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초정밀가공기를 이용한 Zerodur의 연삭 특성에 관한 연구
김주환,김건희,한정열,김석환,원종호 한국공작기계학회 2003 한국공작기계학회 춘계학술대회논문집 Vol.2003 No.-
We explored a new rough grinding technique on optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of diamond resin bond wheel. The grinding parameters such as workpiece rotation speed, depth of cut and feed rate were altered while grinding the workpiece surfaces of 20mm in diameter. Surface roughness is measured by Form Talysurf series2. Our target is to define grinding conditions producing the surface roughness better than 0.02μm Ra and the form accuracy of around 0.2μm PV.
Kim, Sug-Whan,Chun, Mun-Suk The Korean Astronomical Society 1984 Journal of The Korean Astronomical Society Vol.17 No.1
From the PDS scanning, isophote maps and surface luminosity distributions for the late type spiral galaxy NGC 6946 were obtained. Surface luminosity distribution showed that this galaxy can be classified as the Freeman's type II, and the deep spheroidal component was caused as a result of the ring structure in the central part of NGC 6946. Physical parameters-total magnitude ($M_T^B$), effective radius ($R_e^*$), central surface magnitude $U(0)_{CD}$, length scale (${\alpha}^{-1}$), disk-to-bulge ratio (D/B) and mass-to-luminosity ratio (M/L)-were also calculated, and the results show that NGC 6946 belongs to Sc I type galaxy according to the DDO classification, and is to be a fair sample of classification statge T=6.
Mutational Analysis of the Tumor Suppressor WTX Gene in Non-small Cell Lung Cancer
Moon, Seok Whan,Chung, Yeun Jun,Yoo, Nam Jin,Kim, Min Sung,Lee, Sug Hyung 대한폐암연구회 2008 Journal of Lung Cancer Vol.7 No.1
Purpose: In a recent study of Wilms' tumors, a new X chromosome gene, Wilms' tumor gene on the X chromosome (WTX), was discovered that was found to harbor small deletions and point mutations. The WTX protein negatively regulates Wnt/β-catenin signaling, and is considered to be a tumor suppressor gene. One of the questions about the WTX gene is whether the genetic alterations of the WTX gene are specific only to Wilms' tumors. The aim of this study was to explore whether the WTX gene mutation is a characteristic of human non-small cell lung cancer (NSCLC). Materials and Methods: In the current study, we analyzed the part of the WTX gene encoding the N-terminal of WTX, where most of the WTX point mutations have been detected in Wilms' tumors. Forty-eight NSCLC tissues were analyzed by a single-strand conformation polymorphism assay and DNA sequencing. Results: SSCP analysis revealed no evidence of somatic mutations in the DNA sequences encoding the N-terminal of the WTX gene in the 48 NSCLC tissues. Conclusion: The data presented here indicate that the WTX gene may not be somatically-mutated in human NSCLCs, and suggest that NSCLCs may not utilize mutational events of the WTX gene in the process of pathogenesis.
이중양분선택법에 의한 한강 수변 경관의 가치 추정과 그 시사점 -지수지불의사 모형을 중심으로-
한택환 ( Taek Whan Han ),홍이석 ( Yi Seok Hong ),박창석 ( Chang Sug Park ) 한국환경경제학회·한국자원경제학회(구 한국환경경제학회) 2013 자원·환경경제연구 Vol.22 No.1
본 연구는 한강 수계의 수변경관 및 생태계의 보전 가치를 이중양분선택법에 의한 조건부 가치평가법 (Contingent Valuation Method, CVM)을 사용하여 추정하였다. 음이 아닌 지불의 사를 구하기 위해 지수지불의사 모형을 사용하였는데 이 모형이 특히 이중양분선택법에서 매우 중요한 것으로 분석되었다. 한강수계권역의 경관 및 생태계 보전에 대한 총 지불의사는 연간 약 7,055억원으로 추정되었다. 이는 한강 등 수계권역의 수변경관 및 생태계 보전을 위하여 필요한 예산규모가 더욱 확대될 필요성이 있음을 시사한다고 해석된다. This paper estimated the value of waterside landscape and ecosystem of Han River basin with a double-bound dichotomous choice type of CVM. We used the exponential willingness to pay model to represent the nonnegative willingness to pay. This model is found to be especially important in analyzing a double-bound dichotomous choice model. The total willingness to pay was estimated as 705.5 billion won per annum. This suggests that current budget size for water quality and ecosystem conservation for Han River needs to be expanded.
생체합금 Titanium의 표면처리에 따른 골반응의 변화에 대한 조직학적 관찰
안면환,이동철,최용석,장재혁,안종철,서재성 영남대학교 의과대학 1996 Yeungnam University Journal of Medicine Vol.13 No.1
생체합금의 생체적합성을 검증하기 위해, 표면처리가 되지 않는 타이타늄봉과 표면처리를 시행한 타이타늄 봉을 실험용토끼의 대퇴골 근위부에 삽입하여 6주, 12주, 및 26주후 방사선 관찰 후 광학현미경석 검사를 통한 골 반응을 비교관찰하였다. 전 례에서 부식에 의한 반응은 관찰되지 않았으며, 신생골의 증식은 타이타늄의 삽입 후 26주까지 경도의 골증식이 관찰되었으나, 표면처리여부에는 관계가 없었다. 표면처리를 시행하지 않은 타이타늄의 삽입한 11례중 1례의 경우 삽입후 12주에 경도의 골괴사 반응이 관찰되었으며 표면처리를 시행한 타이타늄을 삽입한후 전 례에서 골괴사가 관찰되지 않았다. 이는 수술적 조작에 의한 것으로 사료되었다. 섬유원세포의 증식은 시기에 관계없이 전 례에서 관찰되었으며,표면처리 여부 혹은 시간의 경과 정도와 관계가 없었다. 표면처리를 시행하지 않은 타이타늄의 삽입 후 6주에는 침윤정도 및 조직반응정도는 표면처리한 타이타늄의 삽입에 의해 통꼐적으로 유의하게 증가하였다. 그러나, 12주 및 26주 후에는 유의한 차이가 없었다. 다중희귀분석법의 단계별 투입방식을 이용하여 세포의 침윤율을 시간의 경과와 표면 처리여부에 따라 상관관계를 분석한 결과, 세포침윤율은 시간의 경과 및 표면처리를 하게 됨에 따라 감소하는 경향이 있었다. 조직 반응률의 정도도 침윤율과 유사한 양상을 나타내었다. 이상의 결과, 생체합금의 표면처리에 따라 골반응의 정도가 유의한 차이가 있었으므로 내고정 기구의 제작을 위해서는 보다 생체 적합성이 양호한 제작방법의 개발이 요구될 것으로 사려 되었다. The biocompatibility of the titanium has been estabilished through various experimental studies such as cell culture toxicity test, pyrogen test, mutagen test and others. In other to confirm biocompatibility after fabrication of titanium and to clarify the difference between the bone reaction after insertion of the lathed titanium rods and the bone reaction after insertion of the finished and polished rods, both rods were implanted into the proximal femur of a rabbit. Histologic reactions in the bone were observed according to the ASTM standards at the intervals of 6 weeks, 12 weeks and 26 weeks after implantation. The result were as follows : In 6 weeks after implantation of lathed titanium rods, inflammatory reactions, such as minimal degree infiltration of polymorphonuclear leukocytes and lymphocytes were observed in all cases. This was thought to be caused by surgical trauma. However, inflammatory cell infiltration was not seen after implantation of polished and finished rods in all cases. The cellular infiltration and the histologic reaction of the bone after implantation of lathed group were significantly more pronounced than those after implantation of the finished group. In 12 weeks after implantation of lathed rods, two of four cases revealed a minimal degree of cellular infiltration. No inflammatory cell infiltration was demonstrated after implantation of the finished group. The cellular infiltration and histologic reaction seemed to be more pronounced in the lathed group, but they were not significant statistically. At 26 weeks after implantation of the lathed and finished group, there was no cellular infiltration in both groups. New bone formation was observed up 26 weeks, and no difference between lathed titanium rods and finished titanium rods were apparent. Mild bone necrosis was observed in 1 case out of 11 cases in which lathed titanium rods were implanted. Bone necrosis was not observed in the finished titanium rod group. Fibrosis was observed in both groups, but differences were not significant between the experimental groups. In the lathed titanium rods group and the shorter interval group, inflammatory cell infiltration was significantly higher. Finished titanium rods and longer interval groups had markedly decreased tendences in histologic reaction ratings. As a conclusion, although certificated titanium might be safe to use, difference of biocompatibility were observed depending on the method of surface finish. By identifying biocompatibility as a long-term standardized animal study, we can develop progressed internal fixation device that is safe for human beings.