• International Journal of Precision Engineering and Manufacturing
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• 제7권4호
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• pp.34-39
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• 2006

High-precision centerless grinding machines are emerging as a means of finishing the outer diameter grinding process required for ferrules, which are widely used as fiber optic connectors. In this study, a structural characteristic analysis and evaluation were carried out using a virtual prototype of a centerless grinding machine to realize systematic design technology and performance improvements required to manufacture ferrules. The prototype consisted of a concrete-filled bed, hydrostatic grinding wheel (GW) and regulating wheel (RW) spindle systems, a hydrostatic RW feed mechanism, a RW swivel mechanism, and on-machine GW and RW dressers. The loop stiffness values of the centerless grinding machine were estimated based on the relative displacements between the GW and RW caused by grinding forces. The simulated results illustrated that a concrete-filled bed considerably improved the structural stiffness and accuracy of a high-precision centerless grinding machine.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.32-36
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• 2002

This paper presents the structural characteristic analysis of a centerless grinding machine with concrete bed. The centerless grinding machine is composed of grinding wheel head, regulating wheel head, concrete bed, wheel dresser and so on. Especially, the concrete bed is introduced to improve the static, dynamic and thermal characteristics of the centerless grinding machine. The structural analysis model of centerless grinding machine is constructed by the finite element method, and the structural characteristics in the design stage are estimated based on the structural deformation and harmonic response under the various testing conditions related to gravity force and directional farces

• 한국정밀공학회지
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• 제22권2호
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• pp.172-179
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• 2005

A high-precision centerless grinding machine has been recognized as a core equipment performing the finish outer-diameter grinding process of ferrules which are widely used as fiber optic connectors. In this study, in order to realize the high-precision centerless grinding machine, the structural characteristic analysis and evaluation are carried out on the virtual prototype consisted of the steel bed, hydrostatic GW and RW spindle systems, hydrostatic RW feed mechanism, RW swivel mechanism, and on-machine GW and RW dressers. The loop stiffnesses of centerless grinding machine are estimated based on the relative deformations between GW and RW caused by the grinding forces. And the simulated results illustrate that the concrete-filled bed has the considerable effect on the improvement of the structural stiffness of centerless grinding machine.

• International Journal of Concrete Structures and Materials
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• 제4권1호
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• pp.51-54
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• 2010

Fly ash is used in concrete to improve the fresh and hardened properties of concrete, including workability, initial hydration temperature, ultimate strength and durability. A primary limitation on the use of large quantities of fly ash in blended cement concrete is its slow rate of strength gain. Prior studies investigated the effects of grinding fly ash and fly ash fineness on the performance of concrete containing fly ash. This study aims to discover the sources of those effects, to verify the compressive strength behavior of concrete made with raw and processed Class C fly ash, and to investigate the properties of fly ash particles at the microscopic level. Concrete cylinder test results indicate that grinding fly ash can significantly benefit the early age strength as well as the ultimate strength of concrete with ground fly ash. Therefore, it is demonstrated that grinding fly ash increases its reactivity. Scanning Electron Microscopy was then used to investigate the physical effects of the grinding process on the fly ash particles in order to identify the mechanism by which grinding leads to improved concrete properties.

• 대한토목학회논문집
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• 제33권4호
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• pp.1683-1691
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• 2013

콘크리트 표면절삭 작업은 포장면의 노화 또는 파손으로 인한 보수작업과 그루빙(Grooving) 시공을 통한 포장면의 배수능력을 강화하거나 평탄성을 확보를 위하여 자주 적용되는 공법이다. 그러나 그 작업특성이 노동집약적이고 분진, 슬러지, 소음 등으로 인한 유해한 작업환경을 보유하고 있으며 장비를 다루는 기능공의 숙련도에 따라 생산성 및 절삭품질의 편차가 큰 경향이 있다. 따라서 장비 조종자가 각종 위험에 노출되지 않도록 하기 위한 원격조종 콘크리트 표면절삭 장비 개발이 필요하다. 원격 조종 환경에서는 조종자가 객관적인 절삭 품질을 확인함과 동시에 장비가 계획 경로에 따라 작업이 올바르게 수행되고 있는지를 확인할 수 있도록 하는 지원시스템이 필요케되는 바, 본 연구에서는 머신비전 시스템(Machine Vision System)과 GPS를 적용하여 네트워크 카메라로 촬영한 절삭면의 이미지를 디지털 영상처리(Image Processing)과정을 거쳐 객관적이며 품질관리 프로세스가 자동화된 시스템을 구축하였다. 또한 장비의 현재 위치와 방향, 속도, 계획된 경로와의 오차정보 그리고 작업의 진척도 등을 종합적으로 산출하여 워크 스테이션에 표시함과 동시에 머신 비전 시스템에 의한 작업 품질 정보와의 통합을 위한 프로그램을 개발하였으며, 현장 적용 테스트를 통해 본 기술을 검증하였다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.983-986
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• 2007

콘크리트 표면절삭 작업은 콘크리트 표면의 평탄성 및 부착성을 필요로 하는 공사에서 빈번히 사용되고 있으나 작업형태가 노동집약적이며, 유해한 작업환경을 보유하고 있다. 또한 장비를 다루는 기능공의 숙련도에 따라 생산성 및 절삭품질의 편차가 큰 경향이 있다. 그러므로 주변 환경오염 방지와 장비 조종자가 위험에 노출되지 않도록 하기 위한 원격조종 콘크리트 표면절삭 장비 개발이 요구된다. 그러나 원격 조종 시스템에서 조종자가 절삭면의 품질을 측정하기 난해하고 품질에 대한 객관적인 판단을 내리기가 어려우므로, 본 연구에서는 머신비젼시스템(Machine Vision System)을 적용하여 네트워크 카메라로 촬영한 절삭면의 이미지를 디지털 영상처리(Image Processing)과정을 거쳐 그 결과를 그래픽 MMI(Man-Machine Interface) 프로그램에 표현함으로써 품질관리 시스템을 구축하였다. 머신비전 알고리즘은 콘크리트 절삭면의 디지털 영상처리 알고리즘을 의미하며 본 논문에서 제안된 알고리즘을 적용하여 콘크리트 절삭면의 객관적인 품질관리 기준을 제시하고자 한다.

• 한국정밀공학회지
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• 제23권1호
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• pp.193-200
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• 2006

To perform the finish grinding process of ferrules which are widely used as fiber optic connectors, a high-precision centerless grinding machine is necessary. The high-precision centerless grinding machine is consisted of the hydrostatic GW and RW spindle systems, hydrostatic RW feeding mechanism, RW swivel mechanism, on-machine GW and RW dressers, and concrete-filled steel bed. In this study, the thermal characteristics of the high-precision centerless grinding machine such as the temperature distribution, temperature rise and thermal deformation, are estimated based on the virtual prototype of the grinding machine and the heat generation rates of heat sources related to the machine operation conditions. The reliability of the predicted results is demonstrated by the temperature characteristics measured from the physical prototype. Especially, the predicted and measured results show the fact that the high-precision centerless grinding machine has very stable thermal characteristics.

• International Journal of Concrete Structures and Materials
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• 제5권2호
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• pp.113-117
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• 2011

The purpose of this work is the comparative study for grinding of two cement clinkers. X-ray fluorescence, physical and granulometric tests and optical microscopy were used to characterize the clinkers. Also grinding tests were carried out for ten samples to determine the parameters influencing grindability of its clinkers. The results of calculation of the energies of grinding according to the law developed by Von Rittinger and the study of the microstructure of the two clinkers shows good agreements. Indeed, frequent clusters of belite which indicate a lack of uniformity and fineness have an effect on lowering the grindability. The obtained analyses and the results enabled us to interpret the granulometry and the microstructure of clinker to control quality and resistance.

• Journal of Multimedia Information System
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• 제9권2호
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• pp.127-136
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• 2022

In MMORPGs, there are many problems with the Grinding player experience. This research divides the Grinding player experience into four dimensions: Grinding in-Autonomy, Competence, Relatedness and Positive affect through theoretical investigation of game experience. Through the study of Litman (2008), Curiosity is divided into two dimensions, I-Type Curiosity and D-Type Curiosity, and the relationship between Curiosity and Grinding player experience is studied. By distributing questionnaires, collecting data, and using SPSS software to conduct reliability analysis, validity analysis, correlation analysis and multiple regression analysis on the data, it is verified that in MMORPG, I-Type Curiosity can positively affect Grinding in-Autonomy, Competence, Relatedness and Positive affect. D-Type Curiosity can positively affect Grinding in-Autonomy, Competence and Positive affect, but D-Type Curiosity has no statistical relationship with Grinding in-Relatedness. And through the standardized coefficient (Beta) value, between the Curiosity factors, I-Type Curiosity has a greater impact on Grinding in-Autonomy and Positive affect, and D-Type Curiosity has a greater impact on Grinding in-Competence. Finally, from the perspective of I-Type Curiosity and D-Type Curiosity, combined with the drawbacks of the MMORPG Gringding mechanism, some concrete and feasible suggestions and optimization schemes are put forward to improve the Grinding player experience. This research result can provide some feasible suggestions for MMORPG developers and designers, optimize the MMORPG Grinding mechanism from the perspective of I-Type Curiosity and D-Type Curiosity, and improve the Grinding player experience. It can provide appropriate assistance for the improved development of MMORPG games.

• International Journal of Precision Engineering and Manufacturing
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• 제8권1호
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• pp.32-37
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• 2007

The outer diameter finishing grinding process required for ferrules, which are widely used as fiber optic connectors, is carried out by high-precision centerless grinding machines. In this study, the thermal characteristics of such a machine, for example, the temperature distribution, temperature rise, and thermal deformation, were estimated based on a virtual prototype and the heat generation rates of heat sources related to normal operating conditions. The prototype consisted of a concrete-filled bed. hydrostatic grinding wheel (GW) and regulating wheel (RW) spindle systems, a hydrostatic RW feed mechanism, a RW swivel mechanism, and on-machine GW and RW dressers. The reliability of the predicted results was demonstrated using temperature characteristics measured from a physical prototype. The predicted and measured results indicated that this particular high-precision centerless grinding machine had very stable thermal characteristics.