• Applied Science and Convergence Technology
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• v.23 no.4
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• pp.161-168
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• 2014

A real-time monitoring of immersed antenna type inductively coupled plasma (ICP) was done with a homemade 2 dimensional voltage probe array to check the uniformity of the plasma. Measured voltage values with a high impedance voltmeter are close to the floating potential of the plasma. As the substrate carrier was moving into a magnetron sputtering plasma diffusive from a $125mm{\times}625mm$ size cathode, measured results showed reliably separation of plasma into the upper and lower empty space over the carrier. Infra red thermal imaging camera was used to observe the cross corner effect in situ without eroding a target to the end of the usage. 3 dimensional particle trace model was used to analyze the magnetron discharge's behavior.

• Journal of Magnetics
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• v.13 no.4
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• pp.177-181
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• 2008

A very simple a.c. magnetic susceptometer for use in a helium closed cycle cryostat is reported in this paper. This simple setup has only a single bobbin-less copper coil, instead of the primary coil and two secondary coils typically used in mutual-inductance types. The single bobbin-less copper coil is directly mounted on the cryostat cold head. A sample is attached on the inside wall of the copper coil using a thermal contact material and its a.c. magnetic susceptibility is obtained from the measurement of the self-inductance of the sample coil using an LCR meter or an impedance analyzer. Experimental details are described and illustrative measurements on magnetic and superconducting materials as a function of temperature are included. The performances and limitations of this simple a.c. magnetic suceptometer are also discussed.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.05a
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• pp.134-138
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• 2005

Recently many researches related with biotechnology are processed and it is the situation that research about micro fluidic devices is active. Micro fluidic devices has been one of the most widely used devices for the analysis in biotechnology because they have many advantages, flexibility, transparency, thermal and electrical stability, nontoxic, etc. In this study, micro fluidic device with PDMS is developed for particle counter which separates a small quantity of particles, The principle of micro particle counter is electrical-impedance method, and it was also applied hydrodynamic flow focusing. It is more efficient method to analyzing particles furthermore it can be applied to cell count ins for biotechnology.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.175-175
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• 2013

염료감응형 태양전지(Dye Sensitized Solar Cells; DSSC)에서 투명전극(Transparent Conducting Oxide; TCO)으로 사용되는 ITO, FTO의 경우 자원의 희소성과 고온에 취약하며 취성과 같은 단점 등이 있다. Graphene은 단원자층의 얇은 물질로써 우수한 전도도와 투과도, 고강도와 고탄성의 특성들을 가진다. 이러한 특성들을 가지는 Graphene을 기존의 투명전극을 대체하여 DSSC의 작업전극에 적용 하였다. 본 실험에서 사용된 그래핀 시트는 근적외선을 source로 하는 RTA (Rapid Thermal Annealing)장비에 탄화수소 기반의 gas를 주입하여 Ni위에 성장시켰으며, 습식방법인 용액Etching 방식을 사용하여 유리판 위에 전사시켰다. 전사된 Graphene 투명전극의 전기적 특성과 광학적 특성을 평가하기 위해 4 point probe, FT-IR, 마이크로 Raman분광법, 광학현미경 및 투과도를 측정하여 평가 하였다. 전사된 Graphene 투명전극을 염료감응형 태양전지 작업전극에 적용하여, DSSC소자를 제작하고, Solar Simulator로 광전변환효율 및 EIS(Electrochemical Impedance Spectroscopy)를 측정하여 기존의 FTO로 만든 DSSC와 비교하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.540-543
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• 2000

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. The temperature dependence of conductivity, impedance spectroscopy and electrochemical properties of PAN/PVDF electrolytes as a function of a mixed ratio were reported for PAN/PVDF based polymer electrolyte films, which were prepared by thermal gellification method of preweighed PAN/PVDF, plasticizer and Li salt. The conductivity of PAN/PVDF electrolytes was $10^{-3}$S/cm. $PAN_{10}$$PVDF_{10}$$LiClO_4$$PC_{5}$$EC_{5}$ electrolyte has the better conductivity compared to others. The interfacial resistance behavior between the lithium electrode and PAN/PVDF based polymer electrolyte has also been investigated and compare with that between the lithium electrode and the PAN/PVDF based polymer electrolyte.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1704-1705
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• 2007

A step-down procedure employing low voltage thermal transfer standard(LVTS) and micropotentiometer is described for the establishing the ac low voltage standards in the range of 2 mV to 200 mV below 1 MHz. Techniques are given for measuring input impedance with insertion method and calculating the loading error for the ac-dc transfer difference of the LVTS.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.320-320
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• 2010

The dye-sensitized solar cells (DSSCs) have achieved so far the highest validated efficiency over 11%. However, the cells with the best performance utilize volatile solvent as a electrolyte, which can cause some practical limitations for the long-term operation. This is one of the most substantial problems to be resolved for the commercialization of DSSCs. In order to improve the long-term stability, many research groups have reported new electrolyte system, to replace the liquid type electrolyte by non-volatile ones. In this work, we studied long-term stability of the DSSCs with various types of electrolytes such as (PVDF HFP) based polymer, eutectic melts of ionic liquids, and liquid based solvent. The cells with various electrolytes have been exposed to the condition under thermal stress and illumination over 1000 hours. We will report the change of photovoltaic properties with time and investigate the degradation mechanism with the impedance spectroscopic analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.415-420
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• 2000

This paper describes a part of the results obtained in the process of the development of thin sound isolation sheets filled mineral compound powder with PVC. The raw materials used are pyrophillite, pottery stone and graphite. The physical properties such as the crystal structures, compositions, and specific gravities, etc. of raw materials are analyzed and discussed from a point of view of sound isolation material. From the analysis of experimental results, the particle size and the additive amount of mineral compound powder for manufacturing sample isolation sheets are decided. The resistant capability against fire of sound isolation sheets including mechanical, thermal and physical properties is tested. The transmission loss measuremenst of sound isolation sheets are performed using two-microphone method in an impedance tube. It is shown that the sound isolation capability of thin sheets has an excellent performance in excess of the object of development.

• Archives of Metallurgy and Materials
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• v.63 no.3
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• pp.1497-1502
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• 2018

Macroporous silica fibers having spherical cavities were fabricated by electrospinning using the spinning solution prepared from the mixed dispersion of tetraethylorthosilicate (TEOS) and polystyrene nanospheres as precursor and sacrificial templates, respectively, by injection through metallic nozzle. By applying electric field, the electro-spun fibers obtained by evaporation-driven self-assembly were collected on flat substrate or rotating drum, followed by the removal of the templates by calcination. The sound absorption coefficient of the porous fibers was measured by impedance tube, and the measured value was larger than 0.9 at high frequency region of incident waves. The surface of the resulting fibers was modified using fluorine-containing silane coupling agent to produce superhydrophobic fibrous materials to prevent the infiltration of humidity.

• Applied Microscopy
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• v.47 no.3
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• pp.131-147
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• 2017

In this work further optical and electrical investigations of pure and Zr doped $Mn_3O_4$ (from 0 up to 20 at.%) thin films as a function of frequency. First, the refractive index, the extinction coefficient and the dielectric constants in terms of Zr content are reached from transmittance and reflectance data. The dispersion of the refractive index is discussed by means of Cauchy model and Wemple and DiDomenico single oscillator models. By exploiting these results, it was possible to estimate the plasma pulse ${\omega}_p$, the relaxation time ${\tau}$ and the dielectric constant ${\varepsilon}_{\infty}$. Second, we have performed original ac and dc conductivity studies inspired from Jonscher model and Arrhenius law. These studies helped establishing significant correlation between temperature, activation energy and Zr content. From the spectroscopy impedance analysis, we investigated the frequency relaxation phenomenon and hopping mechanisms of such thin films. Moreover, a special emphasis has been putted on the effect of the oxidation in air of hausmannite thin films to form $Mn_2O_3$ ones at $350^{\circ}C$. This intrigue phenomenon which occurred at such temperature is discussed along with this electrical study. Finally, all results have been discussed in terms of the thermal activation energies which were determined with two methods for both undoped and Zr doped $Mn_3O_4$ thin films in two temperature ranges.