• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.6
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• pp.474-482
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• 2007

An analysis is made for flow and rocket motion during a supersonic separation stage of an air-launching rocket(ALR) from the mother plane. Three-dimensional compressible Navier-Stokes equations are numerically solved to analyze the steady/unsteady flow fields around the rocket which is being separated from the mother plane configuration(F-4E Phantom). Simulation results clearly demonstrate the effect of shock-expansion wave interaction around both of the rocket and the mother plane. To predict the behavior of the ALR by the change of the center-of-gravity, three cases of numerical analysis are performed. As a result, a design-guideline of supersonic air-launching rockets for safe separation is proposed.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.329-331
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• 2006

연료전지용으로 많이 사용되는 전불소계 고분자인 Nafion은 좋은 기계적, 화학적 안정성 및 높은 이온전도도에도 불구하고 고가의 생산단가, 높은 메탄올 투과도, 그리고 MEA 재활용 문제 등으로 인해 상업적 응용에 제한이 있다. 본 연구는 불소그룹을 함유한 술폰화된 아릴렌이서계 블록 공중합체 고분자 전해질막의 제조 및 연료전지 특성에 관한 것이다. 이러한 고분자를 제조하기 위하여 양말단에 불소계 비닐기를 가지면서, 상온에서 술폰화 가능한 biphenyl계 단량체와 술폰화가 불가능한 sulfonyl계 단량체를 각각 합성하였으며, 이들로부터 다양한 몰조성과 분자량을 갖는 올리고머를 포함한 일련의 perfluorocyclobutane기를 포함하는 블록 공중합체를 열적 고리화 부가중합을 사용하여 합성하였다. 제조된 블록 공중합체를 상온에서 술폰화제인 chlorosulfonic acid를 이용하여 선택적으로 후술폰화시켜 강산 이온기인 sulfonic acid를 블록 올리고머에 도입하였다. 합성된 고분자들의 연료전지 특성을 Nafion-115와 비교하였다. 술폰화가 되는 올리고머 블록의 비율 증가에 따라 이온교환능력이 증가하였고, 그에 따라 높은 함수율과 이온 전도도를 나타내었으며 건조 및 습윤 상태에서도 기계적 강도가 우수하였다. 최적화된 블록공중합체를 대상으로 MEA를 제조하여 연료전지 초기성능을 측정한 결과 Nafion과 유사한 전기화학적 성능을 나타내었다.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.630-638
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• 2009

In this paper, we propose a new SCADE-based integrated simulator for aircraft mid-air collision avoidance. The new simulator is designed to provide a convenient simulation environment for analyzing the limitations of the existing collision avoidance system(CAS) and for realizing more realistic collision environment into the CAS performance evaluation. Furthermore, we have developed a scenario editor for TCAS-II performance analysis to simulate actual flight environment which is difficult to experiment. The performance of the proposed simulator for typical collision scenarios is demonstrated by simulation using the proposed scenario editor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.36-40
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• 2006

An analysis is made of flow and rocket motion during a supersonic separation stage of air-launching rocket(ALR) from the mother plane. Three-dimensional compressible Navier-Stokes equations is numerically solved to analyze the steady/unsteady flow field around the rocket which is being separated from the mother plane configuration(F-4E Phantom). The simulation results clearly demonstrate the effect of shock-expansion wave interaction between the rocket and the mother plane. To predict the behavior of the ALR according to the change of the C.G., three cases of numerical analysis are performed. As a result, a design-guideline of supersonic air-launching rocket for the safe separation is proposed.

• Polymer(Korea)
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• v.24 no.2
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• pp.174-181
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• 2000

The ACF/PP-g-AN copolymers were synthesized by the irradiational grafting of acrylonitrile onto ACF/PP hybrid fabric. The synthesis of the ACF/PP-g-AN copolymer was evidenced by the band of -C=N absorption peak at 2250 $cm^{-1}$ / and amidoximation was evidenced by the band of -OH and -NH$_2$ peak at 3450 $cm^{-1}$ / on FT-IR spectrum. The optimal time for the uranium ion adsorption equilibrium on ACF/PP-g-AN copolymers was 8 days and the optimal pH was 8. The adsorption capacities of ACF/PP-g-AN copolymers increased according to the content of amidoxime and were not varied even after more than 10 times of regeneration.

• Polymer(Korea)
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• v.25 no.3
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• pp.385-390
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• 2001

The A-B-A type block copoly(ester-ether)s consisting of poly(L-lactic acid) (PLLA)(A) and poly(oxyethylene-co-oxypropylene)(B) were prepared to improve the mechanical properties and hydrolyzability of PLLA. The block copolymers showed an improved flexibility due to the incorporation of the soft segments. Then, the same copolymer has an improved anti-thrombogenicity probably due to the specific microphase separation structure in the surface. The AFM of the film of the block copolymer revealed that the surface was quite flat in comparison with that of PLLA. Therefore, the flatness of the surface may be related with the increased anti-thrombogenicity of the copolymer film.

• Spatial Information Research
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• v.6 no.1
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• pp.1-10
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• 1998

The need of aerial photographs is increasing for small area development such as facility management, site planning, residence planning, and so on. It is not an easy task, however, to take aerial photographs using an aircraft for metric photogrammetry because of the strict regulatins of flying and also photographing in Korea, as well as the cost. As one of efficient methods to take large-scale aerial photographs, we investigated the ways of photographing by a remote controlled model plane(RC plane) with a light weight non-metric camera on board. We had examined the principles of RC planes and assembled a RC plane, And test photographing was performed. Even though we obtained reasonably good stereo-pairs for the grounds and facilities using the RC plane, we found there were yet many problems to be solved, such as difficulties of RC plane control, camera focusing, and accumulation of dust on the camera lens.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.1-6
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• 2014

Though the functions and operational procedures of current ACAS-II are upgraded several times owing to technical advancement, so far the mid-air collision accidents never come to an end. Recently to solve the major issues of ACAS-II, ICAO began to develop a future ACAS (Airborne Collision Avoidance System) by the year 2015. Accordingly in order to prepare for international standardization of the future ACAS, in this paper a policy is proposed for domestic implementation of the future ACAS based on the results from studying the technical standards and future development trends of ACAS.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.72-78
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• 2003

In this paper, the feasibility study and the parametric design of hybrid motor with HTPB/LOX were conducted for micro air launch system. Design results were compared with 1st stage of Pegasus XL for verification of hybrid motor. Results showed that hybrid motor replace solid booster if Isp of hybrid motor reaches 330sec. In addition, mission analysis was established for micro air launch system, and parametric design was conducted with design variables: number of port, initial oxidizer flux, and chamber pressure. And the region of Isp was identified by parametric study which satisfied design constraints and mission analysis.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.247-255
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• 1992

Polystyrene-poly(caprolactone) (PS-PCL) block copolymer was synthesized from macroazoinitiator, and its compatibilizing effect in poly(2, 6-dimethyl-1, 4-phenylene oxide) (PPO)/poly(styrene-co-acrylonitrile) (SAN, 25wt% acrylonitrile) blend was studied. PS block and PCL block in the block copolymer had shown miscibility with PPO and SAN respectively. The dissolution of SAN into PPO domain was promoted by the addition of the PS-PCL block copolymer.