• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1262-1269
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• 2003

In structural optimization, static loads are generally utilized although real external forces are dynamic. Dynamic loads have been considered in only small-scale problems. Recently, an algorithm for dynamic response optimization using transformation of dynamic loads into equivalent static loads has been proposed. The transformation is conducted to match the displacement fields from dynamic and static analyses. The algorithm can be applied to large-scale problems. However, the application has been limited to size optimization. The present study applies the algorithm to shape optimization. Because the number of degrees of freedom of finite element models is usually very large in shape optimization, it is difficult to conduct dynamic response optimization with the conventional methods that directly threat dynamic response in the time domain. The optimization process is carried out via interfacing an optimization system and an analysis system for structural dynamics. Various examples are solved to verify the algorithm. The results are compared to the results from static loads. It is found that the algorithm using static loads transformed from dynamic loads based on displacement is valid even for very large-scale problems such as shape optimization.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1363-1370
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• 2003

In structural optimization, static loads are generally utilized although real external forces are dynamic. Dynamic loads have been considered in only small-scale problems. Recently, an algorithm for dynamic response optimization using transformation of dynamic loads into equivalent static loads has been proposed. The transformation is conducted to match the displacement fields from dynamic and static analyses. The algorithm can be applied to large-scale problems. However, the application has been limited to size optimization. The present study applies the algorithm to shape optimization. Because the number of degrees of freedom of finite element models is usually very large in shape optimization, it is difficult to conduct dynamic response optimization with the conventional methods that directly threat dynamic response in the time domain. The optimization process is carried out via interfacing an optimization system and an analysis system for structural dynamics. Various examples are solved to verify the algorithm. The results are compared to the results from static loads. It is found that the algorithm using static loads transformed from dynamic loads based on displacement is valid even for very large-scale problems such as shape optimization.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.135-144
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• 2022

Electromagnetic topology (EMT) technique is a method to analyze each component of the electromagnetic propagation environment and combine them in the form of a network in order to effectively model the complex propagation environment. In a typical commercial communication channel model, since the propagation environment is complex and difficult to predict, a probabilistic propagation channel model that utilizes an average solution, although with low accuracy, is used. However, modeling techniques using EMT technique are considered for application of propagation and coupling analysis of threat electromagnetic waves such as electromagnetic pulses, radio wave models used in electronic warfare, local communication channel models used in 5G and 6G communications that require relatively high accuracy electromagnetic wave propagation characteristics. This paper describes the effective implementation method, algorithm, and program implementation of the electromagnetic topology (EMT) method analyzed in the frequency domain. Also, a method of deriving a response in the time domain to an arbitrary applied signal source with respect to the EMT analysis result in the frequency domain will be discussed.

• Convergence Security Journal
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• v.17 no.1
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• pp.31-38
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• 2017

As the cyber-attacks through the networks advance, it is difficult for the intrusion detection system based on the simple rules to detect the novel type of attacks such as Advanced Persistent Threat(APT) attack. At present, many types of research have been focused on the application of machine learning techniques to the intrusion detection system in order to detect previously unknown attacks. In the case of using the machine learning techniques, the performance of the intrusion detection system largely depends on the feature set which is used as an input to the system. Generally, more features increase the accuracy of the intrusion detection system whereas they cause a problem when fast responses are required owing to their large elapsed time. In this paper, we present a network intrusion detection system based on artificial neural network, which adopts a multi-objective genetic algorithm to satisfy the both requirements: accuracy, and fast response. The comparison between the proposing approach and previously proposed other approaches is conducted against NSL_KDD data set for the evaluation of the performance of the proposing approach.

• Journal of the Korea Society of Computer and Information
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• v.15 no.9
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• pp.99-107
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• 2010

This paper showed that the integrated system to fortify security was much more efficient than the respective system through the analysis of problems from Firewall and IPS system in the existing security systems. The results of problem analysis revealed that there were the delay of processing time and lack of efficiency in the existing security systems. Accordingly, their performance was evaluated by using the separated Firewall, IPS system, and the integrated system. The result of evaluation shows that the integrated security system this paper suggested is five times faster than the existing one in terms of processing speed of response. This paper demonstrated the excellence of the proposed security system is also more than fivefold in session handling per second and six times process speeding in the CPU processing performance. In addition, several security policies are applied, and it provided a fact that it gave an excellent performance when it comes to protecting from harmful traffic attacks. In conclusion, this paper emphasized that fortifying the integrated security system was more efficient than fortifying the existing one considering in various respects such as cost, management, time, space and so on.

• Convergence Security Journal
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• v.22 no.1
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• pp.93-98
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• 2022

Information service technology continues to develop, and information service continues to expand based on the IT convergence trend. The premeter-based security model chosen by many organizations can increase the effectiveness of security technologies. However, in the premeter-based security model, it is very difficult to deny security threats that occur from within. To solve this problem, a zero trust model has been proposed. The zero trust model requires authentication for user and terminal environments, device security environment verification, and real-time monitoring and control functions. The operating environment of the information service may vary. Information security management should be able to response effectively when security threats occur in various systems at the same time. In this study, we proposed a security policy distribution system in the object reference method that can effectively distribute security policies to many systems. It was confirmed that the object reference type security policy distribution system proposed in this study can support all of the operating environments of the system constituting the information service. Since the policy distribution performance was confirmed to be similar to that of other security systems, it was verified that it was sufficiently effective. However, since this study assumed that the security threat target was predefined, additional research is needed on the identification method of the breach target for each security threat.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.1
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• pp.66-75
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• 2012

The purpose of this study is to analyze the effect of intervention variables which may affect the air travel demand for Jeju domestic flights and to anticipate the air travel demand for Jeju domestic flights. The air travel demand forecasts for Jeju domestic flights are conducted through ARIMA-Intervention Model selecting five intervention variables such as 2002 World Cup games, SARS, novel swine-origin influenza A, Yeonpyeongdo bombardment and Japan big earthquake. The result revealed that the risk factor such as the threat of war that is a negative intervention incident and occurred in Korea has the negative impact on the air travel demand due to the response of risk aversion by users. However, when local natural disasters (earthquakes, etc) occurring in neighboring courtiers and global outbreak of an epidemic gave the negligible impact to Korea, negative intervention incident would have a positive impact on air travel demand as a response to find alternative due to rational expectation of air travel customers. Also we realize that a mega-event such as the 2002 Korea-Japan World Cup games reduced the air travel demand in a short-term period unlike the perception in which it will increase the air travel demand and travel demands in the corresponding area.

• Journal of Distribution Science
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• v.19 no.12
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• pp.91-101
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• 2021

Purpose: This study aims to explore the effects of government's value intervention messages on the prevention and control of infectious disease in the risk communication process in terms of goveremnt policy response to COVID-19 from the mismatch message perspective, and draws the relevant implicaitons. Due to the infeciton spread, some people point out that depression caused by COVID-19 is because of wrong signals of the government and infectious disease prevention and control authorities, namely value intervention messsages. Research design, data and methodology: This study examined the epidcmic situation through message deails regarding the effects of government's mismatch messages on prevention and control of infectious disease and the resulting phenomena. Results: People's lives are under serious threat overall, so the declaration of the end of COVID-19 is almost impossible unlike MERS. Economic downturn due to foreced prevention and control regulaitons of COVID-19, mistruct of social distancing, fatigue on mismatch messages, and moral hazard on the awareness of prevention and control of infectious disease are negative phenomena to risk communiaiton on COVID-19. Conclusions: This study investigated the government authorities' policy sending wrong signals due to mismatching of the reality at this point in time for infectious disease prevention and control from the risk communicaiton perspectrive.

• Asian Journal for Public Opinion Research
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• v.2 no.1
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• pp.52-70
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• 2014

Gathering polling items about China and Japan from 1937 to 2011, we examine how Americans think about these two powerful East Asian countries. Our study investigates American attitudes from two perspectives. First, we analyze the content of polling items asked in the US about China and Japan to track changes in salient issues over a period of over 60 years. Second, by tracking repeated items, we show how American attitudes toward China and Japan have changed over time, both in long-term general favorability, and shorter-term perception of geopolitical, ideological, and economic threat in response to historical events.

• The Journal of the Korea Contents Association
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• v.21 no.1
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• pp.531-540
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• 2021

As cyber attacks and crimes increase exponentially and hacking attacks become more intelligent and advanced, hacking attack methods and routes are evolving unpredictably and in real time. In order to reinforce the enemy's responsiveness, this study aims to propose a method for developing an artificial intelligence-based security control platform by building a next-generation security system using artificial intelligence to respond by self-learning, monitoring abnormal signs and blocking attacks.The artificial intelligence-based security control platform should be developed as the basis for data collection, data analysis, next-generation security system operation, and security system management. Big data base and control system, data collection step through external threat information, data analysis step of pre-processing and formalizing the collected data to perform positive/false detection and abnormal behavior analysis through deep learning-based algorithm, and analyzed data Through the operation of a security system of prevention, control, response, analysis, and organic circulation structure, the next generation security system to increase the scope and speed of handling new threats and to reinforce the identification of normal and abnormal behaviors, and management of the security threat response system, Harmful IP management, detection policy management, security business legal system management. Through this, we are trying to find a way to comprehensively analyze vast amounts of data and to respond preemptively in a short time.