• 한국정밀공학회지
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• 제22권1호
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• pp.39-46
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• 2005

In this study, unsintered, presintered and full-sintered low purity alumina ceramics were machined with various tools to clarify the machinability and the optimum cutting conditions. The main conclusions obtained were as follows. (1) Machined with alloy steel tool, the machinability of the presintered ceramics becomes better with the decrease of presintering temperature, but that of unsintered ceramics(white body) was extremely poor. (2) In the case of carbide, K01, the tool life in machining the white body was the longest, and the machinability of presintered ceramics becomes poorer with the increase of the presintering temperature. (3) The K01 tools exhibit longer life than the P10 tools in machining both the white body and the ceramics presintered at $1450^\circC$ or higher temperatures, but the P10 tools shows longer tool life than the K10 tools in machining of the ceramics presintered at temperatures below $1450^\circC$.

• 한국정밀공학회지
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• 제10권1호
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• pp.142-146
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• 1993

The vibrations of the main spindle of the M/C tools are most important in the consideration of the dymamic performance of the M/C tools. In order to resolve and predict the dynamic behaviour of the main syindle it is necessary to have the mathematical model of the system. The system identification is the procedure to provide us with the mathematical model of the procedure of the system identification of the main spindle of the M/C tools to predict the dynamic behaviour of the machine and further to have the basis for the design of M/C tools.

• 대한산업공학회지
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• 제32권2호
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• pp.82-90
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• 2006

Reconfigurability of machine tools is one of the critical factors to realize the responsive manufacturing systems to satisfy the mass customization production. This paper presents the methods to model the reconfigurable machine tools (RMTs) on Internet in response to change in the machining requirements. Specifically, the structure and motion model of machine tools using module combination rules and connectivity graph are developed. And we developed Internet-based simulator for designing of RMTs (ISD-RMT). In response to the user requirements, various structures of RMTs can be derived using the module combination rules and connectivity graph relationships. In addition, the user can verify generating structures through the control and simulation procedures.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.778-783
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• 1994

In operating automated manufacturing system, the long term stability and reliability of NC machine tools become most critical issues. Especially the machining accuracy is dominated by the thermal deformation of machine tools which remains still unsolved and causes troubles in manufacturing operations. Although researches have been carried out on the thermal behavior of a machine tools to minimize or control the thermal deformation of machine tools, the computer models for an analysis of the thermal behacior in machine tools has yet to appear in the open literature. The object of the paper is to present a method of modeling the thermal behavior of a machine tool. The method will make use of finite elements ad be capable of modeling whole machine structures as well as of heat generation processes in the kinematic system components. And temperature distributions and thermal deformations of a CNC lathe are analyzed using the finite element method and are compared with those measured in practice.

• 한국정밀공학회지
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• 제25권5호
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• pp.52-59
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• 2008

The accuracy of the machine tools is degraded because of thermal error of structure due to thermal variation. To improve the accuracy of a machine tools, measurement and prediction of thermal error is very important. The main part of thermal source is spindle due to high speed with friction. The thermal error of spindle is very important because it is over 10% in total thermals errors. In this paper, the suitable thermal error prediction technology for machine tools with open architecture controller is developed and implemented to machine tools. Two thermal error prediction technologies, neural network and multi-linear regression, are investigated in several methods. The multi-linear regression method is more effective for implementation to CNC. The developed thermal error prediction technology is implemented on the internal function of CNC.

• 한국정밀공학회지
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• 제14권7호
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• pp.15-21
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• 1997

This paper presented a linear motion accuracy by using two-dimensional probe with the master block and the square for NC machine tools. This measuring system could be measured motion error due to numerical control system. The results of measurement and simulation for motion error were similar, and so, this system had enough accuracy to measure a linear motion accuracy for NC machine tools. The experimental results are as follows. 1. This measuring system could be measured motion error due to mumerical control system. 2. The results of measurement and simulation for motion error were similar. 3. This measuring system had enough accuracy to measure a linear motion accuracy for NC machine tools.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2009년도 춘계 학술논문 발표대회 학계
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• pp.143-147
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• 2009

Graduates from engineering colleges are demanded to have been acquired some abilities and qualities during their undergraduate years through the standard of the so-called "programmed learning results and evaluation" This paper aims at analyzing the learning results evaluation tool for graduates from the architectural engineering department through the examples of the colleges with engineering accreditation in Korea, and suggesting a more appropriate programmed learning result evaluation tool. The basic theories on programmed learning results were studied, and then the previous study examples were researched. The study objects were limited to the fourteen colleges which offered the examples of the learning results evaluation tools of the colleges with engineering accreditation in Korea. Types and the present situation of those evaluation tools were analyzed. In addition, the proposals for the evaluation tool of programmed learning results and the performance standard were suggested for those with an engineering accreditation, based on the case study of the performance standards of each college with an engineering accreditation. The study results showed that much more national research needs to be conducted to clarify the standards of selecting an evaluation tool and a performance standard appropriate for the level of each college so that it can make a proper proposal.

• 시스템엔지니어링학술지
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• 제5권2호
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• pp.63-69
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• 2009

For the effective and efficient system development, it is provided of complex and diverse disciplines, analysis and design, points of views for decisions making, technical information management, assurance of products, and so on to be integrated and ensured. Systems engineering is conducted through a process and is implemented by tools based on relevant methodologies. Systems engineering environment should be provided to support the systems engineering process, method, and tools used on the project. In this paper, the essential environment in performing works in a organization applying systems engineering on the basis of system life cycle was reviewed. The present states on establishment of the systems engineering in Korea Railroad Research Institute were also examined with some reviews of other cases.

• 한국정밀공학회지
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• 제9권2호
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• pp.61-68
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• 1992

To meet the requirements for accuracy, productivity and reliability of machine tools, it is necessary to evaluate the chatter-free machining performance and to improve the dynamic performance of machine tools. In order to perform dynamic design of machine tools reasonably and effectively, the joint parts must be modelled accurately because their characteristics affect significantly on the total characteristics of machine tool. In this paper, an approach which identifies the effect of joint parts on the performance of total machine tool structure was proposed. That uses the experimental modal analysis, the finite element method and the sensitivity analysis method. The effectiveness of this approach was confirmed by applying it to structures with bearing joints. And as a result of the application, the change of dynamic characteristics of bearing joints was indentified.

• 전기학회논문지
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• 제64권6호
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• pp.935-939
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• 2015

In this paper, we analyze indoor visible light communication environment based on LightTools. If the environments for VLC are too various, it is not easy to analyze the VLC environment using mathematical techniques. To overcome this problem, we use LightTools program for the analysis of various VLC environment.