• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.12
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• pp.1193-1200
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• 2008

The procedure of design for reliability which consists of reliability analysis and Failure Modes and Effects Analysis(FMEA) is established and reliability assesment is performed for the nano-satellite air-launching rocket, Mirinae II. By means of using the reliability analysis result, the feasibility to insert the Mirinae II to the target orbit for given mission time under operating environment is assessed. During the reliability analysis process, the system is categorized by Work Breakdown Structure(WBS), and reliability structure is defined by both Reliability Block Diagram(RBD) and schematics of the system. FMEA is used to determine the risk priority number of components and parts. The target reliability is satisfied by changing the design of components and parts with high-risk, hence the design for reliability to put the satellite in to the target orbit safely has been performed.

• Journal of the Korean Society of Systems Engineering
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• v.3 no.2
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• pp.33-38
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• 2007

This paper describes a basic process of reliability analysis in shipped guided weapons. The OMS/MP provides originating data for RAM analysis. However, The process of reliability analysis is often done with an insufficient understanding of OMS/MP. This work proposed the improved reliability analysis process with Relax. It is shown that the process is applicable to shipped guided weapons.

• Proceedings of the Korea Contents Association Conference
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• 2014.11a
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• pp.247-248
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• 2014

국제투명성 기구가 발표한 우리나라 부패인식 지수는 2008년을 기점으로 매년 하락하는 추세를 보이고 있으며, 지난 2013년 55점(세계 46위, OECD 34개국 중 27위)를 나타내고 있다. 현대사회에서 공직자의 부패문제는 과거부터 꾸준히 제기되어온 해결과제라고 할 수 있으며, 최근 몇 년간의 문제만은 아니라는 것을 의미한다. 다산 정약용의 저서 "목민심서" 율기육조 중에서 제2조 청심에서 청렴은 수령의 기본임무이고, 모든 선의 근원이요 모든 덕의 근본이니, 청렴하지 않고서 수령 노릇을 할 수 있는 자는 없다고 하였다. 이는 공직사회의 청렴성을 중요시 하는 것으로 현대사회를 살아가는 공직자에게 귀감이 된다고 할 수 있을 것이다. 그러나 최근 경찰공무원의 청렴성이 대중매체의 도마에 끊임없이 회자되며, 이는 경찰조직구성원 전체에 대한 신뢰를 저하시키는 요인으로 작용되고 있다. 따라서 본 연구에서는 경찰부패와 청렴도 제고에 관련되는 선행연구를 검토하고, 경찰조직의 내 외적 환경에서의 청렴도 제고를 저해하고 있는 문제점을 도출하여, 이에 관한 개선방안을 제시하도록 하였다.

• Journal of the Korea Convergence Society
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• v.10 no.3
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• pp.31-37
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• 2019

In this paper, we propose an approach to get the requirement of drone acquisition for the efficient dronebot combat system using brute force algorithm. We define parameters, such as width, depth, and important surveillance area for the surveillance mission in the Army battalion and company units based on real military operation environment and brute force algorithm with 4 steps including first, next, valid, output is applied to get the requirement of drone acquisition and each drone's path planning using computer simulation. As a result, we could get the requirement of drone acquisition and each drone's path planning, the Army could utilize our proposed approach in the Army dronebot combat system. In the future research, we will study on the reliability of our proposed approach to get the requirement of drone acquisition for the efficient dronebot combat system.

• Journal of Applied Reliability
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• v.11 no.4
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• pp.433-445
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• 2011

Duty cycle is determined as the ratio of operating time to total time. Duty cycle in reliability prediction is one of the significant factors to be considered. In duty cycle application, non-operating time failure rate has been easily ignored even though the failure rate in non-operating period has not been proved to be small enough. Ignorance of non-operating time failure rate can result in over-estimated system reliability calculation. Furthermore, utilization of duty cycle in reliability prediction has not been evaluated in its effectiveness. In order to address these problems, two reliability models, such as MIL-HDBK-217F and RIAC-HDBK-217Plus, were used to analyze non-operating time failure rate. This research has proved that applying duty cycle in 217F model is not reasonable by the quantitative comparison and analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.95-100
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• 2003

Electronic equipment used in satellites are demanding extremely high reliability, so they should be designed to have immunity for some critical faults by using redundancy component. Generally, Communication satellites are assigned to meet the 15 years mission lifetime, of the analysis about faults must be performed to electronic equipments of satellite. This paper is a summary of the fault tolerance design research of command processor, the improvement of reliability and trade-off study of fault tolerance design result. The reliability prediction value of the satellite component used in this research was taken from Koreasat 3 and Kompsat 1. It is important to perform many trade-off studies for fault tolerance design, especially to choose the most proper fault tolerance method for the specified fault scenario.

• Journal of Industrial Convergence
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• v.18 no.3
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• pp.19-25
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• 2020

In the software development process, software reliability evaluation is a very important issue. In particular, finding the optimal development model that satisfies high reliability is the more important task for software developers. For this, in this study, Pareto and Erlang life distributions were applied to the finite failure NHPP model to evaluate the reliability attributes. For this purpose, parametric estimation is applied to the maximum likelihood estimation method, and nonlinear equations are calculated using the bisection method. As a result, the Erlang model showed better performance than the Pareto model in the evaluation of the strength function and the mean value function. Also, as a result of inputting future mission time and evaluating reliability, the Erlang model showed an effectively high trend together with the Pareto model, while the Goel-Okumoto basic model showed a decreasing trend. In conclusion, the Erlang model is the best model among the proposed models. Through this study, it is expected that software developers will be able to use it as a basic guideline for exploring and evaluating the optimal software reliability model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.428-434
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• 2020

The one-shot weapon system is destroyed after only one mission. So, the system requires high reliability. Guided missiles are one-shot weapon systems that have to be analyzed by storage reliability since they spend most of their life in storage. The analysis results depend on the model and the ratio of correct censored data. This study was conducted to propose a method to more accurately predict the future failure rate of Air force guided missiles. In the proposed method, the failure rate is predicted by both MTTF (Mean Time To Failure) and MTBF (Mean Time Between Failure) models and the model with a smaller error from the real failure rate is selected. Next, with the selected model, the ratio of correct censored data is selected to minimize the error between the predicted failure rate and the real failure rate. Based on real field data, the comparative result is determined and the result shows that the proposed sampling rate can predict the future failure rate more accurately.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.437-443
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• 2014

Engine is one of the most important parts in a rocket for completing its mission successfully. In this paper, we provide a methodology for estimating reliability and development cost of a liquid rocket engine newly developed. To estimate reliability, a baseline engine is selected considering factors whose effects on reliability are unquantifiable. Then reliability of a baseline engine is adjusted to reflect the effect of factors that can be modeled quantitatively. Using the previous Transcost engine cost expressed in terms of mass and the number of hot firing tests, the engine development cost is reexpressed in reliability and thrust requirements. Finally, a numerical example is given to illustrate the application of the methodology to a turbopump rocket engine using staged combustion cycle with LOX/LH2 propellant.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.1
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• pp.9-16
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• 2023

Robots are expected to expand their scope of application to the military field and take on important missions such as surveillance and enemy detection in the coming future warfare. Swarm robots can perform tasks that are difficult or time-consuming for a single robot to be performed more efficiently due to the advantage of having multiple robots. Swarm robots require mutual recognition and collaboration. So they send and receive vast amounts of data, making it increasingly difficult to verify SW. Hardware-in-the-loop simulation used to increase the reliability of mission verification enables SW verification of complex swarm robots, but the amount of verification data exchanged between the HILS device and the simulator increases exponentially according to the number of systems to be verified. So communication overload may occur. In this paper, we propose a digital twin-based communication optimization technique to solve the communication overload problem that occurs in mission verification of swarm robots. Under the proposed Digital Twin based Multi HILS Framework, Network DT can efficiently allocate network resources to each robot according to the mission scenario through the Network Controller algorithm, and can satisfy all sensor generation rates required by individual robots participating in the group. In addition, as a result of an experiment on packet loss rate, it was possible to reduce the packet loss rate from 15.7% to 0.2%.