• 천문학회보
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• 제42권2호
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• pp.66.2-66.2
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• 2017

The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administrative (NASA) and install it on the International Space Station (ISS). The coronagraph is an externally occulted one stage coronagraph with a field of view from 2.5 to 15 solar radii. The observation wavelength is approximately 400 nm where strong Fraunhofer absorption lines from the photosphere are scattered by coronal electrons. Photometric filter observation around this band enables the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with the high time cadence (< 12 min) of corona images to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in 2017 August for the filter system and to perform a stratospheric balloon experiment in 2019 for the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g. coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.

• Applied Microscopy
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• 제35권4호
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• pp.98-104
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• 2005

초고전압 투과전자현미경 (HVEM)에 장착된 postcolumn 방식의 HV-GIF (high voltage gatan image filter)의 영상기록 장치인 HV-MSC (high voltage multi-scan CCD, $1024{\times}1024$픽셀) 카메라의 결상영역은 현미경 최소 관찰 배율인 2,000배에서 $0.43{\mu}m^2$로서 동일 배율에서 필름 기록영역($2000{\mu}m^2$)에 비해 약 0.02%에 해당하는 매우 적은 영역이다. 이러한 결상 영역 제한성을 개선하고자 투사렌즈 전류조절 기법을 도입하였으며 본 연구의 결과로 HV-MSC의 결상영역은 $112{\mu}m^2$로 비약적으로 증가하였다. 이는 약 8,800배에서 필름으로 기록할 수 있는 영역과 동일하였다. 이와 더불어 투사렌즈 조절에 따른 이미지 변형정도를 약 5%이하까지 허용하고 8,800배 이상에서 필름 기록영역과 동일한 HV-MSC 결상영역을 확보할 수 있는 실험적인 참조곡선을 고안하였다.

• 천문학회지
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• 제50권5호
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• pp.139-149
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• 2017

The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administration (NASA) and to install it on the International Space Station (ISS). The coronagraph is an externally occulted one-stage coronagraph with a field of view from 3 to 15 solar radii. The observation wavelength is approximately 400 nm, where strong Fraunhofer absorption lines from the photosphere experience thermal broadening and Doppler shift through scattering by coronal electrons. Photometric filter observations around this band enable the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with a high time cadence (<12 min) of corona images used to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in August 2017 with the filter system and to perform a stratospheric balloon experiment in 2019 with the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g., coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.

• 폴리머
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• 제35권6호
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• pp.553-557
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• 2011

전기방사법을 이용하여 폴리(비닐 알코올)(poly(vinyl alcohol), PVA)/수분산 폴리우레탄(waterborne polyurethane, WBPU)/montmorillonite clay(MMT) 나노복합섬유를 제조하고 특성을 분석하였다. Scanning electron microscopy(SEM), transmission electron microscopy(TEM), X선 회절, thermal gravimetric analyzer(TGA) 의 분석장비들을 이용하여 제조된 나노복합섬유의 형태와 구조적, 열적특성을 확인한 결과, 평균직경이 600~900 nm인 나노복합섬유들이 성공적으로 제조되었으며, MMT가 나노섬유 내에 완전박리되어 기존의 고분자 나노섬유에 비해 열적성질이 향상되었음을 확인할 수 있었다. 본 연구를 통해 제조된 나노복합섬유는 친수성이고 생체친화적인 재료들을 이용하여 제조되었으며, 의료 분야를 비롯하여 의류 및 산업용 코팅제, 필터 등의 분야로 이용이 가능할 것으로 보인다.

• 한국염색가공학회지
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• 제34권1호
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• pp.20-26
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• 2022

Centrifugal spinning is an emerging technique for fabricating micro-to-nano-fibers in recent years. To obtain fibers with the desired size and morphology, it is necessary to configure and optimize the parameters used in centrifugal spinning. In this study, it was controlled by changing the solution's concentration (7.5, 10, and 12.5 wt.%) and disk's rotational velocity (6,000, 8,000, and 10,000 rpm) to prepare centrifugal spun nano-filter. The morphological property, air permeability, and dust collection efficiency of the PVA/PP bi-layer nanoweb prepared by centrifugal spun PVA on the PP micron nonwoven substrate are studied using a field emission scanning electron microscope, an air permeability tester, and a filter tester equipment, and the analysis results indicate that it is suitable as a nano-filter when the concentration of PVA solution is 10 wt.% and the rotational velocity of the disk is 8,000 rpm. The resultant reduced diameter and uniform fibers also proved that an excellent dust collection efficiency filter could be made.

• 한국지하수토양환경학회지:지하수토양환경
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• 제11권2호
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• pp.22-37
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• 2006

생물벽체(biobarrier) 또는 원위치 미생물 필터(in situ microbial filter) 기술을 이용한 염소계 유기용매로 오염된 지하수의 복원 가능성을 회분식 실험을 통하여 살펴보았다. PCE의 환원성 탈염소화의 효율과 속도는 수소 농도에 의존하는 것으로 알려져 있다. 본 연구에서는 분변토와 토탄을 생물벽체로 이용한 PCE의 환원성 탈염소화시 전자공여체의 영향을 살펴보았다. 유기산(lactate, butyrate benzoate)과 yeast extract, 비타민 $B_{12}$가 PCE의 환원성 탈염소화에 미치는 영향을 조사하였다. 생물벽체 담체 비존재시, 전자공여체를 투여하지 않은 control 실험에 비해, 전자공여체의 첨가는 PCE의 탈염소화 속도를 촉진하였다. 전자공여체를 투여한 실험 중에서 lactate 또는 lactate/benzoate를 수소 공여체(hydrogen donor)로 첨가된 경우, 탈염소화 속도가 가장 빨랐다($k_1=0.0260{\sim}0.0266\;day^{-1}$). 분변토를 생물벽체로 사용한 경우, lactate/benzoate 첨가시 탈염소화 속도가 가장 빨랐으며, 겉보기 1차 분해속도상수($k_1$)는 $0.0849day^{-1}$였다. 반면, Pahokee peat을 생물벽체로 사용하였을 경우, butyrate 또는 lactate의 첨가시 탈염소화 속도가 가장 빨랐으며 $k_1$ 값은 각각 0.1092, $0.1067\;day^{-1}$로 나타났다. 본 연구결과로부터 분변토 또는 토탄을 원위치 생물벽체로 사용하여 염소계 유기용매로 오염된 지하수 처리의 잠재적인 응용 가능성을 알 수 있었다.

• 센서학회지
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• 제16권3호
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• pp.240-245
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• 2007

AlN thin film for SAW filter application was deposited on (100) silicon, sapphire, $Si_{3}N_{4}$/Si, and $Al_{2}O_{3}$/Si substrates by reactive magnetron sputtering method, respectively. The structural characteristics were dependent on the structure of substrates. Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Atomic Force Microscope (AFM) have been used to analyze structural properties and preferred orientation of AlN thin films. Preferred orientation and SAW characteristic of AlN were improved by insertion of $Al_{2}O_{3}$ buffer layer. Insertion loss of SAW devices using AlN/Si and AlN/$Al_{2}O_{3}$/Si were about 33.27 dB and 30.20 dB, respectively.

• 한국산학기술학회논문지
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• 제1권1호
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• pp.33-36
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• 2000

대형 진공증착기내에 대형 피코팅물 고정대를 방사형으로 배치고 대용량의 피코팅물이 균일하게 코팅되도록 공전과 자전을 병행하도록 하여, 1회 진공으로 피코팅물의 양면을 동시에 코팅하므로 증착시간을 절약하고 전력소비를 줄일 수 있으며 대기중 이물질에 의한 오염방지를 할 수 있었다. 내부에 이중 전자빔을 설치하여 자동 다층막 증착이 가능하며, 유효증착면적을 크게 할 수 있었다. 이런 장치를 이용하여 증착 시간의 30% 단축, 작업 생산성 50% 향상과 아울러 증착막의 전도막 특성도 향상되었으며 증착막의 균일도도 향상되었다. 증착막의 광학적 특성인 반사방지 투과율 특성도 향상되었다.

• The Korean Journal of Ceramics
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• 제3권2호
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• pp.110-115
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• 1997

Li-doped ZnO films were prepared on Corning 1737 glass substrate by an rf magnetron sputtering technique using ZnO targets with various $Li_2CO_3$ contents ranging from 0 to 10 mol%. The effects of Li doping on the crystallinity and electrical properties of ZnO films were studied for their SAW filter applications. The film resistivity largely increased without suppressing the c-axis orientation and crystallinity with a small addition of Li. Heat treatment of the film at 40$0^{\circ}C$ induced that the film resistivity, c-axis orientation and crystallinity slightly increased. However, heat treatment of the film at 50$0^{\circ}C$ resulted in much lower resistivity than that of as-deposited film due to the increase of electron concentration caused by the evaporationof Li atoms from the ZnO film. Large addition of Li into the ZnO film rather diminished the film resistivity and suppressed the c-axis growth. It was concluded that a small doping of Li into the ZnO film and heat treatment at 40$0^{\circ}C$ caused the film resistivity to be high enough for SAW filter applications without suppression of the c-axis orientation and crystallinity.

• 대한기계학회논문집B
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• 제28권9호
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• pp.1117-1123
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• 2004

The characteristics of soot near the soot inception point for an ethene-air flame was carried out in a WSR (well-stirred reactor). The new sampling tool like the temperature controlled filter system was introduced to minimize the condensation during sampling. The new analysis tools applied include the real time size distribution analysis with the Nano-DMA, particle size by transmission electron microscopy, C/H analysis, g filter analysis, and thermogravimetric analysis using both non-oxidative and oxidative pyrolysis. The WSR can generate young soot particles that can be collected and examined to gain insight into inception. For the current conditions, soot does not form for ${\Phi}$=1.9, inception occurs at or before ${\Phi}$=2.0, and inception combined with soot surface growth and/or coagulation occurs for ${\Phi}$=2.1. The filter samples for ${\Phi}$=1.9 are composed of volatile compounds that evolve at relatively low temperatures when heated in the presence or absence of O$_2$. The samples collected from the WSR at ${\Phi}$=2.0 and ${\Phi}$=2.1 are precursor-like in morphology and size. They have higher C/H ratios and lower organic percentages than precursor particles, but they are clearly not fully carbonized soot. The WSR PAH distribution is similar to that in young soot from inverse flames.