• Title/Summary/Keyword: system generator

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Design of Ultrasonic Nebulizer for Inhalation Toxicology Study of Cadmium with Application of Engineering Methodology and Performance Evaluation with Light-Scattering Photometer (공학적 기법을 응용한 카드뮴의 흡입독성 연구를 위한 초음파 네뷸라이져의 설계 그리고 광산란 광도계를 이용한 성능평가)

  • Jeung Jae Yeal;Milton Donald K.;Kim Tae Hyeung;Lee Jong Young;Chong Myoung Soo;Ko Kwang Jae;Kim Sang Duck;Kang Sung Ho;Song Young Sun;Lee Ki Nam
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.16 no.3
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    • pp.464-471
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    • 2002
  • Author applied several engineering methodologies to classical ultrasonic nebulizer to cope with it's demerits. After several trials and errors, we got the several meaningful results. To evaluate the modified ultrasonic nebulizer for inhalation toxicology of cadmium, author used light-scattering photometer. This paper is the one part of inhalation exposure systems for inhalation toxicology study of cadmium. According to the testing conditions, source temperature 50℃ and inlet-duct band temperature 150℃, aerosol generation results for sodium chloride and cadmium chloride were as followings: Coefficients of variation(CV) of sodium chloride and cadmium chloride for repeated trials were 3.38 and 4.77 for 10g, 2.47 and 5.02 for 5g, and 4.70 and 2.98 for 2.5g. All the CVs were within 10% of acceptance variability. Count Per Minute(CPM) changes of NaCl and CdCl₂ for 5 repeated trials were similar. CPM ratios of CdCl₂/NaCl were 1.13 for 10g, 0.76 for 5g, and 1.06 for 2.5g. Relative aerosol generation of cadmium chloride to sodium chloride was the highest in 10g. Efficiency increases of 24.50% for 5g NaCl, 14.91 % for 2.5g NaCl, and 16.48% for 2.5g CdCl₂ with respect to theoretical efficiency were observed but 0.04% efficiency decrease was observed in 5g CdC₂. According to the modifications of source temperature(20, 50, 70℃) and inlet-duct band temperature(20, 50, 100, 150, 200℃), aerosol generation results for NaCl and CdCl₂ were as followings: CPM trends for each quantity excepting 10g NaCl in inlet-duct band temperature 200℃ were similar, and the highest CPM was observed in source temperature 70℃ to each inlet-duct band temperature. The highest CPMs to 10, 5, and 2.5g NaCl were observed in source temperature 70℃ and inlet-duct band temperature 20℃. Aerosol generation of cadmium chloride was increased with the higher source temperature, excepting inlet-duct band temperature 200℃. The highest CPMs for 10, 5, and 2.5g CdCl₂ were observed in source temperature 70℃ and inlet-duct band temperature 20℃, and this trend was similar to NaCl aerosol generation The highest CPMs for 10, 5, and 2.5g CdCl₂ were observed in source temperature 70℃ and inlet-duct band temperature 20℃, and this result was similar to NaCl aerosol generation. Observed efficiencies of 5 and 2.5g NaCl were similar to ifs theoretical efficiency but -3.08% efficiency decrease of 5g CdCl₂, 17.47% efficiency increase of 2.5g CdCl₂ were observed. CPM ratio of CdCl₂/NaCl of 10g was different to 5 and 2.5g, and 2.5g ratio was higher than 5g ratio. In conclusion, to get maximum aerosol generation for NaCl and CdCl₂ will be the conditions that set the appropriate inlet-duct band temperature for each materials and increase the source temperature. Sodium chloride can be used to evaluate the performance and predict the concentration for cadmium aerosol in aerosol generator and inhalation exposure system.

Study on Hydrogen Production and CO Oxidation Reaction using Plasma Reforming System with PEMFC (고분자 전해질 연료전지용 플라즈마 개질 시스템에서 수소 생산 및 CO 산화반응에 관한 연구)

  • Hong, Suck Joo;Lim, Mun Sup;Chun, Young Nam
    • Korean Chemical Engineering Research
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    • v.45 no.6
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    • pp.656-662
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    • 2007
  • Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.

A Design of PLL and Spread Spectrum Clock Generator for 2.7Gbps/1.62Gbps DisplayPort Transmitter (2.7Gbps/1.62Gbps DisplayPort 송신기용 PLL 및 확산대역 클록 발생기의 설계)

  • Kim, Young-Shin;Kim, Seong-Geun;Pu, Young-Gun;Hur, Jeong;Lee, Kang-Yoon
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.47 no.2
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    • pp.21-31
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    • 2010
  • This paper presents a design of PLL and SSCG for reducing the EMI effect at the electronic machinery and tools for DisplayPort application. This system is composed of the essential element of PLL and Charge-Pump2 and Reference Clock Divider to implement the SSCG operation. In this paper, 270MHz/162MHz dual-mode PLL that can provide 10-phase and 1.35GHz/810MHz PLL that can reduce the jitter are designed for 2.7Gbps/162Gbps DisplayPort application. The jitter can be reduced drastically by combining 270MHz/162MHz PLL with 2-stage 5 to 1 serializer and 1.35GHz PLL with 2 to 1 serializer. This paper propose the frequency divider topology which can share the divider between modes and guarantee the 50% duty ratio. And, the output current mismatch can be reduced by using the proposed charge-pump topology. It is implemented using 0.13 um CMOS process and die areas of 270MHz/162MHz PLL and 1.35GHz/810MHz PLL are $650um\;{\times}\;500um$ and $600um\;{\times}\;500um$, respectively. The VCO tuning range of 270 MHz/162 MHz PLL is 330 MHz and the phase noise is -114 dBc/Hz at 1 MHz offset. The measured SSCG down spread amplitude is 0.5% and modulation frequency is 31kHz. The total power consumption is 48mW.

Optimal Operation of Gas Engine for Biogas Plant in Sewage Treatment Plant (하수처리장 바이오가스 플랜트의 가스엔진 최적 운영 방안)

  • Kim, Gill Jung;Kim, Lae Hyun
    • Journal of Energy Engineering
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    • v.28 no.2
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    • pp.18-35
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    • 2019
  • The Korea District Heating Corporation operates a gas engine generator with a capacity of $4500m^3 /day$ of biogas generated from the sewage treatment plant of the Nanji Water Recycling Center and 1,500 kW. However, the actual operation experience of the biogas power plant is insufficient, and due to lack of accumulated technology and know-how, frequent breakdown and stoppage of the gas engine causes a lot of economic loss. Therefore, it is necessary to prepare technical fundamental measures for stable operation of the power plant In this study, a series of process problems of the gas engine plant using the biogas generated in the sewage treatment plant of the Nanji Water Recovery Center were identified and the optimization of the actual operation was made by minimizing the problems in each step. In order to purify the gas, which is the main cause of the failure stop, the conditions for establishing the quality standard of the adsorption capacity of the activated carbon were established through the analysis of the components and the adsorption test for the active carbon being used at present. In addition, the system was applied to actual operation by applying standards for replacement cycle of activated carbon to minimize impurities, strengthening measurement period of hydrogen sulfide, localization of activated carbon, and strengthening and improving the operation standards of the plant. As a result, the operating performance of gas engine # 1 was increased by 530% and the operation of the second engine was increased by 250%. In addition, improvement of vent line equipment has reduced work process and increased normal operation time and operation rate. In terms of economic efficiency, it also showed a sales increase of KRW 77,000 / year. By applying the strengthening and improvement measures of operating standards, it is possible to reduce the stoppage of the biogas plant, increase the utilization rate, It is judged to be an operational plan.

Anomaly Detection for User Action with Generative Adversarial Networks (적대적 생성 모델을 활용한 사용자 행위 이상 탐지 방법)

  • Choi, Nam woong;Kim, Wooju
    • Journal of Intelligence and Information Systems
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    • v.25 no.3
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    • pp.43-62
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    • 2019
  • At one time, the anomaly detection sector dominated the method of determining whether there was an abnormality based on the statistics derived from specific data. This methodology was possible because the dimension of the data was simple in the past, so the classical statistical method could work effectively. However, as the characteristics of data have changed complexly in the era of big data, it has become more difficult to accurately analyze and predict the data that occurs throughout the industry in the conventional way. Therefore, SVM and Decision Tree based supervised learning algorithms were used. However, there is peculiarity that supervised learning based model can only accurately predict the test data, when the number of classes is equal to the number of normal classes and most of the data generated in the industry has unbalanced data class. Therefore, the predicted results are not always valid when supervised learning model is applied. In order to overcome these drawbacks, many studies now use the unsupervised learning-based model that is not influenced by class distribution, such as autoencoder or generative adversarial networks. In this paper, we propose a method to detect anomalies using generative adversarial networks. AnoGAN, introduced in the study of Thomas et al (2017), is a classification model that performs abnormal detection of medical images. It was composed of a Convolution Neural Net and was used in the field of detection. On the other hand, sequencing data abnormality detection using generative adversarial network is a lack of research papers compared to image data. Of course, in Li et al (2018), a study by Li et al (LSTM), a type of recurrent neural network, has proposed a model to classify the abnormities of numerical sequence data, but it has not been used for categorical sequence data, as well as feature matching method applied by salans et al.(2016). So it suggests that there are a number of studies to be tried on in the ideal classification of sequence data through a generative adversarial Network. In order to learn the sequence data, the structure of the generative adversarial networks is composed of LSTM, and the 2 stacked-LSTM of the generator is composed of 32-dim hidden unit layers and 64-dim hidden unit layers. The LSTM of the discriminator consists of 64-dim hidden unit layer were used. In the process of deriving abnormal scores from existing paper of Anomaly Detection for Sequence data, entropy values of probability of actual data are used in the process of deriving abnormal scores. but in this paper, as mentioned earlier, abnormal scores have been derived by using feature matching techniques. In addition, the process of optimizing latent variables was designed with LSTM to improve model performance. The modified form of generative adversarial model was more accurate in all experiments than the autoencoder in terms of precision and was approximately 7% higher in accuracy. In terms of Robustness, Generative adversarial networks also performed better than autoencoder. Because generative adversarial networks can learn data distribution from real categorical sequence data, Unaffected by a single normal data. But autoencoder is not. Result of Robustness test showed that he accuracy of the autocoder was 92%, the accuracy of the hostile neural network was 96%, and in terms of sensitivity, the autocoder was 40% and the hostile neural network was 51%. In this paper, experiments have also been conducted to show how much performance changes due to differences in the optimization structure of potential variables. As a result, the level of 1% was improved in terms of sensitivity. These results suggest that it presented a new perspective on optimizing latent variable that were relatively insignificant.