engineering system to get information about in-processing model. Recently, vision technology is widely used in current factories, because it could inspect the in-process object easily, quickly, accurately. The following tasks were mainly investigated and implemented. We obtained more precise data by corning camera's distortion, compensating slit-beam error and revising acquired image. Much more, we made similar curves or surface with B-spline approximation for precision. Until now, there have been many case study of shape recognition. But it was uncompatible to apply to the field, because it had taken too many processing time and has frequent recognition failure. This paper propose recognition algorithm that prevent such errors and give applications to the field.

• 한국공작기계학회논문집
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• 제12권4호
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• pp.23-28
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• 2003

This paper describes the machining characteristics of a developed micro grooving machine. Experiments have been conducted on the various grooving condition such as spindle revolution speed, feed rate and depth of groove. V and U-shaped blade tool and STD11 workpiece was used in this study. To evaluate the developed micro grooving machine, AE signal obtained from each experimental condition was analyzed, and cutting stability was compared with the surface state. As a result this study presented the process to optimize grooving condition and possibility of application of AE technique in groove machining.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.445-449
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• 2001

The tool wear that is developed by long-term machining in mold manufacturing with machining center makes a severe influence to the accuracy and the surface roughness. In this reason, tool-wear supervising system which has guaranteed high accuracy and high speed is needed to improve the measurement quality. Touching probe and touch sensor are widely used to measure the tool profile at on-machine measurement. In this paper, using the newly developed electric touch point measuring system, the Automatic Tool Compensation System is developed to correct the error of tool diameter resulted from the wear, and the operating method of this system is also provided.

• International Journal of Precision Engineering and Manufacturing
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• 제7권3호
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• pp.8-13
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• 2006

Plunge milling process is used for machining hole and is widely used in aerospace, automobile, and die/mold industries. The cutter is fed in the direction of spindle axis which has the highest structural rigidity. The kinematics of plunge milling differs from the traditional turning and milling in aspect of tool engagement and chip generation. This paper proposes the mechanistic cutting force model for plunge milling. Uncut chip thickness is calculated using the present cutter edge position and the previous cutter edge position. Instantaneous cutting force coefficients, which depend only on instantaneous uncut chip thickness, are derived based on the mechanistic approach. The developed cutting force model is verified through comparison of the predicted and the measured cutting forces.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.429-433
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• 1997

High-speed and high-precision are trendy at present in the development of machine tools which are required for various fields of industry such as semiconductor, automobde, mold fabricat~on and so on. High damping capacity of the structure is an iniportant factor to ohtain precise products without vibration during manufacturing caused by rapid trarisportatm and rotation of spindle unit Resin concrete have high potential for machine tool bed due to its good damping characteristics. In this study, the statlc and dynamic characteristics of the machine tool bed were analysed. Also, the hybrid machine tool bed, made of steel base and polyester resin concrete material, was manufactured and its good dynamic characteristics were proved experimentally.

• 한국공작기계학회논문집
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• 제10권2호
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• pp.64-72
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• 2001

Weld line is one of serious troubles which are observed in a plastic part manufactured by a injection molding process. This is caused by many process factors, which are molding pressure, temperature, velocity, location of a injection gate, mold geometry and material properties. investigation on the effects of these process factors to the appearance of a weld line was carried out using a finite element method. Filling and packing analyses were carried out by modifying both the configuration of the injection gates and cavity thickness. Proper locations of the injection gates could be determined by considering molding pressure, temperature, velocity and frozen layer, and whereby the weld line was controled. In order to make a weak appearance of the weld line, flow velocity and flow front in a cavity were also investigated by modifying a cavity thickness. As a result, flow front was extended around the corner in the cavity by changing the flow velocity and hence the appearance of the weld line was much weakened.