• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.289-289
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• 2007

Spinel structured $LiMn_2O_4$ is more economic and environmental friendly to be used as commercial active material for secondary battery compared to Co-oxide material active material, but spinel structure of $LiMn_2O_4$ is unstable and its capacitance decreases with increase of cycle. Therefore, the purpose of our sturdy is to improve the stability of $LiMn_2O_4$ spinel structure and increase its capacitance by using substituents or dopants. $LiMn_2O_4$ powder was synthesized by charging substituents or dopants mole fractions, and temperatures. Crystal state, structure and specific surface area of the synthesized powder were measured and also characteried electrochemically by measuring its impedance, charge-discharge capacitance and etc.

• 센서학회지
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• 제30권2호
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• pp.71-75
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• 2021

Recently, transition-metal-based hydroxide materials have attracted significant attention in various electrochemical applications owing to their low cost, high stability, and versatility in composition and morphology. Among these applications, transition-metal-based hydroxides have exhibited significant potential in supercapacitors owing to their multiple redox states that can considerably enhance the supercapacitance performance. In this study, nanostructured Ni-Mn double hydroxide is directly grown on a conductive substrate using an electrodeposition method. Ni-Mn double hydroxide exhibits excellent electrochemical charge-storage properties in a 1 M KOH electrolyte, such as a specific capacitance of 1364 Fg-1 at a current density of 1 mAcm-2 and a capacitance retention of 94% over 3000 charge-discharge cycles at a current density of 10 mAcm-2. The present work demonstrates a scalable, time-saving, and cost-effective approach for the preparation of Ni-Mn double hydroxide with potential application in high-charge-storage kinetics, which can also be extended for other transition-metal-based double hydroxides.

• 공업화학
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• 제24권2호
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• pp.201-207
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• 2013

본 연구에서는 전기이중층 커패시터의 전극 활물질로 사용되는 페놀계 활성탄소의 비 정전용량의 증가를 위하여 붕산을 이용하여 표면처리를 수행하였다. 또한, 붕산 처리가 전기화학 특성에 미치는 영향에 대하여 고찰하였다. 활성탄소의 붕산 처리는 활성탄소의 표면에 전기화학적 특성 향상에 도움이 되는 퀴논형 관능기(O=C)의 비율을 효과적으로 증가시켰으며, 비표면적과 총 기공 부피 및 미세공 부피를 증가시켰다. 최적의 조건으로 붕산 처리된 활성탄소는 미처리활성탄소에 비해 비 정전용량이 약 20% 증가하였다. 이러한 결과로부터 활성탄소의 붕산 처리는 활성탄소의 비 정전용량을 효과적으로 증가시킬 수 있다고 사료된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.683-686
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• 2004

In recent years, the supercapacitor and hybrid capacitor have related with substitutional energy source focused of many scientists because of their usage in power sources for electric vehicles, computers and other electric devices. The storage energy of electrical charge is based on electrostatic interactions in the electric double layer at the electrode/electrolyte interface, resulting in high rate capability and long cycle performance compared with batteries based on Faradaic electrode reactions. So we have been considered to carbon nanofibers as the ideal material for supercapacitors due to their high utilization of specific surface area, good conductivity, chemical stability and other advantages. In this work, we aimed to find out that the capacitance have increased because of electrochemical capacitance to provide by carbon nanofibers. Also carbon nanofibers based on chemical method and water treatment have been resulted larger capacitances and also exhibit better electrochemical behaviors about 15% than before of nontreated state. And also optical observations with treated and nontrteated carbon nanofibers discussed by the TEM, SEM, EDX, BET works and specific surface area analyzer. Their results also focused on the surface area of electrode and electrical capacitance was also improved by the effect of surface treatments.

• Korean Chemical Engineering Research
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• 제55권4호
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• pp.467-472
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• 2017

Poly(acrylonitrile) (PAN) 부직포 분리막 상에 poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA), potassium poly(acrylate) (PAAK)의 각 고분자와 6 M KOH로 조성된 전해질을 코팅하고 이를 활성탄 수퍼커패시터에 적용하여 고분자 종류에 따른 전기화학적 특성을 조사하였다. 특징적으로 PEO와 PVA는 그 고분자 사슬의 자체 구조로 인해 알칼리 전해액 성분 (KOH)과의 상호작용이 활성적이지 않은데 반하여, PAAK는 3 wt% 함량만으로도 주사슬 및 곁사슬에 분포하는 $COO^-K^+$ 이온쌍과 전해액 내 해리되어 있는 $K^+$ 및 $OH^-$ 이온들과의 상호작용이 활성적으로 진행되어 하이드로겔을 형성하며, 이것이 이온전도 및 수퍼커패시터의 전기화학적 특성에 큰 영향을 주었다. 결과적으로 PAAK-KOH 전해질/PAN 분리막으로 포함한 활성탄 수퍼커패시터가 가장 우수한 축전용량 ($100mVs^{-1}$에서 $46.8Fg^{-1}$)을 나타내었다.

• 전기화학회지
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• 제25권1호
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• pp.22-31
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• 2022

Carbon nanomaterials are considered to be the materials of choice for the fabrication of electrochemical energy storage devices due to their stability, cost-effectiveness, well-established processing techniques, and superior performance compared to other active materials. In the present work, reduced graphene oxide (rGO) has been synthesized and used for the fabrication of a symmetric supercapacitor. The electrochemical performance of the fabricated supercapacitors with three different aqueous electrolytes namely 0.5 M H₂SO₄, 0.5 M H₃PO₄, and 1.0M Na₂SO₄ have been compared and analyzed. Among the three electrolytes, the highest areal specific capacitance of 14 mF/cm² was calculated at a scan rate of 5 mV/s observed with 0.5M H₃PO₄ electrolyte. The results were also confirmed from the charge/discharge results where the supercapacitor with 0.5M H₃PO₄ electrolyte delivered a specific capacitance of 11 mF/cm² at a current density of 0.16 mA/cm². In order to assess the stability of the supercapacitor with different electrolytes, the cells were subjected to continuous charge/discharge cycling and it was observed that acidic electrolytes showed excellent cyclic stability with no appreciable drop in specific capacitance as compared to the neutral electrolyte.

• 한국진공학회지
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• 제10권4호
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• pp.440-448
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• 2001

논문에서는 원통형 및 평판형 반응기에 20 kV의 사각파형 펄스전원을 인가하여 대기압 절연막 방전 플라즈마 반응기의 동작특성을 관찰하였다. 전류-전압파형과 하전량-전압곡선을 관찰한 결과 반응기의 정전용량 크기에 따라서 최적의 운전효율을 갖는 최적운전주파수 $f_0$가 $f_0\proptoexp(-C)$의 관계를 갖고 있음을 알았다. 이 관계를 이용하여 반응기에서 소실되는 소모전력을 구하였다. 반응기의 소모전력은 반응기의 구조와 전극의 유전물질의 종류 등의 함수인 반응기 정전용량 값에 따라서 변화하였으며 반응기의 특정한 정전용량 값에서 최대값을 가졌다. 이 정전용량 값을 이용하여 최적효율을 갖는 DBD 반응기를 설계할 수 있을 것으로 사료된다.

• 한국재료학회지
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• 제17권2호
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• pp.81-85
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• 2007

Embedded capacitor technology can improve electrical perfomance and reduce assembly cost compared with traditional discrete capacitor technology. To improve the capacitance density of the $Al_2O_3$ based embedded capacitor on Cu cladded fiber reinforced plastics (FR-4), the specific surface area of the $Al_2O_3$ thin films was enlarged and their surface morphologies were controlled by anodization process parameters. From I-V characteristics, it was found that breakdown voltage and leakage current were 23 V and $1{\times}10^{-6}A/cm^2$ at 3.3 V, respectively. We have also measured C-V characteristics of $Pt/Al_2O_3/Al/Ti$ structure on CU/FR4. The capacitance density was $300nF/cm^2$ and the dielectric loss was 0.04. This nano-porous $Al_2O_3$ is a good material candidate for the embedded capacitor application for electronic products.

• Korean Chemical Engineering Research
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• 제43권3호
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• pp.425-431
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• 2005

비표면적이 큰 혼합 활성탄과 전도도가 높은 전도성고분자 폴리피롤을 이용하여 낮은 임피던스와 높은 에너지밀도를 가지는 새로운 형태의 슈퍼커패시터를 제조하였다. 전극 활성물질로 활성탄 BP-20과 MSP-20을 사용하였고, 전기 전도도를 높이기 위하여 활성탄에 전도성 개량제 카본블랙(Super P)과 2-naphthalenesulfonic acid(2-NSA)로 도핑된 전도성 고분자 폴리피롤을 첨가하였다. 용액상태의 유기 결합제 poly(vinylidenefluoride-co-hexafluoropropylene) [P(VdF-co-HFP)/NMP]에 전극 소재들을 혼합시켜 전극을 제조하였다. 실험 결과 최적의 전극 배합비는 78(MSP-20: BP-20=1 : 1) : 17 (Super P : Ppy=10:7) : 5 [P(VdF-co-HFP)] wt％이었다. 폴리피롤이 7 wt％ 첨가된 단위셀의 비정전용량은 28.02 F/g, DC-ESR은 $1.34{\Omega}$, AC-ESR은 $0.36{\Omega}$, 에너지밀도는 19.87 Wh/kg, 동력밀도는 9.77 kW/kg이었다. 500회 충 방전 실험 후 초기 정전용량의 80％를 유지하여 사이클 특성이 우수하였다. 폴리피롤을 첨가함으로써 낮은 내부 저항, 슈도용량(pseudo capacitance)의 발현, 낮은 전하전이저항 및 빠른 반응속도에 의하여 급속한 충 방전이 가능하였다. 그리고 활성탄의 흡탈착에 의한 비패러데이 용량과 폴리피롤의 산화 환원에 의한 슈도용량의 복합현상 때문에 비정전용량이 높게 나타났다.

• Korean Journal of Acupuncture
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• 제26권4호
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• pp.1-11
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• 2009

Objectives : The object of this study is measuring energy (skin capacitance) distribution on the specific acupionts and analyzing change patterns of meridian energy according to time or synchronous time. Methods : To check energy distribution using the meridian energy measurement system(DMM-1000), ten specific acupoints(ST34, ST36, ST40, ST41, ST42, ST43, ST44, ST45, BL21, CV12) were chosen. We checked the energy distribution and analyzed the change patterns before and after meal. We checked the state of the energy of ST meridian which is considered to have relation to stomach organ activity. Based on the hypothesis regarding energy difference due to Qi flowing, we compared energy potential on 10 specific acupoints. Results and Conclusions : Electric energy of each specific acupoint was different according to subjects and time. Through this study, we proposed an indispensable condition of energy difference due to Qi flowing through meridian.