• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.157-163
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• 2003

IEEE 802.11a Distributed Coordination Function(DCF) Protocol을 사용하여 Real-Time MultiMedia Data의 전송을 수행할 경우, DCF Protocol의 적합하지 못한 Mechanism에 의하여, Data 전송의 극대화를 이루지 못한다. Retransmission이 반복되는 경우, Binary Slotted Exponential Backoff Mechanism은 거대한 Packet Delay와 Jitter의 원인이 되며 Automatic Repeat Request(ARQ) 방식의 Ack Mechanism은 MultiMedia Data를 전송하기에 적합하지 못하다. 본 논문은 위와 같은 문제점을 해결하기 위하여 Real-Time MultiMedia Data을 주로 전송하는 STA에 따른 Real-Time/Non-Real-Time(RT/NRT) Station(STA)의 구분과 보내고자 하는 Real-Time MultiMedia Data의 Network Traffic Load(The Required Bandwidth)를 고려하여, Modified DCF(mDCF) Protocol의 Modified Backoff(mBackOff), Modified BlockAck(mBlockAck) Mechanism을 제시함으로서, Data 전송의 극대화를 제공하며, 또한 IEEE 802.11a와의 호환성을 제공한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.160-163
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• 2017

개인적인 활동들 전반에 걸쳐 스마트폰이 PC를 대체하고 있는 것으로 조사되었다. 스마트폰 사용자의 증가와 함께 다양한 어플리케이션이 개발되고 있고, 알람 어플리케이션은 혼자서 생활하는 시간이 많은 현대인들에게는 꼭 필요한 어플리케이션 가운데 하나이다. 이에 본 논문에서는 현대인들의 생활 패턴을 고려하여 기본적인 알람기능에 빅데이터를 이용한 알람음악 랭킹 제공, 날씨와 교통정보 제공, 일정관리 기능 등을 추가한 '빅데이터를 이용한 스마트 알람 시스템'을 개발하였다. 본 논문에서 개발한 어플리케이션은 바쁜 현대인의 아침시간에 여러 개의 어플리케이션을 사용할 필요가 없도록 사용자 편리성을 높인 알람 어플리케이션으로 개발하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.538-541
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• 2013

택시는 많은 사람들이 이용하고 있는 교통수단이다. 특히 버스나 지하철 같은 대중교통 운행시간이 끝나는 야간에는 택시의 이용률이 더 많을 수밖에 없다. 그러나 최근 택시를 이용한 범죄가 많이 발생하면서 택시에 대한 사람들의 불안감이 커져가고 있다. 본 논문에서는 스마트폰을 이용하여 택시를 보다 안전하게 이용할 수 있는 시스템과 앱을 설계하였다. 스마트폰의 NFC 기술을 이용하여 인증된 택시에 부착된 NFC 태그를 인식하게 되면 택시정보와 탑승정보를 미리 등록된 지인들에게 실시간으로 전송하게 된다. 그로 인해 탑승자들은 보다 더 안전하게 택시를 이용하게 될 것을 기대할 수 있다.

• Journal of Korea Multimedia Society
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• v.24 no.11
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• pp.1526-1537
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• 2021

Due to the difference between the underwater communication environment and the terrestrial communication environment, the radio communication mainly used on the ground cannot be used in underwater. For this reason, in the underwater communication environment, various communication media such as acoustic waves, infrared rays, light and so on has been studied, but there exist several difficulties in operating them individually due to their physical limitations. The concept for overcoming these difficulties is the very underwater multi-media communication, a method to select a communication medium best suitable for the current underwater environment among underwater communication multimedia whenever there occurs underwater communication failure. In this paper, we present an underwater multi-media communication network based on star topology and a fragmentation and reassembly technique to solve the problems caused by the different MTU (Maximum Transmission Unit) sizes among different underwater communication media. We also present the estimations and analysis on processing times in each of fragmentation and reassembly and the total data amount for transmitting fragments in our proposed underwater multi-media communication network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.950-956
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• 2015

In this paper, a WiMedia Distributed-MAC (D-MAC) protocol is adopted for development of a seamless N-screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a ATMT (Asynchronous Traffic Multi-hop Transmission) technology is proposed and analyzed. In this system, a WiMedia ATMT D-MAC bridge transmits control and managing information to various sensors and instruments, from a central integrated ship area network station. For this technology, a time slot allocation scheme for WiMedia asynchronous traffic and a multi-hop resource reservation scheme are combined to evaluate the performance of each scheme. From simulation results, the proposed ATMT scheme enhances performances in viewpoints of N-screen asynchronous data latency and throughput, compared to the conventional WiMedia D-MAC system.

• Journal of Korea Multimedia Society
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• v.23 no.7
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• pp.819-829
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• 2020

Underwater communication is necessarily useful for various application domains such as saving of human lives from underwater disasters, marine resource exploration, underwater military fields, underwater environment or ecosystem monitoring, fish farm monitoring and management, etc. Even though the acoustic wave has been the main underwater communication media until now, several media such as optical waves, VLF/ELF waves, magnetic fields, and infrared rays also began to be treated as possible media for underwater communication. If these underwater communicate-possible media are used mixing together, the underwater communication can be much more reliable and efficient through complementing the disadvantages of each communication media with advantages of other communication media. In fact, mixing and using multi-media for underwater communication requires the data flow control in the connection process of different media due to their communication speed gaps and bandwidth differences, and, specially, in the flow control, the appropriate message fragmentation technique is required inevitably. For this reason, this paper presents a fragmentation framework and technique necessary to the flow control in the underwater multi-media communication. In addition, through its implementation and experiments, this paper shows the feasibility on the realization of the multi-media based underwater communication.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1574-1583
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• 2017

This paper proposes how to develop a multi-sensory virtual reality system based on realistic media that can improve the sense of immersion and reality experienced by the user. We suggest four types of multi-sensory virtual reality system; a realistic media experience system which provides sensory experiences to user by interlocking the media file with the sensory informations and reproducing the sensory information suitable for the scene, a real image-based panorama experience system which maximizes the sense of reality, an experience ball system in which users engage themselves into the system environment to lead the story and immersion of the content through interaction with the system, and a cultural heritage experience system based on hand movement recognition. The suggested systems can be applied in a various area such as education, advertisement, culture and arts, performance, exhibition, sports, game, 4D Experience Center, and so on. We supposed that it can contribute to create a variety of sensible contents services in the realistic media industry through the convergence of media, contents, and devices.

• Proceedings of the Korea Society of Design Studies Conference
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• 2002.05b
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• pp.274-275
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• 2002

• Proceedings of the Korea Multimedia Society Conference
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• 2002.11b
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• pp.767-770
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• 2002

본 논문에서는 RTSP 프로토콜을 제어하기 위한 서버 시스템을 IOCP 기반의 Multi-Thread 기법을 이용하여 구현하는 방법을 소개한다. 다수의 클라이언트에 대한 응답을 Thread로 구성하는 부분에서 Multi-Threading을 이용함으로써 수행 속도를 높이고 Winsock2에서 제공하는 IOCP(T/O Completion Port)를 이용하여 견고하고 확장이 용이한 RTSP(Real Time Streaming Protocol) 스트리밍 서버를 개발하였다.

• Journal of Agricultural Extension & Community Development
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• v.17 no.1
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• pp.75-101
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• 2010

This study tried to analyze the learning effectiveness of multi-media based class by comparing with traditional classroom method. The "Basic Agricultural Technology" course that is one of the required courses of agricultural high school was selected and its contents were digitalized on MS Powerpoint for multi-media based class. The thirty students were sampled for each experimental and control groups. The homogeneity and learning achievement of sample groups were tested for experiment. Same teacher took the classes of two groups and delivered same contents of course. Only difference between two groups was the delivery method, one is traditional classroom teaching method and the other was the multi-media based class. The learning achievements and satisfaction of sample were post-tested in order to analyze the learning effectiveness by comparing two teaching methods. The results showed that there was a significant difference between experimental and control group in learning achievement after ANCOVA controlled pre-test as covariance(F=5.08, p<.05). It means that the learning achievement of multi-media based class was higher than that of traditional classroom group. The results also showed that a significant difference in students’ satisfaction between two groups (t=5.57, p<.001). This study concluded that using multi-media in class could produce more learning achievements and satisfaction of students than traditional classroom method.