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161.
Kyoung Bin Lee Jin Soo Park Myung Do Oh Sung Joon Bae Shin Do Kim 《Journal of Mechanical Science and Technology》2014,28(7):2677-2686
This study measured and estimated the subway vent shaft air flow rate induced by moving trains in the tunnel. This work estimated the flow rate via the tunnel structure and train movement to determine the quantitative effect of vent shafts as air purification systems of natural ventilation to improve the air quality management of a subway. The amount of air suctioned into the tunnel is significantly larger than that vented from the tunnel. Thus, placing vent shafts near subway stations is desirable for natural ventilation systems. Experimental approaches to measure train-induced flow rates have not yet been published. Results of this study provide useful fundamental data to study the natural ventilation in a subway. Therefore, this study suggested the significant design factors required to control indoor air quality in a subway. 相似文献
162.
Nanocrystalline Ni ferrite thin film was prepared by electrospray deposition technique and characterized by different analytical techniques at different annealing temperatures. All these films were studied by photovoltaic‐assisted water electrolysis system for solar to hydrogen production efficiency measurement. Highly dense and uniform surface morphology was observed in as‐deposited film, which changed into agglomerated nanocrystalline grains of irregular size and shape with change in annealing temperature. The X‐ray photoelectron spectroscopy study showed that the as‐deposited film was a mixture of an oxyhydroxide form of iron and an Ni2O3 form of nickel, whereas it changed into ferrite phase with change in annealing temperature. The as‐deposited film was observed to be of amorphous phase, which changed to crystalline cubic spinel structure with change in annealing temperature. The solar to hydrogen production efficiency was found to increase in a film with an increase in annealing temperature. The film annealed at 500°C showed a high solar to hydrogen production efficiency (8.29%) with constant performance of up to initial 500 h. Thereafter, the performance slowly declined by 11% when up to 1000 h. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
163.
Biased discriminant analysis (BDA), which extracts discriminative features for one-class classification problems, is sensitive to outliers in negative samples. This study focuses on the drawback of BDA attributed to the objective function based on the arithmetic mean in one-class classification problems, and proposes an objective function based on a generalized mean. A novel method is also presented to effectively maximize the objective function. The experimental results show that the proposed method provides better discriminative features than the BDA and its variants. 相似文献
164.
Keeman Kim Hyoung Chan Kim Sangjun Oh Young Seok Lee Jun Ho Yeom Kihak Im Gyung-Su Lee George Neilson Charles Kessel Thomas Brown Peter Titus 《Fusion Engineering and Design》2013,88(6-8):488-491
As the ITER is being constructed, there is a growing anticipation for an earlier realization of fusion energy, so called fast-track approach. Korean strategy for fusion energy can be regarded as a fast-track approach and one special concept discussed in this paper is a two-stage development plan. At first, a steady-state Korean DEMO Reactor (K-DEMO) is designed not only to demonstrate a net electricity generation and a self-sustained tritium cycle, but also to be used as a component test facility. Then, at its second stage, a major upgrade is carried out by replacing in-vessel components in order to show a net electric generation on the order of 300 MWe and the competitiveness in cost of electricity (COE). The major radius is designed to be just below 6.5 m, considering practical engineering feasibilities. By using high performance Nb3Sn-based superconducting cable currently available, high magnetic field at the plasma center above 8 T can be achieved. A design concept for TF magnets and radial builds for the K-DEMO considering a vertical maintenance scheme, are presented together with preliminary design parameters. 相似文献
165.
Woo‐Il Baek Hem Raj Pant R. Nirmala Ki‐Taek Nam Hyun‐Ju Oh Hak‐Yong Kim 《Polymer International》2012,61(5):844-849
In the present study, the effect of adhesive on the morphology of different electrospun polymeric mats was investigated. The modification of two polymers, poly(methyl methacrylate) and poly(vinyl chloride), was carried out by blending the polymers with different amounts of poly(butyl acrylate) (PBA) adhesive to investigate the effect of different amounts of adhesive with heat hardener in hybrid mats. The introduction of various concentrations of PBA into different polymer solutions led to the formation of point‐bonded electrospun fibrous mats. Scanning electron microscopy images indicated that point‐bonded polymer/adhesive fibers were uniformly distributed throughout the mats. Fourier transform infrared spectrometry, contact angle measurements and thermogravimetric analysis were used to study the different properties of the hybrid mats. The tensile strength of the blended fibrous electrospun mats was increased effectively. This enhancement of the mechanical properties of the mats due to the presence of adhesive increases the number of potential applications of the electrospun mats, especially for mechanically weak polymers. Copyright © 2012 Society of Chemical Industry 相似文献
166.
Kyung Yoen Won Young Soo Kim Kyeong Keun Oh 《Korean Journal of Chemical Engineering》2012,29(10):1341-1346
Cellulose rich barley straw, which has a glucan content of 62.5%, followed by dilute acid pretreatment, was converted to bioethanol by simultaneous saccharification and fermentation (SSF). The optimum fractionation conditions for barley straw were an acid concentration of 1% (w/v), a reaction temperature of 158 °C and a reaction time of 15 min. The maximum saccharification of glucan in the fractionated barley straw was 70.8% in 72 h at 60 FPU/gglucan, while the maximum digestibility of the untreated straw was only 18.9%. With 6% content WIS (water insoluble solid) for the fractionated barley straw, 70.5 and 83.2% of the saccharification yield were in SHF and SSF (representing with glucose equivalent), respectively, and a final ethanol concentration of 18.46 g/L was obtained under the optimized SSF conditions: 34 °C with 15 FPU/g-glucan enzyme loading and 1 g dry yeast cells/L. The results demonstrate that the SSF process is more effective than SHF for bioethanol production by around 18%. 相似文献
167.
168.
Hyun-Wung Kwon Suk-Yoon Hong Dae-Kyun Oh Jihoon Lee Doo-Jin Hwang Ok-Sam Kim Jee-Hun Song 《Journal of Mechanical Science and Technology》2014,28(9):3405-3410
Energy flow analysis (EFA) can be used effectively to predict structural vibration in the medium-to-high frequency ranges. In this study, the energy flow finite element method (EFFEM), based on EFA, was used to predict the vibrations of a reinforced cylindrical structure in water. The predicted results of the vibrational energy density for the structure were compared with corresponding experimental results. The structure was divided into several subsystems in the experiment, with several accelerometers attached to each subsystem. The input power excited into the experimental structure was measured using an impedance-head adhered to an exciter. Measured input power was used to predict vibration of the reinforced cylindrical structure by EFFEM in water for comparing experimental and numerical results. A comparison between the experimental and predicted results for the vibrational energy density showed that EFFEM was an effective tool for predicting structural vibration. 相似文献
169.
Xin Jin Chang‐Sei Kim Guy A. Dumont J. Mark Ansermino Jin‐Oh Hahn 《International Journal of Adaptive Control and Signal Processing》2017,31(2):240-254
This paper presents a semi‐adaptive control approach to closed‐loop medication infusion problems. The rationale underlying this approach is to design a controller that can adapt model parameters with a large impact on the model's fidelity while fixing the remaining parameters at nominal values. In this paper, a control‐oriented model for this purpose is derived via system identification and sensitivity analysis of a low‐order model capturing the direct dose‐response relationship Using the model thus derived, a model‐reference adaptive controller and a composite adaptive controller are designed and compared with each other. In‐silico simulation results using remifentanil's effect on respiratory rate as an example indicate that both controllers can regulate the output at commanded set points. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
170.
Jeongseok Oh Seokswoo Cho Bumsik Ham 《Journal of Mechanical Science and Technology》2017,31(12):5761-5767
In a polyethylene boat, a transom pod is subjected to repeated thrust forces generated by an outboard motor. The structural design of the transom pod for the outboard motor must be considered because it is subjected to cyclic bending moments causing thrust forces of the outboard motor. We designed a transom pod reinforced with aluminum alloy plate inside the transom pod in a polyethylene boat and obtained an optimal thickness of the Al alloy plate to ensure the transom pod durability. We then performed a structural analysis for the transom pod reinforced with Al alloy plate and estimated the fatigue life using modified Goodman diagram. The optimal thickness of Al alloy plate was 7 mm. 相似文献