• Nuclear Engineering and Technology
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• 제48권3호
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• pp.608-612
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• 2016

D-(+)-glucose (Glc) was added to the original Fricke polyvinyl alcohol-glutaraldehyde-xylenol orange (FPGX) hydrogel dosimeter system to make a more stable FPGX hydrogel three-dimensional dosimeter in this paper. Polyvinyl alcohol was used as a substrate, which was combined with Fricke solution. Various concentrations of Glc were tested with linear relevant fitting for optimal hydrogel production conditions. The effects of various formulations on the stability and sensitivity of dosimeters were evaluated. The results indicated that D-(+)-Glc, as a free radical scavenger, had a great effect on stabilizing the dose response related to absorbency and reducing the auto-oxidization of ferrous ions. A careful doping with Glc could slow down the color change of the dosimeter before and after radiation without any effect on the sensitivity of the dosimeter.

• 전자공학회논문지A
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• 제32A권3호
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• pp.68-77
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• 1995

Characteristics of electron cyclotron resonance (ECR) plasma thermal oxide grown at low-temperature have been investigated. The effects of several process parameters such as substrate temperature, microwave power, gas flow rate, and process pressure on the growth rate of the oxide have been also investigated. It was found that the plasma density, reactive ion species, is strongly related to the growth rate of ECR plasma oxied. It was also found that the plasma density increases with microwave power while it decreases with decreasing O2 flow rate. The oxidation time dependence of the oxide thichness showed parabolic characteristics. Considering ECR plasma thermal oxidation at low-temperature, the linear as well as parabolic rate constants calculated from fitting data by using the Deal-Grove model was very large in comparison with conventional thermal oxidation. The ECR plasma oxide grown on (100) crystalline-Si wafer exhibited good electrical characteristics which are comparable to those of thermal oxide: fixed oxide charge(N$_{ff}$)= 7${\times}10^{10}cm^{-2}$, interface state density(N$_{it}$)=4${\times}10^[10}cm^{-2}eV^{-1}$, and breakdown field > 8MV/cm.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.560-574
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• 2016

This paper presents a novel method for power system harmonic estimation based on the Park transform. The proposed method firstly extends the signal to a group of three-phase signals in a-b-c coordinate. Then, a linear fitting based method is adopted to estimate the fundamental frequency. Afterwards, the Park transform is utilized to convert the three-phase signals from a-b-c coordinate to d-q-0 coordinate. Finally, the amplitude and phase of a harmonic component of interest can be calculated using the d-axis and q-axis components obtained. Simulation studies have been conducted using matrix laboratory (MATLAB) and power system computer aided design/electromagnetic transients including direct current (PSCAD/EMTDC). Simulation studies in MATLAB have considered three scenarios, i.e., no-frequency-deviation scenario, frequency-deviation scenario and the scenario in the presence of inter-harminics. The results have demonstrated that the proposed method achieves very high accuracy in frequency, phase and amplitude estimation under noisy conditions, and suffers little influence of the inter-harmonics. Moreover, comparison studies have proved that the proposed method is superior to FFT and Interpolated FFT with the Hanning Window (IpFFTHW). Finally, a popular case in PSCAD/EMTDC has been employed to further verify the effectiveness of the proposed method.

• 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.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.310-310
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• 2012

ZnO thin films were grown on porous silicon (PS) by plasma-assisted molecular beam epitaxy (PA-MBE). The optical properties of the ZnO thin films grown on PS were studied using room-temperature, low-temperature, and temperature-dependent photoluminescence (PL). The full width at half maximum (FWHM) of the near-band-edge emission (NBE) from the ZnO thin films was 98 meV, which was much smaller than that of ZnO thin films grown on a Si substrate. This value was even smaller than that of ZnO thin films grown on a sapphire substrate. The Huang-Rhys factor S associated with the free exciton (FX) emission from the ZnO thin films was found to be 0.124. The Eg(0) value obtained from the fitting was 3.37 eV, with ${\alpha}=3.3{\times}10^{-2}eV/K$ and ${\beta}=8.6{\times}10^3K$. The low- and high-temperature activation energies were 9 and 28 meV, respectively. The exciton radiative lifetime of the ZnO thin films showed a non-linear behavior, which was established using a quadratic equation.

• 한국표면공학회지
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• 제50권4호
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• pp.237-243
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• 2017

We demonstrated the thin film deposition of sodium phosphorous oxynitride (NaPON) via RF magnetron sputtering of $Na_3PO_4$, as a solid-state Na-ion conductor similar to lithium phosphorous oxynitride (LiPON), which is a commonly used solid electrolyte. The deposited NaPON thin film was characterized by scanning electron microscopy, X-ray diffractometry, and electrochemical impedance spectroscopy, to investigate the feasibility of the solid-state electrolyte in several different cell configurations. The key properties of a solidstate electrolyte, i.e., ionic conductivity and activation energy, were estimated from the complex non-linear least square fitting of the measured impedance spectra at various temperatures in the range of $27-90^{\circ}C$. The ionic conductivity of the NaPON film was measured to be $8.73{\times}10^{-6}S\;cm^{-1}$ at $27^{\circ}C$, which was comparable to that of the LiPON film. The activation energy was estimated to be 0.164 eV, which was lower than that of the LiPON film (0.672 eV). The obtained values encourage the use of a NaPON thin film in the future as a reasonable solid-state electrolyte.

• 한국응용과학기술학회지
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• 제25권1호
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• pp.52-57
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• 2008

In the present study, impedance characteristics for AgO-Zn cell at various State-of-Charge (SoC) has been studied. The impedance measurements of AgO-Zn cell at various SoC were made over the frequency range from 100kHz to 10mHz with an amplitude 5mV. The impedance parameters have been evaluated by the analysis of the data using an equivalent circuit and a Non-linear least squares (NLLS) fitting method. The total resistances reflects the SoC of the cell. This indicates that the total resistance is important parameter for predicting SoC of AgO-Zn cell.

• Journal of the Korean Data and Information Science Society
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• 제21권2호
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• pp.241-250
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• 2010

원형자료에 대한 모형화 분석은 주로 von Mises 분포를 비롯한 대칭형의 경우를 중심으로 많은 연구가 이루어져 왔다. 최근 선형자료의 분석에서 다양한 비대칭의 자료에 적합한 왜정규분포의 활용에 대한 연구가 활발히 수행되고 있다. 본 논문에서는 Pewsey (2000a)에 의해 처음 소개된 겹친왜정규분포를 이용한 비대칭의 원형자료에 대한 적합을 다루었다. 특히 비대칭 다봉형 원형자료의 적합을 위해 겹친왜정규혼합분포를 제안하고, EM 알고리즘을 통한 모수추정 과정을 제시하였다. 모의실험을 통해 EM 알고리즘을 통한 모수추정의 정확성을 확인하고, 실제 지방국도의 일일교통량 자료의 모형화 분석에 적용하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.927-930
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• 2000

Visual features of lip area play an important role in the visual speech information. We are concerned about correct lip area as region of interest (ROI). In this paper, we propose a robust and fast method for locating the mouth corners. Also, we define a region of interest at mouth during speech. A method, which we have used, only uses the horizontal and vertical image operators at mouth area. This searching is performed by fitting the ROI-template to image with illumination control. Most of the lip extraction algorithms are dependent on luminosity of image. We just used the binary image where the variable threshold is applied. The variable threshold varies to illumination condition. In order to control those variations, the gray-tone is converted to binary image by threshold, which is obtained through Multiple Linear Regression Analysis (MLRA) about divided 2D special region. Thus we obtained the region of interest at mouth area, which is the robust extraction about illumination. A region of interest is automatically extracted.

• Structural Engineering and Mechanics
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• 제39권1호
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• pp.77-91
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• 2011

A simply structural damage detection software is developed to identification damage in beams. According to linear fracture mechanics theory, the localized additional flexibility in damage vicinity can be represented by a lumped parameter element. The damaged beam is modeled by wavelet-based elements to gain the first three frequencies precisely. The first three frequencies influencing functions of damage location and depth are approximated by means of surface-fitting techniques to gain damage detection database of forward problem. Then the first three measured natural frequencies are employed as inputs to solve inverse problem and the intersection of the three frequencies contour lines predict the damage location and depth. The DLL (Dynamic Linkable Library) file of damage detection method is coded by C++ and the corresponding interface of software is coded by virtual instrument software LabVIEW. Finally, the software is tested on beams and shafts in engineering. It is shown that the presented software can be used in actual engineering structures.