• Journal of the Korean Society of Systems Engineering
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• v.10 no.2
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• pp.51-58
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• 2014

Manufacturing industry is one of the core sectors providing national competitiveness and economical impact Today's manufacturing industry is required to fulfill so called Sustainable Factory paradigm from the perspectives of environmental and social development. To cope with the requirements, researches for achieving sustainability in manufacturing system are actively carried out in the world from various perspectives. In this paper, we analyzed systemic characteristics of sustainable manufacturing system, and developed verification & validation strategy based on traceability between system requirement and functionality. The developed methods were applied to a European Project called the Foundation for the Sustainable Factory of the Future (FoFdation). Specifically, we analyzed and verified the deliverables of FoFdation by deriving systems architecture in terms of Component, Function, and Items. The results indicated that the FoFdation is pretty much compliant with the concept of Ubiquitous Factory, and can be used as an International Reference Model for the Smart Factoy, a world wide hot topic under the paradigm of IOT (Internet-Of-Things), if information processing part is supplemented.

• Journal of the Korean Society of Systems Engineering
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• v.4 no.2
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• pp.55-61
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• 2008

In this paper, there is the case study which assesses the systems engineering capability maturity of the safety organization that performs the Railway Safety project using systems engineering method. To In ore effective and efficient a research and development to railway safety domain, a new research and development method can be progressively needed such as systems engineering. To assess quantitatively research of systems engineering efforts in the railway safety project, SECM(EIA/IS 731) Standard is utilized in the paper. It is by questionnaire that the capability maturity assessment is executed wit h the safety organization and staffs who performs the systems engineering activities; requirement analysis and management, interface control management. product verification and validation, and so on. As a result, the systems engineering capability level of the safety organization rises from 0 level at the initial project to 2 level after two years and all staffs give an affirmative answer about the importance and effectiveness of the systems engineering approach.

• Journal of Advanced Navigation Technology
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• v.5 no.2
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• pp.149-157
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• 2001

A high speed data link capability is one of the critical factors in determining the performance of the spaceborne SAR system with high resolution. It is due to the strict requirement for the real-time data transmission from a series of massive raw image data of spaceborne SAR to the ground station in a limited time of mission. In this paper, based on the data link model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.3
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• pp.25-32
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• 2006

Weapon systems composed of several subsystems execute various engagement missions in distributed combat environments in cooperation with a large number of subordinate/adjacent weapon systems as well as higher echelons through tactical data links. Such distributed weapon systems require distributed real-time simulation test beds to integrate and test their operational software, analyze their performance and effects of cooperated engagement, and validate their requirement specifications. These demands present significant challenges in terms of real-time constraints, time synchronization, complexity and development cost of an engagement simulation test bed, thus necessitate the use of high-performance distributed real-time simulation architectures, and modeling and simulation techniques. In this paper, in order to meet these demands, we presented a distributed real-time simulation system based on High Level Architecture(HLA) and Discrete Event System Specification(DEVS). We validated its performance by using it as a test bed for developing the Engagement Control System(ECS) of a surface-to-air missile system. The proposed technique can be employed to design a prototype or model of engagement-level distributed real-time simulation systems.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.275-278
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• 1997

Standard methods estimating the power spectral density(PSD) from an irregularly sampled cardiac event series require deriving a new evenly-spaced signal applicable to those methods. To avoid that requirement, in this study, the power spectrum of heart rate variability was estimated by Lomb-Scargle's algorithm, which is a means of obtaining PSD estimates directly from irregularly sampled timeseries observed in astronomy. To assess the performance of Lomb-Scargle algorithm in the power spectral analysis of heart rate variability, it was applied to various cardiac event series derived through integral pulse frequency modulation model(IPFM) simulation and from real ECG signals, and the resultant power spectra was compared with those obtained by a conventional method based on the FFT. In result, it is concluded that Lomb-Scargle's periodogram is very effective in the power spectral analysis of heart rate variability, especially in the presence of arrhythmia and/or dropouts of cardiac events.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.88-90
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• 2011

The IHO(International Hydrographic Organization) has developed the S-100 standard as a universal hydrgraphic data model for consistent use and application of various hydrographic data and sources, and is developing the product specification standards. The organization modified this standard to reflect the requirements of application parts, detailed the insufficient contents for products. In this study, the trend and recent requirement of S-100 standard were analyzed. Also, a method of managing S-100 standard was completed based on the analysis of S-100 application.

• Journal of Communications and Networks
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• v.8 no.1
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• pp.116-122
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• 2006

Most of the multimedia applications require strict quality of service (QoS) guarantee during the communication between a single source and multiple destinations. This gives rise to the need for an efficient QoS multicast routing strategy. Determination of such QoS-based optimal multicast routes basically leads to a multi-objective optimization problem, which is computationally intractable in polynomial time due to the uncertainty of resources in Internet. This paper describes a network model for researching the routing problem and proposes a new multicast tree selection algorithm based on genetic algorithms to simultaneously optimize multiple QoS parameters. The paper mainly presents a QoS multicast routing algorithm based on genetic algorithm (QMRGA). The QMRGA can also optimize the network resources such as bandwidth and delay, and can converge to the optimal or near-optimal solution within few iterations, even for the networks environment with uncertain parameters. The incremental rate of computational cost can close to polynomial and is less than exponential rate. The performance measures of the QMRGA are evaluated using simulations. The simulation results show that this approach has fast convergence speed and high reliability. It can meet the real-time requirement in multimedia communication networks.

• Journal of Labour Economics
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• v.32 no.2
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• pp.61-93
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• 2009

In this paper, we estimate the wage premium of English skills in the Korean labor market using Korean Labor and Income Panel Study(KLIPS) data. In a simple OLS model, we find that people with some English skills in terms of self evaluation or job requirement earn 30% more than those who do not have English skills. But in a small sample of relatively young people, higher English lest scores do not raise earnings. When we add SAT scores in the wage equation, there is no wage premium of English skills, and in the IV estimation, we find no "English premium". These results consistently imply that while there is a large wage premium of English skills in the Korean labor market, it reflects unobservable ability for the most part. Meanwhile some of the regression results favor human capital theory over screening theory as an explanation of the nature of the wage premium of English skills.

• The KIPS Transactions:PartD
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• v.18D no.1
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• pp.45-56
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• 2011

The importance of low-power embedded system is being increased. The studies on low-power system have been performed in issues of hardware architecture and operating system. However because the behaviors of software control the working of hardware devices, the power analysis of software is one of critical issues in energy-efficient embedded system development. This paper proposes a technique to extract tasks from software design models with considering power consumption. We first define the criteria for task extraction, and then propose the way to separate out the task from UML 2.0 design models. Our technique can provide the chance to reduce the power consumption as well as to fulfill the performance requirement in the early phase of software development.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.595-599
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• 2002

Edge welding of thin sheets is very difficult because of the fit-up problem and small weld area In laser welding, joint fit-up and penetration are critical for sound weld quality, which can be monitored by appropriate methods. Among the various monitoring systems, visual monitoring method is attractive because various kinds of weld pool information can be extracted directly. In this study, a vision sensor was adopted for the weld pool monitoring in pulsed Nd:YAG laser edge welding to monitor whether the penetration is enough and the joint fit-up is within the requirement. Pulsed Nd:YAG laser provides a series of periodic laser pulses, while the shape and brightness of the weld pool change temporally even in one pulse duration. The shutter-triggered and non-interlaced CCD camera was used to acquire a temporally changed weld pool image at the moment representing the weld status well. The information for quality monitoring can be extracted from the monitored weld pool image by an image processing algorithm. Weld pool image contains not only the information about the joint fit-up, but the penetration. The information about the joint fit-up can be extracted from the weld pool shape, and that about a penetration from the brightness. Weld pool parameters that represent the characteristics of the weld pool were selected based on the geometrical appearance and brightness profile. In order to achieve accurate prediction of the weld penetration, which is nonlinear model, neural network with the selected weld pool parameters was applied.