• Bulletin of the Korean Chemical Society
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• 제35권6호
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• pp.1799-1805
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• 2014

In this article, we described about the preparation and electrochemical properties of a flexible energy storage system based on a plastic polyethylene terephthalate (PET) substrate. The PET treated with UV/ozone was fabricated with multilayer films composed of 30 polyaniline (PANi)/graphene oxide (GO) bilayers using layer-by-layer assembly of positively charged PANi and negatively charged GO. The conversion of GO to the reduced graphene oxide (RGO) in the multilayer film was achieved using hydroiodic acid vapor at $100^{\circ}C$, whereby PANi structure remained nearly unchanged except a little reduction of doping state. Cyclic voltammetry and charge/discharge curves of 30 PANi/RGO bilayers on PET substrate (shorten to PANi-$RGO_{30}$/PET) exhibited an excellent volumetric capacitance, good cycling stability, and rapid charge/discharge rates despite no use of any metal current collectors. The specific capacitance from charge/discharge curve of the PANi-$RGO_{30}$/PET electrode was found to be $529F/cm^3$ at a current density of $3A/cm^3$, which is one of the best values yet achieved among carbon-based materials including conducting polymers. Furthermore, the intrinsic electrical resistance of the PANi-$RGO_{30}$/PET electrodes varied within 20% range during 200 bending cycles at a fixed bend radius of 2.2 mm, indicating the increase in their flexibility by a factor of 225 compared with the ITO/PET electrode.

• 한국전기전자재료학회논문지
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• 제15권10호
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• pp.896-901
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• 2002

The polarization and strain behavior of multilayer ceramic actuators fabricated by tape casting using a PNN-PZT ceramics were investigated in association with electrode size and internal layer number. Spontaneous polarization and strain decreased with increasing electrode size. In addition, the increase of internal layer number brought reduced spontaneous polarization and increased the field-induced strain. Because the actuators structure is designed to stack ceramic layer and electrode layer alternatively, the ceramic-electrode interfaces may act as a resistance to motion of domain wall. To analyze the effect of ceramic-electrode interface, the diffraction intensity ratio of (002) to (200) planes was calculated from X-ray diffraction patterns of samples subjected to a voltage of 200 V. The diffraction intensity ratio of (002) to (200) planes was decreased with increasing electrode size and internal layer number. The diffraction intensity ratio and straining behavior analyses indicate that the Polarization and strain were affected by the amount of 90°domain decreasing with increasing electrode size and internal layer number. Consequently, the change of polarization and displacement with respect to electrode size and layer number is likely to be caused by readiness of the domain wall movement around the interface.

• Carbon letters
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• 제10권4호
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• pp.325-328
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• 2009

This cycloaddition of [70]fullerene with methyl azidoacetate in benzene under ultrasonic irradiated condition afforded the closed [5,6]-bridged aziridino[70]fullerene derivative, which was unusual product of cycloaddition to the 5,6-junction of fullerene. Its structure was determined by FAB-MS, UV-vis, $^1H-$ and $^{13}C$-NMR spectral data. The closed [5,6]-bridged aziridino[70]fullerene-functionalized gold nanoparticle films were self-assembled using the layer-by-layer method on the reactive of glass slides functionalized with 3-mercaptopropyl trimethoxysilane. The functionalized glass slides were alternately soaked in the solution containing closed the [5,6]-bridged aziridino[70]fullerene and 4-aminothiophenoxide/hexanethiolate-protected gold nanoparticles. The closed [5,6]-bridged aziridino[70]fullerene-functionalized gold nanoparticle films have grown up to 5 layers depending on the immersion time. The self-assembled nanoparticle multilayer films were characterized using UV-vis spectroscopy showed that the surface plasmon band of gold at 527 nm gradually became more evident as successive layers were added to the films.

• 한국정밀공학회지
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• 제27권3호
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• pp.9-17
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• 2010

The FPCB is used for electronic products such as LCD display. The process of manufacturing FPCB includes a cutting process, in which each single FPCB is cut and separated from the panel where a series of FPCBs are arrayed. The most-widely used cutting method is the mechanical punching, which has the problem of creating burrs and cracks. In this paper, the cutting characteristics of the FPCB have been experimented using Nd:YAG DPSS UV laser as a way of solving this problem. To maximize the industrial application of this laser cutting process, test samples of the multilayered FPCB have been chosen as it is actually needed in industry. The cutting area of the FPCB has four different types of layer structure. First, to cut the test sample, the threshold laser cut-off fluence has been found. Various combinations of laser and process parameters have been made to supply the acquired laser cut-off fluence. The cutting characteristics in terms of the variation of the parameters are analyzed. The laser and process parameters are optimized, in order to maximize the cutting speed and to reach the best quality of the cutting area. The laser system for the process automation has been also developed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1588-1593
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• 2008

This paper describes a real-time isometric pinch force prediction algorithm from surface electromyogram (sEMG) using multilayer perceptron (MLP) for human robot interactive applications. The activities of seven muscles which are observable from surface electrodes and also related to the movements of the thumb and index finger joints were recorded during pinch force experiments. For the successful implementation of the real-time prediction algorithm, an off-line analysis was performed using the recorded activities. Four muscles were selected for the force prediction by using the Fisher linear discriminant analysis among seven muscles, and the four muscle activities provided effective information for mapping sEMG to the pinch force. The MLP structure was designed to make training efficient and to avoid both under- and over-fitting problems. The pinch force prediction algorithm was tested on five volunteers and the results were evaluated using two criteria: normalized root mean squared error (NRMSE) and correlation (CORR). The training time for the subjects was only 2 min 29 sec, but the prediction results were successful with NRMSE = 0.112 ${\pm}$ 0.082 and CORR = 0.932 ${\pm}$ 0.058. These results imply that the proposed algorithm is useful to measure the produced pinch force without force sensors in real-time. The possible applications include controlling bionic finger robot systems to overcome finger paralysis or amputation.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.515-520
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• 2004

We report on the development of a Piezoelectric valvc that is designed to have a high reliability for fluid control systems, such as mass flow control, transportation and chemical analysis. The valve was fabricated using a MCA(multilayer ceramic actuator), which has a low consumption power, high resolution and accurate control. The fabricated valve is composed of MCA, a valve actuator die and an seat die. The design of the actuator dic was done by FEM(finite element method) modeling, respectively. And, the valve seat die with 6 trenches was made. and the actuator die, which possible to optimize control to MCA, was fabricated. After Si-wafer direct bonding between the seat die and the actuator die, MCA was also anodic bonded to the scat/actuator die structure. PDMS(poly dimethylsiloxane) sealing pad was fabricated to minimize a leak-rate. It was also bonded to scat die and stainless steel package. The flow rate was 9.13 sccm at a supplied voltage of 100 V with a 50 % duty ratio and non-linearity was 2.24 % FS. From these results, the fabricated MCA valve is suitable for a variety of flow control equipments, a medical bio-system, semiconductor fabrication process, automobile and air transportation industry with low cost, batch recess and mass production.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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• pp.41-41
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• 1998

Rare earth metal films have been used as a buffer layer for growing ferroelectric t thin film or a seed layer for magnetic multilayer. But when it was deposited on s semiconductor substrates for the application of magneto-optic (MO) storage media, it i is difficult to exactly measure magnetic cons떠nts due to shunting current, and so it n needs to grow metal films on insulator substrate to reduce such effect. Recently, it w was reported that ultra-thin Pt layer were epitaxially grown on A12O:J by ion beam s sputtering in 비떠 high vacuum and it can be used as a seed layer for the growth of C Co-contained magnetic multilayer. In this stu$\phi$, Pt thin film were epi떠xially grown on AI2D3 ($\alpha$)OJ) by RF magnetron s sputtering. The crystalline structure was analyzed by transmission electron microscope ( (TEM) and Rutherford Back Scattering (RBS)/Ion Channeling. In TEM study, Pt was b believed to be twinned on AI잉3($\alpha$)01) su$\pi$ace about Pt(ll1) plane.Moreover, RBS c channeling spectra showed that minimum scattering yield of Pt(111)/AI2O:J(1$\alpha$)OJ) was 4 4% and Pt(11J)/AI2D3($\alpha$)OJ) had 3-fold symmetry.

• 열처리공학회지
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• 제23권5호
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• pp.245-248
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• 2010

Sn doped $In_2O_3$ (ITO) and ITO/Ni/ITO (INI) multilayer films were deposited on the glass substrates with a reactive magnetron sputtering system without intentional substrate heating and then the influence of the Ni interlayer on the methanol gas sensitivity of ITO and INI film sensors were investigated. Although both ITO and INI film sensors have the same thickness of 100 nm, INI sensors have a sandwich structure of ITO 50 nm/Ni 5 nm/ITO 45 nm. The changes in the gas sensitivity of the film sensors caused by methanol gas ranging from 100 to 1000 ppm were measured. It is observed that the INI film sensors show the higher sensitivity than that of the ITO single layer sensors. Finally, it can be concluded that the INI film sensor have the potential to be used as improved methanol gas sensors.

• 한국자기학회지
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• 제4권4호
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• pp.307-312
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• 1994

(Fe, Co)/(Pd, Pt, Cu, Ag)로 이루어진 금속 다층박막에 대한 자기광학 Kerr 효과(${\theta}_{k}$) 스펙트럼을 박막내에서 빛의 다중간섭 이론을 적용하여 계산하였고, 그 결과를 보고된 실험값과 비교하였다. Co/Pd 다층막의 경우, ${\theta}_{k}$ 스펙트럼의 조성에 따른 파장 의존성에 대한 계산값이 서로 잘 일치하였으며, Fe/Cu 및 Fe/Ag 다층막에 있어서는 Cu와 Ag의 광흡수단 영역에서 다층막 고유의 새로운 peak가 나타나는 실험현상을 계산결과로 설명이 가능하였다. 그러나 Co/Pt 다층막의 경우에는 실험으로 측정된 300 nm파장 영역에서의 거대한 자기 광학 효과를 다중간섭이론으로는 설명할 수 없었으며, 이는 Co 또는 Pt 고유의 광학정수가 다층막을 이루면서 변화되어 나타나는 현상으로 생각된다.

• 전자공학회논문지B
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• 제33B권8호
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• pp.105-113
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• 1996

In this paper, a new korean digita speech recognition technique was proposed using muktolayer perceptron (MLP). In spite of its weakness in dynamic signal recognition, MLP was adapted for this model, cecause korean syllable could give static features. It is so simle in its structure and fast in its computing that MLP was used to the suggested system. MLP's input vectors was transformed using karhunen-loeve transformation (KLT), which compress signal successfully without losin gits separateness, but its physical properties is changed. Because the suggested technique could extract static features while it is not affected from the changes of syllable lengths, it is effectively useful for korean numeric recognition system. Without decreasing classification rates, we can save the time and memory size for computation using KLT. The proposed feature extraction technique extracts same size of features form the tow same parts, front and end of a syllable. This technique makes frames, where features are extracted, using unique size of windows. It could be applied for continuous speech recognition that was not easy for the normal neural network recognition system.