• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.363-368
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• 2008

Nitrogen oxides (NO, $NO_2$ and $N_2O$) have been controlled effectively by the SCR catalysts coated on monolith or honeycomb in commercial sites with ammonia as reductant at high temperature range $300{\sim}400^{\circ}C$. However, the catalytic filter has much merit on the point of controlling the particles and nitrogen oxides simultaneously. It will be more advanced-system if the catalytic working temperature is reduced to the normal filtration temperature of under $200^{\circ}C$. This study has focus on the development of the catalytic filter working at the low temperature. So the additive effect of the components such as Pt and Mn (which are known the catalytic component of $V_2O_5/TiO_2$ was investigated. The $V_2O_5-WO_3$ catalytic filter exhibited high activity and selectivity at $250{\sim}320^{\circ}C$ showing more than 95% NO conversion for the treatment of 600 ppm NO at face velocity 2 cm/s. The Pt-$V_2O_5-WO_3$ catalytic filter shifted the optimum working temperature towards the lower temperature ($170{\sim}200^{\circ}C$). And NO conversion was 100% and higher than that of $V_2O_5-WO_3$ catalyst at $250{\sim}320^{\circ}C$. The $MnO_X-V_2O_5-WO_3$ catalytic filter showed the wide temperature range of $220{\sim}330^{\circ}C$ for more than 95% NO conversion. This is a remarkable advantage when considered the $MnO_X$ catalytic filter presents the maximum activity at $150{\sim}250^{\circ}C$ and $V_2O_5-WO_3$ catalytic filter shows the maximum activity at $250{\sim}320^{\circ}C$.

• 한국재료학회지
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• 제19권4호
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• pp.198-202
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• 2009

For use in ultrasonic actuators, we investigated the structural and piezoelectric properties of $(1\;-\;x)Pb(Zr_{0.515}Ti_{0.485})O_3$ - $xPb(Sb_{1/2}Nb_{1/2})O_3$ + 0.5 wt% $MnO_2$ [(1 - x)PZT - xPSN + $MnO_2$] ceramics with a variation of x (x = 0.02, 0.04, 0.06, 0.08). All the ceramics, which were sintered at $1250^{\circ}C$ for 2 h, showed a typical perovskite structure, implying that they were well synthesized. A homogeneous micro structure was also developed for the specimens, and their average grain size was slightly decreased to $1.3{\mu}m$ by increasing x to 0.8. Moreover, a second phase with a pyrochlore structure appeared when x was above 0.06, which resulted in the deterioration of their piezoelectric properties. However, the 0.96PZT-0.04PSN+$MnO_2$ ceramics, which corresponds with a morphotropic phase boundary (MPB) composition in the (1 - x)PZT - xPSN + $MnO_2$ system, exhibited good piezoelectric properties: a piezoelectric constant ($d_{33}$) of 325 pC/N, an electromechanical coupling factor ($k_p$) of 70.8%, and a mechanical quality factor ($Q_m$) of 1779. The specimens with a relatively high curie temperature ($T_c$) of $305^{\circ}C$ also showed a significantly high dielectric constant (${\varepsilon}_r$) value of 1109. Therefore, the 0.96PZT - 0.04PSN + $MnO_2$ ceramics are suitable for use in ultrasonic vibrators.

• 청정기술
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• 제28권1호
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• pp.79-93
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• 2022

본 연구에서는 Part I에서 제안한 첨단 전자산업 폐수처리시설 특화 Water Digital Twin모델인 e-ASM을 이용하여 랩-파일럿 처리장 데이터를 바탕으로 모델 보정(Calibration), 유입 성상에 따른 제거 효율, 유출수 예측 및 최적 공법 선정을 수행하였다. 첨단 전자산업 폐수처리시설의 특화 모델링을 위하여, 민감도 분석을 통해 e-ASM 모델의 정합성과 상관성이 높은 동역학적 파라미터를 선정하였고, 다중반응표면분석법 (Multiple response surface methodology, MRS)을 이용하여 동역학적 파라미터를 보정하였다. e-ASM 모델의 보정 결과, Lab-scale, Pilot-scale 단위의 실험데이터와 90% 이상의 높은 정합성을 보였다. 그리고 4가지 유기폐수 처리처리공법인 MLE, A2/O, 4-stage MLE-MBR, Bardenpho-MBR을 제안한 Water Digital Twin으로 구현하여 유입 폐수의 성상별 운전조건에 따라 제거효율을 분석하였으며, Bardenpho-MBR이 C/N ratio 변화에서도 안정적으로 COD (Chemical oxygen demand)를 90% 이상 제거하며 높은 총 질소 제거 효율을 보였다. 그리고 유입 폐수의 조건별 Bardenpho-MBR공정의 수리학적 체류시간(Hydraulic retention time, HRT)이 3일 이상일 때 1,800 mg L-1의 고농도 TMAH 폐수를 98% 이상 제거할 수 있음을 확인할 수 있었다. 이와 같이, 본 연구에서 개발한 e-ASM은 전자산업 제조시설별, 유입 폐수의 성상별 특화 모델링을 통해 높은 정합성을 가진 전자산업 폐수처리공정의 Water Digital Twin를 구현할 수 있고, 최적운전, Water AI, 최적가용기법 선정 등의 응용 가능성을 바탕으로 지속 가능한 첨단전자 산업을 위해 활용될 수 있을 것으로 사료된다.

• The Plant Pathology Journal
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• 제20권4호
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• pp.289-292
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• 2004

The population of Ralstonia solanacearum (Rs) in soil is very important as a primary inoculum source of bacterial wilt in tobacco fields. To investigate the population of Rs, physical properties and chemical components during the tobacco growing season, soil samples were taken from the fifteen fields which were located in the flue-cured tobacco growing area, Ansung, Kyunggi province and Wonju, Kangwon province. Two fields of the fifteen were bacterial wilt free. Six fields had less than 10% plants being diseased and seven over 10%. The Rs population level determined by using SMSA medium generally showed an up-and-down pattern being low in May, high in Jun and July and low in August. The soil population in May and June showed a positive correlation with the incidence of bacterial wilt (r=0.571$^*$, r=0.688$^{**}$), but P$_2O_5$, content of soil was negatively correlated with the disease incidence (r=-0.539$^*$). These results suggest that Rs population in soil examined in May or in June, and the P$_2O_5$ content in soil should be key factors to determine the bacterial wilt potential of tobacco fields.

• 한국가시화정보학회지
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• 제14권1호
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• pp.40-45
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• 2016

Elimination of the smear layer and bacteria in the root canal is the most important in the endodontic treatment, and various irrigation devices have been developed. Nevertheless, it is hard to eliminate the smear layer and bacteria completely. In this paper, a micro bubble irrigation system has been developed for the root canal cleaning of tooth. Micro bubbles are generated when pressurized fluids passing through a porous material inside a hand-piece nozzle, and the bubbly flows excited by ultrasonic vibration are observed using a high-speed camera and a microscope. The results show that the diameter and number of bubbles increases with the applied pressure, and there found an optimum excitation frequency in order to minimize the bubble size. From in-vitro tests, it is also verified that the developed bubble irrigation system has the ability of antibacterial and infection removal. Thus, this biocompatible system would be well suited for root canal cleaning.

• Nutrition Research and Practice
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• 제5권2호
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• pp.163-168
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• 2011

This study was conducted to evaluate recipients' perception of service quality, satisfaction, and behavioral intention in home delivered meals program in the US. Out of 398 questionnaires, 265 (66.6%) were collected, and 209 questionnaires (52.5%) were used for the statistical analysis. A Confirmatory Factor Analysis (CFA) with a maximum likelihood was first conducted to estimate the measurement model by verifying the underlying structure of constructs. The level of internal consistency in each construct was acceptable, with Cronbach's alpha estimates ranging from 0.7 to 0.94. All of the composite reliabilities of the constructs were over the cutoff value of 0.50, ensuring adequate internal consistency of multiple items for each construct. As a second step, a Meals-On-Wheels (MOW) recipient perception model was estimated. The model's fit as indicated by these indexes was satisfactory and path coefficients were analyzed. Two paths between (1) volunteer issues and behavioral intention and (2) responsiveness and behavioral intention were not significant. The path for predicting a positive relationship between food quality and satisfaction was supported. The results show that having high food quality may create recipient satisfaction. The findings suggest that food quality and responsiveness are significant predictors of positive satisfaction. Moreover, satisfied recipients have positive behavioral intention toward MOW programs.

• 한국추진공학회지
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• 제21권2호
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• pp.72-82
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• 2017

무노즐 부스터는 통합형 로켓 램제트 추진기관에 적용되는 구성품 중 하나이다. 무노즐 고체 부스터의 성능을 예측하기 위해서 간단한 이론적 해석이 L/D=5, 6, 7, 9, 11, 그리고 13에 적용되었다. 연소가스 유동 효과 때문에 경도를 증가시키기 위해서 금속함량이 높은 Al-HTPB 및 Zr-HTPB 추진제가 사용되었다. 간단한 이론 해석과 시험결과 사이의 경향은 유사하게 나타났다.

• 한국식품영양과학회지
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• 제36권3호
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• pp.255-259
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• 2007

The solvent extracts of Oenothera laciniata, which were extracted by using several solvents with different polarities, were prepared for utility as a natural preservative. The O. laciniata extract by 80% ethanol was sequentially fractionated with n-hexane, dichloromethane, ethylacetate, and butanol. The antibacterial activities and cell growth inhibition were investigated on each strain with the different concentrations of O. laciniata extracts. Antibacterial activities were shown in ethanol, ethylacetate, and butanol fraction of O. laciniata. However n-hexane, dichloromethane and water fraction showed weak antibacterial activity against the tested microorganisms. Among the five fractions, ethylacetate fraction showed the highest antibacterial activities against microorganisms tested, such as Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Salmonella Enteritidis and Salmonella Typhimurium. The polyphenolic compounds widely occurring in the traditional medicine plants have been reported to possess high antibacterial activity. The polyphenolic compounds from ethanol, n-hexane, dichloromethane, ethylacetate, butanol, and water fraction were 63.96 mg/g, 8.49 mg/g, 28.11 mg/g, 172.64 mg/g, 114.56 mg/g, and 34.91 mg/g, respectively. There are some relationships between antibacterial activity and polyphenol content in natural plant. The ethylacetate fraction could be suitable for the development of a food preservative.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.769-774
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• 2016

In the design of sensorless control system for induction motor, high-precision speed estimation is one of the most difficult problems. To solve this problem, the common method is model reference adaptive method (MRAS). MRAS requires accurate motor parameters to estimate rotor speed precisely. However, when motor is running, the variety of temperature and magnetic saturation will lead to the change of motor parameters such as stator resistance and rotor resistance, which will lower the accuracy of the speed estimation. To improve the accuracy and rapidity of speed estimation, this paper analyses the mutual MRAS speed identification based on rotor flux linkage, and proposes an improved mutual MRAS speed identification based on back-EMF. The improved method is verified by Simulink simulation and motor experimental platform based on DSP2812. The results of simulation and experiment indicate that the method proposed by this paper can significantly improve the accuracy of speed identification, and speed up the response of identification.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.191-193
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• 2008

A fuel cell power system among various alternative power sources has many advantages such as low-polluted, high-efficient, and heat-recyclable, thus it is now able to be up to hundreds MWh-scaled through improving feasibility and longevity of it. During the last few years of the twentieth century, much changed to stimulate new and expanding interest in fuel cell technology. This paper presents optimal design and operational features of stand-alone 500W PEMFC(Proton Exchange Membrane Fuel Cell) system which can be a substitute instead fossil fuel. The stack of PEMFC is composed of 35 laminated graphite, and a unit cell of the stack has electrical characteristics as below; 14W, 0.9V, 15A. The other components of BOP(Balance of Plant) are composed of hydrogen and nitrogen tanks, regulators, 3way 5solenoid valves, mass flow meters, etc.