• Kyungpook Mathematical Journal
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• v.45 no.1
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• pp.55-65
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• 2005

We find the expression of the curvature tensor field for a manifold with is endowed with an almost contact structure satisfying the condition (1.7). By using this condition we obtain some properties of the Ricci tensor and scalar curvature (d. Theorem 3.2 and Proposition 3.2).

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2005.11a
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• pp.197-203
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• 2005

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.10a
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• pp.243-249
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• 2011

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2005.04a
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• pp.188-190
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• 2005

• Journal of the Korean Mathematical Society
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• v.56 no.2
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• pp.559-578
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• 2019

We list all subfields of cyclotomic function fields over rational function fields with class number three. We also determine all the imaginary abelian extensions with relative class number three, explicitly.

• Tribology and Lubricants
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• v.21 no.4
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• pp.165-170
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• 2005

Engine lubrication system has very complex oil flow networks. Therefore it is difficult to evaluate and optimize the system only depending on experimental results. When we plan upgrading the engine performance the engine lubrication system must be considered in the plan. In this paper, engine lubrication system design using computational fluid dynamic analysis was studied. To do this, unsteady transient flow network analysis on the engine oil circuit system was carried out. Finally we discussed the design process in the modified engine lubrication system.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.1-6
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• 2005

Optimal criterion for the scale-up production of schizophyllan, a fungal polysaccharide secreted by Schizophyllum commune, was investigated. For the production of the polysaccharide in a 150-l bioreactor, the culture conditions optimized in a 15-l bioreactor were applied to a 150-l bioreactor with scale-up process, by changing impeller speed and airflow rate. The optimized impeller speed in the 15-l bioreactor was 50 rpm in a technical medium based on barley. For establishment of the scale-up process, 3 kinds of criteria were used while the gas throughput number was kept constant, as follows; constant volume-related power input, constant tip speed of stirrer, and constant Reynolds number. In the 150-l bioreactor, the highest values for the maximum specific growth rate (1.17/day) and productivity (0.63 g/L${\cdot}$day) were achieved in the culture condition from constant volumerelated power input criterion.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.4
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• pp.204-211
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• 2020

The era of the 4th industrial revolution is a complex environment in which the cyber world and the physical world are integrated and interacted. In order to successfully implement and be sustainable the 4th industrial revolution of hyper-connectivity, hyper-convergence, and hyper-intelligence, not only the technological aspects that implemented digitalization but also the social aspects must be recognized and dealt with as important. There are socio-technical systems and socio-technical systems theory as concepts that describe systems involving complex interactions between the environmental aspects of human, mechanical and tissue systems. This study confirmed how the Socio-technical System was applied in the research literature for the last 10 years through machine learning-based analysis. Eight clusters were derived by performing co-occurrence keywords network analysis, and 13 research topics were derived and analyzed by performing a structural topic model. This study provides consensus and insight on the social and technological perspectives necessary for the sustainability of the 4th industrial revolution.

• Journal of Korean Library and Information Science Society
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• v.34 no.4
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• pp.1-20
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• 2003

Through analyzing papers on digital libraries and the contexts of usage of the term, ‘digital library’, this study investigates that the professional discourses about digital libraries regard them digital technologies. But digital libraries need to be recognized as socio-technical networks which are constructed by social interaction between heterogeneous elements. The study suggested that Social Informatics and a STIN(Socio-Technical Interaction Network) model should be applied to understand and analyze digital libraries as socio-technical networks.

• Ocean and Polar Research
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• v.30 no.4
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• pp.445-451
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• 2008

This paper examines measures of technical efficiency in off-shore fishery based on a frontier production function model of the Cobb-Douglas type. Technical efficiency ranges between 57.13 and 98.62 percent. The results suggest that the highest TE in the industry is the trawl. Also, this analysis shows that Busan's Danish seine fishery has a maximum TE. Angling in Gangwon has a minimum TE. Empirical measures of technical efficiency in this study can be useful in analyzing the potential effects of policies designed to deal with the current fishery industry.