• Journal of the Korean Society of Combustion
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• v.12 no.4
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• pp.47-56
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• 2007

Utilization of sewage sludge for industrial fuel should be considered in appropriate calory with low emission of environmental pollutants and the amount of sewage sludge for continuously long-time operation. For the low grade fuel(<4,000kcal/kg), one of proper processes is that coal and oil are added into sewage sludge to remove impurities and increase calory(>7,000kcal/kg) and the amount of fuel having sewage sludge. Recently, 2-step agglomeration has been attempted by secondarily agglomerate sewage sludge onto the primary nuclei formed by agglomeration of coal and oil. Furthermore, sawdust and waste oil can substitute about 1/3 each for coal and mineral oil consumed in this process, which will lead to securing alternative energy resources from environmental pollutants as well as cost reduction.

• Applied Chemistry for Engineering
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• v.9 no.3
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• pp.364-371
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• 1998

A theoretical model of particle agglomeration was developed to investigate the adhesive force between contiguous coal particles in CWM agglomerate. While heating bituminous coal to about $400^{\circ}C$ or above, the transient occurrence of plastic behavior of coal particles can be observed. The adhesive force in the process of agglomeration of coal particles was found to be proportional to the duration of plasticity of the particles. In the research, how the heating rate and the particle size distribution of CWM fuel influenced the formation of the agglomerate in CWM fuel at the heat-up stage was investigated by the model of particle agglomeration. Simulation program used to this experiment was RKG method and was programmed by Fortran. It was represented that by the model of particle agglomeration, the adhesive force in the process of the particle agglomeration in CWM fuel was inversely proportional to the heating rate but proportional to particle size.

• Korea Trade Review
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• v.45 no.3
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• pp.119-132
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• 2020

In this paper we explore the two analyses to know the urbanization effect on trade. First, the granger causality test to examine the relationship between trade and urbanization. The Granger causality test is a statistical hypothesis test for determining whether one time series is useful for forecasting another. The results indicated that the existence of a bidirectional causality running from trade to urbanization when six lags were applied. When eight lags were applied, we found unidirectional causality running from urbanization to trade. Second, gravity models were used to investigate the urbanization effect on trade. The production cost and specification are affected by the economies of scale, and the economies of scale increased as the greater geographically agglomeration. However, the gravity model to explain the bilateral trade flows ignores the urbanization variables. Therefore we added the urbanization variable represented as the geographically agglomeration into gravity model. The results show that the degree of urbanization of both countries has statistically positive effect on trade (export and import) and the bigger coefficients of trade partner's urbanization. The reason is that the trade share of industrial supplies, intermediate goods and capital goods is much higher than finished consumer goods. The urbanization is more important the improved the efficiency of production than demand market.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6878-6887
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• 2015

This study applies regression analysis and propensity score matching to analyze the agglomeration economies which the characteristics of tenancy affect the performance of the manufacturing industry based on industrial parks. The estimation main data are from Kis-Value, KIPRIS and FEMIS. The results show that the industrial park tenancy tends to work positively on the management performances. But there is no evidence that on-Park firms in the metropolitan areas(Gyeonggi-do) have higher management and innovative performances than the comparable firms. The firms that have lived for a long time in the industrial parks, are good in total sales, however, they have no significant efficiency in net profit, operating profit, and patents. The firms, having several branches of the industrial parks, have lower operating profit than others. Long-term and multiple tenant firms do not learn over time nor do they establish better linkages and networks.

• Clean Technology
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• v.28 no.1
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• pp.46-53
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• 2022

The agglomeration characteristics of coal and silica sand were investigated under various conditions using mixed samples consisting of coal, silica sand, and potassium hydroxide, which is an agglomeration accelerator. The samples were prepared by either physically mixing or using aqueous solutions. The experiments using the physically mixed powder samples were performed with a two hour reaction time. The results showed that the number of aggregates generated increased as the reaction temperature and the total potassium content increased. The experiments using aqueous solutions were performed at 880 ℃, which is the operating temperature of a fluidized bed boiler, and at 980 ℃, which assumes a local hot spot. The amount of agglomeration generated as the reaction time increased and the total potassium content increased was identified. In the experiment performed at 880 ℃, the amount of aggregate generated clearly increased with the reaction time, and in the experiment performed at 980 ℃, assuming a local hot spot, a large amount of aggregate was generated in a relatively short time. The aggregates became harder as the potassium content increased. When the total potassium content was less than 1.37 wt.%, the aggregates were weak at both temperatures and collapsed even with a slight impact. Additionally, the surface characteristics of the silica sand and ash aggregates were observed by SEM-EDS analysis. The analysis revealed a large amount of potassium at the bonding sites. This result indicates that there is a high possibility of aggregation in the form of a eutectic compound when the alkali component is increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1348-1353
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• 2010

At the early stage of a bulk syndiotactic polymerization of styrene, the homogeneous reactant mixture transforms to a slurry state consisting of a precipitated solid syndiotactic PS and a liquid reactant mixture. As the reaction proceeds, the slurry transforms into a wet and then a dried powder if proper methods are used to prevent agglomeration. When a large amount of catalyst and co-catalyst is added to the styrene to achieve a high conversion rate, the reactant mixture becomes a lumpy agglomeration and further control of the reaction is impossible. In this study, we introduce a novel approach to avoid such agglomeration while maintaining a high conversion rate. Instead of adding the catalyst and co-catalyst at once, the total amount of the catalyst and co-catalyst is divided into several parts and added successively. This method is found to be very effective to avoid the formation of agglomerate and to maintain a fairly high conversion rate of slurry into powdery product (up to 70 %). It is also observed that this method produces syndiotactic PS of a higher molecular weigh.

• Journal of the Economic Geographical Society of Korea
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• v.14 no.4
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• pp.628-641
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• 2011

Focusing on the photonics industry as a new one and the photonics industry agglomeration in Gwangju, this study investigated the regional characteristics of the photonics industry's growth. To analyze the location and business network of photonics firms as foundation of industrial growth, in-depth interviews were conducted. It also aimed to review the meanings of regional policy to promote a strategic industry. As a result, it founded the differential growth of the photonics industry in the Capital region(with a market advantage) and Gwangju(with a policy advantage). Gwangju's regional policy had an importance that it formed a regional consensus and increased the momentum and variety to drive regional industrial development.

• Structural Engineering and Mechanics
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• v.73 no.5
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• pp.481-486
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• 2020

This paper deals with the buckling and optimization of a nanocomposite beam. The agglomeration of nanoparticles was assumed by Mori-Tanaka model. The harmony search optimization algorithm is adaptively improved using two adjusted processes based on dynamic parameters. The governing equations were derived by Timoshenko beam model by energy method. The optimum conditions of the nanocomposite beam- based proposed AIHS are compared with several existing harmony search algorithms. Applying DQ and Hs methods, the optimum values of radius and FS were obtained. The effects of thickness, agglomeration, volume percent of CNTs and boundary conditions were assumed. The results show that with increasing the volume percent of CNTs, the optimum radius of the beam decreases while the FS was improved.

• Journal of the Korean Regional Science Association
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• v.13 no.2
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• pp.55-74
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• 1997

This paper investigates the spatial characteristics of networks, which arise as a firm's strategy to enhance its competitiveness to cope with the changing economic environments characterized by technological changes and increasing competitiveness. The theoretical framework in this study proposes that networks emerge as a firm's strategies to promote its competitiveness through the vertical/horizontal disintegration of the production system. Futhermore, regional industries of networks. The study examines the types of cooperation and the spatial boundary of the computer industry networks in Korea. Questionnaire survey was conducted on 1, 128 computer companies which had more than 10 employees, with 126 questionnaires being used for analysis. In addition, newpaper articles were used to supplement the foregoing work on network characteristics. The review of these articles covers the period from Jan. 1994 to June 1996. Major findings of this study are as follows: The spatial range of cooperative networks varies according to the specific characters of cooperation(R & D, production, and seles). Intralocal networks are being developed in Kangnam and Youido area, the computer industry agglomeration clusres of Seoul. There are the regional differnces in the agents and contents of cooperation. In intra-national R & D and production networks, regional differnces in agglomeratins and non-agglomerations are not detercted. Most networks of this type are found between large firms and small firms. In contrast, foregn R & D and production networks, which are operated mostly by large firms, are found in Kangnam, Youido, and CBD. Intra-national and foreign productino networks are also focused in Kangnam, Youido, and CBD. Small firms are playing an active role in making this type of cooperation possible. In the perspective of localization-globalization, Korean computer industry can be analyzed in two respects: industrial and regional. The localization of small firms and the localization-globalization of large firms' networks are being developed in industrial contexts, while the localization-globalization of agglomerations and the localization of non-agglomerations networks are being developed in regional contexts. As networks for the localization-globalization of industry are growing in agglomerations, interfirm networks could be related to trends in the formation or intensification of industrial agglomerations. industrial agglomeration areas function as a facilitator of localization through subcontracts, intraregional network and interregional network. They also facilitate globalization via foregn networks. In non-agglomeratin areas, localization networks, which are connected with agglomeration areas via subcontracting, interregional R & D. or production cooperation.

• Journal of the Economic Geographical Society of Korea
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• v.15 no.1
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• pp.42-62
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• 2012

This paper suggests a genuine method to estimate the agglomeration effects of Industrial Cluster focusing on the FOODPOLIS (KOREA NATIONAL FOOD CLUSTER). In this study, we will focus on two issues related to the clustering effect. First, Clusters affect productivity, and a cluster allows companies to operate more productively in inputs; accessing technology, human resource, information, services, and needed institutions. Second, we assume that the effects of Industrial Cluster can be estimated from measurement on differency of an added value between large-scale enterprises and smaller ones. To demonstrate effectiveness of this approach, the estimated effect was compared with that from the related study (A Mini-Cluster). Industry Clusters have been considered as critical factors for regional competitiveness and economic revitalization. For this, the government and local government should find a way and strategy to provide useful contents that can attract the participation of firms and to secure strategic positioning and competition strategies.