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박희구,백승욱 啓明大學校 産業技術硏究所 1998 産業技術硏究所 論文報告集 Vol.21 No.2
Thin film of amorphous V₂O5 was sputtered on a quartz crystal with a vanadium target in Ar-O₂atmosphere and characterized employing QCM, impedance analyzer, and linear cycle voltammetry(lcv). Simultaneous QCM and lcv measurements showed that Li ion intercalation into the a-V₂O5 involved one lithium iron for each electron up to Li compositions of 0.7. There was no evidence of incorporation of solvent. However, at higher compositions(x>0.7), there was significant departure of the measured mass from the theoretically calculated one. Stress effect apparently caused the deviation during Li intercalation into the a-V₂O5. Impedance analysis revealed that as more Li is inserted, the charge transfer resistance increased as well and effective diffusion coefficient decreased from 8.5 x 10-(11)㎠/s to 1.9 x 10(-11)㎠/s.
Transpeptidase 억제제로서의 dithiocarbazate 유도체의 설계와 합성연구
박희구,백승욱 啓明大學校 産業技術硏究所 1998 産業技術硏究所 論文報告集 Vol.21 No.2
Dithiocarbazate analogs of acyl-D-Ala-D-Ala bearing thiocarbazate moiety in the place of the C-terminal peptide unit have been designed as a potential irreversible inhibitor of D-alanyl-D-alanyl transpeptidases. The dithiocarbazate derivatives were readily synthesized by the treatment of acylhydrazide with carbon disulfide in ethanolic KOH solution, followed by the addition of 2-bromopropionic acid. The dithiocarbazate analog of acyl-D-Ala-D-Ala bearing a proton on the nitrogen atom afforded a cyclic N-aminorhodanine upon acidification of the corresponding dithiocarbazate potassium salt. The synthesized carbazate 2a and 2b exhibited ca. 20% inhibition of transpetidases.
QCM and Electrochemical Studies of Li and Zn Intercalation in V6O13 ( NS )
Park, Heai Ku,Such, Soong Hyuck,Smyrl, W. H. 한국공업화학회 1995 Journal of Industrial and Engineering Chemistry Vol.1 No.1
Quartz crystal microbalance(QCM) and linear sweep voltammetry were empolyed to perform in situ mass and charge measurement on Li/V_6O_13(NS) and Zn/V_6O_13(NS) cells. At low Li and Zn compositions in V_6O_13, the simple metal ion intercalation/release process was observed. But at high Li and Zn compositions, secondary processes(morphology change and other complexities), in addition to simple metal ion insertion, were involved during intercalation process and morphology change occurred during deintercalation process. Early faradaic capacity loss of the cell was largely due to the secondary processes.
리튬이차전지용 AgxCuyV2O5 Xerogel의 전기화학적 특성
박희구 ( Heai Ku Park ),김용우 ( Yong Woo Kim ),이만호 ( Man Ho Lee ),백승욱 ( Seung Uk Paik ) 한국공업화학회 2003 공업화학 Vol.14 No.4
바나듐 산화물계 양극소재의 물성을 향상시키고자 졸겔법을 이용하여 제조한 V_2O_5 xerogel에 미량의 Ag와 Cu 원소를 도핑시켜 Ag_xCu_yV_2O_5 xnogel을 제조하여 리튬이차전지용 양극소재로서의 전기화학적 및 표면특성을 연구하였다. Ag_xCu_yV_2O_5 xnogel은 무정형의 층상 intercalation 소재로 표면구조는 섬유모양의 단위체가 서로 얽혀 일정한 방향으로 성장하여 비등방성 sheet를 형성하고 있다. 도핑되어진 Ag와 Cu의 양에 따른 전지용량 및 출력특성 등이 첨가량에 따라 변하였다. 전지의 평균용량은 적어도 120 mAh/g 이상이며 coulombic efficiency는 90% 이상으로 산화 ·환원과정이 가역적이며 사이클 특성이 우수하였다. In order to improve the properties of vanadium oxide as cathodes, Ag_xCu_yV_2O_5 gel was synthesized by deliberately adding a small amount of Ag and Cu to a V_2O_5 sol derived via sol-gel process. The electrochemical properties of a new mixed oxide Ag_xCu_yV_2O_5 xerogel as a Li intercalation compound have been investigated in the relation with structural characteristics. It appeared the amorphous layered material and entangled fibrous textures have been grown to form anisotropic corrugated fibrils. The specific capacity and rate characteristics were dependent upon the added amount of dopant, Cu and Ag. Average specific capacity of the Ag_xCu_yV_2O_5 xerogel was more than 120 mAh/g, and coulombic efficiency was at least ninety percent. The overall electrochemical properties, the reversibility and cell capacity, were enhanced compared to the undoped vanadium pentoxide.