• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.87-92
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• 2006

The rocket grade hydrogen peroxide has been widely used as a monopropellant in propulsion systems. In the present paper, we described an experimental study of a catalytic reactor that employs two stage catalyst beds to enhance the low temperature performance of the reactor inlet. $K_2MnO_4$ was chosen as the catalyst for the initial stage of the reactor bed for its superior behavior in the low temperature regime. Alumina sol-gel method was successfully applied for coating $K_2MnO_4$ on a reactor bed of cordierite monolith. LSC was used for the catalyst of the second stage of the reactor. The reactor with combined catalyst beds was built and tested to exhibit superior performance in low temperature regime and high decomposition efficiency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.55-62
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• 2010

In addition to the previous study for development of a 1,200 N-class bipropellant rocket engine with concentrated hydrogen peroxide, the effect of characteristic length and thrust measurement were experimentally evaluated. Tests with characteristic lengths of 0.95, 1.07, and 1.20 m were performed and $C^*$ and Isp efficiencies were increased as increasing characteristic length. The maximum $C^*$ and Isp efficiencies were 98.4% and 93.1% respectively. Based on the evaluation of the designed engine, the optimized characteristic length was proposed in using the engine adapted decomposed hydrogen peroxide and the engine performance at vacuum-level was evaluated using thrust and Isp efficiency at the designed equivalence ratio. As a result, 218.4 s at sea-level, 253.3 s at vacuum-level, and vacuum thrust of 1035.3 N can be estimated.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.3
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• pp.1-8
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• 2011

In addition to the previous study for development of a 1,200 N-class bipropellant rocket engine with concentrated hydrogen peroxide, the effect of characteristic length and thrust measurement were experimentally evaluated. Tests with characteristic lengths of 0.95, 1.07, and 1.20 m were performed and $C^*$ and Isp efficiencies were increased as increasing characteristic length. The maximum $C^*$ and Isp efficiencies were 98.4% and 93.1% respectively. Based on the evaluation of the designed engine, the optimized characteristic length was proposed in using the engine adapted decomposed hydrogen peroxide and the engine performance at vacuum-level was evaluated using thrust and Isp efficiency at the designed equivalence ratio. As a result, 218.4 s at sea-level, 253.3 s at vacuum-level, and vacuum thrust of 1035.3 N can be estimated.

• 한국체육학회지인문사회과학편
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• v.58 no.3
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• pp.241-260
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• 2019

The purpose of this study is to explore effective and practical career plans reflecting demand of the field, in regard to education for university students who major in physical education, as the importance and necessity of career education at a university level are increasing. Systematic literature review (PRISMA) methodology was used for this study. From 38 pieces of literature that were finally selected for this study, research results were put together from three perspectives as follows: 1. 'Factors Related to Students' Decision-Making for Career' which should be considered in career education for physical education majors; 2. Problems of Career Education in the Physical Education Curriculum, and; 3. Improvement Plans. First, it was found that students' decision-making for career is affected by individuals' personal internal factors (i.e., satisfaction with major, self-efficacy, and career barrier) and external factors (i.e., counselling history on career paths, career conditions, and the status of related jobs). Second, the state of career education for physical education majors was found to be insufficient in terms of a lack of career education in the curriculum, a lack of support from major professors, and a lack of support for field experience. Third, improvement plans were suggested from the following perspectives: development of systematic career education curriculum (i.e., fostering leadership, reorganization of curriculum focused on career specialty, and operation of systematic curriculum); provision of an adequate environment for career education (i.e., establishment of infrastructure that links the university to society and collection of information on career paths for physical education majors). Moreover, the necessity to develop career education curriculum in connection with demand of students regarding career, the lack of systematic information on career paths of physical education majors, and the lack of researches on career education for physical education majors were discussed in this study.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.723-730
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• 2013

Due to the event of hazardous chemical injection into a water storage tank in Hongseong, Chungcheongnam-do in 2012, the Korean Ministry of Environment has revised the enforcement rules of the Water Supply and Waterworks Installation Act to install surveillance equipments such as closed-circuit television(CCTV). However, the enforcement rules still do not provide concrete provision for installation of physical security equipments. Thus we studied vulnerability of small-scale water supplies in Korea and developed guidelines for the physical security system of the facilities. The guidelines include selection and recommendation of the physical security approaches and measures to detect, delay and response to the presence of an intruder in small-scale water supplies. The security features include protection utilities(e.g., fencing and fence topping), exterior intrusion detectors and alarms, locks and padlocks, surveillance utilities(e.g., CCTV), and others.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.688-692
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• 1998

To detect naturally occuring antimutagenic substances from wild mushrooms in Korea, the screening for the antimutagenic compounds containing in ethanol and water extracts of 13 wild mushrooms toward benzo(a) pyrene (B(a)P) and $N-methyl-N'-nitro-N-nitrosoguanidine\;(MNNG)$ using the Ames assay system with Salmonella typhimurium TA98 and TA100 were studied. The ethanol extracts of Polyporus dispansus, Cantharellus infundibuliformis, Agaricus subrutilescens, Daedalea dickinsii, Panaeolus papilionaceus and Hydnum repandum showed significantly antimutagenic activity toward B(a)P. The water extracts of Hydnum repandum showed the strong antimutagenic activity toward B(a)P in S. typhimurium TA100, however the water extracts of the mushrooms did not show antimutagenic activity. Whereas 5 out of 13 samples exhibited antimutagenicity toward a direct mutagen of MNNG. The water extracts from mushrooms also not showed antimutagenic activity. The antimutagenic effect increased with increasing concentraion of the ethanol extracts from Polyporus dispansus.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.234-239
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• 2013

The $M_W$ 9.0 thrust-fault earthquake has occurred in the Pacific coast of Tohoku, Japan, on March 11, 2011. We present the detection of the great earthquake and analyze T-waves associated with the main event and two other big aftershocks ($M_W$ > 7) recorded in a hydroacoustic array (H11N) in the Pacific Ocean by performing array and spectral analysis to examine characteristics of T-waves generated from the big events. The complex rupture process of the main event directly influences on the shape of the T-waves, and the peak locates on where T-waves excited from fast rupturing process arrive. We compare the two aftershocks with different fault type and show that the fault type and the source depth change shape and spectral contents of T-waves.

• Electronics and Telecommunications Trends
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• v.24 no.6
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• pp.99-109
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• 2009

현재 주목을 받고 있는 테라헤르츠 대역의 주파수를 이용한 무선통신시스템 응용기술 동향에 대하여 기술한다. 테라헤르츠 대역은 전자파 스펙트럼에서 밀리미터파 대역과 원적외선 대역의 중간에 위치하는 100GHz~10THz 사이의 주파수이다. 현재 시점에서 10년 이내에 약 15Gbps의 데이터 속도가 필요할 것으로 판단되며, 10Gbps 이상의 전송속도를 실현하기 위해서는 기존의 밀리미터파에서 사용하는 주파수 대역폭 보다 더 넓은 대역폭이 필요하며, 이 대역폭을 얻기 위해서는 테라헤르츠 주파수 대역으로 자연적으로 옮겨가지 않을 수 없다. 본 고에서는 테라헤르츠 대역의 전파 특성, 가용 주파수 대역과 무선통신시스템 응용을 위한 옥내 채널 모델, 테라헤르츠 무선통신시스템 연구동향, RF 송수신기 핵심부품 및 MMIC 기술개발 동향을 소개하고자 한다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.296-300
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• 2003

Design of drawing dies used in real industrial environments. It was designed by CAD software in many small & medium companies, but many products require various types, and sizes. Therefore, many companies are required to reduce process time and design mistakes. In this paper, for the automatic design of drawing dies, Design process considered that easy to team and use. which are used with Visual LISP/DCL language in a commercial CAD package, AutoCAD. It has adopted GUI in design system, and has applied DCL language. The system is based on the knowledge base system which is involved a lot of expert's know-how We have built database of design type and detail sizes. The automatic design system requires basic product type and sizes. Then the system accesses to the database and find out sizes by comparing with input parameters and generate drawing dies file.

• Journal of KSNVE
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• v.7 no.1
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• pp.55-60
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• 1997

In order to examine the validity of an asymptotic solution obtained from the method of multiple scales, we investigate a third-order subharmonic resonance response of a bar constrained by a nonlinear spring to a harmonic excitation. The motion of the bar is governed by a linear partial differential equation with a nonlinear boundary condition. The nonlinear boundary value problem is solved by using the finite difference method. The numerical solution is compared with the asymptotic solution.