• Journal of Korea Trade
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• 제26권3호
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• pp.102-116
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• 2022

Purpose - This paper empirically investigates the relationship between firm productivity and importing intermediate inputs in the Korean manufacturing sector. Design/methodology - This paper tests the two related hypotheses on the relationship between importing and productivity for a sample of Korean manufacturing firms. We test the self-selection hypothesis by comparing pre-entry levels of productivity between importers and non-importers. We test the learning-by-importing hypothesis by employing propensity score matching with differencein-differences approach. Findings - Future importers are more productive than future non-importers years before they start to import, which supports the self-selection hypothesis. In contrast, there is no strong evidence for learning-by-importing. Originality/value - This paper is the first study to explore the relationship between importing and firm-level productivity for Korean firms. The results have an important implication on trade policies to lower or raise trade barriers in imported inputs.

• The Journal of Asian Finance, Economics and Business
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• 제9권1호
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• pp.35-42
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• 2022

The paper aims to examine the impact of exports on the growth of Vietnamese manufacturing small and medium-sized enterprises (SMEs) by exploring the information of 36,053 enterprises across 24 manufacturing sectors from the Vietnam Annual Enterprise Survey (VAES) in the period 2014-2019. To deal with the problem of variable variance, autocorrelation, and endogeneity of the model, the paper uses the OLS regression method with a strong standard error method and system GMM. Export participation by SMEs is positively associated with business growth in terms of sales and total assets, according to the findings. The GMM estimate shows that the rate of sales growth among exporters is 36.5 percent greater than that of non-exporting enterprises in the case of the sales growth measure. Exporters' average total asset growth rate is 19% greater than the rate estimated for non-exporting businesses. The study's findings indicate the need of adopting policies that promote SMEs in transition economies like Vietnam to engage in exporting activities. Furthermore, the findings show that financial assistance and suitable ownership would enable SMEs to take advantage of export opportunities to increase sales and total assets.

• 한국생산제조학회지
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• 제23권5호
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• pp.435-442
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• 2014

This paper describes an improved design model that can be used to configure a non-contact pneumatic device to turn a large sheet at the in-line system. For rotational moving in the conveyor system, the conventional method is to turn the system itself. The improved non-contact pick-up system mainly uses 8 pairs of L-shaped latches and 12 swirl type heads. It is positioned above the upward air flow table. This system performs the non-contact gripping and side-edge contact support in the vertical and rotational directions to hold the self-weight of a large flat sheet. A non-contact air head can exert a sufficient gripping ability at 4N lower than the standard working pressure. The side latches support 60% of the lifting force required. Through structural and flow analysis, the working conditions were simultaneously considered in accordance with the deflection and flatness of the glass.

• 한국기계가공학회지
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• 제15권3호
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• pp.36-43
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• 2016

Carbon fiber-reinforced silicon carbide (Cf-SiC) and SiC / SiC composites have high thermal conductivity, and excellent corrosion and wear resistance, a low coefficient for thermal expansion and are lightweight. This is why they are commonly used in parts of the aerospace industry to develop an aircraft thrust deflector, jet vane, combustion chamber, elevens, body flap, and a shingle. So, understanding how this state-of-the-art Cf-SiC affects both internal and external crack detection and determining issues during the manufacturing process of composite materials, should be evaluated according to valuation techniques in the external environment. In this paper, we apply a non-contact air ultrasonic technique of non-destructive testing techniques to perform a study on internal defect detection identification and assessment of carbon-fiber reinforced silicon carbide composites to perform basic research and applied research.

• 품질경영학회지
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• 제14권1호
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• pp.11-18
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• 1986

Whereas in non-symmetrical distribution manufacturing process they are not plotted relatively on the centeral line but plotted on the skew of right-hand side or left-hand side. That is to say, for the prupose of producing either upper-specification-oriented items or lower-specification-oriented items, and when we carry out tighter control so as to have them pass only its specifications, the distribution shape naturally has a non-normal distribution. In these cases, we could use either compressed control limits or variable transformed logarithm control charts. It the above mentioned methods were not available, we should use special purpose control chart-Mode control chart or Gram-Charlier control chart. These are proper methods for manufacturing process control which uses control chart method. In spite of these methods, domestic manufacturing and mining companies are utterly ignorant about these methods. That invites practical problems in their companies. To enhance this improvements, I proved the property of practical applications of control chart method by comparing and analyzing the case studies of practical application of speical purpose control chart method, and also by introducing the application methods.

• 대한안전경영과학회지
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• 제17권1호
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• pp.131-137
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• 2015

Last five years, Occupational injury rate is declining but still a standstill as 2%, if the rate of deaths all people from 2% to 1% in 2013, but decreased as, occupational safety and health in terms industrial accidents yet has a very weak structure in very small Manufacturing workplace. The purpose of this study was to survey a 1:1 directly person interviews with a structured questionnaire intended for 150 a very small manufacturing workplace. In the results, working with non-regular(informal) workers is one in 10 persons 11.7% and female workers is about three people on 10 persons with 31.0%, and that 75% of non-regular workers who are mainly engaged in the production line appeared. And the work-related injury and accident experience was 4.0% and the occupational injury rate was 1.24%, especially occupational injury rate of older workers was 3.65%, a female workers 1.72%. Workplace risk assessment carried out in response that it was very low as 9.3% of the total. In the technology and funding programs that are supported by the government, was highest with 62.7% of the clean support program awareness, awareness of the rest of the programs is about 10-14% lower. And the satisfaction of supporting a clean support program were the highest 81.3%.

• International Journal of Precision Engineering and Manufacturing
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• 제4권3호
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• pp.36-41
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• 2003

This paper describes a numerical analysis of a non-steady state porthole die extrusion, which is useful for manufacturing long tubes with a hollow section. Materials divided through several portholes are gathered within a chamber and are then welded under high pressure. This weldability classifies the quality of tube products and is affected by process variables and die shapes. However, porthole die extrusion has been executed based on the experience of experts, due to the complicated die assembly and the complexity of metal flow. In order to better assist the design of die and to obtain improvement of productivity, non-steady state 3D FE simulation of porthole die extrusion is required. Therefore, the objective of this study is to analyze the behavior of metal flow and to determine the welding pressure of hot extrusion products under various billet temperatures, bearing length, and tube thickness by FE analysis. The results of FE analysis are compared with those of experiments.

• 대한안전경영과학회지
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• 제14권2호
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• pp.193-204
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• 2012

This paper deals with an empirical analysis of the structural relationship among the factors such as quality management activities, organizational learning and firm performance of manufacturing corporations. The findings of the analysis are expected to make lots of contribution to manufacturing corporations establishing strategies for quality management activities and organizational learning. From the analysis, following conclusions and suggestions could be drawn: First, an analysis of the relationship between quality management activities and organizational learning showed that most activities of quality management turned out to exercise great influence upon the factors of organizational learning. This means that the activities of quality management will prompt the members of an organization to actively engage in learning activities individually, by team and organizationally, motivating them to spread such activities across the whole organization, leading ultimately to fundamental renovation of the very organization. Second, from an analysis of the relationship between organizational learning and firm performance, that is, financial and non-financial performances of a company, it was found that most factors of organizational learning have tremendous impact upon financial and non-financial performances of the company. Such result implies that decision and management of the things to be performed in the process of organizational performances are essential to determining firm performance because firm performance depend largely on the outcomes of organizational learning.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.144-149
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• 2022

A cryogenic Mixed Refrigerant Joule-Thomson refrigeration cycle was designed to be applied to the semiconductor etching process with non-flammable constituents. 3-stage cascade refrigerator, single mixed refrigerant Joule-Thomson refrigerator, and 2-stage cascade type mixed refrigerant Joule-Thomson refrigerator are analyzed to figure out the coefficient of performance. Non-flammable mixture of argon(Ar), tetrafluoromethane(R14), trifluoromethane (R23) and octafluoropropane(R218) were utilized to analyze the refrigeration cycle efficiency. The designed refrigeration cycle was adapted to cool down the coolant of HFE7200(Ethoxy-nonafluorobutane, C₄F₉OC₂H₅) with certain constraints. Maximum coefficient of performance of the refrigeration system is obtained as 0.289 for the cooling temperature lower than -100℃. The detailed result of the coefficient of performance according to the mixture composition is discussed in this study.

• 한국기계가공학회지
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• 제21권6호
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• pp.74-80
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• 2022

The surface status of a workpiece determines its functionality, product quality, and manufacturing costs. Thus, several finishing technologies have been widely investigated and applied to improve surface characteristics. In this study, rotational electro-magnetic abrasive finishing (REMAF) was suggested as a non-contact finishing process to achieve high geometric precision. To verify the effects of the REMAF process on burr removal on the surface of Al6061, experiments were conducted using the Taguchi method. Based on the experimental results analyzed by the S/N ratio and ANOVA, the optimal conditions were defined as A₃B₂C₃D₃ that corresponded to 1,800 rpm of rotational speed, 1.5 kg of abrasive particle weight, 0.7 mm of abrasive diameter, and 15 min of working time. In addition, the particle weight was a key attribute for deburring, whereas the working time was less effective.