• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1405-1406
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• 2011

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.610-615
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• 2002

Phase formation and proton conduction of L $a_{0.6}$B $a_{0.4}$I $n_{1-y}$ $M_{y}$ $O_{3-{\delta}}$(M=G $a^{3+}$, S $c^{3+}$, Y $b^{3+}$) system were studied. A cubic perovskite structure with a single phase was formed in all of the compositions of this work except for the composition off=G $a^{3+}$ with y=0.5, viz,L $a_{0.6}$B $a_{0.4}$I $n_{1-y}$G $a_{0.5}$ $O_{3-{\delta}}$ For the compositions of M=S $c^{3+}$and Y $b^{3+}$with y=0.25, proton conduction occurred in wet $N_2$ atmosphere(P $h_{H_2O}$=6.1hPa).X>/=6.1hPa).Pa).

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.415-422
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• 2003

BaZr $O_3$-based proton conductors in which B-site cations are partially substituted by Ce and Yb were fabricated by a solid state reaction method. The electrical properties of the specimens were measured by using impedance analyzer in dry air and wet air atmospheres. The electrical conductivity showed higher value in wet air than in dry air at below $600^{\circ}C$. As the Ce content increased, the electrical conductivity increased. Among four compositions, BaZ $r_{0.8}$C $e_{0.15}$Y $b_{0.05}$ $O_3$$_{-{\delta}}$ specimen showed the highest electrical conductivity,1.72$\times$10$^{-3}$ S$cm^{-1}$ /, at 80$0^{\circ}C$. In the low temperature region, the electrical conductivity was higher in wet air than in dry air. However, as the temperature increased, the proton conductivity reduced and thus the electrical conductivity showed similar value at approximately $700^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.59 no.5
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• pp.413-422
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• 2015

Proton exchange membrane (PEM), which transfers proton from the anode to the cathode, is the key component of the proton exchange membrane fuel cell (PEMFC). Nafion is widely used as PEM due to its high proton conductivity as well as excellent chemical and physical stabilities. However, its high cost and the environmental hazards limit the commercial application in PEMFCs. To overcome these disadvantages, various alternative polymer electrolytes have been investigated for fuel cell applications. We used densely sulfonated polymers to maximize the ion conductivity of the corresponding membrane. To overcome high swelling, dipole-dipole interaction was used by introducing nitrile groups into the polymer backbone. As a result, physically-crosslinked membranes showed improved swelling ratio despite of high water uptake. All the membranes with different hydrophilic-hydrophobic compositions showed higher conductivity, despite their lower IEC, than that of Nafion-117.

• Membrane Journal
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• v.25 no.5
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• pp.456-463
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• 2015

In this study, we synthesize novel silane based inorganics for preparation of the polymer electrolyte membrane with high proton conductivity under high temperature condition and developed membranes are characterized. SPAES, hydrocarbon based polymer are synthesized and used as main polymeric material. We used sol-gel method to prepare inorganic material with high performance using silica, phosphate and zirconium. Three types of inorganics were prepared by control of the mole ration of each component. As a result of EDX analysis, the inorganic materials are well dispersed in the polymer membrane. The water uptake of the composite membrane is increased by introduction of the hydrophilic inorganic material in the membrane. When the content of the zirconium in the membrane is increased, the proton conductivity of the composite membrane shows the higher value than pure SPAES membrane at the high temperature. And the silica based inorganics effect to increase the proton conductivity under low temperature condition.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.210-210
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• 2010

ABO2 형태를 가진 delafossite 구조 산화물은 p-type 투명전도체 소재로 유명하다. Delafossite 구조가 p-type 투명전도체에 적합한 결정적인 이유는 밴드갭이 넓고 공유결합에 유리하기 때문이다. 투명전도체는 가시광선의 흡수가 없도록 band gap을 넓히는 것이 우선인데 이러한 band gap이 넓은 구조가 delafossite이다. 또한 delafossite 구조는 구조적으로 각각의 산화물 이온들이 유사 사면체 배위(pseudo-tetrahedral coordination)을 갖는다. 이러한 사면체 배위결합구조에서 산소이온은 비결합면이 없기 때문에 더욱더 공유결합성을 향상시킬 것으로 생각된다. 여기서 A는 +1가 cation, B은 +3가 cation으로 구성되어 있다. A자리에는 1가 원소인 팔라듐, 플래티늄, 은, 구리 등을 가질 수 있고. B자리에 3가 원소이면서도 크기가 알루미늄보다는 크고 란타늄보다는 작은 금속이 들어갈 수 있다. Delafossite 구조는 상온에서 2종류의 polytype (상온에서 Rhombohedaral 구조와 hexagonal 구조)이 존재하며 이들은 각각 3R(Rm) 및2H (P63/mmc)의 결정 구조를 가지고 있다. CuCrO2는 일반적으로 3R결정구조를 가지는 것으로 알려져 있다. delafossite 구조는 전기적 이방성을 띄고 있는데 c-축 방향으로의 전기적 특성이 a-축 방향으로의 전기적 특성보다 약 1000배 높은 물성을 띈다고 한다. 이는 c-축 방향의 원자 위치 때문인데 CuCrO2의 경우 Cu-O-Cr-O-Cu로서 3d-2p-3d-2p-3d 궤도를 가지기 때문인 것으로 알려져 있다.[ref] 반면 c-축으로 에피성장된 박막의 경우 +3가 이온이 위치한 layer에서 hole hopping에 의해 캐리어가 전도된다고 알려져 있기도 하다. 본 연구에서는 PLD를 이용하여 c-plane 사파이어 기판위에 성장된 delafossite구조인 CuCrO2박막의 특성을 알아보았다. p-type 특성을 위하여 CuCrO2에 Ni를 첨가하였으며 그에 따른 구조적 전기적 특성을 조사하였다. 성장온도와 도핑농도를 변화시켜 특성을 연구하였다. 결정구조적 특성과 전기적 특성을 분석하려 한다.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.93-99
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• 2021

In order to decrease the weight of stretchable energy storage devices, interest in developing lightweight materials to replace metal current collectors is increasing. In this study, nanofibers prepared by electrospinning a conductive polymer, PEDOT:PSS, were used as current collectors for lithium ion batteries. The nanofiber showed improved electrical conductivity by using DMSO, a dopant, and indicated a stretch rate of 30% or more from the elasticity evaluation result. In addition, the use of the nanofiber current collector facilitates penetration of the liquid electrolyte and exhibits the effect of increasing the electronic conductivity through the nanofiber network. The lithium-ion battery using the DMSO-doped PEDOT:PSS@PAM nanofiber current collector indicated a high discharge capacity of 135mAh g^-1, and indicated a high capacity retention rate of 73.5% after 1000 cycles. Thus, the excellent electrochemical stability and mechanical properties of conductive nanofibers showed that they can be used as lightweight current collectors for stretchable energy storage devices.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.42-42
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• 1999

본 연구에서는 극 저 에너지 이온 주입에 관한 연구를 위하여 새로이 제안된 PLDAM(phenomenological local damage accumulation model)을 효과적인 분자동역학 이온 주입 분포 계산 방법(highly efficient molecular dynamics (MD) schemes)에 적용하여 극 저 에너지 이온 주입에 관하여 연구하였다. PLDAM은 셀에 축적된 에너지와 이온 발생 순서(history of recoil event) 및 열 전도를 고려하여 실리콘 자기 이완과 재결합을 고려하고 있다. 효과적인 분자동역학 이온 주입방법으로는 MDRANGE code를 사용하였다. 국부적인 격자결함을 고려하지 않은 MDRANGE의 결과는 불순물 분포의 실험치와 꼬리 부분에서 많은 차이를 보여주었다. 그러나 본 연구에서 사용된 국부적인 격자결함 축적을 고려한 MDRANGE의 결과는 극 저 에너지 이온 주입 실험치와 잘 일치하였다. 또한 본 연구에서는 <100> 실리콘 기판 위의 0.1$\mu\textrm{m}$$\times$0.1$\mu\textrm{m}$ 영역에 도즈에 해당하는 이온만큼을 주입하여 불순물 분포를 계산하였다. 붕소와 비소의 경우에, 도즈와 이온주입 에너지가 증가하에 따라서 국부적으로 축적된 격자결함이 불순물의 분포에 미치는 영향이 커지는 것을 알 수 있었다. 특별히 이온 주입 에너지와 함께 무관하게 도즈 1014/cm2 이상에서는 국부적으로 축적된 격자 결함이 불순물의 분포에 크게 영향을 미치는 것으로 나타났다.

• Polymer(Korea)
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• v.24 no.2
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• pp.259-267
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• 2000

Gel polymer electrolytes were prepared from poly(vinylidene fluoride-co-hexafluoro propylene)[P(VdF-co-HFP)] that had higher mechanical properties as well as higher dielectric constant ($\varepsilon$=8~13) than other polymeric matrix. Mechanical properties and ionic conductivities have been investigated as a function of blend ratio of electrolyte solution and polymer matrix. Ethylene carbonate (EC)/${\gamma}$-butyrolactone (${\gamma}$-BL) and lithium triflate (LiCF$_3$SO$_3$) were used as solvent and salt, respectively. The mechanical properties such as tensile strength, tensile modulus, compression modulus, and dynamic shear modulus were evaluated. The highest ionic conductivity was 1.09$\times$10$^{-3}$ S/cm for PVH40 containing 28.6 wt% of P(VdF-co-HFP) at $25^{\circ}C$. Tensile strength, tensile modulus and compression modulus were increased with P(VdF-co-HFP) content and abruptly changed between PVH70 and PVH80. Dynamic shear moduli showed a typical gel behavior and changed with shear strain.

• Membrane Journal
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• v.18 no.4
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• pp.345-353
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• 2008

Organic/inorganic composite electrolyte membranes were prepared for dye sensitized solar cell (DSSC). Polyethylene Glycol (PEG)s with various molecular weight (400, 600, 1,500 and 3,400) was ethoxysilated to fabricate organic/inorganic composite materials through sol-gel processes. The electrolyte membranes were produced by doping the composite materials with NaI and $I_2$, and their ionic conducting behavior was investigated. The ionic conductivity of the composite electrolyte was highly affected by the PEG molecular weight, and the highest conductivity was shown by the composite membrane prepared with PEG with the molecular weight of 1,500. The composite electrolyte membranes showed considerable improvement of ionic conductivity. Compared to PEO electrolyte membranes, the composite electrolyte membrane prepared by PEG, MW 1,500, showed much higher ionic conductivity.