• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.213-223
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• 2019

This paper analyzes delta-Vs to maintain an extremely low altitude on the Moon and investigates the possibilities of performing a CubeSat mission. To formulate the station-keeping (SK) problem at an extremely low altitude, current work has utilized real-flight performance proven software, the Systems Tool Kit Astrogator by Analytical Graphics Inc. With a high-fidelity force model, properties of SK maneuver delta-Vs to maintain an extremely low altitude are successfully derived with respect to different sets of reference orbits; of different altitudes as well as deadband limits. The effect of the degree and order selection of lunar gravitational harmonics on the overall SK maneuver strategy is also analyzed. Based on the derived SK maneuver delta-V costs, the possibilities of performing a CubeSat mission are analyzed with the expected mission lifetime by applying the current flight-proven miniaturized propulsion system performances. Moreover, the lunar surface coverage as well as the orbital characteristics of a candidate reference orbit are discussed. As a result, it is concluded that an approximately 15-kg class CubeSat could maintain an orbit (30-50 km reference altitude having ${\pm}10km$ deadband limits) around the Moon for 1-6 months and provide almost full coverage of the lunar surface.

• Journal of Digital Convergence
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• v.4 no.1
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• pp.9-16
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• 2006

Function Point(FP) is well spread and advanced methodology in software costing. But FP is not common in game contents costing. It is one reason that Game Contents is a new area in software costing. And, ISO/IEC FDIS 19761(final draft) recommends not to use FP method in game contents costing. So we suggested new methodology in that area which is called Game Factor Point Method(GFPM). In this paper, we studied more about the weight of the game factor. We hope this will clarify them. We made definition of game factor, and studied more detail about Mission which was a little ambiguous in prior study. We also studied difficulties of game factor which will be a very important factor in game contents costing.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.228-231
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• 2008

For a satellite data communication, the technology of frame synchronization is widely used between a sender and a receiver. Last year, we suggested zero-loss frame synchronization [1] using pattern search and using bits threshold search algorithm that is based on SIMD technology [2,3]. This algorithm could solve both of hardware and software drawbacks, which are frame loss and low processing performance. However, this algorithm didn't optimize the processing of output data, synchronized data, which caused overhead to the memory allocation and the memory copy. Consequently, the performance of the frame synchronizer application was degraded. In this paper, we enhance previous work using a circular buffer in order to optimize the output data processing. The performance comparison with the previous algorithm shows that the enhanced proposed approach dramatically outperforms in the output data processing speed.

• Journal of Information Technology Applications and Management
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• v.11 no.3
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• pp.147-159
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• 2004

Empirical evidence on the maintainability of object-oriented systems is far from conclusive, partly due to lack of representativeness of the subjects and systems used in the study. The present research empirically examined this issue with the systems that are mission-critical. currently operational and maintained by professionals. It was found that the 00 group appeared to consume less time while maintaining more amount of software artifacts than the NOO counterpart. This economical utilization of time appeared evident regardless of software development life cycle. This was due to the usefulness of UML for impact analysis which contributed to effective comprehension and communication. Insufficient design specifications led to ambiguity and costly defects in transferring design solutions to development. Also. the encapsulation of 00 seemed to reduce mental loads at maintenance tasks and improved code reuse. However, the number of files to manage increased and thus. dependency management is required for the 00 systems.

• Journal of the Korea Society of Computer and Information
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• v.23 no.12
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• pp.115-122
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• 2018

As the proportion of software in weapon systems increases, the impact of software on the overall system is growing. As a result, software quality management becomes important, and related regulations and work manuals for quality assurance activities at each stage in the R & D process are becoming more sophisticated. However, due to the characteristics of the weapon system software that is developed as a customized form for the purpose of a specific mission, there are limits to specifying and definitizing the detailed requirements (upper and lower level) according to various operational concepts during the development process. Due to this, software modification (patch change, shape change due to upgrade, etc.) occurs on account of many defects and performance improvement in the mass production and operation stage after the development is completed. In this study, we analyze the characteristics of these weapon system softwares and propose quality improvement methods based on ISO / IEC / IEEE 29119 test method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.2
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• pp.13-20
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• 2008

Reliability is absolutely necessary in most recent mission critical systems which usually utilize the Ethernet based computer networks. A typical way to increase system reliability is to equip the fault tolerant Ethernet. In this paper we try to formulate the fault tolerant dual Ethernet concept and presents a comparison of its implementation approaches. Two types of dual Ethernet configuration are analyzed; the divided and the connected. Then the characteristics of three current implementation approaches which are the hardware based, the software based, and the recently proposed hybrid approach are compared. The results show that the hardware based or the hybrid approaches can be a better solution for the real time mission critical systems. Also for the systems which require the use of Commercial-Off-The-Shelf (COTS) hardware for fault tolerant Ethernet the possible choice is the software based or the hybrid approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.108-120
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• 2017

To this end, the ROK military is developing a Korean Tactical Data Link (Link-K) in two stages: Basic and Completion types. Currently, the basic type of the Link-K has a limitations for supporting Mission Group(MG)s, such as to share unnecessary information and inefficient routing, because all RICCs simply broadcasts the same information in the basic type of the Link-K. In this paper, we propose a Zone-based Wireless Link-K network structure and a routing algorithm. To improve the effectiveness of the proposed routing algorithm, we have studied a filtering method that adjusts the message data according to the priority of the message and a method of controlling the load of the network. In order to evaluate the performance of the proposed scheme, it is proved that it is effective to support the mission task group compared with the existing wireless Link-K routing algorithm according to the operational scenario situation.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.2
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• pp.1-10
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• 2013

In this paper, make a study decision problem called an optimal release policies after testing a software system in development phase and transfer it to the user. In the course of correcting or modifying the software, finite failure non-homogeneous Poisson process model, presented and was proposed release policies of the life distribution, half-logistic and log-logistic distributions model which used to an area of reliability because of various shape and scale parameter. In this paper, discuss optimal software release policies which minimize a total average software cost of development and maintenance under the constraint of satisfying a software reliability requirement. In a numerical example, the parameter estimation using maximum likelihood estimation of failure time data make out, and software optimal release time was estimated.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.175-178
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• 2007

COMS (Communication Ocean Meteorological Satellite) is the geostationary satellite being developed by Korea Aerospace Research Institute for multi-mission: experimental communication, ocean monitoring and meteorological observations. The COMS operation is controlled by the on-board software running on the spacecraft central computer. The software is written in ADA language and developed under the software life cycle: Requirement analysis, Design, Implementation, Component test and Integration test. Most functional requirements are tested at component level on a software component testing tool, ATTOL. ATTOL provides a simple way to define the test cases and automates the test program generation, test execution and test analysis. When two or more verified components are put together, the integration test starts to check the non-functional requirements: real-time aspect, performance, the HW/SW compatibility and etc. This paper introduces the COMS on-board software and explains what to test and how to test the on-board software at component level using ATTOL.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.460-463
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• 2007

COMS (Communication Ocean Meteorological Satellite) is the geostationary satellite being developed by Korea Aerospace Research Institute for multi-mission: experimental communication, ocean monitoring and meteorological observations. The COMS operation is controlled by the on-board software running on the spacecraft central computer. The software is written in ADA language and developed under the software life cycle: Requirement analysis, Design, Implementation, Component test and Integration test. Most functional requirements are tested at component level on a software component testing tool, ATTOL. ATTOL provides a simple way to define the test cases and automates the test program generation, test execution and test analysis. When two or more verified components are put together, the integration test starts to check the non-functional requirements: real-time aspect, performance, the HW/SW compatibility and etc. This paper introduces the COMS on-board software and explains what to test and how to test the on-board software at component level using ATTOL.