• Journal of Korea Foundry Society
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• v.26 no.1
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• pp.17-26
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• 2006

The substitution of cooling method from water quenching to air cooling after solution heat treatment was aimed for the development of a convenient and economical heat treatment process of duplex stainless steels without deterioration of mechanical and corrosion resistant properties for the industry. In order to achieve this goal, the mechanical properties and corrosion properties of a ASTM A890-4A duplex stainless steel were systematically investigated as functions of casting condition and cooling method after solution heat treatment. A 3-stepped sand mold and a permanent Y-block mold were used to check the effects of solidification structure and cooling rate after solution heat treatment. The microstructural characteristics such as the ferrite/austenite phase ratio and the precipitation behavior of ${\sigma}$ phase and carbides were investigated by combined analysis of OM and SEM-EDX with an aid of TTT diagram. Hardness and tension test were performed to evaluate the mechanical properties. Impact property at $-40^{\circ}C$ and corrosion resistance were also examined to check the possibility of the industrial application of this basic study. Throughout this investigation, air-cooling method was proved to effectively substitute for water-quenching process after the solution heat treatment, when the duplex stainless steel was sand mold cast with a thickness below 15 mm or permanent mold cast with a thickness below 20 mm.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.4
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• pp.74-80
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• 2014

This paper describes the development of the dual-thrust flight motor for enhancing the hit probability of unguided rockets. We designed dual-thrust flight motor by shape modification of the double base propellant with high burning rate, and confirmed the dual-thrust performance by static firing tests. The test results showed the thrust ratio of about 1:7.6 between sustaining phase and boosting phase, and had a quietly normal dual-thrust characteristics. And the results showed that there was not the fire extinction phenomenon of propellant due to the pressure drop.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.14 no.1
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• pp.55-67
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• 1988

• Journal of the Society of Cosmetic Scientists of Korea
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• v.24 no.3
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• pp.129-133
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• 1998

We have studied a relationship between the pattern of complex modulus change versus internal phase volume ratio and the rheological consistency of concentrated W/O emulsions with Magnesium Sulfate in the range 0.0 to 0.5 wt% and with different oil polarities, respectively. The rheological consistency with time of concentrated W/O emulsion was checked using Fudoh Rheometer and the coalescence of deformed water droplets was examined using polarized light microscope(LEICA DMRP). To find the pattern of complex modulus change of the concentrated emulsions versus internal phase volume ratio, the effect of varying water phase volume fraction from 0.78 up to 0.85 on viscoelastic measurements was investigated using rotational rheometer (HAAKE Rheostress RS 50). The rheological consistency was mainly destroyed by the coalescence of the deformed water droplets. The greater the increase of complex modulus was, the less coalescence occurred and the more consistent the concentrated emulsions were. And the pattern of complex modulus increase versus volume ratio has been explained with the resistance to coalescence of the deformed interfacial film of water droplets in concentrated W/O emulsion.

• Journal of the Korean Society for Heat Treatment
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• v.37 no.1
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• pp.9-15
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• 2024

Nd-Fe-B permanent magnets have been utilized on various industrial fields such as electric vehicles, generator, robots with actuator, etc, due to their outstanding magnetic properties even 10 times better than conventional magnets. Recently, there are many researches that report magnetic properties improved by controlling microstructure through adjusting alloying elements or conducting various processing. Especially, post-sintering annealing (PSA) can significantly improve the coercivity by modifying the distribution and morphology of Nd-rich phase which formed at grain boundaries. In this study, Nd-Fe-B sintered magnets were subjected to primary heat treatment followed by secondary heat treatment at 460℃, 500℃, and 540℃ to investigate the changes in microstructure and magnetic properties with the secondary heat treatment temperature. EBSD analysis was conducted to compare anisotropic characteristics. Through the SEM and TEM observation for analyzing the morphology and distribution of Nd-rich phase, we investigated the relationship between microstructure and magnetic properties of sintered Nd-Fe-B magnets.

• The Journal of Society for e-Business Studies
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• v.4 no.2
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• pp.177-196
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• 1999

The current process of weapon system R&D has lots of problems that the phase is complex, the concept of integration and/or connection of related data is laked and don't be digitalized. To solve these problems we should establish the R&D CALS system and to do this, analysis the R&D process is necessary. In this paper, We suggested weapon system R&D CALS concept and model, and analysed R&D process with ARIS Toolset and proposed the new R＆D process and operation scenarios with CALS concept.

• Korean Management Science Review
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• v.12 no.3
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• pp.45-60
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• 1995

This study examines a normative model of project management systems, PPMS, to provide information for directing R&D activity in order to increase R&D productivity. The PPMS (Project Process Management System) is a disciplined and systematic framework to manage R&D projects effectively and efficiently under the assumption of a strategic decision making and long-range planning. The purpose of PPMS is to provide for the management of research organization at different levels an effective management tool; first, for the planning system which deals with rational selection and authorization of R&D projects, second, for the control system which concerns monitoring and controlling the execution of R&D projects, and finally, for the evaluation system which attains evaluation of the performance results of R&D projects and determination of the necessary follow-up. A view for the future development of project management within the context of a project-performing organization is also elaborated to exhibit the progress and phase description of the project management system.

• 한국가스학회:학술대회논문집
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• 1998.09a
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• pp.153-161
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• 1998

• Proceedings of the Korea Technology Innovation Society Conference
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• 2001.05a
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• pp.547-553
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• 2001

A ideal Methodology is a technology that efficiently utilize outputs of research and development (R&D). "Liquid Metal Reactor Design. Technology Development" is under development in Korea Atomic Energy Research Institute (KAERI) as on of the Mid-Term and Long-Term Nuclear R&D by MOST. To upgrade the productivity of the R&D during long period, system type project have been accomplished within plant period through schedule management by phase, outputs auditing, sharing and constructing database.

• New & Renewable Energy
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• v.4 no.1
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• pp.25-30
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• 2008

The R&D budget of energy technology development has increased in the sector of korean energy technology development continuously. In addition to that, KIER, the government invested research institute and unique energy technology R&D research institute, is trying to plan for a big-sized energy R&D program for the well focused R&D and excellent research outcomes. In the phase of R&D process, the planning is one of the most important sectors because it drives the direction of R&D. In this study, we suggest the assessment criteria to select a strategic energy technology R&D programs by the analytic hierarchy process, which is one of multi-criteria decision making method (MCDM)We structure 2 tiers of hierarchy for assessing a big-sized R&D program and also establish 6 criteria in the level 1, which are energy environment, economic spin-off, technical spin-off, marketability, KIER mission, and cost. We allocate the relative weights of criteria by checking the values of consistency ratio as making pairwise comparisons. The result of this research will provide the decision makers as they select a right well focused R&D program.