• Journal of Broadcast Engineering
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• v.20 no.1
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• pp.92-109
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• 2015

Broadcast encryption is a cryptographic primitive that allows a sender to securely broadcast a message to a set of receivers. The most influential broadcast encryption system was proposed in 2001 by Naor, Naor, Lotspiech, based on a pseudo-random generator and the Subset Difference (SD) method. In this paper, we suggest a new broadcast encryption system that is based on secret sharing and SD methods. On an efficiency aspect, our system achieves O(r) transmission cost, O($log^2n$) storage cost, and O(1) computational cost for the number n of users and the number r of revoked users. Compared to O(log n) computational cost in the previous SD method, our system has the advantage that it needs only constant-sized computational cost for decryption, regardless of the number n or r. On a security aspect, our system can achieve tighter security reduction than the previous SD method and the gap of security loss is about O(n log n). Moreover, our result shows that it is possible to give the effect of the SD method while using an information-theoretically secure key distribution technique as in the Complete Subtree method.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.8
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• pp.297-306
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• 2018

In this paper, we address how to apply Apache Storm, a distributed stream processing framework, to InfiniBand, a high performance communication device. An easy way to run Storm on InfiniBand is to simply use IPoIP (IP over InfiniBand). However, this method causes a serious CPU load on the node, which is caused by frequent context switches and buffer copies. To solve this problem, we propose a new communication method using InfiniBand's Remote Direct Memory Access (RDMA) function in Storm. First, we design and implement RJ-Netty (RDMA/JXIO Netty), a new framework that replaces Netty, the legacy framework, to exploit RDMA functionality. Second, we reimplement the related classes so that Storm can use both existing Netty and new RJ-Netty. Third, we extend the JXIO server functionality so as to support multi-threading to maximize the performance of RJ-Netty. Experimental results show that the proposed RJ-Netty significantly reduces CPU load while improving message throughput compared to IPoIB as well as Ethernet. This paper is the first attempt to run Apache Storm on InfiniBand, and we believe that it is an excellent research result that improves the performance of Storm by using InfiniBand RDMA.

• The KIPS Transactions:PartC
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• v.17C no.4
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• pp.307-314
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• 2010

Recently, it is proved that contactless smart-card based RFID tags, which is used for proximity authentication, are vulnerable to relay attacks with various location-based attacks such as distance fraud, mafia fraud and terrorist fraud attacks. Moreover, distance bounding protocols have been researched to prevent these relay attacks that can measure the message transmitted round-trip time between the reader and the tag. In 2005, Hancke and Kuhn first proposed an RFID distance bounding protocol based on secure hash function. However, the Hancke-Kuhn protocol cannot completely prevent the relay attacks because an adversary has (3/4)$^n$ attack success probability. Thus, this paper proposes a new distance-bounding protocol for light-weight RFID systems that can reduce to (5/8)$^n$ for the adversary's attack success probability. As a result, the proposed protocol not only can provide high-space efficient based on a secure hash function and XOR operation, but also can provide strong security against the relay attacks because the adversary's attack success probability is optimized to (5/8)$^n$.

• Journal of Fashion Business
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• v.7 no.1
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• pp.38-54
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• 2003

This study looked into the present status of e-mail marketing, which is conducted in local Internet fashion shopping malls and is being used as a one-to-one marketing method in the e-CRM concept so as to establish an effective e-mail marketing policy by grasping problems based on the current status and by presenting solutions to the problems. This study analyzed the e-mail letters received during a certain period of time by 30 professional Internet fashion shopping malls of with famous goods, brands and non-brands. Four individuals subscribed to shopping mall through the procedure for membership applying for e-mail services. The analysis showed that there were no shopping malls that were doing a differentiated e-mail marketing among Internet shopping malls. As for time factor, they were sending e-mail letters irregularly regardless of a certain cycle. And as for visual factor, they didnt have any standard for the content of the mail. As for content factor, the contents of their mail were not differentiated and all the same. The comparison of fashion malls showed that the brand shopping malls were the most active in e-mail marketing. On the basis of the problems, the direction for the effective e-mail marketing of Internet shopping malls are presented as follows: First, individualized contents fitting for customers should be developed, and differentiated mailing services should be provided thereby. Second, each shopping mall should make periodic tests of mailing to find out the optimal time and day to provide e-mail services to the customers at the designated time. Third, e-mail should be differentiated fitting for the website according to a certain on a certain standard for visual effects and the identity of shopping mall should be established. Firth, in the contents of e-mail, the image and message elements should be properly harmonized and creative policies should be made with interactive or recreational elements. Fifth, a homepage policy which can satisfy customers demand for information when the e-mail is clicked on..

• Journal of KIISE
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• v.41 no.10
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• pp.810-823
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• 2014

The wireless mesh network based on IEEE 802.11s provides a routing based on a destination address as it inherits legacy internet architecture. However, this architecture interested in not 'what' which is originally the users goal but 'where'. Futhermore, because of the rapid increase of the number of mobile devices recently, the mobile traffic increases geometrically. It reduces the network effectiveness as increasing many packets which have same payload in the situation of many users access to the same contents. In this paper, we propose an OpenFlow-based contents routing for the wireless mesh network(WMN) to solve this problem. We implement contents layer to the legacy network layer which mesh network uses and the routing technique based on contents identifier for efficient contents routing. In addition we provide flexibility as we use OpenFlow. By using this, we implement caching technique to improve effectiveness of network as decreasing the packet which has same payload in WSN. We measure the network usage to compare the flooding technique, we measure the delay to compare environment using caching and non caching. As a result of delay measure it shows 20% of performance improve, and controller message decrease maximum 89%.

• The KIPS Transactions:PartD
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• v.10D no.4
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• pp.591-602
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• 2003

Delay and discontinuance phenomenon of service are cause by sudden increase of the network communication amount and the quantity consumed of resources when Internet users are driven excessively to a conventional single large database sewer. To solve these problems, spatial database cluster consisted of several single nodes on high-speed network to offer high-performance is risen. But, research about spatial join operation that can reduce the performance of whole system in case process at single node is not achieved. So, in this paper, we propose efficient parallel spatial join processing method in a spatial database cluster system that uses data partitions and replications method that considers the characteristics of space data. Since proposed method does not need the creation step and the assignment step of tasks, and does not occur additional message transmission between cluster nodes that appear in existent parallel spatial join method, it shows performance improvement of 23% than the conventional parallel R-tree spatial join for a shared-nothing architecture about expensive spatial join queries. Also, It can minimize the response time to user because it removes redundant refinement operation at each cluster node.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.9
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• pp.369-380
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• 2013

Recently, role-based distributed system models have been proposed to support adaptive interactions in ubiquitous application environment. A Role-based distributed model regards an application as an organization composed of roles, and separate players running role processes from the roles. When an application is running, it binds a role with a player, and the player runs dynamically assigned role processes provided by an application for supporting adaptability. However, there has not been much attention on researches about development and runtime environment for role-based distributed systems. In this paper we suggest an application framework as an environment for developing and executing role-base distributed systems. The application framework is divided into two parts: an organization framework to manage and construct an organization composed of roles necessary in the application, and a player framework to provide running environment for players. In this paper, we focus on the organization framework which supports the creation and management of organizations, directory service for players and allocation of players to roles, and message brokering between roles and players. The proposed framework makes developers to be able to develop highly adaptive distributed systems in the ubiquitous environment.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.4
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• pp.369-380
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• 2003

With the proliferation of a wireless support and the advances of mobile devices, there is a growing need of making it available for a wireless network as well. Low bandwidth of a wireless network is one of the major issues that should be considered for extending a synchronous collaboration system developed for a wired network to supuort a wireless network. We propose a priority-based view synchronization scheme, exploiting the relaxed synchronization. The proposed scheme leverages the fact that mobile users need not have the exactly same view as the users in a wired network since they usually have a limited screen size and thus focus only on part of a whole document. We evaluate the performance of a simple group editor with the propose scheme using ns -2. The performance results show that the proposed scheme keeps the message transmission delay low so that mobile users can have synchronous colloboration with wired users without signification delay. The proposed scheme is designed and implemented as a framework to support various kinds of realtime groupware applications, exploiting the existing groupware framework, Habanero. As a client program, we implemented a simple group text editor.

• Journal of KIISE
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• v.43 no.11
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• pp.1233-1244
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• 2016

In the IoT network environments for LLNs(Low power and Lossy networks), IPv6 Routing Protocol for Low Power and Lossy networks(RPL) has been proposed by IETF(Internet Engineering Task Force). The goal of RPL is to create a directed acyclic graph, without loops. As recommended by the IETF standard, RPL route recovery mechanisms in the event of a failure of a node should avoid loop, loop detection, DIO Poisoning. In this process, route recovery time and control message might be increased in the sub-tree because of the repeated route search. In this paper, we suggested RPL route recovery method to solve the routing overhead problem in the sub-tree during a loss of a link in the RPL routing protocol based on IoT wireless networks. The proposed method improved local repair process by utilizing a route that could not be selected as the preferred existing parents. This reduced the traffic control packet, especially in the disconnected node's sub tree. It also resulted in a quick recovery. Our simulation results showed that the proposed RPL local repair reduced the recovery time and the traffic of control packets of RPL. According to our experiment results, the proposed method improved the recovery performance of RPL.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.23
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• pp.10157-10164
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• 2015

Background: Breast cancer is the most common cancer among women in the State of Qatar. Due to low participation in breast cancer screening (BCS) activities, women in Qatar are often diagnosed with breast cancer at advanced stages of the disease. Findings indicate that low participation rates in BCS activities are significantly related to women's low level of awareness of breast cancer screening. The objectives of this study were to: (1) determine the factors that influence Qatari women's awareness of breast cancer and its screening activities: and (2) to find ways to effectively promote breast cancer screening activities among Arabic speaking women in Qatar. Materials and Methods: A multicenter, cross-sectional quantitative survey of 1,063 (87.5% response rate) female Qatari citizens and non-Qatari Arabic-speaking residents, 35 years of age or older, was conducted in Qatar from March 2011 to July 2011. Outcome measures included participant awareness levels of the most recent national recommended guidelines of BCS, participation rates in BCS activities, and factors related to awareness of BCS activities. Results: While most participants (90.7%) were aware of breast cancer, less than half had awareness of BCS practices (28.9% were aware of breast self-examination and 41.8% of clinical breast exams, while 26.4% knew that mammography was recommended by national screening guidelines. Only 7.6% had knowledge of all three BCS activities). Regarding BCS practice, less than one-third practiced BCS appropriately (13.9% of participants performed breast self-examination (BSE) monthly, 31.3% had a clinical breast exam (CBE) once a year or once every two years, and 26.9% of women 40 years of age or older had a mammogram once every year or two years). Awareness of BCS was significantly related to BCS practice, education level, and receipt of information about breast cancer and/or BCS from a variety of sources, particularly doctors and the media. Conclusions: The low levels of participation rates in BCS among Arab women in this study indicate a strong need to increase awareness of the importance of breast cancer screening in Qatari women. Without this awareness, compliance with the most recent breast cancer screening recommendations in Qatar will remain low. An increased effort to implement mass media and public health campaigns regarding the impact of breast cancer on women's health and the benefits of early detection of breast cancer must be coupled with an enhanced participation of health care providers in delivering this message to Qatar population.