• 한국결정성장학회지
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• 제27권6호
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• pp.303-308
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• 2017

여러 가지 금속을 에칭하기 위하여 사용된 $FeCl_3$ 폐용액은 유가금속인 니켈을 함유하고 있다. 본 연구에서는 염화철을 재생하고 남은 니켈 함유 에칭폐액으로부터 니켈을 고순도의 탄산니켈 결정분말로 회수하고자 하였다. 5 % NaOH 수용액을 이용하여 pH 4의 조건에서 1차적으로 철 성분의 불순물을 약 97 % 제거하고 추가적으로 남은 불순물을 제거하기 위하여 용매추출제 D2EHPA(Di-(2-ethylhexyl) phosphoric acid)를 사용하여 불순물로서 존재하는 금속이온들을 약 99% 제거하였다. 그 후 불순물이 제거된 염화니켈 용액에 탄산나트륨과의 반응을 통하여 99.9 % 이상의 순도를 가진 탄산니켈분말을 얻을 수 있었다.

• 한국표면공학회지
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• 제28권2호
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• pp.83-91
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• 1995

A new method for preparation of thin nickel foam for Ni-MH battery was investigated. In this method, fine graphite powders of $1\mu\textrm{m}$～$2\mu\textrm{m}$ diameter were pasted into pores of thin polyurethane foam film in order to supply electric conducting seeds for nickel deposition by electroless plating reaction. After electroless plating, remaining polyurethane foam was removed chemically by organic solvent treatment and graphite particles also removed by ultrasonic cleaning. Porosity of formed nickel foam was about 85% During electroplating, porosity of the nickel foam decreased less than 5% up to $30\mu\textrm{m}$ coating thickness. And then it was electroplated and heat-treated to improve mechanical strength and ductility. Finally, thin nickel foam for Ni electrode of Ni-MH battery with 80% porosity and $350\mu\textrm{m}$～X$400\mu\textrm{m}$ thickness was obtained.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.602-605
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• 1999

We dried emitting layer of EL device at 30, 80, I20 and $150^{\circ}C$ for Ihr to investigate the effects to the emission characteristics of devices. PL intensity of P3HT thin film decreased with increasing the drying temperature. But, the EL intensity and stability of device with emitting layer dried at $150^{\circ}C$ were the best. We think it s because of absence of water and remaining solvent in P3HT emitting layer. So, We suggest that the drying temperature of emitting layer of EL device should be select slightly low temperature than its glass transition temperature.

• Composites Research
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• 제29권4호
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• pp.145-150
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• 2016

Polyvinylidene fluoride (PVDF)는 압전성을 나타내는 대표적인 고분자로 1960년대부터 많은 연구가 진행되어 왔다. PVDF는 반결정의 고분자로써 5가지의 결정 구조(${\alpha}$, ${\beta}$, ${\gamma}$, ${\delta}$, 그리고 ${\varepsilon}$형)로 구성되어 있다. ${\alpha}$형과 ${\delta}$형 결정은 전기적으로 반응하지 않는 무극성 결정구조이나 ${\beta}$형, ${\gamma}$형 그리고 ${\varepsilon}$형은 전기적으로 반응하는 극성 결정구조이다. 그 중에서도 ${\beta}$형 결정구조는 트랜스 형 분자 쇄가 평행으로 충진 된 형태로서 PVDF 단위체가 갖는 영구 쌍극자가 모두 한 방향으로 배열되어 있는 구조이기 때문에 자발 분극이 커지게 되고 압전성을 나타내게 된다. 일반적으로 ${\beta}$형 결정구조는 연신을 통한 ${\alpha}$형 결정구조의 변환을 통하여 얻을 수 있고, 연신 후 후처리 공정을 통해 그 양을 증가시킬 수 있다. 습식방사로 제조된 PVDF 섬유는 응고욕에서 극성 용매의 확산 메커니즘에 의해 ${\beta}$형 결정구조가 형성되는 장점을 가지고 있지만 극성 용매가 빠져나감과 동시에 섬유 고화가 진행되기 때문에 용매의 확산 경로가 섬유 내부 기공으로 남게 되는 단점을 가지고 있다. 이 기공은 폴링(Poling) 공정에서 전기장에 의한 분극을 방해하여 그 효과를 감소시키는 역할을 한다. 또한, PVDF 섬유가 압전 특성을 필요로 하는 응용분야에 사용되기 위해서는 섬유 가공 후에 전극이 반드시 부착되어야 하는데 섬유 형태로 제조된 PVDF에 전극을 형성하기는 매우 어렵다. 본 연구에서는 압전성을 갖는 PVDF 섬유를 습식 방사와 건식 방사의 혼합 공정으로 제조하여 기공 문제를 해결하였고, 전극이 섬유 내부에 삽입된 Core/Shell 형태의 PVDF 섬유를 제조하여 까다로운 전극형성 문제를 해결하였다.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3459-3464
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• 2014

Synthesis and structural characterization of mercury(II) halides and perchlorate complexes (1-4) of bis-$OS_2$-macrocycle (L) are reported. L reacts with mercury(II) chloride and bromide to yield an isostructural 2D coordination polymers with type $[Hg(L)X_2]_n$ (1: X = Cl and 2: X = Br). In 1, each Hg atom which lies outside the cavity is six-coordinate with a distorted octahedral geometry, being bound to four adjacent ligands via monodentate Hg-S bonds and two remaining sites are occupied by two terminal chlorido ligands to form a fishnet-like 2D structure. When reacting with mercury(II) iodide, L afforded a 1D coordination polymer $\{[Hg_2(L)I_4]{\cdot}CHCl_3\}_n$ (3) in which each exocyclic Hg atom is four-coordinate, being bound to two sulfur donors from different ligands doubly bridging the ligand molecules in a head-to-tail mode. The coordination sphere in 3 is completed by two iodo terminal ligands, adopting a distorted tetrahedral geometry. On reacting with mercury(II) perchlorate, L forms solvent-coordinated 1D coordination polymer $\{[Hg_2(L)(DMF)_6](ClO_4)_4{\cdot}2DMF\}_n$ (4) instead of the anion-coordination. In 4, the Hg atom is five-coordinate, being bound to two sulfur donors from two different ligands doubly bridging the ligand molecules in a side-by-side mode to form a ribbon-like 1D structure. The three remaining coordination sites in 4 are completed by three DMF molecules in a monodentate manner. Consequently, the different structures and connectivity patterns for the observed exocyclic coordination polymers depending on the anions used are influenced not only by the coordination ability of the anions but also by anion sizes.

• Asian Pacific Journal of Cancer Prevention
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• 제17권8호
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• pp.3835-3838
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• 2016

Background: Breast cancer is one of the most frequent cancer types within female populations. Silibinin is a chemotherapeutic agent ative against cancer. Niosomes are biodegradable, biocompatible, safe and effective carriers for drug delivery. Objective:To prepare nanoniosomal silibinin and evaluate its cytotoxicity inthe T-47D breast cancer cell line. Materials and Methods: Niosomes were prepared by reverse phase evaporation of a mixture of span 20, silibinin, PEG-2000 and cholesterol in chloroform and methanol solvent (1:2 v/v). The solvent phase was evaporated using a rotary evaporator and the remaining gel phase was hydrated in phosphate buffer saline. Mean size, size distribution and zeta potential of niosomes were measured with a Zetasizer instrument and then nanoparticles underwent scanning electron microscopy. The drug releasing pattern was evaluated by dialysis and the cytotoxicity of nanoniosomes in T-47D cells was assessed by MTT assay. Results: Particle size, size variation and zeta potential of the niosomal nanoparticles were measured as $178.4{\pm}5.4nm$, $0.38{\pm}0.09$ and $-15.3{\pm}1.3mV$, respectively. The amount of encapsulated drug and the level of drug loading were determined $98.6{\pm}2.7%$ and $22.3{\pm}1.8%$, respectively; released drug was estimated about $18.6{\pm}2.5%$ after 37 hours. The cytotoxic effects of nanoniosome were significantly increased when compared with the free drug. Conclusions: This study finding suggests that silibinin nanoniosomes could serve as a new drug formulation for breast cancer therapy.

• Korean Chemical Engineering Research
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• 제46권3호
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• pp.443-450
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• 2008

고유가 대응방안으로 저등급 석탄의 효과적인 활용기술에 대해 고찰하였다. 현재 산업체에서 사용하는 석탄 중에 갈탄과 아역청탄이 저등급 석탄에 속하며 매장량이 풍부하고 세계적으로 고르게 분포되어 있지만 높은 수분 함량과 자연발화 가능성으로 인해 활용이 많이 되지 않고 있다. 본 논문에서는 저등급 석탄으로부터 화학적 정제기술을 이용하여 초청정석탄을 제조하는 기술에 대하여 고찰하였다. 회분 제거기술인 UCC 공정과 가연성분 추출기술인 Hyper Coal 공정을 비교하였다. 회분 제거기술인 UCC(Ultra Clean Coal) 공정은 Hyper Coal 공정에 비해 단순하다는 장점이 있지만 생성물의 회분 농도가 0.1% 이상으로 높다. 가연성분 추출 기술인 Hyper Coal 공정은 용매추출과 이온제거공정 등 구성은 복잡하지만 회분이 200ppm 이하로 생성된다. 초청정석탄은 오일과 동일 등급의 초 청정연료로써 산업용 석유를 대체하고 장기적으로는 IGCC와 IGFC, 그리고 차세대 고도연소기술의 연료로 활용될 수 있을 것이다.

• 한국토양비료학회지
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• 제48권3호
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• pp.180-188
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• 2015

To investigate the tendency of $Li^+$ exchange from polar organic solvents, $Li^+$-ion exchange into zeolite Y (Si/Al = 1.56) was attempted by undried methanol (crystal 1) and formamide (crystal 2) solvent. Two single crystals of Na-Y were treated with 0.1 M LiNO3 in each of the two solvents at 323 K, followed by vacuum dehydration at 723 K. Their structures were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $Fd{\bar{3}}m$, at 100(1) K. In both structures, $Li^+$ for $Na^+$ ions filled preferentially sites I' and II. The remaining $Na^+$ ions occupied sites I', II, and III' in both structures, in additional to above sites, and $Na^+$ ions occupied site I in crystal 2. While the 68 % exchange of $Li^+$ for $Na^+$ was achieved from undried methanol, only 40 % exchange was observed from undried formamide, indicating that the undried methanol was more effective than undried formamide as solvent for $Li^+$ exchange under the conditions employed.

• 대한화장품학회:학술대회논문집
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• 대한화장품학회 2003년도 IFSCC Conference Proceeding Book II
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• pp.201-212
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• 2003

The heartwood extract of Artocarpus lakoocha Roxb., which contains a potent tyrosinase inhibitor oxyresveratrol, was evaluated for its melanin-reducing efficacy in both guinea pigs and human volunteers. After 4 week-daily application of the extract dissolved in propylene glycol to the back of guinea pigs, significant reduction in melanin content was detected, with the effect greater than 3% kojic acid and solvent propylene glycol (P < 0.05). The extract was subsequently tested in female volunteers (3 groups of 20 subjects) using a parallel clinical trial with self-control. The first group received the A. lakoocha solution in propylene glycol whereas the second and the third group respectively received 0.25% licorice extract and 3% kojic acid in the same solvent. The subject in each group twice daily applied the test solution on one arm whereas the remaining arm was applied with only propylene glycol (self-control) for 12 weeks. The A. lakoocha extract was found to be the most effective agent, giving the shortest onset of significant whitening after only 4 weeks of application (P < 0.05), followed by 3% kojic acid (8 weeks) and 0.25% licorice extract (10 weeks). The whitening effect also increased with time, with the highest extent observed with A. lakoocha at week 12. The in vitro antityrosinase activity of A. lakoocha extract decreased with time upon storage at room temperature but could be stabilized by a combination of several antioxidants. In conclusion, the heartwood extract of A. lakoocha appeared to have promising potential for use as an effective and economical skin-whitening agent.

• 멤브레인
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• 제14권2호
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• pp.108-116
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• 2004

본 연구에서는 비대칭 polyvinylidene fluoride (PVDF)막을 기질막으로 하여 Pore-filled 이온교환막을 제조하였다. 먼저 다공성 PVDF막의 기공에 80%의 chloromethylate aryl ring을 가지고 있는 poly(vinylbenzyl chloride) (PVBCI)과 1,4- diaminobicyclo［2,2,2］octane (DABCO)을 tetrahydrofuran (THF)와 dimethylforamide (DMF)가 8:2로 혼합된 용액에 녹여서 채워 넣고 겔화시킨 후, 남아 있는 chloromethyl group에 trirnethylamine (TMA, 40 wt% in water)을 이용하여 양이온 암모니움 site를 형성시키면 pore-filled 음이온교환막이 형성된다. 이와 같이 2단계의 제조 방식으로 제조된 pore-filled 막은 크기의 변화가 없으며, 가교도의 조절로써 최종 막의 특성이 간단하게 조절되는 것을 보여주었다. SEM과 AFM의 표면촬영의 결과로부터 기질막의 기공 내에 고분자겔의 존재를 확인하였다. 투과도와 배제율에 많은 영향을 미치는 용매를 조사한 결과 tetrahydrofuran (THF)만을 사용하여 제조한 막보다 THF와 DMF를 함께 사용할 때 더 우수한 막이 제조되었다. 제조된 최종 막의 수투과도 조사결과, 가교도 10% 막의 경우 아주 낮은 압력에서(100 Kpa) 전형적인 한외여과막의 투과도(8∼10 kg/$m^2$hr)를 보여주었으며 배제율 또한 우수한 결과(55∼60%)를 보여주었다. 압력에 대한 pore-filled 이온교환막의 성능을 관찰한 결과 압력이 증가할수록 투과도와 배제율은 함께 증가하였다.