• 청정기술
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• 제20권2호
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• pp.154-159
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• 2014

본 연구에서는 노말 메틸 피로리돈(N-methyl-2-pyrrolidone, NMP)을 대신하여 다이메틸설폭시화물(dimethyl sulfoxide, DMSO)을 용매로 사용하여 폴리염화비닐 (poly vinyl chloride, PVC)로 리튬망간산화물(lithium manganese oxide, LMO)를 고정화하여 PVC-LMO 비드를 제조하였다. XRD 분석을 통해 PVC-LMO 비드내에 LMO가 잘 고정화 된 것을 확인 하였다. 합성한 PVC-LMO 비드의 크기는 약 4 mm였다. PVC-LMO 비드에 의한 리튬이온 흡착 실험은 회분식으로 수행하였다. 랭뮤어 모델식으로 부터 구한 최대 흡착량은 21.31 mg/g였다. PVC-LMO 비드에 의한 리튬이온 흡착특성은 유사 2차 속도모델식으로 잘 설명되었으며, 내부확산 단계가 흡착속도 결정단계인 것으로 사료되었다.

• 멤브레인
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• 제2권1호
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• pp.67-73
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• 1992

건습식방법에 의해 제조된 중공사는 1차적으로는 방사원액 및 내외부응고제의 조성과 양 그리고 방사높이 드의 방사조건에 의해 막의 전체적인 구조 및 투과성능이 영향을 받지만 제조된 중공사의 건조과정이나 용매처리, 열처리등에 의해서도 큰 영향을 받는다. 본 실험실에서는 건습식방사법에 의해 한외여과용 폴리설폰중공사막을 제조하여 후처리조건을 변화시켜가면서 그 중공사막의 투과특성을 조사하였다. 그 결과 건습식방사법에 의해 제조된 폴리설폰중공사는 건조시간이나 건조온도가 증가하면 막의 수축이 크게 일어나서 툭수헝이 크게 감소하고 역으로 용질배제율은 높아지며 한범 감소된 막의 투수성은 회복이 불가능하다. 따라서 중공사의 투과성능을 보존하기위해서는 100%글리세린으로 처리하여 막의 건조를 피해야한다는 사실과 $20^{\circ}$C의 흐르는 water에서 수세하는 경우 단시간에 중공사의 잔여용매(NMP, DMAc)를 제거하기는 어려우며 이러한 잔여용매는 중공사막의 투과성능의 안정성 및 재연성을 크게 손상시키기 때문에 열수처리를 해주어야 한다는 것을 알았다. $100^{\circ}$C 열수처리결과 단시간에 잔여용매의 제거가 가능하였으며 투과성능도 안정적으로 얻을 수 있었다.

• Advances in materials Research
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• 제2권4호
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• pp.209-219
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• 2013

We have described primary studies on conductivity and molecular weight of polyaniline separately in the electric and magnetic fields when it is used in a field effect experimental configuration. We report further studies on doped in-situ deposited polyaniline. First we have chemically synthesized polyaniline by ammonium peroxodisulfate in acidic aques and organic solutions at different times. Then we measured mass and conductivity and obtained the best time of polymerizations. In continue, we repeated these reactions separately under different electric and magnetic fields in constant time and measured mass and conductivity. The polyaniline is characterized by gel permeation chromatography (GPC), UV-Visible spectroscopy and electrical conductivity. High molecular weight polyanilines are synthesized under electric field, $M_w$ = 520000-680000 g/mol, with $M_w/M_n$ = 2-2.5. The UV-Visible spectra of polyanilines oxidized by ammonium peroxodisulfate and protonated with dodecylbenzenesulfonic acid (PANi-DBSA), in N-methylpyrolidone (NMP), show a smeared polaron peak shifted into the visible. Electrical conductivity of polyanilines has been studied by four-probe method. The conductivity of the films of emeraldine protonated by DBSA cast from NMP are higher than 500 and 25 S/cm under 10 KV/m of potential) electric field and 0.1 T magnetic field, respectively. It shows an enhanced resistance to ageing too. By the next steps, we carried chemical polymerization at the best electric and magnetic fields at different times. Finally, resulted in finding the best time and amount of the fields. The longer polymerization time and the higher magnetic field can lead to degradation of polyaniline films and decrease conductivity and molecular mass.

• 접착 및 계면
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• 제20권2호
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• pp.53-60
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• 2019

여러 종류의 용매와 상용화되어 있는 비공유결합성 분산제들을 이용하여 안정한 그래핀 분산액을 제조 하였다. 분산액은 3시간의 초음파 처리를 통하여 제조 되었으며, NMP 용매에서는 Tween 계열과 Span 계열과 Pluronic 계열의 분산제가 안정한 그래핀 분산액을 형성하였다. 또한 에탄올 용매에서는 질소를 포함한 분산제 종류가 안정한 분산액을 형성하였으며, 물과 dichloromethane에서는 모든 분산제에 대하여 대체로 불안정하였지만 poly(4-vinyl pyridine)과 sodium dodecyl sulfonate를 사용한 경우 일부 안정한 분산액을 형성 하였다. 또한 Poly(4-vinyl pyridine), poly(vinyl pyrrolidone), poly(2-(dimethylamino)ethyl methacrylate)를 이용하여 더 큰 용량의 그래핀 분산액을 제조하였다. 본 연구는 그래핀의 분산을 위한 여러 용매 및 분산제에 대한 기준을 제공할 수 있을 것으로 기대된다.

• Composites Research
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• 제35권1호
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• pp.47-51
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• 2022

전자기기 발열을 효율적으로 제어하기 위해 열전도성 복합재료에 대한 많은 연구가 진행되고 있다. 본 연구에서는 solvent 별 분산에 따른 carbon fiber의 배열성 관계를 알아보기 위해 Milled Carbon Fiber를 4가지 Solvent에 분산하고 Vacuum filtration 방법을 통해 탄소섬유강화 복합재료(CFRP)를 제작하였다. CFRP의 배열성을 알아보기 위해 광학현미경 관측과 섬광법을 통한 열전도도를 측정하였다. NMP와 Ethanol을 Solvent로 사용하여 성형한 CFRP의 평면두께방향 열전도도가 각각 10.79 W/mK, 10.57 W/mK 값을 보였고 이는 평면내부방향 열전도도에 비해 218%, 209% 향상된 결과를 보였다. Solvent의 상대적으로 높은 점도 값은 solvent 유체의 높은 전단력에 영향을 주어 성형 시 필러의 배열성을 결정하는데 영향을 주는 것으로 판단된다.

• Journal of Astronomy and Space Sciences
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• 제40권3호
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• pp.113-122
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• 2023

Although the Relative Global Navigation Satellite System (GNSS) positioning technique provides high accuracy, it has several drawbacks. The scarcity of control points, the long baselines, and using of ultra-rabid and rabid products increased position errors. This study has designed a New MATLAB Program that helps users automatically select suitable IGS stations related to the baseline lengths and the azimuth between GNSS points and IGS stations. This study presented criteria for the length of the baselines used in Egypt and an advanced estimated accuracy before starting the project. The experimental test studies the performance of the position accuracy related to the relation between three factors: observation session, final, rabid, and ultrarabid products, and the baseline lengths. Ground control point mediates Egypt was selected as a test point. Nine surrounding IGS stations were selected as reference stations, and the coordinates of the tested point were calculated based on them. Baselines between the tested point and the IGS stations were classified regarding proposal criteria. The coordinates of the tested point were obtained in different observation sessions (0.5, 1, 2, 4, 5, 6, 7, 7.5 h). The results indicated that the lengths of the baseline in Egypt were classified short (less than 600 km), medium (600-1,200 km), and long (greater than 1,200 km) and required a minimum observation time of 4, 5, and 7 h to obtain accuracy 10, 19, 48 mm sequentially. The position accuracy was superior for the rapid and the final than the ultra-rapid products by 16%. A short baseline was at the best case; there was a performance in position accuracy with a 57% deduction in observation time compared with the long baseline.

• Korean Membrane Journal
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• 제9권1호
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• pp.1-11
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• 2007

To prepare chemically stable asymmetric microporous membranes with a hydrophilic surface, which would be expected to have better antifouling properties, poly(vinylidene fluoride) (PVDF) blend membranes were prepared by the phase inversion process. PVDF mixture solutions in N-methylpyrrolidone (NMP) blended with several polar potential ionic polymers such as polyacrylonitrile (PAN), poly(methylmethacrylate) (PMMA) and poly(N-isopropylacrylamide) (NIPAM) were used for the formation of the PVDF blend membranes. They were then characterized with several analytical methods such as FESEM, FTIR, contact angle measurement, pore size distribution and permeability measurement. Regardless of different polar polymers blended, they all showed a finger-like structure with more hydrophilic surface than the pristine PVDF membrane. For all the PVDF blend membrane, due to the polar potential ionic polymers used, the flux of those was improved. Especially the PVDF blend membrane with NIPAM showed the highest flux among the membranes prepared. Also antifouling property of the PVDF membrane was improved by the use of the polar polymers.

• 접착 및 계면
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• 제7권1호
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• pp.23-29
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• 2006

Polymer thin films of pentafluorostyrene (PFS) were prepared by RF plasma (13.56 MHz) polymerization in continuous wave (CW) mode, as a function of plasma power and monomer pressure. Conditions for film preparation were optimized by measuring the solvent resistance of plasma polymer thin films in DMAc, NMP, THF, acetone and chloroform, as well as by evaluating the optical clarity via UV-VIS measurements. Pulsed mode plasma polymerization was also utilized to enhance the optical properties of the films by varying the period of on-time and duty cycle. Finally, the films were subjected to refractive index measurements and analyzed by ${\alpha}$-step, TGA and FT-IR.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.85.2-85.2
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• 2010

There is widespread effort to develop polymer membranes in place of Nafion for high temperature polymer electrolyte membrane fuel cell(PEMFC). In our study, SiO2 membranes are arranged by electrospinning method. For impregnation solution, the modified sulfonated poly(ether ether ketone)(SPEEK) polymer is prepared from sulfonation, sulfochlorination, partial reduction and lithiation reaction. The modified polymer is cross-linked with 1,4-diiodobetane in NMP solvent and then blended with Heteropoly acid(HPA). The characterization of membranes is confimed by FT-IR, Thermogravimetry(TGA), water uptake test and single cell performance test for PEMFC, etc. The composite membrane shows satisfactory thermal and mechanical properties. Beside, The membrane exhibits good ion exchange capacity and high proton conductivity. As a result, The composite membrane is promising as an alternative membrane in high temperature PEMFC.

• Carbon letters
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• 제10권1호
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• pp.19-22
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• 2009

In this work, the hydrogen storage behaviors of carbon nanotubes (CNTs)/metal-organic frameworks-5 (MOF-5) hybrid composites (CNTs/MOF-5) were studied. Hydrothermal synthesis of MOF-5 was conducted by conventional convection heating using 1-methyl-2-pyrrolidone (NMP) as a solvent. Morphological characteristics and average size of the CNTs/MOF-5 were also obtained using a scanning electron microscopy (SEM). The pore structure and specific surface area of the CNTs/MOF-5 were analyzed by N2/77 K adsorption isotherms. The capacity of hydrogen storage of the CNTs/MOF-5 was investigated at 298 K/100 bar. As a result, the CNTs/MOF-5 had crystalline structures which were formed by hybrid synthesis process. It was noted that the CNTs/MOF-5 can be potentially encouraging materials for hydrogen adsorption and storage applications at room temperature.