• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.15-21
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• 2011

Cooperative diversity system can be applied to an ad-hoc network for reduction of the power consumption, for expansion of the communication range, and for improving the system performance. In a selection relay cooperative diversity system which selects the maximal SNR(Signal-to-noise ratio) relay for transmitting the source information, the selected strong relay transmits continuously under slow fading channel, consequently it reduces the network lifetime. To overcome this defect, recently the uniform power relay selection has been studied to expand the network life time. We apply the uniform power relay selection to a DOT(Double opportunistic transmit) cooperative system that select the transmit relays, of which the SNR of the transmit relays exceed both of the source-relay and the relay-destination threshold. And the performance of the system is analytically derived. The performance comparisons are made among SC(Selection combining), MRC(Maximal ratio combining), and uniform power relay selection of the cooperative diversity system. We noticed that the performance of the uniform power relay selection is inferior to that of others. It is interpreted that the uniform transmit opportunity to the selected relays for extension of the network lifetime degrades the performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3A
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• pp.290-296
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• 2007

We propose new routing scheme, Cooperative Diversity-based Routing (CDR) which utilizes the cooperative space diversity for power saving and performance enhancement of wireless ad-hoc networks. The improved performance is compared with Multi-hop Relay Routing (NRR) by analytical methods. When the required outage probability is $1\times10^{-3}$ at the destination node in ad-hoc networks with 7 nodes, we noticed that each node can save power consumption by 15.5 dB in average, by using our proposed CDR compared to MRR.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2095-2110
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• 2015

This paper presents a design for a throughput-efficient online relay selection scheme for dual-hop multi-relay cooperative networks. Problems arise with these networks due to unpredictability of the relaying link quality and high time-consumption to probe the dual-hop link. In this paper, we firstly propose a novel probing and relaying protocol, which greatly reduces the overhead of the dual-hop link estimation by leveraging the wireless broadcasting nature of the network. We then formulate an opportunistic relay selection process for the online decision-making, which uses a tradeoff between obtaining more link information to establish better cooperative relaying and minimizing the time cost for dual-hop link estimation to achieve higher throughput. Dynamic programming is used to construct the throughput-optimal control policy for a typically heterogeneous Rayleigh fading environment, and determines which relay to probe and when to transmit the data. Additionally, we extend the main results to mixed Rayleigh/Rician link scenarios, i.e., where one side of the relaying link experiences Rayleigh fading while the other has Rician distribution. Numerical results validate the effectiveness and superiority of our proposed relaying scheme, e.g., it achieves at least 107% throughput gain compared with the state of the art solution.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.270-275
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• 2010

In a conventional opportunistic transmit (COT) cooperative relaying system, only the relays that receive signal-to-noise ratio (SNR) from the source and that exceed the threshold transmit to the destination. The COT system, however, only considers the SNR of the source-relay (S-R) path regardless that the SNR of the relay-destination (R-D) path is the opportunistic transmission condition. For that reason, it is not guaranteed that all the transmitted signals from relays exceed the threshold at the destination. Therefore we propose a double opportunistic transmit (DOT) cooperative relaying system - when both of the received SNR from a source and from a destination exceed the threshold, the relay transmits to the destination. It is shown that the proposed DOT system reduces power consumption by 6.9, 20.9, 32.4, and 41.4 % for K =3, 5, 7, and 9, respectively under the given condition of $P_{out}=1{\times}10^{-3}$ and $\overline{\gamma}_{SR}/\Gamma_{SR}$=30 dB, compared to the COT system. We noticed that the performance of the DOT system is superior to that of the COT system for the identical number of active transmit relays under the same condition of the normalized average SNR of $\overline{\gamma}_{RD}/\Gamma_{RD}$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.7
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• pp.372-379
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• 2014

When a hand-held device with limited battery transmits and receives data using short-range wireless communication systems, such as WLAN(Wireless Local Area Network) or high speed WPAN(Wireless Personal Area Network), instead of mobile communication systems, the device is able to reduce the power consumption due to the reduced transmission distance. However, if there are many WLAN or high speed WPAN systems around the device, non-negligible power may be consumed by receiving and decoding the packets which have nothing to do with the device. In this paper, we propose a scheme reducing the power consumption by including physical-layer ID in WLAN or WPAN packets and avoiding unnecessary packet receptions. Also, we describe a method to determine the optimum number of physical-layer IDs.

• Korean Journal of Organic Agriculture
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• v.28 no.3
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• pp.367-386
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• 2020

The significance of this study was to analyze the quality value of organic livestock pork for the first time based on the results of managing and testing the cycling organic farming of black pork and vegetables within farm for two years. The results of analysis could be summarized as follows. First, the pork of experimental group with crop-livestock cycling farming showed the excellent quality and high consumer preference compared to the control group of general pork or pork from non-crop-livestock cycling organic farming. In the content ratio of Omega-3 as a representative essential fatty acid, it was 1.46 that was about 2.8 times more than general pork (0.52). In case of Omega-6, it had about 2.5 times more than general pork. Especially, the U/S ratio value which was the content ratio of Unsaturated Fatty Acid (UFA, U) of Saturated Fatty Acid (SFA, S), was largely shown in pork (2.93) from cycling organic farming. Second, it would be necessary to maintain the economies of scope shown in crop-livestock cycling organic farming, and the high quality value of livestock products. For this, there should be a value chain model that could realize the economies of scope and economies of scale at the same time based on scaling and diversification through cooperative organization between farmers. Through this, it would be possible to establish a cycling model called 'community cooperative agriculture' by forming local internal markets through cooperation of production-processing and integration of distribution-sale-consumption. For the managerial activation of this cooperative organization, the government should promote/support the small crop-livestock cycling organic farming cooperative organization in local unit. For securing the reliability of crop-livestock cycling organic agricultural products and crop-livestock cycling organic livestock products, it would be necessary to review the introduction of Participatory Guarantee System (PGS).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.8
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• pp.985-994
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• 2012

This paper presents the real channel measurements and investigates their statistical characterization in wireless body area network(WBAN). In on-/off body channel, the measurements are performed with some representative human movements for considering human movements. Moreover, three signal transmission schemes with outage constraint are studied for getting total power consumption in each transmission scheme. Using the real channel measurements, between theoretical and realistic simulation are compared. This paper shows that power efficiency is improved through cooperative communication, and how much position of sensor node and human movement affect signal transmission power.

• KDI Journal of Economic Policy
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• v.39 no.3
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• pp.19-41
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• 2017

This paper examines the aspects of changes in China's consumer market since the mid-1980s. By comparing urban and rural residents' expenditures, I find that the rural consumer market has exhibited extraordinary growth. Over the past decade, the consumption growth rate and average propensity to consume by rural residents have surpassed those of their urban counterparts, with the former's consumption patterns becoming increasingly similar to the latter's. Such a phenomenon prevails in rural areas which neighbor second-and third-tier cities where urbanization is progressing rapidly. These findings imply that Korean companies need to diversify their export goods in line with China's expanding rural markets while further differentiating their product composition to satisfy the heterogeneous demands in urban areas. With regard to the government, efforts must be made to strengthen the export cooperative system so that it targets not only urban but also rural markets in China.

• ETRI Journal
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• v.42 no.3
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• pp.341-350
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• 2020

In a wireless sensor network (WSN), the data transmission technique based on the cooperative multiple-input multiple-output (CMIMO) scheme reduces the energy consumption of sensor nodes quite effectively by utilizing the space-time block coding scheme. However, in networks with high node density, the scheme is ineffective due to the high degree of correlated data. Therefore, to enhance the energy efficiency in high node density WSNs, we implemented the distributed source coding (DSC) with the virtual multiple-input multiple-output (MIMO) data transmission technique in the WSNs. The DSC-MIMO first compresses redundant source data using the DSC and then sends it to a virtual MIMO link. The results reveal that, in the DSC-MIMO scheme, energy consumption is lower than that in the CMIMO technique; it is also lower in the DSC single-input single-output (SISO) scheme, compared to that in the SISO technique at various code rates, compression rates, and training overhead factors. The results also indicate that the energy consumption per bit is directly proportional to the velocity and training overhead factor in all the energy saving schemes.

• Food Science of Animal Resources
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• v.21 no.2
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• pp.110-115
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• 2001

The major objective of this study is provide to basic data for developing of new chicken products. The findings from this study are as follow. Eating times of chicken is increased in comparison with National Livestock Cooperative Federation(NLCF) & Korea Chicken Council(KCC)s survey results. Consumers are frequently having fried chicken and this results are no difference in KCCs survey results. In eating place of chicken, consumers are mostly preferred to have chicken at home. In the use of chicken consumption, the ratio of replacing meal is high and this is no difference in previous study. However there are a few differences in consumption behavior by age and gender.