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141.
Sang Hyun Park Younghwan Jin Kyunghan Ahn In Chung Chung-Yul Yoo 《Journal of Electronic Materials》2017,46(2):848-855
The structural and electrical characteristics of Ag/Ni bilayer metallization on polycrystalline thermoelectric SnSe were investigated. Two difficulties with thermoelectric SnSe metallization were identified for Ag and Ni single layers: Sn diffusion into the Ag metallization layer and unexpected cracks in the Ni metallization layer. The proposed Ag/Ni bilayer was prepared by hot-pressing, demonstrating successful metallization on the SnSe surface without interfacial cracks or elemental penetration into the metallization layer. Structural analysis revealed that the Ni layer reacts with SnSe, forming several crystalline phases during metallization that are beneficial for reducing contact resistance. Detailed investigation of the Ni/SnSe interface layer confirms columnar Ni-Sn intermetallic phases [(Ni3Sn and Ni3Sn2) and Ni5.63SnSe2] that suppress Sn diffusion into the Ag layer. Electrical specific-contact resistivity (5.32 × 10?4 Ω cm2) of the Ag/Ni bilayer requires further modification for development of high-efficiency polycrystalline SnSe thermoelectric modules. 相似文献
142.
Juhee Ahn Hyeon-Yong Lee Lynn Knipe V. M. Balasubramaniam 《Food science and biotechnology》2014,23(5):1477-1481
Effects of surface pasteurization on inactivation of Listeria innocua were investigated. Surface temperature, monitored during post-packaging pasteurization, was used to predict the lethality of L. monocytogenes. Temperatures reached 70°C for lean and fat sausages within 9 min of treatment. An inoculation study validated the efficacy of post-processing and the thermal lethality of L. monocytogenes. Pre-cooked sausage and ham, inoculated with approximately 107 CFU/cm2 of L. innocua, were heated to a surface temperature of 70°C. Numbers of L. innocua were reduced by 7 log on surface-inoculated sausage. Guidelines for safe, ready-to-eat meat products are provided for small scale meat processors. 相似文献
143.
Seonyeob Kim Ji Young Jung Han Ho Song Seung Jin Song Kook Young Ahn Sang Min Lee Young Duk Lee Sanggyu Kang 《International Journal of Hydrogen Energy》2014
In a previous study, a new hybrid system of molten carbonate fuel cell (MCFC) and homogeneous charge compression ignition (HCCI) engine was developed, where the HCCI engine replaces the catalytic burner and produces additional power by using the left-over heating values from the fuel cell stack. In the present study, to reduce the additional cost and footprint of the engine system in a hybrid configuration, the possibility of engine downsizing is investigated by using two strategies, i.e. the use of a turbocharger and the use of high geometric compression ratio for the engine design, both of which are to increase the density of the intake charge and thus the volumetric efficiency of the engine. Combining these two strategies, we suggest a new engine design with ∼60% of displacement volume of the original engine. In addition, operating strategies are developed to run the new hybrid system under part load conditions. It is successfully demonstrated that the system can operate down to 65% of the power level of the design point, while the system efficiency remains almost unchanged near 63%. 相似文献
144.
Ho Lee Taehee Kim Woojong Sim Saehoon Kim Byungki Ahn Taewon Lim Kwonpil Park 《Korean Journal of Chemical Engineering》2011,28(2):487-491
During the operation of a PEMFC, the polymer membrane is degraded by electrochemical reactions and mechanical stresses. We
investigated the effects of repeated electrochemical and mechanical degradations in a membrane. For mechanical degradation,
the membrane and MEA were repeatedly subjected to wet/dry cycles; for electrochemical degradation, the cell was operated under
open-circuit voltage (OCV)/low-humidity conditions. The repeated wet/dry cycles led to a decrease in the mechanical strength
of the membrane. When the MEA was degraded electrochemically, repeated wet/dry cycling resulted in the formation of pinholes
in the membrane. In the case of different MEAs that were first degraded electrochemically, the extents of their hydrogen crossover
currents increased due to repeated wet/dry cycling being different. Therefore, these results indicated that the membrane durability
could be evaluated by these methods of repeated electrochemical degradation and wet/dry cycles. 相似文献
145.
146.
Hak-Yoon Kim Insoo Choi Sang Hyun Ahn Seung Jun Hwang Sung Jong Yoo Jonghee Han Jihyun Kim Hansoo Park Jong Hyun Jang Soo-Kil Kim 《International Journal of Hydrogen Energy》2014
Electrochemical reduction of CO2 to HCOOH was performed on a Sn electrode using a proton exchange membrane-embedded electrolysis cell. The effects of reaction conditions such as catholyte and anolyte types, reduction potential, catholyte pH, and reaction temperature on the amount of HCOOH and its faradaic efficiency were investigated. Four different electrolytes (KOH, KHCO3, KCl, KHSO4) were chosen as the candidate catholyte and anolyte; the most suitable electrolyte was chosen by monitoring the amount of HCOOH and faradaic efficiency. The effect of the pH of the selected catholyte on the conversion of CO2 to HCOOH was also investigated. In addition, the reaction temperature was varied and its effect was studied. From the observations made, we determined the optimal reaction conditions for the production of HCOOH via the electrochemical reduction of CO2 by a systematic approach. 相似文献
147.
148.
Existing models of causal induction primarily rely on the contingency between the presence and the absence of a causal candidate and an effect. Yet, classification of observations into these four types of covariation data may not be straightforward because (a) most causal candidates, in real life, are continuous with ambiguous, intermediate values and because (b) effects may unfold after some temporal lag, providing ambiguous contingency information. Although past studies suggested various reasons why ambiguous information may not be used during causal induction, the authors examined whether learners spontaneously use ambiguous information through a process called causal assimilation. In particular, the authors examined whether learners willingly place ambiguous observations into one of the categories relevant to the causal hypothesis, in accordance with their current causal beliefs. In Experiment 1, people's frequency estimates of contingency data reflected that information ambiguous along a continuous quantity dimension was spontaneously categorized and assimilated in a causal induction task. This assimilation process was moderated by the strength of the upheld causal hypothesis (Experiment 2), could alter the overall perception of a causal relationship (Experiment 3), and could occur over temporal sequences (Experiment 4). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
149.
Yu-Jin Hong Ig-Jae Kim Sang Chul Ahn Hyoung-Gon Kim 《Simulation Modelling Practice and Theory》2010,18(4):446-455
We propose a new method to recognize a user’s activities of daily living with accelerometers and RFID sensor. Two wireless accelerometers are used for classification of five human body states using decision tree, and detection of RFID-tagged objects with hand movements provides additional instrumental activity information. Besides, we apply our activity recognition module to the health monitoring system. We derive linear regressions for each activity by finding the correlations between the attached accelerometers and the expended calories calculated from gas exchange analyzer under different activities. Finally, we can predict the expended calories more efficiently with only accelerometer sensor depend on the recognized activity. We implement our proposed health monitoring module on smart phones for better practical use. 相似文献
150.
Bing SunZhixing Chen Hyun-Soo KimHyojun Ahn Guoxiu Wang 《Journal of power sources》2011,196(6):3346-3349
MnO/C core-shell nanorods were synthesized by an in situ reduction method using MnO2 nanowires as precursor and block copolymer F127 as carbon source. Field emission scanning electron microscopy and transmission electron microscopy analysis indicated that a thin carbon layer was coated on the surfaces of the individual MnO nanorods. The electrochemical properties were evaluated by cyclic voltammetry and galvanostatic charge-discharge techniques. The as-prepared MnO/C core-shell nanorods exhibit a higher specific capacity than MnO microparticles as anode material for lithium ion batteries. 相似文献