• 한국정밀공학회지
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• 제19권2호
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• pp.58-64
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• 2002

In these days, according to increasing the technical development, the dimension of a product goes up for ultra-precision. For the net shape manufacturing, grinding is a important process that influences directly the accuracy and the integrity of produced products. In this study, an experimental evaluation was carried out. Workpiece materials were used STD11, SUS304, and STB2 in accordance with varing condition of feedrate and depth of cut. From measuring the grinding force and the surface roughness, material characteristics of grinding by using CBN wheel were examined.

• 한국기계가공학회지
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• 제6권4호
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• pp.71-75
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• 2007

Geometrical error of ultra-precision machining due to spherical tool alignment error is analyzed. Deviation of spherical edge, ranged several ten micrometers, generates vertical and horizontal error of tool path and affects profile accuracy of machined surface. Simulation of machined error shows effect of tool alignment error and enables to estimate alignment error. This work provides technical insights into the minimizing of geometrical error of ultra-precision machining.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.86-93
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• 2005

In this paper, we discuss the merits of mechanical machining to generate micro features on large surfaces. An overseas technology trend related to the micro machining and dedicated machinery is also presented. We provide an overview of what characteristics the machinery is required to have to generate micro features on large surfaces and what kind of technical barriers need to be overcome to put the technology to practical use.

• 한국정밀공학회지
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• 제30권11호
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• pp.1129-1137
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• 2013

We report a centerless grinding machine which can perform multi-function with 600 mm wide grinding wheels. By increasing manufacturing area, long workpiece such as camshaft and steering shaft, is allowed to grind more quickly, compared with cylindrical grinding system. In this paper, the design of centerless grinding machine puts emphasis on symmetry to exploit the thermal stability. Results of finite element analysis shows that the difference of the structural deflection in the front and rear guideways is less than $1.5{\mu}m$ due to symmetric design. The difference is less than $3.0{\mu}m$, even though the thermal deformation is considered. According to the performance evaluation, the radial error motion of the G/W spindle, which is measured by applying Donaldson Ball Reversal, is about 1.1${\mu}m$. The yaw error of the G/W slide is improved from 2.1 arcsec to 0.5 arcsec by readjusting the slide preload and ball screw.

• Structural Engineering and Mechanics
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• 제59권2호
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• pp.227-241
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• 2016

A circular plate with constant thickness, finite radius and stiff edge lying on an elastic halfspace is considered. The half-space consists of a soft functionally graded (FGM) layer with arbitrary varying elastic properties and a homogeneous elastic substrate. The plate bends under the action of arbitrary axisymmetric distributed load and response from the elastic half-space. A semi-analytical solution for the problem effective in whole range of geometric (relative layer thickness) and mechanical (elastic properties of coating and substrate, stiffness of the plate) properties is constructed using the bilateral asymptotic method (Aizikovich et al. 2009). Approximated analytical expressions for the contact stresses and deflections of the plate are provided. Numerical results showing the qualitative dependence of the solution from the initial parameters of the problem are obtained with high precision.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.182-184
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• 2009

• Journal of Mechanical Science and Technology
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• 제14권12호
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• pp.1328-1336
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• 2000

• 한국구조물진단유지관리공학회 논문집
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• 제15권5호
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• pp.160-168
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• 2011

성수대교 삼풍백화점 붕괴사고 등을 계기로 유지관리 분야의 중요성이 대두되면서 1995년 시설물의안전관리에관한특별법이 제정되어 점검 진단이 실시되는 등 본격적인 유지관리체제가 시작됐다. 그러나 점검 진단의 역사가 일천한 관계로 점검 진단에 대한 기술수준이 낮았고 연구 성과 또한 미흡하여 부실 점검 진단에 대한 우려가 상존해 있었다. 이에 2002년 평가제도가 도입되면서 부실 점검 진단 비율이 지속적으로 낮아져 왔다. 그러나 최근 점검 진단 실시결과 평가실적에 따르면 향후 부실 점검 진단비율이 더 이상 낮아지기 힘든 경향을 보이고 있다. 이를 계기로 부실 점검 진단과 관련하여 관련기관의 설문조사와 메커니즘 측면에서 고찰하므로서, 부실 점검 진단이 초래되는 근원적인 문제점을 나열하였고, 이를 바탕으로 현행 평가제도의 개선방향을 제시 하고자 하였다.

• 천문학논총
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• 제22권3호
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• pp.55-61
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• 2007

The KASINICS (Korea Astronomy and Space science Institute Near Infrared Camera System) is a ground-based near-infrared (NIR) imaging instrument. KASINICS has offner relay optics to reduce unwanted infrared light. For the offner optics, we adopted an ultra precision machining process which is installed at KBSI (Korea Basics Science research Institute). Since the offner relay optics is made of aluminum 6061 metal material, we did several tests to reach the specification. We found that a 0.497mm radius nose bite and 220m/min machining speed are best tool and condition to make this offner optics with the precision machine. In this paper, we report the technical method of ultra precision machining and results of the KASINICS offner optics.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.269-274
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• 2022

We prepared carbon nanotube (CNT) paper by a vacuum filtration method for the use of a chip-typed resistor as a precision passive device with a constant resistance. Hybrid resistor composed of the CNT resistor with a negative temperature coefficient of resistance (T.C.R) and a metal alloy resistor with a positive T.C.R could lead to a constant resistance, because the resistance increase owing to the temperature increase at the metal alloy and decrease at the CNT could counterbalance each other. The constant resistance for the precision passive devices should be maintained even when a heat was generated by a current flow resulting in resistance change. Performance reliabilities of the CNT resistor for the precision passive device applications such as electrical load limit, environmental load limit, and life limit specified in IEC 60115-1 must be ensured. In this study, therefore, the rated power determination and T.C.R tests of the CNT paper were conducted. -900~-700 ppm/℃ of TCR, 0.1~0.2 A of the carrying current capacity, and 0.0625~0.125 W of the rated power limit were obtained from the CNT paper. Consequently, we confirmed that the application of CNT materials for the precision hybrid passive devices with a metal alloy could result in a better performance reliability with a zero tolerance.