• Journal of Digital Contents Society
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• v.19 no.2
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• pp.301-307
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• 2018

Generally, search engine summarizes the main contents of the search results so that user can click the site providing the information of the contents to search first. In this study, we demonstrated whether the user clicks on the search results based on the summary content provided by the search engine or on the order of the search result placement through empirical studies through the presentation of search results. By using the API provided by the search engine company, a search site that presents the search results in a regular and inverse order is created, and the click action of each user's search result is displayed in the order of actual click order, click position, and the user's search type such as the route of movement. As a result of the analysis, most users account for more than 60% of users who click on the first and second exposed search results regardless of the search results. It is confirmed that the search priority of users is determined according to the order of search results regardless of the summary of search results.

• Convergence Security Journal
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• v.17 no.5
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• pp.87-92
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• 2017

MANET is a network composed itself because mobile nodes are connected wirelessly. It has been applied to various fields for group communication. However, the dynamic topology by the movement of the nodes causes routing failure frequently because it is difficult to maintain the position information of the nodes participating in the group communication. Also, it has a problem that network performance is decreased due to high overhead for managing information of member nodes. In this paper, we propose a multicast technique using location-based 2-tier virtual group that is flexible and reliable in management of member nodes. The network is composed of cellular zones and the virtual group is constructed using the location information of the nodes in the proposed technique. The virtual group management node is selected to minimize the overhead of location information management for member nodes in the virtual group. In order to improve the reliability for management of member nodes and multicast data transmission, it excludes the gateway node with low transfer rate when setting the route after the packet transmission rate of the member nodes is measured. The excellent performance of the proposed technique can be confirmed through comparative experiments with AMroute method and PAST-DM method.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.3
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• pp.39-47
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• 2002

This paper deals with study of a new framework for the traceback of distributed DoS(Denial of Service) attacks in the Internet, in which many sources flood "spoofed" IP packets towards a single victim. In our scheme, the destination host traces those anonymous packets' losses, and infers the logical end-to-end paths back towards the sources. This method is based on the fact that there is a strong correlation between packet losses when those packets traverse along a same route, and the simulation results show high probabilities of detecting the topology under a certain condition. Compared with previous approaches, our scheme has a number of distinct features: It can be performed in realtime or non-realtime, without any supports of routers or ISPs. Our results may be applied to the inference of physical topology and to support previous approaches.pproaches.

• International Journal of Computer Science & Network Security
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• v.21 no.12
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• pp.137-142
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• 2021

Distance learning universities provide online course content. The main methods of providing class contents are on-demand and live-streaming. This means that students are not restricted by time or space. The advantage is that students can take the course anytime and anywhere. Therefore, unlike commuting students, there is no commuting time to the campus, and there is no natural process required to take classes. However, despite this convenient situation, the attendance rate and graduation rate of distance learning universities tend to be lower than that of commuting universities. Although the course environment is not the only factor, students cannot obtain a bachelor's degree unless they fulfill the graduation requirements. In both commuter and distance learning universities, taking classes is an important factor in earning credits. There are fewer time and space constraints for distance learning students than for commuting students. It is also easy for distance learning students to take classes at their own timing. There should be more ease of learning than for students who commute to school with restrictions. However, it is easier to take a course at a commuter university that conducts face-to-face classes. I thought that the reason for this was that commuting to school was a part of the process of taking classes for commuting students. Commuting to school was thought to increase the willingness and motivation to take classes. Therefore, I thought that the inconvenient constraints might encourage students to take the course. In this research, I focused on the act of commuting to school by students. These situations are also applied to the distance learning environment. The students have physical time constraints. To achieve this goal, I will implement a course restriction method that aims to promote the willingness and attitude of students. Therefore, in this paper, I have implemented a virtual school system called "virtual go to school (VG2S)" that reflects the actual route to school.

• Journal of the Korea Society for Simulation
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• v.19 no.1
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• pp.125-131
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• 2010

In wireless sensor networks application, sensor nodes are randomly deployed in wide and opened environment typically. Since sensor networks have these features, it is vulnerable to physical attacks in which an adversary can capture deployed nodes and use them to inject a fabricated report into the network. This threats of network security deplete the limited energy resource of the entire network using injected fabricated reports. A dynamic en-route filtering scheme is proposed to detect and drop the injected fabricated report. In this scheme, node executes the key redistribution to increases the detection power. It is very important to decide the authentication key redistribution because a frequent key redistribution can cause the much energy consumption of nodes. In this paper, we propose a key redistribution determining method to enhance the energy efficiency and maintain the detection power of network. Each node decides the authentication key redistribution using a fuzzy system in a definite period. The proposed method can provide early detection of fabricated reports, which results in energy-efficiency against the massive fabricated report injection attacks.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.149-155
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• 2009

Attacks in wireless sensor networks (WSN), are similar to the attacks in ad-hoc networks because there are deployed on a wireless environment. However existing security mechanism cannot apply to WSN, because it has limited resource and hostile environment. One of the typical attack in WSN is setting up wrong route that using wormhole. To overcome this threat, Ji-Hoon Yun et al. proposed WODEM (WOrmhole attack DEfense Mechanism) which can detect and counter with wormhole. In this scheme, it can detect and counter with wormhole attacks by comparing hop count and initial TTL (Time To Live) which is pre-defined. The selection of a initial TTL is important since it can provide a tradeoff between detection ability ratio and energy consumption. In this paper, we proposed a fuzzy rule-based system for TTL determination that can conserve energy, while it provides sufficient detection ratio in wormhole attack.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.6
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• pp.1147-1157
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• 2014

Intelligent transportation system (ITS) is realized through a highly ephemeral network, i.e. vehicular ad hoc network (VANET) which is on its way towards the deployment stage, thanks to the advancements in the automobile and communication technologies. However, it has not been successful, at least to date, to install the technology in the mass of vehicles due to security and privacy challenges. Besides, the users of such technology do not want to put their privacy at stake as a result of communication with peer vehicles or with the infrastructure. Therefore serious privacy measures should be taken before bringing this technology to the roads. To date, privacy issues in ephemeral networks in general and in VANET in particular, have been dealt with through various approaches. So far, multiple pseudonymous approach is the most prominent approach. However, recently it has been found out that even multiple pseudonyms cannot protect the privacy of the user and profilation is still possible even if different pseudonym is used with every message. Therefore, another privacy-aware mechanism is essential in vehicular networks. In this paper, we propose a novel identity exchange mechanism to preserve conditional privacy of the users in VANET. Users exchange their pseudonyms with neighbors and then use neighbors' pseudonyms in their own messages. To this end, our proposed scheme conditionally preserves the privacy where the senders of the message can be revoked by the authorities in case of any dispute.

• Fire Science and Engineering
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• v.22 no.3
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• pp.278-286
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• 2008

When big fire in high rise building and multiplex happens, the needs for high prevention system of disaster are being increased for getting the real-time scene state, quick lifesaver, and safe life security. In this paper the proposed evacuation guidance algorithm which analyzed the feature and danger of fire in high rise buildings, gave simplicity and scalability. Our research shows as fire and disaster occur in high rise buildings we construct sensor networks and sense realtime location information on fire alive people, and the situation information for fire instructed quick and safe escaping route by using mesh routing algorithm scheme relative to exit sign.

• Journal of Digital Convergence
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• v.12 no.1
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• pp.423-429
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• 2014

DDoS attacks is upgrade of DoS attacks. Botnet is being used by DDoS attack, so it is able to attack a millions of PCs at one time. DDoS attacks find the root the cause of the attack because it is hard to find sources for it, even after the treatment wavelength serious social problem in this study, the analysis and countermeasures for DDoS attack is presented.

• Journal of the Korea Safety Management & Science
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• v.11 no.4
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• pp.221-228
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• 2009

Electronic Product Code Information Services(EPCIS) is an EPCglobal standard for sharing EPC related information between trading partners. EPCIS provides a new important capability to improve efficiency, security, and visibility in the global supply chain. EPCIS data are classified into two categories, master data (static data) and event data (dynamic data). Master data are static and constant for objects, for example, the name and code of product and the manufacturer, etc. Event data refer to things that happen dynamically with the passing of time, for example, the date of manufacture, the period and the route of circulation, the date of storage in warehouse, etc. There are four kinds of event data which are Object Event data, Aggregation Event data, Quantity Event data, and Transaction Event data. This thesis we propose an event-based data model for EPC Information Service repository in RFID based integrated logistics center. This data model can reduce the data volume and handle well all kinds of entity relationships. From the point of aspect of data quantity, we propose a formula model that can explain how many EPCIS events data are created per one business activity. Using this formula model, we can estimate the size of EPCIS events data of RFID based integrated logistics center for a one day under the assumed scenario.