• Journal of Mechanical Science and Technology
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• v.20 no.5
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• pp.652-657
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• 2006

Although many methods about the control of irregular external noise have been introduced and implemented, it is still necessary to design a controller that will be more effective and efficient methods to exclude for various noises. Accumulation of errors due to model tracking, internal noises (thermal noise, shot noise and 1/f noise) that come from elements such as resistor, diode and transistor etc. in the circuit system and numerical errors due to digital process often destabilize the system and reduce the system performance. New stochastic controller is adopted to remove those noises using conventional controller simultaneously. Design method of a model tracking dual controller is proposed to improve the stability of system while removing external and internal noises. In the study, design process of the model tracking dual stochastic controller is introduced that improves system performance and guarantees robustness under irregular internal noises which can be created internally. The model tracking dual stochastic controller utilizing F-P-K stochastic control technique developed earlier is implemented to reveal its performance via simulation.

• Korean Management Science Review
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• v.13 no.3
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• pp.163-172
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• 1996

According to flying hours, aircraft engines require regular overhaul for preventive maintenance. Because of hostile defense environment of Republic of Korea, the aircraft of republic of Korea Air Force(ROKAF) have been operated at the maximum level of availability and have similar overhaul schedule in several months. The concentration of overhaul schedule in a short period demands additional spare engines far exceeding the spare engines for corrective maintenance. If ROKAF decides to purchase extra engines for the preventive maintenance, the extra engines will be used only for the preventive maintenance and will be excess inventory for the most of aircraft life ccle. Also, the procurement of extra engines is significant investment for ROKAF. To help ROKAF schedule the preventive maintenance without significant spending, this study develops a dynamic programming model that is solvable using an integer programming algorithm. The model provides the number of engines that should be overhauled for a month for multiple periods under given constraints. ROKAF actually used this model to solve a T-59 engine overhaul problem and saved about three billion won at one time. ROKAF plans to use this model continuously for T-59 and other weapon systems. Thus, saving for long term will be significant to ROKAF. Finally, with minor modification, this model can be applied to deciding the minimum number of spare engines for preventive maintenance.

• Journal of Drive and Control
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• v.13 no.3
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• pp.1-7
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• 2016

A cold gas blow-down hydraulic actuation system is widely used in missiles that require an actuation system with a fast response time under a limited space with a short operating time and large loads on the actuators. The system consists of a pneumatic part that supplies the regulated high-pressure gas to a reservoir, and a hydraulic part that supplies pressurized hydraulic oil to the actuators by the pressurized gas in the reservoir. This paper proposes a mathematical model to analyze and simulate the pneumatic part of an actuation system that supplies the operating power to the actuators. The mathematical model is based on the ideal gas equation and also considers the models for heat transfer. The model is applied to the pressure vessel and the gas part of the reservoir, and the model for the pneumatic part is established by connecting the two models for the parts. The model is validated through a comparison of the simulation results with the experimental results. The comparison shows that the suggested model could be useful in the design of the pneumatic part of a cold gas blow-down type hydraulic actuation system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3B
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• pp.212-218
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• 2012

An Internet worm is a self-replicating malware program which uses a computer network. As the network connectivity among computers increases, Internet worms have become widespread and are still big threats. There are many approaches to model the propagation of Internet worms such as Code Red, Nimda, and Slammer to get the insight of their behaviors and to devise possible defense methods to suppress worms' propagation activities. The influence of the network characteristics on the worm propagation has usually been modeled by medical epidemic model, named SI model, due to its simplicity and the similarity of propagation patterns. So far, SI model is still dominant and new variations of the SI model, called SI-style models, are being proposed for the modeling of new Internet worms. In this paper, we elaborate the problems of SI-style models and then propose a new accurate stochastic model using an occupancy problem.

• Journal of the Korea Safety Management & Science
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• v.13 no.2
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• pp.51-59
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• 2011

The objective of this study is to develop an evaluation model for the National highway risky areas. Thus, for the purposes of doing this, National highway risky area evaluated targeting to provide determination ranking and suggesting rival-superiority factors as well as under-inferiority factors in ten National highway risky areas. This study developed for modules of risky areas evaluation, using fuzzy set theory and analytic hierarchy process for evaluation model of National highway risky area in transport environment. The preceding studies assess risk analysis through analysis of causal relationships by National highway safety sector not only handles rating scale development suitable for assessment area by referring to accident frequency model but also geometric structures model. As result of this study, this model of Fuzzy Ahp Risk Analysis (FARA) apply for programmable design in real time processing through easily derive strategy for improvement activities to provide a decision-making effectively. Furthermore, this study contributes frame for improvements of National highway construction for renovation's priority strategy as well as future's policy schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.5
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• pp.2732-2753
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• 2019

With the application of wireless sensor networks in the fields of ecological observation, defense military, architecture and urban management etc., the security problem is becoming more and more serious. Characteristics and constraint conditions of wireless sensor networks such as computing power, storage space and battery have brought huge challenges to protection research. Inspired by the danger theory in biological immune system, this paper proposes an intrusion detection model for wireless sensor networks. The model abstracts expressions of antigens and antibodies in wireless sensor networks, defines meanings and functions of danger signals and danger areas, and expounds the process of intrusion detection based on the danger theory. The model realizes the distributed deployment, and there is no need to arrange an instance at each sensor node. In addition, sensor nodes trigger danger signals according to their own environmental information, and do not need to communicate with other nodes, which saves resources. When danger is perceived, the model acquires the global knowledge through node cooperation, and can perform more accurate real-time intrusion detection. In this paper, the performance of the model is analyzed including complexity and efficiency, and experimental results show that the model has good detection performance and reduces energy consumption.

• Journal of Korean Society for Quality Management
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• v.32 no.2
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• pp.212-231
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• 2004

It is very important to produce military goods for customers, and a customer satisfaction index should be developed for quality control of military goods. Seoul National University and Defense Quality Assurance Agency jointly developed MCSI (Military Customer Satisfaction Index). In this paper the model of MCSI is explained, and the sampling design and survey method is introduced. Also a preliminary test was undertaken, and its result is briefly explained.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.298-309
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• 2001

This research aims to unravel the significant features of the human immune system, which would be successfully employed for a novel network intrusion detection model. Several salient features of the human immune system, which detects intruding pathogens, are carefully studied and the possibility and the advantages of adopting these features for network intrusion detection are reviewed and assessed.

• Journal of the military operations research society of Korea
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• v.17 no.1
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• pp.130-145
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• 1991

The literature has recorded many models dealing with manpower forecasting and planning. The approaches used by the various authors are clearly disparate. This paper presents a taxonomy for manpower planning and forecasting methodologies and classifies the landmark developments in this field. The taxonomical schema is then applied to unify the models in consideration of the methods and the decision factors used for forecasting and/or planning. The taxonomy allows for the most complex model structure containing all the factors considered germane in the existing literature.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.2
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• pp.123-127
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• 2007

Through USN field Test Projects launched in 2005, 9 USN application service models such as u-Ocean, u-Construction, u-Farm, u-Hospital has been deployed. We conducted technical, industrial, economical feasibility tests to verify those services. This thesis will cover briefly the current situation of USN industry domestically and internationally. It will show the future prospect of convergence service model based on USN in conjunction with research details and results from previous USN field Test Projects.