• 한국분말재료학회지
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• 제21권4호
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• pp.286-293
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• 2014

The electrochemical properties of cells assembled with the $LiNiO_2$ (LNO) recycled from cathode materials of waste lithium secondary batteries ($Li[Ni,Co,Mn]O_2$), were evaluated in this study. The leaching, neutralization and solvent extraction process were applied to produce high-purity $NiSO_4$ solution from waste lithium secondary batteries. High-purity NiO powder was then fabricated by the heat-treatment and mixing of the $NiSO_4$ solution and $H_2C_2O_4$. Finally, $LiNiO_2$ as a cathode material for lithium ion secondary batteries was synthesized by heat treatment and mixing of the NiO and $Li_2CO_3$ powders. We assembled the cells using the $LiNiO_2$ powders and evaluated the electrochemical properties. Subsequently, we evaluated the recycling possibility of the cathode materials for waste lithium secondary battery using the processes applied in this work.

• 한국결정학회지
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• 제3권2호
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• pp.111-119
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• 1992

Czochralski법에 의해 alexandrite단길정을 육성 하였다. 결함과 인상속도, 회전속도, Beo의 순도 및 BeO와 Cr3+/Al3+ 치환비의 증발 손실보상 등 결정육성 요소의 관계를 규명하였다. 결과로서 1) 결정육성 원료로서 BeO의 순도는 99.99f) 이상의 고순도이어야 하고, 2) 증발손실 보상은 고품위의 결정을 육성하 기 위한 필수조건으로서 인상속도와 Cr3+/Al3+ 치환 비에 의존되며, 3) 적당한 인상 및 회전속도는 0. 5 ∼1.0mm/hr과 20∼25rpm으로 나타났다. 육성된 결정 은 (001) 방향으로 성장되었으며, 편광현미경으로 여러가지 형태의 결함을 관찰하였고 그 제거 방법을 논의 하였다. 또한 실온에서 흡수 및 형광방출 스펙트럼을 측정·비교하였다.

• Nuclear Engineering and Technology
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• 제24권2호
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• pp.163-167
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• 1992

고순도알루미늄중 불순물의 Parameter로 이용될수 있는 구리의 비파괴 방사화분석법의 고찰 및 23종의 극미량불순성분원소의 함량을 분석하였다. 즉 구리의 분석은 원자로의 속중성자에 의한 27Al(n,$\alpha$)24Na반응으로 생성되는 24Na의 방사능을 감소시키기 위하여 Thermal Column을 이용하였고 다른 조사공을 이용한 경우보다 약 100 배 정 도 방해 요인을 감소시킬 수 있었다. 24Na 에 의한 영향은 2-3 %범위 이하이었다. 이 방법에 의해 표준알루미늄(6 nine class)시료로부터 구리를 정량하였고 아울러 기타 불순원소들을 일상 방사화분석법에 의해 정량하였다. 구리의 함량은 0.54$\pm$0.08 ppm이었다. 이러한 결과는 문헌값과 비교할때 타당성이 있었고 일상분석에 이용할 수 있는 좋은 방법으로 여겨진다.

• Journal of Microbiology and Biotechnology
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• 제26권10호
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• pp.1781-1789
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• 2016

Glargine insulin is a long-acting insulin analog that helps blood glucose maintenance in patients with diabetes. We constructed the pPT-GI vector to express prepeptide glargine insulin when transformed into Escherichia coli JM109. The transformed E. coli cells were cultured by fed-batch fermentation. The final dry cell mass was 18 g/l. The prepeptide glargine insulin was 38.52% of the total protein. It was expressed as an inclusion body and then refolded to recover the biological activity. To convert the prepeptide into glargine insulin, citraconylation and trypsin cleavage were performed. Using citraconylation, the yield of enzymatic conversion for glargine insulin increased by 3.2-fold compared with that without citraconylation. After the enzyme reaction, active glargine insulin was purified by two types of chromatography (ion-exchange chromatography and reverse-phase chromatography). We obtained recombinant human glargine insulin at 98.11% purity and verified that it is equal to the standard of human glargine insulin, based on High-performance liquid chromatography analysis and Matrix-assisted laser desorption/ionization Time-of-Flight Mass Spectrometry. We thus established a production process for high-purity recombinant human glargine insulin and a method to block Arg (B31)-insulin formation. This established process for recombinant human glargine insulin may be a model process for the production of other human insulin analogs.

• 분석과학
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• 제33권1호
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• pp.1-10
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• 2020

Alpha lipoic acid, an antioxidant, is widely used for treatment of various diseases. It is a racemic mixture, with R-(+)-α lipoic acid exhibiting greater potency, bioavailability, and effectiveness than those of the S-form. Thus, selective R-(+)-α lipoic acid has been recently used in various applications, necessitating the development of a method to test the enantiomeric impurity in R-(+)-α lipoic acid. We developed a simple and fast high-performance liquid chromatography method using a new immobilized amylose-based chiral column (Chiralpak IA-3). Design of experiment was applied to accurately predict the effects and interactions among various factors affecting the analytical parameters and to optimize the chromatographic conditions. This optimized method could completely separate the two enantiomer peaks with a resolution > 1.8 within a short running time (9 min). Then, the optimized method was validated according to the guidelines of the International Conference on Harmonization and applied for quantification of S-(-)-α lipoic acid in some commercial R-(+)-α lipoic acid tromethamine raw material. Our results suggested that the developed method could be used for routine quality control of R-(+)-α lipoic acid products.

• 한국결정성장학회지
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• 제25권3호
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• pp.93-97
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• 2015

본 연구에서는 고순도 균질 마이크로 Ag 입자를 얻기 위하여 용매추출법과 RF-LPP법을 이용하여 Air 분위기에서 $500^{\circ}C$에서 3시간 동안 열처리하여 Ag 입자를 합성하였다. 합성된 마이크로 Ag 입자를 XRD에 의해 비교 분석한 결과 주요 peak들이 JCPDS card(No. 87-0719)와 일치하는 것을 확인하였다. RF-LPP법을 이용함으로써, 핵 생성 싸이트 제어를 통해 균질 마이크로 Ag 입자를 합성하였으며, 환원처리 후 산소의 함유가 줄어드는 것을 확인하였다. 본 연구를 통하여 재활용 기술에 큰 기여를 할 것이라 기대한다.

• 한국초전도ㆍ저온공학회논문지
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• 제19권2호
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• pp.19-24
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• 2017

Cryogenic milling which is a combined process of low-temperature treatment and mechanical milling was applied to fabricate high critical current density $(J_c)MgB_2$ bulk superconductors. Liquid nitrogen was used as a coolant, and no solvent or lubricant was used. Spherical Mg ($6-12{\mu}m$, 99.9 % purity) and plate-like B powder (${\sim}1{\mu}m$, 97 % purity) were milled simultaneously for various time periods (0, 2, 4, 6 h) at a rotating speed of 500 rpm using $ZrO_2$ balls. The (Mg+2B) powders milled were pressed into pellets and heat-treated at $700^{\circ}C$ for 1 h in flowing argon. The use of cryomilled powders as raw materials promoted the formation reaction of superconducting $MgB_2$, reduced the grain size of $MgB_2$, and suppressed the formation of impurity MgO. The superconducting critical temperature ($T_c$) of $MgB_2$ was not influenced as the milling time (t) increased up to 6 h. Meanwhile, the critical current density ($J_c$) of $MgB_2$ increased significantly when t increased to 4 h. When t increased further to 6 h, however, $J_c$ decreased. The $J_c$ enhancement of $MgB_2$ by cryogenic milling is attributed to the formation of the fine grain $MgB_2$ and a suppression of the MgO formation.

• 한국세라믹학회지
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• 제47권6호
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• pp.613-617
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• 2010

Ferro-Nickel slag is one of the by-products in Ferro-Nickel manufacturing process. The slag is composed of $SiO_2$, MgO, $Fe_2O_3$ and others. But the slag has been buried at landfill despite having valuable elements. This study tried to extract Mg ion and fabricate Mg compound from ferro-nickel slag using hydrochloric acid solution. Mg ion was extracted with Si, Fe and other ions in HCl solution. So reprocess was needed for gaining high purity Mg ion. It was thought that Si ion or $SiO_2$ precipitated in HCl solution and removed from solution in filtering process. Fe ion converted into $Fe(OH)_3$ after reacted with $NH_4OH$ and precipitated in HCl solution. After these process, the filtrate was composed of high purity Mg ion. $MgCl_2{\cdot}NH_4Cl{\cdot}6H_2O$ was obtained through drying of filtrate and this product was changed into MgO by burning process ($600^{\circ}C$-30 min). That is, 1st material or solution for manufacturing 2nd product was fabricated using acid dissolution method and other treatments.

• 한국주조공학회지
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• 제12권3호
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• pp.220-229
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• 1992

The degree of purification and the macrostructure of high purity aluminium were studied through the alternate stirring method in order to improve the nonuniformity of solute concentration in the unidirectional stirring method. The $2^3$ factorial design was done to examine the effects of experimental factors more qualitatively. In the relatively low stirring speed of 1500 rpm with alternate stirring mode, the uniform solute profile and refined grain structure were obtained due to strong washing effect and turbulent fluid flow. It was induced by the transition of the momentum boundary layer by alternation of the stirrer. It was concluded from this study that the alternate stirring mode was more effective to obtain the uniformity of solute even in the stirring speed of 1500 rpm. But the degree of purification decreased below the critical alternating period. When 2N(99.8wt.%) aluminium was used as the starting material the morphology of solid-liquid showed the cellular shape and the columnar grains were inclined to the direction of rotation. This inclined grain growth resulted from the difference of relative velocities of solid and liquid. The inclined angle was increased as the stirring speed increased and solidification proceeded. In the case of 4N aluminium, there was no inclined grain growth and it was confirmed from the macrostructure and SEM work that the morphology of solid-liquid interface was planar. From the factorial design, it was found that the alternate stirring mode showed poorer purification effect than that of unidirectional stirring mode at low speed(500 rpm). In addition, the factor that had the most significant effect on the degree of purification was the stirring speed.

• 한국진공학회지
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• 제12권2호
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• pp.136-143
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• 2003

본 논문은 비질량분리형 이온빔증착법에 이용하기 위한 고순도의 고주파 스퍼터타입 이온소스에 대한 특성을 평가했다. 고주파 구리 코일과 고순도 (99.9999 %)의 구리 타겟으로 이루어진 이온소스에 대한 기본적인 특성과 ULSI금속배선용 구리 박막으로의 응용가능성에 대해서 고찰하였다. 구리 타겟에 걸어주는 전압에 따른 구리 타겟에 흐르는 전류 특성을 고주파 전원 또는 아르곤 가스 압력을 변화시키면서 특성을 평가한 후 구리박막제작을 위한 조건에 대해서 고찰하였다. 박막 증착을 위한 기본적인 조건으로써, 타겟의 전압 -300 V와 고주파 전원 240 W, 그리고 아르곤 압력 9 Pa이 정해졌으며, 이 같은 조건에서 기판 바이어스 -50 V에서 증착된 구리 박막의 비저항값은 1.8 $\pm$ 0.1 $mu\Omega$cm로 이는 구리 벌크의 저항값(1.67 $\pm$ 0.1 $\mu\Omega$cm)에 근접한 값임을 알 수 있었다.