• Journal of Korea Technology Innovation Society
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• v.8 no.3
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• pp.1060-1086
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• 2005

In this paper, we attempt to predict the future of broadband access market where new convergence access technologies and additional services are introduced, based on consumer preferences. Conjoint analysis and mixed logit model is used for estimation, From the results, consumers value convergence access technologies such as PLC and wireless LAN, and TV-related service, However, valuation on new beneficial features of convergence access technologies is not enough to overcome their technological inferiorities in data transfer speed and quality stability at current technological stage, Additionally, consumer preferences are so heterogeneous that differentiated business strategies are required, Finally, some managerial and policy implications are presented.

• Journal of information and communication convergence engineering
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• v.2 no.2
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• pp.76-79
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• 2004

The DS-SS (Direct Sequence Spread Spec1nun) transmitter is part of a low data rate (∼150 kbps - burst rate and 64 bps - average data rate) wireless communication system. It is traditionally implemented using Digital Signal processing chip (DSP). However, with rapid increase in variety of services through cell phones, such as, web access, video transfer, online games etc. demand for higher rate is increasing steadily. Since the chip rate and thereby the sampling rate requirements of the system are fairly high, the transmitter should implemented using Field programmable Gate Arrays FPGAs instead of a DSP. This paper shows the steps taken to get a working prototype of the transmitter unit on a FPGA based platform.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06b
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• pp.357-362
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• 2010

본 논문에서는 VGA 해상도의 컴퓨터 영상을 무선으로 전송하여 빔프로젝터로 전달하는 저비용 실시간 시스템을 설계 및 구현하는 것을 목표로 한다. 본 시스템의 기능은, 컴퓨터영상 정보의 획득, 영상정보의 압축, 압축된 정보의 실시간 송수신, 압축해제 및 영상 정보복원, 영상데이터의 외부출력으로 구성된다. 영상 전송의 속도를 최대로 높이기 위하여 무선 전송은 IEEE 802.11g를 사용하고, 전송 데이터의 크기를 줄이기 위하여 표준 정지영상 압축 정보의 생성과 정보 표시 형식을 변형하여 사용한다. 변형된 정지영상 압축방식을 사용한 결과 압축을 하지 않고 전송한 경우에 비해서 약 4배가 빨라졌으며, 한 프레임의 영상을 전송하는데 평균 600ms가량 소요되었다. 이는 일반적 강의에서 사용하는 화면전환 속도로 합리적이라고 볼 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.917-922
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• 2016

Recently, energy harvesting, in which energy is collected from RF signals, has been regarded as a promising technology to improve the lifetime of sensors by alleviating the lack of power supply problem. In this paper, we try to propose an efficient algorithm for simultaneous wireless information and power transfer. At first, we find the lower bound of water-level using the probability density function of channel, and derive the solution of power allocation in energy harvesting networks. In addition, we derive an efficient power splitting method for satisfying the minimum required harvested energy constraint. The simulation results confirm that the proposed scheme improves the average data rate while guaranteeing the minimum required harvested energy constraint, compared with the conventional scheme. In addition, the proposed algorithm can reduce the computational complexity remarkably with insignificant performance degradation less than 10%, compared to the optimal solution.

• Journal of Internet Computing and Services
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• v.13 no.3
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• pp.1-16
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• 2012

Cost-effective mobility management for the roaming mobile users is very important in the seamless services on next-generation wireless network (NGWN). MIPv6 (Mobile IPv6) is one of the mobility management schemes proposed by the IETF (The Internet Engineering Task Force) and various IPv6-based mobility management schemes have been developed. They are directly involved with data transfer from MN (Mobile Node). In this paper, two kinds of schemes in analyzing of mobility management schemes are proposed. The signaling transfer and packet delivery procedures for each mobility management schemes are analyzed, respectively. The signaling cost for mobility management schemes are calculated, and the cost of each protocol are analyzed numerically. In other word, applying the sum of signaling cost and packet delivery cost to each mobility management scheme, their costs are analyzed. Finally, our performance evaluation results that the network-based mobility management scheme shows better performance in terms of overall cost.

• Journal of Korea Multimedia Society
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• v.7 no.2
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• pp.211-222
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• 2004

By development of wireless mobile communication, many users increased. But, in case of 1st generation or 2nd generation, transfer communication service was not satisfying high speed wireless internet Communication consumer's request such as other multimedia service because serviced based on voice and text basically. Can get through service such as data and transfer multimedia service that is not service of voice putting first in wireless hereafter. Problems by much development of service are happening, because a transmit is exposed, problem point that wireless network is much unlawful stealing use and tapping etc. As is different from this, problem can happen in service side. Can take next time for these example. By user that is not right can happen. Need method to keep away purpose that is enemy of third party in contract between both men as well as problem for document or accounting information which the third user that is enemy of third party is shared. By solution about problems, certification of contents for document and visual point confirmation must it. Applied service or certification of contents service that is rapidly point of time that is using in wire to solve problem that refer in front in this treatise in IMT-2000 to develop hereafter. Way to propose proposed efficient way using individual in IMT-2000 just as it is.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3B
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• pp.260-267
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• 2011

Wireless Local Area Network (WLAN) is recently become popular on the internet since we can download and transfer mass data through it. However, transferring data with distances over 100m often causes some troubles. When downloading mass data from moving vehicles such as cars, jeeps, tanks, etc., if the download process from the first AP (Access Point) is not completed then we have to re-start this process from the second AP (from 0%). Therefore, the question is how to maintain the data we have received from the first AP, and then continuously download remaining data from the next APs in a battlefield environment. In this paper, we propose an effective method for receiving mass data separately from the mobile receive nodes in a Delay Tolerant Network (DTN). We carried on an experiment and evaluation by simulation; these simulation results are provided to show the proposed information delivery scheme performance.

• Journal of Information Technology Services
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• v.13 no.4
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• pp.245-254
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• 2014

Payment system is defined as the various contracts and operating facilities for the transfer of monetary value to clear the relationship between credit and debt. Payment systems essentially require the efficient and reliable operations. Card-based payment systems are developed practically and creatively in accordance with the progress of ICT. Especially in mobile environment with intelligent mobile devices such as smart-phones and tablets, a variety of payment services are provided. Existing card-based payment services are configured by the payment transaction initiated by the merchants card acceptance and then swiping into the CAT (Card Authorization Terminal) to begin the transaction. The merchant initiated payment services are now applied to the Wireless CAT (W-CAT) for mobile environment. That kind of payment services cause many problems such the illegal card information leaks and the lingering threat of W-CAT theft. Also, the use of many W-CATs increased cost to the merchant. In this paper, we propose the card holder initiated card payment system using the intelligent mobile devices in mobile environment for solving problems of the existing merchant initiated card payment system and coping effectively with the activation of a wireless data network and changes of information technology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2167-2173
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• 2013

Recently, people are paying huge attention to problems caused by indoor air pollution. Also, the need for the system that monitors environmental information for indoor and warns a danger is growing increasingly. In this regard, we designed and implemented environment monitoring system for indoor. In this paper, we describe the system with hardware elements and it's communication method. In order to transfer the data from environment sensors, we use short-range wireless communication in smart phone. The proposed system is possible to know the indoor environment information in installed sensor node. If the risk is found, For the proposed system, there is an advantage that may be appropriate evacuation.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.219-226
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• 2013

Against the global eavesdropping in wireless sensor networks, tremendous amount of dummy packets for faking are likely to be continuously generated in order to keep the location privacy of the communication source and destination. In our approach only certain disk-shaped zones of encompassing sources and destination are allowed to issue dummy packets during the data transfer so that the amount of generated packets is reduced while the location privacy of the source and destination remains secret. To this end we design a routing protocol and propose a detailed formal specification of it, and verify major characteristics.