• 전기화학회지
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• 제9권2호
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• pp.64-69
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• 2006

초음파분무열분해법과 한 단계의 후열처리로 이차상이 없는 Al이 첨가된 $Li(Ni_{1/3}Co_{1/3}Mn_{1/3-x}Al_x)O_2$ (x=0.0, 0.005, 0.01. 0.05) 리튬이차전지용 양극활물질을 합성하였다. 합성된 분말은 Al의 첨가량이 많아짐에 따라서 $I_{003}/I_{104}$ 비는 감소하고 입자가 커지는 경향을 보였다. 상온에서 전류밀도 1C의 rate로 $3.0\sim4.5V$ 범위에서 충방전 시험한 결과, Al 치환량이 0.5와 1.0 at%에서는 초기용량이 180과 $184mAhg^{-1}$으로 치환하지 않았을 때의 $182mAhg^{-1}$과 차이가 없었으며, 싸이클 특성도 치환하지 않은 것과 0.5, 1.0 at% 치환한 조성에서 각각 81, 77, 81%의 방전용량이 유지되었다. 그러나 $3.0\sim4.6V$에서는 치환효과가 확실하게 나타나서, 50 싸이클 후의 치환하지 않은 것의 방전용량은 초기용량의 30%가지 감소한데 비하여 Al을 0.5 at% 치환한 것은 70%를 유지하였다. 치환에 의한 싸이클 특성 향상은 XPS 분석 결과 Al 치환이 $Mn^{3+}$의 양을 감소시켰기 때문인 것으로 사료되었다.

• 한국산업보건학회지
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• 제8권2호
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• pp.209-223
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• 1998

The aim of this study was to evaluate welders' exposure to hexavalent chromium (Cr(VI)) and nickel (Ni) during welding operations in a Korean shipyard. The airborne Cr(VI) and Ni concentrations were measured during metal inert gas (MIG) welding on mild and stainless steel, and manual metal arc (MMA) welding on mild steel. The geometric mean (GM) of Cr(VI) concentrations inside the welding helmet during MIG welding on mild steel were $0.0018mg/m^3$ inside a ship section, and $0.0015-0.0026mg/m^3$ at the welding shops. All of the personal breathing zone air samples were below the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value ($TLV^{(R)}$) of $0.01mg/m^3$. Conversely, eighty-eight percent(21 of 24) of the personal breathing zone air samples exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit of $0.001mg/m^3$. Ni was not detected on 20 of 23 air samples collected during MIG welding on mild steel. The three Ni samples above the limit of detection ranged from 0.015 to $0.044mg/m^3$. The GM of Cr(VI) concentrations during MMA welding on mild steel were $0.0013mg/m^3$, but Ni was not detected in the air samples during this operation. It is assumed that the airborne Cr(VI) and Ni during mild steel welding were derived from the base metals which contained about 0.03% Cr and 0.03% Ni. The GM of airborne total Cr, Cr(VI) and Ni concentrations during MIG welding on stainless steel were 4.02, 0.13 and $0.86mg/m^3$, respectively, and the levels of Cr(VI) and Ni were above the ACGIH-$TLV^{(R)}$. Cr(VI) comprised about 35.5% of the total chromium(Cr) from MIG welding on mild steel, and about 8.4% of total Cr from MIG welding on stainless steel. The ratios of Cr(VI) to total Cr were significantly different among welding shops. It was concluded that welders were exposed to high levels of Cr(VI) and Ni during welding on stainless steel, and were exposed to low levels of Cr(VI) even during welding on mild steel.

• 대한방사선기술학회지:방사선기술과학
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• 제38권4호
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• pp.347-353
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• 2015

디지털 흉부단층합성법 검사에서 부가필터 사용에 따른 환자의 선량과 화질의 특성을 비교해보고자 하였다. 부가필터의 종류는 구리, 알루미늄, 니켈을 사용하였으며, 이 때 각 각의 부가필터에 따른 유효선량, 면적선량을 측정해 보았고, 화질의 물리적 평가방법으로 signal to noise ratio (SNR)과 contrast to noise ratio (CNR)을, 시각적 평가방법으로 contrast detail (CD) phantom을 이용한 CD 곡선을 비교하였다. 그 결과 부가필터별 조사선량이 비슷한 두께는 0.3 mmCu, 3 mmAl, 0.3 mmNi 였으며 부가필터를 사용하지 않았을 때 보다 조사선량 값이 평균 33.1% 감소하였다. 각 필터 별 dose area product (DAP) 선량값을 측정한 결과 Ni를 사용하였을 때 선량이 72.9% 감소하여 가장 낮았으며, 필터별 DAP 값은 통계적으로 유의한 차이를 보였다(p<0.01). 유효선량은 Ni를 사용하였을 때 가장 낮은 선량 값을 보였고, 필터를 사용하지 않았을 때 0.102 mSv에 비해 48.0% 감소하였다. CD phantom에 의한 시각적 화질평가에서는 각 필터별로 비슷한 양상을 나타냈으며, 3가지 부가필터를 사용 하였을 때 S NR과 CNR은 평균 19.07, 1 8.17% 감소함을 보였다. 결론적으로 디지털 흉부 단층합성법 검사에서 부가필터로 Ni을 사용할 경우 유효선량 및 DAP 선량 감소, 화질에서 가장 적절함을 알 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제6권1호
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• pp.37-46
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• 1985

Development of a dental Ni-Cr alloy system for porcelain veneering crown and bridge was studied in this research. The principles of alloy design were a) It should not contain toxic beryllium. b) It should have low melting Point. c) It should be easily ground and polished. d) It should possess an adequate strength to resist the deformational force In the mouth. e) It should be bondable Ivith porcelain by chemically. After investigating the effect of minor elements such as boron and rare earth metals on the mechanical properties of the Ni-Cr alloy system, the compromised ideal composition for dental use was determined. The composition was l9.6%, Cr, 5.6% Mo, 3.4% Si, 1, 0% Fe, 0.01% Ti, 0.5-1.0% B, 0.2-0.6% misch metal, balance Ni. To compare the performance of experimental alloy with commercially available alloys, the properties such as strength, melting point, and bond strength were measured. The results Ivere as follows: a) Boron increases the strength of the alloy but reduces the elongation. b) Misch metal increases the strength when the boron content is low, but does not increase the strength when boron content is high. And it reduces the elongation drastically, c) Mechanical strength of the experimental alloy was not superior to commercially available Be containing alloy, but handling performance such as castability, ease of granting and polishing, and cuttability were superior to the Be containing alloy.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.161-167
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• 2018

In this study, transition metal coated carbon nanofibers (CNFs) were synthesized and applied as anode materials of Li secondary batteries. CNFs/Ni foam was immersed into 0.01 M transition metal solutions after growing CNFs on Ni foam via chemical vapor deposition (CVD) method. Transition metal coated CNFs/Ni foam was dried in an oven at $80^{\circ}C$. Morphologies, compositions, and crystal quality of CNFs-transition metal composites were characterized by scanning electron microscopy (SEM), Raman spectroscopy (Raman), and X-ray photoelectron spectroscopy (XPS), respectively. Electrochemical characteristics of CNFs-transition metal composites as anodes of Li secondary batteries were investigated using a three-electrode cell. Transition metal/CNFs/Ni foam was directly employed as a working electrode without any binder. Lithium foil was used as both counter and reference electrodes while 1 M $LiClO_4$ was employed as the electrolyte after it was dissolved in a mixture of propylene carbonate:ethylene carbonate (PC:EC) at 1:1 volume ratio. Galvanostatic charge/discharge cycling and cyclic voltammetry measurements were taken at room temperature using a battery tester. In particular, the capacity of the synthesized CNFs-Fe was improved compared to that of CNFs. After 30 cycles, the capacity of CNFs-Fe was increased by 78%. Among four transition metals of Fe, Cu, Co and Ni coated on carbon nanofibers, the retention rate of CNFs-Fe was the highest at 41%. The initial capacity of CNFs-Fe with 670 mAh/g was reduced to 275 mAh/g after 30 cycles.

• 한국결정학회지
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• 제10권1호
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• pp.88-93
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• 1999

The complex [Ni(L)](ClO4)2 (1) (L=2,13-bis(2-pyridylmethyl)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.1807.12]docosane) has been synthesized and characterized by X-ray crystallography. (1) crystallizes in the triclinic, space group P, with a=10.948(2), b=10.948(2), c=14.911(4) , α=93.73(2), β=93.77(2), γ=99.29(2)o, V=1754.8(7) 3, Z=2, R1(wR2) for 5217 observed reflections of [I>2σ(I)] was 0.048(0.099). The coordination environment around nickel(II) ion shows a distorted octahedron with four secondary and tertially amines of the macrocycle and two nitrogen atoms of pyridylmethyl groups.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.373-378
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• 2007

A micro organism Agrobacterium tumifacient as an immobilized cell on a solid support was presented as a new biosorbent in a simple and sensitive spectrophotometry determination of Ni(II) in various samples using 4-hydroxy benzaldehyde-4-bromophenyl hydrazone as a color developing agent (λmax 497 nm) at pH 4.0 ± 0.2. Beer's law was obeyed over the range of 0.01-0.1 μg L-1. The molar absorptivity and Sandell's sensitivity were 1.285 × 105 L mol-1cm-1 and 0.007245 μg cm-2 respectively. Under these conditions, the preconcentration factor obtained was 82, and the detection limit achieved was 0.05 μg L-1. The detailed study of various interfering ions made the method more sensitive and selective. The recovery of Ni(II) from various samples range from 97.75 to 99.35%. The present method was successfully applied for the determination of Ni(II) in spiked, natural water and alloy samples. The proposed method was compared with reported methods in terms of Student's ‘t'-test and Variance ratio ‘f'-test which indicates that there is no significant difference between proposed and literature method at 95% confidence level.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.193-195
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• 1994

In this study, the structural, dielectric and piezoelectrical properties of $xPb(Mg_{1/2}W_{1/2})O_3-(1-x)[0.41Pb(Ni_{1/3}Nb_{2/3})O_3-0.36PbTiO_3-0.23P Zr)_3]$ (x=0, 0.01, 0.02, 0.03, 0.04, 0.05) system ceramics were investigated. The dielectric constant ${\varepsilon_{33}}^{\tau}$ at loon temperature increased up to 3mol% PMW and decreased with further PMW content. The specimen with 1mol% $Pb(Mg_{1/2}W_{1/2})O_3$, which has the ${\varepsilon_{33}}^{\tau}=5509$, kp=59[%] and $d_{33}=758{\times}10^{-12}[C/N]$, exhibits good characteristics.

• 대한금속재료학회지
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• 제48권1호
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• pp.62-70
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• 2010

Leaching and solvent extraction experiments have been performed to develop a hydrometallurgical process for the recovery of nickel and cobalt from nickel laterite ore with high magnesium content. Most of the nickel and magnesium in the laterite ore dissolved at leaching conditions of $80^{\circ}C$ and 100 g/L sulfuric acid concentration. while half of the cobalt and iron were leached at the same conditions. Solvent extraction experiments were carried out with D2EHPA and saponifed D2EHPA from a synthetic solution containing Ni, Co, and Mg. The extraction percentage of Co, Mg. and Ni by D2EHPA was very low in a pH range of 4.4 to 7.3. while the extraction percentage sharply increased by using saponified D2EHPA. The stripping percentage of the metals from the saponified D2EHPA increased with sulfuric acid concentration and reached 99.9% at 1 M $H_2SO_4$ solution.

• 광물과 암석
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• 제34권1호
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• pp.1-14
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• 2021

운산 금 광상은 한반도의 3대(대유동 광상, 광양 광상) 금 광상중의 하나였다. 이 광상의 지질은 선캠브리아기의 변성퇴적암류와 중생대의 반상화강암으로 구성된다. 이 광상은 선캠브리아기의 변성퇴적암류와 중생대의 반상화강암내에 발달된 단층대를 따라 충진한 함 금 석영맥 광상으로 조산형 금 광상에 해당된다. 이 광상의 석영맥은 광물조합에 따라 1) 방연석-석영맥형, 2) 자류철석-석영맥형, 3) 황철석-석영맥형, 4) 페크마틱 석영맥형, 5) 백운모-석영맥형 및 6) 단순석영맥형으로 분류된다. 연구된 석영맥은 황철석-석영맥형이며 견운모화작용, 녹니석화작용 및 규화작용이 관찰된다. 백색운모는 유색대에서 백색석영, 황철석, 녹니석, 금홍석, 모나자이트, 저어콘, 인회석, 칼리장석 및 방해석 등과 함께 세립질 내지 중립질 입단으로 산출된다. 이 백색운모의 화학조성은 (K0.98-0.86Na0.02-0.00Ca0.01-0.00Ba0.01-0.00 Sr0.00)1.00-0.88(Al1.70-1.57Mg0.22-0.09Fe0.23-0.10Mn0.00Ti0.04-0.02Cr0.01-0.00V0.00Ni0.00)2.06-1.95 (Si3.38-3.17Al0.83-0.62)4.00O10(OH2.00-1.91F0.09-0.00)2.00로써 이론적인 이중팔면체형 운모류 값보다 Si가 높고 K, Na, Ca는 낮다. 이 광상의 엽리상 석영맥에서 산출되는 백색운모의 화학조성 변화는 팬자이틱(phengitic) 또는 Tschermark 치환[(Al3+)VI+(Al3+)IV <-> (Fe2+ 또는 Mg2+)VI+(Si4+)IV] 및 직접적인 (Fe3+)VI <-> (Al3+)VI 치환에 의해 일어났음을 알 수 있다. 엽리상 석영맥에서 산출되는 녹니석의 화학조성은 (Mg1.11-0.80Fe3.69-3.14Mn0.01-0.00Zn0.01-0.00K0.07-0.01Na0.01-0.00Ca0.04-0.01Al1.66-1.09)5.75-5.69 (Si3.49-2.96Al1.04-0.51)4.00O10 (OH)8로써 이론적인 녹니석보다 Si 함량이 높다. 이 녹니석의 화학조성 변화는 팬자이틱(phengitic) 또는 Tschermark 치환(Al3+,VI+Al3+,IV <-> (Fe2+ 또는 Mg2+)VI+(Si4+)IV) 및 팔면체적 Fe2+ <-> Mg2+ (Mn2+) 치환에 의해 일어났음을 알 수 있다. 따라서 운산 광상의 엽리상 석영맥 및 변질광물은 조산운동 시 연성전단(ductile shear) 시기에 형성되었음을 알 수 있다.