• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.250-250
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• 2011

Zinc oxide (ZnO) structures have great potential in many applications. Currently, the most commonly used method to grow ZnO nanostructres are the vapor transport method (VPT). The morphology of the ZnO structures largely related to the growth conditions, including growth temperature, distance between the substrate and source, and gas ambient. Previously ZnO nanosturecutres with high crystallinity were obtained at the growth temperature of 800$^{\circ}C$, in the argon and oxygen gas ambient. In this study, we report the properties of the ZnO nanostructures, which were synthesized on Au-catalyzed Si substrate by VPT, using a mixture of ZnO and graphite powders as source material under the different condition, including gas ratio of argon/oxygen and distance between substrate and source at the growth temperature of 800$^{\circ}C$. The structural and optical properties of the ZnO nanostructures were investigated by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and photoluminescence (PL).

• Applied Science and Convergence Technology
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• 제23권3호
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• pp.128-133
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• 2014

We study the ballistic spin transport properties in a two-dimensional electron gas system in the presence of magnetic barriers using a transfer matrix method. We concentrate on the size-effect of the magnetic barriers parallel to a two-dimensional electron gas plane. We calculate the transmission probability of the ballistic spin transport in the magnetic barrier structure while varying the width of the magnetic barriers. It is shown that resonant tunneling oscillation is affected by the width and height of the magnetic barriers sensitively as well as by the inter-spacing of the barriers. We also consider the effect of additional electrostatic modulation on the top of the magnetic barriers, which could enhance the current spin polarization. Because all-semiconductor-based devices are free from the resistance mismatch problem, a resonant tunneling structure using the two-dimensional electron gas system with electric-magnetic modulation would play an important role in future spintronics applications. From the results here, we provide information on the physical parameters of a device to produce well-defined spin-polarized current.

• 멤브레인
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• 제26권1호
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• pp.38-42
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• 2016

올레핀/파라핀 혼합 기체의 분리를 위한 올레핀 촉진 수송 분리막의 제조를 위해 amide 작용기를 가지며 glassy한 특성을 보이는 polyvinylpyrrolidone (PVP) 고분자를 분리막의 matrix로서 사용하였다. 분리막의 기체 투과 실험은 propylene과 propane 50 : 50의 부피비로 혼합된 기체를 사용하였고, bubble meter와 gas chromatography를 사용해 투과도와 선택도를 측정하였다. 또한 SEM image와 FT-IR을 통해 막의 특성을 조사하였다. 100시간의 장시간 성능 측정 결과 선택도는 약 15, 투과도는 약 1.3 GPU 이상을 각각 유지하였다. 기존의 poly(2-ethyl-2-oxazoline) $(POZ)/AgBF_4/Al(NO_3)_3$ 분리막과 비교함으로써, 고분자 matrix로서의 PVP 특성을 확인하였다.

• 한국막학회:학술대회논문집
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• 한국막학회 1991년도 추계 총회 및 학술발표회
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• pp.4-8
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• 1991

The characterization of pore properties (mean pore size and pore size distribution) of the active layer in a UF membrane is important not only in order to obtain information about the factors affecting pore formation during membrane manufacturing but also to understand deeply the mechanism of solute and solvent transport through pores. Many methods of characterizing quantitatively the pore properties of UF membranes have been suggested in the literature: solvent and gas flow measurement, bubble point determination, electron microscopy, gas adsorption/desorption measurement, rejection measurement etc. But most of these methods involve time-consuming procedures and involve some wellknown problems and uncertainties.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
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• pp.158-158
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• 2012

• 멤브레인
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• 제32권1호
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• pp.1-12
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• 2022

그래핀옥사이드는 우수한 물리적 특성 및 가공성으로 멤브레인 소재로 각광받고 있다. 특히, 이론적 예측과 실험적인 접근을 통해 그래핀옥사이드의 원자 수준의 얇은 두께, 뛰어난 기계적 강도, 높은 수준의 내화학성, 기공 생성이 가능한 2차원 구조 또는 기체 확산 유로 생성이 가능한 적층구조 등 멤브레인 소재로서 매우 유리한 특성들을 보유하고 있음이 밝혀졌다. 또한 그래핀옥사이드에서의 분자 투과 거동은 적층된 그래핀옥사이드 사이의 채널 크기에 따라 영향을 받는다는 것이 발견되었다. 그 후, 이러한 특성을 응용하여 그래핀옥사이드를 멤브레인 소재로 활용하기 위해 많은 연구가 집중적으로 진행되고 있다. 본 총설에서는 그래핀옥사이드의 고유 특성을 기반으로 멤브레인 분야로의 응용 가능성에 대하여 논하고자 한다.

• 한국연소학회지
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• 제12권1호
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• pp.38-47
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• 2007

The diversification of import districts of natural gas is trying to prepare an increase in the demand and price. The interchangeability of natural gases should be examined prior to supply to gas appliances, although compositional differences among natural gases are not large. The object of this study is to investigate numerically the thermodynamic and transport properties as well as information on combustion of 6 natural gases. Comparing the properties of BOG1 with those of standard gas, the maximum differences of heating value, Wobbe index, air-fuel ratio, and specific heat are 10%, 4%, 10% and 5.54%, respectively. That is, the BOG1 is required careful application. However, all gases except for BOG1 show the similar properties with standard gas. Finally, the combustion information such as flame temperature and burning velocity are examined. These results will provide the useful information related to the interchangeability of various natural gases in practical combustion appliances.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 학술대회 논문집 전문대학교육위원
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• pp.72-75
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• 2001

In this paper, we describe the results of a combined experimental theoretical study designed to understand and predict the dielectric properties of $SF_6$ and $SF_6+Ar$ mixtures. The electron transport, ionization, and attachment coefficients for pure $SF_6$ and gas mixtures containing $SF_6$ has been analysed over the E/N range $30{\sim}300Td$ by a two term Boltzrnann equation and by a Monte Carlo Simulation using a set of electron cross sections determined by other authors, experimentally the electron swarm parameters for 0.2% and 0.5% $SF_6+Ar$ mixtures were measured by time- of- flight method, The results show that the deduced electron drift velocities, the electron ionization or attachment coefficients, longitudinal and transverse diffusion coefficients and mean energy agree reasonably well with the experimental and theoretical for a rang of E/N values.

• 한국막학회:학술대회논문집
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• 한국막학회 2001년도 추계 총회 및 학술발표회(한국막학회)
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• pp.67-70
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• 2001

• 한국막학회:학술대회논문집
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• 한국막학회 2001년도 추계 총회 및 학술발표회(한국막학회)
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• pp.71-74
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• 2001