• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.816-822
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• 2013

In modern networks, data rate is getting faster and transferred data is extremely increased. At this point, the malicious codes are evolving to various types very fast, and the frequency of occurring new malicious code is very short. So, it is hard to collect/analyze data using general networks with the techniques like traditional intrusion detection or anormaly detection. In this paper, we collect and analyze the data more effectively with cloud environment than general simple networks. Also we analyze the malicious code which is similar to real network's malware, using botnet server/client includes DNS Spoofing attack.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.9
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• pp.223-228
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• 2016

Nowadays users of Virtual Environment are want to play with thousands of players in an evolving virtual world at the same time over the internet. So, the load of this kind of Virtual Environments is heavier than that of any other precedents. One of load balancing methods is map-partition to divide the load of entire system which is vulnerable to delay message between clients and servers. In this paper, we propose a Migration Agent application server architecture using to help migration of player character between field servers and to reduce response time between clients and field servers. Migration Agent is reduce Player Character's responds time as Cache Server, if Player Character move to another Field Server, Player Character need the synchronization process in the DBMS approach, to minimize response time by reducing the period for cross - Player Character Field Server to perform the role. Field Server by placing them in form of a stack existing form of grid, for load concentrated on a specific server.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.415-415
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• 2015

공업지역의 경우 비점오염원의 유출원단위가 타 토지이용보다 높은 것으로 알려져 있고, 불투수면의 비율이 높아 강우 초기에 오염물질이 다량으로 유출되는 특성을 가지고 있다. 공업지역의 비점오염원 유출 특성을 파악하고 저감 대책을 수립하기 위해서는 강우 유출수에 대한 장기적인 모니터링이 필요하다. 본 연구의 목적은 공업지역을 대상으로 강우 발생에 따른 유출량 및 수질을 조사하여 비점오염원의 배출 특성을 분석하는데 있다. 본 연구의 대상지역은 경기도 성남시 중원구 상대원동의 위치한 공업지역 3지점으로 선정하였다. 비점 유출 조사는 초음파 유량계와 자동채수기를 이용하여 2014년 강우시에 지점별로 7회씩 총 21회를 실시하였다. 유출특성 조사를 위해 집수구역면적, 선행무강우일수, 총강우량, 강우지속시간, 유출지속시간 등의 자료를 수집하여 총유출량과 유출고, 유출률, 강우강도 등을 산정하였다. 강우유출수 샘플링은 국립환경과학원의 '강우 유출수 조사방법'에서 제시한 방법에 따라 실시하였으며, 수질분석 결과를 바탕으로 $BOD_5$, $COD_{Mn}$, TOC, SS, TN, TP 총 6가지 항목에 대한 EMC를 산정하고 강우특성과 연계하여 분석하였다. 모니터링 결과 항목별 EMC 평균(범위)은 $BOD_5$ 2.2 (0.8~5.1) mg/L, $COD_{Mn}$ 4.0 (1.2~8.6) mg/L, TOC 5.4 (1.7~15.7) mg/L, SS 20.9 (2.0~88.9) mg/L, TN 2.4 (0.1~5.8) mg/L, TP 0.2 (0.0~0.9) mg/L로 나타났다. 본 연구의 결과는 공업지역 비점오염 원단위의 정확성을 향상시키는 기초자료로 활용될 수 있을 것이다.

• Journal of Applied Reliability
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• v.18 no.2
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• pp.114-121
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• 2018

Purpose: This study proposes a process for evaluating the preventive maintenance policy for a system with degradation characteristics and for calculating the appropriate preventive maintenance cycle using time- and condition-based maintenance. Methods: First, the collected data is divided into the maintenance history lifetime and degradation lifetime, and analysis datasets are extracted through preprocessing. Particle filter algorithm is used to estimate the degradation lifetime from analysis datasets and prior information is obtained using LSE. The suitability and cost of the existing preventive maintenance policy are each evaluated based on the degradation lifetime and by using a minimum repair block replacement model of time-based maintenance. Results: The process is applied to the degradation of the reverse osmosis (RO) membrane in a seawater reverse osmosis (SWRO) plant to evaluate the existing preventive maintenance policy. Conclusion: This method can be used for facilities or systems that undergo degradation, which can be evaluated in terms of cost and time. The method is expected to be used in decision-making for devising the optimal preventive maintenance policy.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.139-147
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• 2010

A remote user authentication scheme is a two-party protocol whereby an authentication server in a distributed system confirms the identity of a remote individual logging on to the server over an untrusted, open network. In 2005, Liao et al. proposed a remote user authentication scheme using a smart card, in which users can be authenticated anonymously. Recently, Yoon et al. have discovered some security flaws in Liao et al.'s authentication scheme and proposed an improved version of this scheme to fix the security flaws. In this article, we review the improved authentication scheme by Yoon et al. and provide a security analysis on the scheme. Our analysis shows that Yoon et al.'s scheme does not guarantee not only any kind of authentication, either server-to-user authentication or user-to-server authentication but also password security. The contribution of the current work is to demonstrate these by mounting two attacks, a server impersonation attack and a user impersonation attack, and an off-line dictionary attack on Yoon et al.'s scheme. In addition, we propose the enhanced authentication scheme that eliminates the security vulnerabilities of Yoon et al.'s scheme.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.11-25
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• 2019

In Korea, there is a high demand for the operation of differentiated programs in basic research considering the characteristics of academic fields. The results of this study shows that the higher the level of research competence, the higher the quality of research outputs. The results also tell us that the quality level of the research outputs is different according to the field of study. Based on the results, we propose a method to differentiate the selection rate of each discipline in the system that operates the individual basic research projects by the level of research capacity.

• The Journal of the Korea Contents Association
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• v.19 no.3
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• pp.261-274
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• 2019

This paper aims to develop an appropriate methodology for establishing an investment strategy for 'demonstration of artificial rainfall technology using UAV' and that include establishment of a technology classification, set of indicators for technology evaluation, suggestion of final key technology as a whole study area. It is designed to complement the latest research trend analysis results and expert committee opinions using quantitative analysis. The key indicators for technology evaluation consisted of three major items (activity, technology, marketability) and 10 detailed indicators. The AHP questionnaire was conducted to analyze the importance of indicators. As a result, it was analyzed that the attribute of the technology itself is most important, and the order of closeness to the implementation of the core function (centrality), feasibility (feasibility). Among the 16 technology groups, top investment priority groups were analyzed as ground seeding, artificial rainfall verification, spreading and diffusion of seeding material, artificial rainfall numerical modeling, and UAV sensor technology.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.11
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• pp.269-274
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• 2018

MMORPG is a role-playing game that tens of thousands of people access it online at the same time. Users connect to the server through the game client and play with their own characters. If the user moves to a management area of another server beyond the area managed by the server, the user information must be transmitted to the server to be moved. In an actual game, the user is required to synchronize the established and the transferred information. In this paper, we propose a migration agent server in the virtual systems. We implement a seamless virtual server using the grid method to experiment with seamless server architecture for virtual systems. We propose a method to minimize the delay and equalize the load when the user moves to another server region in the virtual environment. Migration Agent acts as a cache server to reduce response time, the response time was reduced by 50% in the case of 70,000 people.

• Smart Media Journal
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• v.8 no.3
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• pp.41-46
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• 2019

In a MMORPG, a typical application of virtual environment systems, it is a common desire to play in a more realistic environment. However, it is very difficult to provide a latency-free virtual environment to a large user base, mainly due to the fact that the real environment must be configured on multiple servers rather than on single server and that data must be shared on the real server when users move from one region to another. Experiencing response delays continuously in the process of information synchronization between servers greatly deteriorates the degree of immersion. In order to solve this problem, it is necessary to minimize the response delay occurring in the information synchronization process between the servers. In this paper, we propose Migration Agent for efficient information synchronization between field servers providing information of virtual environment and minimizing response delay between Field Server and PC(Player Character) and implement it in cloud computing network. In the proposed system, CPU utilization of field server increased by 6 ~ 13%, and response time decreased by 5 ~ 10 seconds over the existing system in 70,000 ~ 90,000 PCs

• Convergence Security Journal
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• v.19 no.2
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• pp.11-19
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• 2019

The blockchain is a technique for managing transaction data in distributed computing manner without the involvement of central trust authority. The blockchain has been used in various area such as manufacturing, culture, and public as well as finance because of its advantage of the security, efficiency and applicability. In the blockchain, it was considered safe against 51% attack because the adversary could not have more than 50% hash power. However, there have been cases caused by large-scale computing attacks such as 51% and selfish mining attack, and the frequency of these attacks is increasing. In addition, since the development of quantum computers can hold exponentially more information than their classical computer, it faces a new type of threat using quantum algorithms. In this paper, we perform the security analysis of blockchain attacks composing the large computing capabilities including quantum computing attacks. Finally, we suggest the technologies and future direction of the blockchain development in order to be safe against large-scale computing attacks.