• 자원환경지질
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• 제56권2호
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• pp.155-166
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• 2023

COVID-19를 겪으면서 광물자원의 공급망 관리 중요성이 극대화되었다. 특히 수요 및 공급 관리가 어려운 광물자원은 우리나라가 적극적으로 추진하고 있는 소재부품산업의 원료확보 차원에서 공급망 관리가 중요하다. 본 연구에서는 광종별로 글로벌 공급위험과 공급위험 발생시 국내 경제적 영향의 유·무형 요인을 정량화하고 위험상태 행렬(criticality matrix-criticality level)을 이용하는 핵심광물을 선정하는 체계를 수립하고 평가를 수행하였다. 독과점성, 생산국가 불안정성, 사회환경정책 규제성, 수입 불안정성, 리스크 대응력, 시장규모, 시장 확장성, 경제적 중요성 등을 평가항목으로 하였다. 국내 신성장 사업에 활용되는 40여종의 광물을 평가하여 15종(Li, Pt, Co, V, REE, Mg, Mo, Cr, Ti, W, C, Ni, Al, Mn, Si)을 핵심광물로 선정하였다. 해당 결과는 자원안보 강화를 위한 정책 수립과 기업의 원료 포트폴리오 구성을 위한 의사결정 등에 활용될 수 있을 것으로 기대한다.

• 공업화학
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• 제7권5호
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• pp.888-901
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• 1996

V/Mo/P/Al/Ti-혼합 산화물 촉매상에서 고정층 적분식 반응기를 사용하여 공기로 1-펜텐과 시클로펜텐의 산화반응을 연구하였다. 고전환율에서 두 반응물들로부터 얻은 단일의 중요한 유기생성물은 무수말레인산이었고 동시에 소량의 무수프탈산을 얻었다. 한편, 1-펜텐 반응물로부터는 소량의 무수시트라콘산을 추가로 얻었다. 저전환율에서는 전체적으로 30개의 유기 산화 생성물들을 확인했으며, 그들중 일부는위에 언급된 3개의 무수물을 형성하기 위한 반응 중간체들 이었다. 전환율에 따른 유기 생성물들의 선택성을 근거로하여 무수말레인산, 무수프탈산 및 무수시트라콘산의 형성을 위한 반응경로를 제안했다. 한편, $310^{\circ}C$에서 공간속도의 감소에 따라 전환율과 무수말레인산의 선택성은 증가하였고, 무수말레인산의 최고선택성은 약 100%의 전환율에서 얻었다. $2{\cdot}10^4h^{-1}$의 일정한 공간속도에서 온도($300^{\circ}C{\sim}420^{\circ}C$)증가에 따라 전환율은 증가한 반면, 무수말레인산으로의 선택성은 시클로펜텐 산화반응의 경우 $370^{\circ}C$에서 약 39%의 최고값과 1-펜텐 산화반응의 경우 $400^{\circ}C$에서 약 30%의 최고값을 얻었다.

• Nuclear Engineering and Technology
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• 제45권7호
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• pp.847-858
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• 2013

Since 2001, a series of five irradiation test campaigns for atomized U-Mo dispersion fuel rods, KOMO-1, -2, -3, -4, and -5, has been conducted at HANARO (Korea) in order to develop high performance low enriched uranium dispersion fuel for research reactors. The KOMO irradiation tests provided valuable information on the irradiation behavior of U-Mo fuel that results from the distinct fuel design and irradiation conditions of the rod fuel for HANARO. Full size U-Mo dispersion fuel rods of 4-5 $g-U/cm^3$ were irradiated at a maximum linear power of approximately 105 kW/m up to 85% of the initial U-235 depletion burnup without breakaway swelling or fuel cladding failure. Electron probe microanalyses of the irradiated samples showed localized distribution of the silicon that was added in the matrix during fuel fabrication and confirmed its beneficial effect on interaction layer growth during irradiation. The modifications of U-Mo fuel particles by the addition of a ternary alloying element (Ti or Zr), additional protective coatings (silicide or nitride), and the use of larger fuel particles resulted in significantly reduced interaction layers between fuel particles and Al.

• 한국대기환경학회지
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• 제4권2호
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• pp.38-46
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• 1988

NOx is an important air pollution material which is generated when fossil fuels are burning, NOx removal in flue gas by selective catalytic reduction was studied over various catalysts in a fixed bed continuous flow reactor. The ranges of experimental conditions were at the temperatures between $200^\circ$C and $350^\circ$C, the $NH_3/NOx$ mole ratios between 0.8 and 1.4, oxygen concentrations between 1.5% and 3% and the space velocities between 5, 000 $hr^-1$ and 12, 500 $hr^-1$. The efficiency of NOx removal in the ranges of experimental conditions was highest at the temp. of 300$^\circ$C, oxygen concentration of 2.5-2.6% and $NH_3/NOx$ mole ratios of 1.0-1.2. The catalyst with high activity for NOx removal in flue gas was found to be $MoO_3-V_2O_5/TiO_2$.

• 한국전기전자재료학회논문지
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• 제26권6호
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• pp.441-445
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• 2013

ZnO nanowires on the a-, c- and m-plane oriented 4H-SiC substrates were grown by using a high temperature tube furnace. Ti/Au electrodes were deposited on ZnO nanowires and a-, c- and m-plane 4H-SiC substrates, respectively. The shape and density of the ZnO nanowires were investigated by field emission scanning electron microscope. It was found that the growth direction of nanowires depends strongly on growth parameters such as growth temperature and pressure. In this work, The sensitivity of nanowires formed a-, c- and m-plane oriented 4H-SiC gas sensor was measured at $300^{\circ}C$ with CO gas concentration of 80%. The nanowires grown on a-plane oriented 4H-SiC show improved sensing performance than those on c- and m-plane oriented 4H-SiC due to the increased density of nanowire on a-plane 4H-SiC.

• 마이크로전자및패키징학회지
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• 제12권1호
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• pp.21-26
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• 2005

The field effect transistors (FETs) were fabricated ell $Y_2O_3/Si(100)$ substrates by the conventional memory processes and sol-gel process using $(Bi,La)Ti_3O_{12}(BLT)$ ferroelectric gate materials. The remnant polarization ($2Pr = Pr^+-Pr^-$) int Pt/BLT/Pt/Si capacitors increased from $22 {\mu}C/cm^2$ to $30{\mu}C/ cm^2$ at 5V as the annealing temperature increased from $700^{\circ}C$ to $750^{\circ}C$. There was no drastic degradation in the polarization values after applying the retention read pulse for $10^{5.5}$ seconds. The capacitance-voltage data of $Pt/BLT/Y_2O_3/Si$ capacitors at 5V input voltage showed that the memory window voltage decreased from 1.4V to 0.6V as the annealing temperature increased from $700^{\circ}C$ to $750^{\circ}C$. The leakage current of the $Pt/BLT/Y_2O_3/Si$ capacitors annealed at $750^{\circ}C$ was about $510^{-8}A/cm^2$ at 5V. From the drain currents versus gate voltages ($V_G$) for $Pt/BLT/Y_2O_3/Si(100)$ FET devices, the memory window voltages increased from 0.3V to 0.8V with increasing tile $V_G$ from 3V to 5V.

• 한국전기전자재료학회논문지
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• 제25권2호
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• pp.91-95
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• 2012

ZnO thin films were deposited on p-type 4H-SiC substrate by pulsed laser deposition. ZnO nanowires were formed on p-type 4H-SiC substrate by furnace. Ti/Au electrodes were deposited on ZnO thin film/SiC and ZnO nanowire/SiC structures, respectively. Structural and crystallographical properties of the fabricated ZnO thin film/SiC and ZnO nanowire/SiC structures were investigated by field emission scanning electron microscope and X-ray diffraction. In this work, resistance and sensitivity of ZnO thin film/SiC gas sensor and ZnO nanowire/SiC gas sensor were measured at $300^{\circ}C$ with various CO gas concentrations (0%, 90%, 70%, and 50%). Resistance of gas sensor decreases at CO gas atmosphere. Sensitivity of ZnO nanowire/SiC gas sensor is twice as big as sensitivity of ZnO thin film/SiC gas sensor.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.197-197
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• 2016

Commercially pure titanium (CP Ti) and Ti-6Al-4V alloys have been widely used for biomedical applications. However, the use of the Ti-6Al-4V alloy in biomaterial is then a subject of controversy because aluminum ions and vanadium oxide have potential detrimental influence on the human body due to vanadium and aluminum. Hence, recent works showed that the synthesis of new Ti-based alloys for implant application involves more biocompatible metallic alloying element, such as, Nb, Hf, Zr and Mo. In particular, Nb and Hf are one of the most effective Ti ${\beta}-stabilizer$ and reducing the elastic modulus. Plasma electrolyte oxidation (PEO) is known as excellent method in the biocompatibility of biomaterial due to quickly coating time and controlled coating condition. The anodized oxide layer and diameter modulation of Ti alloys can be obtained function of improvement of cell adhesion. Manganese(Mn) plays very important roles in essential for normal growth and metabolism of skeletal tissue in vertebrates and can be detected as minor constituents in teeth and bone. Radio frequency(RF) magnetron sputtering in the various PVD methods has high deposition rates, high-purity films, extremely high adhesion of films, and excellent uniform layers for depositing a wide range of materials, including metals, alloys and ceramics like a hydroxyapatite. The aim of this study is to research the Mn coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetron sputtering for dental applications. Ti-29Nb-xHf (x= 0, 3, 7 and 15wt%, mass fraction) alloys were prepared Ti-29Nb-xHf alloys of containing Hf up from 0 wt% to 15 wt% were melted by using a vacuum furnace. Ti-29Nb-xHf alloys were homogenized for 2 hr at $1050^{\circ}C$. Each alloy was anodized in solution containing typically 0.15 M calcium acetate monohydrate + 0.02 M calcium glycerophosphate at room temperature. A direct current power source was used for the process of anodization. Anodized alloys was prepared using 270V~300V anodization voltage at room. Mn coatings was produced by RF-magnetron sputtering system. RF power of 100W was applied to the target for 1h at room temperature. The microstructure, phase and composition of Mn coated oxide surface of Ti-29Nb-xHf alloys were examined by FE-SEM, EDS, and XRD.

• 한국자원식물학회지
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• 제4권2호
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• pp.39-45
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• 1991

Proximate compositions of the roots of cultured and wild Codonopsis lanceolata were examined as tile basic reasearch for the study of their source of processed foods.No significant difference in the contents was found between the wild root and thecultivated at 3$0^{\circ}C$ in biotronroom. In view of the results to have measured mineralswhich is included in 14 sorts of Codonopsis lanceolata and surveyed their distribution.12 kinds of minerals including T1, Co, Ge, Sm, Mo, Sc, Be, Cd, As, Ga, Bi, ph are ne-vel or little included in almost source. Other twenty-one sorts of minerals (Ni, Se,Ba, Sb, Si, Ti, B, Li, Ifs, Ca, Sr, Mn, Fe, Cu, Zn, p, Al, Na, V, Cr, K) are more or less in-cluded in all source and Ca, Mg, p, K, and Fe are metals that are included in large qu-entities in comparison with others. No minerals difference in the contents was foundbetween the cultivated temperature. The content of elements of inorganic metal differsaccording to the part of C. lanceolata.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.325-328
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• 2005

Bainitic microalloyed steels have drawn a lot of attention because of high strength combined with high toughness. In order to process the alloys easily , it is necessary to get the alloys of high hardenability. Mo and B were added to enhance the hardenability, which was demonstrated by TTT simulation and microstructures. It was also identified using BNCT that B, hardenability raising element, was distributed more evenly as cooling rate went up. Examination of grain coarsening temperature depending upon austenitizing temperature revealed that V and Ti effectively inhibited the grain growth up to $1000^{\circ}C\;and\;1050^{\circ}C$ respectively.