• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.10
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• pp.4157-4175
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• 2020

Moving target defense, as a 'game-changing' security technique for network warfare, realizes proactive defense by increasing network dynamics, uncertainty and redundancy. How to select the best countermeasure from the candidate countermeasures to maximize defense payoff becomes one of the core issues. In order to improve the dynamic analysis for existing decision-making, a novel approach of selecting the optimal countermeasure using game theory is proposed. Based on the signal game theory, a multi-stage adversary model for dynamic defense is established. Afterwards, the payoffs of candidate attack-defense strategies are quantified from the viewpoint of attack surface transfer. Then the perfect Bayesian equilibrium is calculated. The inference of attacker type is presented through signal reception and recognition. Finally the countermeasure for selecting optimal defense strategy is designed on the tradeoff between defense cost and benefit for dynamic network. A case study of attack-defense confrontation in small-scale LAN shows that the proposed approach is correct and efficient.

• Information Systems Review
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• v.25 no.4
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• pp.27-45
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• 2023

The importance of information security has grown alongside the development of information and communication technology. However, companies struggle to select suitable countermeasures within their limited budgets. Sönmez and Kılıç (2021) proposed a model using AHP and mixed integer programming to determine the optimal investment combination for mitigating information security breaches. However, their model had limitations: 1) a lack of objective measurement for countermeasure efficacy against security threats, 2) unrealistic scenarios where risk reduction surpassed pre-investment levels, and 3) cost duplication when using a single countermeasure for multiple threats. This paper enhances the model by objectively quantifying countermeasure efficacy using the beta probability distribution. It also resolves unrealistic scenarios and the issue of duplicating investments for a single countermeasure. An empirical analysis was conducted on domestic SMEs to determine investment budgets and risk levels. The improved model outperformed Sönmez and Kılıç's (2021) optimization model. By employing the proposed effectiveness measurement approach, difficulty to evaluate countermeasures can be quantified. Utilizing the improved optimization model allows for deriving an optimal investment portfolio for each countermeasure within a fixed budget, considering information security costs, quantities, and effectiveness. This aids in securing the information security budget and effectively addressing information security threats.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.6
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• pp.815-823
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• 2019

A naval surface-to-air missile is an effective countermeasure against increasing threats of anti-ship missiles. Optimal operation is imperative for high survivability due to limited defense resources of a warship. This paper addresses a problem of optimal engagement to maximize the overall probability of intercept under Shoot-Look-Shoot tactics. The problem is formulated and analyzed with consideration of a realistic single-shoot probability model. The analysis shows that a global solution is achieved for some engagement scenarios. A numerical algorithm to optimize the overall probability of intercept is suggested. An illustrative example is provided to verify our results.

• New & Renewable Energy
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• v.4 no.2
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• pp.31-38
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• 2008

Using a surplus head in presented water supply pipes, we have studied to improve the operating efficiency of small hydro generator, which was chosen for a test model with 00 hydro power plant. With regard to power control and countermeasure of water hammer impact, Finally we have represented the optimal control method through the synthetical analysis of existing system symptoms, operation efficiency, the effect of water hammer impact and system configuration.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.990-996
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• 2005

This paper is countermeasure against the problem point it will be able to occur with infiltration of the hardware and software. And, we proposed the optimum integrated of system construction plan for the SCADA system function set and a system design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.694-698
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• 2006

This paper presents an optimal design process using beads on a body panel to improve interior noise of a passenger vehicle. Except modification of structural members, it is difficult to find effective countermeasures that can work for the intermediate frequency range from 100 Hz to 300 Hz which lies between the booming and low medium frequency. In this study, it is a major goal to find additional counter-measures for this intermediate frequency range by performing optimal design of beads on body panels. The proposed method for design optimization consists of 4 sub-steps, that is, a) problem definition, b) cause analysis, c) countermeasure development and d) validation. The objective function is minimization of interior noise level. The major design variables are the geometrical shape of a bead and combination of beads on the critical panels. Sensitivity analysis and optimization are performed according to the predefined process for an optimal design. It is verified that the proposed design decreases the level of noise transfer function above 5 dB.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.306-320
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• 2021

To ensure safe port operations around the world, it is important to solve mooring problems. In particular, the many ports that face open seas have difficulties with long-period waves. As a countermeasure, the installation of a breakwater is proposed for mooring safety. However, this often cannot be put into practice because of financial issues. Instead, port terminals control berthing schedules with weather forecasting. However, mooring problems remain unsolved, because of inaccurate wave forecasting. To quantify the current situation, numerical simulations are presented with ship motions, fender deflections, and rope tensions. In addition, novel simulations for mooring ropes are proposed considering tension, friction, bending fatigue, and temperature. With this novel simulation, the optimal mooring method in terms of safety and economic efficiency was confirmed. In terms of safety, the optimal mooring method is verified to minimize dangerous mooring situations. Moreover, the optimal mooring method shows economic benefits and efficiency. It can help to reinforce the safety of port terminals and improve the efficiency of port operations.

• Journal of Information Technology Services
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• v.18 no.5
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• pp.155-164
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• 2019

With the emergence of new ICT technologies, information security threats are becoming more advanced, intelligent, and diverse. Even though the awareness of the importance of information security increases, the information security budget is not enough because of the lack of effectiveness measurement of the information security investment. Therefore, it is necessary to optimize the information security investment in each business environment to minimize the cost of operating the information security countermeasures and mitigate the damages occurred from the information security breaches. In this paper, using genetic algorithms we propose an investment optimization model for information security countermeasures with the limited budget. The optimal information security countermeasures were derived based on the actual information security investment status of SMEs. The optimal solution supports the decision on the appropriate investment level for each information security countermeasures.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.1-8
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• 2017

Warpage is a major defect frequently found in the injection molding process, and the reduction of warpage is a very challenging problem because of the uncontrollable factors, such as variations in the process parameters. Without any countermeasure against these noises, attempts to reduce the defects often lead to failure. In this research, a new robust design methodology, based on the Mahalanobis Taguchi System (MTS) to reduce warpage, is presented. The MTS performs the orthogonal array experiments and uses the signal-to-noise (SN) ratio of the Mahalanobis distance as a performance metric. The validity of the proposed method is illustrated through an optimal design of the injection molding process of a CPU base plate.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.173-179
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• 2001

The torsional or axial critical vibration of the order coinciding with the number of propeller blades is simultaneously excited by the harmonic tangential or radial forces acting on the crank shaft and by the harmonic of the same order from the propeller. The exciting torque of propeller is relatively small comparing with that of crank side, but the exciting force of propeller rather larger than that of crank shaft. With this situation, the exciting force of propeller cannot neglect if the axial vibration of propulsion shafting is calculated. With the propeller in its optimal angular position, i.e. its excitation effect opposed to that of the engine, the stresses at the critical revolution will largely cancel themselves out. In this paper, a method of optimizing the angular propeller position with regard to torsional and axial vibration is studied. The optimal relative angle is determined theoretically by calculation results of coupled torsional-axial vibration.