• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.791-799
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• 2020

Launched in October 2019, Northrop Grumman's MEV-1 was the world's first unmanned mission demonstrating the practical feasibility of on-orbit servicing. Although the concept of on-orbit servicing was proposed several decades ago, it has been developed to various mission concepts providing services such as orbit change, station keeping, propellant and equipment supply, upgrade, repair, on-orbit assembly and production, and space debris removal. The historical success of MEV-1 is expected to expand the market of on-orbit servicing for government agencies and commercial sectors worldwide. The on-orbit servicing essentially requires the utilization of a highly propellant efficient electric propulsion system due to the nature of the mission. In this study, the space mission analysis for a simple on-orbit mission involving Hall thruster is conducted, which is life extension mission for geostationary orbit satellites. In order to analyze the mission, design space exploration for various Hall thruster design variable combinations is performed. The values of design variables and operational parameters of Hall thruster suitable for the mission are proposed through design space analysis and optimization, and mission performance is derived. In addition, the direction of further improvement for the current on-orbit mission analysis process and space mission analysis involving Hall thruster is reviewed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.10
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• pp.871-877
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• 2021

Aircraft defects are important matters directly related to the operation of the aircraft and the life of the pilot. The defects in the mission software that occur during aircraft control seriously affect the pilot's mission performance and safety. Therefore, the organization in charge of aircraft development or software defects are reinforced in the process to identify and eliminate defects in the early stages of development, and a lot of labor and time are spent, but due to the nature of the mission software, strong functional coupling with other avionics and high complexity, so there are restrictions on the identification and removal of software defects through the existing test method. This study analyzes the effect of securing mission software integrity and reducing test cost through data integrity verification by developing a tool that automates the verification of expected value of feedback data among communication data of mission computer interlocking equipment.

• Journal of the Korean Society of Systems Engineering
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• v.16 no.1
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• pp.25-35
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• 2020

The South Korean Navy is making efforts to acquire vessels that the new technology of the 4th industry is applied, and as a part of these efforts, it has a plan to mount and operate an Unmanned Surface Vehicle(USV) on a vessel that will be introduced later. However, the recent studies have focused on only development of common platforms and mission equipment for the USV, and have not sufficiently analyzed studies and operatinoal requirements on mother ship that will operate the mounted USV. Hence, this study analyzed and presented requirements of mother ship with the mounted USV in order to operate effectively it when the future medium and large vessels to be acquired by the South Korean Navy intent to operate the USV.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1355-1362
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• 2000

Microstrip antennas are attractive for many applications because of their compact size, low profile, and light weight. Recently, the demand for the miniaturization of the personal communication equipment has been increasing along with the proliferation of personal communication systems. Thus, the development of small antenna has been highly demanded. In this paper, a new technique to reduce the overall dimension of a microstrip antenna with a locally non-homogeneous substrate configuration is proposed. The miniaturized microstrip antenna for a repeater system in a mobile communication cellular band(824~894 MHz) is designed with the proposed technique, and commercialized with low cost, light weight, and small size. Comparison between simulations, based on Agilent Technologies HFSS software, and measurements are provided. The proposed method will be more attractive for a light-weight, small-size, and low-cost microstrip array design. This paper also presents the bandwidth improvement technique for under-coupled microstrip patch antenna with a tuning stub.

• Journal of Astronomy and Space Sciences
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• v.36 no.2
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• pp.69-74
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• 2019

Spacecraft requires sufficient power in orbit to perform its mission. So as to comply with system requirements, the sufficient power should be made by a solar cell array by photovoltaic power conversion. A life time of space program depends on its mission considering parts reliability and parts grade. Based on the mission life time, power equipment might be designed to meet specifications. In outer space, solar cell array might generate the dc power by photovoltaic conversion effects and GaInP/GaAs/Ge solar cells are used in this study. Space programs that require more than five years should select parts for high reliability applications. Therefore, reliability analysis for high reliability applications should be performed to check its fulfilment of the requirements. This program should also require more five years for its mission and we performed its analysis using parts count method (PCM) for its reliability. Finally, we performed reliability analysis and obtained quantitative figures found out 99.9%. In this study, we presented the reliability analysis of the 300 W GaInP/GaAs/Ge solar cell array.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.451-458
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• 2019

Reliability in the course of weapons system development and operation is a key measure of the ability of a system to perform the required functions under specified conditions over a specified period of time, and the mission confidence for the assessment of mission fulfillment is an important indicator of victory or defeat in a battle. Mission reliability indicates the probability that a given task will succeed or fail in an event or environmental situation over a given period of time. The existing mission reliability was calculated after creating a confidence blow map with only physical connections based on the mission. However, as modern weapons systems evolve and advance, the related equipment structure becomes increasingly complex, making it impossible to express mission relevance when mission classification is required based on functional or physical connections. In this study, the mission reliability was calculated for a gun control system, which is part of a ship's combat system, by expressing the association between the physical and functional structures using the design structure matrix technique and the interface matrix technique. We expect the study results to be used as verification data for mission reliability.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2407-2409
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• 2005

As the cumulative amount of spent fuel increases, the reliable and effective management of the spent fuel has become a world-wide mission. For this mission, KAERI is developing the Advanced Spent Fuel Conditioning Process (ACP) as a pre-disposal treatment process for spent fuel. Conventional approach to the development of the process and the remote operation technology is to fabricate the process equipment on the same scale as the real environment and demonstrate the remote handling operation using simulated fuel called a mock-up test. But this mock-up test is expensive and time consuming, since the design may need to be modified and the equipment fabricated again to account for the problems found during a testing. To deal with this problem, we developed a digital mockup for the ACP. Also, for an effective utilization of the digital mockup, we developed user interface modules such as the data acquisition and display module and the external input device interface module. The result of this implementation shows that a continuous motion of the manipulator using the external device interface can be represented easily and the information display screens responded well to the simulation situation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.623-628
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• 2012

Mission Equipment Package(MEP) system is a collection of avionic components that are integrated to perform the mission of the Korean Utility Helicopter(KUH). Built In Test(BIT) reduces the need for skilled personnel and special test equipment, and reduces maintenance down-time of system. The increasing complexity of avionics equipments has resulted in an increased need to provide BIT functions. This paper describe the development and verification for the KUH MEP system BIT.

• Journal of Korean Society for Quality Management
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• v.41 no.3
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• pp.405-412
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• 2013

Purpose: In this paper, the improvement of the image quality is investigated. The image quality is degraded by the drift phenomenon of EO/IR (Electro-Optical/Infrared) device on UAV. The drift phenomenon means that the image of EO/IR equipment on UAV(Unmanned Aerial Vehicle) moves to the unintended direction. This phenomenon should be improved for successful flight mission. Methods: To improve the drift phenomenon, the drift compensation method, the combination algorithm of FMC(Forward Motion Compensation) and AMC(Angular Motion Compensation) method, are introduced to calculate pitch and azimuth angle. Result values of pitch and azimuth angle are used for the improvement of image quality in EO/IR control logic. Results: The image quality is quantitatively improved more than 15 times through field test data of flight. Conclusion: Using the drift compensation technique, the image quality for EO/IR equipment is improved over 15 times than existing methods. This means the user of UAV with EO/IR device can perform a successful mission by keeping the line of sight for the target accurately.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.53-64
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• 2021

Wargame is a simulated military operation with certain rules, specifications, and procedures, in which soldiers can virtually and indirectly experience the war. The ROK Navy operates the Cheonghae model, a training wargame model for helping commanders and staff master the procedures for conducting the war. It is important for commanders, staff and analysts to know whether a warship can perform its missions and how long it can last during a war. In existing model, the Cheonghae, the probability of kill of a warship is calculated simply considering the number of tonnage without any stochastic elements, and the warship's mission availability is also determined based on predetermined values. With this model, it is difficult to get a value of the probability of kill that makes sense. In this dissertation, the author has developed a probabilistic model in which the warship vulnerability data of ROK-JMEM can be used. A conceptual model and methodology that can evaluate the mission performance of personnel, equipment, and supplies has been proposed. This can be expanded to a comprehensive assessment of wartime warship loss rates by integrating damage rates for personnel, equipment, and supplies in wartime.