• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.267-273
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• 2007

A depletion-mode MOSFET has been analyzed to evaluate its electrical behavior using a novel 3-D numerical simulation package. The characterizing analysis of the BC MOSFET was performed through short-channel narrow-channel and small-geometry effects that are investigated, in detail, in terms of the threshold voltage. The DIBL effect becomes significant for a short-channel device with a channel length of $<\;3({\mu}m)$. For narrow-channel devices the variation of the threshold voltage was sharp for $<4({\mu}m)$ due to the strong narrow-channel effect. In the case of small-geometry devices, the shift of the threshold voltage was less sensitive due to the combination of the DIBL and substrate bias effects, as compared with that observed from the short-channel and narrow-channel devices. The characterizing analysis of the narrow-channel and small-geometry devices, especially with channel width of $<\;4({\mu}m)$ and channel area of $<\;4{\times}4({\mu}m^2)$ respectively, can be accurately performed only from a 3-D numerical simulation due to their sharp variations in threshold voltages.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.203-206
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• 2008

There are lots of the narrow pass on alluvial channel of Korea. Most of research about this narrow pass of channel were focused on incremental effect of water level at backwater segment. In the meantime this research showed that it is important to valuate the river-bed variation at backward and forward around narrow pass. The sediment deposit at not only the backward of narrow pass but also the forward affected incremental effect of water level. The sediment deposit at the forward of narrow pass headed by sediment that passed through the narrow passed or scoured right around it.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.323-324
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• 2012

Flammability limits of opposed flow diffusion flame in a narrow channel was investigated experimentally and theoretically. There were three different extinction modes corresponding to high strain rate (HSR), low strain rate (LSR) and dilution ratio (DR) limits. To investigate these limits, a theoretical study was followed by focusing on flow and heat transfer characteristics. Consequently, a dead space concept that has been used for premixed flames was important to reveal the heat loss mechanism in a narrow channel especially for LSR conditions even in the case of diffusion flames.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.546-553
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• 2022

Narrow rectangular channels are employed in nuclear research reactors that use plate-type nuclear fuels, high heat-flux compact heat exchangers, and high-performance micro-electronics cooling systems. Two-phase flow in narrow rectangular channels is important, and it needs to be better understood because it is considerably different than that in round tubes. In this study, mechanistic models were developed for the flow regime transition criteria for various flow regimes in co-current air-water two-phase flow for vertical downward flow inside a narrow rectangular channel. The newly developed criteria were compared to a flow regime map of downward air-water two-phase flow inside a narrow rectangular channel with a 2.35-mm gap width under ambient temperature and pressure conditions. Overall, the proposed model showed good agreement with the experimental data.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.9-12
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• 2012

In this study, opposed flow combustion was re-visited in a narrow channel. Various flame behaviors were observed. Due to the confined structure of the combustor in this study, flame structures at very narrow strain rate could be stabilized and their characteristics were investigated. This study will be helpful to understand overall flame behavior of non-premixed flame in a narrow combustion space, and will also be useful to develop small combustors.

• Journal of the Korean Institute of Telematics and Electronics
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• v.22 no.6
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• pp.58-62
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• 1985

Analytical threshold voltage model of small size ion-implanted MOSFET's is proposed. Yau's model which is only applicable to MOSFET's with constant doping concentration was modified to handle the MOSFET's with nonuniform channel doping concentration and bird's beak, whereby the short and narrow-channel effect was quantitively described. Threshold voltage model for short-channel MOSFET's was derived by approximating the SUPREM result of channel impurity profile to a 2-step profile, and the narrow width be-haviour was successfully described using thr'weighting factor'to accommodate the doping profile in the bird's beak region.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.8
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• pp.981-987
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• 2019

In this paper, we propose a new SC-FDE (single carrier frequency domain equalization) structure to cope with narrow band interference signals or jammers and reduce pilot overhead. The conventional SC-FDE structure has a problem that the receiver performance degrades severely due to difficulty in time-domain channel estimation when narrow band jammers exist. In addition, the spectral efficiency is lowered by transmitting pilot at every SC-FDE block to estimate channel response. In order to overcome those problems, the proposed structure is devised to estimate frequency domain channel directly without time domain channel estimation. To reduce the pilot overhead, several data blocks are transmitted between two pilots. The channel estimate of each data block is found through linear interpolation of two channel estimates at two pilots. By performing frequency domain channel equalization using this channel estimate, the distortion by the channel is well compensated when narrow band jammers exist. The performance of the proposed structure is confirmed by computer simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.5
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• pp.787-793
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• 2018

In this paper, we propose a new single carrier - frequency domain equalization (SC-FDE) structure to cope with narrow band interference. In the conventional SC-FDE structure, when a high-power narrow band interference exists, channel estimation and data recovery is difficult. To relieve from this problem, this paper proposes a new SC-FDE frame structure to enable frequency-domain channel estimation in the environments that exist narrow band interference. Specifically, in the conventional method, the channel estimation is performed in time-domain first and from that, the frequency-domain channel is obtained by Fourier transform. In contrast, we proposed a new SC-FDE structure to enable frequency-domain channel estimation directly from received signals without time-domain channel estimation. The receiver performance improvement is verified through computer simulation. According to the results, the proposed technique can detect the signal with less than 2 dB loss compared with jammer-free environments, while the conventional method does not communicate with each other.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.1
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• pp.102-109
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• 2016

The hydrodynamic interaction between two large vessels can't be neglected when two large vessels are closed to each other in restricted waterways such as in a harbor or narrow channel. This paper is mainly concerned with the ship maneuvering motion based on the hydrodynamic interaction effects between two large vessels moving each other in curved narrow channel. In this research, the characteristic features of the hydrodynamic interaction forces between two large vessels are described and illustrated, and the effects of velocity ratio and the spacing between two vessels are summarized and discussed. Also, the Inchon outer harbor area through the PALMI island channel in Korea was selected, and the ship maneuvering simulation was carried out to propose an appropriate safe speed and distance between two ships, which is required to avoid sea accident in confined waters. From the inspection of this investigation, it indicates the following result. Under the condition of $SP_{12}{\leq}0:5L$, it may encounter a dangerous tendency of grounding or collision due to the combined effect of the interaction between ships and external forces. Also considering the interaction and wind effect as a parameter, an overtaken and overtaking vessel in narrow channel can navigate while keeping its own original course under the following conditions; the lateral separation between two ships is about kept at 0.6 times of ship length and 15 degrees of range in maximum rudder angle. On the other hand, two ships while overtaking in curved narrow channel such as Inchon outer harbor in Korea should be navigated under the following conditions; $SP_{12}$ is about kept at 1.0 times of ship length and the wind velocity should not be stronger than 10 m/s.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.66-72
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• 2004

The heat transfer and pressure drop characteristics of $CO_{2}$ are substantially different from those for CFC and HCFC refrigerants. In addition, geometric effects on two-phase flow patterns of $CO_{2}$ are also very significant in many respects. Therefore, two-phase flow patterns of $CO_{2}$ in a narrow rectangular channel or a small diameter tube whose gap size or hydraulic diameter is less than 2 mm are very important to understand heat transfer characteristics and to develop an appropriate heat transfer correlation. In the present study, the evaporation process of $CO_{2}$ in a narrow rectangular channel is visualized at various test conditions, and then the effects of operating conditions are analyzed.