• Journal of Advanced Navigation Technology
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• v.24 no.6
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• pp.613-619
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• 2020

Hybrid media access control (MAC) is used in internet of things (IoT) network, because of communication feature concern with data capacity and communication interval between gateway and sensor nodes and the cost efficiency. Hybrid MAC consists of TDMA and CSMA generally. The distance between gateway and sensor node is openly changed in marine IoT network. Therefore, it is needed to control the period of timeslot of hybrid MAC used in marine IoT network. In this paper, the design rule of TDMA timeslot with the variable period depending on communication distance was proposed. It was confirmed from the analysis that 72 times communication between gateway and sensor nodes is possible in LoRa network by using the proposed TDMA variable timeslot scheme.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.143-152
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• 2014

This paper introduces Database security to prevent the rapidly increasing issue of private information leakage. The Database security examined in the paper separates into DB access control area and DB encryption area which further leads the paper to analyze the factors of the two areas and suggest necessary elements for creating stable Database security. In addition, the paper examines previous DB security programs by areas and analyzes pros and cons from the tested result. The experiment indicated that while DB access control presents less degradation and reduced the need to modify the existing DBMS since the access control operates at the end point of the network, DB encryption presented strength in protecting the data from unauthorized access. On the other hand, DB access control is less useful in preventing the attack in advance which leaves the log to enable tracking afterward while DB encryption can only be operated by limited types of Database and causes degradation due to system load and shows higher percentage of failure when creating the system. This paper examines characteristics of Database security areas in order to be used as a reference for institutions or companies seeking stable Database security.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.6
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• pp.1324-1329
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• 2013

The WiMedia Alliance has specified a Distributed Medium Access Control (D-MAC) protocol based on UWB for high speed wireless home networks and WPANs. In this paper, firstly, the fair SoQ-based Distributed Reservation Protocol (DRP) for D-MAC is analyzed. And a novel SoQ-based relay transmission protocol is proposed to overcome DRP conflicts fast. In the proposed protocol, each device executes the Satisfaction of QoS (SoQ) time slot allocation algorithm independently. And, in order to give the loser device due to DRP conflicts another chance to maintain QoS resources, the proposed relay transmission protocol helps the device reserve another indirect link maintaining the required QoS resources via a relay node.

• Korean Institute of Interior Design Journal
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• v.23 no.1
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• pp.52-60
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• 2014

The purpose of this study is to analyze about the extension of user experience in the digital space. Through the digital technology and virtual space, the city's new environment is being changed. it makes people activate their aesthetic experience. Simultaneously, it elevates satisfaction levels regarding people's aesthetic experience. Research methods and settings of the range to study on the Extension of User Experience are as follows: First, establish digital space's characteristics comparing digital space at the structural change-points in modern society. Second, experience's approch way through the digital media in the contemporary space. And understand the concept about a variety of User Experience. Third. to classify the elements of access control for the user experience. Experience is being expanded through the generation process. Fourth, investigate analysis of the case studies, focused on the architecture and space design_Media installations that appear in the city park, the city's landmark buildings facade, the building facade by offering commercially applied for brand marketing_ announced through the media recently. Also, it is to look at the physical elements through digital media and to analyze the applicability of the public space. Therefore, the new approach to digital implementation shall be determined by looking in the direction of the user approaches.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.23-28
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• 2016

In this paper, we proposed the novel algorithm which controls the resolution of the HDMI(High Definition Multimedia Interface) by the channel estimation from WiFi-AP(Access Point) in the ISM(Industry-Science-Medical) band. The 2.4 and 5 GHz channel models are widely used since they have identical RF property as RSSI(Received Signal Strength Indication). Especially, the performance degradation of signal-transmission and streaming of WiFi will be occurred by the co-channel interference between AP(Access Point) and increased number of smart devices. Therefore, the optimization scheme of video format timing was designed by HDMI-CEC(Consumer Electronics Control) which considers the transmission speed of radio channel. The HDMI resolution, video quality of home-gateway and digital TV and the decision of PIP position can be maintained by the protocols between smart devices and DLNA(Digital Living Network Alliance) via proposed technique.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.151-152
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• 2007

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1083-1092
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• 2016

In this paper, the performance of the optical code-division multiple access (OCDMA) technology on a plastic optical fiber (POF) access network, which had received much attention due to its low weight, large core diameter, flexibility, easy installation, and especially its high bandwidth, is analyzed. Recently, POF was a very attractive candidate for transmission media in an access network based on OCDMA technology. But the conventional OCDMA system only allows finite units to transmit and access simultaneously according to the number of channels which are restricted by BER, and so, in this paper, to resolve this problem a novel multi-priority reservation protocol is also proposed. By using this reservation scheme and a distributed arbitration algorithm, channel collision and destination conflict could be avoided. And this protocol can efficiently support the transmission of multimedia messages that require the different time-delay. The network throughput and average delay using various system parameters have been investigated by numerical analysis and simulation experiments. These results shows that the multi-priority reservation protocol in this POF access network based on OCDMA technology is valid and efficient.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.486-490
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• 1989

In this paper, a program controlling an auto-audio media - cassette deck - by a 16 bit personal computer is studied in order to execute audio and visual learning in CAI. The results of this study are as follows. 1. Audio and visual learning is executed efficiently in CAI. 2. Access rate of voice information to text/image information is about 98% and 60% in "play" and "fast forward" respectively. 3. In "fast forward", quality of a cassette tape affects voice information access rate in propotion to motor driving speed. 4. Synchronizing signal may be mistaken by defects of tape itself.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.9
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• pp.1-12
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• 1997

The performance of Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol adopted as a draft standard of IEEE 802.11 wireless LAN, is analyzed by using mathematical method based on renewal theory. We introdude three kinds of CSMA/CA protocols basic, stop-and-wait and 4-Way handshake CSMA/CA with their mathematical analysis. First, a network of finite population is considered and then expand to infinite population. We model the CSMA/CA protocol as a hybrid protocol of 1-persistent CSMA and p-persistent CSMA protocol, and verify analaytical results by computer simulation. We have found that 4-Way Handshake CAMA/CA shows better performance than those of other two types of CSMA/CA in case of high traffic load.

• Journal of Internet Computing and Services
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• v.9 no.4
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• pp.69-77
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• 2008

I propose adding users’Media Access Control (MAC) addresses to standard X.509 certificates to provide more secure authentication. The MAC address can be added by the issuing Certification Authority (CA) to the "extensions" section of the X.509 certificate. I demonstrate that when two users with MAC address information on their digital certificates communicate, the MAC address on the first user’s certificate can be easily verified by the second user. In this way, security can be improved without markedly degrading system performance and the level of initial trust between participants in virtual communities will be improved.