• 한국토양비료학회지
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• 제39권4호
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• pp.224-229
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• 2006

다량으로 배출되고 있는 축산분뇨를 퇴비화 하여 농지로 투입하는 것은 토양의 물리화학성 개선 등의 유효한 효과가 있지만, 적절한 부숙화 과정을 거치지 않은 미부숙 물질을 투여하면 나쁜 영향을 끼치게 된다. 축산분뇨를 이용한 부산물 비료의 제조에 있어서 적절한 부숙도 관리가 중요한 이유이다. 따라서 축산부산물을 주원료로 하고 부재료와 부숙 기간을 7가지 단계로 달리한 부산물비료를 대상으로 부숙화에 따른 화학성의 변화 경향 파악과 색도, 점도, 입도, 용적밀도 등의 물리성 변화를 아울러 조사하여, 부숙도에 대한 판정지표를 추출하고자 하였다. 휴민산 함량, 유기물/질소 비율, 양이온치환용량, 염함량 등의 화학성이 부숙정도와 밀접한 관련이 있었으며, 물리적 특성에서는 수분함량, 입자밀도 및 용적밀도, 입경별 분포, 색도 등이 부숙도의 판정지표로 사용할 수 있음을 알 수 있었다.

• 한국토양비료학회지
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• 제49권6호
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• pp.807-812
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• 2016

Soil amendment, especially addition of clay minerals, has been widely conducted to improve the physical and chemical properties of cultivated soils. However, there are no systematic studies on the effects of the structural type of clay minerals added. This study was conducted to investigate the effects of structural type of clay minerals on physical properties of soils. Two experimental soils, layer-dominant and granule-dominant ones, were mixed with either a layer-type smectite or a granule-type zeolite at a level of 2.0 wt%. It was observed that water permeability of soils was decreased by smectite whereas not significantly changed by zeolite. This effect was much greater in layered clay-dominant soil than in granular clay-dominant soil. Our results clearly indicated that the relationship of structural type between a soil and an amendment plays a decisive role in the soil properties. Therefore, it is highly recommended that the structural types of both soil and amendment be taken into consideration for soil amendment by clay minerals.

• Journal of Microbiology and Biotechnology
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• 제26권10호
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• pp.1746-1754
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• 2016

Recently, spherical beads entrapping quorum quenching (QQ) bacteria have been reported as effective moving QQ-media for biofouling control in MBRs for wastewater treatment owing to their combined effects of biological (i.e., quorum quenching) and physical washing. Taking into account both the mass transfer of signal molecules through the QQ-medium and collision efficiencies of the QQ-medium against the filtration membranes in a bioreactor, a cylindrical medium (QQ-cylinder) was developed as a new shape of moving QQ-medium. The QQ-cylinders were compared with previous QQ-beads in terms of the QQ activity and the physical washing effect under identical loading volumes of each medium in batch tests. It was found that the QQ activity of a QQ-medium was highly dependent on its specific surface area, regardless of the shape of the medium. In contrast, the physical washing effect of a QQ-medium was greatly affected by its geometric structure. The enhanced anti-biofouling property of the QQ-cylinders relative to QQ-beads was confirmed in a continuous laboratory-scale MBR with a flat-sheet membrane module.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제21권1호
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• pp.39-61
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• 2017

In this present article, we analyzed the heat and mass transfer characteristics of the nonlinear unsteady radiative MHD flow of a viscous, incompressible and electrically conducting fluid past an infinite vertical porous plate under the influence of Soret and chemical reaction effects. The effect of physical parameters are accounted for two distinct types of thermal boundary conditions namely prescribed uniform wall temperature thermal boundary condition and prescribed heat flux thermal boundary condition. Based on the flow nature, the dimensionless flow governing equations are resolved to harmonic and non harmonic parts. In particular skin friction coefficient, Nusselt number and Sherwood number are found to evolve into their steady state case in the large time limit. Parametric study of the solutions are conducted and discussed.

• Korea-Australia Rheology Journal
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• 제20권4호
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• pp.213-220
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• 2008

The effects of temperature on the rheological properties of the solutions of poly(vinylidene fluoride-co-hexafluopropylene) (PVDF-HFP) in dimethyl acetamide (DMAc) were investigated in terms of frequency and concentration. The effects of temperature on the intrinsic viscosity of the solutions were discussed. In dynamic rheological measurement, the concentrated solutions showed a little unexpected rheological response; as temperature was increased dynamic viscosity was increased and the solutions exhibited more noticeable Bingham body character over the temperature range, 30 to $70^{\circ}C$. In addition, the solution gave longer relaxation time, lower value of loss tangent and higher value of yield stress at higher temperature and at higher concentration. On the other hand, the dilute solutions revealed that intrinsic viscosity was decreased and its Huggins constant was increased with increasing temperature. These physical parameters suggested that the increase of viscosity with increasing temperature resulted from the localized gelation of PVDF-HFP due to reduced solubility to the solvent.

• 한국진공학회지
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• 제9권4호
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• pp.394-399
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• 2000

Underlayer의 종류 및 두께가 Al 박막의 texture 및 면저항 변화에 미치는 영향을 연구하였다. Al의 underlayer로는 ionized physical vapor deposition(I-PVD)에 의해 제조된 Ti와 I-PVD Ti 위에 metalorganic chemical vapor deposition(MOCVD)에 의해 제조된 TiN을 적층한 구조가 사용되었으며, 각각에 대해 두께를 변화시키면서 Al 박막의 배향성, 면저항을 조사하고, $400^{\circ}C$, $N_2$분리기에서 열처리하면서 면저항의 변화를 조사하였다. I-PVD Ti만을 Al의 underlayer로 사용한 경우, Ti두께가 5 nm이어도 Al 박막이 우수한 <111> 배향성을 나타내었으나, Al-Ti반응 때문에 열처리 후 Al 배선의 면저항이 크게 상승하였다. I-PVD 와 Al 사이에 MOCVD TiN을 적용함에 의해 Al <111> 배향성의 큰 저하없이 Al-Ti 반응에 의한 면저항의 증가를 억제할 수 있었으며, MOCVD TiN의 두께가 4 nm 이하일 때 특히 우수한 Al <111> 배향성을 나타내었다.

• Elastomers and Composites
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• 제25권1호
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• pp.13-19
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• 1990

The purpose of this study is to estabilish the synthetic condition of polyurhethane elastomer for excellent properties. Polyurethane elastomer which have different NCO percentage and hard segment contents was synthesized by casting method. And the effects of hard segment contents were investigated by analytical methods such as IR, DSC, etc. [NCO]/[OH] ratio was proper at the range $1.02{\sim}1.05$. By IR absorption peak($1250cm^{-1}$) which indicate interurethane hydrogen bond it was confirmed that hard segment were crystallized. Melting point that was determined by DSC showed the effects of hard segment contents, phase mixing and crystalline size.

• 한국연초학회지
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• 제13권2호
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• pp.66-70
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• 1991

A field experiment was conducted to study the effects of fertilizer application rate and number of harvested leaves per plant on selected agronomic, chemical and physical characteristics of burley tobacco(Nicotiana tabacum L. cv Burley 21) in 1988, 1989 and 1990 at Chonju Experiment Station, Korea Ginseng SE Tobacco Research Institute. 175.0 or 227.5 kilogram per 10a of compound fertilizer(N-P2O5-K2O= 10-10-20) were applied as main plot, and 2 or 4 of upper leaves was topped off with 0, 2 or 4 of the lower leaves removed as sub plot. Yield, total alkaloid and total nitrogen content of cured leaves were high in the higher level of compound fertilizer plot, and increasing the level of compound fertilizer had an adverse effect on physical characteristics. Reducing the number of harvested leaves had a negative effect on yield regardless of whether the leaf number was reduced by lower topping or removing the bottom leaves, but increased the rate of higher grades leaves. Differences in total alkaloid, total nitrogen and some physical properties among number of harvested leaf per plant were smaller than expected.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.335-338
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• 2010

In this study, the atmospheric plasma treatment with $He/O_2$ was conducted to modify the surface chemistry of carbon fibers. The effects of plasma treatment parameters on the surface energetics of carbon fibers were experimentally investigated with respect to gas flow ratio, power intensity, and treatment time. Surface characteristics of the carbon fibers were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Fourier transform infrared (FT-IR), Zeta-potential, and contact angle measurements. The results indicated that oxygen plasma treatment led to a large amount of reactive functional groups onto the fiber surface, and these groups can form together as physical intermolecular bonding to improve the surface wettability with a hydrophilic polymer matrix.

• 한국산림과학회지
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• 제104권1호
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• pp.84-89
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• 2015

'대보' 박피밤의 갈변 및 품질에 화학물질(ascorbic acid, citric acid, calcium chloride: 1% 용액)과 물리적(진공포장, $50^{\circ}C$ 증류수) 처리가 미치는 영향을 조사하였다. 박피밤 색도의 L값은 모든 처리구에서 저장기간이 경과함에 따라 감소하는 경향을 나타낸 반면, ${\Delta}E$값은 점차 증가하는 경향을 보였다. 일반포장 처리구가 급격히 색 변화가 일어나는데 비해 화학 및 물리적 처리구는 완만한 변화를 보였다. 특히 calcium chloride 처리구는 색 변화가 거의 일어나지 않았다. 관능적 품질평가 결과, 상품성은 일반포장 처리구가 10일간 유지되었던 반면 화학 및 물리적 처리구들은 35일간 상품성이 유지되었다. 따라서 '대보' 박피밤의 화학 및 물리적 처리는 갈변을 억제시킴으로써 박피밤의 관능적 품질유지에 효과적이였고, 특히 1% calcium chloride 침지 후 진공포장하는 것이 박피밤의 품질유지와 갈변 억제에 가장 효과적인 것으로 판단되었다.