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Searching for cosmic missing baryons with DIOS - Diffuse Intergalactic Oxygen Surveyor -
Yasushi Suto,Akihiro Furuzawa,Kazuhisa Mitsuda,Manabu Ishida,Noriko Y. Yamasaki,Ryuichi Fujimoto,Shin Sasaki,Tae Furusho,Takaya Ohashi,Yoshitaka Ishisaki,Yuzuru Tawara 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.1
Approximately 30 to 50 percent of the total baryons in the present universe is supposed to take the form of wa arm/hot intergalactic medium (WHIM) whose X-ray continuum emission is very weak. In order to carry out a direct and homogeneous survey of elusive cosmic missing baryons, we propose a dedicated soft-X-ray mission, DIOS (Diffuse Intergalactic Oxygen Surveyor). The unprecedented energy resolution ( 2eV) of the XSA (X-ray Spectrometer Array) on-board DIOS enables us to identify WHIM with gas temperatures T = 106က7K and overdensity = 10က100 located at z < 0:3 through emission lines of Ovii and Oviii. DIOS, which will hopefully be launched in several years time, promises to open a new window of detection and characterization of cosmic missing baryons and to provide yet another important and complementary tool to trace the large-scale structure of the universe.
Reduction of acetaldehyde formation from pulverized solid woods by thermal and chemical treatments
Mizukoshi, Atsushi,Kurosaki, Yosuke,Yamamoto, Naomichi,Noguchi, Miyuki,Iizuka, Atsushi,Yamasaki, Akihiro,Yanagisawa, Yukio Springer-Verlag 2018 Wood science and technology Vol.52 No.2
<P>High concentrations of acetaldehyde are often observed in indoor environments. One possible source of this is acetaldehyde formation produced by ethanol from wood building materials. To characterize indoor acetaldehyde formation and propose methods for its reduction, chamber-based experiments were conducted in which alcohols were added to pulverized solid woods. The results indicated that acetaldehyde was generated from the ethanol-added wood materials, and softwoods, namely Japanese cedar, Japanese cypress, and Swedish redwood generated more acetaldehyde than the other three woods. The experiments using different types of alcohols of methanol, ethanol, 1-propanol, and 2-propanol revealed a tendency similar to the reported enzymatic profile of the higher plant-derived alcohol dehydrogenase. It was confirmed that acetaldehyde generation was reduced by treatment methods typically used for inactivating enzymes, namely chemical treatments using pyrazole, borate, and urea and thermal treatments. The findings suggest that the chemical and thermal treatment methods are useful to reduce acetaldehyde generation in indoor environments.</P>
TRACING BRIGHT AND DARK SIDES OF THE UNIVERSE WITH X-RAY OBSERVATIONS
SUTO YASUSHI,YOSHIKAWA KOHJI,DOLAG KLAUS,SASAKI SHIN,YAMASAKI NORIKO Y.,OHASHI TAKAYA,MITSUDA KAZUHISA,TAWARA YUZURU,FUJIMOTO RYUICHI,FURUSHO TAE,FURUZAWA AKIHIRO,ISHIDA MANABU,ISHISAKI YOSHITAKA The Korean Astronomical Society 2004 Journal of The Korean Astronomical Society Vol.37 No.5
X-ray observations of galaxy clusters have played an important role in cosmology, especially in determining the cosmological density parameter and the fluctuation amplitude. While they represent the bright side of the universe together with the other probes including the cosmic microwave background and the Type Ia supernovae, the resulting information clearly indicates that the universe is dominated by dark components. Even most of cosmic baryons turns out to be dark. In order to elucidate the nature of dark baryons, we propose a dedicated soft-X-ray mission, DIOS (Diffuse Intergalactic Oxygen Surveyor). Recent numerical simulations suggest that approximately 30 to 50 percent of total baryons at z = 0 take the form of the warm-hot intergalactic medium (WHIM) with $10^5K < T < 10^7K $which has evaded the direct detection so far. The unprecedented energy resolution (${\~} 2eV$) of the XSA (X-ray Spectrometer Array) on-board DIGS enables us to identify WHIM with gas temperature $T = 10^6 {\~} 10^7K$ and overdensity $\delta$ = 10 ${\~}$ 100 located at z < 0.3 through emission lines of OVII and OVIII. In addition, WHIMs surrounding nearby clusters are detectable with a typical exposure time of a day, and thus constitute realistic and promising targets for DIOS.
Sang Jun Yoon,Jae Goo Lee,Hideo Tajima,Akihiro Yamasaki,Tetsuya Nakazato,Hiroaki Tao,Fumio Kiyono 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.3
Extractions of five kinds of lanthanide metal ions by bis(2-ethylhexyl)phosphoric acid (DEHPA) with [1-Cn-3-methylimidazolium][PF6](Cn = C2, C4) or [1-butyl-4-methylpyridinium][PF6] were carried out under various DEHPA and HNO3 concentrations from 0 to 1 M and under different temperature conditions from 298 to 333 K. These results were compared with those using the conventional organic solvent, hexane, in terms of their distribution coefficient values. Under all of the conditions in this study,the ionic liquid system shows more than three times greater extractability for lanthanide compared to when hexane was used. The distribution coefficient of lanthanide ions decreased as the length of the alkyl chain increased from the ethyl to the butyl. In addition, the imidazolium cation generally shows a higher distribution coefficient compared to the pyridinium cation in an ionic liquid. The concentration ratio of lanthanides and DEHPA resulted in an extraction affinity transition for lanthanides. Also evaluated in this study were issues related to the selectivity associated with the lanthanide mixture and the dependency of the ionic radius during lanthanide extraction. 2010 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
수소불화탄소를 포함하는 혼합기체의 가스 하이드레이트 상평형
서용원(Seo, Yong-Won),이승민(Lee, Seung-Min),이주동(Lee, Ju-Dong),이강우(Lee, Gang-Woo),야카사키아키히로(Yamasaki, Akihiro),키요노후미오(Kiyono, Fumio) 한국신재생에너지학회 2007 한국신재생에너지학회 학술대회논문집 Vol.2007 No.11
(HFC(hydrofluorocarbon, 수소불화탄소)는 오존층 파괴 지수가 낮기 때문에 CFC(chlorofluorocarbon)의 대체 물질로 냉매와 발포제로 널리 사용되고 있는 물질이다. 하지만 HFC는 지구온난화 지수가 높은 기체이므로 대기중으로 방출되는 것을 막기 위해 분리/회수하여 재활용하는 것이 중요하다. 본 연구에서는 공기와 HFC의 혼합기체로부터 HFC만을 분리해 내는 방법으로 가스 하이드레이트 형성법을 제안하였다. 이 방법의 열역학적 타당성을 검증하기 위하여 질소+HFC-134a 혼합기체에 대하여 275-285 K의 온도 범위와 1-27 bar의 압력범위에 걸쳐서 가스 하이드레이트 상평형을 측정하였다. 질소는 가스 하이드레이트를 형성하기 위하여 0 ?C에서 150 bar 이상의 높은 압력이 필요한 반면 HFC-134a는 대기압에 가까운 낮은 압력이 필요하다. 두 기체의 평형 압력의 차가 크다는 것은 가스 하이드레이트 형성법을 이용할 경우 기체의 분리 효율이 매우 높다는 것을 나타낸다. 그리고, 본 실험을 통해서 얻어진 혼합기체의 하이드레이트상(H)-액상(L_W)-기상(V)의 3상 평형선이 순수한 HFC-134a의 3상 평형선에 가깝게 위치하였다. 이는 가스 하이드레이트를 이용한 분리법이 낮은 압력에서 운전될 수 있음을 나타낸다. 이 분리법은 낮은 압력에서 운전되어 경제적일 뿐만 아니라 물 이외의 다른 매개체를 사용하지 않기 때문에 환경 친화적인 공정이라 할 수 있다.