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Chansong Kim,Jin Woong Lee,허준혁,Cheolhyun Park,Dai-Hwan Kim,Gyu Sung Yi1,Ho Chang Kang,Hyun Suk Jung,Hyunjung Shin,Jung Heon Lee 한국생체재료학회 2022 생체재료학회지 Vol.26 No.1
Background: A considerable number of studies has been carried out to develop alloplastic bone graft materials such as hydroxyapatite (HAP) that mimic the hierarchical structure of natural bones with multiple levels of pores: macro-, micro-, and nanopores. Although nanopores are known to play many essential roles in natural bones, only a few studies have focused on HAPs containing them; none of those studies investigated the functions of nanopores in biological systems. Method: We developed a simple yet powerful method to introduce nanopores into alloplastic HAP bone graft materials in large quantities by simply pressing HAP nanoparticles and sintering them at a low temperature. Results: The size of nanopores in HAP scaffolds can be controlled between 16.5 and 30.2 nm by changing the sintering temperature. When nanopores with a size of ~ 30.2 nm, similar to that of nanopores in natural bones, are introduced into HAP scaffolds, the mechanical strength and cell proliferation and differentiation rates are significantly increased. The developed HAP scaffolds containing nanopores (SNPs) are biocompatible, with negligible erythema and inflammatory reactions. In addition, they enhance the bone regeneration when are implanted into a rabbit model. Furthermore, the bone regeneration efficiency of the HAP-based SNP is better than that of a commercially available bone graft material. Conclusion: Nanopores of HAP scaffolds are very important for improving the bone regeneration efficiency and may be one of the key factors to consider in designing highly efficient next-generation alloplastic bone graft materials.
( Jing Yi ),( Bin Dong ),( Yong Gang Xue ),( Ning Li ),( Peng Gao ),( Yu Xin Zhao ),( Ling Ling Dai ),( Xiao Hu Dai ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.2
Microbial community shifts, associated with performance data, were investigated in an anaerobic batch digester treating high-solid food waste under mesophilic conditions using, a combination of molecular techniques and chemical analysis methods. The batch process was successfully operated with an organic removal efficiency of 44.5% associated with a biogas yield of 0.82 L/g VSremoval. Microbial community structures were examined by denaturing gel gradient electrophoresis. Clostridium and Symbiobacterium organisms were suggested to be mainly responsible for the organic matter catabolism in hydrolysis and acidogenesis reactions. The dynamics of archaeal and methanogenic populations were monitored using real-time PCR targeting 16S rRNA genes. Methanosarcina was the predominant methanogen, suggesting that the methanogenesis took place mainly via an aceticlastic pathway. Hydrogenotrophic methanogens were also supported in high-solid anaerobic digestion of food waste through syntrophism with syntrophic bacterium. Microbial community shifts showed good agreement with the performance parameters in anaerobic digestion, implying the possibility of diagnosing a high-solid anaerobic digestion process by monitoring microbial community shifts. On the other hand, the batch results could be relevant to the start-up period of a continuous system and could also provide useful information to set up a continuous operation.
李達兩 ( Dai Woo Yi ) 한국교육철학회 2012 교육철학 Vol.47 No.-
The proportion of teachers in education is essential. The purpose of this study is a critical discussion for the Jeong, Beom-Mo`s view of teachers. Jeong, Beom-Mo insisted that teacher is an engineering artist in his representative book Education and Science of Education. This book was published in 1974, preface was written in 1968, Spring conference of The Korean Society for the Study of Education` held in 2007, he insisted that teacher is a craftsman in his keynote speech titled to "Power of Eucation", Eventually, he has seen the teacher as an engineer. This point of view is derived from the concept of education that education is planned change of human behavior, In this concept of education, education is a science, therefore methodological aspects are emphasized in education. In order to overcome the methodology syndrome and view of teacher as an engineer in education, must be seen teacher as a living curriculum.
Research on Granular Computing Approach in Rough Set
Jin Dai,Feng Hu,Yi Yan 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.6
Granulation of information appears in many areas, such as machine learning, evidence theory, and data mining. Granular computing is the core research field in granulation of information. It is an effective tool for complex problem, massive data mining and fuzzy information processing. In the basis of principle of granularity, we aim to study the granular decomposing method in granules space based on rough set. Moreover, the criteria conditions for attribution necessity and attribute reduction are proposed. Finally, the corresponding equivalence is proved to traditional rough set theory. It will lay the foundation for attribute reduction under the granular representation in rough set.
Burial depth of anode affected the bacterial community structure of sediment microbial fuel cells
Yi-cheng Wu,Hong-jie Wu,Hai-yan Fu,Zhineng Dai,Ze-jie Wang 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.6
Sediment microbial fuel cells (SMFCs) are attractive devices to in situ power environmental monitoring sensors and bioremediate contaminated soils/sediments. Burial depth of the anode was verified to affect the performance of SMFCs. The present research evaluated the differences in microbial community structure of anodic biofilms located at different depth. It was demonstrated that both microbial diversity and community structure of anodic biofilms were influenced by the depth of anode location. Microbial diversity decreased with increased anodic depth. The number of the operational taxonomic units (OTUs) was determined as 1438 at the anode depth of 5 cm, which reduced to 1275 and 1005 at 10 cm and 15 cm, respectively. Cluster analysis revealed that microbial communities of 5 cm and 10 cm were clustered together, separated from the original sediment and 15 cm. Proteobacteria was the predominant phylum in all samples, followed by Bacteroidetes and Firmicutes. Beta- and Gamma-proteobacteria were the most abundant classes. A total of 23 OTUs showed high identity to 16S rRNA gene of exoelectrogens such as Geobacter and Pseudomonas. The present results provided insights into the effects of anode depth on the performance of SMFC from the perspectives of microbial community structure.
Dai, Kaoshan,Sheng, Chao,Zhao, Zhi,Yi, Zhengxiang,Camara, Alfredo,Bitsuamlak, Girma Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.1
The use of wind energy resources is developing rapidly in recent decades. There is an increasing number of wind farms in high wind-velocity areas such as the Pacific Rim regions. Wind turbine towers are vulnerable to tropical cyclones and tower failures have been reported in an increasing number in these regions. Existing post-disaster failure case studies were mostly performed through forensic investigations and there are few numerical studies that address the collapse mode simulation of wind turbine towers under strong wind loads. In this paper, the wind-induced failure analysis of a conventional 65 m hub high 1.5-MW wind turbine was carried out by means of nonlinear response time-history analyses in a detailed finite element model of the structure. The wind loading was generated based on the wind field parameters adapted from the cyclone boundary layer flow. The analysis results indicate that this particular tower fails due to the formation of a full-section plastic hinge at locations that are consistent with those reported from field investigations, which suggests the validity of the proposed numerical analysis in the assessment of the performance of wind-farms under cyclonic winds. Furthermore, the numerical simulation allows to distinguish different failure stages before the dynamic collapse occurs in the proposed wind turbine tower, opening the door to future research on the control of these intermediate collapse phases.
Kinematics/statics analysis of a novel serial-parallel robotic arm with hand
Yi Lu,Zhuohong Dai,Nijia Ye,Peng Wang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10
A robotic arm with fingered hand generally has multi-functions to complete various complicated operations. A novel serial-parallel roboticarm with a hand is proposed and its kinematics and statics are studied systematically. A 3D prototype of the serial-parallel roboticarm with a hand is constructed and analyzed by simulation. The serial-parallel robotic arm with a hand is composed of an upper 3RPSparallel manipulator, a lower 3SPR parallel manipulator and a hand with three finger mechanisms. Its kinematics formulae for solving thedisplacement, velocity, acceleration of are derived. Its statics formula for solving the active/constrained forces is derived. Its reachableworkspace and orientation workspace are constructed and analyzed. Finally, an analytic example is given for solving the kinematics andstatics of the serial-parallel robotic arm with a hand and the analytic solutions are verified by a simulation mechanism.