Carbide Ceramics from Active-Filler-Controlled Pyrolysis in Atmosphere

Kang Keon-Taek,Kim Deug-Joong,Annette Kain이,Peter Greil 한국분말야금학회 1999 한국분말야금학회지 Vol.6 No.4

The formation, microstructure and properties of novel ceramic composite materials manufactured by active-filler-controlled polymer pyrolysis were investigated. In the presence of active filler particles such as transition metals, bulk components of various geometry could be fabricated from siliconorganic polymer. Molybdenum- and tungsten-filled polymer suspensions were prepared and their conversion to ceramic composites by annealing in atmosphere were studied. Dimensional change. porosity and phase distribution (filler network) were analyzed and correlated to the resulting hardness values. Molybdenum and tungsten as active filler were carburized completely to , and WC in atmosphere. Consequently, microcrystalline composites with the filler reaction products embedded in a silicon oxycarbide glass matrix were formed. Hardness was increased with increasing carburization and reached 8.6-9.5 GPa in the specimen pyrolyzed in atmosphere.

Improving differential mode inductance in toroidal common mode inductors

Kaining Fu,Zhenzhu Lian,Wei Lan,Damin Zhang 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.12

Toroidal inductors are widely used in switch mode power supplies to attenuate electromagnetic interference (EMI). However, conventional common mode (CM) inductors have limitations in achieving diff erential mode (DM) noise attenuation and may introduce near-field coupling. In this paper, the advantage and disadvantage of conventional CM inductors are investigated. An integrated inductor scheme is proposed to overcome the limitation. The proposed scheme maintains the same CM inductance as conventional toroidal CM inductors while significantly increasing the DM inductance and reducing leakage flux. This leads to reduced weight and size of discrete DM inductors and enables higher power density of the converter. The theoretical analysis is conducted using the equivalent magnetic reluctance model. Further validation is performed through 3D finite element method simulations, insertion loss measurements, and CM and DM noise spectrum measurements. Results demonstrate that the proposed integrated inductor scheme offers superior EMI performance compared with conventional CM inductors.

A giant planet beyond the snow line in microlensing event OGLE-2011-BLG-0251

Kains, N.,Street, R. A.,Choi, J.-Y.,Han, C.,Udalski, A.,Almeida, L. A.,Jablonski, F.,Tristram, P. J.,Jørgensen, U. G.,Szymań,ski, M. K.,Kubiak, M.,Pietrzyń,ski, G.,Soszyń,ski, I.,Polesk EDP Sciences 2013 Astronomy and astrophysics Vol.552 No.-

<i>Colpomenia bullosa</i> crust masquerading as <i>Ralfsia verrucosa</i> (Phaeophyceae) in southeast Australia

Kain (Jones), Joanna M.,Buchanan, Joseph,Boo, Sung Min,Lee, Kyung Min Informa UK (TaylorFrancis) 2010 Phycologia Vol.49 No.6

A census of variability in globular cluster M 68 (NGC 4590)

Kains, N.,Arellano Ferro, A.,Figuera Jaimes, R.,Bramich, D. M.,Skottfelt, J.,Jørgensen, U. G.,Tsapras, Y.,Street, R. A.,Browne, P.,Dominik, M.,Horne, K.,Hundertmark, M.,Ipatov, S.,Snodgrass, C.,Steele EDP Sciences 2015 Astronomy and astrophysics Vol.578 No.-

<P>Aims. We analyse 20 nights of CCD observations in the V and I bands of the globular cluster M?68 (NGC 4590) and use them to detect variable objects. We also obtained electron-multiplying CCD (EMCCD) observations for this cluster in order to explore its core with unprecedented spatial resolution from the ground. Methods. We reduced our data using difference image analysis to achieve the best possible photometry in the crowded field of the cluster. In doing so, we show that when dealing with identical networked telescopes, a reference image from any telescope may be used to reduce data from any other telescope, which facilitates the analysis significantly. We then used our light curves to estimate the properties of the RR Lyrae (RRL) stars in M?68 through Fourier decomposition and empirical relations. The variable star properties then allowed us to derive the cluster’s metallicity and distance. Results. M?68 had 45 previously confirmed variables, including 42 RRL and 2 SX Phoenicis (SX Phe) stars. In this paper we determine new periods and search for new variables, especially in the core of the cluster where our method performs particularly well. We detect 4 additional SX Phe stars and confirm the variability of another star, bringing the total number of confirmed variable stars in this cluster to 50. We also used archival data stretching back to 1951 to derive period changes for some of the single-mode RRL stars, and analyse the significant number of double-mode RRL stars in M?68. Furthermore, we find evidence for double-mode pulsation in one of the SX Phe stars in this cluster. Using the different classes of variables, we derived values for the metallicity of the cluster of [Fe/H] = −2.07 ±0.06 on the ZW scale, or −2.20 ±0.10 on the UVES scale, and found true distance moduli μ0 = 15.00±0.11 mag (using RR0 stars), 15.00 ± 0.05 mag (using RR1 stars), 14.97 ±0.11 mag (using SX Phe stars), and 15.00±0.07 mag (using the MV–[Fe/H] relation for RRL stars), corresponding to physical distances of 10.00 ±0.49, 9.99±0.21, 9.84 ±0.50, and 10.00 ±0.30 kpc, respectively. Thanks to the first use of difference image analysis on time-series observations of M?68, we are now confident that we have a complete census of the RRL stars in this cluster.</P>

Balance Winding Scheme to Reduce Common-Mode Noise in Flyback Transformers

Kaining Fu,Wei Chen 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1

The flyback topology is being widely used in power adapters. The coupling capacitance between primary and secondarywindings of a flyback transformer is the main path for common-mode (CM) noise conduction. A Y-cap is usually used toeffectively suppress EMI noise. However, this results in problems in space, cost, and the danger of safety leakage current. In thispaper, the CM noise behaviors due to the electric field coupling of the transformer windings in a flyback adapter withsynchronous rectification are analyzed. Then a scheme with balance winding is proposed to reduce the CM noise with atransformer winding design that eliminates the Y-cap. The planar transformer has advantages in terms of its low profile, goodheat dissipation and good stray parameter consistency. Based on the proposed scheme, with the help of a full-wave simulationtool, the key parameter influences of the transformer PCB winding design on CM noise are further analyzed. Finally, a PCBtransformer for an 18W adapter is designed and tested to verify the effectiveness of the balance winding scheme.

High side flyback circuit configuration for CM noise cancellation

Fu, Kaining,Chen, Wei The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.5

Flyback topologies have advantages in terms of low cost, fewer electrical components, and simple circuit design. Semiconductor devices in the primary and secondary sides are regarded as major EMI noise sources in EMI propagation paths. However, the same transformers under different circuit configurations can bring different noise cancellation effects due to a change of the electric potential distribution in transformer windings as well as the phases of the EMI noise sources in the primary and secondary sides. In this paper, a CM noise cancellation mechanism is investigated. In addition, a flyback topology with high side gate driving in the primary side is proposed to form a CM noise cancellation mechanism. Based on the proposed flyback topology, the capacitor compensation cancellation technique can be applied to lower the electromagnetic interference (EMI) noise level of the designed converter. Finally, the experimental noise spectrums are used to verify the effectiveness of the proposed flyback circuit configuration scheme.

Balance Winding Scheme to Reduce Common-Mode Noise in Flyback Transformers

Fu, Kaining,Chen, Wei The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.1

The flyback topology is being widely used in power adapters. The coupling capacitance between primary and secondary windings of a flyback transformer is the main path for common-mode (CM) noise conduction. A Y-cap is usually used to effectively suppress EMI noise. However, this results in problems in space, cost, and the danger of safety leakage current. In this paper, the CM noise behaviors due to the electric field coupling of the transformer windings in a flyback adapter with synchronous rectification are analyzed. Then a scheme with balance winding is proposed to reduce the CM noise with a transformer winding design that eliminates the Y-cap. The planar transformer has advantages in terms of its low profile, good heat dissipation and good stray parameter consistency. Based on the proposed scheme, with the help of a full-wave simulation tool, the key parameter influences of the transformer PCB winding design on CM noise are further analyzed. Finally, a PCB transformer for an 18W adapter is designed and tested to verify the effectiveness of the balance winding scheme.

Effect of Cyclic Deep Cryogenic Treatment on Corrosion Resistance of 7075 Alloy

Ruiming Su,Siyi Ma,Kaining Wang,Guanglong Li,Yingdong Qu,Rongde Li 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4

The cyclic deep cryogenic treatment was proposed to improve both the hardness and corrosion resistance of the high strength7075 aluminum alloy. The effect of different CDCT times on the exfoliation corrosion and intergranular corrosion of the alloyswere observed by scanning electron microscope. The corrosion behaviors of the alloys were monitored by electrochemicaltechniques. The hardness of the alloy was measured by Vickers hardness tester. Furthermore, the microstructures of thealloys were examined by transmission electron microscope. The results show that the corrosion resistance and hardness arestrongly affected by the precipitate state. The discontinuous grain boundary precipitates and the wide precipitate free zoneswill enhance the corrosion resistance. The fine precipitates distributed evenly in the matrix can increase the hardness. Afterthe CDCT, the corrosion resistance is remarkably improved without sacrificing the hardness. The best combination of thehardness and corrosion resistance is exhibited for the alloy treated with the CDCT twice.

Application of Functional Near-Infrared Spectroscopy to the Study of Brain Function in Humans and Animal Models

Kim, Hak Yeong,Seo, Kain,Jeon, Hong Jin,Lee, Unjoo,Lee, Hyosang Korean Society for Molecular and Cellular Biology 2017 Molecules and cells Vol.40 No.8

Functional near-infrared spectroscopy (fNIRS) is a noninvasive optical imaging technique that indirectly assesses neuronal activity by measuring changes in oxygenated and deoxygenated hemoglobin in tissues using near-infrared light. fNIRS has been used not only to investigate cortical activity in healthy human subjects and animals but also to reveal abnormalities in brain function in patients suffering from neurological and psychiatric disorders and in animals that exhibit disease conditions. Because of its safety, quietness, resistance to motion artifacts, and portability, fNIRS has become a tool to complement conventional imaging techniques in measuring hemodynamic responses while a subject performs diverse cognitive and behavioral tasks in test settings that are more ecologically relevant and involve social interaction. In this review, we introduce the basic principles of fNIRS and discuss the application of this technique in human and animal studies.