• 한국초전도ㆍ저온공학회논문지
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• 제11권2호
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• pp.7-10
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• 2009

Effects of $BaCO_3$ purity on the superconducting properties of top seeded melt growth (TSMG) processed $Y_{1+x}Ba_2Cu_3O_{7-y}$ (Y1+x, x=0.1 and 0.2) superconductors were investigated. $YBa_2Cu_3O_{7-y}$ (Y123) powder prepared using $BaCO_3$ with 99.75% purity and commercially available Y123 powder of 99.9% were used for the fabrication of single Y123 grain superconductors. $T_c$ values of the Y1+x samples prepared using low purity Y123 powder were slightly lower than those of the samples prepared using a high purity powder. In addition to the lower $T_c$, an anomalous peak effect in the intermediate magnetic fields was observed in Y1+x samples prepared using the low purity $BaCO_3$ powder. The slight decrease in $T_c$ and the anomalous peak effect are ascribed to the possible incorporation of a Y123 phase with impurity elements such as strontium and calcium included in the $BaCO_3$powder of 99.7%. The result suggests that the low purity $BaCO_3$ powder of a low price can be used as a raw power for the fabrication of single grain YBCO bulk superconductors.

• 분석과학
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• 제8권4호
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• pp.553-559
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• 1995

An extraction chromatographic method of separating rare earth impurities from high purity $Nd_2O_3$, $Sm_2O_3$, $Gd_2O_3$, $Er_2O_3$, $Dy_2O_3$ and $Yb_2O_3$ was studied by using $HCl-NH_4Cl$ as moving phase and P507 as stationary phase. After the impurities were enriched from the eluate by chelant-activated carbon, the active carbon was ashed and the ignited residue was used to prepare the sample electrode for spark source mass spectrometric determination. The impurities in 99.9999% rare earth oxide can be determined by the proposed method with recovery over 80%.

• Natural Product Sciences
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• 제24권4호
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• pp.288-292
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• 2018

High-performance countercurrent chromatography (HPCCC) coupled with reversed-phase highperformance liquid chromatography (RP-HPLC) method was developed to isolate dihydrophaseic acid 3'-O-${\beta}$-D-glucopyranoside (DHPAG) from the extract of Nelumbo nucifera seeds. Enriched DHPAG sample (2.3 g) was separated by HPCCC using ethyl acetate/n-butanol/water system (6:4:10, v/v/v, normal-phase mode, flow rate: 4.0 mL/min) to give 23.1 mg of DHPAG with purity of 88.7%. Further preparative RP-HPLC experiment gave pure DHPAG (16.3 mg, purity > 98%). The current study demonstrates that utilization of CCC method maximizes the isolation efficiency compared with that of solid-based conventional column chromatography.

• 대한핵의학회지
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• 제24권1호
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• pp.101-107
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• 1990

To develop $^{131}I-labelled$ m-iodobeneylguanidine $(^{131}I-MIBG)$, various experiments such as synthesis of MIBG, establishment of labelling conditions, determination of radiochemical purity, and examination of stability were carried out. 1) m-Iodobenzylguanidine (MIBG) sulfate was synthesized with a total yield of 62.4% by the condensation of m-iodobenzylamine hydrochloride with cyanamide via MIBG bicarbonate. Its physical properties, IR, $^1H-NMR$, and elemental analysis data were nearly identical to those of literature. 2) Freeze-dried or vacuum-dried kit vials were prepared from the mixture so as to contain MIBG (2 mg), ascorbic acid (10 mg), copper (II) sulfate (0.14 mg), and tin (II) sulfate (0.5 mg) per vial. Copper ( I ) catalyzed radioiodination of MIBG was carried out using kit vials and 0.01 M $H_2SO_4$ as solvent at $100^{\circ}C$ for 30 min under nitrogen atmosphere (optimal conditions). Labelling yield was 98% and radiochemical purity was 99.5%, respectively. 3) Solid-phase radioiodination of MIBG was carried out at $155^{\circ}C$ for 30 min using the prepared vials to contain MIBG (2 mg) and ammonium sulfate (10 mg). Duplicate reactions under the same conditions showed labelling yield of 95% and radiochemical purity of 99.5%. 4) $^{131}I-MIBG$ prepared either by catalytic or by solid-phase exchange method showed radio-chemical purity of 99% even after 3 days storing at room temperature.

• 멤브레인
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• 제26권5호
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• pp.381-390
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• 2016

본 연구에서는 고순도의 모데나이트(Mordenite) 입자를 합성하기 위하여 천연 제올라이트를 시드로 사용하여 시드의 농도 및 수열합성 시간에 따른 천연 제올라이트 시드가 합성에 미치는 영향을 고찰하였다. 그 결과 시드가 입자의 형성에 큰 영향을 끼치는 것을 확인할 수 있었고 시드를 3 g/100 g batch 주입하여 $140^{\circ}C$에서 72시간 동안 수열합성을 진행하였을 때 $1-2{\mu}m$ 사이즈의 고순도 모데나이트 입자를 합성할 수 있었다. 이를 통해 모데나이트 입자의 성장 기구를 규명할 수 있었으며, 모데나이트 입자 형성에 있어 시드는 첫째, 구형 모데나이트 전구체 형성 자리 공급의 역할과, 둘째 모데나이트 원료 물질 소스 역할을 한다는 것을 알 수 있었다. 합성된 모데나이트 입자의 가스 흡착량 분석 결과 $CO_2$ 기체의 흡착량이 97.19 mg/g로 다른 가스들에 비해 비교적 높은 흡착성능을 보였으며, $CO_2/H_2$의 선택도가 가장 우수한 것으로 나타났다. 따라서 이러한 결과들을 바탕으로 용도에 맞는 고순도 상의 모데나이트 입자를 합성할 수 있음을 확인하였고 보다 낮은 가격으로 우수한 분리성능을 갖는 분리막 소재개발에 활용할 수 있을 것이라 판단된다.

• 분석과학
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• 제23권1호
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• pp.97-101
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• 2010

(R)-N-3,5-dinitrobenzoyl (DNB) phenylglycinol로 부터 만들어진 키랄 선택제가 라세미 Nacylnaphthylalkylamines의 분리에 HPLC 키랄 정지상으로 이용된 바 있다. 본 연구에서는 (R)-phenylglycinol 유도체 키랄 선택제를 이용하여 키랄 크로마토그래피와 NMR 분광법에 의한 광학순도를 측정하였다. NMR과 HPLC 실험결과를 참값과 비교하여 각 광학순도 측정값의 정확도와 정밀도를 계산하였다. NMR 방법의 오차는 +2.2%, 평균 RSD는 4.54% 이었고, HPLC 방법의 오차는 -3.5%, 평균 상대표준편차는 3.23% 이었다.

• 농약과학회지
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• 제8권4호
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• pp.272-279
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• 2004

1,2-Diaminopropane을 출발물질로 하는 원예용 살균제 propineb의 제조공정을 최적화하였다. 독성 부 반응물인 1,2-propylenethiourea의 발생을 억제하기 위하여 상전이 촉매를 사용하였으며, 이때 product의 수율과 순도가 획기적으로 향상됨을 확인하였다. phosphonium 염계 상전이 촉매인 tetraphenylphosphonium bromide를 사용한 경우 생성물의 순도 96%, 수율 95% 및 부반응물 함량 1.7%로 가장 좋은 결과를 보였다. 또한 propineb의 현수성과 수화성을 개선하기 위하여 AES를 수화성 계면활성제로, APS를 현수성 계면활성제로 사용하였으며, 이들의 최적 조건은 AES $3.1\sim4.0%$, APS $4.0\sim5.0%$이었다.

• 한국분말재료학회지
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• 제15권1호
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• pp.6-12
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• 2008

[ $YBa_2Cu_3O_{7-y}$ ](123) powders were synthesized by the solid state reaction method using two different purity $BaCO_3$ powders (99.75% and 99.7% purity) and $Y_2O_3$ (99.9%) and CuO (99.9%) powders. The effect of $BaCO_3$ purity on the formation of a 123 phase and the superconducting properties were investigated. The mixtures of raw powders were calcined at temperature ranges of $800^{\circ}C-880^{\circ}C$ in air and finally made into a single grain samples by a melt processing with top seeding. It was found that a 123 phase was well formed at temperature above $870^{\circ}C$, but the purity effect on the 123 formation was negligible. The single-grain 123 samples prepared from the different $BaCO_3$ powders showed the same $T_c$ value of 90.5 K and similar $J_c$ values about $10^4\;A/cm^2$ at 0 T and 77 K, and $10^3\;A/cm^2$ at 2 T and 77 K. This result indicates that the low purity, cheap price $BaCO_3$ powder can be used as a raw material for the fabrication of single-grain, high-$J_c$ superconducting levitator.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.409-412
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• 2001

The high purity manganese oxides were made from the dust, generated in AOD process that produces a medium-low carbon ferromanganese and collected in the bag filter. Manganese oxide content in the dust was about 90%, and its phase was confirmed as Mn₃O₄. In the extraction of manganese, because of remaining amorphous MnO₂, the dust was reduced to MnO by roasting with charcoal. The pulp density of the reduced dust can control pH of the solution more than 4 and then Fe ion is precipitated to a ferric hydroxide. Because a ferric hydroxide co precipitates with Si ion etc, Fe, Si ion was removed f개m the solution. Heating made water to be volatized and nitrates was left in reactor Then nitrates were a liquid state and stirring was possible. Among the nitrates in reactor, only the manganese nitrate which have the lowest pyrolysis temperature pyrolyzed into β-MnO₂powder and NO₂(g) at the temperature less than 200℃. When the pyrolysis of manganese nitrate has been completed about 90%, injection of water stopped the pyrolysis. Nitrates of impurity dissolved and the spherical high purity β-MnO₂powders were obtained by filtering and washing. Mn₂O₃or Mn₃O₄ powder could be manufactured from β-MnO₂powder by controlling the heating temperature. Lastly, a manufactured manganese oxide particle has 99.97% purity.

• KSBB Journal
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• 제25권5호
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• pp.449-452
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• 2010

크라운 에테르로부터 유도된 키랄고정상에서 역상용매를 이동상으로 사용하여 국내외에서 시판되고 있는 광학이성질체 의약품인 레보티록신 나트륨의 광학순도 측정을 위한 새로운 직접적인 광학분리 분석법을 개발하여 매우 좋은 결과를 얻었다 ($\alpha$ = 2.15, Rs = 4.05). 시판하고 있는 레보티록신 나트륨의 광학순도를 키랄고정상을 이용하여 직접적인 광학분리방법으로 측정하는 실험은 현재까지 한 편의 연구결과 외에는 보고되어 있지 않는데 [4] 본 연구에서 새롭게 개발한 전처리과정과 HPLC 분석조건을 이용하여 현재 국내외에서 판매되고 있는 레보티록신 나트륨 주성분의 의약품 정제의 광학순도를 측정하였다. 레보티록신 나트륨의 광학순도를 측정한 광학분리 실험결과에서 하나의 제품을 제외하고는 99% 이상의 높은 광학순도를 보여주고 있음을 확인할 수 있었다. 본 연구의 편리하고 용이한 신규 광학분리 분석법이 국내외에서 상용되는 레보티록신 나트륨 제품의 품질 확인과 양질의 키랄의약품을 개발하고 제품을 관리하는데 매우 도움이 되리라 기대한다.