• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.207-207
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• 2013

기존의 그래핀 성장에 관한 연구는 열화학기상증착법(Chemical vapor deposition; CVD)을 이용한다. 그래핀 성장 제어 요소로는 촉매 기판인 전이 금속[Ru, Ir, Co, Re, Pt, Pd, Ni, Cu], 기판 전처리 과정, 수소/메탄 가스 혼합비, 작업 진공 상태, 기판온도[$800{\sim}1,000^{\circ}C$, 냉각 속도 등으로 보고 되고 있다. 그래핀 성장 원리는 Cu 촉매 기판에 메탄 가스를 $1,000^{\circ}C$ 온도에서 분해해서 탄소를 고용 시킨 후 급랭하는 도중에 석출되는 탄소에 의해 그래핀 시트가 형성되는 것으로 알려져 있다. 기존의 CVD를 열원을 이용할 경우 내부 챔버에 생기는 잠열에 의해 cooling profile의 제어가 용이하지 않다. 본 연구에서는 근적외선(Near Infrared; NIR) 열원을 이용한 CVD로 챔버 내부 잠열을 최소화하고, 냉각 공정을 Natural, Linear, Convex cooling type으로 디자인해서 cooling profile 제어가 그래핀 성장에 미치는 영향을 연구 하였다. 이렇게 성장된 그래핀을 임의의 기판(SiO2, Glass, PET film) 위에 습식방법으로 전이 시킨 후, 전기적 구조적 및 광학적 특성을 면저항(four-point probe), 전계방사 주사전자현미경(Field Emission Scanning Electron Microscope; FE-SEM), 마이크로 라만 분광법(Micro Raman spectroscopy) 및 광학현미경(optical microscope), 투과도(UV/Vis spectrometer)의 측정으로 잠열이 최소화된 NIR-CVD에서 cooling profile에 따른 그래핀 성장을 평가하였다.

• Transactions on Electrical and Electronic Materials
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• 제12권6호
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• pp.258-261
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• 2011

A ferroelectric $(Bi,La)_4Ti_3O_{12}$ (BLT) thin film fabricated by the pulsed-DC sputtering method was evaluated on a cell structure to check its compatibility to high density ferroelectric random access memory (FeRAM) devices. The BLT composition in the sputtering target was $Bi_{4.8}La_{1.0}Ti_{3.0}O_{12}$. Firstly, a BLT film was deposited on a buried Pt/$IrO_x$/Ir bottom electrode stack with W-plug connected to the transistor in a lower place. Then, the film was finally crystallized at $700^{\circ}C$ for 30 seconds in oxygen ambient. The annealed BLT layer was found to have randomly oriented and small ellipsoidal-shaped grains (long direction: ~100 nm, short direction: ~20 nm). The small and uniform-sized grains with random orientations were considered to be suitable for high density FeRAM devices.

• Biomolecules & Therapeutics
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• 제5권2호
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• pp.125-132
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• 1997

Cisplatin, a platinum-complex, is currently one of the most effective compounds used in the treat-ment of solid tumors. However, its use is limited by severe side effects such as renal toxicity. Our platinum-based drug discovery program is aimed at developing drugs capable of diminishing toxicity and improving selective cytotoxicity. We synthesized new Pt (II) complex analogue containing 1,2-diaminocyclohexane (DACH) as carrier ligand and 1,2-bis (diphenylphosphino) ethane (DPPE) as a leaving group. Furthermore, nitrate was added to improve the solubility. A new series of [Pt(cia-DACH)(DPPE)] . $2NO_3$ (PC) was synthes-ized and characterized by their elemental analysis and by various spectroscopic techniques [infrared (IR), $_{13}$carbon nuclear magnetic resonance (NMR)] .PC demonstrated acceptable and significant antitumor activity against SKOV-3 and OVCAR-3 human ovarian carcinoma cell lines as compared with that of cisplatin. The cytotoxicity of PC in normal cells was found quite less than that of cisplatin using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), ($^3$H)thymidine uptake and glucose consumption tests in rabbit renal proximal tubular cells, human renal cortical cells and tissues. In conclusion, PC is considered to be more selective cytotoxicity toward human ovarian cancer cells than normal human/rabbit kidney cells.

• Rapid Communication in Photoscience
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• 제3권3호
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• pp.42-47
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• 2014

Development of molecular and supramolecular systems showing efficient photoinduced energy or electron transfer are of current research interest due to their applications in various chemical and biological processes. Various polypyridine metal complexes including Ru(II), Ru(III), Os(II), Pt(II), Fe(II), Re(I), Ir(III) and so on as a metal center introduce for expanding some more understanding of molecular-scale photoelectronics. Their complexes are concisely classified by the types of relay ligands as follows; (a) metal-direct ligand-metal system; dinuclear or trinuclear systems, (b) metal-nonconjugated ligand-metal system and metal-nonconjugated ligand system having flexible/rigid ligand, (c) metal-conjugated ligand-metal system, and (d) conjugated ligand-metal-conjugated ligand system and metal-self assembly ligand-metal system. It is pointed out that the role played by the relay ligands is important in constructing the metal complexes.

• 한국환경과학회지
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• 제16권9호
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• pp.1085-1090
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• 2007

The performance of EF (electroflotation) on the thickening of activated sludge were investigated using laboratory scale batch flotation reactor. In this paper, the effects of parameters such as electrode material, NaCl dosage, initial sludge concentration and electrode distance were examined. The results showed that the performance for sludge thickening of the five electrodes lay in: Pt/Ti > Ru/Ti > Ir/Ti > Ti mesh > Ti plate. The more NaCl dosage was high, the more sludge was thickened and the shorter thickening time was obtained. However, considering the final thickening time and sludge concentration, optimum NaCl dosage was 0.5 g/L. Thickening time and sludge concentration was not affected by electrode distance. In DAF (dissolved air flotation) system, optimum recycle ratio was 40% and thickening performance was lower than that of the EF.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 추계학술발표대회 개요집
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• pp.45-48
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• 2003

Over the past few decades, there has been increasing research and commercial activity in invasive and non-invasive biomedical technology. One important challenge to developing these devices involves the increasing density of electrical interconnects. Resistance spot welding is limited in the density of interconnect based on either the size of welding head or the positional precision with which a weld can be made. Development of an automated laser microwelding system would permit the continued advancement of these important biomedical technologies. The objective of this work is to demonstrate the application of pseudo-pulse Nd:YAG laser technology as an alternative to resistance spot welding in performing electrical interconnection within biomedical products. To date, some experiments have been conducted by using a pseudo-pulse 1064 nm Nd:YAG laser, a successful weld of a 25 ${\mu}{\textrm}{m}$ diameter Pt/Ir wire to a 316 stainless steel shim can be made. Another application involves welding clips, which may be used for external interconnection, to electrodeposited nickel domes that make particular interconnections to specific insulated wires within a cable. These results show a great deal of promise for developing such a process.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.72-73
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• 1998

A new method for enzyme immobilization has been developed to remove interference by potential interferents in body fluids. Instead of using electron mediators, we chose direct hydrogen peroxide measurement route. Extremely hydrogen peroxide-selective polymer was coated as an inner membrane to exclude interferents and then glucose oxidase(GOx) was entrapped by electropolymerization of inert monomers. There was no solvent casting step throughout the whole fabrication procedure but all membranes on Pt-Ir electrode were formed by electropolymerization. Thus, membrane thickness, quantity of enzyme loaded and can be controlled by electrochemical parameters. As a result, reproducibility of biosensor characteristics becomes remarkably improved in terms of mass production.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.235-238
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• 2009

To study the relationship between spark ignition and the gap in the nano-scale region, the electric potential was applied to between a Pt-Ir tip and a gold substrate. The tip was sharpened by electro-chemical etching process in the solution of $CaCl_2;H_2O$ and acetone. The radius of tip was measured to be around 200nm and attached to the scanning probe microscope to control the gap between the tip and the substrate. The electric potential of 10V to 80V was applied to initialize the spark. The gaps and the current profile were measured to analyze the characteristics of spark ignition. A spark sustaining time was measured to be between 50ns and 200ns depending on the applied electric potential and the gap between the electrodes. The continuous electric discharge was successfully sustained up to 1 second of spark or arc time. The developed process can be applicable to the micro-scale fabrication of automotive sensors as a similar concept of GTAW.

• 한국광물학회지
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• 제12권2호
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• pp.77-90
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• 1999

Characteristics and variations of chemical compositions in Co-rich crusts occurred in the EEZ of the Republic of Marshall Islands were reviewed. Correlation coefficient analysis, hierarchical cluster analysis, and Q-mode factor analysis for 62 samples were done in this study. All data were selected and gathered from the open file report of the cooperative cruise done by United States Geological Survey with Scripps Institute of Oceanography, University of Hawaii or Korea Ocean Research Development Institute. The average of crust thickness. Co content, and Ni content of 62 samples from the 21 seamounts were 30mm, 0.58 wt% and 0.40%, respectively. The mineral phases and associated elements assigned by correlation coefficients, cluster analysis and Q-mode factor analysis are following four. 1) CFA: P, Ca, CO2, Y, Sr: 2) Mn-oxide mineral: As, Mn, Co, Na: 3) Al-silicate mineral: Pd,Si, Al, Cu, Fe: 4) PGE-bearing mineral: Rh, Pt, Ir.

• 대한기계학회논문집A
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• 제28권11호
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• pp.1727-1732
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• 2004

A nickel layer was deposited onto the PZT thin films, serving both as a selective radiation absorption layer and as a top electrode. The absorption properties of such nickel coated multi-layered infrared detectors were studied in the visible and infrared wavelength ranges. The optimal thickness of the nickel layer on our substrate was 10nm. The maximum absorption coefficient of the deposited 10nm thick nickel layer was 0.7 at a 632nm wavelength. However, a striking asymmetric polarization hysteresis loop was observed in these PZT thin films with nickel as the top electrode. This asymmetric polarization was attributed to the difference between the dynamic pyroelectric responses in these Ni/PZT/Pt films poled either positively or negatively before the measurement. A positively poled film showed a 40% higher voltage response than a negatively poled detector.