중국의 기업규모와 경제성장-중국 공업 기업 데이터에 기초한 실증분석

학위논문 (석사)-- 서울대학교 대학원 : 경제학부, 2014. 8. 이근.A vast amount of literature is available on the determinants of economic growth and development, and many factors and variables have been suggested theoretically and empirically. Numerous studies have investigated the role played by big businesses as well as small and medium enterprises (SMEs) in promoting economic growth. All of these studies suggest that the net influence of firm size on macroeconomic performance is an important yet unresolved empirical question. In China, the linkage between firm size and economic growth remains unexplored, and no study has examined the entire spectrum of firm size to explore the development dynamics of China. To fill this research gap, this paper presents exploratory empirical evidence based on provincial-level data obtained from 2004 to 2009 in China. We measure firm size in terms of relative sales, relative number of these firms, or absolute number of firms of different sizes in each province. The empirical results of all of the models consistently show three major patterns. First, big businesses have a significant and negative effect on economic growth, medium-sized firms have an insignificant effect on economic growth, and small firms have a significant and positive effect on economic growth. Second, the average size of big businesses and SMEs has a positive effect on economic growth, whereas the number of firms of different size exerts a negative effect on the economy. The average size of various size groups of enterprises, rather than the number of firms, is important in Chinas economy. Third, differences in efficiency translate to differences in contribution. Disparity in efficiency exists among large, medium, and small enterprises. This disparity is the primary cause of the performance gap in China.1. Introduction and existing literature 1.1. Motivation 1.2. Existing literature 1.3. Comparison with other countries 1.4. Difference in efficiency 2. Research methodology 3. Data 3.1. Measures of large, medium and small enterprises 3.2. Variables used in the regressions 4. Empirical Results 4.1. The bench mark model 4.2. Robustness test 5. What is changing growth engine in China? 5.1. Number and size measures 5.2. The absolute number of firms versus the average size of firms 5.3. Robustness test 6. Conclusions ReferencesMaste

교정용 브라켓의 형태와 슬롯 각도에 대한 구강스캐너의 정확성 평가

Through the dental model acquired at the time of re-diagnosis of patients undergoing orthodontic treatment, not only the relationship between the entire dentition and the arch, but also the position of the bracket is reevaluated. To evaluate whether the bracket prescription is accurately expressed by checking the height, position, and angle of the bracket slot can help to produce a good treatment result. Orthodontic tooth movement can also be easily evaluated using IOS. The purpose of this study was to evaluate the accuracy of digital scan images of brackets produced by 4 IOSs when scanning the surface of dental model attached with different bracket materials (metal, ceramic, resin, resin bracket with metal slot). The images scanned with a laboratory scanner and images taken with a scanning electron microscope were used as references. Each bracket axis was set in the reference image, and the axis was set identically by superimposing with the IOS image, and then only the brackets were divided to perform quantitative and qualitative analysis. By quantitative analysis, precision and trueness were analyzed as RMS values and calculated maximum discrepancy. By qualitative analysis, the bracket wing was divided into 4 parts; upper-mesial, upper-distal, lower-mesial, and lower-distal to confirm the frequency of error more than 20 ㎛. For the bracket slot, the slot base angle and the parallelism of the slot wall were measured. The results of this study are as follows. 1. There were significant differences in the scanning accuracy of the bracket according to the type of scanner. In quantitative analysis, precision RMS was the smallest in Trios 3, followed by Primescan, CS3600, and i500 (P <0.001). Trueness RMS was smallest in Trios 3, followed by Primescan, i500, and CS3600 (P <0.001). The maximum discrepancy was the smallest in Trios 3, followed by Primescan, CS3600, and i500 (P <0.001). 2. There were significant differences in the scanning accuracy of the bracket according to the type of brackets. In the qualitative analysis, the scan accuracy of the bracket wing was the smallest in Trios 3, followed by Primescan, CS3600, and i500 (P <0.001). The parallelism measured by the difference between the upper and lower angles of the slot wall was 0.48 in SEM, 7.00 in Primescan, 5.52 in Trios 3, 6.34 in CS3600, and 23.74 in i500 (P <0.001). The difference between the manufacturer's torque and the bracket slot base angle was 0.39 in SEM, 1.96 in Primescan, 2.04 in Trios, and 5.21 in CS3600 (P <0.001). 3. The maximum discrepancy according to the bracket materials was the lowest in ceramic, followed by metal, resin and resin bracket with metal slot (P <0.05). In the qualitative analysis, the scan accuracy of the bracket wing was lower in resin and resin metal brackets than in ceramic and metal (P <0.05). Brackets that are more translucent and transmit light, such as resin or resin brackets with metal slots, tended to show greater errors than metal or polycrystalline ceramic brackets. This study evaluated the accuracy of the bracket only. According to the results of this study, it was possible to confirm the bracket slot base angle, which is difficult to obtain by the conventional impression method according to the scanner type. However, it must be admitted that there is some error in recognizing slots through scanning in general. Considering only the scan of the bracket in this study, Primescan and Trios 3 were more accurate among the 4 types of IOSs, Primescan, Trios 3, CS3600, and i500. Among the brackets, it should be noted that the polycrystalline ceramic bracket, which has less reflection or absorption of light when using the scan, has high accuracy, and there is more error when using other types of brackets.open박