• 한국해양학회지
• /
• v.17 no.2
• /
• pp.51-58
• /
• 1982

Density inversions are investigated by using the oceanographic data of temperature and salinity obtained in the Japan Sea Srom 1965 To 1979. The density inversions are found more frequently in winter than summer. About one half of the Japan Sea has the density inversions in winter, while in summer, they appear only in the small part os the Korean Strait. The inversions are usually sormed surface layers of a few tens of meters. Such phenomena can be explained by the advection of cold water in the suface layer by Ekman drift: In winter, the southward flow of surface cold water due to northwesterly monsoon causes the density inversions, and in summer, surface layer on the Korean strit unstable.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2013.05a
• /
• pp.97-97
• /
• 2013

We present a comprehensive study on the integration of h-BN with silicon MOSFET. Temperature dependent mobility modeling is used to discern the effects of top-gate dielectric on carrier transport and identify limiting factors of the system. The result indicates that coulomb scattering and surface roughness scattering are the dominant scattering mechanisms for silicon MOSFETs at relatively low temperature. Interposing a layer of h-BN between $SiO_2$ and Si effectively weakens coulomb scattering by separating carriers in the silicon inversion layer from the charged centers as 2-dimensional h-BN is relatively inert and is expected to be free of dangling bonds or surface charge traps owing to the strong, in-plane, ionic bonding of the planar hexagonal lattice structure, thus leading to a significant improvement in mobility relative to undecorated system. Furthermore, the atomically planar surface of h-BN also suppresses surface roughness scattering in this Si MOSFET system, resulting in a monotonously increasing mobility curve along with gate voltage, which is different from the traditional one with a extremum in a certain voltage. Alternatively, high-k dielectrics can lead to enhanced transport properties through dielectric screening. Modeling indicates that we can achieve even higher mobility by using h-BN decorated $HfO_2$ as gate dielectric in silicon MOSFETs instead of h-BN decorated $SiO_2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.2
• /
• pp.201-206
• /
• 2004

We have performed computer simulation and experiment to obtain electro-optic characteristics of reflective hybrid aligned nematic (R-HAN) cell driven by fringe field, in which the cell consists of polarizer, optical compensation film, LC layer and reflector. Conventional R-HAN cell driven by fringe field using only the LC layer shows high wavelength dispersion at dark-state and thus viewing angle characteristic is strongly wavelength-dependent. In order to improve this demerit, we added one optical compensation film to conventional R-HAN cell. The display with optimized cell parameters shows low wavelength dispersion at dark-state and exhibits a wide viewing angle without the occurrence of grey scale inversion over a wide range of viewing angles and the contrast ratio greater than 5 over exists about 120$^{\circ}$ in vortical direction and 160$^{\circ}$in horizontal direction. Experimental results show good agreements with theoretical results and fast response time.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.27 no.11
• /
• pp.49-54
• /
• 1990

In this paper, a simple model is presented for the gate-voltage dependence of the parasitic resistance in MOSFETs with the lightly-doped drain (LDD) structure. At the LDD region located under the gate electrode, an accumulation layer is formed due to the gate voltage. The parasitic resistance of the source side LDD in the channel is treated as a parallel combination of the resistance of the accumulation layer and that of the bulk LDD, which is approximated as a spreading resistance from the end of the channel inversion layer to the ${n^+}$/LDD junction boundary. Also the effects of doping gradients at the junction are discussed. As result of the model, the LDD resistance decreases with increasing the gate voltage at the linear regime, and increase quasi-linearly with the gate voltage at the saturation regime, considering th velocity saturation both in the channel and in the LDD region. The results are in good agreement with experimental data reported by others.

• Economic and Environmental Geology
• /
• v.18 no.2
• /
• pp.151-157
• /
• 1985

Events detected by the KIER microearthquake network operated in the Southern Part of Korea for 265 days in 1982~1984 were reviewed, and some of them were identified to be a dynamite explosion from several construction sites. The purpose of the present work is to determine the crustal structure of the Southern Korea using the time-destance data obtained from such explosion seismic records. The time·distance data can be well explained by a crustal model composed of four horizontal layers of which thickness, p and s-wave velocity ($V_p$ and $V_s$) are characterized as follows. 1st layer (surface) ; 0~2km, $V_p=5.5km/sec$, $V_s=3.3km/sec$ 2nd layer (upper crust) ; 2~15km, $V_p=6.0km/sec$, $V_s=3.5km/sec$ 3rd layer (lower crust) ; 15~29km, $V_p=6.6km/sec$, $V_s=3.7km/sec$ 4th layer (upper mantle) ; 29km~ , $V_p=7.7km/sec$, $V_s=4.3km/sec$ The relatively shallow crust·mantle boundary and low $P_n$ velocity compared with the mean values for stable intraplate region are noteworthy. Supposedely, it is responsible for the high heat flow in the South-eastern Korea or an anomalous subterranean mantle. The mean $V_p/V_s$ ratio calculated from the relation between p-wave arrival and s-p arrival times appears to be 1.735 which is nearly equivalent to the elastic medium of ${\lambda}={\mu}$. However, the ratio tends to be slightly larger with the depth. The ratio is rather high compared with that of the adjacent Japanese Island, and the fact suggests that the underlying crust and upper mantle in this region are more ductile and hence the earthquake occurrences are apt to be interrupted. As an alternative curstal model, a seismic velocity structure in which velocities are successively increased with the depth is also proposed by the inversion of the time·distance data. With the velocity profile, it is possible to calculate a travel time table which is appropriate to determine the earthquake parameters for the local events.

• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1925-1927
• /
• 1999

At the study, it has fabricated Al/AlN/GaAs MIS capacitor using DC reactive sputtering method. To applicate GaAs semiconductor in a MIS devices, investigated capability of AIN thin film by the insulator layer. Also it has investigated inversion of C-V characteristics by addition of the hydrogen(hydrogen concentration: 5%) and it has investigated that leakage current has $10^{-8}A/cm^2$ for 1 MV/cm breakdown electric field of I-V characteristics.

• Journal of Korea Society of Industrial Information Systems
• /
• v.6 no.3
• /
• pp.123-127
• /
• 2001

The prediction method of the parameter C/sub gs/ of CMOS transistor is proposed by calculating the mobil charge in inversion layer of COMS transistor. This parameter C/sub gs/ decided on the cutoff frequency in MOS transistor in RF range and coupled input and output. This parameter C/sub gs/ in RF range is very important parameter in small signal circuit model. This proposed method is contributed to developing software of extracting parameter value in equivalent circuit model. The method provide the important information to construct a RF nonlinear model for multifinger gate MOSFET. This method will be very valuable to develop a large signal MOSFET model for nonlinear RF IC design.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.36 no.6
• /
• pp.424-429
• /
• 1987

It has been observed that the reduction rate of the inversion layer carrier mobility due to the increase of the longitudinal electric field(drain to source direction) decreases as the transverse electric field increases. The effects of this physicar phenomenon to the I-V characteristics of the short channel NMOSFET are studied. It is shown that these effects increase the drain Current in the saturatio region, which agrees with the genarally observed decrepancy between the experimental I-V charateristics and the I-V modeling which dose not include this physical phenomenon. Also it is shown that this effect becomes more important when the device channel length decreases and the device operates in the high electric field range.

• Korean Journal of Materials Research
• /
• v.26 no.10
• /
• pp.556-560
• /
• 2016

Using current-voltage (I-V) and capacitance-voltage (C-V) measurements, the electrical properties of Au and Cu Schottky contacts to n-Ge were comparatively investigated. Lower values of barrier height, ideality factor and series resistance were obtained for the Au contact as compared to the Cu contact. The values of capacitance showed strong dependence on the bias voltage and the frequency. The presence of an inversion layer at the interface might reduce the intercept voltage at the voltage axis, lowering the barrier height for C-V measurements, especially at lower frequencies. In addition, a higher interface state density was observed for the Au contact. The generation of sputter deposition-induced defects might occur more severely for the Au contact; these defects affected both the I-V and C-V characteristics.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.188-188
• /
• 2006

We demonstrate two very simple and fast routes to fabricating ordered micro/nanopatterns of polymers over large areas on various substrates using controlled dewetting. The first method is based on utilizing microimprinting to induce the local thickness variation of an initially inverted bilayer which allows the controlled dewetting and partial layer inversion upon subsequent thermal annealing. In the second method, the self assembly of block copolymer was controlled on a chemically micropatterned surface produced by microcontact printing, being combined with its solvent vapor treatment. The kinetically driven, non-lithographical nanopattern structures were easily fabricated over large area by these approaches.