• Korean Journal of Materials Research
• /
• v.11 no.4
• /
• pp.247-250
• /
• 2001

We have fabricated and evaluated a new Si pin photodiode for red light detection with the web patterned $p^{+}$ -shallow diffused region in the light absorbing area. From the measurements of electro-optical characteristics under the bias of -5V, the junction capacitance of 4pF and the dark current of 235pA were obtained. When the 1.6㎼ optical power with peak wavelength of 670nm was incident on the device, the optical signal current of 0.48$\mu\textrm{A}$ and the responsivity of 0.30A/W were obtained. The fabricated device showed the improved sensitivity compared to the conventional circular type device and the maximum spectral response in a spectrum of 670~700nm. The web-patterned Si photodiode can be expected to have the good discrimination characteristics between digital signals in the application of red light optics.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.11
• /
• pp.29-35
• /
• 2015

The photo-response characteristics of polysilicon based metal-semiconductor-metal (MSM) photodetector structure, depending on deuterium treatment method, was analyzed by means of the dark-current and the light-current measurements. Al/Ti bilayer was used as a Schottky metal. Our purpose is to incorporate the deuterium atoms into the absorption layer of undoped polysilicon, effectively, for the defect passivation. We have introduced two deuterium treatment methods, a furnace annealing and an ion implantation. In deuterium furnace annealing, deuterium bond was distributed around polysilicon surface where the light current flows. As for the ion implantation, even thought it was a convenient method to locate the deuterium inside the polysilicon film, it creates some damages around polysilicon surface. This deteriorated the photo-response in our photodetector structure.

• Current Photovoltaic Research
• /
• v.9 no.4
• /
• pp.145-159
• /
• 2021

Light soaking (LS) stability in polymer solar cells (PSCs) has always been a challenge to achieve due to unstable photoactive layer-electrode interface. Especially, the electron transport layer (ETL) and photoactive layer interface limits the LS stability of PSCs. Herein, we have modified the most commonly used and robust zinc oxide (ZnO) ETL-interface using an organic dye molecule and a co-adsorbent. Power conversion efficiencies have been slightly improved but when these PSCs were subjected to long term LS stability chamber, equipped with heat and humidity (45℃ and 85% relative humidity), an outstanding stability in the case of ZnO/dye+co-adsorbent ETL containing devices have been achieved. The enhanced LS stability occurred due to the suppressed interfacial defects and robust contact between the ZnO and photoactive layer. Current density as well as fill factors have been retained after LS with the modified ETL as compared to un-modified ETL, owing to their higher charge collection efficiencies which originated from higher electron mobilities. Moreover, the existence of less traps (as observed from light intensity-open circuit voltage measurements and dark currents at -2V) are also found to be one of the reasons for enhanced LS stability in the current study. We conclude that the mitigation ETL-surface traps using an organic dye with a co-adsorbent is an effective and robust approach to enhance the LS stability in PSCs.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.27 no.2
• /
• pp.83-90
• /
• 1997

This study was performed to demonstrate the effect of linear or nonlinear contrast enhancement on subtraction images. Three different textures were radiograped on dental film. The first radiograph was taken without the presence of an object. the second, which showed trabucular bone, was taken of the molar area of a human. the third radiograph was taken of the coronal part of molars. Each film was digitized into a 1312 x 1024 pixel x 8 bit depth matrix by means of a Nikon 35 mm film scanner(LS-3510AF, Japan) with fixed gain and internal dark current correction to maintain constant illumination. The scanner was interfaced to a Macintosh Le ill computer(Apple Computer, Charlotte, N.C) This resulted in three pairs of images, including different textures-plain, bone and enamel. Digital regular, linearly and nonlinearly enhanced subtraction was performed. Computer software was ,used to simulate lesions in the shape of a 2D-Gaussian curve on each of a pair of images. The each subtraction images were presented in a random sequence to two groups of 10 observers(students and dentists). ROC analysis was used to compare observer performance. The following results were obtained ; 1. All of LCE subtraction, equalized subtraction and regular subtraction images of plain texture were diagnosed the best by far. 2. The data revealed a siginificant LCE effect in both the student group and the expert group. 3. Clinical expertise was a helphul factor for the observers in this study.

• Journal of the Korean Chemical Society
• /
• v.37 no.2
• /
• pp.213-219
• /
• 1993

The electrochemical spectral sensitization of $SnO_2$ electrodes with rhodamine B was studied. Photocurrent was measured in the presence of a variety of supersensitizers including ascorbic acid and KI. In the presence of ascorbic acid, the increase in the concentration of ascorbic acid, pH of the solution, or the potential applied to $SnO_2$ up to 0.6 V vs. SCE enhanced the photocurrent. However, ascorbic acid produced considerably high dark current due to its low reduction potential. On the other hand, KI produced low but stable photocurrent. The results, together with the solvent effect on the photocurrent, were taken into account to elucidate the mechanism of photosensitization in the presence of ascorbic acid or KI.

• Journal of The Korean Astronomical Society
• /
• v.38 no.2
• /
• pp.187-190
• /
• 2005

The Cosmic Evolution Survey (COSMOS) is a Hubble Space Telescope (HST) treasury project. The COSMOS aims to perform a 2 square degree imaging survey of an equatorial field in I(F814W) band, using the Advanced Camera for Surveys (ACS). Such a wide field survey, combined with ground-based photometric and spectroscopic data, is essential to understand the interplay between large scale structure, evolution and formation of galaxies and dark matter. In 2004, we have obtained high-quality, broad band images of the COSMOS field (B, V, r', i', and z') using Suprime-Cam on the Subaru Telescope, and we have started our new optical multi-band program, COSMOS-21 in 2005. Here, we present a brief summary of the current status of the COSMOS project together with contributions from the Subaru Telescope. Our future Subaru program, COSMOS-21, is also discussed briefly.

• The Journal of Korean Medicine
• /
• v.30 no.2
• /
• pp.127-132
• /
• 2009

Objectives: This study aimed to investigate the stability of a decoction using three herbal plants and their major components according to the storage conditions and periods. Materials and Methods: A three-herb mixture (1:1:1) of Glycyrrhiza uralensis Fischer, Artemisia capillaris Thunberg, and Poncirus trifoliata Rafinesqui was decocted and kept at room temperature ($25{\pm}2^{\circ}C$) or cold temperature ($4^{\circ}C$) for 0, 2, 4 or 8 weeks in liquid form in a plastic pack under dark conditions. At time points given, they were lyophilized. 200 mg of powdered samples were dissolved in 1 mL of 90% methanol and then applied to a high performance thin layer chromatography (HPTLC) with glycyrrhizin, 6,7-dimethoxycoumarin or poncirin for quantitative or qualitative analysis. Results: There were no gross changes in HPTLC-based compositional band-patterns of the three herbal mixture according to the storage conditions and period. The major components of each herb, glycyrrhizin, 6,7-dimethoxycoumarin and poncirin, showed slight time-dependent reduction in their contents both at room and cold temperature for 8 weeks. Conclusion: We could conclude that the current herbal decoction is generally safe for the stability at both RT or CT for at least 8 weeks. Nevertheless, we proposed that further advanced studies are required for more multiple herbal mixtures and longer storage periods.

• Journal of Pharmacopuncture
• /
• v.9 no.3 s.21
• /
• pp.117-129
• /
• 2006

Objectives : The aim of this study was to find optimal conditions for producing red ginseng from cultivated wild ginseng using the Turbo Mill. Methods : Characteristics of powdered cultivated wild ginseng based on various temperature settings of the Turbo Mill were observed, and changes in the content was measured by HPLC for various ginsenosides. Results : 1. The diameter of cultivated wild ginseng powder ground by the Turbo Mill was around 10${\mu}m$. 2. As the temperature rose, pressure, Specific Mechanical Energy(SME), and density decreased, whileas Water Solubility Index(WSI) increased. 3. As the temperature rose, super fine powder showed tendency to turn into dark brown. 4. Measuring content changes by HPLC, there was no detection of ginsenoside Rg3 and ginsenosideRg1, Rb1, and Rh2 concentrations decreased with increase in temperature. Conclusions : Super fine powder of cultivated wild ginseng produced by the Turbo Mill promotes easy absorption of effective ingredients by breaking the cell walls. Using this mechanism to produce red ginseng from cultivated wild ginseng, it yielded less than satisfactory results under the current experiment setup. Further researches are needed to verify more suitable condition for the production of red ginseng.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.11a
• /
• pp.146-146
• /
• 2009

최근에 광도전체와 형광체를 기반으로 평판형 디지털 방사선 검출기의 상업적 발전가능성에 많은 관심을 가지고 있다. 본 연구는 기존의 직접변환방식에 널리 사용되었던 비정질 셀레늄 (amorphous selenium) 기반의 디지털 방사선 검출기보다 높은 전기적신호 및 동작특성을 가지는 물질층을 제작하기 위해 High Purity (99.99%)의 상용화된 $PbI_2$를 특수용매에 담가두었다가 약 1시간동안 Biology 초음파 처리한 후 농축기를 사용하여 건조된 $PbI_2$를 3Roll-milling을 사용하여 미세크기의 Powder를 얻어내었다. 합성된 $PbI_2$ Powder를 PIB(Particle-in-Binder)법을 이용하여 전도성을 가진 ITO(Indium-tin-oxide)코팅된 유리판에 제작된 필름의 상부에 Magnetron sputtering system 을 사용하여 전극을 $1cm{\times}1cm$의 크기로 증착하였다. I-V 테스트를 통하여 X선 조사시 $PbI_2$필름의 Sensitivity, Dark current, SNR(signal-to-noise ratio)을 측정하여 필름의 전기적 검출 특성을 정량적으로 평가하였고 SEM(scanning electron microscope)을 통하여 입자의 크기를 관찰하였다.

• Current Research on Agriculture and Life Sciences
• /
• v.31 no.2
• /
• pp.94-100
• /
• 2013

An efficient plant regeneration protocol is developed for a standard-type chrysanthemum. When petal segments derived from flower buds (4 or 8cm in diameter) were used as the culture material, the highest shoot regeneration frequency (96%) was obtained on a Murashige and Skoog (MS) medium supplemented with 0.5 mg/L IAA, 2 mg/L BA, 3% sucrose, and a 0.8% agar. Pre-culturing the explants under dark conditions for 14 days produced better results for the shoot regeneration frequency than the explants cultured under a continuous 16 h photoperiod ($40{\mu}molm^{-2}s^{-1}$). The shoot regeneration frequency ranged from 19.0% for the Shinmato cultivar to 89.1% for the Baeksun cultivar. Activated charcoal (0.2%) enhanced the root formation of the regenerated shoots in a hormone-free MS medium. The rooted plantlets were acclimatized and successfully established in a greenhouse.