• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.549-555
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• 2005

To evaluate the posterior and anterior restoration of polymeric dental restorative composite (PDRC), PDRC was prepared using a silica filler treated by heat at various temperatures. Compressive strength (CS) and diametral tensile strength (DTS) values were investigated to study the effect of a heat-treated silica on the mechanical properties of PDRC using the recommended dental specifications. Both the particle size and specific volume of silica were decreased upon increasing the heat treatment temperature. CS and DTS values of PDRC containing a heat-treated silica showed 1.2 and 1.3 times, respectively, higher than that of the PDRC containing a neat silica. Also, it was found that the lower heat treatment temperature, the better mechanical properties of PDRC were observed because there was less agglomeration between silica particles. Specially, PDRC using a silica treated at $600^{\circ}C$ showed superior mechanical strength.

• Journal of the Economic Geographical Society of Korea
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• v.8 no.2
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• pp.195-215
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• 2005

This study was carried into execution to analyze Spatial Characteristics of Seoul Business Services Cluster in circumstance of local economic development led by knowledge-intensive business services. The analysis was performed for industrial agglomeration and companies' linkage and network. As the result, there are three business services cluster, including the largest one in Gang-Nam Gu, Seoul, and for last 10 years, there has been increasing development of business services cluster. In the meanwhile, their linkage and network have not been performed briskly. Therefore, from now on, a plan that can help companies' linkage and network performed inside of cluster to have active and international structure has to be considered in cluster policy.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.28 no.3
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• pp.273-282
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• 2018

Objectives: Dustiness of nanomaterials is considered as exposure index of essential material. Research on dustiness of nanomaterial is needed to control exposure in workplaces. Method: Dustiness measurement using vortex shaker were installed in the laboratory. Nanomaterials, 1 g, was put in the glass test tube and shaked using vortex shaker. Aerosol dispersed was measured using scanning mobility particle sizer(SMPS) and optical particle counter(OPC). Mass concentration using PVC filter and cassette was measured and TEM grid sampling was conducted. Total particle concentration and size distribution were calculated. Image and chemical composition of particles in the air were observed using transmission electron microscopy and energy dispersive X-ray spectrometer. Eleven different test nanomaterials were used in the study. Results: Rank of mass concentration and particle number concentration were coincided in most cases. Rank of nanomateirals with low concentration were not coincided. Two types of fumed silica had the highest mass concentration and particle number concentration. Indium tin oxide, a mixture of indium oxide and tin oxide, had high mass concentration and particle number concentration. Indium oxide had very low mass concentration and particle number concentration. Agglomeration of nanoparticles in the air were observed in TEM analysis and size distribution. In this study, mass concentration and particle number concentration were coincided and two index can be used together. The range of dustiness in particle number concentration were too wide to measure in one method. Conclusion: Particle number concentration ranged from low concentration to high concentration depend on type of nanomaterial, and varied by preparation and amount of nanomaterial used. Further study is needed to measure dustiness of all nanomaterial as one reference method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.165-174
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• 2016

This paper examined opportunities and limitations of building an innovation cluster based on large scale research facilities (LSRF). For this purpose, success factors of innovation clusters were drawn from the literature, and categorized into knowledge & technology, transaction cost & agglomeration economies, hardware & software infrastructure, and government policy & strategy. Utilizing the categorization as an analytic framework, case studies of CERN and SPring-8 were performed. The results showed that there were various innovation processes for both cases, creating opportunities for developing innovation clusters in terms of knowledge and technology. On the other hand, in the case of SPring-8, there were disadvantages in the transaction cost and agglomeration economies, being located in a remote area due to the nature of the facility. Software & hardware infrastructure of SPring-8 limited its potential for innovation clusters. Regarding government policy and strategy, CERN, as a multinational institution, did not consider an innovation cluster in a specific region despite some advantages. An innovation cluster around SPring-8 was promoted by government policy despite some disadvantages. In other words, the advantages and disadvantages were enhanced or complemented by software & hardware infrastructure and government policy & strategy. Based on the results, this paper provides the implications for the Korean International Science-Business Belt.

• Journal of the Economic Geographical Society of Korea
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• v.7 no.2
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• pp.261-281
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• 2004

The location of auto industry in Jeon-buk is due to the strategies for secure a low-priced industrial site of the auto assembly companies, which attained to quantitative growth stage in the early part 1990's, and the regional balanced development policy by the location of leader enterprise of the government. As a consequence of the reversal development pattern that is located the auto parts firm after locating the auto assembly companies, the Jeon-buk auto industry has many structural vulnerability. First, because of the lack development of auto parts industries, the auto assembly companies located in Jeon-buk are dependent many auto parts at a external region. Second, most of auto parts firm belongs to the singular assembly company exclusively. And the majority of auto parts industries are the low value-added products that are necessary a simple labor power. Third, the agglomeration undeveloped of associated industries with automobile caused a low competitiveness of invitation a manufacturing company as against other provinces. For a regional economic development by the auto industry, it is necessary a flexible regional structure of production through an agglomeration of associated industries. The geographical proximity between an assembly company and a parts firms is an important locational factor with the induction of Just-in-Time production system and a modularization in the auto industry. And a modularization applies to more new factory than the existing factories. So that, Jeon-buk self-government has to create an amicable industrial environment, try to attract an auto parts enterprises and plan an agglomerated industrial complex that is able to supply a parts modulated to assembly company.

• Applied Chemistry for Engineering
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• v.28 no.2
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• pp.214-220
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• 2017

The spherical Al/RDX/AP composites with an average size of $550{\mu}m$ were successfully prepared by drowning-out/agglomeration (D/A) process. The surface morphology and dispersion of Al particles of those composites were investigated using SEM and EDS (energy dispersive spectrometry). As a result of thermal analysis, the onset temperature of thermal decomposition of the Al/RDX/AP composites by the D/A process was found to decrease about $50^{\circ}C$ and their thermal stability was shown to be relatively enhanced due to the increase of activation energy compared to those of using the physical mixing method. In the first decomposition region of AP, Prout-Tompkins model was shown to describe well the thermal decomposition of both composites by the physical mixing and D/A process. On the other hand, in the second decomposition region of AP, the decomposition mechanisms of composites by the physical mixing and D/A process were explained by the zero-order and contracting volume model, respectively.

• Journal of the Economic Geographical Society of Korea
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• v.19 no.4
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• pp.799-811
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• 2016

After the participatory government began, various cluster policies in explicit and tacit forms had been promoted. However, an opinion of coming up with new policy alternative different from the existing one is recently brought up for strengthening the competitiveness of industrial agglomerations. This research attempts to discuss the ways in which both a smart specialization strategy and a triple-helix innovation system approach, as an alternative approach to regional industrial policy, are theoretically associated with the existing cluster policy. Through this discussion, it highlights that post-cluster policy should be not just based on regional specificity, but also facilitated by establishing the consensus space of innovation on the bassis of voluntary cooperation among industry, academy and government. It also stresses that it is necessary to focus on nurturing a new industry by systematic and intensive investment and the diversification of industrial cluster for reinforcing competitiveness of local universities and revitalizing practical cooperation between industry and university.

• Journal of the Korean association of regional geographers
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• v.18 no.4
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• pp.400-413
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• 2012

The purpose of this study was to look into the formation process and characteristics of local high-tech industrial complex with an example of the Ochang Scientific Industrial Complex and analyzed the characteristics by business type and size, transfer process of the companies in the Complex. For this purpose, statistical data of the companies were analyzed and a survey of them was conducted, and the following results were obtained. First, the Ochang Scientific Industrial Complex was created for agglomeration of IT industries in early days but now there are IT industries and BT industries mixed due to internal and external economic condition. Second, there are more small and medium companies than large companies in the Ochang Scientific Industrial Complex. These companies are in the stage of developing new products and marketing, and many of them were parts and materials developers of core technology or high innovation with venture identification. Third, high rates of the companies in the Ochang Scientific Industrial Complex came from the capital area and the Chungcheong area and the companies which moved in the Complex with their head quarters accounted for more than 70 percent. Fourth, the companies were classified into 5 types according to the type of product and the level of technical innovation.

• Journal of the Economic Geographical Society of Korea
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• v.25 no.4
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• pp.547-567
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• 2022

In this study, I focus on makerspaces, which have rapidly spread since the late 2000s in the world's major cities. Makerspaces, born amid great social change, reflect the core characteristics of industrial space. I analyze the makerspace based on the theoretical perspectives of urbanism in the macroscopic aspect and placeness in the microscopic aspect. The urbanism of makerspaces is manifested through entry into the inner cities and their connections with urban capabilities. This means that convergence with innovation factors is becoming more important than optimization of factor costs and agglomeration economies in the locational determinants of industrial space. The placeness of makerspaces is being re-formed through an emphasis on taste, the expansion of autonomy, and the strengthening of connections. This reveals how the value creation process within the industrial space is changing, from forming-placelessness through standardization, uniformity, and compartmentalization to forming-placeness through restoration of individual humanity and interaction. The results of the urbanism and placenesss analysis carry implications for the present moment, when it is necessary to diversify the spatial planning of industrial spaces.

• Journal of Distribution Science
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• v.13 no.4
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• pp.29-33
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• 2015

Purpose - This paper aims to explain the interactive relationship between small and medium-sized enterprises' clusters and regional economic growth, with Jiangsu Province as an illustrative example. It focuses on studying the promotional effects, if any, of small and medium-sized enterprises' cluster-development on regional economic growth, and vice-versa. Research design, data, and methodology - Data were collected from the Jiangsu Statistical Yearbook and the China Industrial Economic Statistical Yearbook, by selecting 26 industries as the research subjects. The sample interval selection is 1981-2012. The data were analyzed with the dynamic panel system using stata 12.0. Results - 1) The small and medium-sized enterprises' cluster degree and Jiangsu's economic growth have a long-term stable equilibrium relationship. 2) In the short term, they have a dynamic adjustment 3) The enterprises' cluster degree leads to regional economic growth in Jiangsu, but not vice-versa. Conclusions - Small and medium-sized enterprises' clusters have an important promotional effect on Jiangsu's economic growth, especially industries with high degree of agglomeration. Therefore, the formation of these clusters can significantly improve economic growth.