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쌀밥으로 제조된 활성탄을 사용하는 전기이중층형 슈퍼커패시터 전극의 전기화학적 특성
조운,김용일,윤재국,유정준,윤하나,김성수,김종휘,Jo, Un,Kim, Yong-Il,Yoon, Jae-Kook,Yoo, Jung-Joon,Yoon, Ha-Na,Kim, Sung-Soo,Kim, Jong-Huy 한국전기화학회 2013 한국전기화학회지 Vol.16 No.3
쌀밥을 출발물질로 활용하고 수열합성법과 화학적 활성화를 위한 KOH용액 진공함침 등의 방법으로 제조된 활성탄의 전기이중층 초고용량 커패시터의 전극에 대한 전기화학적 전극특성을 확인 하였다. 제조된 활성탄의 물성을 SEM, EDS, XRD, TG, 비표면적, 기공크기 분포 등의 분석을 통해 조사하였다. 또한, 슈퍼커패시터의 전극에 대한 순환전류 측정과 교류 임피던스 측정 실험을 통해 전기화학적 특성을 확인하였다. 수열합성법을 통하여 직경 $5{\sim}7{\mu}m$ 인 구형의 탄소 입자를 얻었으며 활성화 온도 $800^{\circ}C$로 제조된 활성탄은 비표면적이 $1631.8cm^2/g$, 기공크기 분포가 0.9~2.1 nm에 집중적으로 분포하였으며, 마이크로 기공체적이 $0.6154cm^3/g$ 임을 알 수 있었다. 이 활성탄을 사용하여 제작된 전극은 6M KOH 전해액에서 비용량 236 F/g(@5 mV/s), 194 F/g(@100 mV/s), 137 F/g(@500 mV/s)의 우수한 특성을 나타내었다. 충방전 싸이클 수명시험 결과, 200 mV/s의 주사속도에서 100,000회 충방전 시험 후에도 초기용량 대비 91.2%의 용량을 유지함을 확인하였다. From the cooked-rice as a raw material, activated carbons throughout a hydrothermal synthesis and vacuum soak of KOH for chemical activation were obtained. Activated carbon electrodes for electric double layer supercapacitors were prepared and electrochemical characteristics were examined. Including the specific surface area by BET method and pore size distribution by NLDFT method, physical properties of activated carbons were investigated by means of SEM, EDS, XRD, and TG analyses. Cycle voltammetry and AC-impedance measurements were conducted to confirm the electrochemical characteristics for the electrodes. From hydrothermal synthesis, $5{\sim}7{\mu}m$ diameters of spherical carbons were obtained. After the activation at $800^{\circ}C$, it was notable for the activated carbon to be the specific surface $1631.8cm^2/g$, pore size distribution in 0.9~2.1 nm, and micro-pore volume $0.6154cm^3/g$. As electrochemical characteristics of the activated carbon electrode in 6M KOH electrolyte, it was confirmed that the specific capacitances of 236, 194, and 137 F/g at the scan rate of 5, 100, and 500 mV/s respectively were exhibited and 91.2% of initial capacitance after 100,000 cycles at 200 mV/s was maintained.
Poly(acrylonitrile) 부직포 분리막에 코팅된 하이드로겔 고분자 전해질을 포함하는 활성탄 수퍼커패시터 특성
모하메드라티파투 ( Mohammed Latifatu ),고장면 ( Jang Myoun Ko ),이영기 ( Young Gi Lee ),김광만 ( Kwang Man Kim ),조정대 ( Jeong Dai Jo ),장윤석 ( Yun Seok Jang ),유정준 ( Jung Joon Yoo ),김종휘 ( Jong Huy Kim ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.5
6M KOH 수계 전해액에 potassium poly(acrylate) (PAAK)를 3 wt% 포함시켜 제조한 하이드로겔을 poly(acrylonitrile)부직포 분리막에 코팅하고, 이를 활성탄 수퍼커패시터의 분리막 및 전해질로 사용하여 수퍼커패시터의 고율특성 향상을 시도하였다. 이 분리막 및 전해질은전자현미경 관찰 결과 PAAK 하이드로겔이 부직포의 표면기공에 균일하게 코팅되어 있으며, 24일 동안 하이드로겔의 합습도가 230% 이상으로 균일하게 유지되었고, 6 M KOH 전해액을 사용한 경우(3.6×10-2 S cm-1)보다 약간 낮은 2.9×10-2 S cm-1의 이온전도도를 나타내었다. 활성탄을 활물질로 사용한 대칭형 수퍼커패시터에 이 분리막 및 전해질을 채택한 경우 사이클릭볼타메트리 시험에서 1000 mV s-1의 고속스캔 조건에서도 27 F g-1 이상의 높은 비축전용량과 1000 사이클 경과후에도 97% 이상의 유지율을 나타내는데, 이는 부직포 상에 코팅된 PAAK 하이드로겔 전해질이 활성탄 전극과 부직포 분리막 사이에서 강력한 계면밀착을 유지할 수 있기 때문이다. A hydrogel electrolyte consisting of potassium poly(acrylate) (PAAK) (3 wt%) in 6 M KOH aqueous solution is coated on poly(acrylonitrile) nonwoven separator to examine high-rate characteristics of activated carbon supercapacitor adopting the separator. The hydrogel is homogeneously coated on the surface pores of the nonwoven separator. The electrolyte uptake of the PAAK hydrogel maintains for 24 days higher than 230% and the coated separator shows slightly lower ionic conductivity (2.9×10-2 S cm-1) than that (3.6×10-2 S cm-1) of using 6 M KOH only. The activated carbon supercapacitor adopting the coated separator shows a specific capacitance higher than 27 F g-1 at 1000 mV s-1 and a retention ratio higher than 97% after the 1000th cycle. This is due to strong interfacial contact of coated hydrogel electrolyte between the activated carbon electrode and the nonwoven separator.
이철호,박세영,이종균,임석원,김현식,이광렬,유정준 대한소화기내시경학회 1997 Clinical Endoscopy Vol.17 No.5
Background/Aims: Many endoscopists in Korea lack an understanding of laterally spreading, or creeping tumors(LSTs) which characteristically grow laterally, as opposed to other polypoid lesions, and which show superficially elevated lesions. An LST is similar in color to the adjacent normal mucosa, so it is difficult to recognize, but it can be detected by chromoscopy. When it grows to over 2-3 cm in its largest diameter, it can have malignant foci. It is important not to overlook the lesion and to remove it in a timely manner. Methods: The authors experienced 9 cases of LSTs from Jan. 1996 to Jan. 1997. We reviewed those 9 cases clinically, endoscopically, and pathologically, and tried to establish the diagnostic and therapeutic key points. Results: The most common age group was the fifth decade. The male-ta-female ratio was 5:4. Four cases were asymptomatic, and lower abdominal pain and rectal bleeding were seen in 2 cases respectively. The rectum and the sigmoid colon were the most commonly involved sites showing 88.9% (8/9). Granular-type(nodule-aggregating-type) LSTs were seen in 4 cases and nongranular types(non-nodule-aggregating types) in 5 cases. 66.7%(6/9) were larger than 2 cm in the largest diameter. A tubular adenoma was seen in each of 5 cases; among them, I case had cellular atypia and another case revealed a strbmucosal(sm) carcinoma. Two tubulovillous adenomas had intramucosal carcinomas. The lesions which contained malignancies were all larger than 2 cm in their largest diameter. Two granular types with large nodules had mucasal carcinomas. The sm carcinoma was a nongranular type. Endoscopically, redness was observed in 66.7%(6/9) of the cases and depression in 33.3%(3/9). The sm carcinorraa had both redness and depression. Three cases underwent endoscopic piecemeal mucosal resection(EPMR) and the other 3 cases underwent endoscopic mucosal resection (EMR). A low anterior resection was performed on one patient; there was no lymph node metastasis. Conclusions: The characteristics of LSTs are important in their diagnosis and management. Nongranular-type LSTs are not uncommon, despite the difficulty in recognizing them by endoscopy. Pathologically, LSTs, in general, are tubular or tubulovillous adenomas. When they are over 2 cm in their largest diameter, they are likely to have malignancies. Giant nodule, redness and depression are important feattues indicating malignancy, especially an sm earcinorna. An EPMR or an EMR is the main treatment option, but depending on the depth of invasion, surgical resection may need to be considered.
이철호,박세영,이종균,임석원,김현식,이광렬,유정준 대한소화기내시경학회 1997 Clinical Endoscopy Vol.17 No.4
Background: This study was undertaken to review cases of juvenile polyps with respect to clinical and endoscopic features. Methods: Of the 544 cases of colonoseopic polypectomies performed from Jan. 1 to Jan. 1997, 14 cases(2.6%) involved juvenile poiyps. Those 14 cases were analyzed with special consideration given to colonoscopic aspects. Results: The most common age groups were the fifth and the sixth decades, comprising 50%. There were two children below 10 years of age. Males were predominant in the ratio of 1.3:1. Rectal bleeding was the most common symptom, and 4 cases were asymptomatic. Mediumsized(6-10 mm) polyps were the most common, 7 eases(50%), and large($gt;1 cm) polyps were the next most common, 5 cases(35.7%). The first predilection of site was the rectum, 8 cases(57.1%); the second was the sigmoid colon with 5 cases(35.7%). Grossly, pedunculated polyps were the largest in number, accountieg for 64.3% of the cases; the others were all subpedunculated. In 9 cases(64.3%), the preoperative macroscopic diagnoses were consistent with the final diagnoses; in the other cases, the polyps were initially diagnosed as being adenomatous. Adenomatous and inflammatory polyps were associated with 3 cases, who were all men. White spots were noticed around the polyp base in 4 cases (28.6%); the clinical significance of those should be investigated further. All 14 patients underwent polypectomy by endoscopic snare resection without any complications. Conclusions: Colonoscopy should be the main tool for diagnosis and treatment of juvenile polyps. Juveoile polyps should be taken into account in cases of rectal bleeding and need to be differentiated from adenomatous polyps. Endoscopic polypectomy is an adequate procedure for the treatment of a solitary juvenile paiyp.