• Title/Summary/Keyword: dark energy

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Optimization of bio-$H_{2}$ production from acid pretreated microalgal biomass (미세조류로부터 바이오 수소 생산을 위한 산(acid) 전처리의 최적화)

  • Yun, Yeo-Myeong;Jung, Kyung-Won;Kim, Dong-Hoon;Oh, You-Kwan;Shin, Hang-Sik
    • Journal of the Korea Organic Resources Recycling Association
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    • v.20 no.1
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    • pp.78-86
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    • 2012
  • In this study, dark fermentative hydrogen production (DFHP) from acid pretreated microalgal biomass was optimized with via statistical experimental design. Acid concentration and reaction time were varied from 0.1 to 3% (v/w) and 10 to 60 min with substrate concentration of 76 g dry cell weight (dcw)/L and initial pH of 7.4, respectively. During the fermentation, pH was not controlled. The optimal condition was found that at $H_{2}$ yield reached to 37.3 mL $H_{2}/g$ dcw at 1.2% HCl and 48 min. Through regression analysis, it was found that $H_{2}$ yield was well fitted by a quadratic polynomial equation ($R^{2}$=0.95). HCl concentration was the most significant factor influencing DFHP. The results of ANOVA verify that HCl concentration was the most significant factor influencing DFHP.

Development of Leaf Mutant Cultivars of Cymbidium goeringii by Ethyl-methane-sulfonate (EMS) Treatment. (Ethyl-methane-sulfonate(EMS) 처리에 의한 춘란 잎 돌연변이 품종의 개발)

  • Shin, Yun-Ho;Song, In-Ja;Kang, Eun-Jung;Bae, Tae-Woong;Sun, Hyeon-Jin;Kang, Si-Young;Lim, Pyung-Ok;Lee, Hyo-Yeon
    • Korean Journal of Plant Resources
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    • v.24 no.1
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    • pp.17-22
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    • 2011
  • This study was for developing leaf chlorophyll mutant cultivars of Cymbidium goeringii by ethyl-methanesulfonate(EMS) treatment. Chlorophyll mutant rhizomes were easily produced by 0.2% EMS treatment in this genus. Among the mutants, they became dark brown about 50% of the rhizomes. When the dark-brown rhizomes were cultured in a solidified MS medium, new rhizomes were formed from part of the old ones. Chlorophyll mutant rhizomes were obtained from subcultured meristem tissues of newly-formed rhizomes. The rhizomes were cut and subcultured for a year and then became mutant plants. As the results, they produced 4 kinds of leaf mutant cultivars; zigzag-striped, comb-striped, net-striped, and dwarf types, indicating that the EMS treatment in the rhizome could produce versatile leaf chlorophyll regulating mutants. These results suggest that our method is useful for developing leaf mutant cultivars of this planta which they are estimated as higher commercial values.

Ergosterol Contents and Enzymatic Characteristics of Lentinula edodes During Culture and Fruiting Periods (표고 균주의 배양 기간과 자실체 발생 기간에 따른 에르고스테롤 변화와 효소적 특성)

  • Kim Myungkil;Yoon Kabhee;Bak Wonchull;Park Hyun;Choi Joonweon;Lee Jaewon;Lee Bonghun
    • Journal of Korea Foresty Energy
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    • v.23 no.2
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    • pp.21-28
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    • 2004
  • Three different strains of Lentinula edodes, Sanlim 5-Ho, Sanlim 6-Ho and Nongki 3-Ho, were cultured in the sawdust media of Mongolian oak(Quercu mongolica Fisch) for 90 days under dark and light conditions(each 30 days) and fruiting period(30 days). Weight loss of sawdust media was determined after fungal cultures and the contents of ergosterol in fungal mycelia were quantified by HPLC analysis followed by solvent extraction. Compared with the two other fungal strains$(8\%)$, weight loss of Sanlim 5-Ho was slightly lowered to $7\%$. The level of ergosterol content, a parameter for fungal growth, was continuously enhanced in Sanlim 5-Ho for dark and light incubation periods. However, Sanlim 6-Ho and Nongki 3-Ho recorded the maximized fungal growth under light condition. In fruiting periods the ergosterol contents were lowered in the three strains. Intra- and extracellular enzymes during cultural and fruiting periods were also characterized. The activity of Mn-peroxidase and laccase, which are characteristics enzymes for white rot fungi as lignin degrading enzymes, were determined as a high level overall the periods. As cellulose degrading indicators, the activity of CMCase, avicelase, xylanase and glucanase were detectable in initial incubation period.

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Effects of photoperiod on nutrient digestibility, hair follicle activity and cashmere quality in Inner Mongolia white cashmere goats

  • Zhang, Chong Zhi;Sun, Hai Zhou;Li, Sheng Li;Sang, Dan;Zhang, Chun Hua;Jin, Lu;Antonini, Marco;Zhao, Cun Fa
    • Asian-Australasian Journal of Animal Sciences
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    • v.32 no.4
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    • pp.541-547
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    • 2019
  • Objective: This study investigated the effects of photoperiod on nutrient digestibility, hair follicle (HF) activity and cashmere quality in Inner Mongolia white cashmere goats. Methods: Twenty-four female (non-pregnant) Inner Mongolia white cashmere goats aged 1 to 1.5 years old with similar live weights (mean, $20.36{\pm}2.63kg$) were randomly allocated into two groups: a natural daily photoperiod group (NDPP group:10 to 16 h light, n = 12) and a short daily photoperiod group (SDPP group: 7 h light:17 h dark, n = 12). All the goats were housed in individual pens and fed the same diets from May 15 to October 15, 2015. The digestibility of crude protein (CP), dry matter (DM), and neutral detergent fiber (NDF) were measured in different months, along with secondary hair follicle (SHF) activity, concentration of melatonin (MEL), and cashmere quality. Results: Although there was no significant difference in the live weights of goats between the SDPP and NDPP groups (p>0.05), the CP digestibility of goats in the SDPP group was significantly increased compared to the NDPP group in July, September, and October (p<0.05). For the DM and NDF digestibility of goats, a significant increase (p<0.05) was found during in September in the SDPP group. Furthermore, compared to the NDPP group, the SHF activity in July, the MEL concentration in July, and the cashmere fiber length and fiber weight in October were significantly increased in the SDPP group (p<0.05). Conclusion: The cashmere production of Inner Mongolia white cashmere goats was increased without obvious deleterious effects on the cashmere fibers in the SDPP group (metabolizable energy, 8.34 MJ/kg; CP, 11.16%; short daily photoperiod, 7 h light:17 h dark).

The Hydrogenated Micro-crystalline Silicon(${\mu} c-Si:H$) Films Deposited by Hot Wire CVD Method (Hot Wire CVD법에 의한 수소화된 미세결정 실리콘(${\mu} c-Si:H$) 박막 증착)

  • Lee, Jeong-Cheol;Song, Jin-Su;Park, Lee-Jun
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.37 no.8
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    • pp.17-27
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    • 2000
  • This paper presents deposition and characterization of hydrogenated microcrystalline silicon (${\mu}c$ -Si:H) films on low cost glass substrate by Hot Wire CVD(HWCVD). The HWCVD ${\mu}c$ -Si:H films had deposition rates ranging from 2${\AA}$/sec to 35${\AA}$/sec with the variations of preparation conditions, which was 10 times higher than that of the films obtained from the conventional PECVD method. From the Raman spectroscopy, the prepared silicon films were found to be composed of the mixture of crystalline and amorphous phases. The crystalline volume fraction and average crystallite size, obtained from the Raman To mode peak near 520cm$^{-1}$, were 37-63% and 6-10 nm, respectively. The conductivity activation energy($E_a$) of the ${\mu}c$ -Si:H films, representing the difference of conduction band and Fermi level in an intrinsic semiconductors, increased from 0.22eV to 0.68eV with increasing pressure from 30mTorr to 300mTorr. The increase of $E_a$ with pressure indicates that the deposited films have properties close to intrinsic semiconductors, which is also proved with low dark conductivity of the ${\mu}c$ -Si:H deposited at 300mTorr. The tungsten concentration incorporated into films was about $6{\times}10^{16}atoms/cm^3$ in the samples prepared at wire temperature of 1800$^{\circ}C$.

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Intermediate band solar cells with ZnTe:Cr thin films grown on p-Si substrate by pulsed laser deposition

  • Lee, Kyoung Su;Oh, Gyujin;Kim, Eun Kyu
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.247.1-247.1
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    • 2016
  • Low-cost, high efficiency solar cells are tremendous interests for the realization of a renewable and clean energy source. ZnTe based solar cells have a possibility of high efficiency with formation of an intermediated energy band structure by impurity doping. In this work, ZnO/ZnTe:Cr and ZnO/i-ZnTe structures were fabricated by pulsed laser deposition (PLD) technique. A pulsed (10 Hz) Nd:YAG laser operating at a wavelength of 266 nm was used to produce a plasma plume from an ablated a ZnTe target, whose density of laser energy was 10 J/cm2. The base pressure of the chamber was kept at approximately $4{\times}10-7Torr$. ZnTe:Cr and i-ZnTe thin films with thickness of 210 nm were grown on p-Si substrate, respectively, and then ZnO thin films with thickness of 150 nm were grown on ZnTe:Cr layer under oxygen partial pressure of 3 mTorr. Growth temperature of all the films was set to $250^{\circ}C$. For fabricating ZnO/i-ZnTe and ZnO/ZnTe:Cr solar cells, indium metal and Ti/Au grid patterns were deposited on back and front side of the solar cells by using thermal evaporator, respectively. From the fabricated ZnO/ZnTe:Cr and ZnO/i-ZnTe solar cell, dark currents were measured by using Keithley 2600. Solar cell parameters were obtained under Air Mass 1.5 Global solar simulator with an irradiation intensity of 100 mW/cm2, and then the photoelectric conversion efficiency values of ZnO/ZnTe:Cr and ZnO/i-ZnTe solar cells were measured at 1.5 % and 0.3 %, respectively.

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Temporal Variability of Reduced Sulfur Compounds (RSC) Collected in Tedlar Bag: Simulation of Sample Stability in the Emission Sources (배출원에서의 Tedlar-bag 시료채집법을 이용한 황화합물의 경시적 농도 변화에 대한 연구)

  • Jo, Hyo-Jae;Shon, Zang-Ho;Hong, One-Feel;Kim, Ki-Hyun
    • Journal of Korean Society for Atmospheric Environment
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    • v.27 no.3
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    • pp.281-290
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    • 2011
  • In this study, a series of experiments were carried out to measure temporal stability of reduced sulfur compounds (RSCs) in Tedlar bag samples as a function of elapsed storage time. To this end, temporal variability of 4 RSC standard gases ($H_2S$, $CH_3SH$, DMS, DMDS) was measured up to 29 days. For the purpose of comparison, RSC samples were stored in both individual and mixed state. In the case of mixed standard, samples were also examined to allow comparison between light and dark condition. Then results of $CH_3SH$ data were the most stable with the least change in its concentrations through the end of exps (29 days). When compared with previous studies, the extent of stability appeared to be influenced by the initial concentration levels of samples. When the patterns were compared between individual and mixture samples, differences were not significant in the case of $H_2S$ and DMS. The effects of light conditions on temporal stability were seen to be fairly sensitive on most RSC other than $H_2S$. The results of our study confirm that the stability of RSC storage is affected by their involvement in photochemical reactions.

Measurement of Ballooning Gap Size of Irradiated Fuels Using Neutron Radiography Transfer Method and HV Image Filter

  • Sim, Cheul-Muu;Kim, TaeJoo;Oh, Hwa Suk;Kim, Joon Cheol
    • Journal of the Korean Society for Nondestructive Testing
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    • v.33 no.2
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    • pp.212-218
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    • 2013
  • A transfer method of neutron radiography was developed to measure the size of the end plug and a gap of an intact K102L-2, the irradiated fuel of a ballooned K174L-3, a ballooned and ruptured K98L-3. A typical irradiation time of 25 min. was determined to obtain a film density of between 2 and 3 of SR X-ray film with neutrons of $1.5{\times}10^{11}n{\cdot}cm^{-2}$. To validate and calibrate the results, a RISO fuel standard sample, Cd plate and ASTM-BPI/SI were used. An activated latent image formed in the $100{\mu}m$ Dy foil was subsequently transferred in a dark room for more than 8 hours to the SR film which is a maximum of three half-lives. Due to the L/D ratio an unsharpness of $9.82-14{\mu}m$ and a magnification of 1.0003 were given. After digitizing an image of SR film, the ballooning gap of the plug was discernible by an H/V filter of image processing. The gap size of the ballooned element, K174L-3, is equal to or greater than 1.2 mm. The development of a transfer method played a pivotal role in developing high burn-up of Wolsung and PWR nuclear fuel type.

A study of Hwang Jae Nae Kyung(黃帝內經)'s O Haeng Kui Ryoo(五行歸類) (황제내경(黃帝內徑)의 오행귀류(五行歸類)에 관한 고찰(考察))

  • Kim, Hun Kwan;Hong, Won Sik
    • Journal of Korean Medical classics
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    • v.9
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    • pp.654-699
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    • 1996
  • By studying Hwang Jae Nae Kyung(黃帝內經)'s O Haeng Kui Ryoo(五行歸類) in view of Chinese-Ancient-Thought like Chun In Hap Il Lon(天人合一論). Um Yang O Hang Lon(陰陽五行論). The theory of the month's age the conclusion is reached as follows 1. Chun In Hap Il Lon(天人合一論) means naturally men and nature consist of one energy to counteract each other and then developed to be concidered that the change of men and nature is same one;that is the basic thought of Hwang Jae Nae Kyung(黃帝內經) 2. Um Yang(陰陽) stands originally for the bright and the dark by sunrise or sunset. Ju Yuk Gye Sa Jun(周易繫辭傳) ahs considered Um Yang(陰陽) as the energy to explain changes of nature. O Haeng(五行) meaned originally five necessary materials or stuffs for living and then Chu Yun(鄒衍) has considered the difference between five powers in the nature through the combination with thought of O Haeng(五行). Hwang Jae Nae Kyung(黃帝內經) writes in the viewpoint of Um Yang O Haeng(陰陽五行) to analyze the changes of men and nature effectively. 3. O Haeng Kui Ryoo(五行歸類) is originated from Sang Su Hong Bum(尙書洪範) and its concrete examples are found in Kwan Ja(管子) and Yu SSi Chun Chu(呂氏春秋). O Haeng Kui Ryoo(五行歸類) in Hwang Jae Nae Kyung(黃帝內經) is widly affected by Kwan Ja O Haeng(管子五行) and adopts the opinion of Kum Mun Kyung Hak(今文經學) because of the background of times and medical physiology. 4. Hwang Jae Nae Kyung(黃帝內經) thinks that O Haeng(五行) means Mok(木) is the energy of being born, Hwa(火) growing-up, Kum(金) accumulating, Su(水) concluding, To(土) devoloping. O Haeng Kui Ryoo(五行歸類) in the heaven and the earth is classified by the property of O Haeng(五行). 5. O Haeng Kui Ryoo(五行歸類) in men can be explained so rationally with the property of O Haeng(五行) and the thery of an organism studied.

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Impacts of Different Urban Surfaces on Summer Thermal Performance

  • Jo, Hyun-Kil;Wu, Qian
    • Journal of Environmental Science International
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    • v.24 no.6
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    • pp.819-826
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    • 2015
  • This study measured temperatures and albedos of urban surfaces for different colors and materials during summer, and calculated the energy budget over different urban surfaces to find out the thermal performance affecting the heat built-up. The study selected six surface colors and 13 materials common in urban landscape. Their surface temperatures (Ts) and albedos were measured at a given time interval in the daytime from June to August. Average Ts over summer season for asphalt-colored brick was $4.0^{\circ}C$ higher than that for light red-colored one and $9.7^{\circ}C$ higher than that for white-colored one. The Ts for artificial surface materials of asphalt paving, brown brick wall, and green concrete wall was $6.0^{\circ}C$ higher than that for natural and semi-natural ones of grass, grassy block, and planted concrete wall. There was the greatest difference of $16.3^{\circ}C$ at midafternoon in the Ts between asphalt paving and planted concrete wall. Average albedo over summer season of surface materials ranged from 0.08 for asphalt paving to 0.67 for white concrete wall. This difference in the albedo was associated with a maximum of $15.7^{\circ}C$ difference at midafternoon in the Ts. Increasing the albedo by 0.1 (from 0.22 to 0.32) reduced the Ts by about $1.3^{\circ}C$. Average storage heat at midday by natural and semi-natural surfaces of grass and grassy block was about 10% lower than that by artificial ones of asphalt, light-red brick, and concrete. Reflected radiation, which ultimately contributes to heating the urban atmosphere, was 3.7 times greater for light-red brick and concrete surfaces than for asphalt surface. Thus, surfaces with in-between tone and color are more effective than dark- or white-colored ones, and natural or semi-natural surfaces are much greater than artificial ones in improving the urban thermal environment. This study provides new information on correlation between Ts and air temperature, relationship between albedo and Ts, and the energy budget.