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하이브리드 여자방식을 이용한 SRM 의 진동 소음 저감
김창섭,이상훈,안진우 경성대학교 공학기술연구소 2000 공학기술연구지 Vol.7 No.-
The simple motor construction and low cost, fault tolerant power electronic drive has made the switched reluctance drive a strong contender for many applications. But the switched reluctance drive does exhibit higher levels of vibration and acoustic noise than most competing drives. The main source of vibration in the switched reluctance drive is generated by rapid change of radial force when phase current is exthinguished by commutation action. In this paper, a hybrid excitation method is proposed to reduce vibration and acoustic noise of the switched reluctance drive. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are reduced because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.
김창섭,이상훈,안진우 경성대학교 공학기술연구소 2000 공학기술연구지 Vol.7 No.-
An SRM for a pallet truck drive is developed and tested. The drive system has to operate with low voltage and high current, and has to have the characteristics of DC series motor. The small size, ruggedness high efficiency make it possible to replace with DC motor. Test results show that pallet truck with SRM has better performance characteristics than that of the DC motor's.
진공청소기용 팬 모터의 비정상 유동 해석 및 공력소음 해석
김재열,심재기,송경석,오성민,양동조,김우진 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-
The vacuum cleaner motor runs on very high speed for the suction power. Specially, the motive power is provided by the impeller being rotate on very high speed. And centrifugal fan consists of the impeller, the diffuser, and the circular casing. Due to the high rotating speed of the impeller and small gap distance between the impeller and diffuser, the centrifugal fan makes very high noise level at BPF and harmonic frequencies. In order to calculate the sound pressure of centrifugal fan, the unsteady flow data is needed. And Noise cause is dividing to fluid noise by exhaust flow of fan and vibration noise by rotational vibration of vacuum cleaner fan motor. Until now, measuring method has been used to measure vibration by the accelerometer; this method has been not measured for the vibration in some parts of brush and commutator because of motor construction and 3-D vibrating mode. This paper was purposed on the accurate analysis, using laser vibration analyzer, By using this measured data of noise cause against the difficult part in old times, we would like to use for the design of silent fan motor.
酸棗仁이 CT105에 의한 신경세포 상해 및 白鼠의 기억에 미치는 영향
정정욱,박창국,박치상,이소연,윤현덕,신오철 대한본초학회 2005 大韓本草學會誌 Vol.20 No.1
Objective: This study was designed to research whether demonstrate neuroprotective and memory enhancing effects of Z1BU, suggesting its beneficial actions for the treatment of AD. Methods: The present study investigated effects of the dichloromethane extract of Semen Zizyphi Spinosae(ZIBU) on neurotoxicity and reactive oxygen species(ROS) and nitric oxide(NO) formation in PC 12 cell line overexpressed with carboxyl-terminal 105 amino acid peptide fragment of amyloid precursor protein(CT105). In addition, the present study evaluated its radical scavenging activity and effects on acetylcholinesterase(AChE) activity. Furthermore, effects on neuronal loss in CAl area and cognitive deficits induced by scopolamine treatment were also evaluated in rats. Result: we found in this study that ZIBU significantly inhibited apoptotic neuronal death induced by CT105 overexpression in PC12 cells, with the IC_(50) value of 23 ㎍/ml. Based on phase-contrast and fluorescence microscopic examinations, ZIBU reversed morphological changes of CT105-expressed PC-12 cells. It was also found that Z1BU significantly induced neurite outgrowth and inhibited formation of ROS and NO.Z1BU scavenged DPPH radicals and inhibited AChE activity. Furthermore, it attenuated memory impairment induced by the injection of scopolamine in rats, based on passive avoidance test. Crystal violet staining of rat brain slices exhibited increase in the viability of pyramidal neurons in hippocampal CAI area. Conclusion: these results demonstrate neuroprotective and memory enhancing effects of ZIBU, suggesting its beneficial actions for the treatment of AD.
Han, Sang A.,Lee, Kang Hyuck,Kim, Tae-Ho,Seung, Wanchul,Lee, Seok Kyeong,Choi, Sungho,Kumar, Brijesh,Bhatia, Ravi,Shin, Hyeon-Jin,Lee, Woo-Jin,Kim, SeongMin,Kim, Hyoung Sub,Choi, Jae-Yong,Kim, Sang-Wo Elsevier 2015 Nano energy Vol.12 No.-
<P><B>Abstract</B></P> <P>Here we demonstrate the deposition of a high-k dielectric material on graphene using hexagonal boron nitride (h-BN) nanosheets as a buffer layer. The presence of an h-BN layer on top of the graphene facilitated the growth of high-quality Al<SUB>2</SUB>O<SUB>3</SUB> by atomic layer deposition (ALD). Simulation results also support the experimental observations and provide an explanation for the suitability of h-BN as a buffer layer in terms of mixed ionic-covalent B–N bonding. Additionally, h-BN works as a protective shield to prevent graphene oxidation during ALD of Al<SUB>2</SUB>O<SUB>3</SUB> for the fabrication of graphene-based devices. Finally, triboelectric nanogenerators (TNGs) based on both Al<SUB>2</SUB>O<SUB>3</SUB>/h-BN/graphene and Al<SUB>2</SUB>O<SUB>3</SUB>/graphene structures are demonstrated for further confirming the importance of h-BN for synthesizing high-quality Al<SUB>2</SUB>O<SUB>3</SUB> on graphene. It was found that the Al<SUB>2</SUB>O<SUB>3</SUB>/h-BN/graphene-based TNG reveals meaningful electric power generation under a mechanical friction, while no significant electric power output from the Al<SUB>2</SUB>O<SUB>3</SUB>/graphene-based TNG is obtained, indicating high charge storage capacity of the dielectric Al<SUB>2</SUB>O<SUB>3</SUB> layer on h-BN.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A easy method for the formation of stoichiometric Al<SUB>2</SUB>O<SUB>3</SUB> on CVD-grown h-BN/graphene. </LI> <LI> The presence of an h-BN layer facilitates the growth of high-quality Al<SUB>2</SUB>O<SUB>3</SUB> by ALD. </LI> <LI> h-BN works as a protective layer to prevent graphene oxidation during ALD process. </LI> <LI> Flexible transparent triboelectric nanogenerators based on Al<SUB>2</SUB>O<SUB>3</SUB>/h-BN/graphene. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>