• Title/Summary/Keyword: OAK

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Investigation of Nanoparticle Generation during Surface Decontamination by Low-Energy-Fluence Laser Ablation (저에너지 플루언스(fluence) 레이저 어블레이션(ablation)을 통한 표면오염제거과정에서의 나노입자의 생성에 관한 연구)

  • Lee, Doh-Won;Cheng, Meng-Dawn
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2003.11a
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    • pp.199-199
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    • 2003
  • During the cleanup of US Department of energy facilities, contaminated materials, toxic and hazardous radionuclides (e.g., Th, Cs, and U) and heavy metals (e.g., Cr, Hg, Pb, and Ni)-laden ultrafine particles are generated. The size of the particles is up to about 200 nm. Understanding of the production of these nanometer size particles is critical in determining the surface cleaning efficiently. (omitted)

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Ex-situ Catalytic Pyrolysis of Korean Native Oak Tree over Microporous Zeolites (미세기공 제올라이트를 이용한 국내 수종 굴참나무의 간접 촉매 열분해)

  • Kim, Young-Min;Kim, Beom-Sik;Chea, Kwang-Seok;Jo, Tae Su;Kim, Seungdo;Park, Young-Kwon
    • Applied Chemistry for Engineering
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    • v.27 no.4
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    • pp.407-414
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    • 2016
  • Ex-situ catalytic pyrolysis of a Korean native oak tree over microporous zeolites (HZSM-5, HBeta, and HY) was performed by using a fixed bed reactor. The effect of sample to catalyst ratio and reaction temperature was also investigated to optimize production conditions of high quality bio-oil. Among three catalysts, HZSM-5 showed the highest aromatic formation due to its proper pore size and strong acidity. Although HY and HBeta also showed the catalytic activity, they produced larger amounts of coke due to their larger pore size. The smaller ratio of the sample to the catalyst and higher reaction temperature were also required to maximize the yields of aromatic hydrocarbons via the catalytic pyrolysis of oak tree over HZSM-5.

Stomatal Control and Strategy Segregation to Drought Stress in Young Trees of Several Oak Species (수종 참나무속 유식물의 건조스트레스에 대한 기공저항의 조절과 전략의 분화)

  • 김종욱;김준호
    • The Korean Journal of Ecology
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    • v.17 no.3
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    • pp.241-249
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    • 1994
  • Leaf diffusive resistance (LDR), stomatal density, length of guard cell and hair density of leaves of 6 oak species were determined under withdrawal of water, and their strategies of drought stress were analyzed by principal component analysis. LDR of Quercus acutissima, Q. aliena and Q. serrata increased earlier than those of the other species at high leaf water potential $({\Psi}_{leaf})$ or low water saturation deficit (WSD), which was an avoidance mechanism reducing damage by water stress. Q. variabilis with low stomatal density, small stomatal size and high hair density had avoidance mechanisms increasing LDR at high $({\Psi}_{leaf})$ However, Q. mongolica and Q. dentata increased LDR at low $({\Psi}_{leaf})$ as xeric species do. Results from principal component analysis on the 15 variables related to strategies of drought stress indicated that the 6 oak species were divided into 2 groups: (1) Q. acutissima, Q. aliena and Q. serrata as mesic habitat species and (2) Q. variabilis, Q. mongolica and Q. dentata as xeric habitat species. Among three xeric species Q. acutissima differed from the other two species in the drought strategies such as high hair density, low stornatal density, high leaf area ratio, stomatal closing at low $({\Psi}_{leaf})$ and small cell wall elasticity. The results could reasonably explain their drought strategies in natural habitat.

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Relationship between Pollen Concentration and Meteorological Condition in an Urban Area (도시지역 공중화분 농도와 기상조건과의 관계)

  • Oh, In-Bo;Kim, Yangho;Choi, Kee-Ryong;Lee, Ji Ho
    • Journal of Korean Society for Atmospheric Environment
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    • v.29 no.6
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    • pp.780-788
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    • 2013
  • This study attempted to determine important meteorological parameters related to airborne pollen concentrations in urban areas. Hourly pollen measurement data were prepared from a regular sampling with a volumetric Burkard spore trap at a site in the Ulsan city, during the spring season (March~May) of 2011. Results showed that the daily mean and maximum concentrations for total pollen counts during the spring season were statistically significantly correlated with both air temperature and wind speed; daily mean pollen concentration was the most highly related to daily maximum temperature (r=0.567, p<0.001). It was also identified that pollen concentration has a stronger relationship with wind speed at the rural site than at the urban one, which confirms that strong wind conditions over the pollen sources area can be favorable for pollen dispersal, resulting in increases in airborne pollen concentrations downwind. From the results of an oak-pollen episode analysis, it was found that there was a significant relationship between hourly variation of oak pollen concentrations and dynamic meteorological factors, such as wind and mixing height (representing the boundary layer depth); especially, a strong southwestern wind and elevated mixing height was associated with high nocturnal concentrations of oak pollen. This study suggests that temperature, wind, and mixing height can be important considerations in explaining the pollen concentration variations. Additional examination of complex interactions of multiple meteorological parameters affecting pollen behavior should be carried out in order to better understand and predict the temporal and spatial pollen distribution in urban areas.

Real-time Implementation of a GSM-EFR Speech Coder on a 16 Bit Fixed-point DSP (16 비트 고정 소수점 DSP를 이용한 GSM-EFR 음성 부호화기의 실시간 구현)

  • 최민석;변경진;김경수
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.7
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    • pp.42-47
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    • 2000
  • This paper describes a real-time implementation of a GSM-EFR (Global System for Mobil communications Enhanced Full Rate) speech coder using OakDSP core; a 16bit fixed-point Digital Signal Processor (DSP) by DSP Group, Inc. The real-time implemented speech coder required about 24MIPS for computation and 7.06K words and 12.19K words for code and data memory, respectively. The implemented GSM-EFR speech coder passes all of test vectors provided by ETSI (European Telecommunication Standard Institute), and perceptual speech quality measurement using MNB algorithm shows that the quality of the GSM-EFR speech coder is similar to the one of 32kbps ADPCM. The real-time implemented GSM-EFR speech coder which is the highest bit-rate mode of the GSM-AMR speech coder will be used as the basic structure of the GSM-AMR speech coder which is embedded in MODEM ASIC of IMT2000 asynchronous mode mobile station.

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