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IEC1400-1 국제표준을 적용한 대형 수평축 풍력발전용 회전날개의 설계개선
공창덕,방조혁,정종철,감명훈,정석훈,장병섭,안주연 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.2
풍력 터빈회전날개의 설계시 구조적 형상을 결정하는 예비설계 단계에서 종전에는 여러 가지 다양한 경우의 설계를 수행하여 이중 적합한 경우을 채택하는 시행착오 방법은 많은 설계시간을 요하였으나, 본 연구에서는 이 같은 설계시의 비효율적 요소를 배제하고자 적층판 이론을 기초로 한 설계프로그램을 이용하는 설계기법을 계발함으로서 설계절차를 개선하였다. 개선된 설계절차에 따라 국제표준 설계규격 IEC1400-1에서 규정한 각 경우의 하중해석과 응력, 변형율 및 변형한계를 설정한 후, 단순화한 복합재 회전날개 구조에 혼합법칙과 주 응력 설계기법을 이용하여 복합재 구조의 형상을 정하였다. 설계된 구조는 본 연구를 통해 개발된 적층판 이론을 기초로 한 프로그램을 이용하여 강도 및 좌굴에 대한 구조의 안정성을 확인하여 상세설계 과정 시 소요되는 시간을 최소화하였다. 설계된 구조는 표피 등을 고려하여 수정 설계한 후 유한요소법을 이용하여 응력, 변형율, 변위, 고유진동수, 좌굴안정성, 피로수명등을 해석하여 국제 표준규격의 만족여부를 확인하였다. Because the previous design procedure for the composite wind turbine blade structure using trial and error method takes long time, a improved design procedure by using the program based on classical laminate theory was proposed to reduce the inefficient element. According to the improved design procedure, limitation of strains, stresses and displacements specified by international standard specification IEC1400-1 for the composite wind turbine blade were applied to sizing the structural configuration by using the rule of mixture and the principal stress design technique with a simplified turbine blade. Structural safety for strength and buckling stability was confirmed by the developed analysis program based on the laminate theory to minimize the design procedure. After modifying the preliminary design result with additional structural components such as skin, foam sandwich and mounting joints, stresses, strains, displacements, natural frequency, buckling load and fatigue life were analyzed by the finite element method. Finally these results were confirmed by comparing with IEC1400-1 specification.
DNA barcoding and phylogenetic analysis in Chrysanthemum
WooJu Hong,Gang Li,Ayeaye Khaing,Khandakar M.D. Rayhanul Kabir,Yong-Jin Park 한국육종학회 2012 한국육종학회 심포지엄 Vol.2012 No.07
The plant family chrysanthemum is known for its medicinal, ornamental, and economic purposes. Owing to its economic and biological significance to the difficult identification based on morphological characters, it is useful to develop DNA barcodes. DNA sequence data enable not only the inference of phylogenetic relationships but also provide an efficient method for species-level identifications under terms DNA barcoding or DNA taxonomy. The purpose of this study is to evaluate the utility of DNA barcoding in discriminating Chrysanthemum species. Four cpDNA regions (matK, rpoC, rpoB, trnH-psbA) and one nuclear (ITS) marker have sequenced from 28 specimens of 11 species from 4 genera of Chrysanthemum which were collected from 5 provinces in Korea. Comparisons of within and between species levels of sequence divergence showed that genetic variation between species exceeds variation within species.
Patil, D.S.,Pawar, S.A.,Devan, R.S.,Mali, S.S.,Gang, M.G.,Ma, Y.R.,Hong, C.K.,Kim, J.H.,Patil, P.S. Elsevier Sequoia 2014 Journal of electroanalytical chemistry Vol.724 No.-
The composite thin films of Silver-activated carbon/polyaniline (Ag-AC/PANI) have been deposited on stainless steel substrates by a facile dip coating technique. The formation of Ag-AC/PANI electrode is analyzed by Fourier transform infrared, Fourier transform-Raman and X-ray photoelectron spectroscopy techniques. Field Emission Scanning Electron Microscopy revealed the presence of Ag nanoparticles on the porous spongy background of PANI. The highest specific capacitance of 567Fg<SUP>-1</SUP>at 5mVs<SUP>-1</SUP> and energy density of 86.30Whkg<SUP>-1</SUP> at 1mAcm<SUP>-2</SUP> is observed for the Ag-AC/PANI indicating positive synergistic effect of silver, activated carbon and PANI. In which silver nanoparticles help in improving the electronic conductivity and activated carbon enhances the electrochemical stability of the PANI electrodes.
장애인 실업자의 취업에 영향을 미치는 결정요인에 관한 연구
강봉석(B. S. Gang),염동문(D. M. Yeum) 한국재활복지공학회 2015 재활복지공학회논문지 Vol.9 No.2
본 연구는 장애인고용패널조사 1차년부터 5차년도까지 자료를 사용하여 콕스비례위험모델을 적용하여 분석하였다. 연구목적은 실업기간에 따른 장애인 실업자의 취업에 영향을 미치는 중요한 요인을 분석하여 장애인의 취업지원에 필요한 정책적 제언을 하고자 하였다. 분석결과, 인구사회학적요인과 장애요인, 사회환경요인을 모두 고려한 모델이 검증되었으며, 장애인의 주관적 SES가 높을수록 장애인 실업자의 취업률이 높아지며, 중증장애인에 비해 경증장애인이 취업에 유리하였으며, 상대적으로 근로외 소득이 낮을수록 취업률이 높은 것으로 나타났다. 이러한 결과를 토대로 연구의 제한점과 함의를 제안하였다. This study applied a cox proportional hazard model for analysis, using data of the Panel Survey of Employment for the Disable from the first to fifth years. The purpose of the study is to make a policy suggestion necessary for the support of employment for the disabled, by analyzing important factors affecting employment of the unemployed disabled according to the unemployment period. Results of the analysis were: a model that considered all the sociodemographic, obstructive and social environmental factors was verified; the higher subjective SES of the disabled, the higher employment rate of the unemployed disabled; compared to the severely disabled, the slightly disabled had more advantages for employment; and relatively the lower unearned income, the higher employment rate. This study suggested based on these results limitations and implications of the study.
The study of light waveguide effects on ZnO nanorod arrays
Kim, T. U.,Gang, M. G.,Kim, J. A.,Moon, J. H.,Kim, D. G.,Kim, S. H.,Ki, H. C.,Choi, J. h.,Kim, J. H. Springer Science + Business Media 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.2
<P>Two different types of ZnO nanorods (hexagonal pyramid-shaped nanorod and hexagonal prism-shaped nanorod) were integrated on light emitting diodes (LEDs) for the investigation of light waveguide effects, which were evaluated using electroluminescence (EL) and current-voltage (I-V) characteristics. EL intensity in LEDs with hexagonal prism-shaped ZnO nanorod arrays were improved by 18% while EL intensity in LEDs with hexagonal pyramid-shaped ZnO nanorods were reduced by 25% compared to bare LEDs. 3D-finite dimension time domain (3D-FDTD) programs were used to simulate the light waveguide effect on the two different shapes of ZnO nanorods. In addition, photonic crystals (PCs) effects in ZnO nanorod arrays were simulated to verify the light waveguide effect. It was found that light in a hexagonal prism-shaped ZnO nanorod propagated from the bottom to the top end. However, the light in a hexagonal pyramid-shaped ZnO nanorod was dissipated on the lateral face. The light extraction efficiency in ZnO nanorod arrays was dominated by the top end shape and planar density of ZnO nanorods.</P>