• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.119-143
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• 2021

Selecting liquid methane as fuel is a prevailing trend for recent rocket engine developments around the world, triggered by its affordability, reusability, storability for deep space exploration, and prospect for in-situ resource utilization. Given years of time required for acquiring a new rocket engine, a national-level R&D program to develop a methane engine is highly desirable at the earliest opportunity in order to catch up with this worldwide trend towards reusing launch vehicles for competitiveness and mission flexibility. In light of the monumental cost associated with development, fabrication, and testing of a booster stage engine, it is strategically a prudent choice to start with a low-thrust engine and build up space application cases.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.111-122
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• 2018

The private sector is currently reviewing the feasibility of the project or deciding economic policies by analyzing the economic ripple effects. However, the arms acquisition project focuses on the need for the national defense weapons system by analyzing the costs and the effectiveness of the analysis and reviewing the necessity and feasibility of the project. In order to analyze the economic ripple effects, KB (the Bank of Korea) prepares and publishes an analysis table of industrial associations in a given unit. IAAR (the industrial association analysis report) is difficult to apply directly to the defense weapons system. Therefore, research on the economic ripple effects applicable to the defense arms procurement project was needed. In this study, we propose the generic methodology for estimating economical and technical ripple effects resulted in acquiring new weapon systems. Based on the analysis of inter-industrial relations, economical ripple effects are estimated with production inducing effects, value-induced effects, employment-induced effects and export-induced effects. Also, the technological ripple effects are estimated with technological intensity represented by investment cost in research and development. To show the validity of proposed methodology, a case study of acquiring new weapon systems such as GR (guided rocket), destroyer, and helicopter is accomplished. From the case study, it is concluded that these economical & technological ripple effects can be used as a reference to decision making in the course of acquiring major future defense weapons systems.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.10
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• pp.888-893
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• 2012

This paper described the wind tunnel testing apparatus and technique to acquire the dynamic stability derivatives of large slenderness ratio air vehicle such as the guided missiles or rockets. There have been few difficulties in conducting wind tunnel testing for slender long rocket due to the size limitation of the test section size and the installation of oscillation equipments. In this study, the dynamic stability balance was used as the wind tunnel technique for obtaining the dynamic stability derivatives. Through the wind tunnel testing, the experimental apparatus for slender air vehicle's oscillation is established. The measured data showed that it is possible to acquire the dynamic stability derivatives of large slenderness ratio rocket, properly.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.6
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• pp.74-86
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• 2021

The composite lattice structure is a structure that supports the required load with the minimum weight and thickness. Composite lattice structure is manufactured by the filament winding process using impregnating high-strength carbon fiber with an epoxy resin. Filament winding process can laminate and manufacture only structurally necessary parts, composite lattice structure can be applied to aircraft fuselages, satellite and launch vehicles, and guided weapons to maximize weight reduction. In this paper, the development and evaluation of the composite lattice structure corresponding to the entire process from design, analysis, fabrication, and evaluation of large-scale cylindrical and conical composites lattice structure were performed. To be applicable to actual projectiles and guided weapons, we developed a cylindrical lattice structure with a diameter of 2,600 mm and a length of 2,000 mm, and a conical lattice structure with an upper diameter of 1,300 mm, a lower diameter of 2,500 mm, and a length of 900 mm. The performance of the developed composite lattice structure was evaluated through a load test.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.361-365
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• 1991

The problem being considered here is the determination of optimal guidance laws for a launch vehicle for scientific missions. The optimal guidance commands are determined in the sense that the least amount of fuel is used. A numerical solution was obtained for the case where the position and velocity state variables satisfy a specified constraint at the time of thrust cutoff. The method used here is based on the Pontryagin's maximum principle. This is the method of solving a problem in the calculus of variations. In particular, it applies to the problem considered here where the magnitude of the control is bounded. Simulations for the optimal guidance algorithm, during the 2nd and the 3rd-stage flight of the Japanese rocket M-3H-3, are carried out. The results show that the guided trajectory that satisfying the terminal constraints is optimal, and the guidance algorithm works well in the presence of some errors during the 1st-stage pre-programmed guidance phase.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.309-312
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• 2007

The cryogenic fluid is the propellant for the liquid rocket engine. The design of space launcher vehicle is guided by minimum size and weight criteria, so the turbo pump solicits high impeller speed. Such high speed results in a zone of pressure drop below vapor pressure causing caivtation around inducer blades. The cryogenic fluid has different characters from isothermal fluid like water. The cryogenic fluid has very sensible thermodynamic properties and the phase change undergoes evaporative cooling. So, the developed code has to be modified cavitation modeling and it is added the energy equation for temperature sensitivity.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.533-540
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• 2014

We propose an age estimation-based smart digital signage for the next-generation airport service. The proposed system can recognize the face of the customer so that it can display the selective information. Using a webcam, the system captures the face of the customer and estimates the age of the customer by calculating the wrinkle density of the face and applying bayesian classifier. The developed age estimation method is tested with a face database for the performance evaluation. We expect the new digital signage may improve the satisfaction of customers of the airport business.

• Journal of Convergence for Information Technology
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• v.11 no.6
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• pp.113-119
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• 2021

Since the weapon system project has a large ripple effect on the country by investing a huge budget, analysis of acquisition methods that secured economic feasibility is required in the planning stage to promote the weapon acquisition project. In response to this demand, economic analysis for acquisition method is preformed in the research stage of previous studies, but the analysis on economic analysis for acquisition alternative is imperfect at the present. In this research, we identify the limitations of the effect analysis and propose an additional cost-benefit analysis method to analyze the economic feasibility of the acquisition alternative. It is possible to present the universal results of economic feasibility analysis for not only multiple alternatives but also single alternatives by presenting benefit/cost ratio. It is applied to research on acquisition project of OO guided rocket, and the result of economic analysis for each alternative is presented.