• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.245-250
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• 2002

A successful on-line monitoring system for conventional machining operations has the potential to reduce cost, guarantee consistency of product quality, improve productivity and provide a safer environment for the operator. In fee-shape machining, typical signs of tool problems such as vibration, noise, chip flow characteristics and visual signs are almost unnoticeable without the use of special equipment. These characteristics increase the importance of automatic monitoring in fine-shape machining; however, sensing and interpretation of signals are more complex. In addition, the shafts of the micro-tools break before the typical extensive cutting edge of the tool gets damaged. In this study, the existence of a relationship between the characteristics of the cutting force and tool usage was investigated, and tool breakage detection algorithm was developed and the fellowing results are obtained. In data analysis, didn't use a relative error compare which mainly used in established experiment and investigated tool breakage detection algorithm in time domain which can detect AE and cutting force signals more effective and accurate.

• 한국생산제조학회지
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• 제22권3호
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• pp.437-446
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• 2013

There have been numerous studies on end milling processes. However, these have been restricted to the application of tools for special cutting purposes. A side milling cutter can handle long, deep, and open slots in a more efficient manner, and it provides the best stability and productivity for this type of milling. In this paper, a method to predict the cutting forces in side milling is described, and simulated cutting forces are compared with those obtained by cutting experiments. In particular, the side milling process easily generates relative motion between the tools and the workpiece because it produces intermittent cutting forces that cause vibrations over a wide frequency range. Therefore, the application of a dynamic cutting model instead of a static cutting model is appropriate to forecast the cutting forces more accurately.

• 한국경영과학회지
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• 제23권2호
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• pp.201-217
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• 1998

This paper attempts to show how DEA(data envelopment analysis), a nonparametric productivity analysis method, can be employed for insurance companies to improve their respective efficiencies and competitiveness. Specifically, we measured relative technical efficiencies and returns to scale of 11 Korean property-liability insurance companies using BCC model, and raised several issues including the cause of inefficiency, benchmarking toward reference set and resource allocation concerning the insurance companies. Also, in order to monitor the variability of the research results over periods, we employed longitudinal analysis to see the moving patterns of technical efficiencies, returns to scale and frequencies included in the reference set of the individual insurance companies under consideration. The methodology and the results in this paper may also serve as a useful guideline for individual insurance companies to set their respective business strategies.

• 한국정밀공학회지
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• 제13권10호
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• pp.71-77
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• 1996

This paper describes the development of on the machine measuring(OMM) system which can directlry measure the three dimensional machined dimensilnal accuracy using scanning probe in milling machine. Two algolithms, continuous path(CP) measurement using UC program and CAD data assisted point to point(PTP) measurement, were developed regarding specification of scanning probe. The OMM system was contructed to verify the developed system suing the proposed algorithm, and actually measured three kinds of machined TV shadow mask molds. The developed system was evaluated it's repeatability and compared with the current measurement system of CMM(Coording Measuring Machine) in terms of relative accuracy and time reduction and productivity increase.

• 한국경영과학회지
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• 제34권4호
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• pp.1-14
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• 2009

This study empirically tests post-M&A performance through competitiveness variables based on extensive firm-based panel data over the past 26 years in the world steel industry. Different measures of profitability, productivity, efficiency, market share, and growth rate which are considered as critical factors of competitiveness are used in the analysis. In particular, this paper tries to separate M&A samples into two cases; horizontal integration (between steel makers) and vertical integration (between steel makers and iron ore suppliers/steel consuming firms). Merged firms show significant improvement in competitiveness relative to other individual firms in the steel industry.

• 한국의상디자인학회지
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• 제3권2호
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• pp.137-160
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• 2001

A study on the structural change in the U.S. textile industry. The U.S. textile industry has undergone significant changes over the last fifty years, including a steady decline in the relative scale of domestic production, employment reduction, and increased competition from imported products. In order to weather a crisis, the responses of the U.S. textile industry have been made such as investment in technology, specalization in the textile and apparel industries. The textile and apparel industries have taken steps to increase labor productivity through automations to speed management to create and introduce new products and new methods, and have lowered indirect overhead costs. Regarding these response of the U.S. and other situation of world textile and apparel trade market, much of the sense of crisis that pervades korean textile and apparel industries has to do with the problem of adjusting corporate policy.

• 한국정밀공학회지
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• 제7권1호
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• pp.53-62
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• 1990

High speed and heavy cutting performed for improving the surface quality and productivity, are often prevented due to chatter phenomena. Chatter is a violent relative vibration between workpiece and tool in machining of metals, and is an important limiting factor of production rate and surface quality, and reduces the tool life and the dynamic performance of machine tool itself. In this study, in order to suppress the chatter, a modified tool-post combined with the spring and damper was designed and used in the actual cutting test. The results of this study are summerized as follows; The spring and damper adopted in the modified tool-post have the suppressing effects of chatter, and there exists an optimum combination between spring constant and damping ratio.

• 전기학회논문지P
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• 제61권1호
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• pp.55-58
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• 2012

By using EEG and HRV, subjects were estimated on their psychological and physiological reaction when reading psychrometric chart in 7 point century font, in an environmental test room in the condition of temperature 25[$^{\circ}C$], relative humidity 50[RH%], air current speed 0.02[m/sec], giving variation in illuminance to 0.1, 300, 600, 1000, 1300 and 1600[lux]. As a result, it was at 1300[lux] that absolute ${\alpha}$ wave, SMR, SDNN were most vitalized, and also both sides ${\alpha}$ wave asymmetry index, SEF50, HRT, stress and fatigue degree were at the lowest. It was found that a certain illuminance which minimizes psychological stress and fatigue degree while enhancing concentration and task achievement stably does exist.

• 품질경영학회지
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• 제38권3호
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• pp.393-407
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• 2010

The purpose of this study is to analysis relative efficiency and efficiency in process of time. Thus we use panel data of 34 local public medical centers between 2003 and 2005 to use DEA and Malmquist analysis. The result of our this study is as flow; first, The results of static efficiency of 34 local public medical centers show 10 CCR model and 23 BCC model which is difference of efficiency by economic of scale. Second, a cause of increased efficiency is not only change of technology but also change of efficiency to management system index show between 2003 and 2005 by Malmquist analysis and contracting-out is higher than direct management between 2004 and 2005. That means efficiency of local public medical centers is their own effort and innovation not government subsidies.

• Asian Journal of Innovation and Policy
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• 제7권1호
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• pp.30-54
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• 2018

Tech start-ups and their ecosystems are gaining increasing prominence globally and so are in India, due to their potential to contribute to employment generation, innovations, productivity, national income and exports. Against this backdrop, this article analyzes the key characteristics of tech start-ups relative to traditional start-ups and modern start-ups in India. Further, the salient features of tech start-up promotion policies initiated by the government of India and government of Karnataka as well as the current regional and sectoral distribution of start-ups is elucidated. Subsequently, the structure and components of entrepreneurial ecosystems currently under evolution in the metro cities of India are examined. Finally, the key factors contributing to the growth of different ecosystem components and its implications for the future growth of tech start-ups are outlined.