• Title/Summary/Keyword: Dry ice

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Rapid Climate Change During the Deglaciation of Lake Hovsgol, Mongolia

  • Chun, Jong-Hwa;Cheong, Dae-Kyo
    • The Korean Journal of Quaternary Research
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    • v.19 no.2
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    • pp.55-58
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    • 2005
  • A 120-cm core recovered from Lake Hovsgol, the northern Mongolia provides evidence for climate variability since the Marine Isotope Stage 3, representing a sharp lithological change. The lowermost part of the core consists of diatom-barren calcareous silty clay without coarse sands, framboidal pyrite, and biogenic components deposited during the MIS 3. Following the last glacial maximum, in-situ moss is included in the sediments, as lake-level was retreated by cold and dry environment with low precipitation. The AMS radiocarbon ages of the plant fragments match a marked lithologic boundary between 14,060 and 14,325 $^{14}C$ yr BP. The contents of coarse sands abruptly increase, indicating probably wind-derived sandy dust or coarse grains contributed from floating icebergs. And abundant framboidal pyrite grains were deposited in an anoxic environment, as reflected by high accumulation of organic matters at a low lake stand. During the deglaciation, quantities of coarse sands, ostracod, shell fragments, framboidal pyrite, and diatom markedly varies by regional and global scale climate regimes. Some allochthonous coarse sands were probably ice-rafted debris derived from floating icebergs. A rapid increase in diatom productivity probably marked the onset of Bolling-Allerod warming. Subsequent high concentration of framboidal pyrite probably represents a dry and cold condition, such as Younger Drays events. Consistent warm period with high precipitation at Holocene is documented by diatomaceous clayey ooze without framboidal pyrite, coarse sands, and ostracod.

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Rapid climate change during the deglaciation of Lake Hovsgol, Mongolia

  • Chun, Jong-Hwa;Cheong, Dae-Kyo
    • Proceedings of the Korean Quaternary Association Conference
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    • 2005.10a
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    • pp.34-39
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    • 2005
  • A 120-cm core recovered from Lake Hovsgol, the northern Mongolia provides evidence for climate variability since the Marine Isotope Stage 3, representing a sharp lithological change. The lowermost part of the core consists of diatom-barren calcareous silty clay without coarse sands, framboidal pyrite, and biogenic components deposited during the MIS 3. Following the last glacial maximum, in-situ moss is included in the sediments, as lake-level was retreated by cold and dry environment with low precipitation. The AMS radiocarbon ages of the plant fragments match a marked lithologic boundary between 14,060 and 14,325 $^{14}C$ yr BP. The contents of coarse sands abruptly increase, indicating probably wind-derived sandy dust or coarse grains contributed from floating icebergs. And abundant framboidal pyrite grains were deposited in an anoxic environment, as reflected by high accumulation of organic matters at a low lake stand. During the deglaciation, quantities of coarse sands, ostracod, shell fragments, framboidal pyrite, and diatom markedly varies by regional and global scale climate regimes. Some allochthonous coarse sands were probably ice-rafted debris derived from floating icebergs. A rapid increase in diatom productivity probably marked the onset of Bolling-Allerodwarming. Subsequent high concentration of framboidal pyrite probably represents a dry and cold condition, such as Younger Drays events. Consistent warm period with high precipitation at Holocene is documented by diatomaceous clayey ooze without framboidal pyrite, coarse sands, and ostracod.

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Remotely Operated Decontamination Systems for Use in DFDF

  • Kim, Kiho;Park, Jangjin;Myungseung Yang
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2003.11a
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    • pp.438-446
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    • 2003
  • This paper presents the development of the remotely operated decontamination systems for use in a highly radioactive zone of the DUPIC Fuel Development facility of the Irradiated Material Examination Facility at the Korea Atomic Energy Research Institute. The remotely operated decontamination systems were designed to completely eliminate human interaction with hazardous radioactive contaminants. These decontamination systems are mainly classified into three systems depending on the task environment - a fabrication equipment decontamination system, a hot-cell floor decontamination system, and an isolation room floor decontamination system. A decontamination system for contaminated fabrication equipment utilizes dry ice pellet blasting method to decontaminate contaminated surface of the equipment. The decontamination systems for the hot-cell floor and isolation room floor employ a vacuum cleaning method to decontaminate the contaminated floor and collect loose dry spent nuclear fuel debris and other radioactive waste placed on the floor. The human operator from the out-of-cell performs a series of decontamination tasks remotely by manipulating decontamination systems located in-cell via a handcontroller with the aid of vision feedback information. The environmental, functional and mechanical design considerations, control system and capabilities of the remotely operated decontamination systems at a high radioactive environment are also described.

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Purification of the Vacuolar Arginine Transporter from Neurospora crassa (Neurospora crassa로부터 arginine transporter의 순수분리)

  • ;Weiss, R. L.
    • Korean Journal of Microbiology
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    • v.27 no.2
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    • pp.117-123
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    • 1989
  • Radioactive N-$\alpha$-p-nitrobenzoxycarbonyl (NBZ)-L-[2,$3-^{3}$H] arginyl diazomethane was used as an affinity label for the vacuolar arginine transporter in Neurospora crassa. Vacuolar matrix proteins were removed by fracturing the membranes with freeze-thaw method in dry ice/ethanol bath. Vacuolar membrane proteins were then wasged with 500mM NaCl to remove ionically bound derivatives and peripheral membrane proteins from vacuolar membranes. After dissolved in 1% Titon X-100, dissolved vacuolar memvrane proteins were separated with molecular sieve column chromatography, anion and cation exchange chromatographies. The arginine transporter was purified giving the purification factor of 1136.

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CO2 dry-ice cleaning for the removal of air preheater plugging in coal-fired power plant. (석탄 화력발전소의 공기예열기 막힘 제거를 위한 CO2 드라이아이스 세정)

  • Ju, Saerom;Kim, Gyeong-Min;Kim, Do-Jung;Kim, Dong-Won
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2014.11a
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    • pp.204-206
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    • 2014
  • 석탄 화력발전소에는 연소가스의 질소산화물(NOx) 저감을 위한 SCR(selective catalytic reduction)설비가 운전되고 있으며, SCR은 환원제인 암모니아($NH_3$)를 이용하여 연소가스 내에 질소산화물을 물과 질소로 분해하는 역할을 한다. 그러나, 연소가스 중의 일부 삼산화황($SO_3$)과 미반응 암모니아가 결합하여 황산암모늄염(Ammonium bisulfate; $NH_4HSO_4$)을 생성하며, 이는 후단 APH(air preheater)의 열소자에 점착된 후 분진들과 함께 성장하여 막힘을 야기한다. 막힘이 발생된 APH는 연소가스의 흐름을 방해하기 때문에 차압을 증가시키며, 이는 발전효율의 감소뿐만 아니라 급전정지를 초래한다. 이를 해결하기 위하여 $CO_2$ 드라이아이스 세정 방법을 적용하였으며, pilot-scale plant에서 실험을 수행하였다. 또한, 드라이아이스 공정변수인 분사압력과 분사시간을 제어하여 pilot-scale plant의 APH 열소자 표면에 생성되어있는 오염물질들의 제거효율을 관찰한 결과 95 %의 높은 제거효율을 보였다.

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A Development of The Road Surface Decision Algorithm Using SVM(Support Vector Machine) Clustering Methods (SVM(Support Vector Machine) 기법을 활용한 노면상태 판별 알고리즘 개발)

  • Kim, Jong Hoon;Won, Jae Moo
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.12 no.5
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    • pp.1-12
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    • 2013
  • Road's accidents caused by Ice, snow, Wet of roads surface conditions and weather conditions situations that are constantly occurring. That is, driver's negligence and safe driving ability of individuals due to lack of awareness, and Road management main agent(the government and the public, etc.) due to road conditions, if there is insufficient information. So Related research needs is a trend that is required. In this study, gather Camera(Stereo camera)'s image data, and analysis polarization coefficients and wavelet transform. And unlike traditional single-dimensional classification algorithms as multi-dimensional analysis by using SVM classification techniques, develop an algorithm to determine road conditions. Four on the road conditions (dry, wet, snow, ice) recognition success rate for the detection and analysis of experiments.

The Lichen Flora of Oases of Continental Antarctic, and the Ecological Adaptations of Antarctic Lichens

  • Andreev, Mikhail
    • 한국균학회소식:학술대회논문집
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    • 2006.10a
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    • pp.24-28
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    • 2006
  • Author have studies lichen flora of the most important ice-free areas of Continental Antarctic: Bunger Hills, and the vicinity of Prudz Bay (Larsemann Hills, and Radok Lake in Prince Charles Mountains). Totally 44 lichen species from 22 genera were reported for Bunger Hills and 50 lichen species from 22 genera and 10 families: Acarosporaceae, Lecanoraceae, Lecideaceae, Parmeliaceae, Pertusariaceae, Physciaceae, Rhizocarpaceae, Stereocaulaceae, Theloschistaceae, and Umbilicariaceaewere reported for the Prudz Bay Region. 20 lichen species were found in the region for the first time. Phytogeographic analysis indicated a relatively high proportion of species with bipolar distribution - about 50% of recorded lichen species. About 30% of lichens normally don't extend into maritime zone occurring in continental Antarctic only. The most common lichen families in the region are Buelliaceae, Lecanoraceae and Teloschistaceae. The water supply and not a temperature is the critical factor for lichens in the Continental Antarctic. Moisture appears to be supplied for lichens not only from snow-melt water but mainly from air. In Maritime Antarctic, due to high air humidity macrolichens form communities everywhere (Himantormia, Usnea and Umbilicaria). In oases of Continental Antarctic extensive sites are lacking in lichen cover, even if the ground is normally snow free. Lichens occur at humid sites with moisture which were brought by winds over the ice cap and poorly developed or absent in dry areas. Of particular significance for lichens are substrate characteristics, animals influence and salinity brought by wind in coastal areas. Most rich lichen vegetation developed in oases around nests of snow petrels, where the melt water is enriched by nutrients. In contrast, the most pure vegetation is on mobile sand and gravel and in salted coastal habitats.

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Oxidative Cleavage Products of ${\zeta}-Carotene$ (${\zeta}-Carotene$의 산화개열산물)

  • Kim, Seon-Jae
    • Korean Journal of Food Science and Technology
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    • v.32 no.5
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    • pp.985-990
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    • 2000
  • ${\zeta}-Carotene$ was subjected to ozonolysis in ice-cold dichloromethane. The ozonolysis products were fractionated with a silica column and the carbonyl fraction was analyzed by ODS-HPLC with a photodiode array detector. ${\zeta}-Carotene$ was solubilized in toluene, and then oxidized by incubating at $37^{\circ}C$, 72 hr under atmospheric oxygen. Carbonyl compound and acidic compound were produced. In comparison with autoxidation and ozonolysis, each compound showed the same retention time and UV-vis spectra were identical to the reference cleavage products prepared by ozonolysis of ${\zeta}-carotene$. Absorption spectrum of acidic compound was similar to that of standard 4,5-didehydrogeranyl geranyl acid which is known to possess biological activity. Thus, eccentric cleavage of ${\zeta}-carotene$ was confirmed to occur in vitro under oxidation condition.

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Comparison of Enhancement Effect of Ninhydrin Fluorescent Fingerprints Using Zinc Chloride and Liquid Nitrogen and Introducing the New Cooling Method for Post Treatment of Ninhydrin (염화아연(Zinc Chloride)과 액화질소를 사용한 닌히드린(Ninhydrin) 형광지문의 증강 효과 비교 및 실무적 사용을 위한 새로운 냉각방법에 관한 연구)

  • Jeon, Su-Yeon;Kim, Chang-Yong;Kim, Mi-So;Yu, Je-Seol
    • Journal of the Korea Convergence Society
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    • v.11 no.6
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    • pp.75-82
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    • 2020
  • We identify the enhancement effects of zinc chloride and liquid nitrogen on low quality ninhydrin-developed fingerprint and we wanted to find out another cooling methods available for ninhydrin/Zn fingerprint enhancement besides the liquid nitrogen, which is hard to access. Artificial sweat was used to make the same level of fingerprints, and fingerprints developed by each technique were evaluated by SWGFAST standard and compared the average score and standard deviation. As a result of the experiment, ninhydrin/Zn-liquid nitrogen got 3.2 and 3.3 as average scores that enough to identify an individual such as 1,2-IND/Zn or DFO. Also, experiments using dry ice instead of liquid nitrogen as a way of the ninhydrin/Zn-developed fingerprints enhancement resulted in 3.0 and 2.9 as average scores, therefore, it was confirmed that dry ice is also a sufficient cooling method to be considered in practice in the field of forensic science.