• Journal of Advanced Navigation Technology
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• v.20 no.2
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• pp.134-140
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• 2016

This paper analyzed flight trajectory characteristics of ballistic missiles considering effects of drag forces. It is difficult to intercept ballistic missiles which fly over atmosphere with supersonic speeds and small radar cross section (RCS). In particular, the velocities in the phases of boost and terminal are changed significantly due to the steep variation of the drag force. Therefore, in order to build up a successful ballistic missile defense systems, the effects of the drag forces should be considered in the analysis of ballistic missile trajectory characteristics. In this point of view, this work analyzed the effects of drag forces and derived the flight trajectory characteristics of Scud B, C and Nodong missiles. Model of the ballistic missile flight trajectory is considered the effects of Coriolis and centrifugal forces, and specifications of the missiles are open sources.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.6
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• pp.487-497
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• 2019

It is very difficult to detect ballistic missiles because of small cross-sections of the radar and the high maneuverability of the missiles. In addition, it is very difficult to recognize and intercept warheads because of the existence of debris and decoy with similar motion parameters in each flight phase. Therefore, feature vectors based on the maneuver, the micro-motion according to flight phase are needed, and the two types of features must be fused for the efficient recognition of ballistic warhead regardless of the flight phase. In this paper, we introduce feature vectors appropriate for each flight phase and an effective method to fuse them at the feature vector-level and classifier-level. According to the classification simulations using the radar signals predicted by the CAD models, the closer the warhead was to the final destination, the more improved was the classification performance. This was achieved by the classifier-level fusion, regardless of the flight phase in a noisy environment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.280-287
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• 2010

The first Korean satellite launch vehicle, KSLV-I(Korea Space Launch Vehicle-I), was launched for its first flight test on Aug. 25, 2009 from Naro Space Center located in south Jolla province. Because launch vehicles usually fly long range with large amount of propellants aboard, preparation of countermeasures against potential malfunctions during flight is essential in launch operation. In this paper, the flight safety operation, prepared to guarantee flight safety during launch operation of KSLV-I, is presented. Prior to flight test, flight safety analysis is performed to estimate associated risk levels quantitatively, and during flight, flight safety systems are operated to cope with any risky situations. Real-time flight monitoring including computation of instantaneous impact point using tracking data is executed normally and the flight test is completed without activation of flight termination system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.41-44
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• 2006

The propulsion system of VIA-50A airship consists of engine, generator, inverter, motor and propeller. The motor and propeller was designed that can be tilted to $120^{\circ}$ for thrust vector control. When the flight test was performed, various condition data of the airship were obtained by wireless telecommunication and analyzed in real-time. In this paper, we presented flight test results of propulsion system. Considering the designed requirement and normal range, we verified that all constituent part was operated in normal condition during the high altitude flight test.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.10a
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• pp.14-14
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• 1999

액체 램제트 엔진의 특성은 흡입구를 통해 들어오는 유입공기의 상태에 따라 많이 달라진다. 흡입구에 들어오는 공기의 유입각이 일정각도를 넘어서면 유입공기의 왜곡이 심하여 정상적인 연소가 불가능 할 수 있다. 따라서 다양한 비행조건에 따른 램제트 엔진의 특성을 파악하기 위하여 외부 유입영역, 흡입구, 연소기, 노즐 및 출구 대기 영역을 함께 계산하여 유동 특성과 연소 특성을 파악하고자 하였다. 흡입구는 마하 2.0을 기준으로 설계하고, 4각 덕트에서 완만하게 원형 덕트로 변화되는 확대관의 형상으로 비행체에 붙어 있는 것으로 격자를 구성하였다. 흡입구에서의 유동 조건은 비행체을 지난 유속이 마하 2.0과 2.2의 경우에 대하여 수치 실험을 수행하였으며, 비반응 유동 해석과 연소가 있는 반응 유동해석 결과를 흡입구를 포함하지 않았던 선행 연구 결과들과 비교하였다. 유입각이 영 일 때의 흡입구를 포함한 계산 결과는 흡입구에서 생성되는 충격파에 의한 손실로 총압력이 흡입구를 포함하지 않았던 선행 연구 결과와 차이가 있었으나 유동 특성에는 큰 차이가 없었다. 그러나 유입각이 증가함에 따라 흡입구로 유입되는 공기의 량이 감소하고 그에 따른 유동의 왜곡이 심하여 연소특성에 변화를 보여 주었다.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.104-113
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• 2019

There are keen competitions among the air operators to recruit competent pilots, which could be adversely affect the safe operation of aircraft. This study is aimed to identify the correlation between the flight experience of the pilot of the air transport operator and competency on visual approach operation. About 2,400 sets of flight training data of several pilots of an air transport operator was analysed for this study. The analysis showed that most captains were able to make stabilized visual approach regardless of his/her flight experience of any type of aircraft, while the first officers were able to make a stabilized visual approach with more than 1,500 hours of flight experience for each rated type of aircraft. This should be considered during making policies for the supply and demand of pilots for the safe operation of air transport.

• Proceedings of the Korea Society for Simulation Conference
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• 2004.05a
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• pp.131-135
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• 2004

Landing gear force reaction module is important for aircraft take off and landing simulation. But usually this modulo is not accounted for control law design simulation. because it does not affect the flying quality of aircraft. Now a days, this module is getting more important according to the increase of needs for training purpose simulation and specific control law design such as unmaned aircraft landing on the moving platform. In this paper 1DOF mass spring simple force system per gear was accepted.

• 한국사회정책
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• v.24 no.2
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• pp.127-155
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• 2017

The physical and psychological weaknesses of delinquent adolescents increase the possibility of socialization and the possibility of social exclusion. Therefore, this study aims to clarify the characteristics of the social exclusion through the Q methodology and to suggest policy and practical intervention directions. For this purpose, 36 statements about social exclusion were conducted through 15 prejudicial adolescents with the prior cooperation of the institution and the consent of the subjects. As a result of the analysis, four types were derived. Type 1 can be named as social disconnect type 'Type 2 is total type', type 3 is 'poverty type' and type 4 is 'service type'. Based on this, it can be said that the characteristics of social exclusion of juvenile delinquents are complexity, inclusivity, individuality, universality.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.1-9
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• 2011

Researches on hypersonic aircraft technologies have been carried out to increase flight speeds. However, increase in flight speeds causes heat loads that could lead structural change of aircraft's component. Researches on cooling technologies using endothermic fuels are progressing in the USA, France and Russia to treat the heat loads. Endothermic fuels are liquid hydrocarbon aircraft fuels which are able to absorb the heat loads by undergoing endothermic reactions, such as thermal and catalytic cracking. In this study, methylcyclohexane, n-octane, and n-dodecane were selected as model endothermic fuels and experiments in endothermic properties were implemented. Experimental conditions were supercritical condition of each model fuels in which actual endothermic fuels were exposed. The object of this study is to identify endothermic properties of the model endothermic fuels and to predict endothermic properties of actual fuels such as kerosene fuels.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.34-34
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• 1998

차세대 비행체가 갖추어야 할 요건으로 다양한 작동 범위에서 다목적으로 사용될 수 있어야 한다는 점이다. 비행체는 작전시 초음속으로 순항해야 하며, 폭탄으로 손상된 비행장에서도 이륙하여 작동할 수 있도록 짧은 이륙과 착륙 거리를 가져야 하기 때문에 현재 비행체보다 더 큰 받음각에서 작동하여 비행시 뛰어난 기동성을 가져야 한다. 제어력을 향상시키기 위해서 받음각과 동압에 의존하지 않고 큰 제어 모멘트를 제공하는 차세대 방법은 엔진의 배기가스를 원하는 비행 방향으로 제어하는 것으로 이러한 방법을 추력 편향 제어(Thrust Vector Control)라고 한다. 기존 공력에 의한 비행 자세제어 방법은 속도의 2승에 비례하는 제어력을 발생하지만, 실속을 피해야하기 때문에 공기력을 이용한 날개 및 비행체의 받음각에 한계가 있어 비행체의 선회능력을 제한하며 고공에서 저속비행 하는 경우에는 공기의 밀도가 낮고 동압이 작게 작용하여 선회능력은 낮아진다. 그러나, 추력 편향 장치는 공력을 이용하지 않고 추력을 이용하기 때문에 실속에 의한 제한이 없어 큰 받음각(70$^{\circ}$-90$^{\circ}$)으로 선회할 수 있어 월등한 기동성을 발휘할 수 있다. 이러한 추력 편향 장치 중 제트 베인형은 소형화가 가능하고, 하나의 노즐로 수직, 수형 및 횡 방향의 3축 제어를 할 수 있어 많이 사용되고 있다.