• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.201-202
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• 2005

The electrical characteristics of high-voltage LDMOSFET (Lateral Double-diffused MOSFET) fabricated by a CMOS technology were investigated depending on the process and design parameters. The off-state breakdown voltages of n-channel LDMOSFETs were linearly increased with increasing to the drift region length. For the case of decreasing n-well ion implant doses from $1.0\times10^{13}/cm^2$ to $1.0\times10^{12}/cm^2$, the off-state breakdown voltage was increased approximately two times, however, the on-resistance was also increased about 76%. Moreover, the on- and off-state breakdown voltages were also linearly increased with increasing the channel to n-tub spacing due to the reduction of impact ionization at the drift region.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.5
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• pp.518-522
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• 2009

The mesh selectivity of drift gill net for yellow croaker (Larimichthys polyactis) was examined in field experiments with six different net mesh size (40, 45, 50, 55, 60 and 65 mm) from April to December, 2008 in the northwestern coastal waters of Gageo-do, Korea. The total catch of 8,091 consisted of yellow croaker (n=7,574; 89.5% of total catch), common mackerel (n=162; 4.8%) and other species (n=355; 5.8%). The selectivity curve for the small size yellow croaker was fit by Kitahara's method to the polynomial equation S(R)=exp{($-0.552R^3$+$4.927R^2$-11.591R+9.320)-6.717}. The optimal mesh size for 50% retention for minimum landing size(191mm) of yellow croaker was estimated as 51.1 mm. This is very similar to the current drift net mesh size used in Gageo-do.

• Nonlinear Functional Analysis and Applications
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• v.27 no.4
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• pp.813-837
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• 2022

In this paper we consider inverse problem for a general class of nonlinear stochastic differential equations on Hilbert spaces whose generating operators (drift, diffusion and jump kernels) are unknown. We introduce a class of function spaces and put a suitable topology on such spaces and prove existence of optimal generating operators from these spaces. We present also necessary conditions of optimality including an algorithm and its convergence whereby one can construct the optimal generators (drift, diffusion and jump kernel).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.292-295
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• 2002

In this work, transient characteristics of NPT(Non Punch Through)-IGBT(Insulated Gate Bipolar Transistor) have been studied with different temperatures analytically. Power losses are caused by heat generated in MIT-IGBT for steady state and transient state conditions. We therefore have focused on the analysis of excess carrier concentration and excess charge injected into N-drift layer with different temperatures and have obtained anode voltage drop during turn-off with lifetime of 2.4[${\mu}$s].

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.911-915
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• 2004

In this study, the electrical characteristics of high-voltage LDMOSFET fabricated by the existing CMOS technology were investigated depending on its process and design parameter. In order to verify the experimental data, two-dimensional device simulation was carried out simultaneously. The off- state breakdown voltages of n-channel LDMOSFETs were increased nearly in proportional to the drift region length. For the case of decreasing n-well ion implant doses from $1.0\times{10}^{13}/cm^2$ to $1.0\times{10}^{12}/cm^2$, the off-state breakdown voltage was increased approximately two times. The on-resistance was also increased about 76 %. From 2-D simulation, the increase in the breakdown voltage was attributed to a reduction in the maximum electric field of LDMOS imolanted with low dose as well as to a shift toward n+ drain region. Moreover, the on- and off-state breakdown voltages were also linearly increased with increasing the channel to n-tub spacing due to the reduction of impact ionization at the drift region. The experimental and design data of these high-voltage LDMOS devices can widely applied to design smart power ICs with low-voltage CMOS control and high-voltage driving circuits on the same chip.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.29-32
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• 2001

We measured the electron transport coefficients(the electron drift velocity, W, and the longitudinal diffusion coefficient, $D_L$) in pure $CF_4$ over the E/N range from 0.04 Td to 250 Td by the double shutter drift tube. And these electron transport coefficients in pure $CF_4$ were calculated over the E/N range from 0.01 to 250 Td at 1 Torr by using the two-term approximation of the Boltzmann equation.

• Proceedings of the KIEE Conference
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• 2008.11b
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• pp.85-88
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• 2008

Drift velocities and Distribution Function for electrons in $SF_6$-Ar mixtures gas used by MCS-BEq algorithm has been analysed over the E/N range $30{\sim}300[Td]$ by a two term Boltzmann equation and by a Monte Carlo simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2[%] and 0.5[%] $SF_6$-Ar mixtures were measured by time-of-flight method, The results show that the deduced electron drift velocities agree reasonably well with theoretical for a rang of E/N values The results simulation have been compared with present and previously obtained data and respective set of electron collision cross sections of the molecules.

• Nuclear Engineering and Technology
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• v.8 no.1
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• pp.29-40
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• 1976

An investigation on the effect of electrostatic drift field which can bring an additional aid to the photogenerated carrier collection in one side of the silicon solar cell has been carried out. The drift field was produced by the gradient of boron concentration in the p-type side in virtue of the strain compensation due to the tin dopant. A new method of ion implantation which is based on the principle of chiefly radiation-enhanced diffusion is adopted for forming the p-n junction in the solar cell. The open circuit voltage and the conversion efficiency of the ion-implanted silicon solar cell sample can be figured out to be 0.44 V and 5%, respectively.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.176-184
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• 1996

To overcome the drawbacks of conventional LDMOSFETs, we propose RESURF EDMOSFETs which can be adapted in varous circuit applications, be driven without charge pumping circuity and thowe threshold voltage can be adjusted. The devices have the diffused drift region formed by a high tmperature process before the gate oxidaton. After the polysilicon gate electrode formation, a fraction of the drift region around the gate edge is opened for supplemental self-aligned ion implantation to obtain self-aligned drift region. This leads to a shorter gate length and desirable drift region junction contour under the gate edge for minimum specific-on-resistance. In additon, a and maximize the breakdown voltage. Also, by biasing the metal field plate, we can reduce the specific-on-resistance further. The devices are optimized by using the TSUPREM-4 process simulator and the MEDICI device simulator. The optimized devices have the breakdwon voltage and the specific-on-resistance of 101.5V and 1.14m${\Omega}{\cdot}cm^{2}$, respectively for n-channel RESURF EDMOSFET, and 98V and 2.75m.ohm..cm$^{2}$ respectively for p-channel RESURF EDMOSFET. To check the validity of the simulations, we fabricated n-channel EDMOSFETs and confirmed the measured breakdown voltage of 97V and the specific-on-resistance of 1.28m${\Omega}{\cdot}cm^{2}$. These results are superior to those of any other reported power devices for smart power IC applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.201-203
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• 2001

This paper describes the information for quantitative simulation of weakly ionized plasma. We must grasp the meaning of the plasma state condition to utilize engineering application and to understand materials of plasma state. In this paper, the drift velocity of electron in Xenon gas calculated for range of E/N values from 0.01~500[Td] at the temperature is $300[^{\circ}K]$ and pressure is 1[Torr], using a set of electron collision cross sections determined by the authors and the values of drift velocity of electrons are obtained for TOF, PT, SST sampling method of Backward Prolongation by two term approximation Boltzmann equation method. it has also been used to predict swarm parameter using the values of cross section as input. The result of Boltzmann equation, the drift velocity of electrons, has been compared with experimental data by L. S. Frost and A. V. Phelps for a range of E/N. The swarm parameter from the study are expected to server as a critical test of current theories of low energy scattering by atoms and molecules.