• Journal of Adhesion and Interface
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• v.3 no.2
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• pp.9-16
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• 2002

In the synthesis of water-based polyurethane using self-emulsification process, after being neutralized, polyurethane pre-polymers containing ionic pendant groups are dispersed by simple convective mixing. Preparation of dispersion is followed by chain extension reaction, which is considered as important step for growth of the molecular weight of polyurethane. In this work, pH variations in the aqueous phase were monitored during the chain extension process in the presence of water-soluble diamines. The optimum degree of chain extension and the average particle size in the polyurethane dispersions were examined with varying ionic pendent group contents, type of chain extenders, and feed rate of chain extenders, The initial pH value in the aqueous phase linearly increased and the optimum chain extension point could be obtained from the intersection of two linear lines having different slopes, All average particle sizes before chain extension reaction were almost same, however, the final average particle size increased as feed rates of chain extenders increased, In addition, as the ionic pendant group contents increased, the particle size decreased since the hydrophilicity and hydrodynamic volume increased. As carbon numbers of the chain extenders increased, the final particle size increased significantly. From the results, it was concluded that the chain extension reaction took place among the particles not only in a particle.

• Proceedings of the Korean Society of Crop Science Conference
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• 2007.11a
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• pp.250.2-250.2
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• 2007

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.298-299
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• 2014

As a governmental plan for real estate revitalization, remodeling vertical extension has been permitted. Thus, the Ministry of Land, Infrastructure and Transport preannounced proclaiming the revised Housing Act and establishing the remodeling basic plan, and it is anticipated that the remodeling market will be revitalized in earnest after the enforcement of remodeling vertical extension(April 25th. 2014). As vertical extension is applicable up to 3 stories, the safety of building for remodeling is becoming important, so most remodeling construction works use various methods for structural reinforcement. In this process, the selection of structural reinforcement method has depended on structural engineer's experience and knowledge and there has been a limitation in selecting the optimum structural reinforcement method which considers remodeling project characteristics. Therefore, this study analyzed the factors to determine the kinds of structural reinforcement method in a remodeling project and suggested a process to select the best structural reinforcement method of remodeling construction.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.254-257
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• 2004

Fiber placement system (FPS) carries out an advanced composites process which orients high strength reinforcing fibers in specific directions. The process includes wet winding, thermoset tape winding, thermoset prepreg placement and thermoplastic prepreg placement. FPS have the advantage of tape laying and filament winding with computer control and software. Using FPS can reduce costs, cycle times, structural weight, and handwork/rework when manufacturing composite parts. The sleeve extension is a part of the helicopter rotator systems. In this study, The sleeve extension composites were manufactured using FPS and tensile properties of this composites were characterized using universal testing machine(UTM).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.273-274
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• 2021

This paper proposes a process to calculate the amount of construction and demolition (C&D) of underground vertical extension methods through considering the characteristics of used construction and demolished materials. The underground vertical extension methods analyzed in this paper were the bottom-up, normal top-down, and top-down methods with multi-post downward (MPD). In order to check the applicability of the proposed process, 24 illustrative examples were generated. The amount of C&D waste of the illustrative examples were calculated and compared. As the results, the top-down method with MPD was the most efficient method to reduce the amount of C&D waste.

• Journal of Agricultural Extension & Community Development
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• v.10 no.1
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• pp.15-29
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• 2003

The study uses agricultural knowledge system theory to explore how traditional knowledge applies to the linkage system of agricultural research and extension in rural Korea. By agricultural knowledge system we emphasize the dynamic networks of actors, processes of negotiation, and the diverse ways in which knowledge is constructed and performed. The knowledge systems reflect the idea that the boundaries between knowledge groups are not closed and that there could be considerable overlap between knowledge system. The results of this study are the following : First, we should know that some extension agents clearly value farmer knowledge and try to facilitate farmer-to-farmer communication. Extension plays a significant role in the knowledge-creation process and shaping communities because knowledge processes are embedded in social processes that involve aspects of power, authority, and legitimization. Third, the constructions of agricultural knowledge systems thus include social interactions, communication, and the diverse processes individuals employ create, use, and evaluate multiple types and sources of information through the linkage between agricultural colleges and Rural Development Administration (RDA), establishing the research institution of research and extension linkage, exchange research agent with extension agent, and bottom-up approach. Second, we should know that the focus of traditional knowledge development is rural community development as a community process. Nowadays the sessions of the Intergovernmental Committee of World Intellectual Property Organization (WIPO) cover two lines of inquiry, which are the use of existing standards of intellectual property for the protection of traditional knowledge and that of new legal standards, eventually in the from of sui generis mechanisms of protection.

• Proceedings of the Korean Society of Crop Science Conference
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• 2005.04a
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• pp.280-281
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• 2005

• Journal of The Korea Institute of Healthcare Architecture
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• v.16 no.2
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• pp.65-75
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• 2010

Space transformation of hospital architecture happens more rapidly than other types such as school and office buildings. This requirement is caused by medical demand, service transformation, technical development and equipment changes. Grand scale extension and rapid change in hospital architecture affects whole planning; therefore, it is important to design in the macro perspective such like Life Cycle. Grand scale extension is difficult process to rebuild growth and transfer of hospital architecture and to adapt to the future change. That's why simple planning gives limits to some departments in a short-term and brings another reform such as more extension or interior renovation in a long-term. This study surveys various space transformation and grand scale extension of EB hospital extended recently, and it is to find planning condition in extension.

• Journal of Agricultural Extension & Community Development
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• v.19 no.3
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• pp.551-579
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• 2012

This case study aims to explore how RDA PLA model affects the agri-SMEs' empowerment. As an agri-business management renovation program from main workshop it was conducted on March to December 2011 with agri-SMEs and extension officials nationwide by RDA. Especially, as a packaged action learning process in the model used participatory action research. This study collected data with participants observation, interviews, situational analysis and systematic review of discourse in qualitative method. For the validity and identifying empirical results, this study used statistic analysis as a mixed method. Further including various pedagogic methods and business coaching skills, this model was conducted from workshop in RDA, in turn, on-farm business coaching as follow-up, CoPs' activities, and local ATCs extension services by each actors. The dynamic process and effects of each process led some change for farmers' innovative knowledge, skills, attitude, practice and aspiration on their farm business. RDA PLA model development based on the previous practices and research, which provided a configurated picture in the holistic action learning process. In statistic research, this study focused on 279 farmers as respondents who had participated in the program. It shows that their income and benefits increased from their renovative practices on farm business. Following the sampling group, it was surveyed by four indicators - products, customer, quality and cost. The level of contribution of education on economic impact 15% is quoted from previous paper. Even in some limitations of public sector, RDA PLA model actively suggests the paradigm shift of agricultural HRD and development of alternative extension-service system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.271-275
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• 2010

Forming tool design is carried out for a manufacturing a outer shell structure of the nozzle extension of regenerative cooling thrust chamber. The method which manufactures outer shell structure of nozzle extension is a metal forming process using thin plate. Because the configuration of outer shell structure is changed after forming process by springback effect, the outer shell structure can't be exactly formed with the same forming tool as configuration of the nozzle extension. Therefore forming tool design considering springback effect is necessary for manufacturing the outer shell structure of the nozzle extension. In this study, new designed forming tool configuration was generated to decrease the errors between nozzle contour and formed structure. The analysis results show that the errors between nozzle contour and formed structure is significantly decreased using the new designed forming tool.