• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.559-560
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• 2008

In this paper, I proposed 10bits 40MS/s Pipelined A/D converter. The op-amps for SHA and MDAC designed folded-cascode amplifier with gain-booster. And the MOS transistors with a low threshold voltage are employed to low on-resistor and parasitic capacitance. The power dissipation is 119㎽ at 1.2V and 40MS/s

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.313-318
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• 2003

The development of new materials with light weight and high strength has become vital to the machinery, aircraft and auto industries. However, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress(in this thesis). The compressive residual stress was imposed on the surface according to each shot velocity(57, 70, 83, 96 m/sec) based on Shot-peening, which is the method of improving fatigue lift: and strength. By using the methods mentioned above, I arrived at the following conclusions 1. The fatigue crack growth rate(da/dN) of the Shot-peened material was lower than that of the Un-peened material. And in stage I, ${\Delta}K_{th}$, the threshold stress intensity factor, of the shot-peen processed material is high in critical parts unlike the Un-peened material. Also m, fatigue crack growth exponent and number of cycle of the Shot-peened material was higher than that of the Un-peened material. That is concluded from effect of da/dN. 2. Fatigue life shows more improvement in the Shot-peened material than in the Un-peened material. And compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.171-172
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• 2007

We fabricated the metal-ferroelectric-insulator-semiconductor filed-effect transistors (MFIS-FETs) using the $(Bi,La)_4Ti_3O_{12}\;and\;LaZrO_x$ thin films. The $LaZrO_x$ thin film had a equivalent oxide thickness (EOT) value of 8.7 nm. From the capacitance-voltage (C-V) measurements for an Au/$(Bi,La)_4Ti_3O_{12}/LaZrO_x$/Si MFIS capacitor, a hysteric shift with a clockwise direction was observed and the memory window width was about 1.4 V for the bias voltage sweeping of ${\pm}9V$. From drain current-gate voltage $(I_D-V_G)$ characteristics of the fabricated Fe-FETs, the obtained threshold voltage shift (memory window) was about 1 V due to ferroelectric nature of BLT film. The drain current-drain voltage $(I_D-V_D)$ characteristics of the fabricated Fe-FETs showed typical n-channel FETs current-voltage characteristics.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.12
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• pp.2899-2904
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• 2015

This paper introduces about the effect on $I_{DS}-V_{GS}$ characteristic of transistor that interface trap charge is created by damage due to heat in a 3D sequential inverter. A interface trap charge distribution in oxide layer in a 3D sequential inverter is extracted using two-dimensional device simulator. The variation of threshold voltage of top transistor according to the gate voltage variation of bottom transistor is also described in terms of Inter Layer Dielectric (ILD) length of 3D sequential inverter, considering the extracted interface trap charge distribution. The extracted interface trap density distribution shows that the bottom $HfO_2$ layer and both the bottom and top $SiO_2$ layer were relatively more affected by heat than the top $HfO_2$ layer with latest process. The threshold voltage variations of the shorter length of ILD in 3D sequential inverter under 50nm is higher than those over 50nm. The $V_{th}$ variation considering the interface trap charge distribution changes less than that excluding it.

• Journal of Ocean Engineering and Technology
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• v.16 no.5
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• pp.73-79
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• 2002

In this paper, the effect of the compressive residual stresses was obtained at the test conditions of the higher temperature than the ambient temperature. The examination was performed with the CT specimen result of the material(JISG SUP9) which is being commonly used for the marine engine parts and the ocean structures. As a result, the test conditions at the higher temperature were acquired considering the peak values of the compressive residual stresses of the specimens and the effect on the fatigue crack propagation speed da／dN in stage II and the threshold stress intensity factor range Δth in stage I. Also the material constant C and the fatigue crack propagation index m in the formula of Paris Law da／dN＝C (ΔK)$^{m}$ were suggested to estimate the dependence on the test temperature.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.191-194
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• 1999

Switching behaviour of the ferroelectric thin film and device characteristics of the MFSFET (Metal-Ferroelectric-Semiconductor FET) are simulated with taking into account the accumulation of oxygen vacancies near interface between the ferroelectric thin film and the bottom electrode caused by the progress of fatigue. We show net switching current decreases due fatigue in the switching model. It indicates that oxygen vacancy strongly suppresses polarization reversal. The difference of saturation drain current of the device before fatigue is shown by the dual threshold voltages in I$_{D}$-V$_{D}$ curve as 6㎃/$\textrm{cm}^2$ and decreases as much as 50% after fatigue. Our simulation model is expected to play an important role in estimation of the behavior of MFSFET device with various ferroelectric thin films.lms.

• Journal of Veterinary Clinics
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• v.15 no.2
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• pp.410-416
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• 1998

These experiments were designed to evaluate the possibility of brain-stem auditory evoked responses(BAER) as a diagnostic tool for deafness in dogs. The BAER was recorded from three different groups of dogs; the normal dogs,'dog with otitis externa and dogs with unilateral destruction of cochlear. BAER of the normal dogs was consisted of distinct five peaks(I, II, III-IV, V). Furthermore, the clear shapes of waveform were observed at 85 dB. The latency of BAER was increased with reducing the intensity of sound-stimulus. The highest threshold of BAER was measured at 2 KHz with 10-30 dB. Dog with otitis externs demonstrated unclear shapes of BAER compared to the that of normal dogs. In the dogs with unilateral destruction of cochlear, the flat and indistinct waveform of BAER was recorded from the cochlear destroyed ear while that of BAER from normal side of ears did not show any differences from the normal BAER. These results indicate that the BAER can be clinically used in order to diagnose the deafness in dogs.

• Journal of the Semiconductor & Display Technology
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• v.9 no.4
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• pp.7-12
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• 2010

Field-emission characteristics of carbon nanotubes(CNTs), which were grown on conical-type tungsten micro-tips by using an electrophoretic deposition(EPD) method, were examined. The EPD method proved to be convenient to manipulate and arrange CNTs from well dispersed suspensions onto such tip-type substrates. The growth rate of CNTs was proportional to the applied d.c. bias voltage and the process time. It was observed from the Raman study that the EPDproduced CNTs showed better crystal qualities with the Raman intensity ratio( $I_D$/$I_G$) of 0.41-0.42 than the CVD-produced CNTs and their crystal qualities could be further improved by thermal annealing. The electron emitters based on the EPDCNTs showed excellent field emission properties, such as the threshold voltage for electron emission of about 620 V and the maximum emission current of about 345 ${\mu}A$. In addition, the EPD-CNTs exhibited the stable long-term(up to 40 h) emission capability and the emission stability was enhanced by thermal annealing.

• Korean Journal of Optics and Photonics
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• v.6 no.3
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• pp.228-232
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• 1995

We have made modulation doped SMQW-PBH-DFB-LD for high speed optical communications. The waveguide and barrier layers were doped by Zn with the concentration of $1.2 \times 10^{18}cm^{-1}$. Mean threshold current and slope efficiency were 24.88 mA (minimum 16 mA) and 0.197 mW/mA (maximum 0.275 mW/mA) respectively. Linewidth enhancement factor ($\alpha$) of MD-SMQW-PBH-DFB-LD was reduced than that of SMQW-PBH-DFB-LD. Linewidth enhancement factor of 1.8 owes to the large gain coefficient of modulation doped active layer. The resonance frequency was linearly increased with the square root of optical power. The resonance frequency in small signal modulation was measured as 8 GHz and -3 dB modulation bandwidth was 10 GHzat $46mA(I_{th}+30mA)$..

• Journal of the Korean Society of Safety
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• v.37 no.6
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• pp.148-157
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• 2022

Every year, particularly during the monsoon rainy season, landslides at the Chuncheon province of South Korea cause tremendous damage to lives, properties, and infrastructures. More so, the high rainfall intensity and long rainfall days that occurred in 2020 have increased the water content in the soil, thereby increasing the chances of landslide occurrences. Besides this, the rainfall thresholds and characteristics responsible for the initiation of landslides in this region have not been properly identified. Therefore, this paper addresses the rainfall thresholds responsible for the initiation of landslides at Chuncheon from a regional perspective. Using data obtained from rainfall measurements taken from 2002 to 2011, we identify a threshold relationship between rainfall intensity and rainfall duration for the initiation of landslides. In addition, we identify the relationship between the rainfall intensity using a 3-day, 7-day, and 10-day antecedent rainfall observation. Specifically, we estimate the rainfall data at 8 sites where debris flow occurred in 2011 by kriging. Following this, the estimated data are used to construct the relationship between the intensity (I), duration (D), and frequency (F) of rainfall. The results of the intensity-duration-frequency (IDF) analysis show that landslides will occur under a rainfall frequency below a 2-year return period at two areas in Chuncheon. These results will be effectively used to design structures that can prevent the occurrence of landslides in the future.