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RISS 인기검색어
- 검색키워드
- 저자 : Yun Sang-Pil (검색결과 630 건)
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Yun, Seung Pil,Han, Yong-Seok,Lee, Jun Hee,Kim, Sang Min,Lee, Sang Hun The Korean Society of Applied Pharmacology 2018 Biomolecules & Therapeutics(구 응용약물학회지) Vol.26 No.4
p-Cresol, found at high concentrations in the serum of chronic kidney failure patients, is known to cause cell senescence and other complications in different parts of the body. p-Cresol is thought to mediate cytotoxic effects through the induction of autophagy response. However, toxic effects of p-cresol on mesenchymal stem cells have not been elucidated. Thus, we aimed to investigate whether p-cresol induces senescence of mesenchymal stem cells, and whether melatonin can ameliorate abnormal autophagy response caused by p-cresol. We found that p-cresol concentration-dependently reduced proliferation of mesenchymal stem cells. Pretreatment with melatonin prevented pro-senescence effects of p-cresol on mesenchymal stem cells. We found that by inducing phosphorylation of Akt and activating the Akt signaling pathway, melatonin enhanced catalase activity and thereby inhibited the accumulation of reactive oxygen species induced by p-cresol in mesenchymal stem cells, ultimately preventing abnormal activation of autophagy. Furthermore, preincubation with melatonin counteracted other pro-senescence changes caused by p-cresol, such as the increase in total 5'-AMP-activated protein kinase expression and decrease in the level of phosphorylated mechanistic target of rapamycin. Ultimately, we discovered that melatonin restored the expression of senescence marker protein 30, which is normally suppressed because of the induction of the autophagy pathway in chronic kidney failure patients by p-cresol. Our findings suggest that stem cell senescence in patients with chronic kidney failure could be potentially rescued by the administration of melatonin, which grants this hormone a novel therapeutic role.
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Development of the Proton Beam Monitoring System at the 45-MeV Proton Irradiation Test Facility
Sang-Pil Yun,In-Seok Hong,Yong-Sub Cho 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.3
A proton beam monitoring system has been developed to measure the intensity and the profile of an external proton beam. The beam monitoring system, which consists of a beam intensity monitor and a beam profile monitor (BPM), can provide the intensity and the profile of a proton beam. As a beam monitor for the intensity measurement, a parallel plate ionization chamber (PPIC) is chosen because of its stable operation and wide dynamic range for the detection of a proton beam. To maintain the beam quality, the PPIC electrodes were fabricated with a very thin aluminized polyester film (25 μm). The structure of the BPM is similar to that of the PPIC, except that the BPM is equipped with a position-sensitive electrode. This position-sensitive electrode allows the BPM to measure the profile of a proton beam. The signals from the beam intensity monitor and the BPM are recorded by using a Lab-view-based PXI system (National Instruments Co.), which displays information on both the intensity and the profile by using a proton beam analysis program supported by Lab-view. As a result, we can monitor information on the proton beam during irradiation tests by using a remote control. A proton beam monitoring system has been developed to measure the intensity and the profile of an external proton beam. The beam monitoring system, which consists of a beam intensity monitor and a beam profile monitor (BPM), can provide the intensity and the profile of a proton beam. As a beam monitor for the intensity measurement, a parallel plate ionization chamber (PPIC) is chosen because of its stable operation and wide dynamic range for the detection of a proton beam. To maintain the beam quality, the PPIC electrodes were fabricated with a very thin aluminized polyester film (25 μm). The structure of the BPM is similar to that of the PPIC, except that the BPM is equipped with a position-sensitive electrode. This position-sensitive electrode allows the BPM to measure the profile of a proton beam. The signals from the beam intensity monitor and the BPM are recorded by using a Lab-view-based PXI system (National Instruments Co.), which displays information on both the intensity and the profile by using a proton beam analysis program supported by Lab-view. As a result, we can monitor information on the proton beam during irradiation tests by using a remote control.
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Weld line detection algorithm for radiography test of welding beads in a ship piping system
Sang Jun Lee,Jong Pil Yun,Gyogwon Koo,Hyeyeon Choi,Sang Woo Kim 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10
Inspection of welding beads is important to achieve reliability of welding condition. Radiography testing is a widely used method in ship piping systems to verify welding quality. In our industry problem, a mobile robot was utilized to radiate X-ray outwards from inside of a pipe. Because small amount of radiation is allowed by the legal regulation, precise localization of a weld line is required. This paper proposes a robot vision algorithm to precisely localize the position of a weld line in a piping system. The proposed algorithm detects a weld line and loosely localizes the position by using a difference of Gaussian. For a sub-region that contains the loosely localized weld line, morphological operations are applied to precisely localize the position of the weld line. Experiments were conducted on real industry data to demonstrate the effectiveness of the proposed algorithm.
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WETTABILITY AND DRUG DELIVERY OF FUNCTIONALLY GRADED NANO-MICRO POROUS TITANIUM SURFACE
Yun, Kwi-Dug,Vang, Mong-Sook,Yang, Hong-So,Park, Sang-Won,Park, Ha-Ok,Lim, Hyun-Pil The Korean Academy of Prosthodonitics 2008 대한치과보철학회지 Vol.46 No.3
STATEMENT OF PROBLEM: It is known that an anodic oxidation technique, one of the methods for the implant surface treatment, remarkably increased surface area, enhanced wettability and accelerated the initial bone healing. Purpose: This study was performed to evaluate the wettability of anodized titanium surface which has a nanotubular structure, to assess osseointegration after the placement of implant with nano-size tubes on tibia of rats and to analyze quantitatively transferable rhBMP-2 on each surface. MATERIAL AND METHOD: Four different kinds of surface-treated titanium discs (polished (machined surface) group, micro (blasting surface) group, nano (anodizedmachined surface) group, and nano-micro (anodized-blasting surface) group) were fabricated (n=10). Three different media were chosen to measure the surface contact angles; distilled water, plasma and rhBMP-2 solution. After a single drop (0.025 $m{\ell}$) of solution, the picture was taken with the image camera, and contact angle was measured by using image analysis system. For the test of osseointegration, 2 kinds of anodized surface (anodized-machined surface, anodized-blasting surface) implants having 2.0 mm in diameter and 5.0 mm in length inserted into the tibia of Wistar rats. After 3 weeks, tibia were harvested and the specimens were stained with hematoxylin and eosin for histological analysis. To test the possibility of drug delivery, after soaking sample groups in the concentration of 250 ng/$m{\ell}$l of rhBMP-2 for 48 hours, the excess solution of rhBMP-2 were removed. After that, they were lyophilized for 24 hours, and then the rhBMP-2 on the surface of titanium was resolved for 72 hours in PBS. All the extracted solution was analyzed by ELISA. One-way analysis of variance (ANOVA) was performed on the data. RESULTS: The wettability is improved by anodic oxidation. The best wettability was shown on the nano-micro group, and it was followed by nano group, micro group, and polished group. In the histological findings, all implants showed good healing and the new bone formation were observed along the implant surface. After 3 days, nano-micro group delivered the most amount of rhBMP-2, followed by nano group, micro group, and polished group. CONCLUSION: It indicated that anodic oxidation on blasting surface produce functionally graded nano-micro porous structure and enhance hydrophilicity of the surface and osseointegration. The findings suggest that the nano-micro porous structure could be a useful carrier of osteogenic molecules like rhBMP-2.
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Yun, Kwi-Dug,Yang, Yunzhi,Lim, Hyun-Pil,Oh, Gye-Jeong,Koh, Jeong-Tae,Bae, In-Ho,Kim, Jaehyung,Lee, Kwang-Min,Park, Sang-Won Elsevier 2010 Materials science & engineering. C, Materials for Vol.30 No.1
<P><B>Abstract</B></P><P>This study was to evaluate wettability, cell response, and osseointegration of nanotubular titanium (Ti) surface by anodic oxidation. Commercially pure Ti discs were treated by polishing, sandblasting, and anodizing. These surfaces were characterized by scanning electron microscopy and contact angle measurement. MC3T3-E1 osteoblast cell was used to evaluate cell response <I>in vitro</I>. The cell morphology, cell viability, and alkaline phosphatase (ALP) specific activity were assessed. The Ti implants of 2.0mm diameter and 5.0mm long treated by anodizing and sandblasting/anodizing were inserted into the tibia of rats. After 3weeks, the histology of the Ti–bone interface was examined. SEM observations showed that the anodizing and sandblasting/anodizing created the nanotubular surface and graded nanotubular-micro-roughened surfaces, respectively. The anodizing and sandblasting/anodizing significantly improved the hydrophilicity of Ti. The significant greatest cell spreading and ALP specific activity were observed on the graded nanotubular-micro-roughened surfaces treated by sandblasting/anodizing. The <I>in vivo</I> study shows that newly formed bone was intimately in contact with the nanotubular surfaces without adverse immune response. This study has suggested that the graded nanotubular-micro-roughened surface of Ti treated with sandblasting/anodizing is very promising in implantology due to improved hydrophilicity, favorable cell response, and excellent osseointegration.</P>
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Yun, Jeong Woo,Yoon, Sung Pil,Park, Sanggyun,Han, Jonghee,Nam, Suk Woo,Lim, Tae-Hoon,Kim, Jin-Soo Elsevier 2009 INTERNATIONAL JOURNAL OF HYDROGEN ENERGY - Vol.34 No.22
<P><B>Abstract</B></P><P>To increase the performance of solid oxide fuel cells operated at intermediate temperatures (<700°C), we used the electronic conductor La<SUB>0.8</SUB>Sr<SUB>0.2</SUB>MnO<SUB>3</SUB> (LSM) and the mixed conductor La<SUB>0.6</SUB>Sr<SUB>0.4</SUB>Co<SUB>0.2</SUB>Fe<SUB>0.8</SUB>O<SUB>3</SUB> (LSCF) to modify the cathode in the electrode microstructure. For both cathode materials, we employed a Sm<SUB>0.2</SUB>Ce<SUB>0.8</SUB>O<SUB>2</SUB> (SDC) buffer layer as a diffusion barrier on the yttria-stabilized zirconia (YSZ) electrolyte to prevent the interlayer formation of SrZrO<SUB>3</SUB> and La<SUB>2</SUB>Zr<SUB>2</SUB>O<SUB>7</SUB>, which have a poor ionic conductivity. These interfacial reaction products were formed only minimally at the electrolyte–cathode interlayer after sintering the SDC layer at high temperature; in addition, the degree of cathode polarization also decreased. Moreover to extend the triple phase boundary and improve cell performance at intermediate temperatures, we used sol–gel methods to coat an SDC layer on the cathode pore walls. The cathode resistance of the LSCF cathode cell featuring SDC modification reached as low as 0.11Ωcm<SUP>2</SUP> in air when measured at 700°C. The maximum power densities of the cells featuring the modified LSCF and LSM cathodes were 369 and 271mW/cm<SUP>2</SUP>, respectively, when using O<SUB>2</SUB> as the oxidant and H<SUB>2</SUB> as the fuel.</P>
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