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단상유도전동기의 최적 구동을 위한 디지털 위상각 제어기 설계
박수강,백형래,김평호 조선대학교 에너지.자원신기술연구소 1999 에너지·자원신기술연구소 논문지 Vol.21 No.2
The availability of microcontrollers and switching power devices such as power MOSFET, IGBT, TRIAC, ect., offer improvement opportunities in the field of ac drive system control. In this paper, a microprocessor-based controller for self-starting and power saving single phase induction motor driven system from a variable phase angle power supply is described. The controller is capable of operating in the maximum efficiency region as well as in the optimal input power region. The implementation of the software is based on an PIC16C71 8-bit programmable microcontroller that has the potential of computing the switching instants on line an in real-time. The variable phase angle switching strategy more employed for self-starting and phase angle control of the motor than the PWM switching strategy. The performance of the developed system is evaluated using computer simulation on a 210W capacitor starting motor. Finally the validity and performance capability of the controller are experimentally demonstrated on a 210W single phase induction motor.
Kim, Su-Hwan,Kim, Kyoung-Hwa,Seo, Byoung-Moo,Koo, Ki-Tae,Kim, Tae-Il,Seol, Yang-Jo,Ku, Young,Rhyu, In-Chul,Chung, Chong-Pyoung,Lee, Yong-Moo Wiley (John WileySons) 2009 Journal of periodontology Vol.80 No.11
<P>BACKGROUND: The present study was undertaken to evaluate the potential of periodontal ligament stem cells (PDLSCs) and bone marrow SCs (BMSCs) on alveolar bone regeneration in a canine peri-implant defect model. METHODS: Four adult, male beagle dogs were used in this study. Autologous BMSCs from the iliac crests and PDLSCs from extracted teeth were cultured. Three months after extraction, BMSC- and PDLSC-loaded hydroxyapatite/beta-tricalcium phosphate (HA/TCP) (test groups) and cell-free HA/TCP (control group) were implanted in three rectangular, saddle-like peri-implant defects, respectively. The left side of the mandible was initially prepared, and after 8 weeks, the right side was also prepared. The animals were sacrificed after an 8-week healing period. Undecalcified ground sections were prepared. New bone formation and bone-to-implant contact (BIC) were measured histomorphometrically. BMSCs and PDLSCs were fluorescently labeled and traced. RESULTS: Alveolar bone regeneration in surgically created peri-implant saddle-like defects was more effective in test groups than the control group. The BMSC group had the highest new bone formation (34.99% and 40.17% at healing times of 8 and 16 weeks, respectively) followed by the PDLSC group (31.90% and 36.51%) and control group (23.13% and 28.36%), respectively. Test groups exhibited a significantly higher new bone formation than the control group at 8 weeks, but the same was true for only the BMSC group at 16 weeks (P <0.05). Fluorescently labeled cells were identified adjacent to HA/TCP carriers and, partly, near connective tissues and osteoids. CONCLUSION: This study demonstrated the feasibility of using stem cell-mediated bone regeneration to treat peri-implant defects.</P>
Kim, Jong-Min,Kim, Yoonyoung,Shim, Jae-Hyeok,Lee, Young-Su,Suh, Jin-Yoo,Ahn, Jae-Pyoung,Kim, Gyeung-Ho,Cho, Young Whan Cambridge University Press 2013 Microscopy and microanalysis Vol.19 No.5
<B>Abstract</B><P>The microstructural analysis of the dehydrogenation products of the Ca(BH4)2-MgH2 composite was performed using transmission electron microscopy. It was found that nanocrystalline CaB6 crystallites formed as a dehydrogenation product throughout the areas where the signals of Ca and Mg were simultaneously detected, in addition to relatively coarse Mg crystallites. The uniform distribution of the nanocrystalline CaB6 crystallites appears to play a key role in the rehydrogenation of the dehydrogenation products, which implies that microstructure is a crucial factor determining the reversibility of reactive hydride composites.</P>
Kim, Hak-Sung,Kim, Kyoung-Hwa,Kim, Su-Hwan,Kim, Young-Sung,Koo, Ki-Tae,Kim, Tae-Il,Seol, Yang-Jo,Ku, Young,Rhyu, In-Chul,Chung, Chong-Pyoung,Lee, Yong-Moo Korean Academy of Periodontology 2010 Journal of Periodontal & Implant Science Vol.40 No.6
Purpose: The aim of this study was to investigate the immunomodulatory effects of canine periodontal ligament stem cells on allogenic and xenogenic immune cells in vitro. Methods: Mixed cell cultures consisting of canine stem cells (periodontal ligament stem cells and bone marrow stem cells) and allogenic canine/xenogenic human peripheral blood mononuclear cells (PBMCs) were established following the addition of phytohemagglutinin. The proliferation of PBMCs was evaluated using the MTS assay. The cell division of PBMCs was analyzed using the CFSE assay. The apoptosis of PBMCs was assessed using the trypan blue uptake method. Results: Periodontal ligament stem cells and bone marrow stem cells inhibited the proliferation of allogenic and xenogenic PBMCs. Both periodontal ligament stem cells and bone marrow stem cells suppressed the cell division of PBMCs despite the existence of a mitogen. No significant differences in the percentages of apoptotic PBMCs were found among the groups. Conclusions: Canine periodontal ligament stem cells have an immunomodulatory effect on allogenic and xenogenic PBMCs. This effect is not a product of apoptosis of PBMCs but is caused by the inhibition of cell division of PBMCs.