• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1594-1596
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• 2004

Film bulk acoustic resonator (FBAR) devices which adopt a membrane-type configuration are fabricated by a novel process. In contrast to the conventional FBAR structure, the newly fabricated resonator doesn't employ any supporting layer below or above it, so that the properties of piezoelectric layer are not influenced by the bottom electrode material. FBAR devices with Mo/AlN/Metal configuration are also fabricated. The frequency response characteristics ($S_{11}$) of the devices fabricated using the proposed process are compared with those of the conventional devices. The return losses are also estimated, in terms of the kind and thickness of bottom electrode materials.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1968-1972
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• 2010

Pt-Co alloy nanowire array was directly synthesized by electrochemical deposition with polycarbonate template at -1.0V and subsequent chemical etching of the template. The use of Pt-Co alloy nanowire array-modified electrode (Pt-Co NAE) for the determination of morphine (MO) is described. The morphology of the Pt-Co alloy nanowire array has been investigated by scanning electron microscopy (SEM) and energy disperse X-ray spectroscopy (EDS) analysis), respectively. The resulting Pt-Co NAE offered a linear amperometric response for morphine ranging from $2.35\times10^{-5}$ to $2.39\times10^{-3}$ M with a detection limit of $7.83\times10^{-6}$ M at optimum conditions. This sensor displayed high sensitivity and long-term stability.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.276.2-276.2
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• 2016

Dye-sensitized solar cells (DSCs) are promising candidates for light-to-energy conversion devices due to their low-cost, easy fabrication and relative high conversion efficiency. An important component of DSCs is counter electrode (CE) collect electrons from external circuit and reduct I3- to I-. The conventional CEs are thermally decomposed Pt on fluorine-doped tin oxide (FTO) glass substrates, which have shown excellent performance and stability. However, Pt is not suitable in terms of cost effect. In this report, we demonstrated that nickel sulfide thin films by atomic layer deposition (ALD)-using Nickel(1-dimethylamino-2-methyl-2-butanolate)2 and hydrogen sulfide at low temperatures of $90-200^{\circ}C$-could be good CEs in DSCs. Notably, ALD allows the thin films to grow with good reproducibility, precise thickness control and excellent conformality at the angstrom or monolayer level. The nickel sulfide films were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction, hall measurements and cyclic voltammetry. The ALD grown nickel sulfide thin films showed high catalytic activity for the reduction of I3- to I- in DSC. The DSCs with the ALD-grown nickel sulfide thin films as CEs showed the solar cell efficiency of 7.12% which is comparable to that of the DSC with conventional Pt coated counter electrode (7.63%).

• Journal of the Korean institute of surface engineering
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• v.28 no.1
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• pp.34-45
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• 1995

An amphiphilic nitroxide radical(2,2'6,6'-tetramethyl-4-octadecyioxy-1-piperidinyloxyl, TEMOPO) or mixture of TEMOPO and arachidic acid(Icosanoic acid, AA), was spread on water surface by the Langmuir-Blodgett(LB) method and surface pressure-area curve was measured. Such monolayer films of TEMOPO were transferred onto surfaces of photo transferable tin oxide electrodes(PTTO) by the LB method under various surface pressure with the transfer ratio of larger than 0.95 at the surface pressure higher than 15mN/m. The electrochemical effect of functional nitroxy radical monolayer onto semi-conductive electrode to electrolyte have been investigated by using LB method. Cyclic voltammetry technique was used for the electrochemical behavior measurement of TEMOPO monolayer onto the PTTO in 0.18 mo1/$dm^3$ $H_2SO_4$ solutions. The shape of voltammograms was found to change from one electrode to another. The amount of charge for the oxidation and the re-reduction of the cation to TEMOPO were evaluated from graphical integration. The amounts of charge were always smaller than those predicted from the $\pi$-$\sigma$ curves though the transfer ratio was unity. The poor reproducibility of the cyclic voltammograms was improved by the mixing with AA. Structure and arrangement of monomolecular layer on water surface and electrode were studied. Characteristics of monolayer film applied for the mediation reaction was also discussed by electrochemical method.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2811-2816
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• 2007

We conducted a numerical study of AC-electroosmotic (alternating current) effect on the fluid flow and mixing in a 3-D microchannel. The microchannel used as an efficient micro-mixer is composed of a channel and a series of pairs of electrodes attached in zigzag pattern on the bottom wall. The AC electric field is applied to the electrodes so that a steady flow current takes place around the electrodes. This current is flowing across the channel and thus contributing to the mixing of the fluid within the channel. We performed numerical simulations by using a commercial code to obtain a steady flow field. This steady flow is then used in evaluation of the mixing performance via the concept of mixing index. It was found that good combination of two kinds of electrode, which gave us a good mixing, is not simple harmonic. And when the length ratio of these two kinds of electrode is 2:1, we can get the best mixing effect.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.792-796
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• 2000

With the development of micro machining, it becomes an important part to fabricate an electrode which has tens of ${\mu}m$ or less. There are two methods to get a narrow hole; non-contact type such as EDM(Electro-discharge machining) and contact type such as punching. A punch which has a tapered shape with a cylindrical tip is fabricated in this paper. To make this punch, a method which was used to fabricate a cylindrical shape by electrochemical process was applied. The control factors for the shape and their limits are verified through an experiment.

• Journal of Sensor Science and Technology
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• v.17 no.4
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• pp.281-288
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• 2008

Polyacrylonitrile(PAN)/metal oxide(MO) nanocomposite mats with a thickness of 0.12 mm were electrospun by adding 0 to 10 wt% of MO nanoparticles ($Fe_2O_3$, ZnO, $SnO_2$, $Sb_2O_3-SnO_2$) into PAN. Pt electrode was patterned on $Al_2O_3$ substrate by DC sputtering and then the PAN(/MO) mats on the Pt patterned $Al_2O_3$ were electrically wired to investigate the $CO_2$ gas sensing properties. As the MO content rose, the fiber diameter decreased due to the presence of lumps caused by the presence of MOs in the fiber. The PAN/2% ZnO mat revealed a faster response time of 93 s and a relatively short recovery of 54 s with a ${\Delta}R$ of 0.031 M${\Omega}$ at a $CO_2$ concentration of 200 ppm. The difference in sensitivity was not observed significantly for the PAN/MO fiber mats in the $CO_2$ concentration range of 100 to 500 ppm. It can be concluded that an appropriate amount of MO nanoparticles in the PAN backbone leads to improvement of the $CO_2$ gas sensing properties.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.263-266
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• 2000

This paper is focused on the fabrication of reliable Al/$TiO_2-SiO_2$/Mo antifuse, which could operate at low voltage along with the improvement in on/off state properties. Mo metal as the bottom electrode had smooth surface and high melting point, and was being kept as-deposited $SiO_2$film stable. The breakdown voltage of TiO_2-SiO_2$ stacked antifuse was better than that of same-thickness (100 $\AA$) $SiO_2$antifuse because of Ti diffusion in $SiO_2$. The improving breakdown-voltage and on-resistance can be obtained as well as the influence of hillock in the bottom metal is reduced by using double insulator. Low on-resistance (65 $\Omega$) and low programming voltage (9.0 V) can be obtained in these antifuses with 250 $\AA$ double insulator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.169-172
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• 2004

최근 LCD 노트북 제품의 고유한 특정인 경박단소가 요구되면서, 백라이트의 박형화로 인해 광원으로써 램프의 세경화에 대한 개발도 진행되고 있다. 특히, 노트북용 램프의 경우 발열이 심해 도광판을 비롯한 시트류의 주름현상이 발생하며, 수명연장을 위해서 전극의 표면적이 넓거나 일함수(work functuon)가 작은 재질의 개발이 필요하다. 따라서 노트북용으로 저발열, 장수명을 위한 램프를 개발하고 있으며, 본 연구에서도 기존 Ni 전극을 사용한 램프 대비 Nb, Mo, Ta 전극을 사용했을때 통일한 구동조건에서 103%의 휘도특성 개선을 확인할 수 있었고 수명면에서도 기존 Ni 전극 대비 일함수가 낮은 Nb, Mo, Ta 전극을 사용한 램프의 경우 시간경과에 따른 휘도저하가 낮은 것으로 나타났다.

• Tribology and Lubricants
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• v.27 no.2
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• pp.88-94
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• 2011

The tribological characteristics of the swash plate surface of a compressor which is for automobile were investigated. For surface treatments, PTFE and $MoS_2$ are used as a solid lubricant, together with copper alloy. Test condition is set considering actual driving condition. Wear testing is conducted using pin on disk type tester, and the coefficient of friction and the temperature on friction surface are measured. Also, to determine the wear patterns, cross-section of friction surface is analyzed by SEM(scanning electrode microscope). The $MoS_2$, both at dry and lubricated conditions, friction surface and the coefficient of friction maintained rather stable results. But, the PTFE, at oil less condition, sample resulted in rather unstable condition. In case of copper alloy, quite higher friction coefficients(higher than 0.1) were obtained at dry condition. At the temperature of $125^{\circ}C$, seizure has occurred.