• 한국환경과학회지
• /
• 제26권4호
• /
• pp.543-547
• /
• 2017

Normalized Difference Vegetation Index (NDVI) has played an important role in assessing green plant biomass through remote sensing on global scale since the early 1970s. The concept of NDVI is based on the fact that green plants show higher reflection in near-infrared region than in visible region of the electromagnetic spectrum. However, it is well known that the relocation of chloroplasts in plant leaf cells may dramatically change the optical properties of plant leaves. In this study I traced the changes in the reflectance and transmittance properties of Tobacco leaves at the wavelengths of 660 and 800 nm after a sudden increase in light intensity. The results showed that NDVI of leaves gradually decreased from 72.7% to 69.9% when exposed to a sudden increase in light intensity from 30 to $1,200{\mu}mol/m^2{\cdot}s$. This means that the error resulting from the physiological status of the plant should be accounted for a more precise understanding of ground truth corresponding to the data from the remotely acquired images.

• 한국전기전자재료학회논문지
• /
• 제20권8호
• /
• pp.711-715
• /
• 2007

Properties of organic light-emitting diodes (OLEDs) with aluminum-doped zinc oxide (ZnO:Al) anodes showed different behaviors from OLEDs with indium tin oxide (ITO) anodes according to driving conditions. OLEDs with ITO anodes gave higher current density and luminance in lower voltage region and better EL and power efficiency under lower current density conditions, However, OLEDs with ZnO:Al anodes gave higher current density and luminance in higher voltage region over about 8V and better EL and power efficiency under higher current density over $200mA/cm^2$. These seemed to be due to the differences in conduction properties of semiconducting ZnO:Al and metallic ITO. OLEDs with ZnO:Al anodes showed nearly saturated efficiency under high current driving conditions compared with those of OLEDs with ITO anodes. This meant better charge balance in OLEDs with ZnO:Al anodes. These properties of OLEDs with ZnO:Al anodes are useful in making bright display devices with efficiency.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.97-98
• /
• 2008

n-ZnO/p-Si heterostructure is a good candidate for ZnO-based heterojunction light emitting diodes(LED) because of its competitive price and lower driving voltage. However, the conventional LED shows much lower extraction efficiency, because it has small top contact and large backside contact. In this structure, the injected current from the top contact enters the active region underneath the top contact. Thus, the emitted light is hindered by the opaque top contact. This problem can be solved by using a current-blocking layer(CBL) that prevents the current injection into the active region below the top contact.

• Applied Microscopy
• /
• 제20권2호
• /
• pp.23-36
• /
• 1990

Several types of the epithelial cells were classified by ultrastructural observation through transmission electron microscope in the rat epididymis. Ultrastructural studies showed that the principal cells, basal cells and narrow cells are located in all the regions of the epididymis and the light cells are present only in the corpus and cauda epididymis. It was observed that the columnar epithelial cells like the principal cells, light cells and narrow cells contain several secretory vesicles and there are halo cells migrating in the several regions. The basal cells showed the elliptical forms in the caput and corpus region and the global forms in the cauda region.

• 대한수의학회지
• /
• 제26권1호
• /
• pp.19-30
• /
• 1986

Endocrine cells were observed in the gastrointestinal tract of the squirrels by light microscopy using Grimelius and Masson-Hamperl silver impregnation, and in the stomach and duodenum by electron microscopy. Light microscopically, argyrophil cell decreased gradually in number in the pyloric region and ileum, stomach, duodenum and jejunum and rectum in the order listed. Argentaffin cells were moderately distributed in the stomach, pyloric region and duodenum, while absent in the jejunum, ileum and rectum. Five kinds of cell types, EC, ECL, D, $D_1$ and G cells were identified in the stomach and three kinds of cell types, S, $EC_1$ and $EC_2$ were also identified in the duodenum by electron microscopy. A cilium noted in the cytoplasm of $D_1$-type cell. The species differences in the distribution, size and structure of the secretory granules were discussed.

• Current Optics and Photonics
• /
• 제2권1호
• /
• pp.85-89
• /
• 2018

This paper presents a new, efficient hybrid photonic-plasmonic structure. The proposed structure efficiently and with very high accuracy combines the resonant mode of a low-mode-volume photonic-crystal nanocavity with a bowtie nanoantenna's plasmonic resonance. The resulting enormous enhancement of light intensity of about $1.1{\times}10^7$ in the gap region of the bowtie nanoantenna, due to the effective optical-resonance combination, is realized by subtle optimization of the nanocavity's optical characteristics. This coupled structure holds great promise for many applications relying on strong confinement and enhancement of optical field in nanoscale volumes, including antennas (communication and information), optical trapping and manipulation, sensors, data storage, nonlinear optics, and lasers.

• 천문학회보
• /
• 제36권2호
• /
• pp.149.2-149.2
• /
• 2011

We performed the cross-correlation analysis on energy-dependent light curves of the Z-type source GX 5-1. We observed X-ray delays of a few hundred seconds between hard (16-30 keV) and soft (2-5 keV) X-ray light curves. During these phenomena, the centroid frequency of horizontal branch oscillation (HBO) was found to shift to lower or higher frequency indicating towards the dynamical movement of a Compton cloud or an inner disk front. Both eastern and western approaches were used to unfold the X-ray continuum and systematic changes were observed in soft and hard X-ray spectral components. Simultaneous energy spectral and power density spectral study shows that the production of HBOs is closely related to the Comptonizing region rather than the accretion disk. We discuss the results in the context of re-condensation of coronal material in the inner accretion disk region.

• Bulletin of the Korean Chemical Society
• /
• 제23권12호
• /
• pp.1749-1753
• /
• 2002

The effect of concentration fluctuations on the changes of azimuth and ellipticity are analytically obtained in a binary chiral liquid mixture, when the incident light is completely linearly polarized above (or below) the horizontal at 45°. The important results are as follows;(1) When the binary liquid is in the critical region far from the cr5itical point, the ellipticity change is proportional to isothermal compressibility factor and the fifth order of frequency and shows the logarithmic divergence. (2) In the case that the system is in the critical region far from the critical point, the azimuth change is solely due to the molecular contribution. As the system approaches to the critical point, the effect of fluctuations becomes important. If it is in the extreme close to the critical point, the term due to the concentration fluctuations is comparable to or larger than the molecular contribution.

• 한국전자파학회논문지
• /
• 제9권3호
• /
• pp.338-346
• /
• 1998

천정에 부착한 구상 리플렉터와 송수신 공용 양선 원편파 안테나를 조합하여 옥내무선통신망을 실현하려 한 다. 먼저, 시스댐 실현에 앞서, 본 논문에서는 도체구의 산란패턴을 벡터 구파동함수를 이용한 계산 및 실측한 결과 후방산란영역(이하 명영역이라 칭함)에서 안정한 전방향 산란레벨 유지를 확인하였으며 13 dB 이상의 펀파분리도도 확보되었다. 따라서 완전도체구의 명영역 전방향 산란특성을 기반으로 구상 리플랙터가 제안 힌 옥내무선통신시스템에 유효함음 확인했다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 추계학술대회 논문집
• /
• pp.145-148
• /
• 2000

In contrast to the $\pi$ -conjugated polymers which typically absorb light only in the visible spectral region, the $\sigma$-conjugated polymers can be used as efficient material absorbing light in the UV region. In this work, the electronic and optical properties of I$_2$-doped $\sigma$ -conjugated poly (methyl-phenylsilylene) (PMPSi) polymer were investigated. DC conductivity up to 1.2$\times$10$^{-4}$ S/cm was obtained by I$_2$-doping. In UV/Vis absorbance spectrum, a new peak was observed near 370 nm, which was explained by polaron model. The photoluminescence (PL) intensity decreased with increasing degree of I$_2$-doping, and the Infrared (IR) spectrum analysis revealed that the dopants are not directly coupled to the polymer, but effect motions of the methyl and phenyl groups.