• 대한환경공학회지
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• 제27권8호
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• pp.886-891
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• 2005

본 연구는 침지형태로 운전되는 중공사막 결합형 생물반응기(HFMB) 시스템의 VOC 처리능력 및 안정성을 평가하기 위하여 수행되었다. 일차적으로 미생물이 없는 조건에서 VOC 물질전달을 알아보기 위한 abiotic test를 통해, 본 연구에서 사용한 HFMB는 미세기포를 이용한 산기관과 유사한 물질전달율을 나타냄을 확인하였다. 그러나 HFMB는 일반 산기관 시스템과는 달리 기체 유속과 중공사막 개수를 증가시켜 물질전달율을 더욱 증대시킬 수 있을 것으로 예측된다. 또한 반응조에 톨루엔 분해 미생물을 첨가하고 다양한 유입부하 조건에서의 기체상 톨루엔 제거 실험을 수행하였는데, 50, 100, $500\;g/m^3/hr$의 유입부하 조건에서 $70{\sim}80%$ 수준의 처리효율을 얻을 수 있었다. 추가적으로 수행된 분해능 실험에서는 최대 $800\;g/m^3/hr$ 이상의 분해능을 실험적으로 확인하여, 문헌에 제시된 기존 생물여과공법의 최대분해능($50{\sim}100\;g/m^3/hr$) 보다 월등히 높았다. 따라서 HFMB는 기존의 VOC 저감기술을 대치할 수 있는 친환경적인 기술이라고 판단된다.

• 한국입자에어로졸학회지
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• 제9권4호
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• pp.231-238
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• 2013

Carbon nanotubes (CNTs) are one of the nanomaterials that were discovered by Iijima in 1991 for the first time. CNTs have long cylindrical and axi-symmetric structures. CNTs are made by rolling graphene sheets. Because of their large length-to-diameter ratio, they are called nanotubes. CNTs are categorized as single-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs) based on the shell structures. CNTs are broadly used in various fields, such as scanning probe microscopy, ultra fine nano balance and medicine, due to their extraordinary thermal conductivity, electrical and mechanical properties. Because long, straight CNTs have the same shape as asbestos, which cause cancer in cells lining the lung, there have been many studies on the effects of MWCNTs on human health that have been conducted. Stable atomization of CNTs is very important for the estimation of inhalation toxicity. In the present study, electro-static assisted axial atomizer (EAAA), which is the instrument that uses MWCNTs and aerosolizes them by transforming the single fiber shape using ultrasonic dispersion and electric field, was invented. EAAA consists of a ultrasonic bath for dispersion of MWCNTs and a particle generator for atomizing single fibers. The performance evaluation was conducted in order to assess the possibilities of 6-hour straight atomization with stability, which is the suggested exposure time in a day for the estimation of inhalation toxicity.

• 대한기계학회논문집A
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• 제41권1호
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• pp.41-48
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• 2017

최근 에너지, 바이오공학, 전자공학 등 다양한 분야에서 초미세 고분자섬유의 활용이 증대되고 있다. 이러한 고분자 섬유의 제작방법의 하나로서 전기방사법은 타 공정에 비해 공정장치가 간단하고 재료의 선택에 제한이 적은 등 다양한 장점을 가져 활발하게 사용되고 있다. 그러나 전기방사공정은 미세한 고분자 섬유가 전기장이 부가된 공기층을 통과하면서 높은 불안정성을 가지기 때문에 전기방사공정을 통해 제작되는 섬유매트의 형상 및 기하학적 특성의 조절이 어려운 단점을 가지고 있다. 본 연구에서는 서로 다른 두 가지 용매를 이용하여 섬유의 직경을 나노섬유와 마이크로섬유로 제작할 수 있음을 보였으며, 이를 조합하여 기계적 특성과 공극률을 조절할 수 있는 하이브리드 섬유매트를 제작할 수 있음을 보였다. 또한 제작된 매트를 이용하여 기계적 특성과 공극률이 조절될 수 있음을 확인하였다.

• 한국의류산업학회지
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• 제15권6호
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• pp.985-992
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• 2013

Polytrimethylene terephthalate(PTT) offers several advantageous properties such as good tensile strength, uniformity, stiffness, toughness, UV stability, resilience, stain resistance, outstanding elastic recovery, and dyeability. The effects of annealing temperature on physical properties and the structure of PTT filaments and yarn were investigated by measuring wide-angle X-ray diffraction (WAXD), density, optical birefringence, dynamic visco elasticity, and tensile testing. The intensity of maximum tan ${\delta}$ decreased and the temperature of maximum tan ${\delta}$ shifted to a higher temperature as the annealing temperature of filaments increased; however, it shifted to a lower temperature when the annealing temperature exceeded $130^{\circ}C$. In addition, crystallinity, density and D-spacing of (010) crystal face increased as the annealing temperature increased. Optical birefringence and specific stress were almost constant up to $100^{\circ}C$ and then decreased above $130^{\circ}C$. The shrinkage of PTT filament is 0 in boiling water when annealed above $130^{\circ}C$; consequently, the use of annealed fiber above $130^{\circ}C$ can remove thermal instability when dyeing PTT fiber. In the case of yarns, the thermal stability and physical properties of yarns showed the best effect when the ply number is less than 5, twist number is less than 400tpm, and the annealing time is 20minutes.

• 멤브레인
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• 제9권3호
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• pp.185-192
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• 1999

반도체 산업의 wafer 가공공정에서 발생하는 폐수를 재활용하고자 한외여과 공정을 이용한 막분리 공정의 도입 가능성을 검토하였다. Pilot 규모의 장치에 분획분자량이 각각 10,000, 20.000, 30,000인 한외여과막 모듈을 이용하여 투과유속 및 제거율 등을 측정하였다. 투과수의 성상은 SDI15, 탁도, 전기전도도, 실리콘 농도분석을 통해 공정수로 재이용이 가능함을 확인할 수 있었다. 투과유속 저하를 막기 위한 역세척 방법으로는 압축공기와 물은 sweeping 하는 방법이 가장 효과적이었고, 이때 투과유속의 회복율이 높게 나타났다. 분획분자량 30,000인 한외여과막에서 가장 높은 투과유속을 나타내었다. 또한 폐수의 평균 실리콘 입자 평균 함량은 3.8-5.6mg/$\ell$이고, 투과수의 실리콘 입자 함량은 0.2${\mu}g$/$\ell$이하로 나타나 제거율은약 96%이상으로 나타났다.

• 펄프종이기술
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• 제34권2호
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• pp.1-12
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• 2002

Starch dissolved in paper-mill wastes, either as a result of poor retention on the paper web or recycling of surface-treated broke, was a major pollutant Laboratory tests were performed by using different kinds of starch as a surface treatment. It was concluded that the use of cationic starch can positively affect the level of starch dissolved in liquid effluents. When cationically modified starches were used for surface sizing, the starch was tightly bound to the paper fibers, it was not removed during the repulping of broke. The result of mill trial in fine paper manufacture for the application of low-viscosity cationic starches used in size press reduced COD load in the effluents and increased One Pass Retention. It had been found that when cationic starch used as a surface sizing agent, more starch was retained on or near the surface of the sheet than with conventional oxidized starches. Thus surface strengths and quality were improved. In addition it is possible to maintain the desired level of starch penetration into the fiber net and improve porosity, opacity and brightness. In contrast, in most cases, dusting problems are notably eliminated. Cationic surface sized starch improved black and color ink-jet print quality in terms of feathering and optical density of the print image. These improved properties were believed to be due to a combination of fiber bonding and surface orientation more uniform starch concentration on the paper surface was resulted. Moreover cationic charges in the paper surface lend themselves excellently to fix ink jet ink anionic in nature.

• 한국의류산업학회지
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• 제16권3호
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• pp.476-484
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• 2014

The purpose of this study was to investigate the dyeing properties and anti-microbial ability of silk and wool fabrics dyed with Terminalia chebula Retzius(TCR) extract using two extraction solvent, hot water and methanol. Dyeing properties of fabrics were studied by investigating the characteristics of colorant, changes in dye uptake under different dyeing conditions, and by investigating color change when mordants were applied. Also, color fastness, and antimicrobial activity of dyed fabrics were estimated. Regardless of extraction solvent type, colorant showed maximum absorption wavelength at 280 nm and 578 nm, which implied that tannin was the major pigment component of TCR. Also, through FT-IR spectrum result, it was confirmed that tannin of TCR methanol extract was hydrolysable tannin. But for the hot water extract, it was only assumed that its tannin was condenced tannin. Fabric dyed with hot water solvent extract showed higher dye uptake than fabric dyed with methanol solvent extract, dye uptake increasing by higher concentration of the dye, longer dyeing time and higher dyeing temperature. And the absorption curve between TCR extract and protein fiber was shaped in the form of Langmuir adsorption isotherm. Fabric dyed without mordant was yellow in color, and when dyed with mordant, fabric showed various colors depending on mordant types except Sn. Color fastness to washing was generally fine and color fastness to light was moderate. But color fastness to rubbing and dry cleaning was outstanding. Lastly, dyed fabrics showed very good antimicrobial activity of 99.9% against Staphylococcus aureus and Kiebsiella pneumoniae.

• Applied Microscopy
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• 제44권1호
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• pp.21-29
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• 2014

Retinal glial responses to hypertensive glaucomatous injury were spatiotemporally surveyed. Retinas as a whole or vertical sections were processed for anti-glial fibrillary acidic protein (GFAP), anti-Iba1, anti-nerve growth factor (NGF), and anti-tumor necrosis factor (TNF)-${\alpha}$ immunohistochemistry for confocal microscopic analyses. The optic nerve head of paired controls was processed for electron microscopy. GFAP positive astrocytes appeared in the nerve fiber layer in the glaucomatous and control retinas, changing from fine protoplasmic to stout fibrous parallel to glaucomatous duration. Iba1 positive microglia appeared in both retinas, and enormous reaction appeared at the latest glaucomatous. M$\ddot{u}$ller reaction detected by GFAP reactivity expanded from the end feet to whole profile following to duration in the glaucomatous. NGF reactivity expended from the end feet to the proximal radial processes of the M$\ddot{u}$ller cells in both retinas according to glaucomatous duration. TNF-${\alpha}$ immunoreactivity in the nerve fiber layer was stronger in both the glaucomatous and controls than in the normal, and exceptionally at the latest glaucomatous was even lower than the normal. The astrocytes in the optic nerve head are interconnected with each other via gap junction. These results demonstrate that astrocyte reaction propagates to the contralateral via physical links, and TNF-${\alpha}$ is correlated with NGF production for neuroprotection in response to hypertensive glaucomatous injury.

• 설비공학논문집
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• 제20권12호
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• pp.820-824
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• 2008

Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, the electret filter is made by electrospinning process using Polystyrene which is dissolved by 5 : 5 of Tetrahydrofuran (THF) and Dimethylformamide (DMF). Also the electrical properties and the filtration performances of electrospun filter media are Quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. The surface charge potential and the surface charge density of electrospun PS filters are increased with increasing applied voltage and saturated at 30 kV of applied voltage. Also collection efficiency of electro spun filters is increased with increasing surface charge potential and surface charge density. But the surface charge potential is decreased by natural decay and it causes deterioration of particle collection efficiency.

• 한국식품영양과학회지
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• 제22권6호
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• pp.763-770
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• 1993

To investigate the quality changes during frozen storage, top shell, Omphalius pfeifferi capenteri, was stored at -18$^{\circ}C$, -$25^{\circ}C$ and -3$0^{\circ}C$ immediately after shelling and water holding capacity, protein composition and histological features were examined with the lapsed period of the storage. During the storage period, amount of free drip was increased with higher frozen temperature and longer frozen period, but with the longer storage period, the lower water holding capacity was observed. The extractability and composition of muscle protein, sarcoplasmic protein and stroma protein were rather stable regardless of frozen temperature and frozen storage period. However, the extractability of myofibrillar protein was decreased with higher frozen temperature and longer frozen storage period. On the changes of muscle tissue structure, following points were observed. 1) In the muscle tissue structure of fresh sample, fine muscle fiber was closely distributed all over the tissue regardless of cross and longitudinal section. 2) In tissue structure under frozen state, it was observed that ice crystals apparently grew with the higher storage temperature. Empty spaces between muscle bundles which wee formed by aggregations of muscle fiber were observed after 3 months storage at -18$^{\circ}C$ . 3) Tissue structure in thawed state was restored satisfactorily after 1 month storage regardless of storage temperature. After 3 months storage at -3$0^{\circ}C$, muscle tissue was well restored, but at -18$^{\circ}C$, empty spaces were apparent due to incomplete restoration.