• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.304-312
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• 1999

In order to make industrial robots and CNC machine tools perform tasks efficiently, each axis has to be accelearated and decelerated appropriately. The existing techniques for the acceleration and deceleration of industrial robots and CNC machine tools are not efficient to generate velocity profiles. Thus, these previous techniques cannot generate velocity generating velocity profiles that cannot be generated by them. Based on the proposed approach, an acceleration and deceleration circuit for industrial robots and CNC machine tools is designed with a FPGA by using the VHDL.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.75-81
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• 1999

In order to remain competitive, a manufacturing company needs to maintain the optimal condition of its manufacturing system. Machine tools as an important element of a manufacturing system consist of complex mechanical as well as electronic components. Therefore, diagnosing the troubles of machine tools is a tricky process which requires a lot of experience and knowledge. Since providing machine tool users with necessary services at the right time is very difficult and expensive, a remote diagnosis system is to be regarded as a good alternative, with which users can diagnose and fix the machine troubles. This paper presents a framework for a remote machine tools diagnosis system by combining the world wide web technology and backward reasoning expert system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.899-904
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• 2001

The impact of PVD coatings can be summed up in practical terms: this technology historically complements the best designed tool substrates to enhance cutting performance. PVD coatings are now incorporated in 25% of all HSS tools. The functionality is to extend the machining speed range, improve wear resistance at the cutting edge, and reduce friction at chip/tool contact areas to allow easier chip evacuation. These translate to a larger safe zone, as discussed in the failure mode diagram, for better productivity and higher reliability in machining operations of the customer. PVD coatings therefore represent an enabling technology that extends the application range of cutting tools in response to modern industrial needs. PVD coatings prolong the product life cycle of HSS tools and help this "mature" material to hold its territory against the advent of the newer hardmetal and ceramic tool materials. There is a lot of competitive life left particularly in PVD coated HSS endmills, drills, threading/tapping tools. PM HSS technology further increases the possibilities.ibilities.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.5-11
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• 1994

We have investigated the variation of dwell and warm-up time for effects of positioning accuracy of the CNC machine tools with an laser measuring system. Also, we strdied the effect of improvement of the positioning accuracy by variation of the temperature for hollow ball screw, which mostly used as drive mechanism of CNC machine tools. We dbtained the effectiveness of cooling effect of the new cooling system, compared with the conventional cooling system.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.718-719
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• 2015

As a recent global trend, the majority of plant projects are delivered through EPC or EPC-turnkey contracts, where a contractor's liability is more complicated because of the mega size scale and financing method. Previous researches have been lacking a practical usability for project members for liabilities of contracts. Those were focused on solving the claims or schedule calculation issues only. The objective of the present study was to develop a validation process for LDs (liquidated damages) in contractor's liabilities with various case studies and expert judgments. As summarized in this paper, the processes and tools were developed with project life cycle process. The project preparation phase includes 3 step check lists to determine the Go or No-go for projects. In progress phase, contractors should focus on the response strategies for claims with liabilities. The study concludes that those developed processes and tools will help to manage risk of LDs for the contractors in the overseas projects.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1904-1909
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• 1991

Software linear and exponential acceleration/deceleration algorithms for control of machine axes of motion in industrial robots and CNC machine tools are proposed. Typical hardware systems used to accelerate and decelerate axes of motion are mathematically analyzed. Discrete-time state equations are derived from the mathematical analyses for the development of software acceleration/deceleration algorithms. Synchronous control method of multiple axes of motion in industrial robots and CNC machine tools is shown to be easily obtained on the basis of the proposed acceleration/deceleration algorithms. The path error analyses are carried out for the case where the software linear and exponential acceleration/deceleration algorithms are applied to a circular interpolator. A motion control system based on a floating point digital signal processor (DSP) TMS 320C30 is developed in order to implement the proposed algorithms. Experimental results demonstrate that the developed algorithms and the motion control system are available for control of multiple axes and nonlinear motion composed of a combination of lines and circles which industrial robots and CNC machine tools require.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.111-117
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models the thermal errors for error analysis and develops an on-the-machine measurement system by which the volumetric errors are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments show that the developed system provides a high measuring accuracy, with repeatability of $\pm$2$\mu\textrm{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be also improved by using the developed measurement system when the spherical ball artifact is mounted on a modular fixture.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.5
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• pp.500-505
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• 2012

Recently, a high speed spindle is an essential part of machine tools to satisfy latest demand of high precision product and machining of hard materials. But, there are many disadvantages such as heat generation of built-in-motor, bearing friction, noise, vibration and displacement because of the high speed. Many researches on spindle systems have been conducted for solving these problems. In this study, technical trend of machine tools spindle systems are analyzed with patent PSM, mapping and grouping. The analysis is carried out for the applied patent during January 2000 and December 2009 in Korea, Japan, EU and U.S.A. And development of the direction, strategy and promising technologies of the spindle system are suggested.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.9
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• pp.82-88
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• 2001

In order to fulfil the requirements of the various performance profiles of ceramic cutting tools, six different SiC-based ceramics have been fabricated by hot-pressing (SiC--${Si}_3 {N}_4$composites) or by hot-pressing and subsequent annealing (monolithic SiC and SiC-TiC composites). Correlation between the annealing time and the corresponding microstructure and the mechanical properties of resulting ceramics have been investigated. The grain size of both ${Si}_3 {N}_4$and SiC in SiC-${Si}_3 {N}_4$composites increased with the annealing time. Monolithic SiC has the highest hardness, SiC-TiC composite the highest toughness, and the SiC-${Si}_3 {N}_4$composite the highest strength among the ceramics investigated. The hardness of SiC-${Si}_3 {N}_4$composites was relatively independent of the grain size, but dependent on the sintered density. The cutting performance of the newly developed SiC-based ceramic cutting tools will be described in Part 2 of this paper.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.6
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• pp.422-433
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• 2015

In this paper, we demonstrate inter-layer prediction tools for scalable video coders. The proposed scalable coder is designed to support not only spatial, quality and temporal scalabilities, but also view scalability. In addition, we propose quad-tree inter-layer prediction tools to improve coding efficiency at enhancement layers. The proposed inter-layer prediction tools generate texture prediction signal with exploiting texture, syntaxes, and residual information from a reference layer. Furthermore, the tools can be used with inter and intra prediction blocks within a large coding unit. The proposed framework guarantees the rate distortion performance for a base layer because it does not have any compulsion such as constraint intra prediction. According to experiments, the framework supports the spatial scalable functionality with about 18.6%, 18.5% and 25.2% overhead bits against to the single layer coding. The proposed inter-layer prediction tool in multi-loop decoding design framework enables to achieve coding gains of 14.0%, 5.1%, and 12.1% in BD-Bitrate at the enhancement layer, compared to a single layer HEVC for all-intra, low-delay, and random access cases, respectively. For the single-loop decoding design, the proposed quad-tree inter-layer prediction can achieve 14.0%, 3.7%, and 9.8% bit saving.