• 멤브레인
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• 제28권3호
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• pp.180-186
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• 2018

Polyvinylidene fluoride (PVDF)의 중공사막 표면에 2번 딥코팅하여 layer-by-layer 방식으로 나노복합막을 제조하였다. 1차 코팅에서 poly(vinylsulfonic acid)(PVSA)와 Poly(styrene sulfonic acid)(PSSA)의 농도, 이온세기(Ionic strength, IS) 등을 변화시키며 막을 제조하였으며, 2차 코팅 용액으로는 Poly(ethyleneimine) 10,000 ppm I.S = 0.3으로 고정하였다. 막의 특성평가를 위해 각각의 100 ppm NaCl, $CaSO_4$, $MgCl_2$, 그리고 25 ppm Methyl Orange (MO) 공급액에 대한 막의 투과도와 염배제율을 측정하였다. 코팅용액의 코팅 물질의 농도가 올라갈수록 염배제율이 상승하였으며, 본 실험 조건에서 PVSA보다는 PSSA를 이용하여 제조한 중공사막이 염배제율이 높은 것을 확인하였다. 대표적으로 PSSA 30,000 ppm I.S = 1.0에서 중 공사막을 제조하였을 때 25 ppm MO용액의 투과도 1.848 LMH, 염배제율 76.3%로 가장 높은 값을 나타내었다.

• 멤브레인
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• 제28권5호
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• pp.361-367
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• 2018

본 연구에서는 polyvinylidene fluoride (PVDF) 중공사막을 지지체로 한 저압용 나노복합막을 제조하였다. Poly styrene sulfonic acid (PSSA)와 polyethyleneimine (PEI)을 layer-by-layer 및 염석 효과 방식으로 지지체막에 코팅하였다. 막의 투과도와 염 배제율 성능을 알아보고자 NaCl, $MgCl_2$, $CaSO_4$ 100 mg/L수용액을 1 L/min의 유량으로, 2 bar의 압력을 상온에서 가해주었다. 20,000 ppm의 PSSA (이온세기 1.0)용액에 3분, 30,000 ppm (이온세기 0.1)용액에 1분 코팅한 막이 가장 우수하였다. 투과도와 염 배제율은 NaCl 공급액에서는 38.5 LMH, 57.1%, $MgCl_2$는 37.9 LMH, 90.2%, $CaSO_4$는 32.4 LMH, 54.6%로 각각 측정되었다.

• Journal of Electrical Engineering and Technology
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• 제13권4호
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• pp.1692-1696
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• 2018

Ferroelectric $BaTiO_3$/poly(vinylidene fluoride) (PVDF) nanocomposite films were successfully prepared by mixing $BaTiO_3$ nano-particles into PVDF solution dissolved in dimethylformamide under ultrasonification. The mixture was casted onto glass petri dish and then annealed at $100^{\circ}C$ for 12 h in vacuum dry oven. Crystal structure and surface morphology of the samples were analyzed by using an X-ray diffraction analysis and a field emission-scanning electron microscope, respectively. The relative dielectric permittivity and loss tangent were determined in the frequency range of 50 Hz to 1 MHz. For the $BaTiO_3/PVDF$ nanocomposites, the entire diffraction peaks match those indicated by standard $BaTiO_3$ perovskite structure. The FE-SEM image reveals the homogeneity of the $BaTiO_3$ nanopowder distribution and also predominant 0-3 connectivity. All results show that the dielectric properties of the nanocomposite films are desirable and the fabrication technique for preparing the $BaTiO_3/PVDF$ nanocomposites has a potential in the electronic applications.

• 대한방사성의약품학회지
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• 제5권1호
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• pp.48-53
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• 2019

A bone metastasis is an important factor for prognosis and treatment of breast or prostate cancer patients. [$^{18}F$]Sodium fluoride ([$^{18}F$]NaF) is a PET radiopharmaceutical that can detect bone metastasis. Conventional [$^{18}F$]NaF production process included radioactive metal impurities because the product was prepared by adding saline after beam irradiation to $[^{18}O]H_2O$. In this study, we apply the method of removing radionuclidic impurities. To meet the criteria prescribed by GMP in quality control, we designed the custom-made [$^{18}F$]NaF automatic module. The mean radiochemical yield was $82.1{\pm}4.4%$ (n = 32) productions for 3 years) and the total preparation time was 4 min. The final produced [$^{18}F$]NaF solution meets the USP criteria for quality control. Thus, this fully automated system is validated for clinical use.

• 한국물환경학회지
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• 제28권1호
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• pp.148-156
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• 2012

In this research, the application of carbon nanotubes (CNTs) modified PVDF (polyvinylidene fluoride) membrane was tested as a simply and beginning attempt to overcome membrane fouling because CNTs importantly affect the transport of natural organic matter (NOM). Suwannee River fulvic acid (SRFA) as the representative of NOM was selected and its sorption results with single-walled CNT (SWCNT), multi-walled CNT (MWCNT), and oxidized MWCNT (O-MWCNT) were obtained through the batch experiment. SRFA sorption isotherms had a strong nonlinearity and its sorption capacity followed the order O-MWCNT < MWCNT < SWCNT. The adsorbed mass of SRFA on each CNT decreased as a function of pH due to their charge repulsion. For the CNT-PVDF membrane filtration experiments, the suspended CNT solution (10 mg/40 mL) was incorporated into $0.45{\mu}m$-PVDF membrane and 5 mg/L of SRFA solution was monitored using UV detector connected with high pressure pump after passing through CNT-PVDF membrane. The SRFA removal efficiency by MWCNT-PVDF membrane was the strongest among other modified membranes. This suggests that the CNT modified microfiltration (MF) membrane might effectively and selectively apply to treat the contaminated water including organic compounds in the presence of NOM.

• The Korean Journal of Physiology and Pharmacology
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• 제14권1호
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• pp.51-57
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• 2010

It was hypothesized that NaF induces calcium sensitization in $Ca^{2+}$-controlled solution in permeabilized rat mesenteric arteries. Rat mesenteric arteries were permeabilized with $\beta$-escin and subjected to tension measurement. NaF potentiated the concentration-response curves to $Ca^{2+}$ (decreased $EC_{50}$ and increased $E_{max}$). Cumulative addition of NaF (4.0, 8.0 and 16 mM) also increased vascular tension in $Ca^{2+}$-controlled solution at pCa 7.0 or pCa 6.5, but not at pCa 8.0. NaF-induced vasocontraction and $GTP{\gamma}S$-induced vasocontraction were not additive. NaF-induced vasocontraction at pCa 7.0 was inhibited by pretreatment with Rho kinase inhibitors H1152 or Y27632 but not with a MLCK inhibitor ML-7 or a PKC inhibitor Ro31-8220. NaF induces calcium sensitization in a $Ca^{2+}$ dependent manner in $\beta$-escin-permeabilized rat mesenteric arteries. These results suggest that NaF is an activator of the Rho kinase signaling pathway during vascular contraction.

• Membrane and Water Treatment
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• 제7권5호
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• pp.377-401
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• 2016

To study the effect of titanium dioxide ($TiO_2$) nanoparticles on membrane performance and structure and to explore possible improvement of using mixed solvents in the casting solution, composite polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared via immersion precipitation method using a mixture of two solvents triethyl phosphate (TEP) and dimethylacetamide (DMAc) and addition of $TiO_2$ nanoparticles. Properties of the neat and composite membranes were characterized using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), Atomic force microscopy (AFM) and contact angle and membrane porosity measurements. The neat and composite membranes were further investigated in terms of BSA rejection and flux decline in cross flow filtration experiments. Following hydrophilicity improvement of the PVDF membrane by addition of 0.25 wt.% $TiO_2$, (from $70.53^{\circ}$ to $60.5^{\circ}$) degree of flux decline due to irreversible fouling resistance of the composite membrane reduced significantly and the flux recovery ratio (FRR) of 96.85% was obtained. The results showed that using mixed solvents (DMAc/TEP) with lower content of $TiO_2$ nanoparticles (0.25 wt.%) affected the sedimentation rate of nanoparticles and consequently the distribution of nanoparticles in the casting solution and membrane formation which influenced the properties of the ultimate composite membranes.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.115-116
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• 2008

The ferroelectric vinylidene fluoride-trifluoroethylene ($VF_2$-TrFE) and $Al_2O_3$ passivation layer for the Metal/Insulator/Ferroelectric/Semiconductor (MIFS) structure were deposited using spin coating and remote plasma atomic layer deposition (RPALD), respectively. A 2.5 ~ 3 wt % diluted solution of purified vinylidene fluoride-trifluoroethylene ($VF_2$: TrFE=70:30) in a DMF solution were prepared and deposited on silicon wafer at a optimized spin speed. After annealing in a vacuum ambient at 150 ~ $200^{\circ}C$ for 60 min, upper insulator layer were deposited at temperature ranging from 100 ~ $150^{\circ}C$ by RPALD. We described electrical and structural properties of MIFS fabricated by spin coating and RPALD methods.

• Nuclear Engineering and Technology
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• 제49권3호
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• pp.541-548
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• 2017

Uranium metal used for fabrication of fuel for research reactors in India is generally produced by magnesio-thermic reduction of $UF_4$. Performance of magnesio-thermic reaction and recovery and quality of uranium largely depends on properties of $UF_4$. As ammonium diuranate (ADU) is first product in powder form in the process flow-sheet, properties of $UF_4$ depend on properties of ADU. ADU is generally produced from uranyl nitrate solution (UNS) for natural uranium metal production and from uranyl fluoride solution (UFS) for low enriched uranium metal production. In present paper, ADU has been produced via both the routes. Variation of uranium recovery and crystal structure and composition of ADU with progress in precipitation reaction has been studied with special attention on first appearance of the precipitate Further, ADU produced by two routes have been calcined to $UO_3$, then reduced to $UO_2$ and hydroflorinated to $UF_4$. Effect of two different process routes of ADU precipitation on the characteristics of ADU, $UO_3$, $UO_2$ and $UF_4$ were studied here.

• 대한소아치과학회지
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• 제34권4호
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• pp.613-622
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• 2007

본 연구의 목적은 법랑질 시편에 수종의 불소 제재를 도포한 후 우식 예방 효과를 광밀도 및 미세경도 측정을 통해 평가하는 것이다. 소의 절치를 이용하여 80개의 법랑질 시편을 제작하고 각 군당 20개씩, 네 군으로 나누었다. I군은 대조군으로서 아무런 처치도 하지 않았고 II군은 acidulated phosphate fluoride(APF) gel(60 seconds $taste^{(R)}$, PASCAL, USA)을 4분간 적용한 후 수세하였다. III군은 Fluor $Protector^{(R)}$(Ivoclar Vivadent, Liechtenstein)를, IV군은 $CavityShield^{TM}$(Omnii Pharmaceuticals, USA)를 1분간 도포하고 증류수에 보관한 뒤 24시간 후 부드러운 모를 가진 칫솔을 이용하여 칫솔질하였다. 각 시편을 인공우식용액에 48시간동안 침잠시켜 인공우식병소를 유발한 후 광밀도를 컴퓨터 영상분석 프로그램으로 분석하고 표면미세경도를 측정하여 다음의 결과를 얻었다. 1. 광밀도는 APF gel을 도포한 II군에 비해 불소 바니쉬를 도포한 III, IV군이 높았으나(p<0.05) III군과 IV군 사이의 유의한 차이는 없었다. 2. 표면미세경도는 IV군, III군, II군, I군의 순으로 높았다(p<0.05). 3. $CavityShield^{TM}$를 도포한 IV군과 Fluor $Protector^{(R)}$를 도포한 III군은 광밀도에서는 유의한 차이가 없었으나 표면 미세경도는 IV군이 III군보다 유의하게 높았다. 이상의 결과를 종합해 볼 때 불소 바니쉬가 APF gel에 비해 법랑질 탈회 억제 효과가 우수한 것으로 나타났다. 임상적용의 용이성과 안전성을 고려할 때 불소 바니쉬의 사용이 영유아나 장애인에게 유용할 것으로 사료된다.