• 한국전기전자재료학회논문지
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• 제20권4호
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• pp.308-317
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• 2007

We fabricated thermally-evaporated 10 nm-Ni/(poly)Si and 10 nm-$Ni_{0.5}Co_{0.5}$/(Poly)Si structures to investigate the microstructure of nickel silicides at the elevated temperatures required lot annealing. Silicides underwent rapid annealing at the temperatures of $600{\sim}1100^{\circ}C$ for 40 seconds. Silicides suitable for the salicide process formed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point tester was used to investigate the sheet resistances. A transmission electron microscope and an Auger depth profilescope were employed for the determination of vortical microstructure and thickness. Nickel silicides with cobalt on single crystal silicon actives and polycrystalline silicon gates showed low resistance up to $1100^{\circ}C$ and $900^{\circ}C$, respectively, while the conventional nickle monosilicide showed low resistance below $700^{\circ}C$. Through TEM analysis, we confirmed that a uniform, $10{\sim}15 nm$-thick silicide layer formed on the single-crystal silicon substrate for the Co-alloyed case while a non-uniform, agglomerated layer was observed for the conventional nickel silicide. On the polycrystalline silicon substrate, we confirmed that the conventional nickel silicide showed a unique silicon-silicide mixing at the high silicidation temperature of $1000^{\circ}C$. Auger depth profile analysis also supports the presence of this mixed microstructure. Our result implies that our newly proposed NiCo-alloy composite silicide process may widen the thermal process window for the salicide process and be suitable for nano-thick silicides.

• 대한수의학회지
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• 제13권1호
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• pp.85-102
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• 1973

In the event a population of animals is exposed to ionizing radiation, proper disposition of animals will minimize loss to the farmer and protect the public from unwholesome meat and dairy products. Clinical response is an important factor in considering salvage of animals for food following exposure to ionizing radiation whether the dose is lethal or not. It is the purpose of this report to present the discussions of blood picture and growth of y ung growing rabbits exposed to cobalt-60 gamma-irradiation. The experimental animals were Hyrnalayan rabbits of 65 days old. The body weight for all animals of the time of irradiation was approximately 450g. The 96 rabbits used in the experiment were allotted t groups of eight. Rabbits in one group served as controls and the others were exposed to single doses of 100, 200, 300, 400, 500, 600 and 700 Roentgens (R). The exposure does rate averaged 15 R per minute. Central blood was obtained by heart puncture. Erythrocyte and leukocyte enumerations and, determinations of hemoglobin in blood and hematocrit value were made in the usual manner. Erythrocyte counts, concentrations of hemoglobin in blood, and hematocrit readings dropped to the lowest value between 1 and 4 weeks postirradiation, returning towards the control values. But recovery was not complete at the time of the last determination on 6 weeks postirradiation. There was a progressive decrease with increasing radiation does in the above values. Mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were not affected by the irradiation. After irradiation of each does the numbers of total leukocyte and the absolute numbers of various types of white cell began to decrease rapidly, and reached a minimum after 2 weeks, returning towards normal levels. But recovery was not complete at the time of the last determination on 6 weeks postirradiation. The reductions in total leukocyte and differential counts as the radiation does increases were apparent. Relative neutrophilia was observed in each irradiated group because of more expense of lymphocytes after irradiation. Growth rate of the rabbits was not affected by 100 R of whloe-body irradiation, while rabbits irradiated with 200, 300, 400 and 500 R showed marked depression of growth rate. As the radiation does increases, a depression of growth rate was apparent. The rabbits exposed to 600 and 700 R ceased from growing and recovery was not recognized during the experimental period.

• 한국산학기술학회논문지
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• 제8권2호
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• pp.195-200
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• 2007

최소선폭 $0.1{\mu}m$ 이하의 살리사이드 공정을 상정하여 $10nm-Ni_{0.5}Co_{0.5}/70\;nm-Poly-Si/200\;nm-SiO_2$ 구조로부터 쾌속 열처리를 이용해서 실리사이드 온도를 $600{\sim}1100^{\circ}C$까지 변화시키면서 복합실리사이드를 제조하고 이들의 면저항의 변화와 미세구조의 변화를 면저항 측정기와 TEM 수직단면, 오제이 두께 분석으로 확인하였다. 기존의 동일한 공정으로 제조된 니켈실리사이드에 비해 제안된 니켈 코발트 복합실리사이드는 $900^{\circ}C$까지 저저항을 유지시킬 수 있는 장점이 있었고 20nm 두께의 균일한 실리사이드 층을 폴리실리콘 상부에 형성시킬 수 있었다. 고온 처리시에는 복합실리사이드와 실리콘의 전기적으로 상분리되는 혼합현상으로 고저항 특성이 나타나는 문제를 확인하였다. 제안된 NiCo 합금 박막을 70nm 높이의 폴리실리콘 게이트를 가진 디바이스에 $900^{\circ}C$이하의 실리사이드화 온도에서 효과적으로 산리사이드 공정의 적용이 기대되었다.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1757-1762
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• 2006

A solvent sublation using salphen as a ligand was studied and applied for the determination of trace Ni(II), Co(II) and Cu(II) in water samples. The fundamental study was investigated by a solvent extraction process because the solvent sublation was done by extracting the floated analytes into an organic solvent from the aqueous solution. The salphen complexes of Ni(II), Co(II) and Cu(II) ions were formed in an alkaline solution of more than pH 8 and then they were extracted into m-xylene. It was known that the each metallic ion formed 1 : 1 complex with the salphen and the logarithmic values of extraction constants for the complexes were 3.3 5.1 as an average value. Based on the preliminary study, the procedure was fixed for the separation and concentration of the analytes in samples. Various conditions such as the pH of solutions, the influence of $NaClO_4$, the bubbling rate and time of $N_2$ gas, and the type of organic solvent were optimized. The metal-salphen complexes could be extracted into m-xylene from the solution of more than pH 8, but the pH could be shifted to acidic solution of pH 6 by the addition of $NaClO_4$. In addition, the solvent sublation efficiency of the analytes was increased by adding $NaClO_4$. The recovery of 97-115% was obtained in the spiked samples in which given amounts of 0.3 mg/L Ni(II), 0.8 mg/L Co(II) and 0.04 mg/L Cu(II) were added.

• Bulletin of the Korean Chemical Society
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• 제28권1호
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• pp.68-72
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• 2007

A new PVC membrane potentiometric sensor that is highly selective to Hg2+ ions was prepared, using bis(2-hydroxybenzophenone) butane-2,3-dihydrazone (HBBD) as an excellent hexadendates neutral carrier. The sensor works satisfactorily in the concentration range of 1.0 × 10-6 to 1.0 × 10-1 mol L-1 (detection limit 4 × 10-7 mol L-1) with a Nernstian slope of 29.7 mV per decade. This electrode showed a fast response time (~8 s) and was used for at least 12 weeks without any divergence. The sensor exhibits good Hg2+ selectivity for a broad range of common alkali, alkaline earth, transition and heavy metal ions (lithium, sodium, potassium, magnesium, calcium, copper, nickel, cobalt, zinc, cadmium, lead and lanthanum). The electrode response is pH independent in the range of 1.5-4.0. Furthermore, the developed sensor was successfully used as an indicator electrode in the potentiometric titration of mercury ions with potassium iodide and the direct determination of mercury in some binary and ternary mixtures.

• 분석과학
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• 제20권6호
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• pp.496-501
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• 2007

ICP-AES를 이용하여 금을 분석할 때 감도가 가장 우수한 242.795 nm 파장은 분광학적 간섭을 일으키는 망간, 크롬, 코발트, 철 등의 원소들 때문에 광물에서 금의 분석은 불가능하다. 여기에서는 이들 원소들을 정량적으로 분리하는 분리방법을 연구하였다. 광물에서 금을 분리하기 위하여 광물을 용해한 산 용액에 MIBK 용매를 사용하여 정량적으로 추출하였다. 이때 질산과 염산의 혼산과 MIBK/n-hexane의 혼합용매는 효율적으로 금을 추출할 수 있었으며, 회수율은 97.5% 이상이었다.

• 대한화학회지
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• 제47권6호
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• pp.547-552
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• 2003

코발트와 니켈 이온을 4-(2-피리딜아조)레조루신올(PAR) 리간드와 킬레이트를 만들고 이 금속-PAR 킬레이트들을 역상 모세관 고성능 액체 크로마토그래피(RP-CpHPLC)로 분리와 정량을 하였다. 컬럼은 주로 Vydac C4 모세관 컬럼을, 이동상은 아세토니트릴(MeCN) 수용액을 사용하였다. 머무름 인자, k와 봉우리 높이에 대한 이동상의 pH와 MeCN 농도의 영향을 검토하여 분리와 정량의 최적 조건을 얻었다. 결과, 분리의 최적 이동상은 22.5% MeCN, pH 5.6이었고, Co(II) 이온의 정량은 이 조건에서 할 수 있었다. 그러나 Ni(II) 이온의 정량은 분리와 봉우리의 높이로부타 22.5% MeCN, pH 7.20이 보다 적합함을 확인하였다. 각각의 조건에서 Co(II)와 Ni(II) 이온의 검출한계(D.L., S/N=3)는 각각 $2.0{\times}10{-7}$ M(14.9 ppb)와 $1.0{\times}10{-6}$ M(59.2 ppb)였다.

• 대한화학회지
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• 제37권10호
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• pp.881-887
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• 1993

코발트(II) 이온의 정량을 위해 ${\iota}$-sparteine(SP)으로 변성된 탄소 반죽 전극(carbon paste electrode : CPE)을 제작하였다. 수용액 중의 코발트 이온을 CPE에 처리시킨${\iota}$-sparteine과 반응시켜서 착화합물 상태로 전극표면에 석출시킨 후, 이 착물을 전압-전류법을 사용하여 정량하였다. 또한 변성된 CPE의 전극반응을 순환 전압-전류법을 사용하여 아세트산/아세트산염 완충용액에서 조사하였다. 한번 사용한 전극은 산용액으로 처리하여 5회 이상 재사용할 수 있었다. CPE에 흡착된 Co(II)-SP 착물의 산화환원 전위는 0.17V / 0.27V였으며 산화피이크는 0.17V의 환원피이크를 지나야 나타나는 피크이다. 이는 전극표면의 SP와 용액내의 Co(II)이온이 착물을 형성하여 흡착되고, 이 전극표면에 형성된 착물이 산화환원되어 나타나는 피이크이다. 펄스차이 전압-전류법을 사용할 경우 $2{\times}10^{-7}$M 농도까지 직선적으로 감응함을 알 수 있었으며, 그 때의 상대표준 편차는 ${\pm}$5.6%이었다. 이 경우 검출한계는 $1.0{\times}10^{-7}$M이었다. 리간드와 착물을 형성할 것으로 예상되는 여러 금속이온에 대한 방해작용을 조사하였다.

• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1293-1296
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• 2006

In this study, a solid phase extraction method has been developed for the preconcentration and separation of the elements Cr(III), Fe(III), Co(II) and Pb(II) at trace levels by using a column packed with Amberlite XAD-1180 resin loaded with 4-(2-pyridylazo)-resorcinol (PAR) reagent. After preconcentrating, the metals retained on the column were eluted with 20 mL of 3 mol/L $HNO_3$ and then determined by flame atomic absorption spectrometry (FAAS). The factors affecting the recovery of the elements, such as pH, type and concentration of eluent, volume of sample and elution solution, and matrix components, were also ascertained. The recoveries of Cr(III), Fe(III), Co(II) and Pb(II) were found to be $99\;{\pm}\;4,\;97\;{\pm}\;3,\;95\;{\pm}\;3$ and $98\;{\pm}\;4$%, respectively, under the optimum conditions at 95% confidence level and the relative standard deviations found by analyzing of nine replicates were $\leq4.4$%. The preconcentration factors for Cr(III), Fe(III), Co(II) and Pb(II) were found as 75, 125, 50 and 75 respectively. The detection limits (DL, 3s/b) were 3.0 $\mu g/L$ for Cr(III), 1.25 $\mu g/L$ for Fe(III), 3.3 $\mu g/L$ for Co(II), and 7.2 $\mu g/L$ for Pb(II). The recoveries achieved by adding of metals at known concentrations to samples and the analysis results of Buffalo river sediment (RM 8704) show that the described method has a good accuracy. The proposed method was applied to tap water, stream water, salt and street dust samples.

• Nuclear Engineering and Technology
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• 제1권1호
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• pp.17-22
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• 1969

English sole(가재미종) 어편을 Polymylar bag에 밀봉하여 500 Krad의 감마선에 조사한 후 36일간의 0-2$^{\circ}C$ 저장기간중 조사한 것과 조사하지 않은 어편내에 축적되는 부패표시 물질과 총 균수를 측정하였다. 단백질 분해균을 직접 계수하기 위하여 Casein agar Plate 법을 만들어 저장기간중의 총균수비 대한 단백질분해균의 비율을 측정하는데 사용하였다. 500 Krad 선량 조사결과 어편의 총 균수는 10분의 1로 감축되었고 저장중 조사하지 않은 어편의 총균수 보다 훨씬 적어 1000분의 1선까지 내려갔다. 이에 따라 TVB와 TMA 축적도 억제되어 부패선을 넘지 못했으며 단백질 분해균 역시 총균수의 1% 이하선으로 감축되었으며 저장 기간중 이 선을 넘지 못했다. 반면에 조사하지 않은 어편엔 총 균수에 대한 이들의 비율은 저장기간중 점차 상승하여 22일째까지 총균수의 85.5%를 차지하였다. 방사선 조사로 인한 이 단백질 분해균의 선택적인 제거는 그 어편의 단백질 분해 부진 현상을 초래했다.