• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.135.1-135.1
• /
• 2010

최근 고온에서 사용 가능한 PEMFC용 고분자전해질 막 개발에 대한 연구가 활발히 진행되고 있다. PEMFC가 고온에서 작동하게 되면 높은 성능과 많은 장점을 갖게 된다. PEMFC를 $100^{\circ}C$ 이상에서 운전하게 될 경우 백금 전극 반응을 향상시켜 고가의 백금 촉매 양을 줄일 수 있게 되고, 수소연료 속에 미량 포함된 CO에 의한 촉매표면 피독현상에 대한 내구성을 높일 수 있어 저 순도 수소연료 사용이 가능해 진다. 또한 가습장치와 수소 연료 개질장치의 부피를 줄일 수 있게 되어 전체적인 PEMFC 시스템이 단순화 된다. 현재 연료전지용 고분자 전해질막으로 DuPont사의 과-불소계 고분자 전해질막인 Nafion$^{(R)}$이 가장 널리 사용되고 있다. Nafion$^{(R)}$은 유연한 분자구조 안에 소수성이 강한 주사슬과 친수성을 나타내는 술폰산이 결합된 곁사슬이 존재하여 술폰화 곁사슬의 클러스터 둘레에는 친수성 영역이 형성이 되기때문에 소수/친수 상 분리가 잘되어 이온 클러스터 형성이 용이하지만 제조비용이 높은 단점을 갖고 있다. 특히, 전해질 막내에서 Bronsted base 역할을 하는 물에 의해 이온전도가 이루어지기 때문에 고온에서는 수분증발로 인해 성능이 급격히 감소된다. 따라서, 본 연구에서는 고온 저가습 조건에서 운전이 가능하고 Nafion이 갖는 문제점을 해결하고자, 내열특성이 뛰어나며 높은 수소이온 전도도 학보가 용이한 Sulfonated Poly(aryl ether)sulfone(SPAES) 고분자 전해질에, 고온에서도 수화성이 유지될 수 있도록 지르코니아를 황산화한 sulfated zirconia(s-$ZrO_2$)를 함침하여 복합 고분자전해질막을 제조하여 고온 저가습 조건에서의 수소이온 전도 특성에 관한 연구를 수행하였다. 개발된 막의 물리/화학적 특성은 water content(Wup%), 이온교환 용량(IEC, meq $g^{-1}$), 수소이온전도도(s $cm^{-1}$) 열 중량 분석(TGA), X선 회절분석(XRD) 등을 통하여 분석 및 관찰하였다. 내화학 및 열적 특성분석 결과, 황산화 반응공정으로 $ZrO_2$에 술폰산기가 안정적으로 결합하고 있음이 관찰되었으며, 본 연구에서 개발된 유 무기 복합막이 $250^{\circ}C$이상 열적안정성을 확보하고 있는 것으로 판단되었다. $100^{\circ}C$ 이하의 저온 영역에서, 일정 비율의 s-$ZrO_2$/SPAES막에서 이온교환용량(IEC)이 순수 SPAES 막보다 낮음에도 불구하고, water uptake가 증가함과 동시에 수소이온 전도도가 향상된 것을 관찰하였다. 또한, 고온에서는 수소이온이 자유롭게 이동할 수 있는 water channel을 형성하는 free water는 증발 하지만 s-$ZrO_2$와 SPAES의 술폰산기 사이에 강력하게 결합하고 있는 bound Water는 $100^{\circ}C$ 이상의 고온 영역에서도 존재하여, 비록 무가습 조건에서도 일정 비율의 s-$ZrO_2$/SPAES50 전해질 막의 경우, 높은 전도도를 나타냄을 관찰할 수 있었다. 따라서 본 연구를 통해 저가습 고온 적용을 목적으로 개발된 s-$ZrO_2$/SPAES50막은 우수한 내열 특성을 나타냄과 동시에 저가습 고온 영역($120^{\circ}C$, $50RH{\downarrow}$)에서 높은 수소이온 전도도를 유지하여, 고온 저가습 연료전지 운전에 적합할 것으로 사료된다.

• Polymer(Korea)
• /
• v.30 no.4
• /
• pp.279-285
• /
• 2006

Non-viral gene carriers continue to attract a great deal of interest due to advantageous safety profile. Among the non-viral gene carriers, cationic liposomes or synthetic gene carriers are efficient DNA carriers in vitro. but their in vivo applications are greatly hampered because of low biocompatibility. On the other hand, chitosan, a natural cationic polysaccharide, is a candidate non-viral vector for gene delivery because of its low cytotoxicity and high positive charges. In this work, targeted gene carrier was synthesized to target artery wall cells using low molecular water-soluble chitosan (LMWSC). The molecular weight $(M_W)$ and degree of de acetylation (DDA) of LMWSC were measured by relative viscometer and Kina titration. respectively. The structure of LMWSC was analyzed by measuring FTIR, $^1H-NMR,\;and\;^{13}C-NMR$. AWBP-PEG-g-LMWSC was synthesized by conjugation of the artery wall binding peptide (AWBP), a specific targeting peptide, to the end of pegylated LMWSC as a gene carrier to target artery wall cells. The synthesized AWBP-PEG-g-LMWSC were analyzed by measuring FTIR, $^1H-NMR$, zeta -potentiometer, and atomic force microscopy (AFM).

• Membrane Journal
• /
• v.24 no.4
• /
• pp.301-310
• /
• 2014

In this study, the silica nanoparticles were considerably chosen to improve a dimensional stability, proton transport and electrochemical performance of the resulting inorganic-organic nanocomposite membranes. For this purpose, hydrophobic silica (Aerosil$^{(R)}$ 812, Degussa) and hydrophilic silica (Aerosil$^{(R)}$ 380, Degussa) nanoparticles were, respectively, introduced into a Sulfonated poly(arylene ether sulfone) (SPAES) polymer matrix. The $SiO_2$ particles are evenly dispersed in a SPAES matrix by the aid of a non-ionic surfactant (Pluronics$^{(R)}$ L64). A $SiO_2$ content plays an important role in membrane microstructures and membrane properties such as proton conductivity and water uptake. Therefore, to study nanocomposite membranes with excessive amount of silica, the content of silica nanoparticles were increased up to 5 wt%. Interestingly, a hydrophobic $SiO_2$ containing nanocomposite membrane showed better electrochemical performance (29% higher than pristine SPAES) despite of low proton conductivity due to its adhesive properties with a catalyst layer in a single cell test. All the silica-SPAES membranes exhibited better performance than a pristine SPAES membrane.

• Applied Chemistry for Engineering
• /
• v.18 no.1
• /
• pp.77-83
• /
• 2007

It is essential that second order nonlinear optical materials have low optical propagation losses in the wavelengths of second harmonic generation for practical applications in waveguides. Three dipolar chromophores substituted with nitro, cyano, and alkyl sulfone as an electron withdrawing group were prepared. The UV-Vis absorption spectra of the cyano and alkylsulfone chromophores showed a blue-shift compared to the nitro chromophore. The introduction of oxadiazole segment in the chromophore structure led to similar spectral shift. The blue-shift can produce low optical loses at second harmonics. The chromophores were successfully attached to a polyimide, yielding side chain polymers. The nonlinear optical property of the prepared optical polymers was determined by measuring electro-optic coefficient at 1.55 mm. The polymers exhibited high glass transition temperature of over $185^{\circ}C$ and thermal stability to $300^{\circ}C$ through differential scanning calorimeter analysis and thermal gravimetric analysis.

• Membrane Journal
• /
• v.15 no.4
• /
• pp.310-319
• /
• 2005

This paper describes the preliminary study on the development of multi-stage membrane demonstration plant for removal of carbon dioxide from flue gas stream being emitted from LNG boiler in thermal power generation plant. The prerequisite requirement is to design and develop the membrane process producing a $99\%\;CO_2$ with $90\%$ recovery from LNG flue gas of 1,000 $Nm^3$/day. Asymmetric polyethersulfone hollow fiber membranes and membrane modules developed in this laboratory[1] were used in this study. Using the permeation data for the hollow fiber membranes, modelling on the membrane module and multi-stage membrane process was done to meet the requirement condition of the process design. The effects of the operating pressure of feed and permeate side and feed concentration on $CO_2$ purity and recovery were investigated experimentally with the developed hollow fiber modules. These experimental results matched well with theoretical modelling results.

• Applied Biological Chemistry
• /
• v.26 no.2
• /
• pp.104-109
• /
• 1983

Gas chromatographic method for the analysis of phorate(0,0-diethyl S-ethyl-thiomethyl phosphorithioate) and its metabolites in soil and vegetables was studied by using a mixed phase column(10% DC-200+8% Reoplex-400+2% QF-1 on Gas Chrom Q, $1.8{\times}2mm$ i.d, borosilicate glass column). This column can separate completely phorate and its four metabolites except phoratoxon sulfoxide. Retention time of standard mixture ranged 1.8 to 16.1 minutes at column temperature programming from 130 to $200^{\circ}C$ at $5^{\circ}C/min$ and detector sensitivity was also very high(0.05 to 1.05ng). Recoveries from soil and vegetables untreated but fortified with phorate and its three major metabolites at 0.05 and 0.5ppm levels were above 90% for phorate, phorate sulfoxide and phorate sulfone while recovery of phoratoxon metabolite was about 84%.

• Elastomers and Composites
• /
• v.40 no.2
• /
• pp.136-142
• /
• 2005

Liquid crystalline poly(allylsulfone) networks having $SO_2$ in a main chain and mesogens in a side chain were synthesized and their gas permeability and permselectivity were determined. The monomer II having two allyl groups on the each end group was able to form polymer networks by polymerization reaction, while the monomer I having only one allyl group was not. Molecular motion of the poly(allylsulfone) networks were retarded with increasing the cross-linking density, and the segmental motion of networks was developed enough to show isotropic phase transition. Gas permeabilities of poly(II-5 $01/I-OCH_3$ 99) were 2.58 baller for $O_2$ and 18.4 barrer for $H_2$. It means that hydrogen gas are 7 times more permeable than oxygen. Its permselectivities were high as 23.9 for ${\alpha}(H_2/N_2)$. The permselectivity was increased with increasing the cross-linking density. For example, ${\alpha}(H_2/N_2)$ was 36.8 in poly(II-5 $10/I-OCH_3$ 90), which was shown to be the highest value among these poly(allylsulfone) networks.

• Journal of Veterinary Clinics
• /
• v.18 no.3
• /
• pp.195-200
• /
• 2001

Metabolism and phamacokinetics of albendazole have been studied in Korean native cattle after oral administration of 5 mg/kg of albendazole. As ABZ is known to be rapidly biotransformed to many metabolites in most animal species, it is very imperative to establish the analytical conditions for its metabolites. LC/MS methods for ABZSO and ABZS $O_2$met every requirement enough to study the metabolism of pharmacokinetics of albendazole in Korean native cattle. The parent drug (ABZ) was only measured at first two time points of 0.5 h and 1h, whereas two metabolites were consistently formed between 0.5 h to 48-72 h post-treatment. Formation kinetics for ABZSO and ABZS $O_2$were similar. Time to peak concentration (Tmax) of ABZ-SO appeared at 12h post-treatment of ABZ, faster than that of ABZS $O_2$at 24h. Cmax of ABZS $O_2$(1.05$\pm$0.05 ug/ml) was 1.09 times higher than that of ABZSO (0.96$\pm$0.15). Elimination half-life of ABZS $O_2$(4.2 h) was much shorter than ABZS $O_2$(7.0h) (p<0.005). ABZSO was detected until 48h post-administration but ABZS $O_2$was measurable even at 72h post-dosing. AU $C_{0longrightarrow{\infty}}$ of ABZSO was smaller than that of ABZS $O_2$. Regimen of ABZ is advised to take into consideration is metabolite profiles, especially that of ABZSO, an active metabolite.

• Clean Technology
• /
• v.25 no.1
• /
• pp.91-97
• /
• 2019

Oxidative desulfurization (ODS) has received much attention in recent years because refractory sulfur compounds such as dibenzothiophenes can be oxidized selectively to their corresponding sulfoxides and sulfones, and these products can be removed by extraction and adsorption. In this work, The oxidative desulfurization of marine diesel fuel was performed in a batch reactor with hydrogen peroxide ($H_2O_2$) in the presence of various supported heteropoly acid catalysts. The catalysts were characterized by XRD, XRF, XPS and nitrogen adsorption isotherm techniques. Based on the sulfur removal efficiency of promising silica supported heteropoly acid catalysts, the ranking of catalytic activity was: $30\;H_3PW_{12}/SiO_2$ > $30\;H_3PMo_{12}/SiO_2$ > $30\;H_4SiW_{12}/SiO_2$, which appears to be related with their intrinsic acid strength. The $30\;H_3PW_{12}/SiO_2$ catalyst showed the highest initial sulfur removal efficiency of about 66% under reaction conditions of $30^{\circ}C$, $0.025g\;mL^{-1}$ (cat./oil), 1 h reaction time. However, through the recycle test of the $H_3PW_{12}/SiO_2$ catalyst, significant deactivation was observed, which was attributed to the elution of the active component $H_3PW_{12}$. By introducing cesium cation ($Cs^+$) into the $H_3PW_{12}/SiO_2$ catalyst, the stability of the catalyst was improved with changing the solubility, and the $Cs^+$ ion exchanged catalyst could be recycled for at least five times without severe elution.