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2 x 2 광 연결기를 이용한 광섬유의 반사 손실 측정 장치 개발
서정철,이덕희 한국물리학회 2005 새물리 Vol.50 No.6
To establish the national traceability for return loss measurements on optical bers and devices,we developed a return loss measurement system by using a 2 2 optical coupler. Our return loss measurement system, with calibrated optical sources, calibrated detectors and an optical coupler, has a good measurement uncertainty within 0.6-dB in the 60 dB dynamic ranges. The return loss of ber optic devices, such as NPL(National Physical Laboratory)'s CRM(Certied Reference Material)s was easured and compared at wavelengths of 1310-nm and 1550-nm wavelength ranges. Our results are in a good agreement with those reported by NPL.
서정철,이희영 영남대학교 공업기술연구소 2000 工業技術硏究所論文集 Vol.28 No.1
Effects of sintering temperature and time on relative permittivity εr, unloaded quality factor Q·f and temperature coefficient of resonant frequency τf of dielectric resonator materials produced from commercial ZST powder were investigated in some detail. Q·f values, as determined from cavity perturbation method at 1.6GHz, gradually increased with sintering temperature reaching the maximum at 1420℃. However, bulk density and relative permittivity values, which increased with temperature, started to decrease above 1380℃. In addition, Q·f values slightly increased wish sintering time at the sintering temperature of 1300℃∼1380℃, while bulk density and relative permittivity values were approximately constant. It was also found that τf values were not affected by sintering temperature and time within the experimental conditions used.
서정철,임강현,한상원,Seo, Jung-Chul,Leem, Kang-Hyun,Han, Sang-Won 대한약침학회 2003 Journal of pharmacopuncture Vol.6 No.1
Bee venom has been clinically used to control the pain of inflammation disease etc. in general. Although the effect of bee venom herbal acupuncture has been reported, its mechanism has not been fully elucidated yet. Free radical metabolism seems to occupy a remarkably common position in the mechanisms of inflammation and ageing related disease. Oxidative damage to DNA, lipids, proteins and other molecules may contribute to the development inflammation disease. NO or DPPH is one of the free radicals and a mediator in inflammation diseases. The objective of this study is to investigate the scavenging effect of bee venom herbal acupuncture against NO and DPPH. The followings are the summary of the results: (1) There is no significant scavenging effect of bee venom herbal acupuncture on NO in BVS and BVP group. (2) There is a significant scavenging effect of bee venom herbal acupuncture on DPPH in BVS-1 and BVP-1 group. These results suggest that bee venom herbal acupuncture can be used for inflammation diseases such as rheumatoid arthritis. This study would provide important basic data on the possibility of the clinical treatment of bee venom herbal acupuncture. Further studies are required to investigate the antioxidative effects of it.
Al₂O₃-ZrO₂/Al₂O₃-TZP 세라믹스의 기계적 특성 및 열충격 거동
서정철,박재성,남효덕 영남대학교 공업기술연구소 1999 工業技術硏究所論文集 Vol.27 No.2
The effects of the addition of either monoclinic ZrO2(pure) or tetragonal ZrO2 containing 5.35wt% Y2O3 (Y-TZP) on the mechanical properties and thermal shock resistance of Al2O3 ceramics were investigated. The addition of ZrO2(m) and Y-TZP increased sintered density of Al2O3. The Vickers hardness also increased as the volume fraction of Y-TZP increased going through a maximum at 20wt%. The hardness of the specimens was found to be dependent on the sintered density. The higher volume fraction of either ZrO2(m) or Y-TZP resulted in the higher fracture toughness of the composite was. This result may be taken as evidence that toughening of Al2O3 can be achieved by not only the transformation toughening but microcrack toughening of ZrO2. The thermal shock property for Al2O3-ZrO2 composites was improved by increasing the volume fraction of monoclinic ZrO2(pure). The grain size increased as the volume fraction of ZrO2 did.
非晶質强磁性體 Fe_40Ni_38Mo_4B_18의 磁氣場分布에 관한 연구
徐廷鐵,金允坤 圓光大學校 基礎自然科學硏究所 1984 基礎科學硏究誌 Vol.3 No.2
In amorphous state, atomic structure is disordered and the hyperfine field, quadropule splitting and isomer shift are different in each atom. According to this, Mo¨ssbauer spectrum consists many overlapping lines. In principle, we can describe such systems by the distributions of hyperfine field, quadropule splitting and isomer shift were taken at various temperatures ranging from 82˚K to 428˚K.