• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1457-1467
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• 2015

Depending on the type of Tx-Rx pairs, VHF Data Exchange System (VDES) for maritime communication is expected to employ the different frequency channels. Load imbalance between the different channels turns out to be a critical problem for the multi-hop communication using Ad-hoc Self-Organizing TDMA (ASO-TDMA) MAC protocol, which has been proposed to provide the connectivity between land station and remote ship stations. In order to handle the inter-channel load imbalance problem, we consider a model of the stochastic geomety in this paper. After analyzing the spatial reuse efficiency in each hop region by the given model, we show that the resource utility can be maximized by balancing the inter-channel traffic load with optimal resource allocation in each hop region.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2C
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• pp.132-139
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• 2012

In 2011, Woosik Bae proposed a NLMAP(New Low-cost Mutual Authentication Protocol) in RFID based on hash function. They argued that minimize computation such as random number generation. In addition, NLMAP is safe against replay attack, spoofing attack, traffic analysis and eavesdropping attack due to using mutual authentication. So, when applied to RFID system has advantage such as providing a high level of security at a lower manufacturing cost. However, unlike their argue, attacker can obtain Tag's hash computed unique identification information. This paper proves possible the location tracking and spoofing attack using H(IDt) by attacker. In addition, we propose the improved a mutual authentication protocol in RFID based on hash function and CRC code. Also, our protocol is secure against various attacks and suitable for efficient RFID systems better than NLMAP.

• International Journal of High-Rise Buildings
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• v.6 no.2
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• pp.149-163
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• 2017

With the intensification of urban development in Chinese cities, mixed land use in urban centers extends vertically into 3-D and expands its scale from a single building to commercial clusters. The multi-level pedestrian system in city centers also changed its role from one of traffic isolation to spatial integration, where transit nodes, street sidewalks, squares, building entrances, atriums, and corridors are interconnected, both horizontally and vertically, into a whole spatial system, within which pedestrian flows are guided and shopping facilities are arranged. This paper uses spatial configuration analysis of space syntax to examine the impacts of spatial patterns on movement distribution and the business performance of tenant mix in the multi-level commercial system of the Nanshan Commercial Cultural District in Shenzhen, China. The key objective is to better understand the interactions between the socio-economic variables and spatial design parameters of a shopping complex. The research findings point to the importance of multiplicity between syntactic variables and other spatial variables in influencing the pedestrian flows, business performance and tenant mix in highly complex commercial systems. Particularly noteworthy is the relationship between spatial accessibility measures and the location of escalators, and the ways in which individual commercial buildings are embedded into the overall spatial system. The study suggests that this may lead to the preliminary identification of the spatial qualities of effective vertical extensions of mixed land use in a high-density urban settings.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.187-191
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• 2002

In this paper, We analysed the technical characteristics of a automatic identification system that will introduce in aviation and marine radio stations. IMO's Marine Safety Committee approved revision of chapter V of the Safety of Life at Sea(SOLAS) Convention in 73rd meeting. According to this, AIS will become a mandatory carriage requirement by 01 July 2002. AIS as a surveillance system continuously receives its own position from the GNSS and then repeatedly broadcasts it on a VHF data link for avoiding traffic conflicts and possible disasters. VHF data link is organized so that a specified number of time slots make up a repeatable frame. Each radio station can autonomously allocate and deallocate slots within the frame using selection algorithm which is called SOTDMA(Self-Organized Time Division Multiple Access). The results can be an aid in the continued of understanding technical characteristics for AIS as a broad surveillance system.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.63-71
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• 2009

A car navigation system as an in-vehicle route guidance information (RGI) offers a state-of-the-art technological solution to driver navigation in an unfamiliar area. However, the RGI is provided by some pre-determined options in terms of the interface between a driver and a car navigation system. Drivers occasionally pass the target intersection owing to non- or late- recognizing it. This paper is examined the position of driver's turn signal operation and intersection recognition approaching at the target intersection which is difficult to identify, as a fundamental research on developing the additional RGI connecting with the turn signal control. The field experiment was conducted to measure distances of the turn signal operation and the intersection recognition from the target intersection according to left turns, right turns, and landmarks at adjacent intersection. And glance behavior to the car navigation display was evaluated by using an eye camera. The results of the field study indicate that, most case of driving, drivers operate the turn signal until 40m to 50m before coming to the target intersection. The driving simulator experiment was performed to examine the effectiveness of providing the additional RGI when drivers did not operate the turn signal approaching at the target intersection based on the results of the field study. To provide the additional RGI is effective for the intersection identification and recognition, and expected to improve the traffic safety and the comfort for drivers.

• Proceedings of KOSOMES biannual meeting
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• 2005.05a
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• pp.129-134
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• 2005

Currently AIS needs high efficiency and safety in terms of operational management and, in the aspect of service range, it is time to minimize shadow regions through conductivity evaluation of AIS transmitter. Thus this study analyzes shadow regions and the reach of waves from stations through AIS conductivity evaluation. First, this study examines the characteristics of AIS wave and draws up methods to analyze the reach of waves according to the characteristics. Second, this study finds out service regions and shadow regions of the 22 stations across the nation by analyzing the actual data based on climate and topography. Lastly, this study summarizes the results of wave conductivity evaluation and conductivity problems and proposes improvement measures.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.69-75
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• 2007

On the wireless communication between RFID Tag and Reader, there are some existing problems with weaknesses of security such as spoofing, replay, traffic analysis, position tracking, etc., in the established hash lock related algorithm. This paper has presented the comparison and analysis of the established hash lock related algorithm for privacy and in order to make up for this, also suggested a new security authentication algorithm based on hash which has an authentication protocol and creates hash function by using random numbers received from the reader on real time and every session. The algorithm suggested here can offer a several of usefulness for RFID authentication system and it has an advantage to reduce the amount of calculations compared to established algorithm. It also uses the tags needed among a lot of tags around which are expected later and it is expected to reduce a responsibility of the server by ending unnecessary tags' operation with time based.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.6
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• pp.43-51
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• 2017

Since Korea joined the ranks of the developed countries, the interests in people with disabilities are rising. In particular, as disabled people become more active, to improve the transportation vulnerable's the right of movement have been required more strongly. Thus each municipality has been various efforts to do this. In this study we provide a understanding of each local government authority status which associated with operation of special transport systems, a call-taxi for transportation vulnerable and investigate the implementation status of mobility support system for traffic vulnerable which provided with automatic vehicle delivery. Also, with identification of automatic vehicle delivery problems the system, we design and implement a best-effort automatic vehicle delivery algorithm to improve these problems. Algorithm proposed in this study actually applied to commercial system of local governments to resolve the existing problems and to check to operate normally. The results are expected to provide to more exact and faster automatic vehicle delivery to transportation vulnerable and to improve the convenience of transportation vulnerable's movement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.291-303
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• 2006

In this paper, we analyze functional requirements of the IEEE 802.22 WRAN, and propose a downlink 프레임 structure satisfying the requirements. The proposed downlink 프레임 structure maximizes e transmission efficiency by adopting the cognative radio to assign the sub-channel by reflecting the channel environment of WRAN. We also calculate the signalling overhead for both downlink and uplink, and analyze the performances of time synchronization, frequency synchronization and cell identification based on the 프리앰블 in downlink and suggest the channel estimation method tough 프리앰블 or pilot. As a final result, e stationary beamforming (SBF) algorithm with dynamic channel allocation(DCA) is proposed. The proposed OFDMA downlink 프레임 structure with channel adaptive sub-channel allocation for cognitive radio applications is verified to meet the requirements of IEEE 802.22 WRAN, by computer simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.618-630
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• 2011

Mobile RFID system, that consists of the existing RFID reader mounted on the mobile devices such as smartphones, is able to provide the users a variety of services and convenience. Although the users can get the information about a certain product anytime anywhere, there is high probability that their privacy may be violated because their belongings with RFID tags can be scanned by other mobile readers at any time. Several RFID authentication schemes have been proposed to deal with these privacy issues. However, since the existing solutions require heavy computation on the tag side, most of them is not applicable to the general low-cost passive tags which do not have any processing unit. In this paper, we propose the efficient authentication scheme for mobile RFID system applicable to the passive tags as well as the active ones by the best use of computing capability of mobile devices. The proposed scheme satisfies the import security issues such as tag protection, untraceability, anti-traffic analysis. We also implement the proposed scheme on top of real smartphone for feasibility and show the experimental results from it.