• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.75.2-75.2
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• 2010

Polymer electrolyte fuel cells (PEFCs) have received a lot of attention as a power source for both stationary and mobile applications due to their attractive feature. In general, the performance of PEFCs is highly affected by the property of the electrodes. A PEFC electrode essentially consists of a gas diffusion layer and a catalyst layer. The gas difusion layer is highly porous and hydrophobicized with PTFE polymer. The catalyst layer usually contains electrocatalyst, proton conducting polymer, even PTFE as additive. Particularly, the proton conducting ionomer helps to increase the catalytic activity at three-phase boundary and catalyst utilization. Futhermore, it helps to retain moisture, resulting in preventing the electrodes from membrane dehydration. The most widely used proton conducting ionomer is perfluorinated sulfonic acid polymer, namely, Nafion from DuPont due to its high proton conductivity and good mechanical property. However, there are great demands for alternative ionomers based on non-fluorinated materials in terms of high temperature availability, environmental adaptability and production cost. In this study, the electrodes with the various content of the sulfonated poly(ether sulfone) ionomer in the catalyst layer were prepared. In addition, we evaluated electrochemical properties of the prepared electrodes containing the various amount of the ionomers by using the cyclic voltammetry and impedance spectroscopy to find an optimal ionomer composition in the catalyst layer.

• 전기화학회지
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• 제19권3호
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• pp.107-113
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• 2016

본 연구에서는 고체알칼리 연료전지용 이오노머 바인더 용액 제조를 위하여 poly(2,6-dimethyl-1,4-phenylene oxide)(PPO)를 동결 분쇄하고 4급 암모늄화 반응을 진행하여 음이온 전도성 이오노머(quaternized PPO, QPPO) 용액을 제조하였다. QPPO 이오노머 바인더 용액의 종류를 고분자의 분쇄 시간을 통하여 제조하였고, 이에 따른 분산도, 입자의 크기 및 전기화학적 성능 등을 분석하였다. 이를 통해 기존의 비 분쇄 고분자를 활용하여 제조한 이오노머 바인더 용액보다 분쇄 고분자를 활용한 이오노머 바인더 용액이 높은 고분자 분산도와 낮은 입자 크기를 확보하였다. 제조한 이오노머 바인더 용액(BPPO-G120s)의 최대 이온전도도는 $0.025S\;cm^{-1}$이었으며, 이온교환용량은 $1.26meq\;g^{-1}$을 보였다.

• 대한치과보철학회지
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• 제25권1호
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• pp.227-242
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• 1987

This study was designed to investigate the pulpal effects of the glass ionomer cement. (Lining cement, G-C Co. Japan) For this purpose, 10 cats were selected, and Class V cavities were prepared on canines of the cats. One experimental group was filled with glass ionomer cement and the other group was filled with zinc phosphate cement . (G-C Co, Japan) The animals of the experimental and control group were sacrificed at 1,2,3,4,6, weeks after the experiment. For comparison of reparative dentin formation pattern in direction of the pulpal and fractured lateral surface, each of them was observed with scanning electron microscope. The findings led to the following conclusions; 1. Reparative dentin of the glass ionomer cement and zinc phosphate cement filling groups were formed on the internal surface of dentin as the shape of hemispherical and spherical with a rough surface. 2. Some of reparative dentin of the glass ionomer cement filling group was started to form at 1 week after experiment, and at 6 weeks after experiment, it had been increased gradually in number and size. 3. Reparative dentin of zinc phosphate cement filling group was formed vigorously, however, gradually was decreased in number and size, and disappeared at 6 weeks after experiment. 4. During the formation of reparative dentin, peritubular dentins were indistinguishable. 5. The diameter of dentinal tubules of reparative dentin has been decreased, during the reparative dentin formed, and it became very irregularly at 6 weeks after experiment.

• Restorative Dentistry and Endodontics
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• 제20권1호
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• pp.129-141
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• 1995

Composite resin and glass-ionomer cement can be used for the purpose of repair of defective amalgam restoration. The purpose of this study was to evaluate of shear bond strength of esthetic restorative materials to dental amalgam. The materials used in this study were Photo Clearfil Bright(light curing composite resin), Clearfil F II(chemical curing composite resin), Fuji II LC(light curing glass-ionomer cement), Fuji II (chemical curing glass-ionomer cement), All-Bond 2(intermediary), and Scotchbond Multi-Purpose (intermediary). A total of 120 acrylic cylinders with amalgam were divided into 8 groups After amalgam condensation, all specimens were stored for 48 hours in water at $37^{\circ}C$ and tested with Instron universal testing machine between amalgam and composite resins and glass-ionomer cements. The data were analyzes statiscally by ANOVA and Duncan test. The following results obtained ; 1. The shear bond strength of bonded composite resin to amalgam was higher than bonded glass-ionomer cement(P<.001). 2. The group 4 had highest shear bond strength with 15.45kgf/$cm^2$ and the group 5 had lowest shear bond strenght with 3.26kgf/$cm^2$(P<.001). 3. In the group 3, 4, 5, 6, the group 3, 4 with All-Bond 2 had higher shear bond strength than the group 5, 6 with Scotch bond MP both in light-curing and in chemical curing. 4. Both in composite resin and glass-ionomer cement, chemical curing materials had higher shear bond stength than light curing materials(P<.001).

• Restorative Dentistry and Endodontics
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• 제15권2호
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• pp.1-16
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• 1990

This study was to evaluate the cytotoxic effect in vitro and the tissue response within the rat peritoneal cavity to high copper amalgam and glass ionomer-silver cement, suggested for use as a retrograde endodontic filling material. In the cytotoxicity experiment, the radioactively ($^{51}Cr$) labeled L929 mouse fibroblasts were employed to determine the relative cytotoxicity of two experimental materials. Those materials were evaluated immediately after set and after one and seven days setting. In the tissue response experiment, two experimental materials were to evaluate mean peritoneal cellular count, differential cell count and the content of silver and copper in pooled packed cells and eluate samples taken by peritoneal lavage technique, and compared with surgical control after one day. two, four and six weeks of implantation. The results were as following: 1. High copper amalgam exhibited significant cytotoxicity immediately after set but showed no sign of toxicity after one day and seven days setting materials. 2. Glass ionomer-silver cement showed no sign of toxicity immediately after set and after one day and seven days setting. 3. High copper amalgam and glass ionomer-silver cement groups produce no significant difference in the mean peritoneal cell count when compared with the surgical control group after one day, two and four weeks of implantation. Surgical control group exhibited significantly a greater cell count when compared with the High copper amalgam group after six weeks. 4. High copper amalgam group increased significantly in the percentage macrophages after four and six weeks of implantation when compared with surgical control group. 5. The trace metal analysis involved an increased silver content in the elutes and an increased copper content in the packed cells of high copper amalgam group, and an increased silver content in the packed cells and elutes of glass ionomer-silver cement group.

• 전기화학회지
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• 제6권1호
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• pp.18-22
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• 2003

직접 메탄을 연료전지(DMFC)의 산화극 제조 변수들에 따른 단위전지의 성능변화 관찰 및 특성분석을 수행하였다. 촉매층에서의 이온 전도도에 영향을 주는 이오노머의 양과, 이오노머와 촉매의 결합구조를 결정하는 촉매 슬러리의 용매를 변수로 하였다 전체 이오노머의 비가 0.6일 때 최고 성능을 보였으며 분극 저항도 가장 작게 나타났다. 전기화학적 활성면적도 이오노머가 늘어날수록 증가하였다. 극성이 작은 용매일수록 이오노머가 잘 용해되지 않아 촉매 응집체의 크기가 커졌다 기존의 물이나 알코올 종류의 용매들에 비해 극성이 낮은 DPK $(\varepsilon=12.60)$를 사용하여 제조한 전극이 가장 높은 성능을 보였으며 낮은 분극 저항 값을 가졌다.

• Restorative Dentistry and Endodontics
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• 제14권2호
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• pp.5-19
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• 1989

The purpose of this study was to observe the microleakage of composite resin filling using several glass ionomer cements. The Class V cavities of eighty noncarious human molars were prepared at the cementoenamel juction on the facial and lingual surfaces of each tooth with a No.330 carbide bur in a high speed handpiece. The cavity dimensions were $3.0{\pm}0.5mm$ wide, $2.0{\pm}0.5mm$ high, and $1.5{\pm}0.5mm$ deep and all enamel cavosurface margins were beveled with a No.558 carbide bur in low speed handpiece. The bevel was approximately $45^{\circ}$ and 0.5-1.0mm in width. A total of the 160 cavities was divided into four groups, and then 144 cavities among them were three experimental groups and remaining sixteen cavities were control group. All of the prepared cavities were restored as follows: group 1 : Preparations were restored with there three glass ionomer cements. group 2 : Preparations were restored with a composite resin with three glass ionomer cement bases placed $0.2{\pm}0.1mm$ short of the cavosurface margin. group 3 : Preparations were restored with a composite resin with three glass ionomer cement bases extened to the cavosurface margin. group 4 : As control group, preparations were restored with a composite resin, PALFIQUE. The specimens were then thermocycled in a range of $6^{\circ}C-60^{\circ}C$ and immersed in a bath of 2.0% aqueous basic fuchsin solution for 24 hours. Dye penetration was read on a scale of 0 to 4 by Tani and Buonocore's method. The following conclusions were derived from the results obtained; 1. All groups showed significantly more leakage at the gingival margins than at the occlusal margins(p<0.0005). 2. At the gingival margins, group 1 showed less leakage than group 3(p<0.01) and group 4(p<0.0005), while group 3 exhibited less leakage than group 2(p<0.01) and group 4(p<0.0005). 3. At the occlusal margins, group 4 showed less leakage than group 3(p<0.1) and group 1(p<0.005), while group 3 exhibited less leakage than group 2(p>0.1) and group 1(p<0.025).

• The Journal of Advanced Prosthodontics
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• 제4권3호
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• pp.127-133
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• 2012

PURPOSE. Many dentists use desensitizing agents to prevent hypersensitivity. This study compared and evaluated the effect of two desensitizing agents on the retention of cast crowns when cemented with various luting agents. MATERIALS AND METHODS. Ninety freshly extracted human molars were prepared with flat occlusal surface, 6 degree taper and approximately 4 mm axial length. The prepared specimens were divided into 3 groups and each group is further divided into 3 subgroups. Desensitizing agents used were GC Tooth Mousse and $GLUMA^{(R)}$ desensitizer. Cementing agents used were zinc phosphate, glass ionomer and resin modified glass ionomer cement. Individual crowns with loop were made from base metal alloy. Desensitizing agents were applied before cementation of crowns except for control group. Under tensional force the crowns were removed using an automated universal testing machine. Statistical analysis included one-way ANOVA followed by Turkey-Kramer post hoc test at a preset alpha of 0.05. RESULTS. Resin modified glass ionomer cement exhibited the highest retentive strength and all dentin treatments resulted in significantly different retentive values (In Kg.): GLUMA ($49.02{\pm}3.32$) > Control ($48.61{\pm}3.54$) > Tooth mousse ($48.34{\pm}2.94$). Retentive strength for glass ionomer cement were GLUMA ($41.14{\pm}2.42$) > Tooth mousse ($40.32{\pm}3.89$) > Control ($39.09{\pm}2.80$). For zinc phosphate cement the retentive strength were lowest GLUMA ($27.92{\pm}3.20$) > Control ($27.69{\pm}3.39$) > Tooth mousse ($25.27{\pm}4.60$). CONCLUSION. The use of $GLUMA^{(R)}$ desensitizer has no effect on crown retention. GC Tooth Mousse does not affect the retentive ability of glass ionomer and resin modified glass ionomer cement, but it decreases the retentive ability of zinc phosphate cement.

• Restorative Dentistry and Endodontics
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• 제15권1호
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• pp.120-128
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• 1990

The purpose of this study was to examine the effect of surface treatment on the flexural strength of glass ionomer cement with time elapsed. Glass ionomer cement (Fuji ionomer type II, (GC Co.) was used as experimental materials. Glass ionomer cement was placed in a beam-shaped teflon mold (3mm ${\times}$ 3mm ${\times}$ 25mm) that was rest on a glass plate. Another flat glass was placed on the top of the mold with pressure. After the cement was set, the specimens were divided into three groups and thirty two specimens in each group were surface-treated as follows: No treatment group: Specimens were no surface-treated and stored at $35.6^{\circ}C$ in distilled water. Fuji varnish application (FA) group: Specimens were surface-treated with Fuji varnish (GC Co.) and stored at $35.6^{\circ}C$ in distilled water. Vaseline storage (VS) group: Specimens were no surface-treated and stored at $35.6^{\circ}C$ in vaseline. The flexural strength was measured after I day, 1 week, 2 weeks, 4 weeks from the start of mixing using Instron Universal Testing Instruments. Results were as follows: 1. After 4 weeks, vaseline storage group exhibited the maximum flexural strength (p <0.0005). 2. The flexural strengths in no treatment group were slightly increased with time elapsed, but its difference was not significant, statistically. 3. The flexural strengths in Fuji varnish application group were increased with time elapsed (p <0.05). 4. The flexural strengths in Fuji varnish application group and vaseline storage group were greater than that in no treatment group (p <0.0005).

• 멤브레인
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• 제32권6호
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• pp.475-485
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• 2022

지속적인 화석연료의 과도한 소비는 지구온난화와 기후환경 위기를 초래하고 있다. 이에 따라 화석연료의 대체 에너지 중 수소에너지가 주목받고 있는데, 수소에너지는 공해물질의 배출이 없고 자원적인 제약이 없다는 장점이 있다. 이에 따라 물의 전기분해를 이용하여 수소를 생산하는 수전해 시스템 및 수소에너지를 연료로 사용하여 전기를 생산하는 연료전지 시스템과 관련된 다양한 연구가 진행되고 있다. 본 연구에서는 수전해 시스템과 연료전지의 핵심 소재 중 하나인 음이온 전도성 이오노머 소재를 대상으로 과량의 수화 상태를 반영하여 3D 이오노머 모델을 제작하였다. 최종적으로 과량의 수화상태에서 이오노머의 구조적인 안정성과 성능 분석을 통해, 수전해 시스템과 연료전지의 핵심 소재인 음이온 전도성 이오노머 설계에 있어서 성능향상 인자를 제시하고자 하였다.