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화학적 기상 응축(CVC)법을 이용한 철-몰리브덴합금 나노 입자와 와이어의 제조
하종근,조권구,김기원,류광선,Ha, Jong-Keun,Cho, Kwon-Koo,Kim, Ki-Won,Ryu, Kwang-Sun 한국분말야금학회 2010 한국분말재료학회지 (KPMI) Vol.17 No.3
Iron(Fe)-Molybdenum(Mo) alloyed nanoparticles and nanowires were produced by the chemical vapor condensation(CVC) process using the pyrolysis of iron pentacarbonyl($Fe(CO)_5$) and Molybdenum hexacarbonyl($Mo(CO)_6$). The influence of CVC parameter on the formation of nanoparticle, nanowire and size control was studied. The size of Fe-Mo alloyed nanoparticles can be controlled by quantity of gas flow. Also, Fe-Mo alloyed nanowires were produced by control of the work chamber pressure. Moreover, we investigated close correlation of size and morphology of Fe-Mo nanoparticles and nanowires with atomic quantity of inflow precursor into the electric furnace as the quantitative analysis. Obtained nanoparticles and nanowires were investigated by field emission scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction.
양극산화알루미늄의 형상제어와 이를 이용한 실리콘 분말 전극 지지체 효과
송주석,하종근,김유영,박동규,안인섭,안주현,조권구,Song, Ju-Seok,Ha, Jong-Keun,Kim, Yoo-Young,Park, Dong-Kyu,Ahn, In-Shup,Ahn, Jou-Hyeon,Cho, Kwon-Koo 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.4
Anodic aluminum oxide (AAO) has been widely used for the development and fabrication of nano-powder with various morphologies such as particle, wire, rod, and tube. So far, many researchers have reported about shape control and fabrication of AAO films. However, they have reported on the shape control with different diameter and length of anodic aluminum oxide mainly. We present a combined mild-hard (or hard-mild) anodization to prepare shape-controlled AAO films. Two main parameters which are combination mild-hard (or hard-mild) anodization and run-time of voltage control are applied in this work. The voltages of mild and hard anodization are respectively 40 and 80 V. Anodization was conducted on the aluminum sheet in 0.3 mole oxalic acid at $4^{\circ}C$. AAO films with morphologies of varying interpore distance, branch-shaped pore, diameter-modulated pore and long funnel-shaped pore were fabricated. Those shapes will be able to apply to fabricate novel nano-materials with potential application which is especially a support to prevent volume expansion of inserted active materials, such as metal silicon or tin powder, in lithium ion battery. The silicon powder electrode using an AAO as a support shows outstanding cycle performance as 1003 mAh/g up to 200 cycles.
김유영,하종근,조권구,Kim, Yoo-Young,Ha, Jong-Keun,Cho, Kwon-Koo 한국분말재료학회 (*구 분말야금학회) 2019 한국분말재료학회지 (KPMI) Vol.26 No.1
Layered $LiNi_{0.83}Co_{0.11}Mn_{0.06}O_2$ cathode materials single- and dual-doped by the rare-earth elements Ce and Nd are successfully fabricated by using a coprecipitation-assisted solid-phase method. For comparison purposes, non-doping pristine $LiNi_{0.83}Co_{0.11}Mn_{0.06}O_2$ cathode material is also prepared using the same method. The crystal structure, morphology, and electrochemical performances are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping, and electrochemical techniques. The XRD data demonstrates that all prepared samples maintain a typical ${\alpha}-NaFeO_2$-layered structure with the R-3m space group, and that the doped samples with Ce and/or Nd have lower cation mixing than that of pristine samples without doping. The results of SEM and EDS show that doped elements are uniformly distributed in all samples. The electrochemical performances of all doped samples are better than those of pristine samples without doping. In addition, the Ce/Nd dual-doped cathode material shows the best cycling performance and the least capacity loss. At a 10 C-rate, the electrodes of Ce/Nd dual-doped cathode material exhibit good capacity retention of 72.7, 58.5, and 45.2% after 100, 200, and 300 cycles, respectively, compared to those of pristine samples without doping (24.4, 11.1, and 8.0%).
폐 리튬 이차전지로부터 회수된 황산코발트 제조 및 이를 이용해 합성된 산화리튬코발트 양극활물질의 전기화학적 특성
김미소,하종근,박세빈,안주현,최임식,조권구,Kim, Mi-So,Ha, Jong-Keun,Park, Se-Bin,Ahn, Jou-Hyeon,Choi, Im-Sic,Cho, Kwon-Koo 한국전기화학회 2014 한국전기화학회지 Vol.17 No.2
본 연구에서는 폐 리튬이차전지의 스크랩으로부터 순도 높은 황산코발트($CoSO_4$) 용액을 회수하고, 회수된 용액을 이용하여 리튬이차전지의 양극활물질인 $LiCoO_2$를 제조하여 전기화학적 특성을 평가하였다. 황산코발트의 제조는 황산과 과산화수소수를 이용하여 원료물질로부터 금속물질을 녹여내기 위한 침출단계, 가성소다를 이용한 pH 조절로 1차 불순물을 제거하기 위한 중화공정 및 D2EHPA와 $CYANEX^{(R)}272$를 이용하여 2차 불순물을 제거하기 위한 용매추출공정을 거쳐 고순도의 용액을 회수한다. 회수된 황산코발트는 증류수와 희석하여 6 wt.% 황산코발트 용액으로 만들고, 다시 옥살산과 혼합 및 교반 후 건조, 하소 및 리튬의 원료가 되는 $Li_2CO_3$ 분말과 혼합 후 합성 공정을 거쳐 이차전지의 양극활물질인 $LiCoO_2$를 제조하였다. 이를 이용하여 전극을 조립하고, 전기화학적 특성을 평가하였다. 전기화학적 특성은 본 실험에서 합성된 $LiCoO_2$와 상업용 $LiCoO_2$(Aldrich사)를 비교하였으며, 결과는 유사하거나 혹은 합성된 $LiCoO_2$가 더 우수한 것을 확인할 수 있었다. 따라서, 본 실험을 통해 양극활물질의 재활용 가능성을 확인하였다. The electrochemical properties using the cells assembled with the synthesized $LiCoO_2$(LCO) were evaluated in this study. The LCO was synthesized from high-purity cobalt sulfate($CoSO_4$) which is recovered from the cathode scrap in the wastes lithium ion secondary battery(LIB). The leaching process for dissolving the metallic elements from the LCO scrap was controlled by the quantities of the sulfuric acid and hydrogen peroxide. The metal precipitation to remove the impurities was controlled by the pH value using the caustic soda. And also, D2EHPA and $CYANEX^{(R)}272$ were used in the solvent extraction process in order to remove the impurities again. The high-purity $CoSO_4$ solution was recovered by the processes mentioned above. We made the 6 wt.% $CoSO_4$ solution mixed with distilled water. And the 6 wt.% $CoSO_4$ solution was mixed with oxalic acid by the stirring method and dried in oven. $LiCoO_2$ as a cathode material for LIB was formed by the calcination after the drying and synthesis with the $Li_2CO_3$ powder. We assembled the cells using the $LiCoO_2$ powders and evaluated the electrochemical properties. And then, we confirmed possibility of the recyclability about the cathode materials for LIBs.
안성수(Ahn Sung Soo),하종근(Ha Jong Keun) 한국도시행정학회 2006 도시 행정 학보 Vol.19 No.1
The purpose of the study is to analyze operation realities of resident autonomy centers in Changwon-city. The study conducted literature review research methods based on operation reality data of resident autonomy centers. In addition, the study adopted survey research methods intented for the members of resident autonomy committee, center using residents, and the officials in charge. The results of the research are the followings. At first, the members of resident autonomy committee highly consisted of self-management businessmen and housewives. Secondly, the operation programs of resident autonomy centers leaned to cultural leisure functions and citizen education functions. Thirdly, volunteers of low level municipal offices, such as, Eup, Myon, and Dong, have hardly participated in the operation programs. Instead of them, they have mostly participated in the operation support. Lastly, the educations for the members of resident autonomy committee and the officials in charge were not executed good enough. The research groped incremental and substantial operation schemes to strengthen the original role of resident autonomy centers based on like these reality analyses and questionnaire survey results. Especially, the study emphasized preparation to turn a combination type operation system between citizen and officials endowing a project plan and an implementation authority of resident autonomy centers maintaining the present Eup, Myon, and Dong. In addition to that, the research presents a resident autonomy function reinforcement, a composition and operation of efficient and effective resident autonomy committees, and construction schemes of a volunteer manpower bank.
금속분말사출성형법으로 제조 된 WC-10Co계 초경합금 시편의 소결분위기에 따른 특성변화
강상대(Kang Sang Dae),김진화(Kim Jin Hwa),하종근(Ha Jong Keun),권영삼(Kwon Young Sam),조권구(Cho Kwon Koo),안인섭(Ahn In Shup) 한국생산제조학회 2011 한국생산제조시스템학회 학술발표대회 논문집 Vol.2011 No.4
This study was investigated for microstructure and mechanical properties of WC-10wt%Co insert tool alloy fabricated by PIM process. The WC-10wt%Co feedstock mixed with wax binder was fabricated by two blade mixer. After WC-10wt%Co feedstocks were injection molded, debinding process was carried by two-steps methods with solvent extraction and thermal debinding. The binder was eliminated with normal hexane for 24hours at 60℃ by solvent extraction, and subsequently thermal debinding was examined at the temperature 260℃ and 480℃ for 6 hours in H2/N2 mixed gas atmosphere.