• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.6
• /
• pp.69-74
• /
• 2014

In this paper, an energy harvesting scheme is investigated in the multi-relay cooperation communication. Our proposal is to maximize the diversity gain and overcome the disadvantages of the limited power wireless devices. The best relay is selected based on the maximizing channel gains from source to relays so that the harvested energy at selected relay is best. If an internal power of the best relay is lower than a defined target power, the best relay will harvest the energy from the source, and the help of the source-destination link is changed to the second best relay. By this operation method, the diversity gain is maintained and the performance of the network is improved. Finally, performance of the proposed protocol is analyzed in terms of bit error rate, utilization efficiency, power collection efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.8A
• /
• pp.610-617
• /
• 2009

This paper proposes a cross-layer design combining adaptive modulation and coding (AMC) with truncated hybrid automatic repeat request (HARQ) for wireless multicast transmission, in order to increase the spectral efficiency while meeting the target quality-of-service (QoS). In the design, we provide the selection criterion of AMC so as to satisfy the target packet error rate (PER) of all users when the multicast data is received through the common channel and the number of retransmission is limited by the delay constraint of the service. The analytically derived results show that the cross-layer design using HARQ provides a better spectral efficiency than the AMC without HARQ by allowing retransmission and code combining. It is also observed that the design for multicast outperforms that for unicast in the mid to high signal-to-noise ratio region.

• Korean Journal of Health Education and Promotion
• /
• v.20 no.3
• /
• pp.125-143
• /
• 2003

With the shift of cause of death from infection to chronic, the health expenditure has risen dramatically. To curb the increasing health expenditure, programs and campaigns to promote health were proposed and implemented. Most of them, however, were not successful in achieving satisfactory results. Customer Relationship Management has been gradually accepted as an innovative approach to health promotion. The objective of this research was to develop a Customer Relationship Management system for providing comprehensive health care services to the residents in the community. Detailed objectives were as follows： The first objective was the development of the CRM system for health promotion. The second objective was the satisfaction assessment for the health promotion program using the CRM system. The third was the proposal for the effective utilization of the CRM system. The development methodology of the CRM system was Rapid Warehouse Developing Method. As a CRM system equipment, a workstation with GIS of Windows 2000 was selected. SQL Server 2000 was used as a development tool and database. The subjects of study were diabetic mellitus patients, hypertension patients, and vaccin patients. The campaign channel of patients was an autocalling system. For the satisfaction assessment, a survey was performed. The main content of the survey was satisfaction level. The satisfaction level of the health promotion program using CRM system was 79.3%. In consideration of the above findings, we suggested ways of improving the Health Promotion Program by using CRM. The first was the efficient selection of the subjects of the Health Promotion Program. The second was the development for health promotion program using CRM system(life time health of individual etc).

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.8
• /
• pp.651-659
• /
• 2014

In this paper, we consider a two way relay network for ship-to-ship communications in a fleet, where two communicating ships exchange the information with the help of a multi-antenna relay ship. For the network, we propose a rate-aware three-phase analog network coding to improve the reliability of the information exchange with asymmetric rates. The proposed scheme allows low-complex implementation of the relay without channel estimation by generating an improved analog network coded signal with the orthogonally received signals from two ships by using only the received signal power at each antenna. In addition, the proposed scheme reduces outages in the data exchange at asymmetric rates by adopting a rate-aware relay power allocation, which is confirmed by evaluating the outage performance via simulation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.3 s.94
• /
• pp.277-285
• /
• 2005

In this paper, we propose the occupied bandwidth(OBW) measurement method for effectively measuring the 99 $\%$ OBW at monitoring station. In order to validate the measurement results obtained from the proposed measurement method, the modified adjacent channel power ratio(MACPR) is herein defined as the formula which was suitable for applying to the OBW measurement of 8-VSB DTV signals. It has been found that the MACPR is a good measurement parameter applicable for the proper site selection of monitoring station and the effective OBW measurement of 8-VSB DTV signals should be made for MACPR$\geq$35 dB with 600 measurement trials. The proposed measurement procedure is herein given and proven to effectively be applicable to the OBW measurement of terrestrial 8-VSB DTV signals on the air.

• Proceedings of the Korea Society of Information Technology Applications Conference
• /
• 2002.11a
• /
• pp.407-411
• /
• 2002

Ternary sequences are digital codes consisting of discrete values -1, 0, and 1 only. They are advantageous in that the correlation can be carried out using additions only. Also, they feature an ideal circular autocorrelation function, but in channel characterization tasks, the usual requirement is that the linear autocorrelation function be ideal, i.e., a Kronecker delta function. In this article, we consider two approaches to improving their linear autocorrelation or crosscorrelation properties: one is an inverse filtering method with thresholding, and the other is a singular value decomposition (SVD) method. Both methods are simulated under noisy circumstances. The inverse filtering method resulted in an improvement in peak sidelobe level of about 11 dB at an SNR of 30 dB, and the SVD method showed similar performances, albeit more sensitive to noise depending on the singular value selection strategy.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.6
• /
• pp.1-8
• /
• 1998

This paper presents an asynchronous DS/CDMA multiuser detector, which is a two stage, symbol-by-symbol scheme consisting of conventional detectors followed by linear decorrelating detectors. The conventional detector first makes temporal decisions and the detected symbols are delayed by one symbol period to be used for the selection of decorrelating bases in the subsequent decorrelaing detection stage. It also employs a bank of early-late correlators in place of a bank of single correlators taking the small offset of chip timing asynchronism into account. The proposed detector requires only the coarse knowledge of relative time delays of interfering users and is suitable for digital implementation. To verify the detector performance, the analytical BER performance will be given and compared with the simulation results for BPSK DS/CDMA signals in AWGN channel. While the performance of the proposed detector will be analyzed for time-limited signal, the simulation is carried out for both the time-limited and band-limited signals. As can be seen in the simulation results, the proposed scheme shows good results.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.2 no.2 s.3
• /
• pp.1-12
• /
• 2003

DAB(Digital audio broadcasting) is a next generation radio broadcasting system which provides CD quality audio, various data services and superior reception ability when moving. Also, it can show traffic informations and news literally or graphically. In this paper, we design and fabricate the DAB tuner for ITS service that follows Eureka-147 and ETSI 300 401 specifications. This small-sized tuner can be adopted to mny electronic equipments such as a Hi-Fi audio, DVD player, car audio system etc.. The overall performance of the tuner depends on a phase noise of VCO and the sensitivity of the receiving system is influenced by LNA, image rejection filter and channel selection filter. All our measurement results satisfy the specification for a DAB system with the return loss of 9dB, the noise figure of 6dB for both Band 111 and L-band and the sensitivity of -97dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.9
• /
• pp.965-970
• /
• 2010

Because of a large number of subcarriers, the high PAPR(Peak-to-Average Power Ratio) is the major drawback of NC-OFDM system used for wireless communication system. Comb type pilot assignment is more efficient and lower computational complexity for the channel estimation than the block type pilot. However, even if the CAZAC(Constant Amplitude Zero Autocorrelation) matrix transform is used for the PAPR reduction of the data symbols, PAPR increases when the pilot is inserted in comb type with the data symbols. Therefore, in this paper, we additionally use a new SLM technique in order to lower the PAPR again even in the comb type pilot. Also, a new SLM technique suggested in this paper does not need any additional bandwidth for sending selection information for SLM. This combined method has good PAPR reduction performance and efficient data transmission.

• The Journal of Information Technology
• /
• v.5 no.1
• /
• pp.157-171
• /
• 2002

The evolution of transaction-based business model is upon us. The business models of many e-Marketplace in their early stages have typically been based on transaction fees. Many e-Marketplaces have even called out transaction revenues as a core element of their business plans. The transaction business represents the most simple of business models, but it does not provide a long-term sustain able advantage. For buyer's convenience, wide selection and test price hold appeal. For suppliers, the extended global market reach and direct access to customers and consortiums of customers is powerful. To maxmize leverage of these new e-marketplace, you must from both a buyer perspective as well as a supplier perspective. Also required is a strategy that takes in account all of the various e-Marketplace transaction standards and one that allows the easy accomodation to new e-marketplace as the market change. These new e-marketplace will need to be factored into the sales channel strategies. To be successful, integration with these e-marketplaces should occur at a complete business process level. This study explored independent and industry-backed current and future business models that are emerging in the B2B electronic market industry, as well as value -added service models for the Net market maker industry. E-Marketplaces will evolve into digital work environments in which real industry collaboration can occur.