• Journal of Korean Neurosurgical Society
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• v.40 no.6
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• pp.471-475
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• 2006

Complete vertebral tumor resection is important in order to prevent local recurrence. Among the available techniques for total spondylectomy, the total en bloc spondylectomy has been accepted as the most sophisticated one. After a total en bloc spondylectomy, anterior and posterior column reconstruction is mandatory in order to achieve stability. We experienced the usefulness of an expandable cage for anterior column reconstruction especially in this surgery. The chance of cutting the nerve root and damaging the spinal cord is minimized because the size of the expandable cage is initially small enough to be inserted into the anterior column. The technical details of total vertebral body replacement with an expandable cage after an en bloc lumbar spondylectomy are described herein.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.21-27
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• 2020

The importance of floating photovoltaic systems has recently been emerging to address some issues arising from the installation of conventional ground-mounted photovoltaics. Floating photovoltaics have a few advantages such as cutting down land usage, reducing water evaporation or creating algae. Though there is still necessity to supplement with technical issues: mechanical stability, reliability and long-term durability of floaters and modules. In this paper, we focus the current level of packaging development and introduce research trends that could be applied to next-generation floating photovoltaics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.971-974
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• 2001

In this study, the static and dynamic characteristics of endmilling process was modelled and the analytic realization of chatter mechanism was discussed. In this regard, We have discussed on the comparative assessment of recursive time series modeling algorithms that can represent the machining process and detect the abnormal machining behaviors in precision endmilling operation. In this study, simulation and experimental work were performed to show the malfunctional behaviors. For this purpose, new recursive(RLSM) were adopted for the on-line system identification and monitoring of a machining process, we can apply these new algorithms in real process for detection of abnormal chatter. Also, the stability lobe of chatter was analysed by varying parameter of cutting dynamices in regenerative chatter mechanics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.269-273
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• 1997

In order to maker unmanned machining systems with satisfactory performances, it is necessary to incorporate appropriate condition monitoring systems in the machining workstations to provide the required intelligence of the expert. This paper deals with condition monitoring for chatter, tool wear and fracture during turning operation. To develop economic sensing and identification methods for turning processes, sound pressure measurement and digital signal processing technique were proposed. We suppressed chatter by stability control methodology, which was studied through manipulation of spindle speeds regarding to chatter frequencies. It was shown that tool wear and fracture were identified and to be estimated by using the wear indices. The validity of the proposed system was confirmed through the large number of cutting tests.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.5
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• pp.31-37
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• 2011

For the domestic glasses industry to procure competitiveness in the world CA(Cellulose Acetate) frame of spectacles market, CNC machining system for CA frame including high-value added CA cutting technologies should be developed with new materials for the rim based on Cellulose and sheet manufacturing base. The spindle system of glasses frame equipment that is the core to the quality of CA frame is the key technologies to realize high-speed, high-precision so its importance is remarkably emerging. In the study, at the structural design of the high spindle system of the private equipment for CA glasses frame embedded a motor of 40,000rpm, the stability of design was analyzed and investigated through selecting lubrication structure and thermal characteristics of the spindle system.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.263-268
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• 2001

The needs for precision machining of micro to milli parts have been increased as the industry require high quality products, especially for the micro-machining of IT products. The ultra-precision machining system is essential for the micro machining of fine structures, which insures machining accuracy, low systematic and random error and repeatability. In this study, we developed micro machining system, which is equipped with air bearing stage for ultra precision machining and also we present the results of V-grooving experiments, conducted by the developed system, to verify the performance of system. The results show that the machined V-grooving had good accuracy with repeatable stability.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.4
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• pp.23-28
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• 2003

This paper describes the machining characteristics of a developed micro grooving machine. Experiments have been conducted on the various grooving condition such as spindle revolution speed, feed rate and depth of groove. V and U-shaped blade tool and STD11 workpiece was used in this study. To evaluate the developed micro grooving machine, AE signal obtained from each experimental condition was analyzed, and cutting stability was compared with the surface state. As a result this study presented the process to optimize grooving condition and possibility of application of AE technique in groove machining.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.27-32
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• 2001

This paper deals with the study on the culling characteristics in ball-end milling process. First of all, the effects of the geometric cutting conditions such as the spindle speed, feedrates on the surface integrity and machining stability were evaluated by the analytical and the experimental approaches. A large amount of experimental sets are performed to evaluate the effects of chatter phenomenon on the machined surface. The optical microscope and the surface roughness measuring machine are used to measure the surface integrity and roughness of the machined surfaces.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.279-282
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• 2002

With the development of industrial society, the interest of new material is growing even in machining center. Composite materials in the new materials are superior to the metals In measure stability of strength, modulus and heat, moreover when mould is prepared, it can be done net shape manufacturing so it can be used widely in all sorts of machine parts, interior materials of car structural construct ions, the space aerial industry, ship materials, sports goods and so on. Therefore in this study, the property of processing drill on CFRP in composite materials by experimental study and some problems were examined.

• Journal of Welding and Joining
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• v.35 no.2
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• pp.1-5
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• 2017

Many microelectronic devices are miniaturizing the capacitance density and the size of the capacitor. Along with this miniaturization of electronic circuits, tantalum (Ta) capacitors have been on the market due to its large demands worldwide and advantages such as high volumetric efficiency, low temperature coefficient of capacitance, high stability and reliability. During a tantalum capacitor manufacturing process, arc welding has been used to weld base frame and sub frame. This arc welding may have limitations since the downsizing of the weldment depends on the size of welding electrode and the contact time may prevent from improving productivity. Therefore, to solve these problems, this study applies laser spot welding to weld nickel (Ni) and Au-Sn-Ni alloy using CW IR fiber laser with lap joint geometry. All laser parameters are fixed and the only control variable is laser irradiance time. Four different shapes, such as no melting upper workpiece, asymmetric spherical-shaped weldment, symmetric weldment, and, excessive weldment, are observed. This shape may be due to different temperature distribution and flow pattern during the laser spot cutting.