• Title, Summary, Keyword: Light reduction rate

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Solar Tracking Performance using a Heliostat and Uniform Irradiation of LED Light for a Plant Factory (식물공장의 헬리오스탯을 이용한 태양광 추적성능 및 LED 균일광 조사)

  • Koo, Kyung-Wan;Kim, Tae-Jin;Kim, Youngshik;Ryu, Bong-Jo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.12
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    • pp.1761-1767
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    • 2015
  • This paper deals with the solar tracking performance using a small heliostat, the light reduction rate of the sun light, and the performance of uniform irradiation of LED light for a plant factory. A high precision encoder is attached to the heliostat to improve tracking accuracy. As a result, our heliostat-based solar tracking systems track efficiently the movement of the sun light in experimental tests. The reduction rate of the sun light in the plant factory is then measured by using an illumination sensor. The average reduction rate is 4.29%, which represents lower light reduction rates. In uniform irradiation tests of LED light, sixteen points are measured, and overall deviations of irradiation were within eight percents.

Visible light-induced reduction of Cr(VI) in cationic micelle solution

  • Kyung, Hyunsook;Cho, Young-Jin;Choi, Wonyong
    • Rapid Communication in Photoscience
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    • v.4 no.3
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    • pp.73-75
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    • 2015
  • Cr(VI) reduction was successfully achieved in the presence of cationic micelles (CMs) under visible light illumination. Micelle formation of cationic surfactants seems to be critical in Cr(VI) reduction. Cr(VI) was reduced very fast above the critical micelle concentration (cmc) of CTAB solutions, but was not reduced at all either below or around the cmc of CTAB. The reduction rate of Cr(VI) was enhanced in the absence of dissolved oxygen, supporting that the removal of Cr(VI) should be achieved via a reductive pathway. When CTAB was substituted by Brij 35 or SDS, the reduction of Cr(VI) was negligible. This indicates that the electrostatic interaction between Cr(VI) and headgroups of surfactants is important in the visible light-induced Cr(VI) reduction in micellar solutions.

Pigment Reduction to Improve Photosynthetic Productivity of Rhodobacter sphaeroides

  • Kim, Nag-Jong;Lee, Jeong-Kug;Lee, Choul-Gyun
    • Journal of Microbiology and Biotechnology
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    • v.14 no.3
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    • pp.442-449
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    • 2004
  • Improving the light utilization efficiency of photosynthetic cells in photobioreactors (PBRs) is a major topic in algal biotechnology. Accordingly, in the current study we investigated the effect and suitability of photosynthetic pigment reduction for improving light utilization efficiency. The light-harvesting complex II (LH-II) genes of Rhodobacter sphaeroides were removed to construct a mutant strain with less pigment content. The mutant strain exhibited a slower growth rate than the wild-type under a low light intensity, while the mutant grew faster under a high light intensity. In addition, the specific absorption coefficient was lower in the mutant due to its reduced pigment content, thus it seemed that light penetrated deeper into its culture broth. However, the distance (light penetration depth) from the surface of the PBR to the compensation point did not increase, due to an increase in the compensation irradiance of the mutant strain. Experimental data showed that a reduced photosynthetic pigment content, which lessened the photoinhibition under high-intensity light, helped the volumetric productivity of photosynthetic microorganisms.

Interactive Effects of Ozone and Light Intensity on Platanus occidentalis L. Seedlings

  • Kim, Du-Hyun;Han, Sim-Hee;Lee, Kab-Yeon;Kim, Pan-Gi
    • Journal of Korean Society of Forest Science
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    • v.97 no.5
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    • pp.508-515
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    • 2008
  • Sycamore (Platanus occidentalis L.) seedlings were grown under low light intensity and ozone treatments to investigate the role of the light environment in their response to chronic ozone stress. One-year-old seedlings of Platanus occidentalis L. were grown in pots for 3 weeks under low light (OL, $150{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and high light (OH, $300{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) irradiance in combination with 150 ppb of ozone fumigation. After three weeks of ozone and light treatment, seedlings were placed in ozone free clean chamber for 3 weeks for recovery from ozone stress with same light conditions to compare recovery capacity. Ozone fumigation determined an impairment of the photosynthetic process. Reduction of leaf dry weight (14%) and shoo/root ratio (17%) were observed in OH treatment. OL treatment also showed severe reductions in leaf dry weight and shoot/root ratio by 48% and 36% comparing to control, respectively. At the recovery phase, OH-treated plants recovered their biomass, whereas OL-treated plant showed reduction in leaf dry weight (52%) and shoot/root ratio (49%). OH-treated plants reached similar relative growth rate (RGR) comparing to control, whereas OL-treated plants showed lower RGR in stem height. However, there were no significant differences in response to those treatments in stem diameter RGR at the recovery phase. Ozone treatment produced significant reduction of net photosynthesis in both high and low light treatments. Carboxylation efficiency and apparent quantum yield in OL-treated plants showed significant reductions rate to 10% and 45%, respectively. At the recovery stage, ozone exposed seedlings under high light had similar photosynthetic capacity comparing to control plants. Antioxidant enzymes activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) were increased in ozone fumigated plants only under low light. The present work shows that the physiological changes occur in photosynthesis-related parameters and growth due to ozone and low light stress. Thus, low light seems to enhance the detrimental effects of ozone on growth, photosynthesis, and antioxidant enzyme responses.

Effect of Rolling Conditions on Microstructure and Mechanical Properties of HCC AZ31 Alloy Plate (압연조건에 따른 AZ31 연주판재의 미세조직 및 기계적 특성 변화)

  • Kim, Young Min;Chun, Eun Young;Yim, Chang Dong;You, Bong Sun;Lee, Je-hyun
    • Korean Journal of Metals and Materials
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    • v.46 no.4
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    • pp.189-198
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    • 2008
  • The changes in microstructure and mechanical properties of AZ31 alloy subjected hot-rolling process were investigated. The AZ31 plates fabricated by horizontal continuous casting process were prepared and have hot-rolled from 30 mm to 1 mm in thickness under different processing conditions. At the rolling temperature of $400^{\circ}C$, little surface and side crack was observed up to 20% reduction rate. As total reduction and reduction rate increase to more than 75% and 20% pass, respectively, Grains were more uniformly refined through overall thickness, and particularly lots of shear bands were appeared to be inclined at less than $20^{\circ}C$ along the rolling direction. Average grain size of less than $5{\mu}m$ and tensile properties of YS ${\geq}$ 250 MPa, UTS ${\geq}$ 300 MPa and El. ${\geq}$ 13% were acquired for hot-rolled AZ31 sheets without post-heat treatment. Maximum intensity of (0002) pole figure was decreased with an increase in reduction rate, indicating the improvement of texture by means of high reduction rate.

Effects of Light and Nitrogen on the Growth of Pokeberry (미국자리공의 생장에 미치는 광과 질소의 영향)

  • 박범진;박용목;최기룡
    • The Korean Journal of Ecology
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    • v.21 no.4
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    • pp.329-335
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    • 1998
  • The growth of Phytolacca L. grown under three light regimes at three nutrient concentrations was analyzed. The effect of shading treatment on plnat growth was greater than that of nutrient treatment. Plant dry mass increased more than 5-fold during 21 days under 33% and 100% irradiances, whereas that was strongly reduced under 8% irradiance. Net assimilation rate decreased with plant growth irrespective of light and nutrient treatments, though the highest net assimilation rate was shown under 100% irradiance. Under 33% irradiance leaf area in plants supplied with nutrient solution increased to such extent as to compensate reduction in net assimilation rate, whic maintains almost identical growth rate with that under 100% irradiance. The relatonship between total plant nitrogen and leaf nitrogen content was dependent on the growth irradiance. Moreover, leaf nitrogen and specific leaf weight were also changed depending on the light and nutrient conditions. Based on these findings, it is suggested that the adaptive characteristics of Pokeberry plant to light and nutrient conditions may contribute to rapid extension of Pokeberry habital in Korea rocently.

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Dynamic Characteristics of a Urea SCR System for NOx Reduction in Diesel Engine

  • Nam, Jeong-Gil;Choi, Jae-Sung
    • Journal of the Korean Society of Marine Engineering
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    • v.31 no.3
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    • pp.235-242
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    • 2007
  • This paper discusses dynamic characteristics of a urea-SCR (Selective Catalytic Reduction) system. The urea flow rate to improve NOx conversion efficiency is generally determined by parameters such as catalyst temperature and space velocity. The urea-SCR system was tested in the various engine operating conditions governing the raw NOx emission levels, space velocity. and SCR catalyst temperature. These experiments include cold-transients to determine catalyst light-off temperature and urea flow rate transients. Likewise. ammonia storage dynamics was also investigated. The cold-transient results indicate the light-off temperature of the catalysts used in these experiments was $200-220^{\circ}C$. The ammonia storage and urea flow rate transients all indicate very slow dynamics (on the order of seconds) which presents control challenges for mobile applications. The results presented in this paper should provide an excellent starting point in developing a functional in-vehicle urea-SCR system.

Dyeability and Functionality of Wool Fabrics Dyed with Zizania latifolia Turcz. extract (줄풀염색에 의한 모직물의 염색성과 기능성)

  • Ko, Eunsook;Lee, Hyesun
    • Fashion & Textile Research Journal
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    • v.21 no.2
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    • pp.231-236
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    • 2019
  • This study investigated the proper dyeing conditions, color fastness and functionality of wool fabrics dyed with Zizania latifolia Turcz. We also tried to improve light fastness through treatment with benzophenone ultraviolet absorber. The dyeing of wool fabrics using Zizania latifolia Turcz was good even without pretreatment or mordanting treatment. Optimal wool fabric dyeing conditions were colorant concentration of 200% (o.w.f.), dyeing temperature of $100^{\circ}C$, dyeing time of 80 minutes and a dye bath pH of 3. Color fastness of dyed wool fabrics to washing, rubbing, perspiration and light was 4-5, 5, 4-4-5 (acidic), 4-5 (alkaline) and 2 respectively. The results after treatment with ultraviolet absorber for improving the fastness of daylight were improved to 3-4 grade. The UV protection rate were increased after dyeing and the deodorization of ammonia gas improved to 98%. Bacterial reduction rate (Staphylococcus aureus) of wool fabrics was excellent at 99.9%. All dye fastness (except for light fastness) was excellent; in addition, the functionality of wool fabrics dyed with Zizania latifolia Turcz also improved. The results are expected to be applied to various fields because they indicate excellent results after treatment with ultraviolet absorber for improving the fastness of daylight.

Dyeing of Natural Fibers with Extract of Ginkgo biloba Bark(II) - Fastness and Functional Characteristics of Dyed Fabrics - (은행나무 수피 추출액에 의한 천연섬유의 염색(II) -염색물의 견뢰성 및 기능성-)

  • 최순화;조용석
    • Textile Coloration and Finishing
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    • v.13 no.6
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    • pp.359-366
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    • 2001
  • In this study, wool, silk and cotton fabrics were dyed with natural dyes derived from Ginkgo biloba bark using various mordants, and their dyeabilities were discussed. Additionally the fastness to washing, perspiration, light, rubbing, and drycleaning were investigated. And the effects of bacteria reduction and UV-B protection rate were also checked. The optimum dyeing condition of the colorants extracted from the Ginkgo biloba bark was three repeated dyeing at$95^\circ{C}$ for 1 hr. by using post mordanting. Mordanting improved the fastness to washing, Perspiration and drycleaning, but the fastness to light and rubbing were not increased. The bacteria reduction rate of the wool fabric increased drastically by dyeing with extract of Ginkgo biloba bark and its effect maintained after repeated washing and drycleaning. UV-B protection rate of the natural fibers increased by dyeing with extract of Ginkgo biloba bark and the dyed wool fabric was the best of the three fabrics.

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A Cost Reduction Effects Analysis on Automatic Operation of Light Rail (경량전철 무인자동운전의 비용 절감 효과 분석)

  • 민재홍
    • Proceedings of the KSR Conference
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    • pp.63-70
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    • 2000
  • Light Rail is highlighted for its construction cost and operation & maintenance cost in Korea. However, lack of analysis on driverless operation effect causes many disputes. In this paper, using latest driverless operation cost data. analysed cost reduction effect of it, with comparing present KNR's metropolitan subway signal system. It showed there is enough economic appropriateness B/C 1.241 on interest rate 6%, 1.076 on 8% and 0.943 on 10%, though it couldn't include passenger travel time value.

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