• Journal of Gifted/Talented Education
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• v.25 no.3
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• pp.381-399
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• 2015

The purpose of this study was to investigate teachers' perception of Advanced Placement Program. Participations of this study were 111 teachers from science high schools and gifted science high schools. The results showed as follows. First, teachers perceived positively regarding AP program and were willing to teach AP program. However, teachers perceived that schools were not ready to start AP program. Also, They perceived that teaching materials development, more teachers to teach AP programs, and teacher training programs were needed to set up AP Programs in science high schools. For the professional development, 60-hours teacher training program and incentive system for the AP teachers were needed. Implications of the study were discussed in depth based on the results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.61-65
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• 2005

In HTPB/AP propellants, zirconium(Zr) addition to formulation was shown to be less specific impulse than aluminum(Al) by the theoretical calculation because of the lower flame temperature and higher molecular weight of Zr oxide. It was found that the burning rate was faster with the finer size of Zr and the more content of $2{\mu}m$ Zr the faster burning rate is in HTPB/AP/Zr propellants caused by the more conduction energy transfer from Zr flame to the burning surface. Also the burning rate of HTPB/AP/Zr propellant could be reduced by addition of 150nm Al, depending on AP size distribution in formulation with Butacene and $1{\mu}m$ AP.

• Communications of Mathematical Education
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• v.20 no.1 s.25
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• pp.103-115
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• 2006

We integrated and utilized the currently existing international AP(Advanced Placement) program in mathematics. In 2005, the KMEHRD(Korean Ministry of Education and Human Resources Development) began the mathematics AP program; we attempt to maximize its effectiveness through continuous development. In boosting educational excellence, our AP program will affect the intellectual desire and enhance the performance of mathematically gifted leaners. This program assists high school students to achieve their fullest potential.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.2
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• pp.9-16
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• 2005

Zirconium(Zr) addition to formulation of HTPB/AP propellants, was shown to be less specific impulse than aluminum(Al) by the theoretical calculation because of the lower flame temperature and higher molecular weight of Zr oxide. It was found that the burning rate was faster with the finer size of Zr and the more content of $2{\mu}m$ Zr the faster burning rate is in HTPB/AP/Zr propellants caused by the more conduction energy transfer from Zr flame to the burning surface. Also the burning rate of HTPB/AP/Zr propellant could be reduced by addition of 150nm Al, depending on AP size distribution in formulation with Butacene and $1{\mu}m$ AP.

• Journal of Gifted/Talented Education
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• v.26 no.2
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• pp.405-421
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• 2016

The purpose of this study was to investigate students' perception of Advanced Placement Program. Participations of this study were 1144 students from 14 science high schools. The results showed as follows. First, students perceived positively regarding AP program and were willing to take AP courses because of interesting and challenging in academic area which is provided by AP courses. Secondly, many students would like to take AP courses in Differential and Integral Calculus 1, General Physics I, General Chemistry I and General Biology. Also, they would like to take AP courses in first term as a mandatory subjects. Third, responses perceived that AP courses were challenging, difficult, and of high quality. Finally, students perceived the benefit of AP courses in earing college credit. However, 35% of responses wished to receive an exemption for all AP courses. Also, they wished to have dual-major or participate in students exchange program as a benefit of AP program. Implications of the study were discussed in depth based on the results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.576-584
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• 2016

In this study, AP added propellant has been proposed as a method of enhancing the low specific impulse performance found for staged hybrid rocket engine. Experimental tests were carried out to analyze and evaluate the effect of AP added propellant on specific impulse performance as well as fuel-rich combustion characteristics in a staged hybrid rocket engine. Upper limit of AP content in propellant was set to be 15 wt% to maintain the hybrid rocket engine advantages. As a result, 15 wt% AP added propellant showed 3% higher specific impulse performance compared to 0 wt% AP added propellant. Moreover, AP addition proved to offer less injected oxidizer mass flow, less O/F variation, and less combustion pressure while producing fuel-rich gas of the same combustion temperature. Future studies will carry out more combustion tests with metal additives to further enhance specific impulse.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.207-210
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• 2009

The AP/HTPB composite propellant is a common choice for solid rocket propulsion. The externally heated rocket via fires, for instance, can cause the energetic substance to ignite, and this may lead to a thermal runaway event marked by a severe explosion. In order to develop preventive measures to reduce the possibility of such accidents in propulsion systems, we investigate the ignition and initiation properties of AP/HTPB propellant.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.279-282
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• 2008

The AP/HTPB composite propellant is a common choice for solid rocket propulsion. The externally heated rocket via fires, for instance, can cause the energetic substance to ignite, and this may lead to a thermal runaway event marked by a severe explosion. In order to develop preventive measures to reduce the possibility of such accidents in propulsion systems, we investigate the ignition and initiation properties of AP/HTPB propellant.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.390-393
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• 2010

The thermal decomposition rate of ammonium perchlorate with 3% of yellow iron oxide, FeOOH was found to be much faster than with red iron oxide, $Fe_2O_3$. By applying yellow and red iron oxide as a burning rate modifier to HTPB/AP propellant, burning rate of the HTPB/AP propellant with yellow iron oxide was shown to be 10 ~ 25% faster than with red iron oxide. There was no special difference in viscosity and hardness buildup of yellow and red oxide added HTPB/AP formulations.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.1
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• pp.14-19
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• 2016

The viscosity and mechanical property of HTPB/AP composite solid propellant are profoundly affected by particle size of AP. In HTPB/AP propellant formulated by two mode of AP size such as $190{\mu}m$ and $7{\mu}m$, the propellant was found to be much less viscose at end of mix when coarse/fine AP ratio is ranged from 70/30 to 60/40 due to high solid packing fraction. It was shown that the toughness of tensile strength test for HTPB/AP propellant increased with the increase in coarse AP. Considering both lower viscosity and better tensile strength, the optimum ratio of AP coarse/fine was estimated to be 70/30.