• Journal of Internet Computing and Services
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• v.15 no.2
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• pp.19-31
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• 2014

In this paper, a parallel backoff delay procedure on multiple IEEE 802.15.4 channels and a channel searching method considering the frequency spectrum of WiFi traffic are studied for IEEE 802.15.4 nodes to avoid the interference from WiFi traffic. In order to search the channels being occupied by WiFi traffic, we analyzed the methods measuring the powers of adjacent channels simultaneously, checking the duration of measured power levels greater than a threshold, and finding the same periodicity of sampled RSSI data as the beacon frame by signal processing. In an wireless channel overlapped with IEEE 802.11 network, the operation of CSMA-CA algorithm for IEEE 802.15.4 nodes is explained. A method to execute a parallel backoff procedure on multiples IEEE 802.15.4 channels by an IEEE 802.15.4 device is proposed with the description of its algorithm. When we analyze the data measured by the experimental system implemented with the proposed method, it is observed that medium access delay times increase at the same time in the associated IEEE 802.15.4 channels that are adjacent each other during the generation of WiFi traffic. A channel evaluation function to decide the interference from other traffic on an IEEE 802.15.4 channel is defined. A channel searching method considering the channel evaluations on the adjacent channels together is proposed in order to search the IEEE 802.15.4 channels interfered by WiFi, and the experimental results show that it correctly finds the channels interfered by WiFi traffic.

• Journal of Internet Computing and Services
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• v.17 no.6
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• pp.81-91
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• 2016

VANET is one of the most developed technologies many people have considered a technology for the next generation. It basically utilizes the wireless technology and it can be used for measuring the speed of the vehicle, the location and even traffic control. With sharing those information, VANET can offer Cooperative ITS which can make a solution for a variety of traffic issues. In this way, safety for drivers, efficiency and mobility can be increased with VANET but data between vehicles or between vehicle and infrastructure are included with private information. Therefore alternatives are necessary to secure privacy. If there is no alternative for privacy, it can not only cause some problems about identification information but also it allows attackers to get location tracking and makes a target. Besides, people's lives or property can be dangerous because of sending wrong information or forgery. In addition to this, it is possible to be information stealing by attacker's impersonation or private information exposure through eavesdropping in communication environment. Therefore, in this paper we propose Privacy Assurance Architecture for VANET to ensure privacy from these threats.

• Journal of Gifted/Talented Education
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• v.23 no.6
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• pp.1019-1034
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• 2013

The purpose of this study is to investigate the characteristics of convergence gifted students through the their perception of the differences about scientists between Science class and Convergence class in gifted science education center. Consequently, this article reports that there are differences in the perception about scientists was distinction between applicants of Convergence and Science class. Science class applicants mainly recognized scientists as pure scientists, but Convergence class applicants recognized scientist were including mathematician, artist, architect, etc. Also Convergence class applicants thought that affective domain including 'effort', 'patience', 'interest' was more important that Science class applicants. On the other hand, when they described the scientists, Science class applicants knew their achievements as scientists more specifically than Convergence class. And to conclude, the characteristics were different between Convergence and Science class applicants in gifted science education center. Based on the result of this study, this paper suggests the following: Firstly, conceptual study is urgent about convergence gifted students in their definition and characteristics. Secondly, information regarding the criteria to select student for convergence class in gifted science education center. Finally, when teaching convergence gifted students, attention should be paid to their characteristics such affective domain.

• Journal of KIISE:Software and Applications
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• v.30 no.11
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• pp.1080-1091
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• 2003

Recently, the distance education has been rapidly proliferated with the rapid growth of the Internet and high speed networks. There has been relatively much research with regard to online lecture (teaching and studying) tools for the distance education, compared to the virtual laboratory tools (for self-study and experiments). In this paper, we design and implement a web-based simulation tool, named as SimDraw, for the virtual laboratory in the distance education. To apply the web-based simulation technology into the distance education, some requirements should be met; firstly, the user interface of the simulation should be very easy for students. Secondly, the simulation should be very portable to be run on various computer systems of remote students. Finally, the simulation program on remote computers should be very thin so that students can easily install the program onto their computers. To meet these requirements, SimDraw adopts the client/server architecture; the client program contains only model development and animation functions so that no installation of a client program onto student's system is required, and it can be implemented by a Java applet in Web browsers. The server program supports client programs by offering the functions such as remote compiling, model storing, library management, and user management. For the evaluation of SimDraw, we show the simulation process using the example experimentation of the RIP(Routing Information Protocol) Internet routing protocol.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3389-3404
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• 2012

Based on the case study methods, the study analyzes emergence and ensuing typology of global ebook platforms such as Google eBook, Amazon Kindle, iBooks Store. Global ebook platforms show adaptation process responding to rapidly changing digital technological envirment and it's fitness landscape. The critical elements in its emerging process are the distinct selection criteria, the degree of resource abundance and the search process based on open innovation. Based on these critical elements, the global platforms show speciation process, so called niche creation and are evolving into a variety of the typology based on the initial condition of key resource which makes the platform emerge and grow. Each global ebook platforms is evolving into open platform, hybrid platform, closed platform. Google eBook has openness and extensibility due to a variety of devices based on Android and a direct involvement of actors. Amazon Kindle has developed from a online bookstore and into the hybrid platform which have not only closed quality but also openness with ebook devices and mobile network. iBooks Store has developed into the closed platform through the agency model based on competitive hardwares and closed quality with iphone and ipad.

• Journal of KIISE
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• v.42 no.8
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• pp.1057-1064
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• 2015

The tactical network is system based on wireless networking technologies that ties together surveillance reconnaissance systems, precision strike systems and command and control systems. Several alternative paths exist in the network because it is connected as a grid to improve its survivability. In addition, the network topology changes frequently as forces and combatants change their network access points while conducting operations. However, most Internet routing standards have been designed for use in stable backbone networks. Therefore, tactical networks may exhibit a deterioration in performance when these standards are implemented. In this paper, we propose Priority based Multi-Path routing with Local Optimization(PMPLO) for a tactical backbone network. The PMPLO separately manages the global and local metrics. The global metric propagates to other routers through the use of a routing protocol, and it is used for a multi-path configuration that is guaranteed to be loop free. The local metric reflects the link utilization that is used to find an alternate path when congestion occurs, and it is managed internally only within each router. It also produces traffic that has a high priority privilege when choosing the optimal path. Finally, we conducted a simulation to verify that the PMPLO can effectively distribute the user traffic among available routers.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2641-2654
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• 2014

In the smart media environment, magazine industry has been experiencing a transition to ecosystem of value network, which includes high complexity and ambiguity. Using case study method, this article conducts research on digital convergence, the model of magazine ecosystem and adaptation strategy of global magazine companies. Research findings have it that the way of contents production of global magazines has been based on collaborative production system within communities, expert communities, creative users, media contents companies and magazine platform. The system shows different patterns and characteristics depending on magazine-driven platform, Platform-driven platform or user-driven platform. Collaboration system has been confirmed in various cases: Huffington Post and Zinio which collaborate with media contents companies, Amazon magazines and Bookish with magazine companies, Huffington Post and Wired with expert communities, and Flipboard with creative users and communities. Foreign magazine contents diverge into (paper, electronic, app and web magazine) as they start the lively trades of their contents on the magazine platform. In the area of contents uses, readers employ smart media technology effectively such as cloud computing, artificial intelligence and module individualization, making it possible for the virtuous cycle to remain in the relationship within communities, expert communities and creative users.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3074-3078
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• 2014

We implemented a dual-band slot-coupled patch (SCP) antenna for the external access point (AP) of the wireless local area network (WLAN) band. The antennas consist of two radiators on three layers. The first radiator is a slotted bow tie antenna operating at the 2.4-2.483 GHz band. The second radiator is a patch antenna with parasitic elements operating at 4.095-5.845 GHz. The high gain and broad bandwidth is important element of wireless access. To enhance the bandwidth, a coupled feeding was used in the first radiator and a parasitic patch was used in the second radiator. We used a parasitic patch and chock to improve the directivity and isolation in both radiators. The porposed antenna was designed by EM simulation tool and measured. The S11 of the antenna was less than -11dB (VSWR 1.8:1) at operating frequency. The peak gain was more than 6 dBi in the first antenna and more than 8 dBi in the second antenna.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.732-742
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• 2016

This study suggests methods of defense against low-level high-bandwidth DDoS attacks by adding a solution with a time limit factor (TLF) to an existing high-bandwidth DDoS defense system. Low-level DDoS attacks cause faults to the service requests of normal users by acting as a normal service connection and continuously positioning the connected session. Considering this, the proposed method makes it possible for users to show a down-related session by considering it as a low-level DDoS attack if the abnormal flow is detected after checking the amount of traffic. However, the service might be blocked when misjudging a low-level DDoS attack in the case of a communication fault resulting from a network fault, even with a normal connection status. Thus, we made it possible to reaccess the related information through a certain period of blocking instead of a drop through blacklist. In a test of the system, it was unable to block the session because it recognized sessions that are simply connected with a low-level DDoS attack as a normal communication.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.310-318
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• 2016

This study examined the correlation between microscopic factors and pedestrian volume in an urban environment, focusing on the microscopic factors that stimulate the pedestrian volume, such as density, diversity, network structure, accessibility, and the form of lots and buildings. In particular, factors already known to boost the pedestrian volume include density, diversity and accessibility, which are three variables strongly related to the concept of the 3Ds (Density, Diversity, Design) proposed by Cervero and Kockelman (1997) and the additional 2Ds (Distance to Transit, Destination Accessibility) suggested by Ewing et al. (2008). The analysis in this study was based on the 2010 survey of the floating population in Seoul, particularly on the data from Jongro-gu and Jung-gu in Gangbuk area. Data were established by analyzing the microscopic factors within a 500m radius around each of the 1,028 spots from which the pedestrian volume in Jongro-gu and Jung-gu was measured. The analysis showed that density, diversity and accessibility, three factors that were already known to be effective in increasing pedestrian volume, also have the same effect in Jongro-gu and Jung-gu.