Shape optimization is needed to enhance the performance or efficiency of many industrial products, for instance, such as small-scale electric parts, automotive design and so on. In, especially, small-scale apparatus with heat transfer, it is not easy to decide optimal shape of apparatus. Therefore, the shape of power auxiliary apparatus in automotive engine was investigated using numerical analysis which includes k- model and unsteady state. The relations between temperature and heat transfer were simulated in case of 3 Type and 3 Point for power auxiliary apparatus. As the results, the heat transfer was decreased due to flow recirculation in case of Type-1. Further high temperature did not always mean high heat transfer when the shape interacted with surrounding fluid.

High voltage electric power transmitter GIS(Gas Insulated Switchgear) above 72.5kV needs to satisfy domestic Korean peninsular standard(ES-6110-0002) in KEPCO with respect to normal and special operation conditions which include internal gas pressure, dead weight, wind and seismic load. Some other requirements not described in Korean standard can be applied from other international standards such as IEC(International Electronical Committee) 62271-203 and 62271-207. The GIS is a kind of pressure vessel structure made of aluminum and filled with SF6 gas of internal pressure 0.4～0.5MPa. Finite element analysis of GIS is performed with such operational loads including seismic loading and the stability and reliability is determined according to ASME BPVC(Boiler and Pressure Vessel Code) SEC. VIII standard where the allowable stress level of the pressure vessel is suggested. The result shows that the stress of GIS is satisfied the allowable stress level and the safety factor is about 2.3 for Korean peninsular standard.

본 연구에서는 공급수의 Blending 및 ERD 적용을 통해 역삼투 공정의 소비전력량을 비교 분석하였다.

Numerical analysis using k-ε model of unsteady state was performed to decide the optimal shape of power auxiliary apparatus in automotive engine. In order to obtain auxiliary electric power using coolant in automotive engine, shapes of 3 Types were compared. Furthermore to achieve the confidence of numerical analysis, the results of numerical analysis was compared with those of experiment. As the results, it showed that accuracy of numerical analysis was about 85~98%. Further the optimal shape, in this study, was Type-1, which had outer rounding R32.5, among 3 Types.

Pressure retarded osmosis (PRO) processes can be implemented on a number of water types, using different technologies and achieving various power outcomes. In this study, Sewage facility effluent was used for feed solution of PRO and synthetic NaCl water for draw solution. This study was conducted to investigate effect of water quality of pretreatment on power density and flux decline in PRO process. The results show that organic and particulate foulants have to be removed for more stable operation. Flourescence technique with EEM enables to investigate the chemical properties of aquatic organic matter by extracting spectral information. Humic/fulvic matters and soluble microbial by-products were analyzed as the most affecting factors on the PRO performance. As a result of analyzing the whole system based on the energy consumption of the unit process, specific energy consumption(SEC) of the applicable technology for PRO pre-treatment should be about 0.2 kWh/m3 or less.

동절기에 공정육묘장에서 난방 에너지 절감과 우량묘 생산을 위해 나노탄소섬유적외선 난방등(NCFIHL, nanocarbon fiber infrared heating lamp)의 적정 전력과 설치 높이를 구명하는 것이 본 연구의 목적이다. 벤로형 유리 온실 내부에 수박 접목묘를 재배하기 위해 700과 900W NCFIHL을 육묘 베드(1.2 × 2.4m)에서 0.7, 1.0, 및 1.3m 높이로 각각 설치하였다. 수박(Citrullus lanatus (Thunb.) Manst.) ‘지존꿀’과 박(Lagenaria leucantha Rusby.) ‘선봉장’은 각각 접수와 대목으로 사용되었다. 접수와 대목은 편엽합접 방식으로 접목되었다. NCFIHL의 광도는 모든 처리에서 1μmol·m-2·s-1 이하였다. NCFIHL의 광분포는 대부분 적외선 영역에서 나타났다. 외기온도가 10oC 이하일 때 700과 900W NCFIHL을 0.7m 높이로 설치한 처리구와 900W NCFIHL을 1.0m 높이로 설치한 처리에서 야간 설정온도(20oC)를 유지하였다. 열화상 촬영에서는 900W NCFIHL을 0.7m 높이로 설치한 처리에서 가장 빨리 식물체의 온도가 올라갔다. Compactness는 700W NCFIHL을 1.3m 높이로 설치한 처리에서 우수하였다. 결과적으로 700W NCFIHL을 1.0m 이상으로 설치하는 것이 바람직하다고 판단된다.

해양구조물에 전기 안전사고가 급증하면서 전력시스템 고조파 분야가 최근 많은 관심 받고 있다. 이것은 주로 비선형 (또는 고조파 생성) 부하가 일반적인 산업플랜트 전력시스템에서 계속 증가되고 있기 때문이다. 해양플랜트에서는 전력시스템의 안전설계로 인하여 고조파 문제의 발생률은 낮지만, 고조파 문제에 대한 인식은 전력시스템 설계의 신뢰성을 향상시키는데 여전히 도움이 될 수 있다. 전력시스템에 고조파 문제가 드물게 발생되는 경우, 이는 생성된 고조파의 크기 혹은 전력시스템의 공진 때문이다. 이 고조파 비교분석에 관한 연구는 전력부하를 고려한 부유식 액화천연가스 생산·저장·하역 (FLNG) 설비의 하역 운전 시나리오에 대한 전기적인 구성으로 비교분석하였다. 전기적인 네트워크 구성은 전기적인 네트워크 부하 흐름에서 볼 수 있다. 본 연구는 해양플랜트 전력시스템의 안전을 보장하기 위해 전기 모터 시스템의 고조파 효율에 초점을 맞추어 전력시스템 성능을 시뮬레이션을 통해 검증하였다. 또한, 본 연구의 설계분야에서도 운전 및 유지·보수의 향상시키기 위해 FLNG 설비의 전력시스템을 분석하였다.

Hydrogen sulfide (H2S) emitted from various sources is a major odorous compound, and non-thermal plasma (NP) has emerged as a promising technique to eliminate H2S. This study was conducted to investigate lab-scale and pilot-scale NP reactors using corona discharge for the removal of H2S, and the effects of relative humidity, applied electrical power on reactor performance and ozone generation were determined. A gas stream containing H2S was injected to the lab-scale NP reactor, and the changes in H2S and ozone concentration were monitored. In the pilotscale NP experiment, the inlet concentration and flow rate were modified to determine the effect of relative humidity and applied power on the NP performance. In the lab-scale NP experiments, H2S removal was found to be the 1st-order reaction in the presence of ozone. On the other hand, when plasma reaction and ozone generation were initiated after H2S was introduced, the H2S oxidation followed the 0th-order kinetics. The ratio of indirect oxidation by ozone to the overall H2S removal was evaluated using two different experimental findings, indicating that approximately 70% of the overall H2S elimination was accounted for by the indirect oxidation. The pilotscale NP experiments showed that H2S introduced to the reactor was completely removed at low flow rates, and approximately 90% of H2S was eliminated at the gas flow rate of 15 m3/min. Furthermore, the elimination capacity of the pilot-scale NP was 3.4 g/m3·min for the removal of H2S at various inlet concentrations. Finally, the experimental results obtained from both the lab-scale and the pilot-scale reactor operations indicated that the H2S mass removal was proportional to the applied electrical power, and average H2S masses removed per unit electrical power were calculated to be 358 and 348 mg-H2S/kW in the lab-scale and the pilot-scale reactors, respectively. To optimize energy efficiency and prevent the generation of excessive ozone, an appropriate operating time of the NP reactor must be determined.

In this paper, we utilize a Gaussian process to predict the power consumption in the air-conditioning system. As the power consumption in the air-conditioning system takes a form of a time-series and the prediction of the power consumption becomes very important from the perspective of the efficient energy management, it is worth to investigate the time-series model for the prediction of the power consumption. To this end, we apply the Gaussian process to predict the power consumption, in which the Gaussian process provides a prior probability to every possible function and higher probabilities are given to functions that are more likely consistent with the empirical data. We also discuss how to estimate the hyper-parameters, which are parameters in the covariance function of the Gaussian process model. We estimated the hyper-parameters with two different methods (marginal likelihood and leave-one-out cross validation) and obtained a model that pertinently describes the data and the results are more or less independent of the estimation method of hyper-parameters. We validated the prediction results by the error analysis of the mean relative error and the mean absolute error. The mean relative error analysis showed that about 3.4% of the predicted value came from the error, and the mean absolute error analysis confirmed that the error in within the standard deviation of the predicted value. We also adopt the non-parametric Wilcoxon’s sign-rank test to assess the fitness of the proposed model and found that the null hypothesis of uniformity was accepted under the significance level of 5%. These results can be applied to a more elaborate control of the power consumption in the air-conditioning system.

It is critical to forecast the maximum daily and monthly demand for power with as little error as possible for our industry and national economy. In general, long-term forecasting of power demand has been studied from both the consumer’s perspective and an econometrics model in the form of a generalized linear model with predictors. Time series techniques are used for short-term forecasting with no predictors as predictors must be predicted prior to forecasting response variables and containing estimation errors during this process is inevitable. In previous researches, seasonal exponential smoothing method, SARMA (Seasonal Auto Regressive Moving Average) with consideration to weekly pattern Neuron-Fuzzy model, SVR (Support Vector Regression) model with predictors explored through machine learning, and K-means clustering technique in the various approaches have been applied to short-term power supply forecasting. In this paper, SARMA and intervention model are fitted to forecast the maximum power load daily, weekly, and monthly by using the empirical data from 2011 through 2013. ARMA(2,1,2)(1,1,1)7 and ARMA (0,1,1)(1,1,0)12 are fitted respectively to the daily and monthly power demand, but the weekly power demand is not fitted by AREA because of unit root series. In our fitted intervention model, the factors of long holidays, summer and winter are significant in the form of indicator function. The SARMA with MAPE (Mean Absolute Percentage Error) of 2.45% and intervention model with MAPE of 2.44% are more efficient than the present seasonal exponential smoothing with MAPE of about 4%. Although the dynamic repression model with the predictors of humidity, temperature, and seasonal dummies was applied to foretaste the daily power demand, it lead to a high MAPE of 3.5% even though it has estimation error of predictors.

In this paper, we investigate how the power consumption of a heat pump dryer depends on various factors in the drying process by analyzing variables that affect the power consumption. Since there are in general many variables that affect the power consumption, for a feasible analysis, we utilize the principal component analysis to reduce the number of variables (or dimensionality) to two or three. We find that the first component is correlated positively to the entrance temperature of various devices such as compressor, expander, evaporator, and the second, negatively to condenser. We then model the power consumption as a multiple regression with two and/or three transformed variables of the selected principal components. We find that fitted value from the multiple regression explains 80~90% of the observed value of the power consumption. This results can be applied to a more elaborate control of the power consumption in the heat pump dryer.

It is essential to decrease energy consumption and excess sludge to economically operate sewage treatment plant. This becomes more important along with a ban on sea dumping and exhaustion of resource. Therefore, many researchers have been study on energy consumption reduction and strategies for minimization of excess sludge production from the activated sludge process. The aeration cost account for a high proportion of maintenance cost because sufficient air is necessary to keep nitrifying bacteria activity of which the oxygen affinity is inferior to that of heterotrophic bacteria. Also, additional costs are incurred to stabilize excess sludge and decrease the volume of sludge. There were anoxic, aerobic, membrane, deairation and concentration zone in this MBR process. Continuous aeration was provided to prevent membrane fouling in membrane zone and intermittent aeration was provided in aerobic zone through ammonia sensor. So, there was the minimum oxygen to remove NH4-N below limited quantity that could be eliminated in membrane zone. As the result of this control, energy consumption of aeration system declined by between 10.4 % and 19.1 %. Besides, we could maintain high MLSS concentration in concentration zone and this induced the microorganisms to be in starved condition. Consequentially, the amount of excess sludge decrease by about 15 %.

다이오드 정류기가 AC-DC 컨버터로 산업현장에서 널리 응용되고 있다. 그러나 입력전류에 많은 저차고조파가 포함되어 전력변환 장치의 공급전압을 왜곡시켜 전력의 품질을 저하시키므로 이를 완화시킬 수 있는 적절한 설비가 필요하다. 이러한 문제점들을 개선하기 위해 본 논문에서는 정류기의 출력단에 보조 전원장치를 설치하여 고조파를 저감하는 장식을 제안하였다.