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191.
The dye adsorption process for dye-sensitized solar cells (DSSCs) is the most rate limiting step, usually consuming up to 24 h depending on the film thickness and particle size. In this study, we propose a simple and effective method to reduce the dye adsorption time using a general bath-type ultrasonic device. Applying the ultrasonication method, the dye adsorption time was much reduced compared to the conventional dipping method for the full uptake of dye molecules. For further studies, the sole effect of solution temperature on the dye adsorption was also investigated due to the solution temperature increase during the ultrasonication process. The UV and IR absorbance analyses were performed to detect the possible structural changes of dye molecules during the ultrasonication process. 相似文献
192.
A typical problem for the parameter estimation in normal mixture models is an unbounded likelihood and the presence of many spurious local maxima. To resolve this problem, we apply the doubly smoothed maximum likelihood estimator (DS-MLE) proposed by Seo and Lindsay (in preparation). We discuss the computational issues of the DS-MLE and propose a simulation-based DS-MLE using Monte Carlo methods as a general computational tool. Simulation results show that the DS-MLE is virtually consistent for any bandwidth choice. Moreover, the parameter estimates in the DS-MLE are quite robust to the choice of bandwidths, as the theory indicates. A new method for the bandwidth selection is also proposed. 相似文献
193.
Ki-Yeol Seo Gyei-Kark Park Chang-Shing Lee Mei-Hui Wang 《Expert systems with applications》2009,36(1):755-765
The important field of research on ship operation is related to the high efficiency of transportation, the convenience of maneuvering ships, and the safety of navigation. This paper proposes an ontology-based fuzzy support agent for ship steering control and desires to testify the validity of the proposal by applying the fuzzy control model to the steering control system based on linguistic instruction. The fuzzy support agent is presented to build the maneuvering models of steersman and the miniature model for steering control system. The proposed fuzzy agent contains three main mechanisms, including the interpretation mechanism of linguistic instruction, the self-regulation mechanism, and the task performance mechanism. Furthermore, the task performance mechanism includes the kinematics module and the performance ontology. The simulation results show that the proposed approach can work effectively for ship steering control. 相似文献
194.
Siyoung Yang Seung Jun Choi Jungki Kwak Kihyun Kim Minjae Seo Tae Wha Moon Yin-Won Lee 《Food science and biotechnology》2013,22(2):425-432
Forty-seven strains of Aspergillus oryzae isolates from Korean nuruks were compared for their brewing characteristics. A. oryzae YI-A6 and YI-A7 showed the highest acid α-amylase, glucoamylase, and carboxypeptidase activities, respectively. Sixteen isolates with high amylolytic or proteolytic enzyme activities were selected for investigation of their rice wine fermentation characteristics. After 12 days of brewing at 15°C, ethanol concentrations were 10.2–14.3% for A. oryzae strains. Fermentation rates were the highest for YI-A7. Most rice wine samples fermented with nuruk strains had lower concentrations of off-flavor compounds than the control did. All mean sensory attribute values significantly differed among samples. Pearson correlation coefficients showed that glucoamylase activity was positively correlated to both ethanol productivity and overall harmony (p<0.01). Thus, glucoamylase activity was identified as the best factor for screening Aspergillus strains for use in rice wine brewing. 相似文献
195.
Sang Yong Shin Hackcheol Lee Seung Youb Han Chang-Hyo Seo Kayoung Choi Sunghak Lee Nack J. Kim Jai-Hyun Kwak Kwang-Geun Chin 《Metallurgical and Materials Transactions A》2010,41(1):138-148
An investigation was conducted into the correlation of microstructure and the cracking phenomenon that often occurred in hot-rolled
lightweight steel plates. Two kinds of steels were fabricated with varying Mn and Al contents, and their microstructures,
tensile properties, and high-temperature transformation behavior were investigated. In the two steels, banded structures containing
ferrite grains and κ-carbides were well developed along the rolling direction. Detailed microstructural analyses showed that cracks initiated
at film-type κ-carbides continuously formed interfaces between bands, while the band populated with κ-carbides did not play an important role in initiating cracks. Thus, the formation of band structures and film-type interfacial
κ-carbides must be minimized to prevent the cracking. The decreased content of hardenability elements, including aluminum,
higher finish-rolling temperature, reduced central segregation during the slabmaking process, and decreased material variation
during hot rolling, were suggested as practical methods for preventing the cracking. 相似文献
196.
In this study, we have attempted to describe the phenomenon of vacancy formation in various types of diamonds (natural type
IaAB, synthetic type Ib, synthetic type IIa, and type IaABC suspected of having been pretreated with an unknown method) using
electron beam irradiation. After the electron beam irradiation, vacancies were formed in the natural type IaAB and synthetic
type IIa diamonds, whereas vacancies were not formed in the synthetic type Ib and pre-treated type IaABC diamonds. From these
results, we suggest a model of vacancy creation by electron beam irradiation in various types of diamonds. The irradiation
was performed with electron dose densities of 1–6×1017/cm2 at 10 MeV, and with a heat treatment of two hours at a temperature of 900 °C. Electron beam-irradiated and heat-treated samples
were analyzed using UV-Vis-NIR, FT-IR, and PL spectroscopy. 相似文献
197.
H.S. Yoon J.H. Seo J.H. Kim 《International Journal of Heat and Mass Transfer》2010,53(21-22):4525-4535
The present study numerically investigates two-dimensional laminar force convection heat transfer past two rotating circular cylinders in a side-by-side arrangement at a various range of absolute rotational speeds (|α| ? 2) for four different gap spacings (g1) of 3, 1.5, 0.7 and 0.2 at Reynolds number of 100, and a fixed Prandtl numbers of 0.7 (air). As |α| increases, the thermal field became stabilized and eventually steady beyond the critical rotational speed depending on the gap spacing. In general, as |α| increases, because the vertical motion of flow in the region of gap is strongly inhibited, the inner isotherms are early merged and shorter than the outer isotherms in the free-stream sides elongating further downstream. As |α| increases, because the rotating fluid near the cylinders surrounded much space where the steady conduction mode is predominant to the heat transfer, the behavior of the time- and surface-averaged Nusselt number has the decaying pattern with increasing |α| for all gap spacings considered in this study. 相似文献
198.
Jungyol Jo Hyoshik Choi Junho Yun Haemi Kim Ogweon Seo Byeonggon Lee 《Thin solid films》2009,517(23):6337-1923
We developed a new method to realize enhancement-mode zinc oxide (ZnO) thin-film transistors (TFT) by metalorganic chemical vapor deposition (MOCVD). We used growth interruptions during MOCVD to encourage complete oxidation of deposited ZnO film, where diethylzinc and oxygen were used as sources. With this method, turn-off characteristics were significantly improved, and threshold voltage was shifted to positive voltages. ZnO TFTs grown at 450 °C showed 107 on/off ratio with 18 cm2/V s mobility, and + 5 V threshold voltage. Our data support that the surface layer is also important in determining ZnO TFT characteristics. 相似文献
199.
This study was designed to compare the effectiveness and applicability of the Petrifilm plate method with the Association of Official Analytical Chemists' (AOAC) standard aerobic count method and violet red bile agar method for meat products. The comparison was carried out using 303 meat samples collected from various retailers: 110 pork samples, 87 chicken samples, and 107 beef samples. In the comparison of the correlation coefficient (R) between the conventional method and the Petrifilm plate method by a linear regression analysis, the correlation coefficient in total microorganisms was 0.99, 0.95, and 0.94 in pork, beef, and chicken samples, respectively. The correlation coefficient in coliform count was 0.83, 0.96, and 0.81 in pork, beef, and chicken samples, respectively. Based on the high correlation in the total microorganism count, it might be possible to replace the conventional methods with the Petrifilm plate method. For coliform counts, the Petrifilm plate method also showed a generally high correlation coefficient, except for pork samples, which are more subject to contamination. The Petrifilm plate method was simpler and less time-consuming in sample preparation and, in procedures, faster than the conventional method. These results suggested that the 3M Petrifilm plate method could replace the conventional methods in the analysis of microorganism contamination measurement in meat products. 相似文献
200.
The inward approach in the design of control systems is introduced. This approach differs from the root-locus and the Bode-plot methods in that it involves first searching for an overall transfer function to meet design specifications and then computing the required compensator. The method is simple and straightforward and can easily be carried out with the aid of a digital computer simulator program 相似文献