• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.518-519
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• 2005

We have studied the transmittance of fringe-filed switching(FFS) using a liquid crystal with positive dielectric anisotropy. Generally, FFS having positive dielectric anisotropy has less transmittance than FFS using negative dielectric anisotropy. FFS mode transmittance depends on horizontal director deformation, however fringe filed is composed of vertical and horizontal field. Vertical field in the middle of electrode suppresses the transmittance of FFS mode, especially when we use positive one. So, it is important to prevent the LC director from the effect of vertical field. We changed the splay elastic constant and checked the transmittance. The transmittance of FFS having positive dielectric anisotropy was improved. Less tilted LC directors improve the transmittance of FFS using positive dielectric anisotropy. We can improve the transmittance by using LC which have high splay elastic constant when another LC properties are equal.

• 한국실내디자인학회논문집
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• 제22권3호
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• pp.33-42
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• 2013

The purpose of this study was to analyze the design trend of the vertical garden design in the indoor space through the examples of green wall in the lobby space. For the analysis, this study looks into the 'Guide for the Building Greening System' to understand the technical consideration for the green wall. After that, the key design elements was drawn from existing green walls through the literature review and field survey and field-survey. The study picked six green walls which was completed after 2000 in the lobby space in Seoul. The major findings of this study were as follows: First, the design factors mainly depend on the plant selection, which leads to the outlook and texture of the vertical walls. The texture is expressed by the two-dimensional or three-dimensional planting methods which is related to the selection of plant species. Second, the vertical walls in the lobby area should be planned for the function of space which could be transition, human traffic, mood and attraction. Third, the vertical wall should be integrated with the surroundings in order to reinforces the dynamic or static space experience.

• 센서학회지
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• 제27권5호
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• pp.275-279
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• 2018

In this study, we introduce a sensing platform based on a plasmonic metasurface absorber (MA) with a vertical nanogap for the ultrasensitive detection of monolayer molecules. The vertical nanogap of the MA, where the extremely high near-field is uniformly distributed and exposed to the external environment, is formed by an under-cut structure between a metallic cross nanoantenna and the mirror layer. The accessible sensing area and the enhanced near-field of the MA further enhance the sensitivity of surface-enhanced infrared absorption for the target molecule of 1-octadecanethiol. To provide strong coupling between the molecular vibrations and plasmonic resonance, the design parameters of the MA with a vertical nanogap are numerically designed.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.65-68
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• 2003

A quantitative study of the amount of air transported between the boundary layer and the free atmosphere is important for understanding air quality and upper tropospheric ozone, which is a greenhouse gas. Frontal systems are known to be an effective mechanism for the vertical transport of pollutants. Numerical experiments have been performed with a simple two-dimensional front model to simulate vertical transport of trace gases within developing cold fronts. Three different trace gases experiments have been done numerically according to the different initial fields of trace gases such as aerosol, ozone and $H_2O_2$. Trace gas field tilts to the east while the front tilts to the west. Aerosol simulation shows that pollutants can be transported out of the boundary to altitudes of about 10 km. The stratospheric ozone is brought downwards in a tropopause fold behind of the frontal surface. The meridional gradient in trace gas ($H_2O_2$) can cause a complicate structure in the trace field by the meridional advection.

• 한국지반공학회논문집
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• 제16권2호
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• pp.71-77
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• 2000

In this paper, consolidation settlements with time at vertical drain sites were predicted by artificial neural networks. Laboratory test results and field measurements of two vertical drain sites were used for training and testing neural networks. Predicted consolidation settlements by trained artificial neural networks were compared with measured settlements by field instrumentation. To improve the prediction accuracy, modular artificial neural networks were studied. From the results of applying artificial neural networks to the same situation, it was shown that modular artificial neural network model was more accurate for the prediction of the consolidation settlements than the general model.

• 전기의세계
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• 제30권10호
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• pp.645-654
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• 1981

A technique has been proposed for fabricating a submicron channel vertical V-groove JFET using standard photolithography. A finite element numerical simulation of the V-groove JFET operation was performed using a FORTRAN progrma run on a Cyber-174 computer. The numerical simulation predicts pentode like common source output characteristics for the p$^{+}$n Vertical V-groove JFET with maximum transconductance representing approximately 6 precent of the zero bias drain conductance value and markedly high drain conductance at large drain voltages. An increase in the acceptor concentration of the V-groove JFET gate was observed to cause a significant increase in the transconductance of the device. Therefore, as above mentioned, this paper is study on the analysis of a Vertical V-groove Junction Field Effect Transistor with Finite Element Method.d.

• Journal of the Optical Society of Korea
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• 제20권5호
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• pp.628-632
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• 2016

We studied experimentally and theoretically the vertical range of the confined electric field in the gap area of metamaterials, which was analyzed for various gap widths using terahertz time-domain spectroscopy. We measured the resonant frequency as a function of the thickness of poly(methyl methacrylate) in the range 0 to 3.2 μm to quantify the effective detection volumes. We found that the effective vertical range of the metamaterial is determined by the size of the gap width. The vertical range was found to decrease as the gap width of the metamaterial decreases, whereas the sensitivity is enhanced as the gap width decreases due to the highly concentrated electric field. Our experimental findings are in good agreement with the finite-difference time-domain simulation results. Finally, a numerical expression was obtained for the vertical range as a function of the gap width. This expression is expected to be very useful for optimizing the sensing efficiency.

• Geomechanics and Engineering
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• 제13권6호
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• pp.963-975
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• 2017

Improvement of soft clay deposit by preloading with vertical drains is one of the most popular techniques followed worldwide. These drains accelerate the rate of consolidation by shortening the drainage path. Although the analytical and numerical solutions available are mostly based on equal strain hypothesis, the adoption of free strain analysis is more realistic because of the flexible nature of the imposed surcharge loading, especially for the embankment loading used for transport infrastructure. In this paper, a numerical model has been developed based on free strain hypothesis for understanding the behaviour of soft ground improvement by vertical drain with preloading. The unit cell analogy is used and the effect of smear has been incorporated. The model has been validated by comparing with available field test results and thereafter, a hypothetical case study is done using the available field data for soft clay deposit existing in the eastern part of Australia and important conclusions are drawn therefrom.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.281-281
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• 2014

The field emission properties of GaN are reported in the present study. To be a good field emitter, it requires a low work function, high aspect ratio, and strong mechanical stability. In the case of GaN, it has a quite low work function (4.1eV) and strong chemical/mechanical/thermal stabilities. However, so far, it was difficult to fabricate vertical GaN nanostructures with a high aspect ratio. In this study, we successfully achieved vertically well aligned GaN nanostructures with chemical vapor-phase etching methods [1] (Fig. 1). In this method, we chemically etched the GaN film using hydrogen chloride and ammonia gases at high temperature around $900^{\circ}C$. This process effectively forms vertical nanostructures without patterning procedure. This favorable shape of GaN nanostructures for electron emitting results in excellent field emission properties such as a low turn-on field and long term stability. In addition, we observed a uniform fluorescence image from a phosphor film attached at the anode part. The turn-on field for the GaN nanostructures is found to be about $0.8V/{\mu}m$ at current density of $20{\mu}A$/cm^2. This value is even lower than that of typical carbon nanotubes ($1V/{\mu}m$). Moreover, threshold field is $1.8V/{\mu}m$ at current density of $1mA$/cm^2. The GaN nanostructures achieved a high current density within a small applied field range. We believe that our chemically etched vertical nanostructures are the promising structures for various field emitting devices.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권2호
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• pp.172-178
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• 2016

In this paper, we propose a sub-10 nm Ge/GaAs heterojunction-based tunneling field-effect transistor (TFET) with vertical band-to-band tunneling (BBT) operation for ultra-low-power (LP) applications. We design a stack structure that is based on the Ge/GaAs heterojunction to realize the vertical BBT operation. The use of vertical BBT operations in devices results in excellent subthreshold characteristics with a reduction in the drain-induced barrier thinning (DIBT) phenomenon. The proposed device with a channel length ($L_{ch}$) of 5 nm exhibits outstanding LP performance with a subthreshold swing (S) of 29.1 mV/dec and an off-state current ($I_{off}$) of $1.12{\times}10^{-11}A/{\mu}m$. In addition, the use of the highk spacer dielectric $HfO_2$ improves the on-state current ($I_{on}$) with an intrinsic delay time (${\tau}$) because of a higher fringing field. We demonstrate a sub-10 nm LP switching device that realizes a good S and lower $I_{off}$ at a lower supply voltage ($V_{DD}$) of 0.2 V.