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KaiFeng StephenJ.Lombardo,KaiFeng 한양대학교 세라믹연구소 2002 Journal of Ceramic Processing Research Vol.3 No.3
The decomposition and sintering of calcium carbonate were examined in a combined dilatometer and mass spectrometer apparatus. Carbon dioxide from the decomposition reaction is evolved from 600-1000oC for heating rates of 1-15 K minute-1. During the decomposition reaction, an initial period of shrinkage of 2-4% was observed. Above 1100oC, a second period of shrinkage of 2-4% occurred, which is attributed to the sintering of the calcium oxide produced from the decomposition reaction. Kinetic rate parameters for the decomposition, initial stage of shrinkage, and relative density were analyzed by reaction and sintering models using integral methods of analysis. Both the decomposition and relative density were reasonably well described with an activation energy of 115-120 kJ mol-1 for the full range of conversion over a wide range of temperature. The initial stage of shrinkage was described by a diffusion mechanism with an activation energy of 225 kJ mol-1.
Effect of Light Intensity on Close-Range Photographic Imaging Quality and Measurement Precision
Kaifeng Ma,Ximin Cui,Guiping Huang,Debao Yuan 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.2
To test the effectiveness of flash intensity in digital close-range photogrammetry, test methods for the light intensity adjustment of a ring-flash on close-range photographic imaging quality and measuring precision were researched respectively. First, according to the efficiency of the flash, the imaging characteristics, and the gray distribution of the mark points of the image, the identified method of the image gray value for subjective visual analysis was presented, and a quality standard for the close-range photographic image was provided. Then, as a precondition to obtaining the best image quality, based on the estimation theory governing measurement adjustment precision, the changes in measuring precision under conditions of different light intensity and different photographic distances were analysed, and the relationships between measurement precision and light intensity, or photographic distance, were obtained. Finally, the globally optimal imaging quality and measurement precision for any given light intensity were quantified. Experimental results indicated that the root mean square (RMS) errors of the measurement adjustment precision were 0.028 mm, 0.039 mm, and 0.085 mm: the RMS errors in the measuring precision and the corresponding coordinate repeatability were 0.038 mm, 0.053 mm, and 0.118 mm. The best imaging quality was achieved at photographic distances of 3 m, 5 m, and 7 m, with corresponding output light intensities of 1/64, 1/32, and 1/16 under certain conditions, respectively. This can satisfy the precision requirements for large-scale coordinate measurement, and provides a basis for formulating a reasonable light intensity output from a ring-flash in the digital close-range photogrammetry.
Microbial composition in different gut locations of weaning piglets receiving antibiotics
Li, Kaifeng,Xiao, Yingping,Chen, Jiucheng,Chen, Jinggang,He, Xiangxiang,Yang, Hua Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.1
Objective: The aim of this study was to examine shifts in the composition of the bacterial population in the intestinal tracts (ITs) of weaning piglets by antibiotic treatment using high-throughput sequencing. Methods: Sixty 28-d-old weaning piglets were randomly divided into two treatment groups. The Control group was treated with a basal diet without antibiotics. The Antibiotic group's basal diet contained colistin sulfate at a concentration of 20 g per ton and bacitracin zinc at a concentration of 40 g per ton. All of the pigs were fed for 28 days. Then, three pigs were killed, and the luminal contents of the jejunum, ileum, cecum, and colon were collected for DNA extraction and high-throughput sequencing. Results: The results showed that the average daily weight gain of the antibiotic group was significantly greater (p<0.05), and the incidence of diarrhea lower (p>0.05), than the control group. A total of 812,607 valid reads were generated. Thirty-eight operational taxonomic units (OTUs) that were found in all of the samples were defined as core OTUs. Twenty-one phyla were identified, and approximately 90% of the classifiable sequences belonged to the phylum Firmicutes. Forty-two classes were identified. Of the 232 genera identified, nine genera were identified as the core gut microbiome because they existed in all of the tracts. The proportion of the nine core bacteria varied at the different tract sites. A heat map was used to understand how the numbers of the abundant genera shifted between the two treatment groups. Conclusion: At different tract sites the relative abundance of gut microbiota was different. Antibiotics could cause shifts in the microorganism composition and affect the composition of gut microbiota in the different tracts of weaning piglets.
Haeil Jung(Haeil Jung),Ki Woong Cho(Ki Woong Cho),Kaifeng Yang(Kaifeng Yang),Sun Young Kim(Sun Young Kim),Yihong Liu(Yihong Liu) 한국학술연구원 2023 Korea Observer Vol.54 No.1
COVID-19 has spread quickly worldwide, presenting unprecedented challenges to countries all over the globe. To understand how different countries have responded to COVID-19 during the early stage of the outbreak, we develop a comprehensive research framework drawing on the literature on wicked problems. Specifically, we comparatively investigate the government responses of the United States, China, and South Korea and examine why and how these countries have adopted and implemented various strategies authoritative, collaborative, and competitive — —depending on their policy environment. Although scholars have argued that collaborative strategies are the preferred approach to dealing with wicked problems, it is found that the most applicable, implementable, and effective strategies vary according to the country's cultural, economic, and political contexts. In addition, the urgency and timing of the crisis may affect the choice of appropriate strategies. Our findings can provide lessons for public administration and policy to cope with other wicked problems.
Calculating Wind Variability Costs with Considering Ramping Costs of Conventional Power Plants
Xuemei Dai,Kaifeng Zhang,Jian Geng,Ying Wang,Kun Yuan 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.3
Due to the variability of the wind power, conventional power plants are required to ramp more frequently to mitigate the imbalance of generation and supply, which increase the total cost of power systems. The increase of the cost is termed the “variability cost” of wind power. Generally, it includes the additional ramping cost, reserve cost and fuel cost of conventional plants. In this paper, we propose an alternative scenario construction method to calculate the “variability cost” of wind power from the viewpoint of the power system schedule. Firstly, in the alternative scenario, a new energy proxy with zero wind variability costs is constructed. Then, a unit commitment optimization model considering ramping costs is developed. The operation costs of power systems under two scenarios (alternative one and real one) are calculated and the diff erence between two costs is the variability cost. Furthermore, we apply the proposed method to calculate the variability costs of the wind farm cluster. The simulations show that the variability cost increases with higher penetration and higher variability of wind power. Meanwhile, it is found that the variability cost of the wind farm cluster as a whole is lower than the sum of variability costs of each wind farm.
Probabilistic fatigue assessment of rib-to-deck joints using thickened edge U-ribs
Junlin Heng,Kaifeng Zheng,Sakdirat Kaewunruen,Jin Zhu,Charalampos Baniotopoulos 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.6
Fatigue cracks of rib-to-deck (RD) joints have been frequently observed in the orthotropic steel decks (OSD) using conventional U-ribs (CU). Thickened edge U-rib (TEU) is proposed to enhance the fatigue strength of RD joints, and its effectiveness has been proved through fatigue tests. In-depth full-scale tests are further carried out to investigate both the fatigue strength and fractography of RD joints. Based on the test result, the mean fatigue strength of TEU specimens is 21% and 17% higher than that of CU specimens in terms of nominal and hot spot stress, respectively. Meanwhile, the development of fatigue cracks has been measured using the strain gauges installed along the welded joint. It is found that such the crack remains almost in semi-elliptical shape during the initiation and propagation. For the further application of TEUs, the design curve under the specific survival rate is required for the RD joints using TEUs. Since the fatigue strength of welded joints is highly scattered, the design curves derived by using the limited test data only are not reliable enough to be used as the reference. On this ground, an experiment-numerical hybrid approach is employed. Basing on the fatigue test, a probabilistic assessment model has been established to predict the fatigue strength of RD joints. In the model, the randomness in material properties, initial flaws and local geometries has been taken into consideration. The multiple-site initiation and coalescence of fatigue cracks are also considered to improve the accuracy. Validation of the model has been rigorously conducted using the test data. By extending the validated model, large-scale databases of fatigue life could be generated in a short period. Through the regression analysis on the generated database, design curves of the RD joint have been derived under the 95% survival rate. As the result, FAT 85 and FAT 110 curves with the power index m of 2.89 are recommended in the fatigue evaluation on the RD joint using TEUs in terms of nominal stress and hot spot stress respectively. Meanwhile, FAT 70 and FAT 90 curves with m of 2.92 are suggested in the evaluation on the RD joint using CUs in terms of nominal stress and hot spot stress, respectively.
Hongyou Li,Kaifeng Huang,Hanmei Du,Hongling Wang,Xin Chen,Shibin Gao,Hailan Liu,Moju Cao,Yanli Lu,Tingzhao Rong,Su-Zhi Zhang 한국식물학회 2016 Journal of Plant Biology Vol.59 No.6
Gro/Tup1 proteins act as negative transcriptional regulators and play crucial roles in many growth and developmental processes in a wide range of organisms. However, our understanding of Gro/Tup1 protein functions in plants is confined to the model plant Arabidopsis. Here, 11 Gro/Tup1 genes, which were characterized by the typical LisH and WD40 repeat domains, were identified in maize through a genome-wide survey. A phylogenetic analysis revealed that maize Gro/Tup1 proteins could be divided into three subfamilies, in which members shared similar protein and gene structures. The predicted maize Gro/Tup1 genes were distributed on seven chromosomes and segmental duplication contributed to their expansion. Many predicted cis-elements associated with hormones, biotic- or abioticstress responses, meristem and seed development, and circadian rhythms, were found in their putative promoter regions. A potential associated protein analysis identified a large number of candidates, including transcription factors, chromatin-modifying enzymes, protein kinases, and ubiquitinconjugating enzymes. An expression profile derived from the RNA-seq data indicated that Gro/Tup1 genes in maize were widely expressed in various organs and tissues. Quantitative real-time PCR revealed that these genes responded to at least one hormone or abiotic stress, either in roots or in shoots. Our study provides useful information on the Gro/Tup1 genes in maize and will facilitate the further functional validation of these genes in growth and development, hormone responses, and biotic- or abiotic-stress resistance.
Novel magnetorheological brake with self-protection and water cooling for elevators
Hui Huang,Shumei Chen,Kaifeng Chen 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.5
This study aims to design a magnetorheological (MR) brake with self-protection and heat dissipation functions for elevators. Using permanent magnet system technology, the MR brake can not only form a double magnetic field with excitation coils to improve braking torque under normal operation but also provide braking torque for protection in case of power failure. In addition, a cooling channel is designed in the braking shaft of the MR brake to ensure effective heat dissipation of the MR fluid. In this work, the structure, material, and magnetic circuit of the MR brake is first developed. Then, finite element, magnetic field, and thermal field analyses are conducted on the brake. Finally, a prototype of the brake is produced, and its performance is tested. Results show that the braking torque, especially the self-protection function, meets the demands of the elevator; the increase in temperature during braking is minor; and the noise level is low .
Feng Xiaona,Wang Kaifeng,Yang Ting,Liu Yanhui,Wang Xiaodong 한국유전학회 2022 Genes & Genomics Vol.44 No.4
Background: We have clarified the role of miR-382-3p in chronic thromboembolic pulmonary hypertension (CTEPH), but what is less clear lies in its upstream regulatory mechanism. Objective: To explore the regulation mechanism of GAS5/miR-382-3p axis on CTEPH. Methods: In vitro, we constructed cell models by treating Pulmonary Artery Smooth Muscle Cells (PASMCs) with platelet-derived growth factor-BB (PDGF-BB). The effects of different concentrations of PDGF-BB on the activity of PASMCs were tested by cell counting kit-8 (CCK-8). The upstream lncRNA of miR-382-3p was screened and confirmed through bioinformatics analysis, RNA pull-down, quantitative reverse transcription polymerase chain reaction (qRT-PCR), dual luciferase reporter gene and RNA immunoprecipitation assays. The effects of GAS5/miR-382-3p axis on the viability, migration, and expressions of autophagy- and angiogenesis-related proteins were confirmed by rescue experiments (CCK-8, wound healing and western blot). In vivo, animal models by perfusing autologous blood vessels, the effects of GAS5 overexpression or silencing on the expressions of miR-382-3p, angiogenesis- and autophagy-related genes, mean pulmonary arterial pressure (mPAP) and pulmonary artery wall were determined by biological signal acquisition system, hematoxylin-eosin staining, qRT-PCR and western blot. Results: PDGF-BB dose-dependently promoted PASMCs viability. XIST and GAS5 expressions in PASMCs were affected by the concentration of PDGF-BB, but only GAS5 can be pulled down by miR-382-3p probe. GAS5 targeted miR-382-3p to inhibit the viability and migration of PAMSCs, mPAP in CTEPH rats, pulmonary artery wall thickening and angiogenesis, and promote autophagy. Conclusions: GAS5/miR-382-3p axis is involved in the regulation of pulmonary artery remodeling and autophagy in CTEPH.
Ying Zhao,Jinyu Shi,Kaifeng Wang,Binlin Wang,Chao He,Xiaogang Deng 한국자동차공학회 2023 International journal of automotive technology Vol.24 No.1
A honeycomb sandwich battery box composed of high-strength steel outer layer, sandwich aluminum alloy honeycomb and inner layer is proposed. Firstly, the expressions of platform stress, ultimate strain and equivalent elastic modulus of ‘Y’ honeycomb cell are derived based on deformation mechanism and energy principle under quasi-static compression, and then the relations among relative density, unit volume energy absorption and thickness coefficient are acquired. Based on above, the optimal thickness coefficient of honeycomb unit cell can be acquired by utilizing particle swarm optimization algorithm. Simultaneously, aluminum alloy honeycomb sample is made to verify the accuracy of finite element simulation and theoretical models under quasi-static compression. Subsequently, the optimal thicknesses of three layers are optimized with the constraint that the 1st mode frequency is more than 30 Hz. Finally, the mass of the optimized battery box decreases by 37.26 %, and its static performances increase more largely compared with traditional one.