• 제목/요약/키워드: $DO_3SE$

검색결과 586건 처리시간 0.029초

Separation of Colloidal Particles by Osmotic Sink Field Flow Fractionation Using UF Hollow Fiber Membranes

  • Shin, Se-Jong;Min, Byoung-Ryul;Park, Jin-Won;Ahh, Ik-Sung;Lee, Kang-Taek;Lee, Jae-Hoon
    • Korean Membrane Journal
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    • 제3권1호
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    • pp.59-68
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    • 2001
  • Unlike existent field flow fractionation, new method, osmotic sink field flow fractionation is introduced and used ultrafiltration hollow fiber membranes as separation channel. This hollow fiber osmotic sink field flow fractionation is called HF-OSFFF. A theory that describes the retention, relaxation, resolution, plate number for the system, has been developed and experimentally verified by separation model of po1ystyrene latex beads. At external field, it is measured that radial flow rates change according to various concentrations of PEG solutions. Concentration of PEG solution vs. radial flow rate is a linear relation. For diameter distribution of unknown polymer sample, HF-OSFFF compared with the commercial capillary hydrodynamic flow fractionation (CHDF).

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Pt-ZnO Schottky 구조 제작 및 자외선 반응 특성

  • 유승용;유한태;이영민;윤형도;이세준;김득영
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2009년도 제38회 동계학술대회 초록집
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    • pp.182-182
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    • 2010
  • 본 연구에서는 Pt 배면전극에 다양한 조건에서의 ZnO를 성장하여 Schottky 구조를 제작, 접합 특성 및 자외선 검출 특성을 연구하였다. $Al_2O_3$ 기판에 Mirror-like하며 고결정성을 갖는 Pt(111) 배면전극을 형성 후, ZnO 박막의 성장 조건에 따른 접합 특성을 확인하기 위하여 기판온도와 산소분압을 각각 $400{\sim}600^{\circ}C$ ($50^{\circ}C$ 단계), 0~60 sccm (15 sccm 단계)로 성장하였다. 이에 따른 구조적 특성변화를 확인하기 위하여 주사전자현미경 및 X선 회절 특성을 분석하였으며, 전류-전압 특성 곡선을 분석을 통하여 최적의 Schottky contact 형성을 위한 ZnO 성장조건을 규명하고자 하였다. $H_2O_2$를 이용한 표면처리와 Rapid Thermal Annealing (RTA)를 이용한 열처리 과정을 통하여 표면 처리 전 후의 전기적 특성과 광학적 특성의 변화를 비교 분석하였다. 또한 Ohmic 접촉으로 상부전극을 형성, ZnO Schottky photodiode 구조를 제작하여 UV-A, B, C 영역에 따른 UV반응 특성을 분석하였다.

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Chemisorption and orientation of Selenopheneon Si(100)-$2{\times}1$

  • Lee, Han-Koo;Kim, Ki-Jeong;Kim, Hyeong-Do;Shin, Hyun-Joon;Kim, Bong-Soo
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2009년도 제38회 동계학술대회 초록집
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    • pp.372-372
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    • 2010
  • We have investigated adsorption of selenophene on Si(100) at room temperature using high resolution photoemission spectroscopy (HRPES) and near edge X-ray absorption fine structure (NEXAFS) in the partial electron yield (PEY) mode. The Si 2p, C 1s, Se 3d spectra of selenophene on Si(100) show that selenophene is nondissociatively chemisorbed on Si(100)-$2{\times}1$ through [2+2] cycloaddition. NEXAFS has been conducted to characterize the adsorption geometry of selenophene on Si(100). Since the $\pi^*$ orbital of C=C bond show good angular dependence in carbon K-edge NEXAFS spectra, the angle $53{\pm}5^{\circ}$ determined from NEXAFS spectra. This majority structure is consistent with the [2+2] cycloaddition of selenophene to the dimer of the Si(100)-$2{\times}1$ surface.

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Measurement of Focal Length for Off-axis Optical Systems

  • Choe, Se-woon;Ryu, Jaemyung
    • Current Optics and Photonics
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    • 제5권4호
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    • pp.402-408
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    • 2021
  • An off-axis system refers to an optical system in which the optical axis and normal vector at the vertex of each surface do not match. The most important specification in an optical system is its focal length. Among the various methods for measuring the focal length, the most suitable method for the off-axis system is the method that adopts magnification. However, head-mounted display (HMD) optics must be measured while considering the virtual image distance, which is not infinity owing to product characteristics. For the virtual image distance, a camera with a focusing function was used. By measuring HMD optics via this magnification method, the error generated in this measurement was 0.68% of the HMD's focal length, which is within the 1%-3% range of the conventionally permitted design error for the focal length allowed at the optical design stage. Therefore, it can be verified that the measurement accuracy of the method proposed in this study is sufficiently feasible in practice.

CompressAI 를 활용한 객체 검출 네트워크 피쳐 맵 압축 (Object Detection Network Feature Map Compression using CompressAI)

  • 도지훈;이주영;김연희;최진수;정세윤
    • 한국방송∙미디어공학회:학술대회논문집
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    • 한국방송∙미디어공학회 2021년도 하계학술대회
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    • pp.7-9
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    • 2021
  • 본 논문은 Detectron2 [1]에서 지원하는 객체 검출 임무 수행 네트워크의 과정 중에서 추출한 피쳐 맵을 신경망 기반으로 압축하는 방법을 제안한다. 이를 위해, 신경 망 기반 영상 압축을 지원하는 공개 소프트웨어인 CompressAI [2] 모델 중 하나인 bmshj2018-hyperprior 의 압축 네트워크를 활용하여 임무 수행 네트워크의 과정 중 스탬 레이어(stem layer)에서 추출된 피쳐 맵을 압축하도록 학습시켰다. 또한, 압축 네트워크의 입력 피쳐 맵의 너비와 높이 크기가 64 의 배수가 되도록 객체 검출 네트워크의 입력 영상 보간 값을 조정하는 방법도 제안한다. 제안하는 신경망 기반 피쳐 맵 압축 방법은 피쳐 맵을 최근 표준이 완료된 차세대 압축 표준 방법인 VVC(Versatile Video Coding, [3])로 압축한 결과에 비해 큰 성능 향상을 보이고, VCM 앵커와 유사한 성능을 보인다.

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유색 농산물 중 안토시아닌과 폴리페놀 함량 비교 연구 (A Comparative Study on Anthocyanin and Polyphenol Contents in Colored Agricultural Products)

  • 정일형;오문석;전종섭;김한택;홍세라;박광희;윤미혜
    • 한국식품위생안전성학회지
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    • 제32권5호
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    • pp.371-380
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    • 2017
  • 본 연구에서는 인터넷 쇼핑몰에서 유통되는 컬러푸드 중 블랙푸드 76건을 대상으로 폴리페놀 17종 및 안토시아닌 5종을 동일한 전처리 방법으로 HPLC, HPLC-MS/MS 분석하여 정량 및 정성시험을 실시하였다. 분석대상 폴리페놀은 gallic acid, protocatechuic acid, chlorogenic acid, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, t-ferulic acid, t-cinnamic acid 등 9종의 phenolic acid와 (+)catechin, syringic aldehyde, rutin, epicatechin gallate, naringin, luteolin, naringenin, kaempferol 등 8종의 flavonoid로 총 17종의 폴리페놀을 동시분석 하였고, 안토시아닌은 delphinidin-3-glucoside, delphinidin-3-rutinoside, cyanidin-3-galactoside, cyanidin-3-glucoside, cyanidin-3-arabinoside 등 5종을 동시분석 하였다. 폴리페놀 17종의 총 함량은 서리태 $255.1{\pm}7.5{\mu}g/g$, 서목태 $275.8{\pm}5.3{\mu}g/g$, 흑미 $78.5{\pm}4.6{\mu}g/g$, 흑임자 $75.8{\pm}3.2{\mu}g/g$, 블루베리 $143.3{\pm}5.5{\mu}g/g$, 아로니아 $195.2{\pm}4.9{\mu}g/g$, 블랙커런트 $131.6{\pm}3.2{\mu}g/g$로 나타나 서목태 > 서리태 > 아로니아 > 블루베리 > 블랙커런트 > 흑미 > 흑임자 순으로 높은 함량을 나타냈다. 안토시아닌 5종의 총 함량은 서리태 $82.4{\pm}17.2{\mu}g/g$, 서목태 $95.2{\pm}6.1{\mu}g/g$, 흑미 $74.1{\pm}9.7{\mu}g/g$, 흑임자 불검출, 블루베리 $110.8{\pm}1.9{\mu}g/g$, 아로니아 $218.9{\pm}6.1{\mu}g/g$, 블랙커런트 $209.7{\pm}4.0{\mu}g/g$로 나타나 아로니아 > 블랙커런트 > 블루베리 > 서목태 > 서리태 > 흑미 순으로 높은 함량을 나타났다. 본 실험결과 폴리페놀은 서목태, 안토시아닌은 아로니아가 가장 높은 함량을 나타내었으며 향후 유색 농산물을 활용한 기능식품 개발이 필요한 것으로 판단된다.

진공증발원 시스템을 이용한 CIGS 박막의 특성평가에 관한 연구 (Properties of CIGS thin film developed with evaporation system)

  • 김은도;정예슬;정다운;엄기석;황도원;조성진
    • 한국신재생에너지학회:학술대회논문집
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    • 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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    • pp.85.1-85.1
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    • 2010
  • $Cu(In,Ga)Se_2$ (CIGS) thin film solar cell is currently 19.5% higher efficiency and developing a large area technology. The structure of CIGS solar cell that make five unit layers as back contact, light absorption, buffer, front transparent conducting electrode and antireflection to make them sequentially forming. Materials and various compositions of thin film unit which also manufacture a variety method used by the physical and chemical method for CIGS solar cell. The construction and performance test of evaporator for CIGS thin film solar cell has been done. The vapor pressures were changed by using vapor flux meter. The vapor pressure were copper (Cu) $2.1{\times}10^{-7}{\sim}3.0{\times}10^{-7}$ Torr, indium (In) $8.0{\times}10^{-7}{\sim}9.0{\times}10^{-7}$ Torr, gallium (Ga) $1.4{\times}10^{-7}{\sim}2.8{\times}10^{-7}$ Torr, and selenium (Se) $2.1{\times}10^{-6}{\sim}3.2{\times}10^{-6}$ Torr, respectively. The characteristics of the CIGS thin film was investigated by using X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and photoluminescence (PL) spectroscopy using a He-Ne laser. In PL spectrum, temperature dependencies of PL spectra were measured at 1137 nm wavelength.

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질화규소의 Laser-Assisted Machining 공정에 관한 연구 (A Study on Laser-Assisted Machining Process of Silicon Nitride)

  • 임세환;이제훈;신동식;김종도;김주현
    • 한국정밀공학회지
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    • 제26권5호
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    • pp.48-56
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    • 2009
  • In this paper, laser-assisted machining(LAM) has been employed to machine hot isostatically pressed (HIPed) Si3N4 work pieces. Due to little residual flaws and porosity, HIPed $Si_3N_4$ work pieces are more difficult to machine compared to normally sintered $Si_3N_4$ workpieces. In LAM, the intense energy of laser was used to enhance machinability by locally heating the workpiece and thus reducing yield strength. In experiments, the laser power ranges from 200W to 800W and the diameter of work pieces is 16mm. While machining, the surface temperature was kept nearly constant by laser heating except for a short period of rise time of max. 58 seconds. Results showed as feed rate increases the surface temperature of $Si_3N_4$ workpieces decreases slightly, whereas the effect of depth of cut is disregardable. With a laser power of 800W, achievable maximal depth of cut as 0.7mm and feed rate was 0.03mm/rev.

Ultraviolet Photoelectron spectroscopy Study of Colossal Magnetoresistive $La_{0.7-x}P_rxCa_{0.3}MnO_3$

  • Lee, Chang-Won;Hoon Koh;Noh, Han-Jin;Park, Jong-Hyurk;Kim, Hyung-Do;Moonsup Han;Oh, Se-Jung;Eom, dai-Jin;Noh, Tae-Won
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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    • pp.172-172
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    • 1999
  • Perovskite Manganese Oxide has been intensively investigated since the discovery of the colossal magnetoresistive(CMR) effect. In this paper, we studied the effect of temperature dependence and various doping dependence of rare earth site ions of La0.7-xPrxCa0.3MnO3 series using Ultraviolet Photoelectron spectroscopy(UPS). They show unusual temperature dependent features and the doped rare earth ions seem to affect the electron-phonon coupling strongly. We found clear evidence of metal-insulator transition from the spectral density at the Fermi level. but the transition temperature is lower than that deduced from transport measurements. Also we found that the spectral features change as time goes on implying that the surface of these materials is somewhat unstable in the vacuum. We can conclude from these results that the surface oxygen atoms correlated to the hopping electrons can escape from the material into the vacuum and that the surface state of these material is different from the bulk state.

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