• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.06a
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• pp.1-18
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• 2000

This paper describes firstly a prediction for desirable features of the machine tool in the year 2015 and beyond, and then delineates something definite in relation to some representative machine tools, which could be realised in very near future. The paper depicts furthermore another aspect of future machine tools, I. e., innovative structural designs. In addition, author asserts the importance of grass root-like knowledge, when predicting the desirable feature of machine tools future together with showing some evidences.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.185-191
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• 2006

In this paper, a novel stator hybrid excited doubly salient permanent magnet (SHEDS-PM) brushless machine with a special magnetic bridge is proposed for the first time. The originality of this machine is purposely to add a magnetic bridge in shunt with each PM pole, which not only maintains the stator lamination in its entireness, but also amplifies the effect of DC field flux on PM flux. An equivalent magnetic circuit is presented to clarify the novelty. Based on the 2-D finite element analysis, the static characteristics of the SHEDS-PM machine, namely phase flux linkage, back-EMF, cogging torque, winding inductance and static torque are deduced. The corresponding results on a prototype machine illustrate that the proposed machine is promising for application to electric vehicles.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.3
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• pp.215-223
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• 2005

An electrical machine for a high-speed flywheel for energy storage in large hybrid electric vehicles is described. Design choices for the machine are motivated: it is a radial-flux external-rotor permanent-magnet synchronous machine without slots in the stator iron and with a shielding cylinder. An analytical model of the machine is briefly introduced whereafter optimization of the machine is discussed. Three optimization criteria were chosen: (1) torque; (2) total stator losses and (3) induced eddy current loss on the rotor. The influence of the following optimization variables on these criteria is investigated: (1) permanent-magnet array; (2) winding distribution and (3) machine geometry. The paper shows that an analytical model of the machine is very useful in optimization.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.123-126
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• 2000

In this paper, the portable game machine called W"alking Beat" is designed and implemented not only to propose the new possibilities for the peripheral equipment market of portable acoustic machine but also to overcome the limitation of the acoustic simulation game machine such as the existing Beat Mania. The old game machine can be used only in a particular place, where it is installed. However, in order to get over the constraint on this space problem "Walking Beat Game Machine" is designed to facilitate the portability. In addition, the frequency analysis method using FFT algorithm is employed by regarding the music data for the portable digital acoustic machine as source so that the limitation that the existing game machine depends heavily on the previously registered game contents can be overcome. By making it possible to play games for all the music and putting an emphasis on multimedia trend only to listen to the music, it is speculated that it can contribute to the development of the new culture in the near future.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.213-218
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• 1997

Thermal deformation of machine origin of machine tools due to internal and external heat sources has been the most important problem to fabricate products with higher accuracy and performance. In order to solve this problem, GMDH models were constructed to estimate thermal deformation of machine origin for a vertical machining ceneter through measurement of temperature data of specific points on the machine tool. These models are nonlinear equations with high-order polynomials and implemented in a multilayered perceptron type network structure. Input variables and orders are automatically selected by correlation and optimization procedure. Sensors with small influence are deleted automatically in this algorithm. It was shown that the points of temperature measurement can be reduced without sacrificing the estimation accuracy of $\pm$5${\mu}{\textrm}{m}$. From the experimental result, it was confirmed that GMDH methodology was superior to least square models to estimate the thermal behavior of machine tools.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1011-1017
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• 2011

Servo control loops are a core part in the control architecture of machine tools. Servo control loops manage acceleration, velocity and position of all the axes in a machine tool based on commands. The performance of servo control loops sets the basis for quality of production paris and cycle time reduction. First, this paper presents a general control architecture of machine tools and several control schemes in literature, which can be applicable to machine tools control; including Zero Phase Error Tracking Control (ZPETC) and Cross Coupling Control (CCC). After that, modem control strategies to mitigate the problem of high speed machining are reviewed. In high speed machining, high accelerations excite the machine structure up to high frequencies, thereby exciting the structure's modes of vibration. These structural vibrations need to be damped if accurate positioning or trajectory following is required. Input shaping is an attractive option in dealing with structural vibrations. The advantages and drawbacks of using input shaping technique for machine tools are discussed in detail.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.229-239
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• 2003

The design process of machine tools is regarded as a sequential, discrete, and inefficient works as it requires various kinds of design tools and many working hours. This paper describes an integrated design system embedding a design methodology that can support efficiently and systematically the conceptual structural design of machine tools. The system is a knowledge-based design system and has four machine-tool-specific functional modules including configuration design, configuration analysis, structure design, and structural analysis support module. Through the configuration design and analysis module, a machine configuration appropriate for design requirements is selected, and then the arrangement of ribs fer each structural part is decided in the structure design module. Also, the structural analysis support module is used to evaluate design result by utilizing structural analysis software, ANSYS. The system is applied to design of a tapping machine, and shows that the machine structure can be designed fast and conveniently by processing each design step interactively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1348-1352
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• 2004

An aspherical lens in information technology has been increased in order to enhance the optical performances. There are two kinds of approaches to machine the aspherica surface is generally conducted by the diamond turning machine, precision grinding machine, and polishing machine. This technique, however, has a problem which needs an expensive and high precision machine in order to increase the surface roughness and the machining accuracy. In this paper, a machine, which is able to machine the aspherical surface, was developed to decrease the cost. Also, the machining of the aspherical surface using a cone was carried out experimentally in order to compare the experiment with the simulation. The results showed that the machining experiments of the aspherical surface by using the titled cone were in accordance with the simulation.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.519-521
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• 1994

In this paper, the welding machine with high-frequency inverter is described, which can save energy more than conventional ones with low efficiency. Although for part of welding machine of special type such as MIG, TIG, products were developed by inverter, but it is poor that applied to ordinary ac arc welding machine. Difference between conventional AC arc welding machine and the proposed welding machine is investigated econimically and constructionally. Untill now, kinds of welding machine and its characteristics were also described. The comparison of the proposed welding machine and the conventional is presented in the way of output control.

• IE interfaces
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• v.12 no.4
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• pp.532-539
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• 1999

The first step to design a cellular manufacturing system is to make part-families and machine-cells. This process is called the machine-part grouping. This paper considers a machine-cell size when grouping machine-cells. By considering a machine-cell size, an unrealistically big size of machine-cell which may be caused by the chaining effect can be avoid. A heuristic algorithm which minimizes the number of inter-cell movement of parts considering a machine-cell size is presented. The effectiveness and performance of the proposed heuristic algorithm are compared with those of several heuristic algorithms previously reported. The comparison shows that the proposed heuristic algorithm is efficient and reliable in minimizing the number of inter-cell movement of parts and also prevents the chaining effect.