• The Journal of the Korea Contents Association
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• v.7 no.4
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• pp.83-90
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• 2007

Flow theory has been borrowed from psychology to address positive user experiences with computers and Internet. The flow experience in computer-mediated environment (CME) has been correlated to increased communication, loaming, exploratory behavior and positive affect. A comparative experiment between CME and traditional paper-pencil environment was conducted to verify whether particular environments or interfaces are more conducive to yielding flow among users. The results showed that there were no differences in flow dimensions except 'enjoyment' between CME and paper-pencil environment. But the distorted senses of time among users were significantly different between the media environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.396-413
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• 2017

Dynamically checking the integrity of software at run-time is always a hot and difficult spot for trusted computing. Control-flow integrity is a basic and important safety property of software integrity. Many classic and emerging security attacks who introduce illegal control-flow to applications can cause unpredictable behaviors of computer-based systems. In this paper, we present a software-based approach to checking violation of control flow integrity at run-time. This paper proposes a high-performance and low-overhead software control flow checking solution, control flow checking at virtual edges (CFCVE). CFCVE assigns a unique signature to each basic block and then inserts a virtual vertex into each edge at compile time. This together with insertion of signature updating instructions and checking instructions into corresponding vertexes and virtual vertexes. Control flow faults can be detected by comparing the run-time signature with the saved one at compile time. Our experimental results show that CFCVE incurs only 10.61% performance overhead on average for several C benchmark programs and the average undetected error rate is only 9.29%. Compared with previous techniques, CFCVE has the characteristics of both high fault coverage and low memory and performance overhead.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.6
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• pp.1649-1667
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• 2012

In order to improve the accuracy and universality of the flow metric correlation analysis, this paper firstly analyzes the characteristics of Internet flow metrics as random variables, points out the disadvantages of Pearson Correlation Coefficient which is used to measure the correlation between two flow metrics by current researches. Then a method based on Symmetrical Uncertainty is proposed to measure the correlation between two flow metrics, and is extended to measure the correlation among multi-variables. Meanwhile, the simulation and polynomial fitting method are used to reveal the threshold value between different correlation degrees for SU method. The statistical analysis results on the common flow metrics using several traces show that Symmetrical Uncertainty can not only represent the correct aspects of Pearson Correlation Coefficient, but also make up for its shortcomings, thus achieve the purpose of measuring flow metric correlation quantitatively and accurately. On the other hand, reveal the actual relationship among fourteen common flow metrics.

• Annual Conference of KIPS
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• 2007.11a
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• pp.1061-1064
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• 2007

네트워크의 효율적인 관리를 위해서는 네트워크의 각 호스트에서 발생하는 트래픽을 실시간으로 모니터링 할 수 있는 시스템이 필요하다. 이러한 모니터링의 효율적인 방법 중 하나가 네트워크 장비에서 제공하는 flow 정보를 이용하는 방법이다. 하지만 이는 네트워크 장비의 과부하 발생, 운용비용 상승, 유연성 및 확장성 부족의 단점을 가진다. 이를 극복하기위하여 본 논문에서는 Enterprise 네트워크에 적합한 Flow 기반 실시간 트래픽 모니터링 시스템의 구조를 제안하고, 검증을 위해 구현한 내용을 기술한다. 본 시스템은 패킷을 수집하여 실시간으로 flow 정보를 생성하고 저장하는 Flow Generator 시스템, 저장된 flow 정보를 Analysis 시스템으로 전송하는 Flow Exporter 시스템, Traffic Analysis 시스템, 그리고 분석된 내용을 보여주는 Traffic Reporter 시스템으로 구성된다. 본 시스템은 다양한 분석 목적에 맞게 Flow 정보를 조절할 수 있는 유연성과 다양한 분석시스템을 구축할 수 있는 확장성을 가진다. 본 논문에서 기술한 시스템은 학교 Campus 네트워크를 대상으로 구축되었다.

• The Journal of the Korea Contents Association
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• v.6 no.11
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• pp.95-103
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• 2006

A good storytelling is essential to make a computer game more immersed and appealing as it impress the players emotion. The Storytelling consists of many factors. Among them, the Plot, or the flow of the story (Story-flow) is significant. The 'Call of Duty' is a successful computer game in the aspect of the story-flow. In this paper, the way to apply traditional theories about the story-flow to this game is analyzed. And an applying policy of traditional story-flow theories to computer games is presented.

• Annual Conference of KIPS
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• 2014.11a
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• pp.234-237
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• 2014

This paper provides insights into the sFlow monitoring system of OF@KREONET. OF@KREONET is software defined network (SDN) testbed adapted by KREONET (Korea Research Environment Open NETwork). OF@KREONET uses SDN-based network virtualization to slice the network among multiple concurrent experimenter. Flow Monitoring of OF@KREONET using sFlow. sFlow and OpenFlow can be used to provide an integrated flow monitoring system where OpenFlow controller can be used to define flows to be monitored by sFlow. OF@KREONET flow monitoring system supports monitoring of per slice FlowSpace. An Experimental can monitor his/her own FlowSpace while network administrator can monitor all spaces.

• Journal of applied mathematics & informatics
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• v.15 no.1_2
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• pp.53-75
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• 2004

First, we present two classes of sequential algorithms for minimum flow problem: decreasing path algorithms and preflow algorithms. Then we describe another approach of the minimum flow problem, that consists of applying any maximum flow algorithm in a modified network. In section 5 we present several parallel preflow algorithms that solve the minimum flow problem. Finally, we present an application of the minimum flow problem.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.193-203
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• 2007

In this paper we consider the inverse minimum flow (ImF) problem, where lower and upper bounds for the flow must be changed as little as possible so that a given feasible flow becomes a minimum flow. A linear time and space method to decide if the problem has solution is presented. Strongly and weakly polynomial algorithms for solving the ImF problem are proposed. Some particular cases are studied and a numerical example is given.

• Journal of the Korea Society of Computer and Information
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• v.17 no.2
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• pp.69-76
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• 2012

The purpose of the study is to identify the relationship among the variables related learner's satisfaction, flow experience and self-directedness and verify the path model of causal relationship among those variables in web based computer e-learning. Based on the theoretical rationale, we hypothesized the path model including learner's satisfaction as outcome variable, flow experience and self-directedness as causal and mediating variables. A total of 193 students were participated in this study and the main results showed as follows: 1. Learner's self-directedness showed significant (p<.01), indirect effect on learner's satisfaction mediated by flow experience and the flow experience showed significant (p<.01), direct effect on learner's satisfaction; 2. Among 7 constructs of self-directedness, 'creative approach', 'love of learning', 'self-confidence as a learner' showed significant (p<.01), indirect effects on learner's satisfaction mediated by 'clear goals' construct among flow experience.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.322-323
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• 2017

본 논문은 대규모 트래픽을 처리하는 NFV환경의 서비스 기능 체이닝 영역에서 sFlow 기반의 트래픽 분류기를 이용한 트래픽 관리 기법을 제안하고 있다. sFlow의 실시간 트래픽 샘플링을 사용하여 실시간으로 변화하는 트래픽의 효과적인 관리를 기대할 수 있으며, 제안한 트래픽 관리 기법은 대규모 트래픽의 네트워크 안정성과 보안을 향상시킨다.