• Journal of Sensor Science and Technology
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• v.4 no.2
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• pp.51-57
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• 1995

Indium Tin Oxide (ITO) thin films have been fabricated by the rf magnetron sputtering technique with a target of a mixture $In_{2}O_{3}$ (90mol%) and $SnO_{2}$ (10mol%). We prepared ITO thin films with substrate temperature 100, 200, 300, 400, $500^{\circ}C$ and post-annealing temperature 300, 400, $500^{\circ}C$. And we analyzed X -ray diffraction patterns, electrical properties, transmission spectra and SEM photographs. As a result, the crystallinity, electrical conductivity and transmittance of ITO thin films were improved with increasing substrate temperature. But, as increasing post-annealing temperature in air, conductivity of the film was decreased. When the ITO thin film was fabricated with substrate temperature of $500^{\circ}C$ and thickness of $3000{\AA}$, its resistivity and transmittance were about $2{\times}10^{-4}{\Omega}cm$ and 85% or more, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1584-1589
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• 2014

This study analyzed CT values of radiolucent and radiopaque materials by energy region after selecting radiolucent and radiopaque materials at random using GE's DECT((Dual Energy Com-puted Tomography) at S University Hospital located in Gyeonggi-province from July through August in 2013. Besides, it drew out the most analogous energy region to the value of 120kVp CT, which is applied to existing SECT(Single Energy Computed Tomography), by utilizing the analysis method of CT values and tried to find out the most useful and appropriate materials when contrast was applied within visible area in clinical application. As a result, there was little decrease of CT value after 90KeV in the case of materials with low density and high moisture content such as normal saline, methyl-cellulose and gels used in ultra-sonic waves test; energy does not influence much on materials with extremely low or high density such as air and contrast medium; methyl-cellulose and gels used in ultra-sonic waves test are considered to be the most useful materials for clinical applications.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4B
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• pp.421-428
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• 2008

For last decades, the rapid coastal erosion process spreading along Korean peninsular has become a nuisance especially for tourism and local economy. Global warming and sea-level rise demand persistently new coastal protection strategies against the conventional methods using armored structures. In a view of this, Kweon et al. (2007) has proposed a new type of horizontal steel plates for an ideal candidate as eco-friendly detached breakwater systems for global warming era. The breakwater is composed of piles and horizontal porous plates that was devised for the optimized blockage effects and wave energy dissipations. This system provides outstanding performances as wave barrier and added advantages such as a rapid installation, an easy relocation, a perfect water circulation for the stagnation of pollutions in sheltered regions. The present experimental study focuses on the performance evaluations of the proposed system in wind wave conditions as a wave dissipator and reflector. The reflection, transmission, and energy dissipation of the random waves has been discussed in detail based on a newly proposed relation between wave steepness and a plate width normalized by wave length that are major factors affecting the wave transmission.

• Membrane Journal
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• v.16 no.2
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• pp.115-122
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• 2006

In this study the membrane preparation and water vapor permeation of the hydrophilic polymer materials, polyaminosiloxane and polyhydroxylsiloxane, used as the coating materials for the preparation of asymmetric flat and hollow fiber membranes were investigated. And the water vapor permeation towards air permeation and their permselectivity were intensively studied for the resulting Resin A/Resin C (coupling agent) and Resin B/Resin C membranes. The water vapor permeability for 3 wt% Resin C introduced into Resin A (Resin A/Resin C) membrane was higher than for 1 and 5 wt% membranes and also water vapor permeability increased with increasing operating temperatures. In addition, at this content of 3 wt% Resin C, the absorption capability became maximum through dynamic equilibrium absorption experiment. Water vapor permeability, 43578 Barrer (1 Barrer = $10^{-10}cm^3(STP){\cdot}cm/cm^2{\cdot}s{\cdot}cmHg$) and 53000 Barrer, and the selectivity of $P(H_2O)P(Air)$, 101.3 and 102.6 were shown at 25 and $35^{\circ}C$, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1991.04a
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• pp.47-52
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• 1991

주거환경을 침해하는 소음의 주된 요인은 가전제품으로서, 대부분의 가전제 품은 전기모터에 의해 구동된다. 가전제품을 작동시키는 전기모터는 가전제 품에 기진력을 주는 한편 공기중으로 소음을 방사함으로서 조용한 주거환경 을 해치게 된다. 따라서 조용하고 쾌적한 주거환경 확보를 위해서는 가전제 품용 구동모터의 소음을 효과적으로 차단 또는 감소해야 한다. 모터의 소음 원은 그 모터의 종류와 형태에 따라 약간씩은 다를 수 있으나 일반적으로 크게 기계적 소음, 공기 역학적 소음, 전자기 소음, 열/전기 화학적 소음 등 으로 분류된다. 이들 중 모터의 소음에 큰 영향을 주는 것은 기계적 소음, 공기 역학적 소음, 전자기 소음이며 열/전기 화학적 소음은 매우 작은 편이 다. 또한 공기 역학적 소음은 모터에 팬이 부착될 경우에만 큰 문제가 될 뿐 이며, 팬이 부착되지 않을 경우에는 기계적 소음과 전자기 소음이 주된 소음 원이 된다. 기계적 소음과 전자기 소음은 어느 것이 주된 소음원인지는 일반 적으로 잘 알 수 없기 때문에, 개별적인 연구와 실험을 통하여 파악해야 한 다. 기계적 소음은 주로 회전자의 불균형 회전에 의한 진동 및 그로 인한 외 부 프레임의 진동으로 대별되며, 전자기 소음은 주로 공급(Air-Gap)에서의 투과파(permeance wave)와 기자력(magneto-motive force)에 의한 반지름 방향의 힘에 의해 주로 발생된다. 본 연구에서는 기계적 소음과 전자기 소음 중 모터 소음에 영향이 큰 소음원을 판별해 내고 모델 실험을 통하여 감소 방안을 검토하였다.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1168-1173
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• 2005

Pilot scale vertical-type membrane bioreactor was operated to examine the effect of $FeCl_3$ injection on the removal of organics, nitrogen and phosphorous, and additionally trans-membrane pressure (TMP) was observed. The membrane type was hollow fiber membrane with pore size of $0.25\;{\mu}m$, and the material was polytetrafluoroethylene (PTFE). The membrane permeate was continuously removed by a pump under a constant flux ($25\;L/m^2/h$). Air back-flushing technique were adopted to reduce fouling. As a result, TMP was increased more slowly than that of the operation without air back-flushing, During long-term operation, approximately 310 days, the injection of $FeCl_3$ was effective not only in removing phosphorous chemically but also in reducing TMP increase. Furthermore, while the average COD and T-N concentration of the effluent without $FeCl_3$ injection was 14.3 mg/L and 6.0 mg/L respectively, that of effluent with $FeCl_3$ was 11.3 mg/L and 6.0 mg/L respectively, which confirmed the effects of $FeCl_3$.

• Membrane Journal
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• v.29 no.3
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• pp.147-154
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• 2019

The permeate flux increments of a natural convection instability flow (NCIF) caused by the change of inclined angles ($0{\sim}180^{\circ}$) to gravity of the commercial membrane module were tested in the dead-end membrane filtration of BSA protein solution. The NCIF are more generated as the inclined angle increased from $0^{\circ}$ to $180^{\circ}$, and the occurred NCIF enhances permeate flux. However, the commercial module can only generate NCIF by completely removing the air gap in module. Since the custom design module designed in this study is permeated in a crossward direction ($90^{\circ}$), NCIF is always generated even if there is the air gap in module. The results of membrane filtration of BSA and dextran solutions using a custom design module showed that the flux in the crossward direction is increased to about 3.8 times for BSA solution and 1.8 times for dextran solution after two hours of operation due to the occurrence of NCIF. Also, NCIF generation is continued during 20 hours filtration of BSA solution, increasing the permeate flux to about 7.5 times. Since the custom design module with a permeation in the crossward direction and NCIF is always generated within the module, so it is possible to expect an increase in permeate flux due to the suppression of fouling formation, and thus to be utilized as a superb dead-end membrane module.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.699-706
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• 2018

The permeation properties of plasma polymer membranes were studied for permanent gases such as He, $H_2$, $O_2$, $N_2$, $CH_4$ and condensable vapors such as $CO_2$, $C_2H_4$, $C_3H_8$. The plasma polymers were prepared by the discharge of microwave or radiofrequency(RF) wave. Hexamethyldisiloxane (HMDS) vapor was used as a monomer for plasma polymerization. In HMDS plasma-polymerized membranes prepared under microwave discharge, the permeability coefficient was dependent of the kinetic molecular diameter of the permeate gases. Additionally the membranes showed higher $O_2/N_2$ permselectivity compared to the plasma polymers from radiofrequency discharge. On the contrary, in the HMDS plasma-polymerized membranes prepared under radiofrequency discharge, the permeability coefficient was dependent of the critical temperature of the permeant gases. The membranes showed high selectivities of $C_2H_4$ and $C_3H_8$ over $N_2$. The permeability coefficient of plasma polymerized membranes prepared under microwave discharge was dependent of the molecular diameter of permeant gases because of high crosslinking density of the membrane. However, the crosslinking density of the plasma polymerized membranes prepared under RF discharge was lower because the energy density of RF wave is weaker than that of microwave. Hence, the permeability of RF plasma polymerized membranes became dependent of the critical temperature rather than molecular diameter of the gases.

• Journal of the Korean Wood Science and Technology
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• v.33 no.6 s.134
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• pp.17-24
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• 2005

Korean pine (Pinus koraiensis Sieb.et Zucc.) boards of 30 mm thickness were treated by steaming and four different drying methods. Small specimens were taken from the sapwoods of the treated boards and their longitudinal liquid permeability was measured according to Darcy's law. The specimens were also extracted with alcohol and aceton solutions to examine the mechanism of liquid flow in wood. It was observed that specific permeability drastically decreases with measurement time, resulting in violation of Darcy's law. It may be due to that air bubbles formed under vacuum block flow paths in resin canals. The average specific permeabilities of non-extracted and extracted specimens are different from one treatment to another. It is supposed that the properties of residual resin in resin canals change depending on the conditions of treatments. Anatomical examination was conducted with a scanning electron microscope.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.468-468
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• 2008

IZO(Indium zinc oxide) 박막은 화학적으로 안정하면서, 가시광 영역 (380~780 nm)에서 80% 이상의 높은 투과도와 낮은 전기비저항, 3.5 eV 이상의 넓은 밴드갭 특성을 가진다. IZO 박막의 이러한 특성 때문에 평판표시소자 (Flat Panel Display; FPD) 및 태양전지와 같은 광전소자들의 차세대 투명전도성 산화물(Transparent Conducting Oxide; TCO) 박막 재료로 주목 받고 있다. 특히 평판표시소자(FPD)들의 고해상도, 대면적화 및 경량화로 인해 투명전극용 박막의 고품위 특성이 요구되고 있다. 현재 투명 전극으로 널리 사용되고 있는 고가의 ITO(indium tin oxide)를 대체할 다성분계 산화물 투명 전극 중에서 투광성과 전기전도도가 좋은 IZO 박막에 대한 많은 연구가 진행되고 있다. 이러한 IZO 박막의 광학적, 전기적 특성은 박막 내의 조성 차이와 미세구조에 의해 결정된다. 따라서 고품위의 IZO 박막 형성을 위해서 결정구조와 미세구조에 대한 분석이 필수적이다. 본 연구에서는 Si(100) 기판 위에 DC-sputtering으로 증착한 IZO 박막의 열처리 온도에 따른 구조적 특성을 알아보기 위해 300~$600^{\circ}C$ 공기분위기에서 1시간 동안 열처리 하였다. 표면 형상(surface morphology)은 원자현미경(AFM). 결정구조는 X-선 회절(XRD)로 분석하였고, 미세구조는 투과전자현미경(TEM)으로 관찰하였다.