• Journal of Hydrogen and New Energy
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• v.20 no.6
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• pp.479-484
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• 2009

The effect of anode gas channel height on gas diffusion and cell performance in a 100 $cm^2$ class molten carbonate single cell is investigated. Single cell separators with three different channel height are used. The effect of the gas channel height on the distribution of the reactive gas concentration is evaluated by the two-dimensional concentration diffusion equation. The overpotential caused by concentration drop with different channel height is estimated by the voltage decay related to diffusion of reactants, well known as concentration polarization, using limiting current density. The estimation could have the possibility to identify the reactant mass transfer polarization in the complicate factors of the overall electrodes.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.797-803
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• 2002

In this paper we derive the probability density function of the phase error of the received signal over Rician fading channel and verify its propriety as the probability density function using the zeroth moment. In general, for the error probability over fading channel we compute the error probability in the first place when it is only AWGN, and then we get the final result by averaging the first result and the probability density function of the corresponding fading channel. In this paper, however, we compute the error probability by double integration after the probability density function over fading channel is computed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2621-2626
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• 2013

This paper has presented the potential distribution for asymmetric double gate(DG) MOSFET, and sloved Poisson equation to obtain the analytical solution of potential distribution. The symmetric DGMOSFET where both the front and the back gates are tied together is three terminal device and has the same current controllability for front and back gates. Meanwhile the asymmetric DGMOSFET is four terminal device and can separately determine current controllability for front and back gates. To approximate with experimental values, we have used the Gaussian function as doping distribution in Poisson equation. The potential distribution has been observed for gate bias voltage and gate oxide thickness and channel doping concentration of the asymmetric DGMOSFET. As a results, we know potential distribution is greatly changed for gate bias voltage and gate oxide thickness, especially for gate to increase gate oxide thickness. Also the potential distribution for source is changed greater than one of drain with increasing of channel doping concentration.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.691-694
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• 2013

This paper has presented the potential distribution for asymmetric double gate(DG) MOSFET, and sloved Poisson equation to obtain the analytical solution of potential distribution. The symmetric DGMOSFET where both the front and the back gates are tied together is three terminal device and has the same current controllability for front and back gates. Meanwhile the asymmetric DGMOSFET is four terminal device and can separately determine current controllability for front and back gates. To approximate with experimental values, we have used the Gaussian function as charge distribution in Poisson equation. The potential distribution has been observed for gate bias voltage and gate oxide thickness and channel doping concentration of the asymmetric DGMOSFET. As a results, we know potential distribution is greatly changed for gate bias voltage and gate oxide thickness, especially for gate to increase gate oxide thickness. Also the potential distribution for source is changed greater than one of drain with increasing of channel doping concentration.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1311-1316
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• 2016

This paper analyzes the influence of tunneling current on threshold voltage shift by channel length of short channel asymmetric double gate(DG) MOSFET. Tunneling current significantly increases by decrease of channel length in the region of 10 nm below, and the secondary effects such as threshold voltage shift occurs. Threshold voltage shift due to tunneling current is not negligible even in case of asymmetric DGMOSFET to develop for reduction of short channel effects. Off current consists of thermionic and tunneling current, and the ratio of tunneling current is increasing with reduction of channel length. The WKB(Wentzel-Kramers-Brillouin) approximation is used to obtain tunneling current, and potential distribution in channel is hermeneutically derived. As a result, threshold voltage shift due to tunneling current is greatly occurred for decreasing of channel length in short channel asymmetric DGMOSFET. Threshold voltage is changing according to bottom gate voltages, but threshold voltage shifts is nearly constant.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.119-127
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• 2006

In this two-part paper, we consider dynamic resource allocation in orthogonal frequency division multiple access(OFDMA). To reduce the reverse link overhead for channel quality information(CQI) feedback, a set of sub-carriers are tied up to a sub-channel to be used as the unit of CQI feedback, user-multiplexing and the corresponding power/rate allocation. Specifically, we focus on two sub-channel structures, either aggregated or distributed, where the SNR distribution over a sub-channel is modeled as Ricean in general, and the channel quality of a sub-channel is summarized as the mean and variance of channel gain envelop divided by noise standard deviation. Then, we develop a generalized two step channel/resource allocation algorithm, which uses the two statistical measurements, and analyze the spectral efficiency of the OFDMA system in terms of average frequency utilization. An extension to proportional fair algorithm will also be addressed. As confirmed by numerical results, the aggregated structure is preferred especially when intending aggressive link adaptation.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.3
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• pp.393-406
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• 2017

A "Showrooming" phenomenon has emerged due to the rapid growth of the on-line shopping market and is associated with consumer shopping patterns. This phenomenon is resulted in new strategies such as the Omni-Channel strategy that are now being employed by the off-line retail industry to meet the needs of consumers who seek information on-line. In particular, human services provided in department stores (which still occupy an important place in the off-line retail industry) are reaching limitations in the ability to maintain consumers. This study provides basic data for the Omni-Channel strategy of domestic department stores by researching and analyzing Omni-Channel strategy cases in Manhattan. This study dissects and analyzes the "Showrooming" phenomenon and the development of the Omni-Channel strategy through a literature review as well as analyzes the Omni-Channel success case of Macy's department store. The findings indicate that the use of the Omni-Channel strategy by Macy's department store has solved the problem of "Showrooming," by integrating on-line and off-line shopping to provide an efficient and convenient shopping experience for consumers. The Omni-Channel strategy offers a means for off-line stores to connect to the online shopping behavior of consumers. The results suggest the need for an organic combination of on-line and off-line distribution channels to adapt to changes in consumer shopping patterns due to a recession in the domestic market.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2183-2188
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• 2014

This paper has analyzed threshold voltage movement for channel doping concentration of asymmetric double gate(DG) MOSFET. The asymmetric DGMOSFET is generally fabricated with low doping channel and fully depleted under operation. Since impurity scattering is lessened, asymmetric DGMOSFET has the adventage that high speed operation is possible. The threshold voltage movement, one of short channel effects necessarily occurred in fine devices, is investigated for the change of channel doping concentration in asymmetric DGMOSFET. The analytical potential distribution of series form is derived from Possion's equation to obtain threshold voltage. The movement of threshold voltage is investigated for channel doping concentration with parameters of channel length, channel thickness, oxide thickness, and doping profiles. As a result, threshold voltage increases with increase of doping concentration, and that decreases with decrease of channel length. Threshold voltage increases with decrease of channel thickness and bottom gate voltage. Lastly threshold voltage increases with decrease of oxide thickness.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.748-751
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• 2014

This paper has analyzed threshold voltage movement for channel doping concentration of asymmetric double gate(DG) MOSFET. The asymmetric DGMOSFET is generally fabricated with low doping channel and fully depleted under operation. Since impurity scattering is lessened, asymmetric DGMOSFET has the adventage that high speed operation is possible. The threshold voltage movement, one of short channel effects necessarily occurred in fine devices, is investigated for the change of channel doping concentration in asymmetric DGMOSFET. The analytical potential distribution of series form is derived from Possion's equation to obtain threshold voltage. The movement of threshold voltage is investigated for channel doping concentration with parameters of channel length, channel thickness, oxide thickness, and doping profiles. As a result, threshold voltage increases with increase of doping concentration, and that decreases with decrease of channel length. Threshold voltage increases with decrease of channel thickness and bottom gate voltage. Lastly threshold voltage increases with decrease of oxide thickness.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.7-12
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• 2019

Ambient backscatter communication is limited to channel estimation technique through a pilot signal, which is a channel estimation method in current RF communication, due to transmission power efficiency. In a limited transmission power environment, the research of traditional ambient backscatter communication has been studied assuming that it is an ideal channel without signal distortions due to channel conditions. In this paper, we propose an expectation-maximization(EM) algorithm, one of the blind channel estimation techniques, as a channel estimation method in ambient backscatter communication system which is the state of channel following normal distribution. In the proposed system model, the simulations confirm that channel estimate through EM algorithm is approaching the lower bound of the mean square error compared with the Bayesian Cramer-Rao Boundary(BCRB) to check performance. It shows that the channel parameter can be estimated in the ambient backscatter communication system.