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Dong, Yu Zhen,Choi, Hyoung Jin IEEE 2018 IEEE transactions on magnetics Vol.54 No.11
<P>Fe<SUB>3</SUB>O<SUB>4</SUB> was synthesized on the surface of poly(diphenylamine) (PDPA) via the co-precipitation method to form a PDPA/Fe<SUB>3</SUB>O<SUB>4</SUB>) composite, and the composite was used as the magnetorheological (MR materials. The microstructure and magnetic properties of the PDPA/Fe<SUB>3</SUB>O<SUB>4</SUB> composite were characterized by the transmission electron microscopy and vibrating sample magnetometer, respectively. The MR fluid was prepared by dispersing the PDPA/Fe<SUB>3</SUB>O<SUB>4</SUB> in silicone oil, and the rheological characteristics of it were measured via a rotational rheometer.</P>
Additive effect of rod-like magnetite/sepiolite composite particles on magnetorheology
Yu Zhen Dong,Wen Jiao Han,최형진 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.93 No.-
Rod-like magnetite/sepiolite nanocomposite particles were fabricated using a chemical co-precipitationprocess and introduced as an added ingredient in a carbonyl iron (CI)-based magnetorhologicalfluid(MRF). The morphologies of the composite particles and CI-magnetite/sepiolite mixture were observedby scanning electron microscopy. Two types of MRFs with and without magnetite/sepiolite additive werefabricated, and their MR behaviors and sedimentation stability were investigated using a rotationrheometer and an optical analyzer system of Turbiscan, respectively. The results showed that the additionof rod-like magnetite/sepiolite additives enhanced both the dispersion and MR properties of CI-basedMRF, making its potential application more promising.
Yu Zhen Dong,최형진 한국고분자학회 2018 Macromolecular Research Vol.26 No.8
Polymer-inorganic composite particles composed of poly(diphenylamine) (PDPA) and Fe3O4 were synthesized to fabricate a smart material that can respond to both electric and magnetic fields. PDPA was synthesized using a chemical oxidative polymerization process, and the PDPA/magnetite (PDPA/Fe3O4) composites were fabricated by loading Fe3O4 nanoparticles onto the surface of PDPA using a coprecipitation method. The surface roughness of the composites was larger than that of pure PDPA, and the composites exhibited paramagnetic properties with a saturation magnetization of 77.1 kA/m. An electrorheological (ER) and magnetorheological (MR) fluid was prepared by dispersing PDPA/Fe3O4 composites in silicone oil. An examination of the responses under an external electric or magnetic field revealed significant ER and MR characteristics.
Dong, Yu Zhen,Piao, Shang Hao,Zhang, Ke,Choi, Hyoung Jin Elsevier 2018 Colloids and surfaces. A, Physicochemical and engi Vol.537 No.-
<P><B>Abstract</B></P> <P>Magnetic CoFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles were successfully fabricated by a non-aqueous hydrothermal method and used as an additive in a micron-sized, carbonyl iron (CI) based-magnetorheological (MR) fluid to improve its dispersion stability and MR characteristics. The morphology and magnetic properties of CoFe<SUB>2</SUB>O<SUB>4</SUB> were demonstrated by using X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. The results showed that CoFe<SUB>2</SUB>O<SUB>4</SUB> was synthesized successfully with a nearly spherical morphology and excellent crystalline structure. The saturation magnetization (Ms) of the CoFe<SUB>2</SUB>O<SUB>4</SUB> was also about 74.4 emu/g. The CI MR fluid was prepared by dispersing 50wt% of CI particles in silicone oil, and the CI/CoFe<SUB>2</SUB>O<SUB>4</SUB> MR fluid was prepared by adding 0.1wt% of CoFe<SUB>2</SUB>O<SUB>4</SUB> nanoparticles to the CI MR fluid. The MR characteristics of both MR fluids were tested via a rotational rheometer at various magnetic field strengths. The CI/CoFe<SUB>2</SUB>O<SUB>4</SUB> MR fluid showed enhanced MR characteristics with higher yield stress, shear viscosity, and dynamic modulus than that of the CI MR fluid. Furthermore, the dispersion stability of both MR fluids were also investigated via a Turbiscan optical analyzer system, and these results showed that the sedimentation ratio after 24h had improved by about 21%.</P> <P><B>Graphical abstract</B></P> <P>Magnetic CoFe2O4 nanoparticles were successfully fabricated by a non-aqueous hydrothermal method and used as an additive in a micron-sized, carbonyl iron (CI) based-magnetorheological (MR) fluid. The magnetorheological characteristics and dispersion stabilities for two kinds of CI based-MR fluid with and without CoFe2O4 additives were investigated.</P> <P>[DISPLAY OMISSION]</P>
A Study on the Landscape Planning and Construction along the Yellow River in Shandong
( Dong Ming Yu ),( Yong Ji Piao ),( Zhen Wang ),( Juan Zhang ) 한국녹지환경디자인학회 2006 녹지환경학회지 Vol.2 No.1
Waterfront is the origin of human culture and the vivid district of ecology and landscape in a city. Yellow River is the mother river to Chinese people and also is one of the most complicated and difficultly managed rivers in the world. Based on the analysis of present situations of landscape planning and construction of Shandong Yellow River, some countermeasures are put forward in the paper.
3D implementation of push-out test in ABAQUS using the phase-field method
Xianbin Yu,Ronghui Wang,Chunguang Dong,Jianyi Ji,Xiaoxia Zhen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.4
The phase-field method (PFM) localizes the damaged and broken material in concrete with a phase-field order parameter d, successfully avoiding the description of nonsmooth crack surfaces, as well as the pre-setting and tracking of complex crack extension paths. However, most works have focused on 2D and simple 3D problems of non-reinforced concrete due to the high computational cost. A 3D PFM is implemented in the commercial finite element code ABAQUS to model damage and quasi-brittle fractures in composite beam concretes. The damage problem is implemented in the user subroutines UMAT and HETVAL on account of the similarity between the evolution law of the order parameter and the heat transfer law. In addition, a FORTRAN file is used to define the relationships among the material properties. Through this approach, modeling, computational task submission, and post-processing are completed in the GUI of ABAQUS, and the internal nonlinear algorithms are adopted directly. The accuracy of the modeling method is verified by comparing with two classical experimental data in the literature, and the maximum load data and load-displacement curve are well fitted. Moreover, a 3D numerical model for the push-out test of the composite beam is developed. Simulation results are consistent with the test results, such as the trend of the loaddisplacement curve, the damage pattern of the concrete, and the stress condition of the shear bolts. The parametric analysis shows that the compressive and tensile strengths of the shear bonds can significantly affect the load bearing capacity of composite beams, whereas the material parameters of concrete have a limited influence, consistent with the previous experience. The PFM has proven its ability to handle complex quasi-brittle fracture of concrete, and the present work can provide a reference for modeling concrete cracks in engineering structures.
Yan, Zhen,Ma, Yu Zhen,Liu, Dong jun,Cang, Ming,Wang, Rui,Bao, Shorgan Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.4
RNA interference (RNAi) is an acknowledged useful and effective tool to study gene function in various cells. Here, we suppressed the Connexin 43 (Cx 43) gene expression during in vitro development of ovine pre-implantation embryos using the RNAi method. The 353 bp Cx 43 double-stranded RNA was microinjected into in vitro fertilized ovine zygotes, and the levels of target mRNA and protein were investigated. Control groups included uninjected zygotes or those injected with RNase-free water. The dsRNA injection resulted in the specific reduction of Cx 43 transcripts as analyzed by quantitative real-time RT-PCR and decreased protein levels as shown by Western blot analysis at the blastocyst stage. Microinjection of Cx 43 dsRNA led to 20.3%, 21.7% and 34.5% blastocyst rates and 19.2%, 37.5% and 41.3% hatched blastocyst rates in Cx 43 dsRNA-injected, water-injected and uninjected groups, respectively. Then the RNAi could not significantly affect cell number and cell death rates of blastocysts. Therefore, suppression of Cx 43 dsRNA and proteins did not apparently affect the development potential of ovine pre-implantation embryos but may play a role in embryo quality. RNAi technology is a promising approach to study gene function in early ovine embryogenesis.
마이크로 지오메트리 방법을 이용한 크로스 드릴링/밀링 유닛 구동기어의 동력전달 최적화에 관한 연구
김동선(Dong-Seon Kim),진진(Zhen Qin),백권인(Gwon-In Beak),우위팅(Yu-Ting Wu),전남술(Nam-Sul Jeon),류성기(Sung Ki Lyu) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.4
A cross drilling/milling Unit is an important mechanical part which is widely used in many kinds of machining tool, and various gear trains with good accuracy and reliability features are widely used in power transmission systems. A study on a novel power transmission optimization method for driving gear trains in cross drilling/milling units is presented in this paper. A commercial program for gear system simulation, Romax Designer, was used in this research to intuitively observe the gear meshing and the load distribution conditions on the gear teeth. We obtained the optimal modification value through comparing the results of repeated experiments. For validation, optimized gears were fabricated and then measured with a precision tester.
케이블 사장교용 내고온 · 내고압 유압 펌프의 설계에 관한 연구
진진(Zhen Qin),우위팅(Yu-Ting Wu),김동선(Dong-Seon Kim),김상배(Sang-Bae Kim),류성기(Sung-Ki Lyu) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.11
Hydraulic pumps are widely used in fields such as machinery manufacturing, engineering and construction. Although the research on hydraulic engineering is mature, it is still necessary to examine various performance aspects in detail for specific applications. This paper will focus on the hydraulic pump used in special construction machinery that needs high temperature and high pressure resistance. It will analyze the theoretical design, structure and thermal characteristics of the pump system using the Fundamentals of Engineering (FE) method, and will measure the key tolerance parameters of the hydraulic pump to ensure the accuracy of the machining. Through this research, a good design method for the linear reciprocating type of hydraulic pump can be summarized.