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박경수,강이승,이찬기,홍현선,심종길,박정진,Park, Kyung-Soo,Swain, Basudev,Kang, Lee Seung,Lee, Chan Gi,Hong, Hyun Seon,Shim, Jong-Gil,Park, Jeung-Jin 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.3
Leaching of MOCVD dust in the LED industry is an essential stage for hydro-metallurgical recovery of pure Ga and In. To recover Ga and In, the leaching behavior of MOCVD scrap of an LED, which contains significant amounts of Ga, In, Al and Fe in various phases, has been investigated. The leaching process must be performed effectively to maximize recovery of Ga and In metals using the most efficient lixiviant. Crystalline structure and metallic composition of the raw MOCVD dust were analyzed prior to digestion. Subsequently, various mineral acids were tested to comprehensively study and optimize the leaching parameters such as acidity, pulp density, temperature and time. The most effective leaching of Ga and In was observed for a boiling 4 M HCl solution vigorously stirred at 400 rpm. Phase transformation of GaN into gallium oxide by heat treatment also improved the leaching efficiency of Ga. Subsequently high purity Ga and In can be recovered by series of hydro processes.
비정질 실리콘 산화물을 이용한 리튬망간실리콘산화물의 합성 및 전기화학적 특성 평가
진연호,이근재,강이승,정항철,홍현선,Jin, Yun-Ho,Lee, Kun-Jae,Kang, Lee-Seung,Jung, Hang-Chul,Hong, Hyun-Seon 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.3
Mass production-capable $Li_2MnSiO_4$ powder was synthesized for use as cathode material in state-of-the-art lithium-ion batteries. These batteries are main powder sources for high tech-end digital electronic equipments and electric vehicles in the near future and they must possess high specific capacity and durable charge-discharge characteristics. Amorphous silicone was quite superior to crystalline one as starting material to fabricate silicone oxide with high reactivity between precursors of sol-gel type reaction intermediates. The amorphous silicone starting material also has beneficial effect of efficiently controlling secondary phases, most notably $Li_xSiO_x$. Lastly, carbon was coated on $Li_2MnSiO_4$ powders by using sucrose to afford some improved electrical conductivity. The carbon-coated $Li_2MnSiO_4$ cathode material was further characterized using SEM, XRD, and galvanostatic charge/discharge test method for morphological and electrochemical examinations. Coin cell was subject to 1.5-4.8 V at C/20, where 74 mAh/g was observed during primary discharge cycle.
조합 합성 시스템의 미세유체반응기를 이용한 CdSe 양자점 합성 및 분석
홍명환,이덕희,강이승,이찬기,김범성,김남훈,Hong, Myung Hwan,Lee, Duk-Hee,Kang, Lee-Seung,Lee, Chan Gi,Kim, Bum-Sung,Kim, Nam-Hoon 한국분말야금학회 2016 한국분말재료학회지 (KPMI) Vol.23 No.2
A microfluidic reactor with computer-controlled programmable isocratic pumps and online detectors is employed as a combinatorial synthesis system to synthesize and analyze materials for fabricating CdSe quantum dots for various applications. Four reaction condition parameters, namely, the reaction temperature, reaction time, Cd/Se compositional ratio, and precursor concentration, are combined in synthesis condition sets, and the size of the synthesized CdSe quantum dots is determined for each condition. The average time corresponding to each reaction condition for obtaining the ultraviolet-visible absorbance and photoluminescence spectra is approximately 10 min. Using the data from the combinatorial synthesis system, the effects of the reaction conditions on the synthesized CdSe quantum dots are determined. Further, the data is used to determine the relationships between the reaction conditions and the CdSe particle size. This method should aid in determining and selecting the optimal conditions for synthesizing nanoparticles for diverse applications.
미세유체반응기를 이용한 core/shell 연속 합성 시스템을 이용한 CdSe/ZnS 양자점 합성 및 분석
홍명환,주소영,강이승,이찬기,Hong, Myung Hwan,Joo, So Young,Kang, Lee-Seung,Lee, Chan Gi 한국분말야금학회 2018 한국분말재료학회지 (KPMI) Vol.25 No.2
Core/shell CdSe/ZnS quantum dots (QDs) are synthesized by a microfluidic reactor-assisted continuous reactor system. Photoluminescence and absorbance of synthesized CdSe/ZnS core/shell QDs are investigated by fluorescence spectrophotometry and online UV-Vis spectrometry. Three reaction conditions, namely; the shell coating reaction temperature, the shell coating reaction time, and the ZnS/CdSe precursor volume ratio, are combined in the synthesis process. The quantum yield of the synthesized CdSe QDs is determined for each condition. CdSe/ZnS QDs with a higher quantum yield are obtained compared to the discontinuous microfluidic reactor synthesis system. The maximum quantum efficiency is 98.3% when the reaction temperature, reaction time, and ZnS/CdSe ratio are $270^{\circ}C$, 10 s, and 0.05, respectively. Obtained results indicate that a continuous synthesis of the Core/shell CdSe/ZnS QDs with a high quantum efficiency could be achieved by isolating the reaction from the external environment.
LCD TV 해체 시 발생하는 PCB의 효율적 재활용을 위한 구조 분석 및 등급별 분류
홍명환,박경수,강이승,석한길,홍현선,Hong, Myung Hwan,Park, Kyung-Soo,Swain, Basudev,Kang, Lee-Seung,Suk, Han Gil,Hong, Hyun Seon 한국자원리싸이클링학회 2015 資源 리싸이클링 Vol.24 No.1
재활용을 위한 LCD TV 분해 시 영상 신호 송신, 전원 공급, 화상 구현 등을 위한 다양한 종류의 PCB가 발생한다. PCB에는 금이나 구리와 같은 유가금속이 다량 함유 되어 있으나 사용용도, PCB 패키징 방법에 따라 함유 되어 있는 유가금속의 종류와 함유량에 차이가 있다. 본 연구에서는 PCB 종류에 따른 구조 분석을 통하여 PCB에 함유 된 금과 구리의 함유량에 따라 PCB를 등급별로 분류 하고자 하였으며 금 회수 효율이 높은 PCB, 금 회수 효율이 낮은 PCB, 금이 함유되어 있지 않은 PCB 세 종류로 분류를 하였다. 또한 실제 LCD TV를 분해하여 발생된 PCB에 대한 함유량 분석을 통하여 PCB 내 금과 구리 함유량을 분석하였다. Various waste PCBs arose during disassembly of LCD TVs and monitors in which they originally functioned for transmission of imaging signal, power supply, and imaging control. In those functional PCBs, gold and copper are contained at far more acceptable level, exceeding mining grade ores. Those valuable metals and their contents widely vary with functionality and end use of PCBs. Therefore, compositional analysis of individual waste PCBs from disassembled LCD TVs and monitors were performed in the present study to classify them into three categories: high gold yield and low gold yield PCBs and those without gold contents. Besides, additional chemical analysis was made to reveal gold and copper contents in the waste PCBs arising from actual disassembly/separation of end-of-life LCD TVs and monitors.
홍현선,고영대,강이승,김건홍,정항철,Hong, Hyun-Seon,Ko, Young-Dae,Kang, Lee-Seung,Kim, Geon-Hong,Jung, Hang-Chul 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.3
Spherical nanosized cobalt powder with an average size of 150-400 nm was successfully prepared at room temperature from cobalt sulfate heptahydrate ($CoSO_4{\cdot}7H_2O$). Wet chemical reduction method was adopted to synthesize nano cobalt powder and hypophosphorous acid ($H_3PO_2$) was used as reduction agent. Both the HCP and the FCC Co phase were developed while $CoSO_4{\cdot}7H_2O$ concentration ranged from 0.7 M to 1.1 M. Secondary phase such as $Co(OH)_2$ and $CO_3O_4$ were also observed. Peaks for the crystalline Co phase having HCP and FCC structure crystallized as increasing the concentration of $H_3PO_2$, indicating that the amount of reduction agent was enough to reduce $Co(OH)_2$. Consequently, a homogeneous Co phase could be developed without second phase when the $H_3PO_2/CoSO_4{\cdot}7H_2O$ ratio exceeded 7.
홍현선,정항철,김건홍,강이승,석한길,Hong, Hyun-Seon,Jung, Hang-Chul,Kim, Geon-Hong,Kang, Lee-Seung,Suk, Han-Gil 한국분말야금학회 2013 한국분말재료학회지 (KPMI) Vol.20 No.3
Nano-sized cobalt powder was fabricated by wet chemical reduction method at room temperature. The effects of various experimental variables on the overall properties of fabricated nano-sized cobalt powders have been investigated in detail, and amount of NaOH and reducing agent and dropping speed of reducing agent have been properly selected as experimental variables in the present research. Minitab program which could find optimized conditions was adopted as a statistic analysis. 3D Scatter-Plot and DOE (Design of Experiments) conditions for synthesis of nano-sized cobalt powder were well developed using Box-Behnken DOE method. Based on the results of the DOE process, reproducibility test were performed for nano-sized cobalt powder. Spherical nano-sized cobalt powders with an average size of 70-100 nm were successfully developed and crystalline peaks for the HCP and FCC structure were observed without second phase such as $Co(OH)_2$.
LED 공정스크랩으로부터 Ga 회수를 위한 침출 거동 연구
박경수 ( Kyung Soo Park ),( Basudev Swain ),강이승 ( Lee Seung Kang ),이찬기 ( Chan Gi Lee ),엄성현 ( Sung Hyun Uhm ),홍현선 ( Hyun Seon Hong ),심종길 ( Jong Gil Shim ),박정진 ( Jeoung Jin Park ) 한국공업화학회 2014 공업화학 Vol.25 No.4
LED scraps consisting of highly crystalline GaN and their leaching behavior are comprehensively investigated for hydro-metallurgicalrecovery of rare metals. Highly stable GaN renders the leaching of the LED scraps extremely difficult in ordinaryacidic and basic media. More favorable state can be obtained by way of high temperature solid-gas reaction of GaN-Na2CO3powder mixture, ball-milled thoroughly at room temperature and subsequently oxidized under ambient air environment at1000-1200 ℃ in a horizontal tube furnace, where GaN was effectively oxidized into gallium oxides. Stoichiometry analysisreveals that GaN is completely transformed into gallium oxides with Ga contents of ~73 wt%. Accordingly, the oxidized powdercan be suitably leached to ~96% efficiency in a boiling 4 M HCl solution, experimentally confirming the feasibility ofGa recycling system development.