• Resources Recycling
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• v.7 no.3
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• pp.42-51
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• 1998

Hydrogen in atmosphere can easily dissolve in melt of light metal alloys. Increasing demand for recycling of light metal a alloys has, therefore, focused attention on the removal of hydrogen gas, and alloy addition in melt has become an imporLant r refining process. For this purpose behaviors of mixing and hydrogen degassing in impeller agitated refming vessel with/without barnes were investigated. Flow patterns, mixing time behavior and kinetics of degassing in various agitating conditions were analysed in watet model experiments. And, numerical analysis on turbulent flow pattern in impeller agitated vessels was performed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.392-396
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• 1995

Chitosan was prepared from red snow crab (Chinonecetes japonicus) under various conditions of deacetylation (NaOH concentration, heating temperature, heating time and intermittent and repetition treatment). By measuring the degree of deacetylation and the molecular weight (Mw), effect of preparation condition was studied. As the concentration of NaOH increased in deacetylation process, for chitosan treated over $40\%$ NaOH, the rate of increase of the deacetylation of chitosan decreased, but the difference of Mw decrease was nearly constant. When treatment temperature increased from $130^{\circ}C$ to $150^{\circ}C$, the deacetylation degree increased only $3^{\circ}C\;from\;84\%\;to\;87\%,$ but Mw decreased from 267,000 to 85,800. The difference of Mw decrease of chitosan treated $130-150^{\circ}C$ was larger than that with $90-130^{\circ}C$. The deacetylation degree and Mw of the chitosan prepared by continuous treatment for 3 hrs was$84\%$ and 267,000. On the other hand those of chitosan with intermittent and repetition treatment for 3hrs was $93\%$ and 28,000. In order to increase the degree of deacetylation and inhibit depolymerizing, the intermittent and repetition treatment was found to be more effective than the continuous treatment.

• Journal of Korea Foundry Society
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• v.43 no.6
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• pp.271-278
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• 2023

In the present study, A356 melt degassing experiments were conducted under various impeller rotation speed and inert gas flow rate conditions to determine changes in the melt temperature, composition and density during a degassing treatment. The melt temperature was found to decrease gradually as the degassing time increased, but a clear correlation between the impeller rotation speed or inert gas flow rate and the melt heat loss could not be confirmed. Regardless of the impeller rotation speed or inert gas flow rate, the Mg and Ti contents in the A356 melt scarcely changed, even after degassing for more than 10 minutes, while Sr contents decreased at the maximum degassing rate of 70 ppm. From a quantitative analysis of the degassing rate under each experimental condition based on the hydrogen concentration in the melt derived from the melt density and the degassing model equation, the inert gas flow rate was found to affect the degassing rate rather than the impeller rotation speed under the degassing operation condition employed in the present study.

• Journal of Technology Innovation
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• v.17 no.1
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• pp.49-67
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• 2009

As technological capabilities have enhanced, the patterns of innovation activities of latecomer firms changed to post catch-up mode. The purpose of this research is to analyze the post catch-up innovation patterns of technology-intensive small and medium firms of Korea. The innovation patterns can be divided into three types: the technology deepening innovation type, the new technology based innovation type and the architectural innovation type. The characteristics of the technology deepening innovation type are cumulative technological learning and the integration of new generic technology and existing technologies. The characteristics of new technology based type are the acquisition and revelations of new basic knowledges from former incubating organizations such as large firms and universities. The characteristics of the architectural innovation type are the learning of system architecture knowledge from former organization and interactive learning with user firms. These post catch up innovations also have some general characteristics. They effectively exploited the windows of opportunities which are opened in the middle of technological paradigm change.

• Journal of Technology Innovation
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• v.20 no.1
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• pp.75-114
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• 2012

Transition from imitation based catch-up to new value creation based post catch-up innovation system is becoming the main issue for Korea. The notion of post catch-up research highlights the understanding of new patterns of innovation and the interrelationship among innovating agents within systems of innovation. More specifically, it is a context specific framework which accommodates discontinuum of technological innovation from the past and a creation of new organizational arrangement and institutions. Moreover, post catch-up approach follows the tradition of development, institutional and evolutionary theories context. This paper, therefore, explores whose focus is on the possibility of new theoretical development and new research agenda.

• Journal of Digital Convergence
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• v.14 no.9
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• pp.19-29
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• 2016

This study analyzes life experiences and prospects of poverty/welfare exit of the poor with work ability utilizing Mixed methodology. Based on Sequential Exploratory Design, it qualitatively analyzes 3 waves of qualitative panel data linked to Korea Welfare Panel Study(KWPS) and presents life changes of 14 poor in the context of their prospects of welfare/poverty exit. Then it proposes hypotheses on the role of education, household economy expectation, self-esteem in the prospects of poverty/welfare exit following the sequential exploratory design to quantitatively test qualitative findings utilizing KWPS(7th). The outcomes of the Structural Equation Model(SEM) suggest that household economy expectation plays mediating role between education and the prospects of welfare/poverty exit. This implies that anti-poverty policy needs to consider a psychological approach to enhance household economy expectations of the poor as well as other material support.

• Journal of Navigation and Port Research
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• v.46 no.6
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• pp.501-508
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• 2022

The flow of global digitalization is leading to the emergence of a decentralized system environment based on blockchain or distributed ledger technology in the fields of economy, identity authentication, and logistics. Accordingly, a requirement that public services be searchable from several decentralized maritime service registries (MSRs) has been derived in terms of the discoverability of e-navigation services. This study describes a decentralized MSR environment composed of the MSR ledger and multiple local MSRs, and it has implemented a service search system that can search global e-navigation services in the environment through a web browser. This system is a decentralized application that dynamically generates service attributes, geometry information, and free text queries, and that provides users with relevant MSR and service access information from search results that are registered in the MSR ledger. In this study, we tested the established decentralized MSR environment and the system that performs service search within that environment, and we discussed its advantages and limitations.

• 한국사회복지학회:학술대회논문집
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• 2006.04a
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• pp.354-358
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• 2006

• Nuclear industry
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• v.37 no.6
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• pp.88-90
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• 2017

• Journal of the Korean association of regional geographers
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• v.22 no.3
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• pp.576-598
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• 2016

This paper is to reconsider some characteristics of philosophical discussion on alienation, especially focusing on Lefebvre's concept of alienation, and then to conceptualize a number of features of alienation in both industrial and postindustrial capitalist cities. The construction and development of modern city in industrial capitalism has brought about alienation from nature and from land(i.e. means of production), and in these contexts, has generated alienated labour of urban labourers, which has been deepened through development of modern technologies and divisions of labour. The transformation from industrial to postindustrial society can be seen not as alleviating but as further intensifying and expanding process of alienation. Urban alienation in postindustrial society has been spatially and temporally extended through processes of glocalization and of financialization with the development of credit system. It also has been widened to fields of consumption and leisure and to spheres of non-material production, and has get more deeply involved in capital circulation through built environment and landscape(or spectacles) of cities. Finally this paper is to re-examine briefly theoretical discussions on dealienation in order to conceptualize the just city for dealienation of labour and of urban space, in particular considering the concept of 'the right to the city' as practical strategy of urban dealienation, and to suggest further three kinds of justice for the just city, that is, justice for distribution, for production and for recognition.