• Title/Summary/Keyword: Sub-region

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Study on Experimental Fabrication of a New MOS Transistor for High Speed Device (새로운 고주파용 MOS 트랜지스터의 시작에 관한 연구)

  • 성영권;민남기;성만영
    • 전기의세계
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    • v.27 no.4
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    • pp.45-51
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    • 1978
  • A new method of realizing the field effect transistor with a sub-.mu. channel width is described. The sub-.mu. channel width is made possible by etching grooves into n$^{+}$ pn$^{[-10]}$ n$^{[-10]}$ structure and using p region at the wall for the channel region of the Metal-Oxide-Semiconductor transistor (MOST), or by diffusing two different types of impurities through the same diffusion mask and using p region at the surface for the channel region of MOST. When the drain voltage is increased at the pn$^{[-10]}$ drainjunction the depletion layer extends into the n$^{[-10]}$ region instead of into p region; this is also the secret of success to realize the sub-.mu. channel width. As the result of the experimental fabrication, a microwave MOST was obtained. The cut-off frequency was calculated to be 15.4 GHz by Linvill's power equation using the measured capacitances and transconductance.

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Cluster Analysis of Synoptic Scale Meteorological Characteristics on High PM10 Concentration Episodes in the Southeastern Part of Korean Peninsula (한반도 남동 지역에서 발생한 고농도 미세먼지 사례의 종관 기상학적 군집 특성 분석)

  • Chae, DaEun;Lee, Kangyeol;Lee, Soon-Hwan
    • Journal of the Korean earth science society
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    • v.41 no.5
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    • pp.447-458
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    • 2020
  • This study presents the K-means clustering analysis-based classification of the meteorological patterns affecting the occurrence of high PM10 concentration in the southeastern region of the Korean peninsula for the last five years (2014-2018). Regional differences in Busan, Ulsan, and Gyeongnam related to high PM10 episodes, were clarified through the statistical comparison study using synoptic scale meteorological elements using NCEP (National Centers for Environmental Prediction/FNL (Final Operational Global Analysis) re-analysis meteorological data. Meteorological patterns were classified into a total of five categories (C1-C5). The incidence of each cluster was 24.8% (C1), 21.3% (C2), 20.4% (C3), 17.3% (C4), and 16.2% (C5), respectively. The high PM10 concentration in the southeastern region resulted from long and short range transports (C1, C3, C5) from outside of the region, and the emissions (C2, C4) inside the region. In the high PM10 episodes in Busan, Ulsan, and Gyeongnam regions, meteorological characteristics such as different geopotential height and wind speed at 500 hPa in each cluster and the change in the location of high pressure over Korean Peninsula is strongly associated with the dispersion of PM10 around inventories in the region and the tendency of long-range transportation of PM10 emitted from outside of region.

Characteristics of Extremely High PM2.5 Episode and Emergency Reduction Measures Plan in Southeastern Region - Comparative Study in Busan vs. Seoul Metropolitan Area (II) (남동권 초고농도 미세먼지 발생 특성과 비상저감조치 - 수도권과 비교연구 (II))

  • Choi, Daniel;Heo, Gook-Young;Kim, Cheol-Hee
    • Journal of Environmental Science International
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    • v.30 no.10
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    • pp.789-802
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    • 2021
  • This study analyzed the characteristics of high PM2.5 episodes that meets the concentration criteria of Emergency Reduction Measures Plan (ERMP) in Busan during the 2015-2020, and compared with those in Seoul. As a first step, the CAPSS-2017 emission data was employed to analyze the emission differences between Busan and Seoul, and pointed out that Busan emission included the dominance of ship emissions (37.7%) among total PM2.5 city emissions, whereas fugitive PM2.5 emission was the highest in Seoul. These emission characteristics are indicating that the controlling action plan should be uniquely applied to cope with ERMP in each region. We selected extremely high PM2.5 episode days that meet the criteria of ERMP levels. In Busan, Ulsan, and Gyeongnam region, 15, 16, and 8 days of extremely high PM2.5 cases were found, respectively, whereas Seoul showed approximately doubling of occurrences with 37 cases. However, the occurrences in summer season indicated big differences between two cities: the proportion of summer-season occurrence was 13-25% in Busan, whereas no single case have occurred in Seoul. This is suggesting the needs of comprehensive summer emission reduction plan with focusing on sulfur reduction to effectively cope with the ERMP levels in summer in the southeastern region, including Busan.

Halo CME mass estimated by synthetic CMEs based on a full ice-cream cone model

  • Na, Hyeonock;Moon, Yong-Jae
    • The Bulletin of The Korean Astronomical Society
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    • v.46 no.1
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    • pp.43.1-43.1
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    • 2021
  • In this study, we suggest a new method to estimate the mass of a halo coronal mass ejection (CME) using synthetic CMEs. For this, we generate synthetic CMEs based on two assumptions: (1) the CME structure is a full ice-cream cone, (2) the CME electron density follows a power-law distribution (ρcme0r-n). The power-law exponent n is obtained by minimizing the root mean square error between the electron number density distributions of an observed CME and the corresponding synthetic CME at a position angle of the CME leading edge. By applying this methodology to 57 halo CMEs, we estimate two kinds of synthetic CME mass. One is a synthetic CME mass which considers only the observed CME region (Mcme1), the other is a synthetic CME mass which includes both the observed CME region and the occulted area larger than 4 solar radii (Mcme2). From these two cases, we derive conversion factors which are the ratio of a synthetic CME mass to an observed CME mass. The conversion factor for Mcme1 ranges from 1.4 to 3.0 and its average is 2.0. For Mcme2, the factor ranges from 1.8 to 5.0 with the average of 3.0. These results imply that the observed halo CME mass can be underestimated by about 2 times when we consider the observed CME region, and about 3 times when we consider the region including the occulted area. Interestingly these conversion factors have a very strong negative correlation with angular widths of halo CMEs.We also compare the results with the CME mass estimated from STEREO observations.

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A Deep Optical Survey of Young Stars in the Carina Nebula. I. UBVRI Photometric Data and Fundamental Parameters

  • Hyeonoh Hur;Beomdu Lim;Moo-Young Chun
    • Journal of The Korean Astronomical Society
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    • v.56 no.1
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    • pp.97-115
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    • 2023
  • We present the deep homogeneous UBV RI photometric data of 135,071 stars down to V ~ 23 mag and I ~ 22 mag toward the Carina Nebula. These stars are cross-matched with those from the previous surveys in the X-ray, near-infrared, and mid-infrared wavelengths as well as the Gaia Early Data Release 3 (EDR3). This master catalog allows us to select reliable members and determine the fundamental parameters distance, size, stellar density of stellar clusters in this star-forming region. We revisit the reddening toward the nebula using the optical and the near-infrared colors of early-type stars. The foreground reddening [E(B-V)fg] is determined to be 0.35 ± 0.02, and it seems to follow the standard reddening law. On the other hand, the total-to-selective extinction ratio of the intracluster medium (RV,cl) decreases from the central region (Trumpler 14 and 16, RV,cl ~ 4.5) to the northern region (Trumpler 15, RV,cl ~ 3.4). It implies that the central region is more dusty than the northern region. We find that the distance modulus of the Carina Nebula to be 11.9 ± 0.3 mag (d = 2.4 ± 0.35 kpc) using a zero-age main-sequence fitting method, which is in good agreement with that derived from the Gaia EDR3 parallaxes. We also present the catalog of 3,331 pre-main-sequence (PMS) members and 14,974 PMS candidates down to V ~ 22 mag based on spectrophotometric properties of young stars at infrared, optical, and X-ray wavelengths. From the spatial distribution of PMS members and PMS candidates, we confirm that the member selection is very reliable down to faint stars. Our data will have a legacy value for follow-up studies with different scientific purposes.

Design of Integrated-Optic Biosensor Based on the Evanescent-Field and Two-Horizontal Mode Power Coupling of Si3N4 Rib-Optical Waveguide (Si3N4 립-광도파로의 두-수평모드 파워결합과 소산파 기반 집적광학 바이오센서 설계)

  • Jung, Hongsik
    • Journal of Sensor Science and Technology
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    • v.29 no.3
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    • pp.172-179
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    • 2020
  • We studied an integrated-optic biosensor configuration that operates at a wavelength of 0.63 ㎛ based on the evanescent-wave and two horizontal mode power coupling of Si3N4 rib-optical waveguides formed on a Si/SiO2/Si3N4/SiO2 multilayer thin films. The sensor consists of a single-mode input waveguide, followed by a two-mode section which acts as the sensing region, and a Y-branch output for separating the two output waveguides. The coupling between the two propagating modes in the sensing region produces a periodically repeated optical power exchanges along the propagation. A light power was steered from one output channel to the other due to the change in the cladding layer (bio-material) refractive index, which affected the effective refractive index (phase-shift) of two modes through evanescent-wave. Waveguide analyses based on the rib optical waveguide dimensions were performed using various numerical computational software. Sensitivity values of 12~23 and 65~165 au/RIU, respectively for the width and length of 4 ㎛, and 3841.46 and 26250 ㎛ of the two-mode region corresponding to the refractive index range 1.36~1.43 and 1.398~1.41, respectively, were obtained.

Performance and Variation-Immunity Benefits of Segmented-Channel MOSFETs (SegFETs) Using HfO2 or SiO2 Trench Isolation

  • Nam, Hyohyun;Park, Seulki;Shin, Changhwan
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.4
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    • pp.427-435
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    • 2014
  • Segmented-channel MOSFETs (SegFETs) can achieve both good performance and variation robustness through the use of $HfO_2$ (a high-k material) to create the shallow trench isolation (STI) region and the very shallow trench isolation (VSTI) region in them. SegFETs with both an HTI region and a VSTI region (i.e., the STI region is filled with $HfO_2$, and the VSTI region is filled with $SiO_2$) can meet the device specifications for high-performance (HP) applications, whereas SegFETs with both an STI region and a VHTI region (i.e., the VSTI region is filled with $HfO_2$, and the STI region is filled with $SiO_2$) are best suited to low-standby power applications. AC analysis shows that the total capacitance of the gate ($C_{gg}$) is strongly affected by the materials in the STI and VSTI regions because of the fringing electric-field effect. This implies that the highest $C_{gg}$ value can be obtained in an HTI/VHTI SegFET. Lastly, the three-dimensional TCAD simulation results with three different random variation sources [e.g., line-edge roughness (LER), random dopant fluctuation (RDF), and work-function variation (WFV)] show that there is no significant dependence on the materials used in the STI or VSTI regions, because of the predominance of the WFV.

The Calculation Method of the Breakdown Voltage for the Drain Region with the Spherical Structure in High Voltage Analog CMOS (Spherical 구조를 갖는 고전압용 Analog CMOS의 Drain 역방향 항복전압의 계산 방법)

  • Lee, Un Gu
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.9
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    • pp.1255-1259
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    • 2013
  • A calculation method of the breakdown voltage for the Drain region with the spherical structure in high voltage analog CMOS is proposed. The Drain depletion region is divided into many sub-regions and the doping concentration of each sub-region is assumed to be constant. The field in each sub-region is calculated by the integration of the net charge and the breakdown voltage is calculated using the ionization integral method. The breakdown voltage calculated using the proposed method shows the maximum relative error of 3.3% compared with the result of the 2-dimensional device simulation using BANDIS.

Characteristics of Carbonaceous and Organic Components in PM2.5 over the Yellow Sea (서해상 PM2.5 내 탄소성분 및 유기성분의 화학적 특성)

  • Yoo, Ha Young;Kim, Ki Ae;An, Hyunjin;Lee, Yeonjung;Zihui, Teng;Yoo, Hee-Jung;Kim, Jeong Eun;Ko, Hee-Jung;Sung, Min-Young;Choi, Jin-Soo;Park, Jin-Soo;Lee, Ji Yi
    • Atmosphere
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    • v.31 no.3
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    • pp.267-282
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    • 2021
  • Characteristics of carbonaceous components and organic compounds in PM2.5 over the atmosphere of the Yellow Sea were investigated. PM2.5 samples were collected onboard the meteorological research vessel, GISANG 1, over the Yellow Sea during the YES-AQ campaign in 2018 and 2019, respectively. The average concentrations of carbonaceous components in this region were 2.59 ± 1.59 ㎍ m-3 for the OC, 0.24 ± 0.10 ㎍ m-3 for the EC, 2.14 ± 1.30 ㎍ m-3 for the WSOC and 1.17 ± 0.94 ㎍ m-3 for the HULIS-C, respectively. The total concentration of 56 organic compounds (ΣOCs) accounts for 10% of OC. The main group among organic compounds were dicarboxylic acids which account for 57% of ΣOCs, followed by n-alkanoic acids accounting for 34% of ΣOCs. In n-alkanoic acid distribution, hexanoic (C6:0) and octanoic (C8:0) acids which are low molecular weight n-alkanoic acids and known as emitted from marine biogenic activities were dominant in this region. Furthermore, non-HULIS-C fraction increased when the air mass originated from the marine region rather than the continental region. When the Asian dust episode was observed, the WISOC concentrations along with the levoglucosan were increased, while the haze episodes caused the increase of WSOC, HULIC-S and DCAs. In this study, we found that the components of carbonaceous and organic aerosols in PM2.5 over the Yellow Sea were changed with the specific air pollution episodes. It indicates that the physicochemical properties of PM2.5 can be changed by the air pollution episodes in this region.

Airborne In-situ Measurement of CO2 and CH4 in Korea: Case Study of Vertical Distribution Measured at Anmyeon-do in Winter (항공기를 이용한 온실가스 CO2와 CH4의 연속관측: 안면도 겨울철 연직분포사례 분석)

  • Li, Shanlan;Goo, Tae-Young;Moon, Hyejin;Labzovskii, Lev;Kenea, Samuel Takele;Oh, Young-Suk;Lee, Haeyoung;Byun, Young-Hwa
    • Atmosphere
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    • v.29 no.5
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    • pp.511-523
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    • 2019
  • A new Korean Meteorological Administration (KMA) airborne measurement platform has been established for regular observations for scientific purpose over South Korea since late 2017. CRDS G-2401m analyzer mounted on the King Air 350HW was used to continuous measurement of CO2, CH4 and CO mole fraction. The total uncertainty of measurements was estimated to be 0.07 ppm for CO2, 0.5 ppb for CH4, and 4.2 ppb for CO by combination of instrument precision, repeatability test simulated in-flight condition and water vapor correction uncertainty. The airborne vertical profile measurements were performed at a regional Global Atmosphere Watch (GAW) Anmyeon-do (AMY) station that belongs to the Total Carbon Column Observing Network (TCCON) and provides concurrent observations to the Greenhouse Gases Observing Satellite (GOSAT) overpasses. The vertical profile of CO2 shows clear altitude gradient, while the CH4 shows non-homogenous pattern in the free troposphere over Anmyeon-do. Vertically averaged CO2 at the altitude between 1.5 and 8.0km are lower than AMY surface background value about 7 ppm but higher than that observed in free troposphere of western pacific region about 4 ppm, respectively. CH4 shows lower level than those from ground GAW stations, comparable with flask airborne data that was taken in the western pacific region. Furthermore, this study shows that the combination of CH4 distribution in free troposphere and trajectory analysis, taking account of convective mixing, is a useful tool in investigating CH4 transport processes from tropical region to Korean region in winter season.