• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.12
• /
• pp.1017-1021
• /
• 2007

To implement tera bit level non-volatile memories of low power and fast operation, proving statistical reproductivity and satisfying reliabilities at the nano-scale are a key challenge. We fabricate the charge trapping nano scaled SONOS unit memories and 64 bit flash arrays and evaluate reliability and performance of them. In case of the dielectric stack thickness of 4.5 /9.3 /6.5 nm with the channel width and length of 34 nm and 31nm respectively, the device has about 3.5 V threshold voltage shift with write voltage of $10\;{\mu}s$, 15 V and erase voltage of 10 ms, -15 V. And retention and endurance characteristics are above 10 years and $10^5$ cycle, respectively. The device with LDD(Lightly Doped Drain) process shows reduction of short channel effect and GIDL(Gate Induced Drain Leakage) current. Moreover we investigate three different types of flash memory arrays.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.2
• /
• pp.887-890
• /
• 2005

The double gate(DG) MOSFET is a promising candidate to further extend the CMOS scaling and provide better control of short channel effect(SCE). DGMOSFETs, having ultra thin updoped Si channel for SCEs control, are being validated for sub-20nm scaling, A channel effects such as the subthreshold swing(SS), and the threshold voltage roll-off(${\Delta}V_{th}$). The propsed model includes the effects of thermionic emission and quantum tunneling of carriers through the source-drain barrier. The proposed model is used to design contours for gate length, channel thickness, and gate oxide thickness.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2004.05b
• /
• pp.658-660
• /
• 2004

In this paper, we have investigated electrical characteristics about doble gate MOSFET with changed oxide layer thickness of nam Sate and side gate, main gate and Si-substrate. We have known that optimum thickness of nam gate and side gate at 4nm, gate and Si-substrate at 3nm. We have applied for side gate voltage 3V, and drain voltage 1.5V. finally, we have known that importance of oxide layer thickness between main gate and Si-substrate better than main gate and side Sate.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.7
• /
• pp.1668-1672
• /
• 2009

In this study, the method by Robertson which has been most commonly used for classifying soils, using piezocone test results, was compared with that by Schneider which was most recently proposed. Both methods were applied to the soils in Gyeonggi province and the classifying results were investigated. It has been found that the difference between the results according to the methods was not so large and Schneider's method showed slightly better results for clay region and vice versa. Such factors as large field database, normalized tip resistance, pore water pressure, and drain condition were found to need further research for more reliable soil classification.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.2
• /
• pp.104-109
• /
• 2019

An analytical threshold voltage model is proposed to analyze the threshold voltage roll-off and drain-induced barrier lowering (DIBL) for a junction-based double-gate (JBDG) MOSFET and a junction-less double-gate (JLDG) MOSFET. We used the series-type potential distribution function derived from the Poisson equation, and observed that it is sufficient to use n=1 due to the drastic decrease in eigenvalues when increasing the n of the series-type potential function. The threshold voltage derived from this threshold voltage model was in good agreement with the result of TCAD simulation. The threshold voltage roll-off of the JBDG MOSFET was about 57% better than that of the JLDG MOSFET for a channel length of 25 nm, channel thickness of 10 nm, and oxide thickness of 2 nm. The DIBL of the JBDG MOSFET was about 12% better than that of the JLDG MOSFET, at a gate metal work-function of 5 eV. It was also found that decreasing the work-function of the gate metal significantly reduces the DIBL.

• Korean Journal of Agricultural Science
• /
• v.25 no.2
• /
• pp.225-234
• /
• 1998

This study was compared the degree of consolidation by Hyperbolic, Curve fitting, Asaoka's, Monden's methods using measured value with theoretical curve in consideration of smear effect and well resistance. The results of the study were summarized as follows ; 1. The degree of consolidation by Hyperbolic method was underestimated than the degree of consolidation by Curve fitting, Asaoka's, and Monden's methods. 2. Typical range of horizontal coefficient of consolidation was $C_h=(2{\sim}3)C_v$ in the case considering smear effect and well resistance, and $C_h=(0.5{\sim}2.5)C_v$ in the case disregarding smear effect and well resistance. 3. The degree of consolidation obtained by ground settlement monitoring was nearly same value when the coefficient of permeability of smear zone by back analysis was shown the half that of in-situ and the diameter of smear zone was shown double that of mendrel. 4. Increasing of diameter reduction ratio of drain, the time of consoildation was delayed. The affection of well resistance the case of small coefficient of permeability was much more than that in the case of large coefficient of permeability. It was recommended that design of diameter reduction of drain consider smear effect and well resistance.

• Journal of the Korean Geosynthetics Society
• /
• v.15 no.1
• /
• pp.47-57
• /
• 2016

Many researchers reported that artesian pressure exists in thick soft ground of Busan Nakdong river estuary. Artesian pressure in soft ground could affect rate of consolidation, settlement and drainage capasity of prefabricated vertical drain(PVD). This paper investigated consolidation behaviors of soft ground with partially penetrated PVD subjected to artesian pressure. Laboratory tests with 1-dimensional large column equipment and their numerical analyses were carried out. Test results showed that the consolidation settlement of clay ground with artesian pressure was higher than that without artesian pressure. Due to artesian pressure, the dissipation rate of excess pore water pressure was reduced in soft ground with artesian pressure, especially at bottom part of clay ground. Numerical results were in good agreement with experimental test results.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.39 no.4
• /
• pp.25-35
• /
• 2002

This work describes an 8b 200MHz time-interleaved subranging analog-to-digital converter (ADC) based on a single-poly digital CMOS process. Two fine ADCs for lower digital bits of the proposed ADC employ a time-sharing double-channel architecture to increase system speed and a new reference voltage switching scheme to reduce settling time of the reference voltages and chip area. The proposed intermeshed resistor string, which generates reference voltages for fine ADCs, improves linearity and settling time of the reference voltages simultaneously. The proposed sample- and-hold amplifier(SHA) is based on a highly linear common-drain amplifier and passive differential circuits to minimize power consumption and chip area with 8b accuracy and employs input dynamic common mode feedback circuits for high dynamic performance at a 200MHz sampling rate. A new encoding circuit in a coarse ADC simplifies the signal processing between the coarse ADC and two successive fine ADCs.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.64 no.2
• /
• pp.27-35
• /
• 2022

Based on the current status of groundwater usage in the dry season through field surveys, this study tried to suggest countermeasures to reduce groundwater usage and to improve the water quality of baseflow from agricultural fields. For this purposes, basins with water curtain cultivation preceded were targeted where decreases of groundwater due to continuous use of groundwater in spring and winter annually observed. From monitoring groudwater usage of the study watershed, 130,058, 130,105 m³/day of water was pumped in during the water curtain cultivation period (October-February) in the Shindun, Seokwon watershed respectively. And the pilot application of the smart automated sensor-based water curtain cultivation system (smart WC system) developed in this study to reduce groundwater consumption has been conducted. As a result, the efficiency of the smart WC system when threshold temperature is set as 6.3 ℃ was 21.1% compared to conventional cultivation and efficiency increased as threshold temperature gets lower. Lastly, in this study, culvert drainage and Bio-filters were installed and rainfall monitoring was performed 15 times in order to analyze the baseflow securement and pollutant loads behavior. As a result, the test-bed with culvert drainage and Bio-filter installed together generated 61.4% more baseflow (4.974 m³) than the test-bed with only culvert drainage was installed (3.056 m³). However, the total pollutant load of all water quality contents (BOD, COD, T-N, TOC) except for the SS and T-P was found to be greater in the culvert drain and Bio-filter installed than in the culvert drain test-bed.

• Journal of the Korean GEO-environmental Society
• /
• v.24 no.1
• /
• pp.45-50
• /
• 2023

In order to prevent slope disasters caused by rainfall, it is very important to quickly exclude rainfall. In Korea, horizontal drainage holes with excellent economic feasibility and construction performance are generally applied as a method to lower the underground water level. However, horizontal drainage holes constructed on the site are often uniformly constructed regardless of the presence or absence of other water or ground conditions, and it is often difficult to expect drainage performance of horizontal drainage holes due to poor maintenance. In this study, an artificial ground was created using model construction and horizontal drainage experiments were conducted to measure the amount of horizontal drainage drain in a certain amount of control area 0%, 25%, 50%, 75%, and an evaluation table (draft) that can quantitatively evaluate horizontal drainage based on measurements and design documents is proposed as basic data.