Influence of Initial Pearlite Morphology on the Microstructure Evolution During Heat Treatment of 1.0C–1.5Cr Steel

Zhen‑Xing Li,Chang‑Sheng Li,Seong‑Hoon Kim,Dong‑Woo Suh 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.1

Effect of initial pearlite morphology on the microstructure evolution during spheroidization annealing and subsequent hardeningtreatment was studied in hot-rolled 1.0C–1.5Cr bearing steel. The ferrite-to-austenite transformation in spheroidizationannealing can be accelerated by refining the pearlite interlamellar spacing and pearlite colony size. Decreasing interlamellarspacing is also beneficial to increasing the number density of undissolved cementite, leading to the refining of final spheroidizedcementite. During the re-austenitizing process of hardening treatment, the smaller initial spheroidized cementiteleads to faster cementite dissolution and finer undissolved cementite particles. The prior austenite grain size after hardeningtreatment can also be decreased by refining the initial pearlite microstructure.

4-레벨 인버터를 이용한 고속 SRM 구동시스템

이동희,이진국,안진우 경성대학교 공학기술연구소 2005 공학기술연구지 Vol.12 No.-

This paper proposes high speed SRM drive system for blower with a novel 4-level inverter and precise excitation position generator. In order to get a fast build-up and a demagnetization of excitation current, 4-level inverter system is proposed. The proposed 4-level inverter has additional charge capacitor, power switch and diode in the conventional asymmetric converter. The charged high voltage is supplied to the phase winding for fast current build- up, and demagnetization current is charged to additional capacitor of 4-level inverter. In addition, a precise excitation position generator can reduce turn-on and turn-off angle error according to sampling period of digital control system. The proposed high speed SRM drive system is verified by computer simulations and experimental results.

호이스트용 SRM의 구동시스템의 특성해석

이진국,이동희,안진우 경성대학교 공학기술연구소 2005 공학기술연구지 Vol.12 No.-

This paper presents a development of Switched Reluctance Motor (SRM) drive system for a hoist application. In the hoist system, smoothing start-up and braking are very important for a protection of goods. In order to improved a start-up and a stop performance of hoist system, the smoothing operation sequence of SRM using direct instantaneous torque control is proposed. The proposed Direct Instantaneous Torque Control (DITC) the instantaneous torque of SRM according to the switching sequence and hysteric band. In order to compare the reference and actual torque of SRM, pre-measured flux and torque look-up table are regulate used. The proposed SRM Drive system is verified by the simulation result.

SRG 전력제어시스템의 효율특성 분석

Zhen-Guo Li,Dong-Dong Gao,안진우 대한전기학회 2012 대한전기학회 학술대회 논문집 Vol.2012 No.7

Influence of Kluyveromyces marxianus on proteins, peptides, and amino acids in Lactobacillus-fermented milk

Dong-Dong Zhang,Jing-Lan Liu,Tie-Min Jiang,Lu Li,Guo-Zhen Fang,Yan-Pin Liu,Li-Jun Chen 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.3

With increasing application of yeast in fermented milk, in order to study the effect of yeast on milk protein during the fermentation process, the effects of the presence of Kluyveromyces marxianus in milk fermented by Streptococcus thermophilus and Lactobacillus bulgaricus were investigated. After fermentation, the amino acid, protein, and peptide contents were analyzed by ultra-performance liquid chromatography, two-dimensional gel electrophoresis, and liquid chromatography–mass spectrometry, respectively. After the addition of K. marxianus for fermentation, 25 protein spots changed significantly. These were mostly caseins and bovine serum proteins, and the content of total free amino acids increased by 16.30%; ten types of bioactive peptides were identified. Furthermore, the number of peptide types in milk fermented by K. marxianus increased significantly compared with milk fermented by Lactobacillus. K. marxianus is considered to promote proteometabolism in milk when added with Lactobacillus, generate flavor compounds, and improve the digestion and absorption character of milk.

Proteome alterations of reverse photoperiod-sensitive genic male sterile rice (Oryza sativa L.) at fertility transformation stage

Zhen Chen,Han-lai Zeng,Haixia Li,Xueli Ma,Hongxia Dong,Dong Ma 한국유전학회 2014 Genes & Genomics Vol.36 No.6

The two-line system has been widely used inhybrid rice seed production, and the reverse photoperiodsensitivegenic male sterile line is a new germplasm withan opposite phenotype compared with normal photoperiodsensitivegenic male sterile rice. To better understand themolecular mechanisms of fertility regulation in reversephotoperiod-sensitive genic male sterile rice, a comparativeproteomic approach was used to analyze the proteinprofiles of three different tissues (young panicles, flagleaves and leaf sheaths) of D52S during the sensitive periodof pollen fertility transformation under sterile and fertileconditions. By quantitative analysis, 66 protein spotswere identified to be significantly changed in the threetissues. Bioinformatics analyses revealed that in sterilerice, a number of proteins involved in lignin-flavonoidbiosynthesis pathway were down-accumulated in panicles. The majority of proteins associated with energy metabolismwere down-accumulated in leaf sheaths while theproteins up-accumulated in leaves and leaf sheaths wereexclusively photosynthesis and defense related. Based onthe proteomics data, a short-day induced male sterilityprotein network was proposed. In addition, the genes ofselected protein spots were further analyzed by qPCR. These findings provide data for better understanding theregulation of pollen fertility in reverse photoperiodsensitivegenic male sterile rice, which could assist in thedevelopment of practical reverse photoperiod-sensitivegenic male sterile rice for large-scale crop breedingprograms.

Electrorheological response of microporous covalent triazine-based polymeric particles

Dong, Yu Zhen,Kwon, Seung Hyuk,Choi, Hyoung Jin,Puthiaraj, Pillaiyar,Ahn, Wha-Seung Springer-Verlag 2018 Colloid and Polymer Science Vol.296 No.5

Synthesis of Organic–Inorganic Poly(diphenylamine)/Magnetite Composite Particles and Their Magnetorheological Response

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>

Paradigm Reshaping of Maritime Sociology

Dong Zhen,Cui Yinji,Guo Yue 동북아시아문화학회 2018 동북아시아문화학회 국제학술대회 발표자료집 Vol.2018 No.10

Since 2004, Maritime Sociology turned to be a new researching sphere of Sociology in China. It was defined as a kind of Sociology focuses on interactive activity between Ocean and Human Being, but the fundamental researching paradigm of Maritime Sociology still lacks to clear clarification. This paper takes a theoretic path of Marx-Bourdieu to build a Maritime Practice Paradigm for Maritime Sociology, which takes human`s maritime activity as practice embedded in the environment of Field, Habitus and Capital. We thus concern that Maritime Sociology`s researching paradigm should not only follow the basic logic of social science, seeking for a causal relationship of y=f(x) to simply take the factor of Ocean as an independent (x) or dependent (y) towards Human`s practice, but also treat the factor of Ocean among the situation of practice, taking a Zigzag way to notice the different ways that Ocean and Human himself suffers changes and transformation during the process of practice. This would give Maritime Sociology something special to further and enrich our research.

Effect of CoFe₂O₄ nanoparticles on a carbonyl iron based magnetorheological suspension

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>