• 한국전기전자재료학회논문지
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• 제20권5호
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• pp.421-424
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• 2007

Thermal behavior of $Li_{1-x}CoO_2$ has been investigated employing DSC (Differential Scanning calorimetry) and TGA (Thermogravimetry Analyzer), and the crystal parameters were calculated from XRD (X-ray diffraction).for the commercial rectangular pouch cell(1000 mAh).The cathode materials coated over aluminium foil current collector is made up of a blend consisting of active material $LiCoO_2$(size $20\;{\mu}m$, 94 wt%), conducting material super p black (SPB, 3 wt%) and binder polyvinylidene fluoride (PVDF, 3 wt%). The anode is a mix consisting of carbon (92 wt%) and PVDF(8 wt%) coated over copper foil. The cells for the experiments were first preconditioned by cycling three times and stabilized at OCV=3.0, 3.5, 4.2, 4.35 and 4.5 V. The stabilized cathode material was used for thermal and crystal parameter investigations.

• 한국전기전자재료학회논문지
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• 제17권10호
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• pp.1079-1084
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• 2004

This work describes the effect of electrode binder on the characteristics of electric double layer capacitor. Among carboxymethylcellulose (CMC), Polyvinylpyrrolidone (PVP), Polyvinyl Alcohol (PVA), and Polyvinylidene Fluoride (PVDF), the unit cell using CMC showed good rate capability at current densities between 2.5 mA/$\textrm{cm}^2$～100 mA/$\textrm{cm}^2$. However, CMC as a binder is incongruent, because the electrode bound with CMC is rigid and easy to crack during a press and winding process for fabrication of capacitor. The unit cell capacitor using the electrode bound with binary binder composed of CMC and Polytetrafluoroethylene (PTFE), especially in composition CMC : PTFE =60 : 40 wt.%, has exhibited the better mechanical properties than those of the unit cell with CMC. On the other hand, the mechanical properties of CMC+PTFE electrode, coated on underlayer composed of CMC and carbon black, were much improved.

• 한국세라믹학회지
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• 제53권6호
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• pp.700-706
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• 2016

Etch rate, surface roughness and microstructure as plasma resistance were evaluated for six kinds of oxide glass with different compositions. Borosilicate glass (BS) was found to be etched at the highest etch rate and zinc aluminum phosphate glass (ZAP) showed a relatively lower etch rate than borosilicate. On the other hand, the etching rate of calcium aluminosilicate glass (CAS) was measured to be similar to that of sintered alumina while yttrium aluminosilicate glass (YAS) showed the lowest etch rate. Such different etch rates by mixture plasma as a function of glass compositions was dependent on whether or not fluoride compounds were formed on glass and sublimated in high vacuum. Especially, in view that $CaF_2$ and $YF_3$ with high sublimation points were formed on the surface of CAS and YAS glasses, both CAS and YAS glasses were considered to be a good candidate for protective coating materials on the damaged polycrystalline ceramics parts in semi-conductor and display processes.

• 한국전기전자재료학회논문지
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• 제26권8호
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• pp.620-623
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• 2013

The carbon nanotube / poly-vinylidene fluoride (CNT/PVDF) composite films for the nano-generator devices were fabricated by spray coating method using the CNT/PVDF solution, which was prepared by adding PVDF pellets into the CNT dispersed N-Methyl-2-pyrroli-done (NMP) solution. The flexible CNT/PVDF composite films were investigated by the scanning electron microscopy, which revealed that the CNTs were uniformly dispersed in the PVDF matrix and thickness of the films was approximately $20{\mu}m$. Fourier transform infra-red spectra were used to investigate crystal structure of the as-spray-coated CNT/PVDF films, and we found that they revealed extremely large portion of the ${\beta}$ phase PVDF. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the resistance didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Finally, the resulting nano-generator devices revealed reasonable current output after given mechanical stress.

• ETRI Journal
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• 제35권4호
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• pp.734-737
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• 2013

Nonvolatile ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) memory based on an organic thin-film transistor with inkjet-printed dodecyl-substituted thienylenevinylene-thiophene copolymer (PC12TV12T) as the active layer is developed. The memory window is 4.5 V with a gate voltage sweep of -12.5 V to 12.5 V. The field effect mobility, on/off ratio, and gate leakage current are 0.1 $cm^2/Vs$, $10^5$, and $10^{-10}$ A, respectively. Although the retention behaviors should be improved and optimized, the obtained characteristics are very promising for future flexible electronics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.512-513
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• 2007

Carbon/polymer based composite electrodes were fabricated by using Super p. Black(SPB) as a conductor and polyvinylidene fluoride (PVDF) as a binder. This type of composite electrode are considered as excellent candidates for heating film and variable resistor applications. Aim of this work is the study of the Mechanical and Electrical properties on composite electrode by the contents of SPB and MWCNT, respectively. The composite electrode having 10~15 wt% of SPB show good electrical and mechanical properties. Mechanical and electrical properties are increased by the addition of MWCNT into the composite electrode.

• 열처리공학회지
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• 제25권2호
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• pp.65-73
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• 2012

The Gas Diffusion Layer (GDL) of fuel cell, are required to provide both delivery of reactant gases to the catalyst layer and removal of water in either vapor or liquid form in typical PEMFCs. In this study, the fabrication of GDL containing Micro Porous Layer (MPL) made of the slurry of PVDF mixed with carbon black is investigated in detail. Physical properties of GDL containing MPL, such as electrical resistance, gas permeability and microstructure were examined, and the performance of the cell using developed GDL with MPL was evaluated. The results show that MPL with PVDF binder demonstrated uniformly distributed microstructure without large cracks and pores, which resulted in better electrical conductivity. The fuel cell performance test demonstrates that the developed GDL with MPL has a great potential due to enhanced mass transport property due to its porous structure and small pore size.

• 공업화학
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• 제32권3호
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• pp.290-298
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• 2021

천연 흑연의 음극재 적용을 위하여 정제 공정을 실시하였으며, 공정에 따른 흑연의 구조적 변화와 불순물 함량이 음극 특성에 미치는 영향을 고찰하였다. 천연 흑연은 불화암모늄과 황산을 동일 비로 하여 사용량을 달리한 산처리 및 온도(800~2500 ℃)를 달리한 열처리를 통하여 화학적/물리적으로 정제되었다. 산을 이용한 불순물 제거는 한계가 있었으며, 이후 진행된 2500 ℃까지의 열처리를 통해 Si과 같은 일부 원소를 제외하고 대부분의 불순물이 전량 제거되는 것을 확인하였다. 복합 정제 공정에 따라 제조된 흑연 음극재의 특성이 향상되었으며, 구조와 불순물 함량 변화는 각각 용량 및 속도 특성과 초기 쿨롱 효율에 지배적인 영향을 미쳤다. 복합 정제 공정은 흑연 구조를 향상시켰으며, 불순물을 효율적으로 제거하여 SEI층 형성 억제 및 Li⁺ 삽입 공간 확대를 통해 리튬 이온 전지의 성능을 향상시켰다.

• 한국미생물·생명공학회지
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• 제5권4호
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• pp.177-184
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• 1977

Arylsulfatase는 간단한 Phenols류의 황에스테르 화합물로부터 S $O_{4}$$^{[-992]}$ - 이온의 유리를 촉매한다. 이 효소는 토양센균을 포함한 많은 미생물과 동식물의 조직등에 널리 분포하여 있으며 이와 같은 넓은 분포는 이 효소의 기본적 기능이 환경학적으로 매우 중요한 의미를 갖는다고 하겠다. Arylsulfatase에 대한보고는 Klebsiella sp를 사용하여 몇몇 보고가 있다. 본 연구는 6종의 Serratia sp를 사용하여 arylsulfatase 합성조건을 검토하고 효소의 정제조건과 성질에 대하여 조사하여 Serratia marcescens를 선정하였다. Serratia mrcescens는 탄소원으로서 xylose rhamnose, glucosamine 그리고 arabinose등과 같은 몇몇 당을 이용하지 못했으며 glucose와 mannitol을 잘 이용하였으나 glucose methioniue의 경우 효소 합성을 억제시키었다. 유황원으로서는 무기유황염과 methionine의 첨가는 억제되었으며 tyramine의 첨가에 의해서 효소 함성의 억제효과는 해제되었다. 효소의 정제는 황산암모늄 포화용액의 분획과 DEAE-Cellulose, CM-Cellulose 그리고 DEAE-Sephadex A-25로 연결되는 구분 분획에 의해서 행하여졌다. 효소의 분자량은 SDS-gelelectrophoresis와 Sephadex G-100 column chromatography에 의하여 각각 46,000과 49,000으로 측정되었고 최적 PH는 6.8이었다. P-Nitrophenyl sulfate를 사용한 Km과 Vmak치는 각각 2.5$\times$$10^{4-}$M과 20 nmoles/min/mg protein이었다. 기질에 대한 특성은 phenylsulfte와 ο-, p-nit-rophenyl sulfate 그리고 p-nitro catechol sulfate에 대해서 높은 활성을 보였다. Hydroxylamine, inorganic fluoride, sulfide 그리고 Phosphate등은 강한 효소 저해작용을 나타내었고 무기유산염은 저해작용을 보여주지 않았다. Tyramine, octopamine그리고 dopamine과 같은 amino acid 또한 강한 저해 작용을 보였다.

• 자원리싸이클링
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• 제11권1호
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• pp.3-8
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• 2002

고탄소페로망간을 중저탄소페로망간으로 제조하는 AOD공정에서 발생되는 분진은 약 90%가 $Mn_3$$O_4$이므로, 이를 이용하여 soft ferrite의 원료인 고순도 $Mn_3$$O_4$분말을 제조하기 위해서는 침출한 액의 Mn을 더욱 정제하여야 한다. 분진을 활성탄으로 배소하여 MnO로 환원시키고, 상온의 4N 염산수용액에 180g/L의 환원된 분진을 첨가하면 용액의 pH가 5이상이 되고 Fe와 Si가 침전으로 제거된 약 10%의 망간침출액이 얻어진다. Mn의 농도가 약 15000 ppm이 되도록 희석한 $70^{\circ}C$의 침출액에 F의 농도가 3000ppm이 되도록 $NH_4$F를 첨가하면 Ca가 침전하여 약14 ppm이하로 제거된다. Ca를 침전시킨 상징액에(NH$ 1.5M_4$)$_2$$CO_3$수용액을 2L/min으로 Mn의 당량만큼 첨가하면 미립의 고순도 $MnCO_3$가 침전한다. 침전을 여과하고 건조한 후에 $1000^{\circ}C$에서 2 시간 소성하면 median size가 $8.2mu$m인$ Mn_3$O$_4$를 얻을 수 있다. 제조된 산물은 99%이상의 순도로 soft ferrite용 Mn$O_3$$_4$분말의 규격을 만족한다.