• Journal of information and communication convergence engineering
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• 제9권3호
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• pp.310-314
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• 2011

This paper has presented doping profile dependent threshold voltage for DGMOSFET using analytical transport model based on Gaussian function. Two dimensional analytical transport model has been derived from Poisson's equation for symmetrical Double Gate MOSFETs(DGMOSFETs). Threshold voltage roll-off is very important short channel effects(SCEs) for nano structures since it determines turn on/off of MOSFETs. Threshold voltage has to be constant with decrease of channel length, but it shows roll-off due to SCEs. This analytical transport model is used to obtain the dependence of threshold voltage on channel doping profile for DGMOSFET profiles. Also we have analyzed threshold voltage for structure of channel such as channel length and gate oxide thickness.

• 한국통신학회논문지
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• 제17권11호
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• pp.1290-1298
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• 1992

본 논문은 fitting 파라미터를 배제하고 2차원적 Poisson 방정식을 도출해서 short-channel MOSFET의 model 식을 완전히 해석적으로 성립시켰다. 이로 인해 포화영역, 문턱전압, 강반전에 대한 것이 동시에 표현되는 정확한 드레인 전류가 유도되었다. 더욱이 이 model은 short-channel과 body효과, DIBL효과, 그리고 carrier운동에 대한 것도 설명할 수 있으며 온도와 $n^+$접합, 산화층에 관련되는 문턱전압도 표현할 수 있었다.

• Journal of Communications and Networks
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• 제5권2호
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• pp.157-166
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• 2003

This paper deals with the problem of channel identification for Single Input Multiple Output (SIMO) slow fading channels using clustering algorithms. Due to the intrinsic memory of the discrete-time model of the channel, over short observation periods, the received data vectors of the SIMO model are spread in clusters because of the AWGN noise. Each cluster is practically centered around the ideal channel output labels without noise and the noisy received vectors are distributed according to a multivariate Gaussian distribution. Starting from the Markov SIMO channel model, simultaneous maximum ikelihood estimation of the input vector and the channel coefficients reduce to one of obtaining the values of this pair that minimizes the sum of the Euclidean norms between the received and the estimated output vectors. Viterbi algorithm can be used for this purpose provided the trellis diagram of the Markov model can be labeled with the noiseless channel outputs. The problem of identification of the ideal channel outputs, which is the focus of this paper, is then equivalent to designing a Vector Quantizer (VQ) from a training set corresponding to the observed noisy channel outputs. The Linde-Buzo-Gray (LBG)-type clustering algorithms [1] could be used to obtain the noiseless channel output labels from the noisy received vectors. One problem with the use of such algorithms for blind time-varying channel identification is the codebook initialization. This paper looks at two critical issues with regards to the use of VQ for channel identification. The first has to deal with the applicability of this technique in general; we present theoretical results for the conditions under which the technique may be applicable. The second aims at overcoming the codebook initialization problem by proposing a novel approach which attempts to make the first phase of the channel estimation faster than the classical codebook initialization methods. Sample simulation results are provided confirming the effectiveness of the proposed initialization technique.

• 한국농공학회논문집
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• 제61권4호
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• pp.33-42
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• 2019

In this study, the channel and floodplain widths are indirectly measured for three different watersheds using satellite images to reflect the shape of Korean channels in the Soil and Water Assessment Tool (SWAT) model. For measuring the channel and floodplain widths, multiple satellite images were referred to ensure the widest width of certain points. In the single channel, the widths at the multiple points were measured. Based on the measured data, the regression equations were derived to estimate the channel and floodplain widths according to watershed areas. Applying these developed equations, this study evaluated the effect of the change of channel and floodplain widths on the SWAT simulation by comparing to the measured streamflow data. The developed equations estimated larger channel width and smaller floodplain compared with those calculated in the current SWAT model. As shown in the results, there was no considerable changes in the predicted streamflow using the current and developed equations. However, the flow velocity and channel depth calculated from the developed equations were smaller than those of the current equations. The differences were caused by the effect of different channel geometries used for calculating the hydraulic characteristics. The channel geometries also affected the water quality simulation in channels because the hydraulic characteristics calculated by the channel geometries are directly related to the water quality simulation. Therefore, application of the river cross-sectional regression equation reflecting the domestic stream shape is necessary for accurate water quantity / quality and water ecosystem simulation using hydrological model.

• 한국통신학회논문지
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• 제23권4호
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• pp.1113-1120
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• 1998

This paper introduces a channel model that is a combination of Rice and log-normal statistics, with independent shadowing affectingeach direct and diffuse component, repectively. This model extends the channel model of a combined Rice and Log-normal, proposed by Corazza, to include the independent shadowing. The validity of model is confirmed by comparisons with the data collectedin the literature, the analytical model, and the computer model in terms of probability distribution of the evvelope of each model. The model turns out to be one of many well-known narrowband models in limiting cases, e.g. Rayleigh, Rice, log-normal, Suzuki, Loo, and Corazza. Finally, the examples of bit error probability evaluations for several values of the elevation angle in the channel are provided.

• 천문학회보
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• 제46권1호
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• pp.42.2-43
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• 2021

We address a question of what are three main channels that can best translate other channels in ultraviolet (UV) and extreme UV (EUV) observations. For this, we compare the image translations among the nine channels of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory using a deep learning model based on conditional generative adversarial networks. In this study, we develop 170 deep learning models: 72 models for single-channel input, 56 models for double-channel input, and 42 models for triple-channel input. All models have a single-channel output. Then we evaluate the model results by pixel-to-pixel correlation coefficients (CCs) within the solar disk. Major results from this study are as follows. First, the model with 131 Å shows the best performance (average CC = 0.84) among single-channel models. Second, the model with 131 and 1600 Å shows the best translation (average CC = 0.95) among double-channel models. Third, among the triple-channel models with the highest average CC (0.97), the model with 131, 1600, and 304 Å is suggested in that the minimum CC (0.96) is the highest. Interestingly they are representative coronal, photospheric, and chromospheric lines, respectively. Our results may be used as a secondary perspective in addition to primary scientific purposes in selecting a few channels of an UV/EUV imaging instrument for future solar satellite missions.

• 한국통신학회논문지
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• 제38C권3호
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• pp.288-295
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• 2013

본 논문에서는 4S (Ship to Ship, Ship to Shore) 해상통신을 위해 다른 채널 조건 하에서 기존의 채널 추정 기법을 비교하였다. 일반적으로 수신 신호는 다중경로나 부호 간 간섭에 의해 손상을 받게 된다. 시간 변화 다중 페이딩 채널의 추정은 수신기에서 어려운 작업이며, 적절한 채널 추정 필터를 사용함으로써 수신기의 성능을 향상시킬 수 있다. 모의실험은 MATLAB을 사용하여 AWGN (Additive White Gaussian Noise), Rician, Rayleigh 채널에서 채널 추정 알고리즘으로 주로 사용되어지는 LMS (Least Mean Square)와 RLS (Recursive Least-Squares) 알고리즘을 비교 하였다.

• Human Ecology Research
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• 제54권4호
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• pp.405-414
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• 2016

The rapid change of consumer expectations in shopping environments has required retailers to actively adopt omni-channel services, however, limited research exists on the topic. We identify the effect of consumer's utilitarian shopping value on expectations for omni-channel services. An online survey was conducted on 176 subjects who had experience using omni-channel services. We employed Unified Theory of Acceptance and Use of Technology (UTAUT) as our theoretical model to explore the mechanisms of consumers' acceptance of omni-channel services in fashion. We used SPSS ver. 22.0 and AMOS ver. 22.0 programs to analyze data. The results indicate that utilitarian shopping value has a positive effect on performance expectancy, effort expectancy, and social influence for omni-channel services. Performance expectancy for omni-channel services also has a positive effect on the purchase intentions of fashion products. Effort expectancy for omni-channel services also positively increases the purchase intentions of fashion products. Last, the social effect of omni-channel services has a significant positive effect on purchase intention. All the hypotheses were supported. The research findings can provide the fashion distribution industry with useful basic data to understand the needs of consumers who use multi-channels when establishing a new channel or marketing strategy.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권2호
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• pp.107-111
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• 2003

In the power-line communication systems, there are many factors of noise and attenuation in the power-line channels, because they were designed for not the communication but the power transmission. Also the transfer function of the channels is highly changed with the topology and the load of the power-lines. To cope with these poor channel situation, channel modeling, one of the many studies in progress, is being studied hard. Channel modeling is essential to apply the active schemes to overcome the bad channel(e.g. modulation technique, channel coding, signal coupling & filtering, etc.) to the power-line communications. In this paper, we have realized the statistical model(this model is suggested as the channel modeling method for the power-line channels) that is combined the transfer function with the various noises. And we have compared and examined the results with the measured data. Also we have studied the plan which can effectively establish the channel data base for the channel information consisted of the parameters that are derived from this modeling, and we have studied the plan to utilize the data base.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.305-308
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• 2001

We analyze mathematically a VSB (vestigial side-band) transceiver system for the Advanced Television Systems Committee (ATSC) digital television standard and extract a near-baseband equivalent VSB channel model. This model shows the multi-path fading effect of the quadrature component on the in-phase component. Also, we obtain a simplified model of the VSB transceiver system, which is represented by convolution of the transmission signal (before modulation) and the VSB channel. This simplified model is efficiently used for simulation of VSB systems to improve its performances, especially in an equalization part. Applying the DTV channel specifications tested by the Advanced Television Test Conter (ATTC) to the channel model, we obtain an equivalent VSB channel and show the equalization result by using the conventional derision-feedback equalize (DFE).