• 폴리머
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• 제27권4호
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• pp.313-322
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• 2003

상용화제와 교환반응 촉진제 도입에 따른 폴리(에틸렌 테레프탈레이트) (PET)/폴리(메타-자이렌 아디프아미드) (MXD-6) 블렌드의 형태구조 변화와 일축 연신한 블렌드 시료의 변형 형태구조를 조사하였다. 연신시료는 피브릴 구조의 분산상을 보여주었으며, 피브릴 구조는 연신비 증가에 따라서 점차 미세하게 변형되었다. 교환반응 촉진제나 상용화제의 첨가는 계면 접착력 향상에 기여하기보다는 분산상과 연속상 간에 결함을 야기함으로써 피브릴 구조의 균일성을 감소시켰다. H$_{v}$ 모드의 광산란을 이용하여 블렌드 조성과 연신비에 따른 고차구조 변화를 알아보았다. H$_{v}$ 산란패턴으로부터 결정들이 스택을 이루며, 스택은 연신 방향에 대하여 특정한 각도로 배향됨을 알 수 있었다. 분산상과 연속상 내의 결정은 연신비 증가에 따라서 점진적으로 배향되어, 연신비가 6.0인 경우에는 매우 높은 배향 수준을 보여주었다.

• 멤브레인
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• 제23권5호
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• pp.343-351
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• 2013

혼합 비료를 유도용액으로 하는 정삼투식 해수담수화에서 담수화 성능에 대한 유도용액 농도의 영향을 조사하였다. 혼합비료용액(DS)의 농도가 증가함에 따라 수투과선속은 거의 선형적으로 증가하였으나, PR (performance ratio)은 감소하였다. 또한 혼합비료용액의 농도가 600 g/L일 때, 해수 및 탈이온수를 각각 공급용액으로 하였을 경우 각각의 PR은 5.39 및 6.50이었다. 혼합비료용액의 농도가 증가함에 따라 N, P 및 K의 역용질선속은 거의 선형적으로 증가하였으나, 비역용질선속은 감소하였다. 역용질선속과 비역용질선속은 모두 질소(N) > 칼륨(K) > 인(P) 순으로 높게 나타났다.

• 한국염색가공학회지
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• 제15권6호
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• pp.33-38
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• 2003

This study surveys the effects of POY physical properties and processing conditions of belt texturing machine to the textured yarns. The various textured yarns are made with the variations of 1st heater temperature, draw ratio, velocity ratio, and the physical properties of these specimens such as yam linear density, tenacity, breaking strain, and wet and dry thermal shrinkages are measured and analysed with the various processing conditions of texturing machine. Especially, the thermal characteristics of the textured yarns, which are affected at the fabric hands and the determination of the processing conditions in the dyeing and finishing processes, are investigated through the thermal stress analyser and DSC experiments.

• 폴리머
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• 제27권4호
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• pp.323-329
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• 2003

기능성 도핑제인 di(2-ethylhexyl) sulffsuccinate sodium salt (NaDEHS)을 사용하여 화학적, 전기화학적 방법에 의한 연신성 폴리피롤을 합성하였다. 화학적, 전기화학적 방법에 의해 제조된 폴리피를 필름은 구역 연신 방법을 사용하여 1.0∼2.5배 연신시킬 수 있었으며, 연신된 폴리피를 필름의 전기 전도도를 측정하였다. 연신율이 증가함에 따라 필름의 전기 전도도는 증가함을 볼 수 있었다. 이러한 현상은 연신율에 따른 결정성 증가로 설명할 수 있었다. 온도변화에 따른 전하 이동 경로는 1.0-2.0배 연신된 폴리피롤의 경우 3차원 variable range hopping모델, 2.5배 연신된 폴리피롤의 경우 1차원 VHR모델에 적합함을 볼 수 있었다.

• 한국염색가공학회지
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• 제22권1호
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• pp.51-60
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• 2010

This research works on the effects of drawing conditions on the physical properties of the drawn worsted yarns. The drawn worsted yarns were made by the yarn drawing system under various drawing conditions such as concentration of reducing agent, draw ratio, setting time of drawn yarn, and concentration of oxidizing agent. The drawn worsted yarns from 2/80Nm to 2/90Nm were obtained from 2/60Nm worsted yarns, the surface and cross-sectional shapes and tensile properties of these various specimens were measured and discussed with the various drawing conditions. The drawing of worsted yarn made constituent wool fiber scratched and made it changing to polygonal cross-sectional shape. The tenacity and modulus were increased with draw ratio and concentration of reducing agent. And tensile strain was increased with draw ratio, which decreased with concentration of reducing agent.

• 한국물환경학회지
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• 제22권2호
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• pp.203-208
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• 2006

A continuous feed and cyclic draw SBR process was developed to overcome flow rate fluctuation and to maximize organic matters utilization efficiency for nitrogen and phosphorus removal. The developed SBR process was operated with two parallel reactors. Influent was supplied to one reactor which was not obligately aerated. At the same time, the other reactor was just aerated without supplying influent. In addition this mode was changed periodically. Cycle time was 6hr and aeration time ratio($t_{aer}/t_{total}$) was 0.33, respectively. $COD_{cr}$ and SS removal efficiencies of 95% or higher were achieved. Nitrogen removal was so greatly influenced by influent $COD_{cr}/T-N$ ratio. At influent $COD_{cr}/T-N$ ratio of 5.7, removal efficiencies of ammonia-N, T-N and T-P were 96%, 78% and 55%, respectively. Influent $COD_{cr}/T-N$ of 4 or higher ratio was necessary to achieve 60% or higher nitrogen removal. Organic matters of influent was efficiently utilized in denitrification reaction and consumed COD has a good correlation with removed T-N(about 6.5 mgCOD/mgTN). Continuous feed and cyclic draw SBR process could be one of alternative processes for the removal of nutrients in rural area where $COD_{cr}/T-N$ ratio was low and fluctuation of flow rate was severe.

• 폴리머
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• 제24권6호
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• pp.820-828
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• 2000

본 연구에서는 블렌드 내의 분산상을 잘 발달된 판상 구조로 발현시켜 폴리프로필렌 (PP)/에틸렌 비닐알코올 공중합체 (EVOH) 블렌드의 차단 성질을 향상시키기 위하여 필름 제조 공정으로써 이축연신 공정을 사용하였다. 분산상 수지와 연속상 수지의 점도비로부터 용융 압출 공정시 변형의 정도를 파악하기 위하여 각 수지의 유변물성을 측정하였으며, 상용화제 함량과 연신 배율 및 연신 온도 등이 이축연신 블렌드 필름의 산소 투과도와 모폴로지에 미치는 영향을 조사하였다. l5 wt%의 EVOH를 첨가한 PP/EVOH 블렌드 필름의 산소차단성은 EVOH 분산상이 이축연신에 의해 넓은 면적의 판상구조로 발현되어 순수 PP에 비해 10배 정도까지 증가한 것으로 나타났다. 모폴로지를 조절하친 두 상간의 계면결합력을 증진시키기 위하여 PP-g-MAH와 ionomer를 사용한 결과, 차단 효과를 효과적으로 향상시키기 위해서는 상용화제를 블렌드에 최적의 함량으로 첨가해야 한다는 사실을 알 수 있었다. 또한 높은 연신 배율과 연신 온도로 이축연신하여 제조된 블렌드 필름에서 더욱 뚜렷한 판상 모폴로지가 관찰되었으며, 차단효과는 증가한 것으로 나타났다.

• 전기화학회지
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• 제9권1호
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• pp.29-33
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• 2006

A new porous separator based on poly(vinyl chloride) (PVC)/poly(vinylidene fluoride-co-hexafluoro-propylene) (P(VdF-co-HFP)/poly(methyl methacrylate) (PMMA) was prepared by a phase inversion method. To enhance mechanical property, the membrane was stretched uniaxially at high temperature. Tensile strength and ionic conductivity were measured for various draw ratios. The tensile strength and ionic conductivity were increased with increasing draw ratio. The tensile strength of the separator reached 52MPa after stretching to draw ratio of 5, and the ionic conductivity of the separator was increased from $1.9Xs10^{-4}S/cm\;to\;4.6X10^{-4}S/cm\;at\;25^{\circ}C$. The stretched separator immersed in liquid electrolyte was electrochemically stable up to 4.7 V. The cell based on the stretched separator was maintained at about 99% of the initial discharge capacity after 10th cycle operation at 0.2C rate.

• 한국염색가공학회지
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• 제28권3호
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• pp.125-133
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• 2016

In this study, efforts were made to enhance the mechanical properties of the poly(vinyl alcohol) (PVA) fibers of medium molecular weight(number-average degree of polymerization=1735) varying the ratio in $DMSO/H_2O$ mixed solvent and spinning/drawing conditions. The gel fibers prepared from pure DMSO were opaquely frozen in the coagulating bath of $-20^{\circ}C$. However, transparent gel fibers were formed without freezing for the mixture to contain water less than 80wt%. As the amount of water in the mixture increased the residual solvent in the coagulated gel fibers decreased ranging from 85 to 42wt%. The complex viscosity increased with increasing PVA concentration in 80/20 $DMSO/H_2O$ exhibiting remarkable shear thinning at 18wt%. In the Cole-Cole plot, the 18wt% PVA solutions gave a deviated curve from 12 and 15wt% ones. Thus the optimum PVA concentration for the spinning processing of medium MW PVA solutions in 80/20 $DMSO/H_2O$ was determined to 18wt% with rheological concept. Low degree of drawing during hot drawing process in the dry state was available for high bath draft in the coagulation bath. The most improved mechanical properties were observed by applying the highest possible draw ratio attained by reducing bath draft over multi-step drawing process. In the given bath draft, linear relationship was observed between both tensile strength and modulus and draw ratio showing the inflection points at the draw ratio of 19.5 and 18.0 for tensile strength and modulus, respectively.

• PNF and Movement
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• 제13권1호
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• pp.25-30
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• 2015

Purpose: The aim of this study was to examine the effects of abdominal muscle contraction thickness using real-time ultrasound imaging while applying an abdominal draw-in maneuver (ADIM) and pelvic floor muscle contraction (PFC) to low back pain patients and healthy subjects. Methods: The subjects were 21 young adults; a group of 10 low back pain patients and a control group of 11 healthy subjects. Measurements were made with the subjects on a pillow in a supine position, with the knee joints flexed at 60 degrees. While the two groups conducted ADIM and PFC, their transverse abdominal muscle (TrA), internal abdominal oblique muscle (IO), and external abdominal oblique muscle (EO) thicknesses were measured using an ultrasound imaging system. Result: The TrA muscle contraction thickness ratio during PFC and ADIM was significantly lower in the low back pain group than in the healthy group (p<0.05). The EO muscle contraction thickness ratio during ADIM was also significantly lower in the low back pain group than in the healthy group. The healthy group's muscle contraction thickness ratio was significantly lower during PFC than during ADIM in the TrA, IO, and EO (p<0.05). The low back pain group's muscle contraction thickness ratio was lower during PFC than during ADIM in the TrA, IO, and EO, but the difference was not statistically significant. Conclusion: The results of this study indicate that oral direction during ADIM induced an appropriate contraction of the TrA. Therefore, the procedure reported here may be applied during rehabilitation for appropriate contraction of the TrA.