• Journal of Internet Technology
• /
• 제20권5호
• /
• pp.1535-1545
• /
• 2019

Recently, the diverse kinds of applications in multimedia computing have been developed for visual surveillance, healthcare, smart cities, and security. Video conferencing is one of core applications among multimedia applications. The Quality of Service of video conferencing is a major issue, because of limited network traffic. Video conferencing allow a large number of users to converse with each other. However, the huge amount of packets are generated in the process of transmitting and receiving the photographed images of users. Therefore, the number of packets in video conferencing needs to be reduced. Video conferencing can be conducted in virtual reality by sending only the control signals of virtual characters and showing virtual characters based on the received signals to represent the users, instead of the photographed images of the users, in real time. This paper proposes a method that determines representative photographed images by analyzing the collected photographed images of users, using KMedoids algorithm and a decision tree, and expresses the users based on the analyzed images. The decision tree used for video conferencing are generated automatically using the proposed method. Given that the behaviors in the decision tree is added or changed considering photographed images, it is possible to reproduce the decision tree by photographing the behavior of the user in real-time. In an experiment conducted, 63 consecutively photographed images were collected and a decision tree generated by using the silhouette images of the photographed images. Indices of the silhouette images were utilized to express a subject and one index was selected using a decision tree. The proposed method reduced the number of comparisons by a factor of 3.78 compared with the traditional method that uses correlation coefficient. Further, each user's image could be outputted by using only the control image table of the image and the index.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제10권7호
• /
• pp.2972-2991
• /
• 2016

WLAN is the best choice in the place where complex network is hard to set up. Intelligent terminals are more and more assembled in some areas now. However, according to IEEE 802.11n/802.11ac, the access-point (AP) can only serve one user at a single frequency channel. The spectrum efficiency urgently needs to be improved. In theory, AP with multi-antenna can serve multiple users if these users do not interfere with each other. In this paper, we propose a user clustering scheme that could achieve multi-user selection through the mutual cooperation among users. We focus on two points, one is to achieve multi-user communication with multiple antennas technique at a single frequency channel, and the other one is to use a way of distributed users' collaboration to determine the multi-user selection for user clustering. Firstly, we use the CSMA/CA protocol to select the first user, and then we set this user as a source node using users' cooperation to search other proper users. With the help of the users' broadcast cooperation, we can search and select other appropriate user (while the number of access users is limited by the number of antennas in AP) to access AP with the first user simultaneously. In the network node searching, we propose a maximum degree energy routing searching algorithm, which uses the shortest time and traverses as many users as possible. We carried out the necessary analysis and simulation to prove the feasibility of the scheme. We hope this work may provide a new idea for the solution of the multiple access problem.

• 한국콘텐츠학회논문지
• /
• 제21권11호
• /
• pp.100-111
• /
• 2021

본 연구는 이용자의 유튜브 구독에 대한 학술적 논의가 부족한 상황에서 구독 채널 수와 구독 만족도에 영향을 미치는 변인을 살펴봄으로써 새로운 논의의 장을 이끌고자 하였다. 이를 위해 유튜브 이용자들의 구독 채널수와 구독 만족도에 영향을 미치는 요인을 유튜브 이용 요인, 구독 동기 요인, 유튜브 채널 평가 요인으로 구분하고, 각 요인의 상대적 영향력을 살펴보기 위해 위계적 회귀분석을 실시하였다. 분석 결과는 다음과 같다. 첫째, 구독 채널 수에는 유튜브의 이용량과 편의성 구독 동기가 정적 영향을 미쳤다. 둘째, 구독 만족도에 영향을 미치는 요인은 편의성 구독 동기와 유튜버와의 소통 동기, 그리고 유튜브의 지각된 유용성으로 나타났다. 본 연구의 실무적 의의는 변화하는 뉴미디어 환경의 플랫폼과 채널 운영자에게 도움이 될 수 있다는 점과 뉴미디어 환경에서의 상호작용 연구의 외연을 확장했다는 점이다.

• 한국문헌정보학회지
• /
• 제32권1호
• /
• pp.169-187
• /
• 1998

본 연구의 목적은 전자형 색인초록이 도서관 및 정보기관에 도입되어 있음에도 불구하고 계속 인쇄형 색인초록을 이용하는 이용자는 어떤 개인적 특성을 보이고 있으며, 어떤 행태를 지니고 있는지를 전자형 색인초록 이용행태와 비교함으로써 인쇄형 색인초록이 지니고 있는 특성을 밝히는데 있다. 결론을 요약하면 이용자들은 논문작성시 확실한 연구논제를 정하지 못한 상태에서 연구의 주제를 얻기 위하여 인쇄형 색인초록을 이용하는 반면, 확실한 논제가 정해진 상태에서는 선행연구조사와 같은 포괄적인 조사를 하기 위해서 전자형 색인초록을 이용하고 있고 인쇄형 색인초록 이용자들은 탐색과정 중 자신에게 필요한 문헌인지 아닌지를 결정하는 판단력으로 인하여 탐색결과 만족도가 전자형 색인초록 이용자보다 다소 더 높으며, 전자형 색인초록 이용자는 인쇄형 색인초록 이용자보다 탐색결과 분석을 위해 별도의 시간을 더 많이 할애하고 있다. 전자형 색인초록 이용자는 인쇄형 색인초록 이용자보다 탐색실패 경험이 더 많았으며, 탐색실패 후 각 유형의 색인초록 이용자 모두 높은 응답율로 다른 색인초록을 통한 재탐색을 시도하였다. 인쇄형 색인초록 이용자는 전자형 색인초록 이용자에 비해 온라인 탐색지식이 월등하게 적은 것으로 나타났다.

• 한국조경학회지
• /
• 제15권2호
• /
• pp.67-78
• /
• 1987

This study was executed to measure the user\`s impact natural environment in National Park Campsite. Therefore, we choose Mt. Chiak National Park and the campsite in the district of Temple Ku-Ryong as a model of analysis, which is made by ecological approach, the number of the user has influence on the environment near the campsite. The result are as follows : 1. The more the number of users becomes, the more Na, Ca, Mg ion concentration and pH in the soil increase and the less K ion becomes. 2. Litter and humus depth, litter coverage, herb coverage, soil hardness, the surface of the ground layer and tree species numbers, density and coverage of lower layer shows a sensitive reaction to the number of the users. 3. The research shows that the tolerant trees against campsite impact are Lespedeza maximowiczii, Zanthoxylum schinifolium Staphylea bumalda, Smilax sieboldii, Quercus aliena, Euonymus oxyphyllus, Weigela subsessilis and Securinega suffruticosa, and the sensitive trees are Stephanandra incisa, Rubus trichocarpa, Rubus crataegifolius, Rhododendron mucronulatum, Styrax obassia, Acer palmatum, Lindera obtusiloba, Rhododendron suhlippenbachii, Rhus japonica and Callicarpa japonica. 4. The high density of the users made the simplication of a vegetation structure. So, as the number of the user increase the species showed severe heterogeniety between the heavy-use and nonuse site. 5. As considering the landscape management about campsite and surrounding area on the way of analysis of national landscape aspect and succession sere according to ecological aspect, it may be desirable that Pinus densiflora forest be conserved as Pinus densiflora landscape and mixed forest produce natural scenery with succession sere.

• 한국IT서비스학회지
• /
• 제10권4호
• /
• pp.119-131
• /
• 2011

When your company buys packaged software, the company needs to determine how many software licenses must be purchased. If the quantity is too small, it will be not enough for the users to access the programs at anytime within the company. Conversely, if the quantity is too large, they will waste a lot of money. In this paper, we surveyed several number of researchers of K institute and derived the using pattern of a specific packaged software. We estimated a proper number of packaged software licenses by Erlang Loss Function, the Engset Model, and simulation model. With the results of the three methodologies, we were able to empirically verify economic benefits of packaged software purchase by comparing NPV (Net Present Value) between user licenses and network licenses. Consequently, TCO of user licenses is much higher than that of network licenses. We had probabilistically calculated proper number of licenses based on the using pattern of users. Hence, this paper will be useful for decision makers who are going to determine package software's type and quantity from an economic perspective.

• 한국통신학회논문지
• /
• 제40권4호
• /
• pp.646-652
• /
• 2015

본 논문은 다중 사용자 MIMO 시스템에서 사용자 선택을 위해 필요한 precoding matrix index (PMI)/channel quality indication (CQI)의 보고 방식에 따른 성능을 분석한다. 이러한 분석을 통해 셀 내의 단말의 수, 선택되는 사용자의 수, 그리고 코드북(codebook)의 크기가 Best Companion Grouping (BCG)방식 스케쥴링의 성능에 복잡하게 영향을 미치는 것을 확인한다. 이에 따라 셀 내의 사용자 수와 코드북의 크기에 따라 동시에 스케쥴링 되는 사용자들의 그룹이 형성될 수 있는 확률이 달라지는 것을 확인할 수 있으며, 피드백 오버헤드가 주어졌을 때 이에 따라 피드백하는 PMI의 수와 사용하는 코드북의 크기를 적응적으로 선택함으로써 시스템의 평균 수율 성능을 최적화할 수 있음을 보였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
• /
• pp.165-168
• /
• 2000

The bit error rate(BER)of the data passed through Wideband-Code Division Multiple Access (W-CDMA) system with turbo-codes structure is presented. The performance of turbo-codes under W-CDMA system is estimated for various users and iteration numbers of decoding. The channel model is Additive White Gaussian Noise(AWGN) and Rayleigh fading channel. When iteration number increases, bit error probability of turbo-codes decreases. and when the number of users increase, bit error probability of turbo-codes increases.

• International Journal of Computer Science & Network Security
• /
• 제22권2호
• /
• pp.327-333
• /
• 2022

Internet Protocol Television (IPTV) has emerged as a personal entertainment source for home users. Streaming IPTV content over a wireless medium with good Quality of Service (QoS) can be a challenging task as IPTV content requires more bandwidth and Wireless Local Area Networks (WLANs) are susceptible to packet loss, delay and jitter. This research presents the capacity of IPTV using User Datagram Protocol (UDP) and TCP Friendly Rate Control (TFRC) over IEEE 802.11ac WLANs in good and bad network conditions. Experimental results show that in good network conditions, UDP and TFRC could accommodate a maximum of 78 and 75 Standard Definition Television (SDTV) users, respectively. In contrast, 15 and 11 High-Definition Television (HDTV) users were supported by UDP and TFRC, respectively. Performance of UDP and TFRC was identical in bad network conditions and same number of SDTV and HDTV users were supported by TFRC and UDP. With background Transmission Control Protocol (TCP) traffic, both UDP and TFRC can support nearly the same number of SDTV users. It was found that TFRC can co-exist fairly with TCP by giving more throughput to TCP unlike UDP.

• International Journal of Computer Science & Network Security
• /
• 제22권12호
• /
• pp.212-216
• /
• 2022

Space based constellation network is a kind of ad hoc network in which users are self-organized without center node. In space based constellation network, users are allowed to enter or leave the network at any given time. Thus, the number of active users is an unknown and time-varying parameter, and the performance of the network depends on how accurately this parameter is estimated. The so-called problem of active user identification, which consists of determining the number and identities of users transmitting in space based constellation network is discussed and a novel active user identification method is proposed in this paper. Active user identification code generated by transmitter address code and receiver address code is used to spread spectrum. Subspace-based method is used to process received signal and judgment model is established to identify active users according to the processing results. The proposed method is simulated under AWGN channel, Rician channel and Rayleigh channel respectively. Numerical results indicate that the proposed method obtains at least 1.16dB E_b/N₀ gains compared with reference methods when miss alarm rate reaches 10^-3.