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백금 히터가 내장된 평면형 Bi - Sb 다중접합 열전변환기의 특성
이현철,김진섭,함성호,이종현,이정희,박세일,권성원 ( H . C . Lee,J . S . Kim,S . H . Ham,J . H . Lee,J . H . Lee,S . I . Park,S . W . Kwon ) 한국센서학회 1998 센서학회지 Vol.7 No.3
A planar Bi-Sb multijunction thermal converter with high thermal sensitivity and small ac-do transfer error has been fabricated by preparing the bifilar thin film Pt-heater and the hot junctions of thin film Bi-Sb thermopile on the Si₃N₄/SiO₂/Si₃N₄-diaphragm, which functions as a thermal isolation layer, and the cold junctions on the dielectric membrane supported with the Si-substrate, which acts as a heat sink, and its ac-do transfer characteristics were investigated with the fast reversed de method. The respective thermal sensitivities of the converter with single bifilar heater were about 10.1 mV/mW and 19.8 mV/mW in the air and vacuum, and those of the converter with dual bifilar heater were about 5.1 mV/mW and 7.fi mV/mW, and about 5.3 mV/mW and 7.8 mV/mW in the air and vacuum for the inputs of inside and outside heaters, indicating that the thermal sensitivities in the vacuum, where there is rarely thermal loss caused by gas, are higher than those in the air. The ac-do voltage and current transfer difference ranges of the converter with single bifilar heater were about ±1.80 ppm and ±0.58 ppm, and those of the converter with dual bifilar heater were about ±0.63 ppm and ±0.25 ppm, and about ±0.53 ppm and ±0.27 ppm, respectively, for the inputs of inside and outside heaters, in the frequency range below 10 kHz and in the air.
이현철,석광원,전철완,이진,이영석,김성환,Lee, H. C.,Seok, K. W.,Jon, C. W.,Lee, J.,Lee, Y. S.,Kim, S. H. 대한의용생체공학회 1996 의공학회지 Vol.17 No.3
The patency of small size vascular grafts is poor, and the blood flow characteristics in the artery graft anastomosis are suspected as one of the important factors influencing intimal hyperplasia. Disturbed flow patterns caused by sixte and compliance mismatch generate unfavorable flow environment which promotes intimal thickening. Tapered vascular yuts are suggested in order to reduce sudden expansion near the anastomosis. The photochromic flow visualization method is used to measure the flout fields in the end-to-end anastomosis model under the carotid and femoral artery flow wave form. The results show that flow disturbance near the anastomosis is diminished in the tapered grafts comparing to the tubular graft. As the divergent ang1e decreases, we can reduce the low and oscillatory wall shear stress zone which is prone to intimal hyperplasia. The flow wave form effects the wall shear rate dis- tribution significantly. The steep deceleration and back flow in the femoral flow wAve form cause low mean wall shear rate and high oscillatory shear index.
말단비대증 환자의 뇌하수체 종양조직에서 H - ras 유전자 변이의 가능성
임승길(S . K . Lim),권이현(Y . H . Kwon),정윤석(Y . S . Chung),안광진(K . J . Ahn),이은직(E . J . Lee),김경래(K . R . Kim),이현철(H . C . Lee),허갑범(K . B . Huh),김태승(T . S . Kim) 대한내과학회 1993 대한내과학회지 Vol.45 No.3
Backround: Little is known about the mechanism of tumorigenesis in pituitary adenomas. An important finding in somatotroph adenomas is that a somatic mutation may convert a G protein, Gs(α) into a putative oncogene termed gsp via point mutations at two critcal sites. The ras protooncogenes are structurally related to the G-protein family and are involved in cell proliferation and differentiation. Although ras oncogene mutations have been indentified in a wide variety of human neoplasm, only one case was reported as containting single point mutation in a patient with invasive prolactinoma, In this report we used oligonucleotide-specific hybridization to screen ras mutations in 13 acromegalic tumors. Methods: Pituitary tissue samples were derived from a central portion of the paraffin embedded pituitary tumor to minimize the possibility of contamination with normal tissue. Genomic DNA was isolated and purified from tumor tissue and amplified by the standard PCR method. Amplified DNAs from each of the region of H-ras genes (12/13 and 61) were analyzed for potential ras mutations using oligonucleotide-specific hybridization as described previously. Results: Wild type radiolabelled oligoncleotides were hybridized to the amplified DNAs from the patients' tumor and to the positive specimens. They were, however, easily striped out at 68℃ by nonstringent washing procedures except control (wild type) specimens. All radiolabelled mutant oligonucleotides could be easily striped out of 13 specimens except a control mutant specimen by the same procedure. Conclusion: We could not find any H-ras mutation that might not be frequently found in acromegalic patients, and that gsp (Gsa mutation) or mutations in the PKA system-related proteins might be the main oncogene in acromegalic patients. However further efforts to find the other somatic mutations including K-ras and N-ras should be given to these patients for more precise understanding of pathogenesis and for planning of the better treatment.