• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.113-122
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• 2002

A numerical analysis on the uniformity of propellant injection velocity of KSR-III has been carried out to give design improvements. Injector holes were approximated as porous media with the same pressure drop . The injection velocity is higher at the opposite side of the inlet for both LOX and fuel due to the static pressure rise in the stagnation region. Flow passages at the vertical circular plate in the LOX dome increase the uniformity of LOX injection. Little change was observed in the injection uniformity and pressure drop for the slanted LOX passage. Also provided were the O/ F ratio distributions from the oxidizer/ fuel injection velocity analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.95-98
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• 2010

A multi-injector rocket engine using high concentrated hydrogen peroxide and kerosene as the oxidizer and fuel was designed and fabricated. Six coaxial swirl injectors were mounted on the mixing head and flow analysis in the manifold was performed to minimize stagnation and recirculation zones. Finally, uniformity of mass flow rate and spray pattern was evaluated by cold flow tests and the mixing head design process was successfully verified the results.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.2
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• pp.220-229
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• 2016

A numerical study on lifted flame structure in impinging jet geometry with syngas composition ratio was investigated. The numerical calculations including chemical kinetic analysis were conducted using SPIN application of the CHEMKIN Package with Davis-Mechanism. The flame temperature and velocity profiles were calculated at the steady state for one-dimensional stagnation flow geometry. Syngas mixture compositions were adjusted such as $H_2:CO=10:90(10P)$, 20 : 80 (20P), 30 : 70 (30P), 40 : 60 (40P), 50 : 50 (50P). As composition ratios are changed from 10P to 50P, the axial velocity and flame temperature increase because the contents of hydrogen that have faster burning velocity increase. This phenomenon is due to increase in good reactive radicals such as H, OH radical. As a result of active reactivity, the burning velocity is more faster and this is confirmed by numerical methods. Consequently, combustion reaction zone was moved to burner nozzle.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.674-677
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• 2007

Recently, construction industry has came to a crisis due to stagnation and saturation of the domestic construction market. So, many construction companies in Korea has turned their eyes upon extending the business market abroad, in order to overcome such obstacles. Even though the overseas expansion has been exploited since the mid-1960s, there still lies many problems : excessive focusing on the plant construction, a shortsighted policy of government. In this paper. we analyze the characteristics of advancement into overseas construction market and deduce the problems. then propose the new strategies based on SWOT Analysis.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.1
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• pp.149-153
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• 2011

In this study, we structuralized the diagnostic indices used for pattern identification (PI) of stroke, and suggested an AHP method to obtain the weights of PI indices. AHP of the subjects under consistency ratio 0.1 showed that the critical indices for stroke PI consists of 9 for Qi-deficiency, 13 for Phlegm/dampness, 7 for blood stagnation, 12 for Yin-deficiency and 16 for Fire/heat. Furthermore, AHP analysis rendered the weights of indices of each PI that will be useful for oriental medical experts to perform objective PI.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1658-1666
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• 2009

This paper proposes an approach of Mult_HPSO based on the PC cluster system to reduce or remove the stagnation on an early convergence effect of PSO, reduce an execution time and improve a search ability on an optimal solution. Hybrid PSO(HPSO) is combines the PSO(Particle Swarm Optimization) with the mutation of conventional GA(Genetic Algorithm). The conventional PSO has operated a search process in a single swarm. However, Multi_PSO operates a search process through multiple swarms, which increments diversity of expected solutions and reduces the execution time. Multiple Swarms are composed of unsynchronized PC clusters. We apply to SCED(security constrained economic dispatch) problem, a nonlinear optimization problem, which considers line flow constraints and N-1 line contingency constraints. To consider N-1 line contingency in power system, we have chosen critical line contingency through a process of Screening and Selection based on PI(performace Index). We have applied to IEEE 118 bus system for verifying a usefulness of the proposed approaches.

• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.6
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• pp.27-36
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• 2002

The objective of this study is to improve the quality of the atmospheric environment by incorporating the factors of meteorology and urban climate into the field of urban and environmental planning. To this end, we have conducted a study on CLIMATOP and the mapping of urban climate, which are basic data used to analyze changes in climatic factors and the stagnation and accumulation of air pollutants. In particular, we focused on understanding the formation and movement of cold fresh air and its influx into urban areas by measuring and analyzing climatic factors. As a study result, classification criteria far CLIMATOP and a urban climatic map were made. In addition, we analyzed a digital elevation model, climatic data, and isothermal curves. As a result, we identified the corridor through which cold fresh air moves. We also observed that the temperature of the fluxed cold fresh air increased as land use changed. When the results of this study are applied to urban re-development and re-building projects, which require preliminary environmental assessment and environmental impact assessment, the practice proposed by this study is expected to contribute to the natural purification of air pollution activating the movement of cold fresh air and its influx into urban areas.

• Journal of the Korean Institute of Rural Architecture
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• v.10 no.2
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• pp.27-36
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• 2008

This study is progressing or suggests effective space planning for rural village area conventional markets that is planning business market modernization process. Rural village area conventional markets of small scale are inputting a lot of efforts and financial resources for activation. Also, I wish to quote activation plan for rural village area conventional markets that face in stagnation. Studied spatial form and conventional market activation factors by space use special quality of rural village area conventional markets for architectural planning plan presentation. Investigated spatial change for several years that appear in Geum-wang conventional market for this. As a result, could deduce plans of space improvement plan for conventional market space positively. Also, through this study, suggest activation plan of conventional market that display similar space type including Geum-wang conventional market. Therefore, environment improvement of conventional market's type and special quality based on space activation elements and need space environment improvement plan the architecture plan in early planning phase of business.

• Korean System Dynamics Review
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• v.10 no.4
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• pp.5-25
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• 2009

Since the end of the 1950-1953 Korean War, many scholars and policymakers have expressed concern about the possibility of another conflict on the peninsula. In certain respects, the post-1953 North-South Korea relationship resembles the Cold War that existed between the United States and the Soviet Union, 1945-1990. Although a "hot" never occurred, peace was never guaranteed. By looking at international theories (i.e., realism and liberal theory) and by utilizing casual-loop diagram analysis, the main purpose of this research is to explore on the likelihood of peace and war on the Korean peninsula. First, several factors (e.g., economic stagnation of North Korea, unstable political systems, and so on) emphasized by realism perspectives are significantly related to the likelihood of conflict between North and South Korea. Conversely, several determinants (e.g., economic assistance to North Korea, inter-dialogue between two Koreas, cultural and social exchange, and so on) emphasized by liberal approaches are significantly related to likelihood of peace on the Korean peninsula. Given the two different interpretations about the likelihood of conflict or peace, it can be argued that a second military action might occur on the Korean peninsula if realism theories are true. However, if practical factors exist on the Korean peninsula, the two Korean can optimistically expect a peaceful reunification in the future, without interference from other countries.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.104-106
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• 1993

Some cardio-vascular assist systems need more inexpensive artificial heart valves for short-term use. To meet with this need, we have developed a new polymer valve that is very simple to manufacture and of which its dimensions are easy to change, depending on its application. We have tested the hydrodynamic performance of the new polymer valve using a mock circulatory testing system and studied the flow through the valve using high-speed camera combined with image processing techniques. The results show that this valve is superior in its performances to the other valves (Bjork-Shiley mechanical valve and trileaflet polymer valve) and have no stagnation points. We also have tested the hemolytic potential of the valve. The valve is less hemolytic than the Bjork-shiley mechanical valve finally, we have applied this valve to a left ventricular assist device that we are developing.