• 한국작물학회지
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• 제49권1호
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• pp.41-45
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• 2004

We have developed and tested a new method for nondestructive estimation of chlorophyll- and nitrogen-contents in rye leaf. It was found that the relation-ships among nitrogen, chlorophyll content and fresh weight were significantly positive correlated. Nitrogen and chlorophyll content were positively correlated whereas correlation coefficients among R, G, R-B and G-B on the basis of photo-numerical values were negative. We have found that R/(R-B) obtained from data of digital camera is the best criterion to estimate the chlorophyll content of leaves. The regression curves of the relation between R/(R-B) and chlorophyll content were also calculated from the data collected on cloudy days. The coefficients of determination ($\textrm{r}^2$) were ranged from 0.33 to 0.99. In this study, the accuracy in estimating chlorophyll content from the color data of digital camera image could be improved by correcting with R, G, and B values. It is suggested that, for practical purposes, the image values estimated with sufficient accuracy using a portable digital camera can be applied for determining chlorophyll content and nitrogen status in plant leaves.

• Advances in aircraft and spacecraft science
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• 제7권1호
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• pp.41-52
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• 2020

The effect of relaxation times is studied on plane waves propagating through semiconductor half-space medium by using the eigen value approach. The bounding surface of the half-space is subjected to a heat flux with an exponentially decaying pulse and taken to be traction free. Solution of the field variables are obtained in the form of series for a general semiconductor medium. For numerical values, Silicon is considered as a semiconducting material. The results are represented graphically to assess the influences of the thermal relaxations times on the plasma, thermal, and elastic waves.

• 한국광학회지
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• 제3권4호
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• pp.273-279
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• 1992

수치제어 공작기계와 로보트 등에서의 위치판독장치는 핵심적인 자동화부품이다. 수치제어용 위치판독장치인 광학식 에코더의 제조기술의 국산화를 위하여 부분 공정을 개발하였다. Microlithography 가공기술을 이용하여 유리 기저판 위에 정밀눈금을 가공하였다. 눈금가공 공정은 많은 단계의 과정을 거쳐 이루어 진다. 박막두계, 수지코팅, 건조온도, 노광시간, 부식시간 등 공정변수들의 최적조건을 찾아내고 각 공정변수에 따른 눈금품직과의 관계를 규명하였다.

• 한국전산유체공학회지
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• 제13권4호
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• pp.66-71
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• 2008

This research computes the viscous flow field and aerodynamics around the model of a commercial passenger airplane, Boeing 747-400, which cruises in transonic speed. The configuration was realized through the reverse engineering based on the photo scanning measurement. In results, the pressure coefficients at the several wing section on the wing surface of the airplane was described and discussed to obtain the physical meaning. The lift coefficient increased almost linearly up to $17^{\circ}$. Here the maximum lift occurred at $18^{\circ}$ according to the angle of attack. And the minimum drag is expected at $-2^{\circ}$. The maximum lift coefficient occurred at the Mach number 0.89, and the drag coefficient rapidly increased after the Mach number of 0.92. Also shear-stress transport model predicts slightly lower aerodynamic coefficients than other models and Chen's model shows the highest aerodynamic values. The aerodynamic performance of the airplane elements was presented.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.312-312
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• 2011

In SiH4/H2 discharge for growth process of hydrogenated amorphous silicon (a-Si:H), silane polymers, produced by SiH2 + Sin-1H2n ${\rightarrow}$ SinH2n+2, have no reactivity on the film-growing surface. However, under the SiH2 rich condition, high silane reactive species (HSRS) can be produced by electron collision to silane polymers. HSRS, having relatively strong reactivity on the surface, can react with dangling bond and form Si-H2 networks which have a close correlation with photo-induced degradation of a-Si:H thin film solar cell [1]. To find contributions of suggested several external plasma conditions (pressure, frequency and ratio of mixture gas) [2,3] to suppressing productions of HSRS, some plasma characteristics are studied by numerical methods. For this study, a zero-dimensional global model for SiH4/H2 discharge and a one-dimensional particle-in-cell Monte-Carlo-collision model (PIC-MCC) for pure SiH4 discharge have been developed. Densities of important reactive species of SiH4/H2 discharge are observed by means of the global model, dealing 30 species and 136 reactions, and electron energy probability functions (EEPFs) of pure SiH4 discharge are obtained from the PIC-MCC model, containing 5 charged species and 15 reactions. Using global model, SiH2/SiH3 values were calculated when pressure and driving frequency vary from 0.1 Torr to 10 Torr, from 13.56 MHz to 60 MHz respectively and when the portion of hydrogen changes. Due to the limitation of global model, frequency effects can be explained by PIC-MCC model. Through PIC-MCC model for pure SiH4, EEPFs are obtained in the specific range responsible for forming SiH2 and SiH3: from 8.75 eV to 9.47 eV [4]. Through densities of reactive species and EEPFs, polymerization reactions and production of HSRS are discussed.