• Journal of IKEEE
• /
• v.21 no.3
• /
• pp.284-287
• /
• 2017

In this study, we examined the simulated electrical characteristics of single-gated feedback field effect transistors (FBFETs) and the influence of channel length variation of the memory window characteristics through the 3D device simulation. The simulations were carried out for various channel lengths from 50 nm to 100 nm. The FBFETs exhibited zero SS(< 1 mV/dec) and a current $I_{on}/I_{off}$ ratio${\sim}1.27{\times}10^{10}$. In addition, the memory windows were 0.31 V for 50 nm-channel-length devices while no memory windows were observed for 100 nm-channel-length devices.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.8
• /
• pp.72-79
• /
• 1994

In this paper semi empirical models are presented for the hot electron induced threshold voltage shift(${\Delta}V_{t}$) and effective channel shortening length (${\Delta}L_{H}$) in degraded PMOSFET. Trapped electron charges in gate oxide are calculated from the well known gate current model and ΔLS1HT is calculated by using trapped electron charges. (${\Delta}L_{H}$) is a function of gate stress voltage such as threshold voltage shift and degradation of drain current. From the correlation between (${\Delta}L_{H}$) has a logarithmic function of stress time. From the measured results, (${\Delta}V_{t}$) and (${\Delta}L_{H}$) are function of initial gate current and device channel length.

• Journal of Communications and Networks
• /
• v.14 no.2
• /
• pp.121-129
• /
• 2012

In this paper, we consider a source node that operates over a time varying channel with energy harvesting capability. The goal of the source is to maximize the average number of successfully delivered packets per time slot. The source is able to choose whether to transmit a packet or defer the transmission in each time slot. The decision which is chosen by the source depends on the channel information available and the length of the energy queue. We formulate the problem of finding the optimal policy as a Markovian decision problem. We show some properties of the value function that represents the discounted number of successfully delivered packets per time slot. We prove that the optimal policy is a threshold type policy depending on the state of the channel and the length of the energy queue. We also derive an upper bound for the average number of packets per time slots successfully received by the destination. We show using numerical results that this bound is a tight bound on the performance of the optimal policy. And we consider the case of time varying channel but without channel state information (CSI). Then, we study the impact of channel time varying nature and the availability of CSI. In this case, we show that the optimal policy is a greedy policy. The performance of this greedy policy is also calculated.

• Electrical & Electronic Materials
• /
• v.8 no.6
• /
• pp.708-714
• /
• 1995

We have discussed the buried-channel(BC) behavior through the subthreshold characteristics of submicron PMOSFET device fabricated with twin well CMOS process. In this paper, we have guessed the initial conditions of ion implantation using process simulation, obtained the subthreshold characteristics as a function of process parameter variation such as threshold adjusting ion implant dose($D_c$), channel length(L), gate oxide thickness($T_ox$) and junction depth of source/drain($X_j$) using device simulation. The buried channel behavior with these process prarameter variation were showed apparent difference. Also, the fabricated pMOSFET device having different channel length represented good S.S value and low leakage current with increasing drain voltage.

• ETRI Journal
• /
• v.45 no.6
• /
• pp.952-962
• /
• 2023

In this study, a space-time transmission scheme is proposed to tackle the limitations of channel estimation with orthogonal pilot information in colocated multiple-input multiple-output systems with several transmitting and receiving antennas. Channel information is obtained using orthogonal pilots. Channel estimation introduces pilot heads required to estimate a channel. This leads to bandwidth insufficiency. As a result, trade-offs exist between the number of pilots required to estimate a channel versus spectral efficiency. The detection of data symbols is performed using the maximum likelihood decoding method as it provides a consistent approach to parameter estimation problems. The moment-generating function of the instantaneous signal-to-noise ratio is used to drive an approximate expression of the symbol error rate for the proposed scheme. Furthermore, the order of diversity is less by one than the number of receiver antennas used in the proposed scheme. The effect of the length of a pilot sequence on the proposed scheme's performance is also investigated.

• Journal of information and communication convergence engineering
• /
• v.3 no.1
• /
• pp.1-4
• /
• 2005

This study proposes a new diversity algorithm to improve the signal-to-noise ratio. In the wireless channel, if fading occurs due to the multipaths, the performance of the system is apparently reduced. One of the methods to reduce fadings like this is the diversity method, and this study aims to improve the performance of the system by proposing a new diversity algorithm. This study applied rake receiver, and normalized the wireless channel from the Nakagami fading channel to the Rayleigh fading channel, which set the fading index as 1, because of the multipaths. It applied QPSK and OQPSK modulation methods and applied the convolutional codes, where the code rate is 1/2 and 1/3 and the constraint length is 9, and the turbo code where the constraint length is 4. Under these conditions, this study compared and analyzed the average error probability of direct spread multiple access system. The diversity algorithm proposed in this paper could be applied to the mobile communication and other wireless multimedia communications that require high quality and high reliability.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.9
• /
• pp.863-871
• /
• 2004

In this paper, we propose a subspace channel estimation technique for DS/CDMA DMB down link system, which can obtain reduction in numerical complexity by using of matched filtering outputs. The complexity reduction is considerable when the channel length is small and the system is moderately loaded. Previously proposed subspace-based blind channel estimation algorithm suffer from high numerical complexity for systems with large spreading gains. Although the proposed algerian suffers a slight performance loss, it becomes negligible for large observation length. Performance is evaluated through simulations and the derivation of the analytical MSE.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.4 no.4 s.15
• /
• pp.13-19
• /
• 2004

The tremendous flood damage caused by Typhoon Rusa(2002) was occurred at GangNeung City in GangWon Province. Almost of the city region was inundated and most of the stream channel facilities were damaged by flash flood with heavy rainfalls. We have investigated seriously damaged parts of stream bank and tried to analyze the causes of damages focused on flow characteristics in curved channel. We analyzed the damage aspects of curved channel by examining geomorphological survey and hydrographical characteristics. Strong correlation was shown according to the regression analysis between length of stream and meander wave length, and meander belt and length of stream. Furthermore, enveloped curve was presented between bottom slope of channel and meander belt, and meander ratio and channel width. As a result, special consideration about stream flow characteristics are needed for engineers who design stream banks and channels.

• KCID journal
• /
• v.21 no.1
• /
• pp.118-126
• /
• 2014

In this study, the use of the spur of riverbank technique is being investigated. The spur of the riverbank typically reduces the velocity of flow and protects the embankments by increasing friction along the water and the banks. This also has an effect in the rise of water level upstream. It is also used for the rectification of riverside line and restoration of the waterway through sedimentation near the spur of the riverbank. In this study, physical-scaled experiments are conducted to investigate the process of creating a mild meandering channel using the spur of the riverbank with varying water flows and sedimentation functions. The hydraulics observations are taken with respect to the varying heights and length of the riverbank's spurs and the distance between each spur for the formation of the mild meandering channel. It is observed that for 1.06 times of the meander length, it requires 2 times of the interval with each spur of river width. Similarly, 1.25L times of the meander length, it requires 0.5 times of the interval with each spur of river width. The sand accumulation is induced by the spur of riverbank when the spur of riverbank's heights are more than 40% of water depth and the length of the spur of riverbank needs under than 20% of river width for avoid exaggerated sand accumulation in the center of channel.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.1189-1192
• /
• 2009

Short channel a-Si:H TFT devices with Cu electrodes have been investigated. Short channel TFTs are defined by new plasma etch process. When the channel length becomes shorter, the TFT characteristics (threshold voltage, off current, sub threshold voltage, etc.,) are degraded. These degraded characteristics can be improved through the hydrogen plasma treatment and new gate insulator structure. Using these processes, 15.0 inch XGA LCD panel was fabricated successfully where the channel length of the TFT devices was about 2.5 micrometers.