• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.4 s.247
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• pp.306-313
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• 2006

Automated material handling system is being used as a method to reduce manufacturing cost in the semiconductor and flat panel displays (FPDs) manufacturing process. Those are considering switch-over from the traditional cassette system to single-substrate transfer system to reduce raw materials of stocks in the processing line. In the present study, the wafer transportation speed has been evaluated by numerical and experimental method for three propulsion nozzle array (face, front, rear) in an air levitation system. Test facility for 300 mm wafer was equipped with two control tracks and a transfer track of 1,500mm length. The diameter of propulsion nozzle is 0.8mm and air velocity of wafer propulsion is $50\sim150m/s$. We found that the experimental results of the wafer transportation speed were well agreed with the numerical ones. Namely, the predicted values of the maximum wafer transportation speed are higher than those values of experimental data by 16% and the numerical result of the mean wafer transportation speed is higher than the experimental result within 20%.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.689-692
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• 2008

Noises from ceiling mounted air-conditioning units were recorded in various actual situations such as offices, classrooms and libraries. Eight specimens of air-conditioners from major domestic and foreign manufacturers' were investigated in this study. A head and torso simulator was located 1.5 m beneath the air-conditioner panel for the measurements and sound pressure levels of the recording sounds were varied from 28 to 55 dBA with 3 dB steps for subjective evaluations. A total of 88 stimuli was randomly presented to subjects using a headphone system in semi-anechoic chamber. Two-categorized (noisiness and amenity) nine-point scale was used as evaluation method. The third scale ('point 3') among the nine-point scale was set as the threshold of allowable level of the air-conditioning sounds in consideration of the real situations. The results indicate that the allowable sound pressure level is around 34 dBA for both noisiness and amenity categories.

• Smart Structures and Systems
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• v.14 no.4
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• pp.569-594
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• 2014

Damage detection methods based on modal analysis have been widely studied in recent years. However the calculation of mode shapes in real structures can be time consuming and often requires dedicated software programmes. In the present paper the combined application of proper orthogonal decomposition and gapped smoothing method to structural damage detection is presented. The first is used to calculate the dynamic shapes of a damaged structural element using only the time response of the system while the second is used to derive a reference baseline to which compare the data coming from the damaged structure. Experimental verification is provided for a beam case while numerical analyses are conducted on plates. The introduction of a stiffener on a plate is investigated and a method to distinguish its influence from that of a defect is presented. Results highlight that the derivatives of the proper orthogonal modes are more effective damage indices than the modes themselves and that they can be used in damage detection when only data from the damaged structure are available. Furthermore the stiffened plate case shows how the simple use of the curvature is not sufficient when analysing complex components. The combined application of the two techniques provides a possible improvement in damage detection of typical aeronautical structures.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.15-20
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• 2004

In order to evaluate spring-back behavior in automotive sheet forming processes, a panel shape idealized as a double S-rail has been investigated. After spring-back has been predicted for double S-rails using the finite element analysis, results has been compared with experimental measurements for three automotive sheets. To account for hardening behavior such as the Bauschinger and transient effects in addition to anisotropic behavior, the combined isotropic-kinematic hardening law based on the Chaboche type model and a recently developed non-quadratic anisotropic yield function have been utilized, respectively.

• KDI Journal of Economic Policy
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• v.39 no.1
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• pp.1-18
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• 2017

This paper empirically studies the effect of public procurement on small and medium-sized enterprises (SMEs) in the Republic of Korea using firm-level data. Public procurement, the purchase of goods and services from private firms by the public sector, is regarded as an important policy measure for providing support to firms, particularly SMEs. This study uses establishment-level panel data of the mining and manufacturing sectors from the Korean National Bureau of Statistics (Statistics Korea) and procurement history from the Korean Public Procurement Service to empirically estimate the effects of public procurement on firms' productivity (total factor productivity) and survivability. Using a propensity score matching estimation method, we find that participating firms showed higher productivity than non-participating ones in the control group only for the year of participation, that is, 2009. After two years, in 2011, they exhibited significantly lower productivity. In contrast, establishments that participated in public procurement for SMEs in 2009 were more likely to survive than those that did not do so in 2011. These results can be interpreted as the negative consequences of government intervention. The market's efficiency enhancement is hindered if underserving companies survive owing to government intervention but fail to improve efficiency.

• Korean Journal of Adult Nursing
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• v.17 no.2
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• pp.208-218
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• 2005

This study was conducted to develop and evaluate guidelines for cancer patients' symptoms management such as nausea/vomiting, fatigue, constipation, diarrhea, and oral mucositis. Based on the literature review, assessment path to identify each stage of five symptoms were also developed. Guidelines for symptom management of each stage of the symptoms were developed. Guidelines then were evaluated by a panel of experts. Finally, 95 cancer patients were recruited and asked to use the guidelines for their symptom management. Levels of understanding of and satisfaction with assessment path and management guidelines were surveyed. Prevalence rate of five symptoms varied ranging from 20% (diarrhea) to 47% (nausea/vomiting). Regarding the level of understanding of each symptom most of the cancer patients indicated that they were easy and sufficient. Regarding the easiness of use of the symptom management guidelines, most of cancer patients indicated that they were easy to use. Regarding the nursing intervention on each symptom, most of cancer patients indicated that they were easy and helpful. More information was added with feedback from the patients. The result of this study has implications on development of customized patient education materials based on assessment path and symptom management guidelines.

• Korean Journal of Adult Nursing
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• v.25 no.1
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• pp.1-12
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• 2013

Purpose: The purpose of this study was to explore the nurses' perception of the importance of evaluating continuing nursing education programs. Methods: Subjects were 465 nurses enrolled in continuing nursing education programs at five university hospitals in Seoul and Gyeonggi-do. Data were collected from September 20, 2011 to October 13, 2011. The instrument was developed by the author through a literature review. Content validity was established from a panel of six experts. Data were analyzed using SPSS/WIN 18.0 program. Results: The purpose of the program was rated as the most important domain by the subjects. Interestingly, 'program outcome' and 'effectiveness of program' were ranked below the mean (M=$3.64{\pm}0.75$). These two domains were influenced by the district of work and the type of institution. The position of the participants at their institutions made the significant differences on their perception of 'program purpose.' Conclusion: The results of this study might aid us to have better understanding for what nurses perceive the importance of evaluating continuing nursing education programs. This information might be able to be used for improving programs. Further studies are needed to explore the validity of the instruments to evaluate continuing nursing education programs.

• International Commerce and Information Review
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• v.10 no.2
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• pp.305-323
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• 2008

Climate change is one of the broadest and the most complex issues of international environmental cooperation. Concern about climate change has been steadily increasing and has become a worldwide issue. According to IPCC(Intergovernmental Panel for Climate Change)'s recently report, global warming has accelerated vest serious problems. GHG(Green House Gas) emissions trading schemes, including the Kyoto mechanism that spread to solving the problems. Based on the evaluation on GHG emissions trading schemes, we also find some policy implications on the future development of emissions trading the conventional air pollutants in Korea which start to 2007. The regulatory authority needs to make clear how to allocate allowances to new entrants and also to keep the balance between the opportunity costs of reduction between potential shutdown facilities and new entrants. Under the current rule that does not allow shutdown credits, an equivalent level of allowances needs to be allocated to new entrants free of charge. We believe our policy recommendations may be useful not only for Korea but also for a the other countries, since they are facing a similar policy environment as Korea, particularly in the case of climate change.

• Journal of Distribution Science
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• v.15 no.11
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• pp.59-72
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• 2017

Purpose - This paper evaluated the efficiency performance of the three major maritime transport markets and examined the determinants of the performance. The firms' revenue fluctuates with the changes of the economic cycle; hence it is important for them to set up business strategies to improve efficiencies. A lack of efficiency measurements for shipping firms leads to a significant gap in determining their overall performance. Research design, data, and methodology - Each of DEA scores was adopted for the evaluation and panel regression was used to examine the impact of determinants on the performance. The analysis included 50 shipping firms from three maritime transport markets as follows; 15 firms of container liners, 18 firms of bulk carrier and 17 firms of tanker carriers, and its period was from 2010 to 2016. Results - In the CCR model, container liners were the highest, tanker carriers were the second, and bulk carriers were the lowest in operation efficiency and financial efficiency. By region, operation efficiency and financial efficiency was high in the order of America, Asia, and Europe. Conclusions - This study suggests business strategies for maritime transport companies based on the analytical results of determinants of operational and financial efficiency.

• Journal of Biomedical Engineering Research
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• v.29 no.5
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• pp.392-399
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• 2008

Thin-film transistor (TFT) arrays for an x-ray detector require quite different design concept from that of the conventional active-matrix liquid crystal devices (AM-LCDs). In this paper anew design of TFT array which uses only SiNx for passivation layer is described to meet the detector performance and the product availability simultaneously. For the purpose of optimizing the design parameters of the TFT array, a Spice simulation was performed. As a result, some parameters, such as the TFT width, the data line capacitance, and the storage capacitance, were able to be fixed. The other parameters were decided within a permissible range of the TFT process especially the photolithography process and the wet etch process. Then we adapted the TFT array which had been produced by the proposed design to our prototype model (FDXD-1417 and evaluated it clinically by comparing with a commercial model (EPEX, Hologic, Beford, USA). The results say that our prototype model is slightly better than EPEX system in chest PA images. So we can prove the technical usefulness and the commercial values of the proposed TFT design.