보고서 정보
주관연구기관 |
금오공과대학교 Kumoh National Institute of Technology |
연구책임자 |
이철경
|
참여연구자 |
조경식
,
백훈기
,
박제식
,
이재오
,
박광원
|
보고서유형 | 최종보고서 |
발행국가 | 대한민국 |
언어 |
한국어
|
발행년월 | 2014-04 |
주관부처 |
환경부 Ministry of Environment |
등록번호 |
TRKO201800001762 |
DB 구축일자 |
2018-12-15
|
키워드 |
고활성금속.경량금속.귀금속.금속회수.비수계 용매.친환경 전해.Reactive metals.Light metals.Precious metals.Metal recovery.Non-aqueous solvent.Eco-friendly electrolysis.
|
초록
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□ 개발 목적 및 필요성
○ 폐리튬전지, IT폐기물, 태양전지 스크랩으로부터 재활용 핵심기술인 고활성/경량/귀금속의 효과적인 회수를 위하여 비수계 그린 기반의 전해질 및 환경친화적인 차세대 전해법을 개발하고자 함
○ 환경친화적인 전해공정이라 함은 조업온도를 낮추고, 에너지 효율을 높이는 한편 환경에 영향을 주는 물질을 배제하는 공정이라 정의할 수 있으며, 비수계 용매를 활용한 전해가 이를 가능하게 할 수 있을 것으로 예상되며, 고활성/경량/귀금속을 함유하는 폐자원의 재활용에 모두 적용가능하며, 직접 회수가 불가능하였던 실
□ 개발 목적 및 필요성
○ 폐리튬전지, IT폐기물, 태양전지 스크랩으로부터 재활용 핵심기술인 고활성/경량/귀금속의 효과적인 회수를 위하여 비수계 그린 기반의 전해질 및 환경친화적인 차세대 전해법을 개발하고자 함
○ 환경친화적인 전해공정이라 함은 조업온도를 낮추고, 에너지 효율을 높이는 한편 환경에 영향을 주는 물질을 배제하는 공정이라 정의할 수 있으며, 비수계 용매를 활용한 전해가 이를 가능하게 할 수 있을 것으로 예상되며, 고활성/경량/귀금속을 함유하는 폐자원의 재활용에 모두 적용가능하며, 직접 회수가 불가능하였던 실리콘 등과 같은 금속들도 직접 회수할 수 있는 응용가능성이 매우 큰 기술임
○ 이를 통하여 기존의 수용액계 전해액으로 회수 불가능하였던 기술적 한계를 극복하고 새로운 차세대 전해회수 기술을 선점하여 폐자원 내 고활성 금속 회수 기술 분야에서 세계적 기술 선도를 이루고자 함
□ 연구개발 결과
○ 리튬, 마그네슘과 같은 경량 금속들은 IT산업, 자동차 산업에 없어서는 안 될 필수 금속소재들이고 첨단산업들의 빠른 성장으로 수반되는 경 량합금 원료소재의 수요도 국가적으로 중요한 이슈이다. 경량 금속들을 포함한 대부분의 희유금속들은 앞서 언급한 바와 같이 대부분 고온 건식법으로 용융시킨 후 분리, 회수하거나 특정 염으로 먼저 형성시킨 후 별도의 정제 및 환원제를 통한 금속 환원으로 회수된다. 이러한 기존 제련공정은 높은 작동 온도를 필요로 하는 대규모의 융융 및 환원로 필요, 높은 공정비용, 낮은 에너지 사용 효율, 그리고 환경오염을 일으키는 부산물 등의 문제점을 여전히 가지고 있다. 비수계 전해질을 사용한 상온 전해를 통하여 친환경적이면서 에너지 소비를 최소화하는 전해기술을 개발하였으며, 이를 리틈, 마그네슘의 일차 전해 그리고 리튬, 마그네슘을 함유하는 폐자원의 재활용에 응용이 가능함을 확인함.
○ 타이타늄과 같은 고활성 금속의 제련은 Kroll process, 반도체 재료인 실리콘의 제련은 Siemens 혹은 DuPont process에 의하여 이루어지는데 높은 조업온도(950~1,150 ℃), 장시간 회분식 공정, 에너지 고소비형 및 환경오염 물질(TiCl4, SiCl4, COx, Cl2 등)이 대량으로 발생하는 등 많은 개선점을 가진 공정이라 할 수 있다. 대안으로 개발된 Cambridge 대학에서 제안한 FCC process의 경우 TiO2를 원료로 하고 Ca을 Mg 대신에 환원제로 사용하며 CaO를 같은 반응기에서 재생하는 개선된 공정이지만 조업온도가 900 ℃로 여전히 높고, COx의 배출량이 매우 커서 기술적 진보가 큰 기술이라 할 수 없음
○ 비수계 전해질을 사용한 상온 전해를 통하여 친환경적이면서 에너지 소비를 최소화하는 전해기술을 개발하였고 이를 타이타늄, 네오디뮴 및 실리콘의 전해에 적용 가능하였음.
○ 귀금속 회수에 사용되는 유독 물질이나 소비 에너지를 크게 줄일 수 있는, 그리고 환경오염 물질을 배출하지 않는 친환경 공정을 구현하고 자 하였으며, 비수계 용매 기반의 백금족 금속의 분리공정 및 선택적 전해 기술을 개발하였음. 또한 맥동전해의 의하여 좁은 입도분포를 갖은 나노 크기의 팔라듐 합성이 가능하였으며, 순간적으로 고전압/고전류 인가가 가능하기 때문에 반응시간이 수초로 매우 짧으면서 수소와 같은 불순물의 혼입에 의한 오염이 존재하지 않았음.
○ 개발한 전해 회수 기술은 향후 막대한 소비량이 예상되는 이차전지, 전자-IT 산업폐자원 및 태양전지 스크랩 등을 주요 대상으로 하고 있음. 관련 폐자원으로부터 10종의 고활성/경량/귀금속(리튬, 망간, 코발트, 마그네슘, 실리콘, 탄탈룸, 타이타늄, 금, 은, 백금 및 팔라듐 등)을 회수하는 친환경 전해기술로의 응용이 가능한 원천기술임. 따라서 개발한 모든 기술은 국내외에 특허를 출원하였으며, 4개의 특허는 등록이 완료된 상태임.
□ 성능사양 및 기술개발수준
○ 비수계 전해공정 개발 및 DB화
○ 대상금속(Li, Mg, Si, Ti, Ta, Nd, Co, Mn, Au, PGMs)의 비수계 redox로 부터 상온 전해환원 확인
○ 전해 작동온도 150 ℃ 이하 달성
○ 금속별 회수율 90 % 이상 달성
○ 금속순도: 단위 금속별 전해 시 순도 99 % 이상 달성
○ 최적조건에서 에너지소비량 3 kWh/kg 이하 달성
○ 고속 전해를 위한 Si rich SiOx 분말 회수 공정 개발
○ 고활성/경량 금속의 전해에 적합한 이온성액체의 설계 및 합성 기술 개발
□ 활용계획
○ 금, 백금족 금속을 대상금속으로 하여 친환경 전해기술 개발을 일차 완료하였으며, 비수계 전해에 의한 나노촉매 합성 기술을 (주)리소스에 기술이전하였고 본 사업단의 2단계 사업에 참여하여 해당 기술을 실증 하고자 함
○ 실리콘의 비수계 전해기술은 실리콘 슬러지 재활용에 적용하는 연구를 위탁기관인 한양대가 본 사업단의 2단계 사업에 참여하여 해당 기술을 실증하고자 함
○ 경량금속의 친환경 전해기술은 폐전지 재활용에 적용하는 연구는 위탁 기관인 세종대가 본 사업단의 2단계 사업에 참여하여 해당 기술을 실 증하고자 함
( 출처: 요약서 3p )
Abstract
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IV. Results
1. Light metals
Light metals such as magnesium and lithium are usually recovered by pyrometallurgical processes where metal phases are obtained by direct melting or by reduction with reductants often after the additional formation steps of specific metal salts. Generally these reco
IV. Results
1. Light metals
Light metals such as magnesium and lithium are usually recovered by pyrometallurgical processes where metal phases are obtained by direct melting or by reduction with reductants often after the additional formation steps of specific metal salts. Generally these recovery processes have problems such as high operating temperature ( 600~2,000 ℃) high operating cost low energy efficiency (50~80% ) high energy consumption (~100 kWh/kg metal) environmental issues and waste management. Alternatively these metals could be recovered by electrolysis but its practicability is limited by the use of conventional aqueous electrolytes because of low reduction potential and high chemical activity of the metals in aqueous systems. However the properties of ionic liquids such as wide electrochemical window low vapor pressure and satisfactory ionic conductivity shed light on the expansion of electrolysis to the recovery of the light metals. The results of non-aqueous electrolysis for the light metals are as followings :
A. Lithium
(1) Redox behaviors of lithium on various electrode materials were investigated from a1-ethyl-3-methyl-Imidazoliuom bis(trifluoromethylsulfonyl)imide ([EMIM]Tf2N) and 1-methyl-1-propylpiridiniumbis(trifluoromethanesulfonyl)amide (PP13Tf2N) with lithium bis(trifluorome- thylsulfonyl)imide (LiTFSI). Cyclic voltammograms of gold electrode showed the possibility of the electrodeposition of metallic lithium with a higher reduction current of [EMIM]Tf2N than PP13Tf2N. The metallic lithium could be reduced on the gold electrode by the potentiostatic condition which was confirmed by various analytical techniques including X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. Electrodeposited lithium surface was uniform without dendrite and any impurities was not detected except trace oxygen which would originate from the exposure to air during handling for analysis.
(2) A new hydrometallurgical route was investigated for improvement in the recycling of valuable metals from electrodes of lithium batteries. The recycling process involves reductive acid leaching double solvent extraction and direct electro-winning in an organic solution. The dissolution rate of metal from the electrodes was up to 90% in 2 M sulfuric acid with hydrogen peroxide (10 vol% ) at 75 ℃ within 60 min. The improvement of dissolution by hydrogen peroxide seems to be due to reduction of Co(III) to Co(II) which can readily be dissolved. Cobalt and lithium were extracted into Cyanex 272 and a room-temperature ionic liquid of [EMIM] TFSI respectively whereas most nickel and manganese did not move to the organic phases. Lithium in the [EMIM] TFSI could be directly reduced as a form of metal by non-aqueous electrowinning. The dense electrodeposits were composed of metallic lithium and an alloy with a gold substrate.
B. Magnesium
(1) Redox behaviors of magnesium were investigated in three non-aqueous electrolytes.
Linear sweep voltammograms of magnesium on the copper electrode showed the possibility of electrowinning of metallic magnesium at room temperature. Morphology of the magnesium deposits could be controlled by controlling the applied current. The metallic magnesium could be easily and uniformly deposited on a copper electrode under galvanostatic conditions in THF solution of EtMgBr. The composition crystal structure and morphology of the pure magnesium films were confirmed by X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy. The electrodeposited magnesium was uniformly distributed on the copper electrode surface without dendrites or impurities and exhibited (002) crystal orientation.
(2) Electrochemical dissolution behaviors of magnesium alloy and its alloying elements were investigated in the electrolyte consisting of 1 M EtMgBr THF. The dissolution onset potentials for the alloying elements are in ascending order as follows magnesium > zinc > manganese > aluminum > copper. Based on their anodic polarization curves it was confirmed that the selective dissolution of magnesium from the magnesium alloy is possible by applying an adequate potential to obtain high purity magnesium. The dissolution behavior of the magnesium alloy in potentiostatic electrolysis depends on applied potential. If the applied potential is as high as 3 V, a rapid dissolution of the magnesium occurs which can eventually lead to the dendrite formation of magnesium on cathodic side. However the potentiostatic electrolysis at 1 V and 2 V generates a uniform magnesium deposit with no dendritic growth as confirmed by SEM. In addition EDS analysis shows a very strong peak of magnesium with no impurities detected.
Therefore the electrorefining of low purity magnesium or magnesium alloy scraps in non-aqueous electrolyte can be a feasible recycling process for high purity magnesium production.
(3) We can say that the eco-friendly electrolysis is a powerful tool for recovery of lithium and magnesium from the wastes as an alternatives of conventional processes of high-temperature operation.
2. Reactive and transition metals
Reactive and transition metals such as titanium neodymium and silicon are usually recovered by pyrometallurgical processes where metal phases are obtained by direct melting or by reduction with reductants often after the additional formation steps of specific metal salts. As mentioned above these recovery processes have problems such as high operating temperature high operating cost low energy efficiency high energy consumption environmental issues and waste management. The application of ionk liquids can make the expansion of electrolysis to the recovery of reactive metals rare earth metals and silicon.
A. Titanium
(1) Most of titanium metallurgical processes involve a combination of pyrometallurgy and hydrometallurgy and are generally expensive. The commercialized thermo-chemical chloride processes such as Kroll and Hunter processes are batch operations and need higher grade natural rutile or upgraded synthetic rutile and slag as the feed and the involvement of cost sensitive chlorination and thermo steps. Many improvements for the thermo-chemical processes have been made but they hold little potential for significant cost reductions beyond current technology. Direct hydrometallurgical leach processes are advantageous in processing abundant ilmenite ores low energy consumption and produce sufficiently high quality of pigment grade TiO2 products for a wide range of applications and major demand. Direct chloride leaching processes have been investigated intensively featuring purification by solvent extraction and reclaiming HCI by hydrolysis or pyro-hydrolysis.
(2) Redox behaviors of titanium at room-temperature were investigated in the ionic liquids of 1-ethyl-3-methyl-imidazoliumbis(trifluoromethyl sulfonyl) imide ([EMIM]Tf2N) and 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide ([BMPy]Tf2N) with TiCl4.
Cyclic voltammetry on a gold working electrode showed the possibility of the electrodeposition of metallic titanium. The
metallic titanium could be electrodeposited on the gold electrode under potentiostatic conditions as confirmed by various analytical techniques. In the [EMIM]Tf2N electrolyte with dissolved TiCl4, the electrodeposited titanium surface was more uniform than in [BMPy]Tf2N and no impurity was detected except trace oxygen and residual electrolyte components caused by contamination during handling for analysis.
B. Neodymium
(1) The suitability of 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMIMTFSI), room temperature ionic liquid for the electrodeposition of neodymium has been investigated in this study. According to the electrochemical spectroscopic and thermal evaluations the electrodeposition of neodymium in EMIMTFSI was performed by potentiostatic electrolysis at -2.3 V at 150 ℃ in order to stimulate the mass transfer and to lower solution viscosity. The current efficiency evaluated from the mass change of the anode was more than 90%. A black electrodeposit on a copper substrate was fine and formed uniformly neodymium particle was observed by SEM. It was also identified that the contents of metallic neodymium in electrodeposits were 48 from the evaluation of EDX. The electrodeposit was composed of most of metallic neodymium and a part of neodymium oxide as identified from XPS.
(2) Neodymium-iron-boron magnets (NdFeB magnets) is the most powerful permanent magnets that are used in various industries to require a strong magnetic field such as computer hard disk drives wireless tools servo motors electric power steering hybrid and electric vehicles and wind turbines generator. Recently NdFeB magnet scraps are increasing by increasing consumption of high-performed magnet with the development of the IT industry and electronic industry. Therefore lots of research has been reported that recycling or separation/recovery of magnet wasted as a resource of rare earth metals. The conventional metallurgical and recycling process of NdFeB magnet is very complicated operates at high temperature and involves the use of corrosive and toxic materials such as hydrochloric acid and sulfuric acid. It has been investigated recovery of neodymium from the magnet waste or scrap by simple electrolysis using EMIMTFSI at room-temperature. The electrochemical redox behaviors of neodymium and alloy elements wee systematically studied in the EMIMTFSI electrolyte at room temperature.
The neodymium salt from the electrolyte dissolved neodymium was also prepared as intermediates and re-dissolved in EMIMTFSI and selectively reduced on a cathode by electrowinning. In addition the selective dissolution and reduction behavior of neodymium were investigated under potentiodynamic and potentiostatic conditions for electrorefining.
C. Silicon
(1) Redox behaviors of silicon at room-temperature were investigated in the ionic liquids of 1-ethyl-3-methyl-imidazoliumbis(trifluoromethyl sulfonyl) imide ([EMIM]Tf2N) and 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide ([BMPy]Tf2N) with SiCl4.
Cyclic voltammetry on a gold working electrode showed the possibility of the electrodeposition of elemental silicon. The reduction current of silicon in [EMIM]Tf2N was higher than in [BMPy]Tf2N. The elemental silicon could be electrodeposited on the gold electrode under potentiostatic conditions as confirmed by various analytical techniques including X-ray diffraction X-ray photoelectron spectroscopy and scanning electron microscopy with energy-dispersive spectroscopy. In the [EMIM]Tf2N electrolyte with dissolved SiCl4, the electrodeposited silicon surface was more uniform than in [BMPy]Tf2N and no impurity was detected except trace oxygen caused by contamination during handling for analysis.
(2) As a recovery of elemental silicon from the sludge of silicon wafer process a process of mechanical separation-chlorine roasting-electrolysis has been suggested. The silicon sludge consisted of Si, SiC, machine oil and metallic impurities. The oil and metal impurities was removed by mechanical separation. The Si-SiC mixture was converted to silicon chloride by chlorine roasting at 1,000 ℃ for 1 hr and the silkon chloride was dissolved into an ionic liquid of [Bmpy]Tf2N as an electrolyte. Cyclic voltammetry results showed an wide voltage window of pure [Bmpy]Tf2N and a reduction peak of elemental Si from [Bmpy]Tf2N dissolved SiCl4 on gold electrode respectively. The silicon deposits could be prepared on the gold electrode by the potentiostatic electrolysis of -1.9 V vs. Pt-QRE. The elemental silicon uniformly electrodeposited was confirmed by various analytical techniques including XRD FE-SEM with EDS and XPS. Any impurity was not detected except trace oxygen contaminated during handling for analysis.
3. Precious metals
Precious metals such as gold platinum palladium and rhodium have many applications including in catalysis electronic devices and jewelry. However its limited resources are becoming depleted. To meet the future demand and conserve resources it is necessary to process spent precious metal-containing materials such as catalysts electronic scraps and used equipment. These materials are usually processed by pyro/hydrometallurgical processes consisting of thermal treatment followed by leaching precipitation or solvent extraction. The leaching of precious metals are usually using acidic and alkaline solutions in the presence of oxidizing agents such as nitric acid and hydrogen peroxide sodium cyanide and iodide solutions. The process generates to>dc nitrogen oxide and chlorine gases. This study reports new green solvent as an alternative of the toxic solvent can be improve the economks of the existing processes and reduce the environmental pollution.
A. Gold
(1) Redox behaviors of gold at room-temperature were investigated in the ionk liquids of 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMIMTFSI) with titanium tetrachloride (TiCl4) as a supporting electrolyte at room temperature. Cyclic voltammetry on a working electrode showed the possibility of the electrodeposition of metallic gold.
The gold could be electrodeposited on the cathode under potentiostatic conditions as confirmed by various analytical techniques including X-ray diffraction X-ray photoelectron spectroscopy and scanning electron microscopy with energy-dispersive spectroscopy. In the EMIMTFSI electrolyte with dissolved TiCl4, the electrodeposited gold surface was more uniform than in BMIMCI and no impurity was detected.
(2) The electrorefining of gold by simple electrolysis was investigated in the ionic liquid 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide (EMIMTFSI) with titanium
tetrachloride (TiCl4) as a supporting electrolyte at room temperature. From the cyclic voltammetry results optimal electrorefining conditions were identified for the selective dissolution of gold from an anode and for the selective reduction of gold on a cathode under potentiostatic conditions. This was done to obtain pure gold on a cathode surface. The compositions crystal structures and morphology of pure gold was confirmed by X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy. The gold was uniformly deposited on the platinum electrode surface by electrolysis without any impurities by non-aqueous electrolysis at room temperature.
B. Platinum group metals
(1) The car industry is one of the technologkal applications which more platinum-group metals (PGM) employs. Therefore the recovery of the PGMs from the car catalytic converters could be an important source to obtain these precious metals with economic and environmental consequences. In this work in order to suggest an environmentally friendly method for the recovery of PGMs electrolysis and purification by using non-aqueous solution were studied. In addition a new alternative to recover at least the 95% of the PGMs present in the car catalytic converters by the application of less aggressive corrosive or expensive reagents and conditions is proposed.
(2) Redox behaviors of PGMs at room-temperature were investigated in the ionic liquids of 1-butyl-3-methyl-imidazolium chloride (BMIMCI) at room temperature. Cyclic voltammetry on a working electrode showed the possibility of the electrodeposition of PGMs. Platinum and palladium was anodically dissolved out from the anode. The palladium could be selectively dissolved out at potentiostatic conditions of 0.6 V (vs. Pt-QRE) and selectively reduced on a carbon cathode at potentiostatic conditions of -1.2 V (vs. Pt-QRE). It was reported an interesting phenomena that the addition of hydrophobic ionic liquid, [C4mim] PF6 , into the water phase of hydrochloric acid aqueous solutions containing Pt(IV) Pd(II) and Rh(Ⅲ) chloric-complexing anions could induce the formation of a stable liquid-liquid two layered liquids coexisting medium for extraction and one-step separation of platinum palladium and rhodium. The transferring of PtCl62- into the [C4mim] PF6 bottom phase was proposed to be according with an anion exchange between PtCl62- and PF6- in ionic liquid. Therefore the separated ionic liquid phase provided an extended separation capacity than the literature reported ionic liquid based two-phase extraction systems.
(3) Surface activity of heterogeneous catalysts can be enhanced if their sizes are reduced to nanometers. However loose nanomaterials pose potential health and environmental risks. This work has been addressed by attachment of palladium nanoparticles on carbon fiber supports that have exceptionally high surface area per volume. It is seen that chemical functionalization provides some increase in nano-catalyst loading morphological modification is significantly more powerful. It has the potential to create orders of magnitude increase in catalytic activity within the same overall volume. The pulse electrolysis in non-aqueous electrolyte has been investigated in sufficient detail to provide significant control over the density and size of nanoparticles within a few seconds. The nanoparticles were seen to be metallic palladium having face centered cubic structure. Additionally the nano-particles were durable and remain attached to the base support after long periods of rapid rotation in water. These robust nano structures show promise in future applications such as sensors water purification systems fuel cell electrodes and hydrogen storage sponges.
( 출처: SUMMARY 16p )
목차 Contents
- 표지 ... 1
- 제 출 문 ... 2
- 요 약 서 ... 3
- 요 약 문 ... 6
- SUMMARY ... 14
- 목차 ... 23
- 제1장 서론 ... 25
- 제1절 연구개발과제의 개요 ... 25
- 1. 연구개발의 목적 및 필요성 ... 25
- 2. 연구개발대상 기술의 차별성 ... 30
- 제2절 연구개발의 국내외 현황 ... 31
- 1. 비수계 전해-이온성액체 ... 32
- 2. 리튬과 코발트 ... 46
- 3. 마그네슘 ... 56
- 4. 실리콘 ... 61
- 5. 백금족 금속 ... 68
- 제3절 연구개발의 내용 및 범위 ... 96
- 1. 연구개발의 최종목표 ... 96
- 2. 연도별 연구개발 목표 및 평가방법 ... 96
- 3. 연도별 추진체계 ... 99
- 제2장 연구개발 수행내용 및 결과 ... 102
- 제1절 연구개발 결과 및 토의 ... 102
- 1. 경량금속 ... 102
- 2. 고활성금속 ... 153
- 3. 전이금속과 실리콘 ... 188
- 4. 귀금속 ... 219
- 제2절 연구개발 결과 요약 ... 270
- 1. 경량금속의 친환경 전해 ... 270
- 2. 고활성 및 전이금속의 친환경 전해 ... 272
- 3. 귀금속의 친환경 전해 ... 274
- 제3장 목표 달성도 및 관련분야 기여도 ... 278
- 제1절 연도별 연구개발목표의 달성도 ... 278
- 제2절 정량적 연구성과 ... 280
- 제3절 관련분야의 기술발전 기여도(환경적 성과 포함) ... 289
- 제4장 연구개발결과의 활용계획 ... 291
- 제1절 연구개발 결과의 활용계획 ... 291
- 끝페이지 ... 291
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