• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.801-809
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• 2010

Limitation of optical phase conjugation for implementation of wideband and long-haul WDM transmission system is symmetric distribution of optical power and local dispersion with respect to optical phase conjugator (OPC). This limitation forces OPC to place at midway of total transmission length. This paper shows that the limitation of optical phase conjugation is overcame by applying optimal net residual dispersion (NRD) into transmission links based in inline dispersion management (DM). Optimal NRD related with OPC position is decided by combination of precompensation and postcompensation. It is confirmed that optimal NRD depends on launch power of WDM channels and system performance criterion as well as OPC position. That is, in case of 1 dB eye opening penaty (EOP) as a performance criterion for WDM channels with 0 dBm launch power, it is confirmed that OPC is allowed to place at anywhere of 1000 km by applying best NRD related with exact OPC position into transmission links. And, it is confirmed that, under 3 dB EOP criterioin for WDM channels with 3 dBm launch power, OPC is allowed to place at 350~700 km by applying NRD between 100 ps/nm and 200 ps/nm into transmission links, though that NRD value is not best combination of precompensation and postcompensation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11A
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• pp.1072-1078
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• 2008

In this paper, we propose an efficient superposition coding multiplexing(SCM) method based on power allocation in descending order for fading broadcast channels in which per-user minimum and maximum rate constraints are considered in order to maximize the transmission effectiveness. It consists of three steps as follows. In the first step, a user group is selected to maximize the number of users with whom a transmitter can communicate instantaneously. In the second step, per-user power allocation for each user is done in descending order of transmit power by determining a maximum allowable interference power from all subsequent interfering users in order to guarantee its corresponding minimum rate, and then a residual power is calculated. The final step is performed if some power remains even after the second step. In this step, additional power allocation is performed up to the maximum transmit power to provide the maximum rate to the corresponding user, again in ascending order, starting from the last user in descending order. But, this method does not require power reallocation to subsequent users because tentative power allocation in the second step has been performed in descending order to guarantee the minimum rate for each user, taking into account the maximum allowable interference power from all the subsequent users. Therefore, the proposed method gets more efficient in term of computational complexity when per-user minimum as well as maximum rate constraints exist, especially as the number of users increases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1444-1455
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• 1999

In the standard location strategy such as IS-41 and GSM, Home Location Register(HLR) and Visitor Location Register(VLR) databases are used to manage the location of mobile terminals. The primary goal that location management schemes investigate is to reduce the cost of database access and the traffic for signaling network. When mobile terminals move frequently, one of problems in the standard location management scheme is that HLR database is highly updated and the traffic in signaling network can be occurred significantly due to high message transfer rate between HRL and VLR. As a solution to these problems, this paper proposes the location management scheme using VLR Gateway(VG) to reduce the both traffics of HLR update and signaling network which are resulted from location registration requirements of mobile terminals whenever they cross their registration area boundary. VG is a kind of database that is placed between HLR and VLR. It integrates one or more registration area defined in a system into one group and plays a role on behalf of HLR in a integrated registration scope so that the call delivery and the movement of mobile terminals are possible without HLR access in the scope. In order to evaluate performance of IS-41 and proposed scheme, we simulate two schemes based on wide range of call to mobility ratio. Its experiment result shows that in the proposed scheme total database cost increased slightly whereas HLR and signaling traffic decreased remarkably.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1380-1386
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• 2009

In this paper, we propose a CQS(Calendar Queue Scheduler) architecture which was designed for processing multimedia and timing traffic in home network. With various characteristics of the increased traffic flowed in home such as VoIP, VOD, IPTV, and Best-efforts traffic, the needs of managing QoS(Quality of Service) are being discussed. Making a group regarding application or service is effective to guarantee successful QoS under the restricted circumstances. The proposed design is aimed for home gateway corresponding to the end points of receiver on end-to-end QoS and eligible for supporting multimedia traffic within restricted network sources and optimizing queue sizes. Then, we simulated the area for each module and each memory. The area for each module is referenced by NAND($2{\times}1$) Gate(11.09) when synthesizing with Magnachip 0.18 CMOS libraries through the Synopsys Design Compiler. We verified the portion of memory is 85.38% of the entire CQS. And each memory size is extracted through CACTI 5.3(a unit in mm2). According to the increase of the memory’sentry, the increment of memory area gradually increases, and defining the day size for 1 year definitely affects the total CQS area. In this paper, we discussed design methodology and operation for each module when designing CQS by hardware.

• Management & Information Systems Review
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• v.33 no.3
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• pp.189-208
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• 2014

This research is on the relationship among organizational communication and organizational citizenship behavior focused on the moderating effect of transformational leadership. The objective of this research is to conduct positive verification of organizational communication impacting on organizational citizenship behavior. Also, to perform positive verification on moderating effect of transformational leadership. The variables are downward communication, upward communication, unofficial communication, organizational citizenship behavior including participatory actions, altruistic behavior, mindful behaviors, and transformational leadership. It was verified on survey of 232 peoples. The verification and analysis results will be provided to impact of organizational communication on organizational citizenship behavior, the downward communication impacts all elements of citizens' behaviors, and upward communication impacts of participatory actions. On the other hand, the unofficial communication did not impact at all. Moreover the results of moderating effect of transformational leadership. The transformational leadership act as moderator in downward, upward communications. but did not act as a moderator on the unofficial communication. The research suggests to use transformational leaderships to commanders and leaderships at military organizations to put efforts on active communication in order to manage unit more effectively and efficiently and to make members of organization to voluntarily. It is assessed that this paper will serve as a reference to whoever in military reform group or organization working for military developments working for creating elite forces.

• Korean journal of communication and information
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• v.60
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• pp.52-74
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• 2012

Legislation needs to be understood within a political, societal relationship among lawmaking bodies rather than by legal provision itself. In order to examine features and functions of communication in the process of legislation, this study conducted focus group interviews with experts as well as in-depth individual interviews. The result of this research as follows: First, the study found that although the domestic legislative process has been made by active interactions among lawmaking subjects, it was hard to conclude that this procedure is providing effective and productive legislative agenda because of chaotic communications made along the process. Second, the study found that national legislative process has been gradually moving, although restricted, to an open political space, the National Assembly, from a closed space, the executive branch. Third, the study found a remarkable feature including growing influence of experts groups and civic organizations in the legislative process. It is a significant change that legislative staff such as National Assembly aides, investigators, expert committeemen and deputy director generals played a role of "insiders," unnoticeably influencing the legislative process, and that civic organizations and NGOs, which have been excluded in the previous legislative processes, emerged as a new influencing circle in the process. Lastly, the study found that media organizations, in the process of developing agenda, had a strong impact on the National Assembly as a subject forming public issues and as a messenger of the legislative agenda while they played a limited role in affecting the government. This study discusses why communication in the domestic legislative process is important and what are some hindering and facilitating factors in the process.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.91-102
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• 2012

Generally today's culture and the arts industry has been focusing more on economic value than the arts. Therefore this paper will elucidate the meaning of the culture and the arts can be a break though which can only include commercial and economic values but transcend its values ultimately. First of all, this paper will suggest an advanced 3D stereoscopic images by analysis of examples and environments of realistic media arts. Looking into the changes of related technologies and market environments, the motion-recognition technology, as seem in SF film "Minority report", has become a feasible technology. In the past, 3D stereoscopic images were shown in the theme park theatre and exhibition halls for group viewing. but recent 3D TV and display devices have changed those environments to personal. Since domestic researches of realistic media art has been little, this paper will analyze them respecting to three broad classifications. The results are : Firstly, in CAVE method, more impact capabilities of spectators are expected that they can manipulate interactive interfaces freely and the physical movements of spectators can operate interactively. Secondly, inter-network communications and expansion of viewers' perceptions are predicted by way of HMD method, sensor suites and communication equipments. Thirdly, combinations of HMD and motion tracking utilization is foreseen. With the convergent usages of these three features, we can prospect the possibilities of interactive 4D that spectators wearing 3D stereoscopic display devices can experience and make their own 3D stereoscopic images actively at the point of their views.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.20 no.5
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• pp.17-22
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• 2002

만약 사용자가 원하는 멀티미디어 콘텐츠를 원하는 시간에 TV를 통해서 볼 수 있게 된다면, 다시 말해서 보고 싶을 때, 보고 싶은 방송을 포함한 멀티미디어 콘텐츠를 원하는 시간에 바로 볼 수 있게 된다면 사용자는 방송시간에 맞추어 TV를 보지 않아도 되고 원하는 콘텐츠를 검색하느라 시간을 보낼 필요도 없어질 것이다. 예약 녹화의 경우에는 시간정보를 가지고 미리 예약을 해야 하는 경우이므로 이와는 다른 경우라 하겠다. 이러한 서비스는 바로 디지털 콘텐츠와 이를 가정에서 저장할 수 있는 장치의 발달이 바탕이 되고 있다.(표 1 생략, 원문이미지 참조) 표 1은 영국의 BBC사에서 1998년에 조사한 자료로 디지털 멀티미디어 데이터를 저장하고 재생할 수 있는 저장장치의 가격과 용량의 전망을 나타낸다. 여기에서 데이터는 5.5 Mbps급의 MPEG-2 스트림을 기준으로 하였다. 표 1에서 보수적 견해는 매 18개월마다, 현실적 견해는 매 10개월마다 동일 가격의 용량이 2배가 되는 것으로 계산한 것이다. 여기서 보듯 저장장치의 가격 대비 성능이 갈수록 나아지고 있어 가정에서 멀티미디어 콘텐츠를 저장할 수 있는 가정용 서버의 등장이 멀지 않았음을 보여준다. 1999년 가을에 활동을 접은 DAVIC의 마지막 활동이 바로 이러한 저장장치를 이용한 "TV Anytime Service"였다 . Anytime Ser vice란 저장장치를 통해 사용자가 원하는 콘텐츠를 저장해 놓았다가 사용자가 원하는 시간에 언제나 볼 수 있다는 개념이다. 이를 소비자관점에서 보면 Personalized service라고 할 수 있다. 이어 1999년 여름에 창설이 된 "TV Anytime Forum"이라는 단체에서 이러한 저장장치를 이용한 서비스를 위한 환경을 구축하고 있다. TV Anytime Forum은 가정에서 저장장치가 있는 단말인 PDR(Personal Digital Recorder)을 이용한 서비스, 즉 Anytime Service 위한 응용을 가능하게 하기위한 콘텐트 개발자에서부터 가전기기에 이르는 분야에서 Interoperable한 규격을 만들어 보자는 것이 그 목적이다. 특히 여러가지 디지털미디어 전달방식, 예를 들어 DVB, ATSC, ARIB 등에 독립적인 규격을 만드는 것을 원칙으로 하고 있다. 1999년 7월에 첫 번째 회의를 하면서 설립이 되었다. 2001년 말 기준으로 BBC, NHK, Microsoft, Sony, IBM, Phillips, NTT, Intel, Canal+, Tivo, 대우전자, 삼성전자, LG전자, KETI, ETRI 등 콘텐츠 사업자, 방송업자, 네트웍 사업자, 가전업체, 소프트웨어 개발회상에 이르기까지 총 157개 회원사로 구성되어 있으며 년 6회 회의를 개최한다. 2000년 11월에는 서울에서 회의를 개최하였으며 2003년 6월에 다시 한국에서 개최하기로 확정되어 있다. 본 글에서는 이러한 Anytime Service 환경이 구축되었을 때의 각 산업별로 얻을 수 있는 이득에 대해서 알아보고 TV Anytime Forum의 각 Working Group들의 작업 내용들, 그리고 지난 1월에 열렸던 15차 회의의 결과들에 대해서 살펴보고 국내의 TV Anytime 활동에 대해서 간단하게 소개하고 마치도록 하겠다. 현재 디지털 방송기술, 비디오 스트리밍 기술이나 MPEG 등과 같은 기술수준으로도 충분히 이러한 서비스를 시작할 수 있으며 소비자들도 이러한 욕구를 서서히 느끼고 있다. 정보와 서비스를 선택할 수 있게 만들자는 목표를 설정하고 있다. 이러 목표는 통신$.$컴퓨터$.$멀티미디어 기술발전으로 가능하게 되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.8
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• pp.1588-1596
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• 2015

In the Internet of Things (IoT), resource-constrained devices such as sensors are capable of communicating and exchanging data over the Internet. The IETF standard group has specified an application protocol CoAP, which uses UDP as a transport protocol, allows such a lightweight device to transmit data. Also, the IETF recommended the DTLS binding for securing CoAP. However, additional features should be added to the DTLS protocol to resolve several problems such as packet loss, reordering, fragmentation and replay attack. Consequently, performance of DTLS is worse than TLS. It is highly required for lightweight devices powered by small battery to design and implement a security protocol in an energy efficient manner. This paper thus discusses about DTLS performance in the perspective of energy consumption. To analyze the performance, we implemented IEEE 802.15.4 based test network consisting of constrained sensor devices in the Cooja simulator. We measured energy consumptions required for each of DTLS client and server in the test network. This paper compares the energy consumption and amount of transmitted data of each flight of DTLS handshake, and the processing and receiving time. We present the analyzed results with regard to code size, cipher primitive and fragmentation as well.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.574-580
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• 2016

In this paper, we will introduce the system that can control multiple vehicles on the road through Single Board Computers and V2I (Vehicle-To-Infrastructure). Also, we will propose the group evasive maneuver decision algorithm, which plays a critical role in deciding whether the vehicles in the system have to conduct evasive maneuvers to avoid obstacles on the road. In order to test this system, we have utilized Wi-Fi and TCP/IP for establishing the communication between multiple vehicles and the relay server, and observed their driving states on the road with obstacles. During the experiments, we have discovered that our original decision algorithm possesses high failure rate when there is frequency interference in ISM (Industrial Scientific Medical) band. In order to reduce this failure rate, we have implemented the data transition detector. This paper will focus on how the use of data transition detector can affect the reliability of the system under the frequency interference of ISM band. If this technology is improved and applied in the field, we will effectively deal with such dangerous situations as multiple collision accidents through vehicle-to-vehicle communication or vehicle-to-infrastructure communication. Furthermore, this can be applied to the autonomous driving technologies. This can be used as the reference data for the development of the similar system.