• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.27 no.3
• /
• pp.579-589
• /
• 2017

The cloud environment is hypervisor-based, and many virtual machines are interconnected, which makes propagation of malicious code easier than other environments. Accordingly, this paper proposes a malicious traffic dynamic analysis system for secure cloud environment. The proposed system continuously monitors and analyzes malicious activity in an isolated virtual network environment by distinguishing malicious traffic that occurs in a cloud environment. In addition, the analyzed results are reflected in the distinguishment and analysis of malicious traffic that occurs in the future. The goal of this research is secure and efficient malicious traffic dynamic analysis by constructing the malicious traffic analysis environment in the cloud environment for detecting and responding to the new and variant malicious traffic generated in the cloud environment.

• Journal of Communications and Networks
• /
• v.10 no.4
• /
• pp.422-429
• /
• 2008

Mobile peer-to-peer (P2P) systems have recently got in the limelight of the research community that is striving to build efficient and effective mobile content addressable networks. Along this line of research, we propose a new peer-to-peer file sharing protocol suited to mobile ad hoc networks (MANET). The main ingredients of our protocol are network coding and mobility assisted data propagation, i.e., single-hop communication. We argue that network coding in combination with single-hop communication allows P2P file sharing systems in MANET to operate in a more efficient manner and helps the systems to deal with typical MANET issues such as dynamic topology and intermittent connectivity as well as various other issues that have been disregarded in previous MANET P2P researches such as addressing, node/user density, non-cooperativeness, and unreliable channel. Via simulation, we show that our P2P protocol based on network coding and single-hop communication allows shorter file downloading delays compared to an existing MANET P2P protocol.

• The KIPS Transactions:PartC
• /
• v.12C no.3 s.99
• /
• pp.361-368
• /
• 2005

Internet mail has become a common communication method around the world because of tremendous Internet service usage increment. In other respect, Most Internet users' mail addresses are exposed to spammer, and the damage of Junk mail is growing bigger and bigger. These days, Junk mail delivery problem is becoming more serious, because this is used for an attack or propagation scheme of malicious code. It's a most dangerous dominant cause for computer system accident. This paper shows the Junk mail filtering model and implementation which is based on FQDN (Fully Qualified Domain Name) check and evaluates it for proposing advanced scheme against Junk mail.

• Journal of the Korean Society of Combustion
• /
• v.16 no.2
• /
• pp.23-32
• /
• 2011

To investigate cell formation in hydrocarbon/hydrogen/carbon monoxide-air premixed flames, the outward propagation and cellular instabilities were experimentally studied in a constant pressure combustion chamber at room temperature and elevated pressures. Unstretched laminar burning velocities and Markstein lengths of the mixtures were obtained by analyzing high-speed schlieren images. In this study, hydrodynamic and diffusional- thermal instabilities were evaluated to examine their effects on flame instabilities. The experimentally-measured unstretched laminar burning velocities were compared to numerical predictions using the PREMIX code. Effective Lewis numbers of premixed flames with methane addition decreased for all of the cases; meanwhile, effective Lewis numbers with propane addition increased for lean and stoichiometric conditions and increased for rich and stoichiometric cases for hydrogen-enriched flames. With the addition of propane, the propensity for cell formation significantly was diminished, whereas cellular instabilities for hydrogen-enriched flames were promoted. However, similar behavior of cellularity was obtained with the addition of methane to the reactant mixtures.

• IE interfaces
• /
• v.20 no.2
• /
• pp.216-226
• /
• 2007

In code-division multiple-access (CDMA) systems with soft handoff, mobile station (MS) within soft handoff region can use multiple radio channels and receive their signals from multiple base stations (BSs) simultaneously. In this paper, the effects of soft handoff region ratio (SHRR) on reverse link of a CDMA cellular system are analytically investigated. In order to analyze the network performance and quality of service (QoS) perceived by users more realistically, both the soft capacity increasing factor and the traffic load variation affected by SHRR are jointly considered and a two-dimensional continuous time Markov chain (CTMC) model is built. In the numerical example, it is observed that the optimal guard channel exists according the variations of the traffic load and propagation conditions when the proper value of SHRR is determined.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 1997.11a
• /
• pp.305-310
• /
• 1997

There are many parameters in prediction of forest fire spread. The variables such as fuel moisture, fuel loading, wind velocity, wind direction, relative humidity, slope, and solar aspect have important effects on fire. Particularly, wind and slope factors are considered to be the most important parameters in propagation of forest fire. Generally, slope effect cause different wind distribution in mountain area. However, this effect is disregarded in complex geometry. In this paper, wind is estimated by applying computational fluid dynamics to the forest geometry. Wind velocity data is obtained by using CFD code with Newtonian model and slope is calculated with geometrical data. These data are applied fer 2-dimentional forest fire spreading algorithm with Korean ROS(Rate Of Spread). Finally, the comparison between the simulation and the real forest fire is made. The algorithm spread of forest fire will help fire fighter to get the basic data far fire suppression and the prediction to behavior of forest fire.

• Fire Science and Engineering
• /
• v.8 no.1
• /
• pp.9-20
• /
• 1994

To understand the phenomena of laminar diffusion flame along vortical walt, the numerical analysis has been performed. Keller-box method was used to solve the problem in the boundary layer. The governing equation is simplified by thin-flame approxiamtion. And energy and chemical species equations are normalized with Schvab-Zeldovich variables. A physical domain is divided the boundary layer along streamwise coordinate as the combustion region and the propagation region. And Radiation model is concerned in these region. As a result, typical phenomena have been observed. Comparison of the numerical results with experimental data shows that the present method can successfully predict phenomena of laminar diffusion flame along upright surface.

• Journal of the Optical Society of Korea
• /
• v.17 no.4
• /
• pp.328-335
• /
• 2013

Due to the rapid advancement of auto-refractor technology, most optometry shops provide refraction services. Despite their speed and convenience, the measurement values provided by auto-refractors include a significant degree of error due to psychological and physical factors. Therefore, there is a need for repetitive testing to obtain a smaller mean error value. However, even repetitive testing itself might not be sufficient to ensure accurate measurements. Therefore, research on a method of measurement that can complement auto-refractor measurements and provide confirmation of refraction results needs to be conducted. The customized optometry model described herein can satisfy the above requirements. With existing technologies, using human eye measurement devices to obtain relevant individual optical feature parameters is no longer difficult, and these parameters allow us to construct an optometry model for individual eyeballs. They also allow us to compute visual images produced from the optometry model using the CODE V macro programming language before recognizing the diffraction effects visual images with the neural network algorithm to obtain the accurate refractive diopter. This study attempts to combine the optometry model with the back-propagation neural network and achieve a double check recognition effect by complementing the auto-refractor. Results show that the accuracy achieved was above 98% and that this application could significantly enhance the service quality of refraction.

• Nuclear Engineering and Technology
• /
• v.53 no.9
• /
• pp.2816-2829
• /
• 2021

Decay heat residuals of spent nuclear fuel (SNF), i.e., the differences between calculations and measurements, were obtained previously for various spent fuel assemblies (SFA) using the Polaris module of the SCALE code system. In this paper, we compare decay heat residuals to their uncertainties, focusing on four PWRs and four BWRs. Uncertainties in nuclear data and model inputs are propagated stochastically through calculations using the SCALE/Sampler super-sequence. Total uncertainties could not explain the residuals of two SFAs measured at GE-Morris. The combined z-scores for all SFAs measured at the Clab facility could explain the resulting deviations. Nuclear-data-related uncertainties contribute more in the high burnup SFAs. Design and operational uncertainties tend to contribute more to the total uncertainties. Assembly burnup is a relevant variable as it correlates significantly with the SNF decay heat. Additionally, burnup uncertainty is a major contributor to decay heat uncertainty, and assumptions relating to these uncertainties are crucial. Propagation of nuclear data and design and operational uncertainties shows that the analyzed assemblies respond similarly with high correlation. The calculated decay heats are highly correlated in the PWRs and BWRs, whereas lower correlations were observed between decay heats of SFAs that differ in their burnups.

• Acta Via Serica
• /
• v.4 no.1
• /
• pp.125-146
• /
• 2019

This paper deals with the question of the origin of polo. Although it is a sport that has been mainly active in the West since the nineteenthcentury, it is well known that British troops in the northern part of Pakistan learned about the sport from the local people there. Most agree that the origin of polo is Iran. However, in this paper, rather than specifying a specific area as the birthplace of polo, it is argued that polo was a cultural phenomenon commonly found on the Silk Road. This is based on the fact that polo has been known for centuries in China, the Korean Peninsula, and Japan, as well as throughout Iran, northern India, Tibet, Central Asia, and the Uighur Autonomous Region. Yet, the transmission of polo cannot be traced chronologically according to the supposed propagation route. This cultural phenomenon has changed over a long period of time according to the local environment, and the change was caused by mutual exchanges, not by one party. Therefore, there are limitations to interpreting cultural phenomena linearly. Thus, the origin of polo could also be identified with another area, namely Baltistan in modern day Pakistan, instead of Iran. These results support the argument that to understand Silk Road civilization, a process-centric approach based on 'exchanges', not a method of exploring archetypes to find 'the place of origin', should be utilized. Polo is undoubtedly an important cultural artifact with which to read the Silk Road as a cultural belt complex, as well as an example of the common culture created by the whole Silk Road.