• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.176-182
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• 2008

It is the paper that this study develops the small plate-type ozonizer(PTO) for improvements of indoor air and water, and investigated the characteristics. Electric discharge area of ozonizer of each form is same to 60[$cm^2$] and discharge power is the maximum 30[W]. Ozonizer of various forms was devised according to size, numbers and arrangement. The main study object is discharge power-ozone concentration characteristics, discharge power-ozone yield characteristics, amount of gas flow-ozone concentration characteristics and amount of gas flow-ozone yield characteristics. PTOL-P appeared so as to be most excellent, and ozone generation characteristics were able to get the similar results at three kinds of remaining ozonizer ($PTO_{P-P}$, $PTO_{C-P}$, $PTO_{T-P}$).

• Fire Science and Engineering
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• v.33 no.1
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• pp.15-22
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• 2019

Refrigerator and heating cabinet fires due to the dielectric breakdown of electronic components caused by leaked beverages are being reported frequently. On the other hand, there has been little interest in measuring the electrical characteristics of beverages and studying the cause of fires. In this paper, the electrical conductivity and total dissolved solids (TDS) for 32 different beverages commonly sold in South Korea were measured to study the relationship between the electrical conductivity and dielectric breakdown. Out of these 32 beverages, based on the measurements, some characteristic beverages were selected and further dielectric breakdown tests were conducted. The results showed that the probability of a fire is higher for beverages with high electrical conductivity. Interestingly, beverages with low electrical conductivity had a high likelihood of fire depending on the type of beverage. Moreover, some conditions that cause spark ignition, which lead to fires in electronic components, were identified.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.8
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• pp.117-125
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• 2015

In this paper, we propose a classification algorithm based on the obtained EEG(Electroencephalogram) signal for the control of 'left' and 'right' turnings of which a driving system composed of EEG sensor, Labview, DAQ, Matlab and driving robot. The proposed algorithm uses features extracted from frequency band information obtained by DWT (Discrete Wavelet Transform) and selects features of high discrimination by using Fisher score. We, also propose the number of feature vectors for the best classification performance by using SVM(Support Vector Machine) classifier and propose a decision pending algorithm based on MLD (Maximum Likelihood Decision) to prevent malfunction due to misclassification. The selected four feature vectors for the proposed algorithm are the mean of absolute value of voltage and the standard deviation of d5(2-4Hz) and d2(16-32Hz) frequency bands of P8 channel according to the international standard electrode placement method. By using the SVM classifier, we obtained 98.75% accuracy and 1.25% error rate. Also, when we specify error probability of 70% for decision pending, we obtained 95.63% accuracy and 0% error rate by using the proposed decision pending algorithm.

• Journal of the Korean Vacuum Society
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• v.11 no.2
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• pp.113-118
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• 2002

We developed engineering methods to control gas flow in a plasma reactor in order to achieve good etch depth uniformity for large area GaAs etching. Finite difference numerical method was found quite useful for simulation of gas flow distribution in the reactor for dry etching of GaAs. The experimental results in $BCl_3/N_2/SF_6/He$ ICP plasmas confirmed that the simulated data fitted very well with real data. It is noticed that a focus ring could help improve both gas flow and etch uniformity for 150 mm diameter GaAs plasma etch processing. The simulation results showed that optimization of clamp configuration could decrease gas flow uniformity as low as $\pm$ 1.5% on an 100 mm(4 inch) GaAs wafer and $\pm$ 3% for a 150 m(6 inch) wafer with the fixed reactor and electrode, respectively. Comparison between simulated gas flow uniformity and real etch depth distribution data concluded that control of gas flow distribution in the chamber would be significantly important in order or achieve excellent dry etch uniformity of large area GaAs wafers.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.361-361
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• 2013

비냉각 적외선 검출소자는 빛이 전혀 없는 환경에서도 사물을 감지하는 열상장비의 핵심소자이다. 마이크로볼로미터 적외선 검출기는 상온에서 동작하며, 온도안정화를 위해 TEC를 장착하여 진공패키지로 조립된다. 패키지는 진공을 유지할 수 있도록 일반적으로 메탈로 제작되며, 단가 감소 및 생산성 증대를 위해 wafer level packaging 방법을 이용한다. 마이크로볼로미터의 특성은 패키지의 진공 변화에 매우 민감하다. 센서의 감도를 증가시키기 위해서는 진공환경을 유지해야 한다. 볼로미터 소자의 특성은 상압에서 열전도는 기판과 멤브레인 사이의 에어갭을 통해 열손실을 야기하므로 센서의 반응도가 현저히 줄어든다. 에어갭이 1 um 정도 되더라도 그 사이에 존재하는 열전도가 가능하므로 진공을 유지하여 열고립 상태를 증대시킬 수 있다. 이에 본 연구에서는 소자의 동작시 압력, 즉 진공도가 볼로미터 소자의 반응도 특성에 미치는 영향을 조사하였다. 마이크로볼로미터 소자는 $2{\times}8$ 어레이 형태로 제작하였으며, metal pad를 각 단위셀에 배치하였으며, 공통전극으로 한 개의 metal pad를 넣어 설계하였다. 흡수체로써 VOx를 사용하였으며, 열 고립구조를 위해 2.5 um 공명 흡수층의 floating 구조로 멤브레인을 형성하였다. 진공패키지는 메탈패키지를 제작하여 볼로미터 칩을 TEC 위에 장착하였으며, 신호의 감지를 위해 가변저항을 매칭시켰다. 반응도는 신호 대 잡음 값을 획득하여 소자에 도달하는 적외선 에너지에 대해 반응하는 값을 계산에 의해 얻어내는 것이다. 픽셀 크기는 $50{\times}50$ um이며, 패키지 조립 공정 후 온도변화에 따른 저항 측정을 통해 TCR 값을 얻었다. 이때 TCR은 약 -2.5%/K으로 나타났다. $2{\times}8$의 4개 단위소자에 대해 측정한 값은 균일하게 TCR 값이 나타났다. 광반응 특성은 볼로미터 단위소자에 대해서 먼저 고진공(5e-6 torr) 하에서 측정하였으며, 반응도는 25,000 V/W의 값을 나타내었고, 탐지도는 약 2e+8 $cmHz_{1/2}$/W로 나타났다. 패키지의 압력 조절을 위해 TMP 및 로터리 펌프를 이용하여 100 torr에서 1e-4 torr의 범위에서 압력조절 밸브를 이용하여 질소가스의 압력으로 진공도를 변화시켰다. 적외선 반응신호는 압력이 증가함에 따라 감소하였으며, 2e-1 torr의 압력에서 신호의 크기가 감소하기 시작하여 5 torr에서 반응도의 1/2 값을 나타냄을 알 수 있었다. 30 torr 이상에서는 신호가 잡음값 과거의 동일하여 신호대 잡음비가 1로 나타남을 알 수 있었다. 또한 진공도 변화에 대해, 흑체온도에 따른 반응도 및 탐지도의 특성을 조사한 결과를 발표한다. 반응도의 증가를 위해 진공도는 진공도는 1e-2 torr 이하의 압력을 유지해야 함을 본 실험을 통해 알 수 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.985-993
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• 2014

This paper suggested a new evaluation method for optimal HUD position through a correlation based on between biological signal as and statistical analysis which using (Electroencephalogram, EEG) and ANOVA. This experiment was conducted two kinds of method to evaluate the optimal HUD position. At first, visual stimulus suggested from six different positions(the top and the bottom of the left, the top and the bottom of the center and the top and the bottom of the right on the screen) in laboratory and an object image was shown for 30 seconds in a screen which has $235{\times}197cm2$ size. And second, HUD image was configured from three different positions and an object image was shown for 30 seconds in a screen. EEG, which used ${\alpha}$-wave and ${\beta}$-wave for evaluate an emotional stability, were measured from Fp1, Fp2, F7 and F8 channel based on ten to twenty electrode system. From the result in laboratory, F7 ${\beta}$-wave was shown statistically significant to significance probability of 0.006 and between ${\alpha}$-wave and ${\beta}$-wave were showed a negative correlation(r=-0.190). Also, Both the top of left and the bottom of center were showed lower ${\beta}$-wave than the bottom of right. From the result in railway simulator, Fp1 ${\beta}$-wave was appeared statistically significant as significance probability of 0.033 and it was showed lower ${\beta}$-wave than center. The outcome of this study will be helpful about evaluation of optimal HUD position through correlation between alpha wave and beta wave.

• Journal of the Korean Society for Environmental Technology
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• v.19 no.6
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• pp.556-562
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• 2018

Due to the enforcement of effluent water regulation the advance sewage treatment system is needed to retrofit and remodelling. In this case the most important issue is the effluent concentrations of TP and there are a lot of system to reduce its concentration. But biological treatment processes have many restrictions to enhance the removal efficiency of TP. In this study the efficient ECO operating condition to improve and retrofit biological sewage wastewater treatment system is as follow; 1) The treatment efficiency of BOD, TN and TP at the current density of $15mA/cm^2$ was higher than the treatment efficiency at $5mA/cm^2$ in the electrodes arranged with Al-SUS(Stainless Steel) regardless of the reaction time, The TP concentration was 0.1 mg/L or less. Especially, when the reaction time was maintained at 10 min, the TP concentration was 0.06 mg/L or less irrespective of the current density. 2) The change of TP concentration is not influenced by the change of current density and rather the concentration of treated water changes according to the reaction time. In the case of electro coagulation reaction, a few seconds to several minutes are required. However, the reaction time of electro coagulation and oxidation was studied to be more than 10 minutes. 3) As a result, it has been studied that the economical current density of the electro coagulation oxidation process for TN and TP treatment of domestic wastewater is $15mA/cm^2$ or less and the reaction time is 10 minutes.