• JSTS:Journal of Semiconductor Technology and Science
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• 제12권2호
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• pp.186-192
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• 2012

Half-rail stacked drivers are used to reduce power consumption of the drivers for synchronous buck converters. In this paper, the stacked driver is optimized by matching the average charging and discharging currents used by high-side and low-side drivers. By matching the two currents, the average intermediate bias voltage can remain constant without the aid of the voltage regulator as long as the voltage ripple stays within the window defined by the hysteresis of the regulator. Thus the optimized driver in this paper can minimize the power consumption in the regulator. The current matching requirement yields the value for the intermediate bias voltage, which deviates from the half-rail voltage. Furthermore the required capacitance is also reduced in this design due to decreased charging current, which results in significantly reduced die area. The detailed analysis and design of the stacked driver is verified through simulations done using 5V MOSFET parameters of a typical 0.35-${\mu}m$ CMOS process. The difference in power loss between the conventional half-rail driver and the proposed driver is less than 1%. But the conventional half-rail driver has excess charge stored in the capacitor, which will be dissipated in the regulator unless reused by an external circuit. Due to the reduction in the required capacitance, the estimated saving in chip area is approximately 18.5% compared to the half-rail driver.

• 연구논문집
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• 통권28호
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• pp.219-227
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• 1998

In order to investigate the interfacial structure between TiN and iron nitride, an AISI 4140 steel was nitrided to form a layer of thickness 15$\mum$ by DC ion nitriding, then the surface was bombarded with Ti ions and subsequently coated a TiN film of 5$\mum$ by arc ion plating method. The interfacial microstructure between TiN and iron nitride was characterized by optical microscope, SEM and XRD. So called black layer was observed in the duplex treatment. It was resulted from the decomposition of iron nitride during the bombardment. Its thickness was increased with increasing bombardment time at high bias voltage. But the thickness was greatly decreased when the iron nitride was bombarded with a nitrogen gas or at a reduced bias voltage. The adhesion strength of the top TiN coating was decreased with increasing thickness of the black layer. Furthermore, the reduced adhesion strength in this system was discussed in view of the interfacial structural relationship between TiN and iron nitride.

• Korean Chemical Engineering Research
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• 제47권1호
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• pp.79-83
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• 2009

본 연구에서 고밀도 플라즈마 식각 장치를 사용한 비정질 실리콘 막의 게이트 전극선 형성공정에서 여러 가지 식각 변수가 치수 제어와 식각 속도 및 식각 선택비 등 식각 특성에 미치는 영향을 분석하였다. $Cl_2/HBr/O_2$로 구성된 식각 기체의 전체 유량을 증가시키면 비정질 실리콘의 식각 속도가 증가하나 식각 전후의 형상치수는 변화없이 거의 일정하였다. 전체 유량을 고정시키고 $Cl_2$와 HBr 간의 유량비를 변화시키면 HBr의 유량이 커질수록 비정질 실리콘의 식각 속도가 감소하였다. $O_2$의 유량을 증가시키면 산화막의 식각 속도가 상대적으로 낮아져 식각 선택비를 증가시켜 식각 공정의 안정성을 높이나 게이트 전극선을 경사지게 하는 특성을 보인다. Source power의 증가는 비정질 실리콘 식각 속도의 증가와 더불어 형상치수의 증가를 가져오며, bias power의 증가는 비정질 실리콘과 산화막의 식각 속도를 증가시키나 식각 선택비를 크게 감소시키는 경향을 보였다.

• 대기
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• 제32권4호
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• pp.277-295
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• 2022

The global weather prediction model, Korean Integrated Model (KIM), has been in operation since April 2020 by the Korea Meteorological Administration. This study assessed the performance of heat waves (HWs) in Korea in 2020. Case experiments during 2018-2020 were conducted to support the reliability of assessment, and the factors which affect predictability of the HWs were analyzed. Simulated expansion and retreat of the Tibetan High and North Pacific High during the 2020 HW had a good agreement with the analysis. However, the model showed significant cold biases in the maximum surface temperature. It was found that the temperature bias was highly related to underestimation of downward shortwave radiation at surface, which was linked to cloudiness. KIM tended to overestimate nighttime clouds that delayed the dissipation of cloud in the morning, which affected the shortage of downward solar radiation. The vertical profiles of temperature and moisture showed that cold bias and trapped moisture in the lower atmosphere produce favorable conditions for cloud formation over the Yellow Sea, which affected overestimation of cloud in downwind land. Sensitivity test was performed to reduce model bias, which was done by modulating moisture mixing parameter in the boundary layer scheme. Results indicated that the daytime temperature errors were reduced by increase in surface solar irradiance with enhanced cloud dissipation. This study suggested that not only the synoptic features but also the accuracy of low-level temperature and moisture condition played an important role in predicting the maximum temperature during the HWs in medium-range forecasts.

• 한국수소및신에너지학회논문집
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• 제12권4호
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• pp.257-265
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• 2001

Placing a hydrogen conducting, methanol impermeable metallic barrier like palladium (Pd) is a well-known method for preventing methanol crossover through solid polymer electrolyte for direct methanol fuel cells (DMFC). Applying a bias potential between the anode and the barrier can further develop this concept so that the hydrogen transfer rate is enhanced. Since hydrogen diffuses in Pd as atomic form while it moves through nafion electrolyte as ion, it has to be reduced or oxidized whenever it passes the interface formed by Pd and the electrolyte. We performed experiments to measure the hydrogen transport through the Pd membrane placed in Nafion electrolyte of hydrogen/oxygen fuel cell (PEMFC). Applying a bias potential between the hydrogen electrode of the cell and the Pd membrane facilitated the hydrogen passage through the Pd membrane. The results show that the cell current measured with the Pd membrane placed reached almost 40 % the value measured with the cell without Pd membrane. It was found that the current flown through the bias path is only a few percent of the cell current.

• 한국경영과학회지
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• 제21권3호
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• pp.159-174
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• 1996

Facing decision-making tasks, managers frequently make judgments, However, since managers are human beings, the fficiency of their judgments is limited. Two major sources of inefficiency in their judgments have been recognized : one is systematic deviations from normatively preferred decisions, so called bias or incorrect intuition, and the other is inconsistency in their judgments, i. e. erratic decision making variance. Rather than bias, variance is really expensive or damaging. Thus, if the inconsistency inmanagers judgments is removed, performance could be by far improved by virtue of the reduced random variance. One of the approaches to improve managerial judgment is to simply bring managers together by effectively moderating the random variance due to inconsistency. Focusing on combining judgments, this paper addresses many relevant issues such as why combining and how to combine judgments, and suggests methods and models to effectively aggregate subjective judgments, We conduct an experiment to validata the effectiveness of combining jugements over individual judgments. Various combining schemes are also evaluated in terms of their prective accuracy. Among them, mean bias based wighting scheme turns out the best. However, when available information is not enough to estimate the expertise of judges, simple and robust equal weighting might be more efficient and productive. This urges an imperative future research on the issue of how many and which ones to combine from a large set of experts.

• 응용통계연구
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• 제21권3호
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• pp.537-546
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• 2008

시계열자료 분석에 있어 주요 목적 중에 하나는 미래에 대한 예측 값을 추정하는 것이다. 이 논문에서는 정상자기회귀이동평균 모형에서 변환-역변환 방법을 이용하여 예측값을 구하는 과정에서 발생하는 문제에 대해 알아보고 회귀분석에서 제안되었던 smearing 추정방법을 시계열분석에서 사용할 수 있도록 붓스트랩을 이용하여 수정한 추정법을 소개한다. Yeo-Johnson 변환 (2000)을 이용한 KOSDAQ지수의 수익률 실증분석을 통해 기존에 사용되고 있는 방법의 문제점과 제안된 방법의 적절성에 대해 고찰해 보았다.

• Journal of Korean Vacuum Science & Technology
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• 제3권1호
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• pp.79-84
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• 1999

the photolithographic patterning on an indium-tin oxide (ITO) glass and the electro-phoretic deposition were combined for preparing the screen of the full-color field emission display(FED). the patterns with a pixel of 400$\mu\textrm{m}$ on the ITO-glass were made by etching the ITO with well-prepared etchant consisting of HCL, H2O, and HNO3. Electrophoretic method was carried out in order to deposit each spherical red (R), green(G), and blue (B) phosphor on the patterned ITO-glass. The process parameters such as bias voltage, salt concentration, and deposition time were optimized to achieve clear boundaries. It was found that the etching process of ITO combined with electrophoretic method was cost-effective, provided distinct pattern, and even reduced process steps compared with conventional processes. The application of reverse bias to the dormant electrodes while depositing the phosphors on the stripe pattern was found to be very critical for preventing the cross-contamination of each phosphor in a pixel.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.236-236
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• 2011

Silicon oxynitride (SiON) was deposited for gas barrier film on polyethylene terephthalate (PET) using octamethylycyclodisiloxane (Si4O4C8H24, OMCTS) precursor by plasma enhanced chemical vapor deposition (PECVD) at low temperature. The ion flux and substrate temperature were measured by oscilloscope and thermometer. The chemical bonding structure and barrier property of films were characterized by Fourier transform infrared (FT-IR) spectroscopy and the water vapor transmission rate (WVTR), respectively. The deposition rate of films increases with RF bias and nitrogen dilution due to increase of dissociated precursor and nitrogen ion incident to the substrate. In addition, we confirmed that the increase of nitrogen dilution and RF bias reduced WVTR of films. Because, on the basis of FT-IR analysis, the increase of the nitrogen gas flow rate and RF bias caused the increase of the C=N stretching vibration resulting in the decrease of macro and nano defects.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1222-1225
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• 1997

A gaseous oxygen detector has been developed in a configuration of Pd-$SnO_x$-$Si_3N_4$-$SiO_2$-Si-Al with highly resistive $SnO_x$ layer as the oxygen adsorptive element. In this paper, we present the characteristics of the device in response to oxygen adsoption/desorption under applied d.c. bias. Experimental results showed that the oxygen adsorptive response by the device was reduced significantly under a positive gate bias, for all experimental regions of $O_2$ partial pressure. On the other hand, the application of a negative gate bias increased the device's adsorptive response of oxgyen. A device model concerning this electroadsorption/desorption behavior of the device is provided.