• Proceedings of the Korean Information Science Society Conference
• /
• 2002.10e
• /
• pp.160-162
• /
• 2002

분산 가상 환경(Distributed Virtual Environment, DVE)시스템의 규모가 커지면서 확장성(scalability)이 중요한 이슈가 되고 있다. 시스템의 확장성을 높이기 위해 제안된 다중 서버 DVE 시스템에서 사용자들의 집단적인 움직임 특성은 서버간 작업부하의 불균형을 초래한다. 이는 전체 시스템의 효용을 떨어뜨리고 다중 서버의 효과를 감소시킨다. 결과적으로 시스템의 확장성이 저하된다. 이러한 문제를 해결하기 위해 기존에 제안된 로드 밸런싱 기법은 크게 로컬 기법과 글로벌 기법으로 구분할 수 있다. 로컬 기법은 적은 비용을 갖지만 작업부하의 분포가 한쪽으로 치우쳐 있을 경우 성능이 낮다. 글로벌 기법은 좋은 성능을 보여주는 반면, 서버의 수가 증가하면 비용이 크게 증가한다. 본 논문은 서버들의 작업부하분포에 동적으로 적응(adaptation)하는, 대규모 다중 서버 DVE 시스템을 위한 확장성 있는 로드 밸런싱 기법을 제안한다. 제안하는 기법에서 과부하된 서버는 그 주변 서버들의 작업부하가 적을 경우 로컬 확산 (Local Diffusion) 로드 밸런싱을 수행하고, 그렇지 않을 경우 제한적 글로벌 (Limited Scope Global)로드 밸런싱을 수행한다. 시뮬레이션 결과를 통해 제안하는 기법이 효율(efficiency)의 측면에서 기존의 로컬 기법과 글로벌 기법보다 각각 14%, 3%가 우수함을 보인다. 또한, 제안하는 기법은 서버의 수가 증가함에 따라 효율이 감소하는 추세가 기존 기법들보다 완만함을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.5 no.11
• /
• pp.1997-2015
• /
• 2011

In this paper, we propose the enhanced network-based mobility management protocol, called enhanced proxy mobile ipv6 (E-PMIPv6), which can provide mobile nodes (MNs) with a fast and efficient mobility service in PMIPv6 domain. The proposed scheme can provide a fast and efficient mobility service to MNs and also the strength of network scalability and stability to an access network by proposing the dynamic virtual hierarchical network architecture. In addition, the pre-authentication procedure for an MN, based on the information of neighbor mobile access gateway (MAG) list in the enhanced-policy server (E-PS), is proposed to support seamless handover by reducing MN's handover latency. Through performance evaluations of numerical analyses and simulations, we have confirmed and verified the superiority of the proposed scheme compared to the conventional proxy mobile ipv6 (PMIPv6).

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.14 no.6
• /
• pp.2591-2611
• /
• 2020

Botnets have become one of the most significant threats to Internet-connected smartphones. A botnet is a combination of infected devices communicating through a command server under the control of botmaster for malicious purposes. Nowadays, the number and variety of botnets attacks have increased drastically, especially on the Android platform. Severe network disruptions through massive coordinated attacks result in large financial and ethical losses. The increase in the number of botnet attacks brings the challenges for detection of harmful software. This study proposes a smart framework for mobile botnet detection using static analysis. This technique combines permissions, activities, broadcast receivers, background services, API and uses the machine-learning algorithm to detect mobile botnets applications. The prototype was implemented and used to validate the performance, accuracy, and scalability of the proposed framework by evaluating 3000 android applications. The obtained results show the proposed framework obtained 98.20% accuracy with a low 0.1140 false-positive rate.

• Korean Journal of Computational Design and Engineering
• /
• v.10 no.2
• /
• pp.143-150
• /
• 2005

A design framework to employ the multidisciplinary design optimization technologies on a computer system has been developed and is named as the Extensible Multidisciplinary Design Integration and Optimization System (EMDIOS). The framework can not only effectively solve complex system design problems but also conveniently handle MDO problems. Since the EMDIOS exploits both state-of-the-art of computing capabilities and sophisticated optimization techniques, it can overcome many scalability and complexity problems. It can make users who are not even familiar with the optimization technology use EMDIOS easily to solve their design problems. The client of EMDIOS provides a front end for engineers to communicate the EMDIOS engine and the server controls and manages various resources luck as scheduler, analysis codes, and user interfaces. EMDIOS client supports data monitoring, design problem definition, request for analyses and other user tasks. Three main components of the EMDIOS are the Engineering Design Object Model which is a basic idea to construct EMDIOS, EMDIOS Language (EMDIO-L) which is a script language representing design problems, and visual modeling tools which can help engineers define design problems using graphical user interface. Several example problems are solved and EMDIOS has shown various capabilities such as ease of use, process integration, and optimization monitoring.

• The KIPS Transactions:PartC
• /
• v.10C no.1
• /
• pp.1-10
• /
• 2003

In this paper, we propose a secure communication framework for interaction and information sharing between a server and agents in DS-NVSA(Detection System of Network Vulnerability Scan Attacks) proposed in〔1〕. For the scalability and interoperability with other detection systems, we design the proposed IDMEF and IAP that have been drafted by IDWG. We adapt IDMEF and IAP to the proposed framework and provide SKTLS(Symmetric Key based Transport Layer Security Protocol) for the network environment that cannot afford to support public-key infrastructure. Our framework provides the reusability of heterogeneous intrusion detection systems and enables the scope of intrusion detection to be extended. Also it can be used as a framework for ESM(Enterprise Security Management) system.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.4 no.5
• /
• pp.836-858
• /
• 2010

Web Services allow a user to integrate applications from different platforms and languages. Since mobile applications often run on heterogeneous platforms and conditions, Web Service becomes a popular solution for integrating with server applications. However, because of its verbosity, XML based SOAP messaging gives the possible overhead to the less powerful mobile devices. Based on the mobile client's behavior that it usually exchanges messages with Web Service continuously in a session, we design the Handheld Flexible Representation architecture. Our proposed architecture consists of three main components: optimizing message representation by using a data format language (Simple_DFDL), streaming communication channel to reduce latency and the Context-store to store context information of a session as well as redundant parts of the messages. In this paper, we focus on the Context-store and describe the architecture with the Context-store for improving the performance of mobile Web Service messaging. We verify our approach by conducting various evaluations and investigate the performance and scalability of the proposed architecture. The empirical results show that we save 40% of transit time between a client and a service by reducing the message size. In contrast to solutions for a single problem such as the compression or binarization, our architecture addresses the problem at a system level. Thus, by using the Context-store, we expect reliable recovery from the fault condition and enhancing interoperability as well as improving the messaging performance.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.8
• /
• pp.780-786
• /
• 2012

Surveillance has become one of promising application areas of wireless sensor networks which allow for pervasive monitoring of concerned environmental phenomena by facilitating context awareness through sensor fusion. Existing systems that depend on a postmortem context analysis of sensor data on a centralized server expose several shortcomings, including a single point of failure, wasteful energy consumption due to unnecessary data transfer as well as deficiency of scalability. As an opposite direction, this paper proposes an energy-efficient distributed context-aware surveillance in which sensor nodes in the wireless sensor network collaborate with neighbors in a distributed manner to analyze and aware surrounding context. We design and implement multi-modal sensor stations for use as sensor nodes in our wireless sensor network implementing our distributed context awareness. This paper presents an initial experimental performance result of our proposed system. Results show that multi-modal sensor performance of our sensor station, a key enabling factor for distributed context awareness, is comparable to each independent sensor setting. They also show that its initial performance of context-awareness is satisfactory for a set of introductory surveillance scenarios in the current interim stage of our ongoing research.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.10
• /
• pp.4787-4807
• /
• 2016

Although the dense interconnection datacenter networks (DCNs) (e.g. FatTree) provide multiple paths and high bisection bandwidth for each server pair, the single-path TCP (SPT) and ECMP which are widely used currently neither achieve high bandwidth utilization nor have good load balancing. Due to only one available transmission path, SPT cannot make full use of all available bandwidth, while ECMP's random hashing results in many collisions. In this paper, we present OFPT, an OpenFlow based Parallel Transport framework, which integrates precise routing and scheduling for better load balancing and higher network throughput. By adopting OpenFlow based centralized control mechanism, OFPT computes the optimal path and bandwidth provision for each flow according to the global network view. To guarantee high throughput, OFPT dynamically schedules flows with Seamless Flow Migration Mechanism (SFMM), which can avoid packet loss in flow rerouting. Finally, we test OFPT on Mininet and implement it in a real testbed. The experimental results show that the average network throughput in OFPT is up to 97.5% of bisection bandwidth, which is higher than ECMP by 36%. Besides, OFPT decreases the average flow completion time (AFCT) and achieves better scalability.

• Journal of KIISE:Computer Systems and Theory
• /
• v.28 no.1_2
• /
• pp.80-89
• /
• 2001

The development in the mobile computing systems have arisen new and previously unforeseen problems, such as problems in information management of mobile host, disconnection of mobile host and low bandwidths of wireless communications. Especially, location information management strategy of mobile host results in an increased overhead in mobile computing systems. Due to the mobility of the mobiles host, the changes in the mobile host's address depends on the mobile host's location, and is maintained by mapping physical address on virtual address, Since previously suggested several strategies for mapping method between physical address and virtual address did not tackle the increase of mobile host and distribution of location information, it was not able to support the scalability in mobile computing systems. Thus, to distribute the location inrormation, we propose an advanced n-depth LiST (Location information Search Tree) and the parallel location search and update strategy based on the advanced n-depth LiST. The advanced n-depth LiST is logically a hierarchical structure that clusters the location information server by ring structure and reduces the location information search and update cost by parallel seatch and updated method. The experiment shows that even though the distance of two MHs that communicate with each other is large, due to the strnctural distribution of location information, advanced n-depth LiST results in good performance. Moreover, despite the reduction in the location information search cost, there was no increase in the location information update cost.

• Journal of KIISE:Information Networking
• /
• v.29 no.2
• /
• pp.117-128
• /
• 2002

Virtual LAN (VLAN) is an architecture to enable communication between end stations as if they were on the same LAN regardless of their physical locations. VLAN defines a limited broadcast domain to reduce the bandwidth waste. The Newbridge Inc. developed a layer 3 VLAN product called VIVID, which configures a VLAN based on W subnet addresses. In a VIVID system, a single route server is deployed for address resolution, VLAN configuration, and data broadcasting to a VLAN. If the size of the network, over which the VLANS supported by the VIVID system spans, becomes larger, this single route server could become a bottleneck point of the system performance. One possible approach to cope with this problem is to deploy multiple route servers. We propose two architectures, organic and independent, to expand the original VIVID system to deploy multiple route servers. A course of simulations are done to analyze the performance of each architecture that we propose. The simulation results show that the performances of the proposed architectures depend on the lengths of VLAN broadcasting sessions and the number of broadcast data frames generated by a session. It has also been shown that there are tradeoffs between the scalability of the architecture and their efficiency in data transmissions.