• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.210-215
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• 1998

본 연구는 핫셀(Hot-cell)에서의 활용을 전제로 핵연료 봉단용접기술로 개발되고 있는 래이저(Laser) 용접기술을 핵연료봉 퍼복재인 Zircaloy-4에 적용하여 그 용접성에 대한 기초적 특성을 분석하고, 관련 용접변수들의 용접성에 미치는 영향을 알아보고자 하였다. 사용된 용접기는 평균출력 150W급인 펄스형 Nd:YAG 레이저 용접기였으며, 보호가스 (shielding gas) 종류와 유량(flow rate), 용접속도(travel speed), 초점위치(focus position), 빔 파워(beam power), 시편의 표면거칠기(specimen surface roughness) 등의 용접변수가 용입 깊이와 용접비드 폭, 기계적 특성, 그리고 용접결함에 미치는 영향을 조사하였다. 그 결과 용접변수로 범 파워 125W이상, 초점위치 2mm, 그리고 보호가스로는 He가스가 적절하였으며, 시편의 표면거칠기가 거칠수록 용입깊이가 깊었다. 본 연구를 통해 핵연료봉 피복재 Zircaloy-4의 레이저 용접시 신뢰성 있는 용접조건을 확립하기 위한 기초자료를 얻을 수 있었다.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.151-158
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• 2005

Micro-machine tool is essential in the micro/meso cutting for the sake of saving of space, resources, and energy. In this research, a micro-turning lathe was fabricated with piezoelectric feed drive mechanism, and motion of each axis was generated by stepwise mechanism with two piezo actuators. The resolution to drive the axis was $0.05{\mu}m$ and position accuracy less than $2{\mu}m$ was assured. From the positioning experiment, piezo feed mechanism is good enough for the micro machine tools. Many fuming experiments were carried out with diamond-cutting tools to evaluate cutting capability of a machine tool. Continuous flow type chip could be obtained even if the cutting speed was very low due to small diameter of workpiece. However, thorough investigation about machineability in micro/meso cutting is inevitable to assure high quality surface roughness in micro machine tool.

• Journal of Korean Society of Steel Construction
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• v.8 no.3 s.28
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• pp.151-160
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• 1996

The fatigue test under the constant amplitude repeated loading is performed to investigate the fatigue behavior of the Torque Shear type high tension bolted joint which is able to manage the axial force uniformly. From the test results, it's known that the reduction of the axial force of T/S bolt followed by the elasped time is similar to that of the high tension bolts. The difference of relaxation is not occurred according to the position of bolts, the size of the introduced axial force but the effect of the variation of temperature is large. In the reduction of the axial force followed by the cumulation of the fatigue load, the outer bolt is larger than the inner bolt. This result depends on the difference in the distribution of the non-slip zone. The variation of the surface roughness affects the slip and the reduction of the anal force.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.513-518
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• 2000

Surface roughness is one of the most important parameters to estimate quality of products. As this reason. so many studies were carried out through various attempts that were contact or non-contact using computer vision. Even though these efforts, there were few good results in this research. However, texture analysis is making a important role to solve these problems in various fields including universe, aviatiion, living thing and fibers. In this study, texture parameter was obtained by means of position operator according to variation of angle direction and distance. As a result, it was found that surface texture was more effected by direction then distance

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.59-65
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• 2006

The purposes of using cutting fluid during cutting have been cooling, lubricating, chip washing and anti-corroding. However, the present manufacturing industry restricts the use of cutting fluid because cutting fluid contains poisonous substances which are harmful to the human body. Therefore environmentally conscious machining and technology have more important position in machining process because cutting fluids have significant influence on the environment in milling process. In this study, environmentally conscious machining can be obtained by the way of selecting the optimum machinig conditon using the design of experiment. Cutting using oil-mist showed better cutting characteristics than dry, air and fluid cutting with respect to by cutting force, tool wear and surface roughness. Also, the optimum machining condition for cutting using oil-mist could be selected through Taguchi method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.50-57
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• 2006

The investigation of microscopic precision in high speed endmilling is necessary for machinability evaluation, and the environmentally conscious machining technology have more important position in recent machining process. The microscopic precision of workpiece is influenced by machining environments variation as cutting fluid type and lubricant method. In this study, the cutting forces according to variation of cooling and lubrication are investigated by specially designed tool dynamometer. And the surface roughness, micro hardness and residual stress are evaluated according to machining environment. The characteristics of damaged layer in environmentally conscious machining and conventional machining using cutting fluid are compared experimentally.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.20-28
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• 2003

The machinability of Ti-6Al-4V titanium alloy and tool wear behavior in machining of Ti-6Al-4V titanium alloy was studied to understand the machining characteristics. This material is one of the strong candidate materials in present and future aerospace or medical applications. Recently, their usage has already been broaden to everyday's commercial applications such as golf club heads, finger rings and many decorative items. To anticipate the general use of this material and development of the titanium alloys in domestic facilities, the review and the study of the machining parameters for those alloys are necessary. This study is concentrated to the machining parameters of the Ti-6Al-4V alloy due to their dominant position in the production of titanium alloys.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.361-366
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• 2000

The machinability of Ti-6Al-4V titanium alloy and tool wear behavior when machining Ti-6Al-4V titanium alloy was studied to understand the machining characteristics. this material is one of the strong candidate materials present and future aerospace or medical applications. Nowadays their usage has already been broaden to everyday's commercial applications such as golf club heads, finger rings and many decorative items. Anticipating the general use of this material and development of the titanium alloys in domestic facilities, the review and the study of the machining parameters for those alloys are deemed necessary. this study is concentrated to the machining parameters of the Ti-6Al-4V alloy due to their dominant position in the production of titanium alloys.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.4
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• pp.16-24
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• 1995

The milling process is one of the most important metal removal processes in industry. due to the complexities inherent to the cutter insert geometry and the milling cutter kinematics, these processes leave an analytically difficult to predict texture on the machined surface's hills and valleys. The instantaneous uncut chip cross sectional area may be estimated by the relative position between the workpiece and the cutter inserts. Furthermore, since the cutting forces are proportional to the instantaneous uncut chip cross sectional area, the cutting forces in face milling operations can not be estimated easily. A new simulation program which is based upon the numerical method has been proposed to estimate the cutting force components, with the ability to predict the machined surface texture left by the face milling.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.54-62
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• 2001

This paper describes a new method for measuring the changes in specific surface asperities arising from processes such as finishing, coating, wear and corrosion. In repetitive measurements, relocation device gives the same position and orientation so that specific profile can be obtained. A low-cost relocation device is designed and its performance is assessed. The error in relocation process is compensated by statistic compensation algorithm. And, a removing process of cusp by grinding is observed by the proposed method.