• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7C
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• pp.653-663
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• 2002

The signature-then-encryption based on RSA scheme provides forward secrecy, but requires 4 modulo exponentiation operations in total, and the signcryption scheme proposed by Zheng simultaneously fulfills both the functions of digital signature and symmetric key encryption in a logically single step, and with a computational cost significantly smaller than that required by the current standard signature-then-encryption, but it can not provide forward secrecy. In this paper, we propose an enhanced signcryption scheme which can provide forward secrecy with lower computational cost and lower communication overhead comparing with those of the signature-then-encryption based on RSA, and with a similar communication overhead of Zheng's scheme. The proposed scheme can be also easily modified to the direct signature verification scheme by the recipient without using the recipient's private key. Additionally, we suggest a new design protocol with server-supported signatures which solves the CRLs(Certificate Revocation Lists) burden and provides non-repudiation of origin. This protocol with server-supported signatures also can be applied to the original signcryption scheme proposed by Zheng in order to improve security.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10C
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• pp.1395-1401
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• 2004

In The objective of this paper is to apply blind minimum output energy multiuser detection method to multicarrier direct sequence code division multiple access system. The performance of MC/DS-CDMA is reduced due to multiple access. To increase the performance of system, we need to cancel multiple user components. Blind interference canceller is able to detect the desired's information with the only minimal information of the desired user. We evaluate the performance of the proposed receiver under Gaussian channel. Simulation results show that the proposed receiver has about 6［dB］ gain of signal to noise ratio without multiple user interference and has about 3［dB］ gain of SNR with multiple user interference. Also, the result of comparing the capacity of the active users shows that the proposed method has about 2 times capacity more than conventional method. As a conclusion, simulation results show that the proposed method has better performs better than conventional method.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.460-475
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• 2016

The existing Proxy Mobile IPv6 suffers from a long handover latency which in turn causes significant packet loss that is unacceptable for seamless realtime services such as multimedia streaming. This paper proposes an OpenFlow-enabled proxy mobile IPv6 (OF-PMIPv6) in which the control of access gateways is centralized at an OpenFlow controller of a foreign network. The proposed OF-PMIPv6 separates the control path from the data path by performing the mobility control at the controller, whereas the data path remains direct between a mobile access gateway and a local mobility anchor in an IP tunnel form. A group of simple OpenFlow-enabled access gateways performs link-layer control and monitoring activities to support a comprehensive mobility of mobile nodes, and communicates with the controller through the standard OpenFlow protocol. The controller performs network-layer mobility control on behalf of mobile access gateways and communicates with the local mobility anchor in the Proxy Mobile IPv6 domain. Benefiting from the centralized view and information, the controller caches the authentication and configuration information and reuses it to significantly reduce the handover latency. An analytical analysis of the proposed OF-PMIPv6 reactive and proactive handover schemes shows 43% and 121% reduction in the handover latency, respectively, for highly utilized network. The results gathered from the OF-PMIPv6 testbed suggest similar performance improvements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.202-208
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• 2015

A wireless ship area network is required to configure and control various sensors and electrical instruments embedded or boarded in a ship. In such environment, wireless communication protocol adopting relaying function is needed because direct link or communication between two nodes is hardly guaranteed due to spatial constraints in a ship. In this study, we introduce and analyze a WiMedia Distributed MAC (D-MAC) based approach considering throughput and energy constraint of wireless communication module. Performance evaluation results demonstrate that the relay-based wireless communication protocol improves reliability of wireless communication network in a ship.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1C
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• pp.1-7
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• 2010

In this paper, the performance of the soft-decision-and-forward (SDF) protocol in the cooperative communication network with one source, one relay, and one destination, where each node has two transmit and receive antennas, is analyzed in terms of the bit error rate (BER) obtained from the pairwise error probability (PEP). For the slow-varying Rayleigh fading channel, the optimal and suboptimal power allocation ratios are determined without feedback. The optimal power allocation can be obtained by minimizing the average PEP. For the tractability, an alternative strategy of maximizing the product SNR of direct and relay links, which we call the suboptimal power allocation, is considered. Through the numerical analysis, we show that the performance gap between the suboptimal and the optimal power allocation is negligible in the high SNR region.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.532-541
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• 2009

The RFID technology has attracted much attention these days due to the far better efficiency than the bar-code and magnetic card system. As an important usage, the 433 MHz active RFID tag was already adopted to the container ports in the United States and Europe for container loading/unloading automation and equipment location. However, there is one problem to be solved for the complete automation. RFID readers support only the direct communication with tags within their RF communication range. Then there are a lot of containers and equipments such as crane, yard tractor, and forklift in ports; and because they are made of metal, they interfere the RF communication, resulting in the occurrence of the dead-zone. In the dead-zone, RFID tags cannot receive any signal from readers. There may be several solutions to resolve the dead-zone problem. Among them, this paper suggests the most economical solution where RFID tags in the dead-zone can communicate with readers via neighbor tags in the multi-hop manner The new RFID communication architecture should be carefully designed in order to maintain the compatibility with the previous standard. Our experiment shows that the proposed architecture works well even in the case where some tags are out of the RF range of reader.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12B
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• pp.1123-1130
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• 2008

Baby's diseases diagnosis has inconvenient for received direct coming to help that order expression ability was insufficiency which consciousness situation concern about the infant health because of birth rate and decrease the marriage rate and divorce rate. So in this paper through the infant crying sound about home a foundation which infant diseases develop the system comparison normal infant with take a infant that analysis the extract the voice analytics component. Especially this paper propose about the methodology for development system that infant cold, infant pneumonia, infant asthma among extract the crying sound feature part for infant respiratory diseases discussion the most easy has involved the infant. So infant respiratory put case stimulus diseases about all voice organs and experiment the analysis method through the bandwidth about phonetics analysis component that comparison normal infant with take a respiratory infant. Through these method, we were extracted to results that infant's frequency bandwidth suffering from respiratory diseases than a normal infant is short.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.225-234
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• 2008

Orthogonal Frequency Division Multiplexing (OFDM) systems utilizing direct conversion receiver suffer from frequency selective (FS) and frequency independent (FI) phase and gain imbalances caused by imperfect local oscillator and low pass filter. In this paper, we analyze the impacts of the transmit/receive IQ imbalances on the system and propose the estimation and compensation schemes for those imbalances. The preamble signals coded by Alamouti scheme in the frequency domain could be used in the estimation of relatively large IQ imbalances with FS and FI characteristics and the estimation results are used for the compensation of distortions caused by the FI and FS IQ imbalances. The optimal maximum likelihood (ML) receiver or suboptimal ordered successive interference cancallation (OSIC) receiver utilizing the estimation results show symbol error rate (SER) performance improvement compared to zero-forcing (ZF) technique due to diversity gain inherent in the frequency domain IQ imbalances combined with the frequency selective channels.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2008.05a
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• pp.116-122
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• 2008

As a model house has attempted a role change from a conceptual perspective as a housing cultural center starting from the 90ties, it began to direct the change into a high end building. In particular, large construction companies have recently invested on an unimagined scale, unlike in the past, in building a model house and pursued the construction of new attractions of cities as well as the upgrade of a brand image by hiring and implementing the designs of celebrity architects or designers. In addition, they have been in pursuit of a change by enhancing the satisfaction and pride of residents by offering spaces and programs for various cultural arts for apartment residents or potential customers and having them participate in those programs. This study aims to expound on the possibility of the utilization of a housing cultural center as a local complex community center by analyzing the spatial organization and the operational program of a housing cultural center appearing since the 90ties. With this aim, the study analyzed the cases of a complex community center and the program and the operational method of a housing cultural center within the case study in order to propose the possibilities for the utilization of a local complex community center. The elevation of the cultural and economic level of citizens and a rapid social change are shown as various demands for welfare, and the subsequent social physical change has led to the expansion of a space as a complex community. A housing cultural center is also directed to grow as a complex community center from the perspective of diverse demands and participations of consumers, and prepares a field for a broad spectrum of communications from the perspective of housing and cities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.569-574
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• 2018

This paper proposes and implements a LoRa-based emergency exit guide system which can direct the optimal refuge path accounting for the real state of the fires. Each 4-way emergency exit guide sign presents a right direction through one of four LED signs toward the possible exit dynamically calculated by the shortest path algorithm. We constructed a simulation environment with 8 spots of the emergency exit guide signs and 2 exits, which can simulate variant cases of fire accidents, and showed that the proposed algorithm can presents the right guidance for each emergency exit guide sign. We also evaluated the performances of LoRa-based wireless communications using a self developed communication module in the various indoor and outdoor environments. The proposed system can be applied to small and medium sized buildings as well as larger ones in terms of cost efficiency, in which there's no needs to invest for the complex equipments except only sensors and emergency exit guide signs.