• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1518-1520
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• 2000

Amorphous $MnO_{2}{\cdot}nH_{2}O$ in 1M KOH aqueous electrolyte proves to be an excellent electrode for a faradic electrochemical capacitor cycled between -0.5 and +1.0 versus Ag/AgCl. The effect of thermal treatment on the crystalinity, particle structure, and corresponding electrochemical properties of the resulting xerogel remained amorphous as Mn(OH)2 up to 160$^{\circ}C$. With an increase in the temperature above 200$^{\circ}C$, both the surface area and pore volume decreased sharply, because the amorphous Mn(OH)2 decomposed to form MnO that was subsequently oxidized to form crystalline Mn3O4. In addition, the changes in the crystallinity, and particle structure all had significant but coupled effects on the electrochemical properties of the xerogels. A maximum capacitance of 160.6F/g was obtained for an electrode prepared with the MnOx Xerogel calcined at 150$^{\circ}C$, which was consistent with the maxima exhibited in both the surface area and pore volume. This capacitance was attributed solely to a surface redox mechanism.

• 청정기술
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• 제21권1호
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• pp.62-67
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• 2015

본 연구에서는 그래핀과 다중벽 탄소나노튜브를 포함하는 하이브리드 소재의 제조 및 슈퍼캐패시터 전극물질로의 활용에 관한 내용이 진행되었다. 이를 위하여 산화그래핀과 아민(-NH₂) 그룹이 치환된 다중벽 탄소나노튜브를 산 촉매 하에서 반응시켜, 새로운 이민(-C=N-) 결합이 도입된 하이브리드 복합체를 합성하였다. 상기 제조된 하이브리드 소재를 슈퍼캐패시터 전극 물질로 사용하고자 수산화칼륨 전해질 기반의 3상 전극 시스템을 활용하여 전기화학적 특성을 살펴보았다. 또한 하이브리드 소재에 존재하는 그래핀과 다중벽 탄소나노튜브의 비율 변화 실험을 통하여, 그래핀/탄소나노튜브의 질량비가 7.5/1일 때 그 특성이 최적화가 됨을 알 수 있었다. 최적화된 전극은 높은 비축천용량(132 F/g)을 나타내었을 뿐만 아니라, 반복된 충방전 실험에서 높은 안정성(95%, retention after 5000 cycles)을 나타내었다.

• 한국표면공학회지
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• 제55권1호
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• pp.32-37
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• 2022

In a carbon-zero social atmospher, research is underway to reduce the use of fossil fuels. Interest in cleaner energy sources and their storage system is growing, and among them, research on effective energy storage is being actively conducted. Energy storage system(ESS) can be divided into secondary batteries, fuel cells, and capacitors, and the superiority of energy density of secondary batteries has a dominent influence on the ESS market. However, as problems with secondary batteries, charge/discharge speed, safety, and deterioration of electrodes are being highlighted. In this study, an electrode for supercapacitor with superior charge/discharge speed and specific capacitance is manufactured. The manufactured spinel nickel cobalt electrodes had specific capacitances of 1018.8 F/g, 690.8 F/g, and 475.1 F/g at 1 A/g in 1 M KOH electrolyte, and shows a performance retention rate of 77.48%, 63.30%, and 58.16% after 2000cycles at 7 A/g.

• 한국재료학회지
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• 제32권9호
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• pp.369-378
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• 2022

The recycling of solid waste materials to fabricate carbon-based electrode materials is of great interest for low-cost green supercapacitors. In this study, porous carbon foam (PCF) was prepared from waste floral foam (WFF) as an electrode material for supercapacitors. WFF was directly carbonized at various temperatures of 600, 800, and 1,000 ℃ under an inert atmosphere. The WFF-derived PCF (C-WFF) was found to have a specific surface area of 458.99 m²/g with multi-modal pore structures. The supercapacitive behavior of the prepared C-WFF was evaluated using a three-electrode system in a 6 M KOH aqueous electrolyte. As a result, the prepared C-WFF as an active material showed a high specific capacitance of 206 F/g at 1 A/g, a rate capability of 36.4 % at 20 A/g, a specific power density of 2,500 W/kg at an energy density of 2.68 Wh/kg, and a cycle stability of 99.96 % at 20 A/g after 10,000 cycles. These results indicate that the C-WFF prepared from WFF could be a promising candidate as an electrode material for high-performance green supercapacitors.

• Journal of the Korean Wood Science and Technology
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• 제50권4호
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• pp.219-236
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• 2022

Wood-based nanocomposite electrode materials were synthesized for application in supercapacitors by mixing nanostructured hematite (Fe₂O₃) with highly porous activated carbon (AC) produced from the wood-waste of Pinus roxburghii. The AC was characterized using various instrumental techniques and the results showed admirable electrochemical properties, such as high surface area and reasonable porosity. Firstly, AC was tested as an electrode material for supercapacitors and it showed a specific capacitance of 59.02 Fg^-1 at a current density of 1 Ag^-1, cycle life of 84.2% after 1,000 cycles (at a current density of 3 Ag^-1), and energy density of 5.1 Wh/kg at a power density of 135 Wkg^-1. However, when the AC was composited with different ratios of Fe₂O₃ (1:1, 2:1, and 1:2), there was an overall improvement in its electrochemical performance. Among the 3 ratios, 2:1 (AC:Fe₂O₃) had the best specific capacitance of 102.42 Fg^-1 at 1 Ag^-1, cycle life of 94.4% capacitance after 1,000 cycles (at a current density of 3 Ag^-1), and energy density of 8.34 Wh/kg at a power density of 395.15 Wkg^-1 in 6 M KOH electrolyte in a 3-electrode experimental setup with a high working voltage of 1.55 V. Furthermore, when Fe₂O₃ was doubled, 1:2 (AC:Fe₂O₃), the electrochemical capacitive performance of the electrode twisted and deteriorated due to either the accumulation of Fe₂O₃ particles within the composite or higher bulk resistance value of pure Fe₂O₃.

• 전기화학회지
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• 제10권2호
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• pp.132-140
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• 2007

백금족/수용액 계면에서 Langmuir, Frumkin, Temkin 흡착등온식(${\theta}\;vs.\;E$)을 결정하기 위해 최적중간주파수 일 때 위상이동($0^{\circ}{\leq}-{\varphi}{\leq}90^{\circ}$) 거동($-{\varphi}\;vs.\;E$)과 표면피복율($1{\geq}{\theta}{\geq}0$) 거동(${\theta}\;vs.\;E$) 사이의 선형 관계식 연구에 관한 위상이동 방법 및 상관계수를 제안하고 증명하였다. Ir/0.1 M KOH수용액 계면에서 음극 $H_2$ 발생 반응에 관한 수소의 Langmuir 및 Temkin 흡착등온식(${\theta}\;vs.\;E$), 평형상수(Langmuir 흡착등온식: $K=3.3{\times}10^{-4}mol^{-1}$, Temkin 흡착등온식: $K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}$), 상호작용 파라미터(Temkin 흡착등온식: g=4.6), 표준자유에너지($K=3.3{\times}10^{-4}mol^{-1}$ 일 때 ${\Delta}G_{ads}^0=19.9kJ\;mol^{-1},\;K=3.3{\times}10^{-3}{\exp}(-4.6{\theta})\;mol^{-1}$ 및 $0.2<{\theta}<0.8$일 때 $16.5<{\Delta}G_{\theta}^0<23.3kJ\;mol^{-1}$)를 결정한다. 수소 흡착부위의 비균일 및 측 방향 상호작용 효과는 무시할 수 있다. ${\theta}$의 중간값 즉, $0.2<{\theta}<0.8$일 때 Langmuir 또는 Frumkin 흡착등온식과 상관관계에 있는 Temkin 흡착등온식은 상관계수를 이용하여 쉽게 결정할 수 있다. 위상이동 방법 및 상관계수는 흡착동온식(${\theta}\;vs.\;E$) 및 연관된 전극속도론과 열역학 파라미터(K, g, ${\Delta}G_{ads}^0, {\Delta}G_{\theta}^0$)를 결정하기 위한 정확하고 확실한 기술 및 방법이다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.64.1-64.1
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• 2010

The morphology of mesoporous $TiO_2$ films plays an important role in the operation of a DSSC. For example, the energy conversion efficiency of DSSCs with well-organized mesoporous $TiO_2$ films is much higher than those with traditional films possessing a random morphology. In previous research, well-organized mesoporous $TiO_2$ films have mainly been synthesized using an amphiphilic block copolymer, e.g., a poly(ethylene oxide) (PEO)-based template. A graft copolymer is more attractive than a block copolymer due to its low cost and the ease with which it can be synthesized. In this work, we provide the first report on the successful synthesis of well-organized mesoporous $TiO_2$ films templated by an organized graft copolymer as a structure directing agent. Well-organized mesoporous $TiO_2$ films with excellent channel connectivities were developed via the sol gel processusing an organized PVC-g-POEM graft copolymer synthesized by one-pot ATRP. The careful adjustment of copolymer composition and solvent affinity using a THF/$H_2O$/HCl mixture was used to systematically vary the material structure. The influence of the material structure on solar cell performance was then investigated. A solid-state DSSC employing both the graft copolymer templated organized 700 nm-thick $TiO_2$ films and graft copolymer electrolytes exhibited a solar conversion efficiency of 2.2% at 100 $mW/cm^2$. This value was approximately two-fold higher than that attained from a DSSC employing a random mesoporous $TiO_2$ film. The solar cell performance was maximized at 4.6% when the film thickness was increased to $2.5{\mu}m$. We believe that this graft copolymer-directed approach introduces a new and simple route toward the synthesis of well-organized metal oxide films as an alternative to a conventional block copolymer-based template.

• Journal of Acupuncture Research
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• 제21권1호
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• pp.136-148
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• 2004

Objective: Recently scolopendrid aquacupuncture has been a good effect on pain control but it has not been known about clinical safety. So, In order to prove the clinical safety of scolopendrid aquacupuncture, We have observed the physical reac-tion and clinical pathology test after scolopendrid aquacupuncture treatment. Methods: We analyzed physical reaction and clinical pathology test before and after Scolopendrid aquacupuncture treatment of 30 patients suffering from pain, who admitted department of Acupunture and Moxibustion, College of Oriental Medicine, Won-Kwang University Kwangju hospital. Results & Conclusions: The results were summarized as follows. 1) The distribution of sex was 14 males and 16 females, and the average of patients age was 46.2 years. 2) The distribution of symptom was lumbago, lumbago with radiating pain, nuchal pain and knee joint pain. 3) In the 30 patients treated with Scolopendrid aquacupuncture, hematologic test did not show remarkable change. 4) In the 30 patients treated with Scolopendrid aquacupuncture, Liver function test(AST, ALT, ALP) showed a slight decrease on the contrary, and abnormal rate showed a decrease of 1.0%(from 3.3% to 2.3%) compared with previous study. 5) In the 30 patients treated with Scolopendrid aquacupuncture, Renal function test(BUN, Cr) and abnormal rate(from 2.5% to 2.0%) showed a slight decrease on the contrary. 6) In the 30 patients treated with Scolopendrid aquacupuncture. Electrolyte were normal range before & after treatment. 7) In the results of the Urine analysis of 30 patients, Leukocyte, Protein. Glucose, Keton, Bilirubin, U-bilinogen were not detected before and after Scolopendrid aquacupuncture treatment, and the rest almost made no difference. 8) In the Physical reactions, all of the patients complained of pain of body partially, only one patient showed reddish and itch, but symptoms like those were entirely disappeared within 24 hours and whole body pain, swelling, headache, dizziness, fatigue and nausea was not observed.

• 한국결정성장학회지
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• 제24권2호
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• pp.59-64
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• 2014

전해질로 $Na_2SiO_3$을 사용하여 A1050 알루미늄 판재를 pulse 폭 $ 2000{\mu}sec$, impulse 420 V, 400 ${\mu}$sec의 unipolar pulse로 플라즈마 전해 산화 코팅(plasma electrolytic oxidation coating)을 하여 산화 피막을 2, 5, 15, 30분에 따라 형성시킨 다음 산화피막을 분석하였다. 표면에 형성된 산화물의 결정상은 ${\alpha}-alumina$와 ${\gamma}-Alumina$로서 시간에 따른 변화는 없었다. 반응 초반에는 ${\gamma}-Alumina$가 많이 생성되었지만 시간이 갈수록 ${\gamma}-Alumina$의 양에는 변화 없이 ${\alpha}-alumina$가 많이 생겨남을 알 수 있었다. 이런 결과는 micro plasma에 의해서 ${\gamma}-Alumina$가 우선 생성되고, 이후 계속되는 micro plasma의 열에 의해서 ${\alpha}-alumina$로의 전이가 일어나기 때문으로 판단된다.

• 공업화학
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• 제3권3호
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• pp.527-534
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• 1992

Raney nickel 촉매를 이용하여 알칼리형 연료전지의 수소극을 제작하였다. $700^{\circ}C$에서 소결한 Raney nickel로 제작한 수소극의 경우 가장 좋은 전극성능을 갖는 $450mA/cm^2$의 전류밀도를 나타냈으며 이때의 평균촉매입자 크기는 $90{\AA}$이었다. CO-chemisorption 측정 및 분극곡선과 Tafel slope를 통하여 PTFE의 첨가량에 대한 전극의 전기화학적 성능을 고찰하였다. CO-chemisorption 측정 결과 5wt%의 PTFE가 첨가되었을 때 최고값을 갖는 것이 확인되었으나 전극에서의 전류밀도와 Tafel slope를 비교한 결과 10wt%의 PTFE를 첨가하는 경우가 가장 적당함을 알았다. Raney nickel제조시 nicke과 aluminum의 함량비는 60:40의 경우에 가장 좋은 전극 특성을 나타내었으며 담지량은 $0.25g/cm^2$의 경우가 적당하였다. 전극제조시 촉매층의 press압 및 촉매층과 기체확산층과의 접합시의 Press압에 대한 영향도 검토하였다. 또한 촉매의 표면 구조를 SEM으로 관찰하였으며 활성화시간 및 열처리 온도 등 여러가지 조건에 대한 전극의 영향도 고찰하였다.