• Title/Summary/Keyword: Ambient gas

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Physico-Chemical Properties of Various Oxide Nanoparticles Synthesized with Electron Beam Irradiation System

  • Sin, Won-Gyu
    • Proceedings of the Korean Vacuum Society Conference
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    • 2014.02a
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    • pp.437-437
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    • 2014
  • Various oxide particles are synthesized in an ambient condition using an electron beam irradiation system. The formation of oxide particles is confirmed by FT-IR spectra results and the X-ray photoelectron spectrum. It is also shown that the morphology and size of oxide particles are significantly influenced by the type and flowrate of dilution gas. The energy dispersive X-ray (EDX) analysis also confirms that various oxide particles are synthesized.

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Major Factors Affecting PM2.5 Water Content in Seoul and Gosan (서울과 고산의 미세입자 수분함량에 영향을 미치는 주요 인자)

  • Choi E. K;Kim Y.P
    • Journal of Korean Society for Atmospheric Environment
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    • v.20 no.6
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    • pp.803-810
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    • 2004
  • Water contents in fine particles at Seoul and Gosan are estimated by using a gas/particle equilibrium model, SCAPE (Simulating Composition of Atmospheric Particles at Equilibrium). Also, sensitivity of particulate inorganic ionic concentrations on the total ionic species is estimated. Water content at Gosan is more sensitive to ambient relative humidity (RH) than Seoul. At both sites water content is most sensitive to sulfate concentration among sulfate, nitrate, and ammonium. Solid salts levels and compositions are also studied.

Speculation of Optical Cavity for Improving Optical Gas Sensor's Characteristics (광학적 가스센서 특성 향상을 위한 광 공동 구조의 고찰)

  • Yi, Seung-Hwan;Park, Jong-Seon
    • Journal of the Korean Institute of Gas
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    • v.12 no.4
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    • pp.63-68
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    • 2008
  • This paper describes about the simulation and the experimental results of optical cavity with curved mirror surface and vertical mirror surface to improve the light intensity and efficiency of the optical sensors. When we use the vertical mirror surface, the distribution of light reached to the filter surface of detector shows an elliptical shape. Whereas, the curved mirror surface focuses the light into circular shape. Therefore, due to focusing effects in case of using curved mirror surface, the light intensity per unit area has been improved. Consequently, the output voltage of gas sensor has been expected to increase. Based upon the simulation, the experiment of gas sensor has been conducted with $CO_2$ gas from 0ppm to 2,500 ppm at 250 ppm step and $25^{\circ}C$, 45%R.H. ambient. The output voltage of gas sensor that has a curved mirror surface increases approximately 200 mV than that of vertical mirror surface.

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Concentration and Gas-particle Partition of PCDDs/Fs and dl-PCBs in the Ambient Air of Ansan Area (안산지역 대기 중 다이옥신 및 dl-PCBs의 오염특성 조사)

  • Heo, Jong-Won;Kim, Dong-Gi;Song, Il-Seok;Lee, Gang-Woong
    • Journal of Korean Society for Atmospheric Environment
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    • v.26 no.5
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    • pp.517-532
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    • 2010
  • After establishment of Banwol industrial complex in 1987, Ansan city becomes the largest industrial sector development in Gyeonggi-do, Korea. As the population and industrial activity grow over this region, toxic air pollutants, particularly POPs (Persistent Organic Pollutants) from various emission sources have been major public concerns. Air samples for POPs monitoring were collected at the industrial sites ($A_2$), residential sites ($B_1$, $B_2$), commercial site (C), and rural/remote site (D) of the area of Ansan during 2008 with a prolonged industrial sampling site $A_1$ from 2001 to 2008. All samples were analysed for 2,3,7,8 substituted-polychlorinated dibenzo-p-dioxin and dibenzofurans (PCDD/Fs) and dioxin like polychlorinatd diphenyls (dl-PCBs). In site $A_1$, a steady decline of their concentrations from 2003 to 2008 was observed due to the reinforced emission guideline from waste incinerators. The average concentration of the PCDD/Fs and dl-PCBs ranged between 0.118 pg-TEQ/$m^3$ (rural/remote site D) and 0.532 pg-TEQ/$m^3$ (industrial area $A_2$). These level were generally consistent with previous studies in Gyeonggi-do, while higher than other places. Most of PCDD/Fs congener were partitioned into particle phase, whereas dl-PCBs were partitioned into gas phase. The logarithm of gas-particle partition coefficient $K_P$ of dl-PCBs and PCDD/Fs were well correlated with sub-cooled liquid vapor pressure $P_L$. The slope $m_T$ of log $K_P$ versus log $P_L$ for PCDD/Fs (-1.22) and dl-PCBs (-1.02) in industrial area ($A_2$) were high compared to other residential/commercial area. It suggests that this area was likely influenced by the direct emission source of PCDD/Fs and dl-PCBs. To simulate the partition of PCDD/Fs and dl-PCBs between gas and particle phase, Junge-Pankow model ($P_L$-base) and $K_{oa}$ model were applied. It was found that J-P model was more suitable than the $K_{oa}$ model in this study.

Vaporization Characteristics of Supercritical Hydrocarbon Fuel Droplet in Convective Nitrogen Environments (유동이 있는 초임계 질소 환경에서 탄화수소 연료 액적의 기화 특성)

  • Lim Jong-Hyuk;Lee Bong-Su;Koo Ja-Ye
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.10
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    • pp.1279-1287
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    • 2004
  • The vaporization characteristics of a liquid heptane droplet in a supercritical nitrogen flow are numerically studied. The transient conservation equations of mass, momentum, energy, and species are expressed in an axisymmetric coordinate system. The governing equations are solved time marching method with preconditioning scheme. The modified Soave-Redlich-Kwong equation of state is employed for taking account of real gas effects such as thermodynamic non-ideality and transport anomaly. Changing the convective velocity and ambient pressure, several parametric studies are conducted. The numerical results show that the two parameters, Reynolds number and dimensionless combined parameter(${\mu}$s/${\mu}$d)(equation omitted), have influence on supercritical droplet vaporization.

Characteristics of Contact resistivity on RTP annealing temperature and time after Plasma ion implant (플라즈마 이온주입 후 RTP 열처리 온도와 시간에 따른 접촉저항 특성)

  • Choi, Jang-Hun;Do, Seung-Woo;Lee, Yong-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.06a
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    • pp.5-6
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    • 2009
  • In this paper, plasma ion implant is performed with $PH_3$ gas diluted by helium gas on P-type Si wafer (100). Spike Rapid Thermal Processing(RTP) annealing performed for 30~60 sec from $800\;^{\circ}C$ to $1000\;^{\circ}C$ in $N_2+O_2$ ambient. Crystalline defect is analyzed by Transmission Electron Microscope(TEM) and Double crystal X-ray Diffraction(DXRD). Contact resistivity($\rho c$), contact resistance(Rc) and sheet resistance(Rs) are analyzed by measuring Transfer Length Method(TLM) using 4155C analysis. As annealing temperature increase, Rs decrease and ${\rho}c$ and Rc increase at temperature higher than $850\;^{\circ}C$. We achieve low Rs, ${\rho}c$ and Rc with Plasma ion implant and spike RTP.

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Gas Chromstographic Analysis of Hydrocarbons in Atmospheric Air around Odae and Ocheon Area (울산군 오대오천부락 근처의 대기 중 탄화수소성분의 가스크로마토그래피에 의한 분석)

  • 양성봉;김영태
    • Journal of Environmental Science International
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    • v.3 no.4
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    • pp.373-380
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    • 1994
  • Volatile organic compounds in the ambient air were gathered irregularly by normal temperature concentrating method at Odea-ri and Oceon-ri Ulsan-gun in the neighbourhood of Ulsan Petrochemical Industrial Complex and analyzed with gas chromatograph. Several hydrocarbons in common aklospheric air or emitted fugitively from the chemical plants were identified and quantified by comparison with the retention times of standard compounds. The results from several field surveys in 1992 show that the concentrations of styrene at residential area of Odea-ri and Ocheon-ri were less than 0.4 ppm, but once a while greater within the chemical plants area. When it smelled unpleasantly in these area, the concentration of hydrocarbons were also high. It was concluded that the close and long-term investigation about other odorous components but hydrocarbons will be necessary to ascertain the cause of unpleasant odor of these area.

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Theoretical and Numerical Study on Scavenge Characteristics from a prechamber for use in an engine (엔진 예혼합실의 소기 특성에 대한 이론 및 수치해석적 연구)

  • Heo, Hyeung-Seok;Suh, Yong-Kweon
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1401-1406
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    • 2004
  • In this paper, we present the theoretical and numerical results of scavenge characteristics in a small prechamber of an HCCI(Homogeneous Charge Compression Ignition) engine. Two theoretical models are proposed in prediction of the scavenge time and the efficiency ; one is the non-mixing models in which it is assumed that the input gas($CH_{4}$) and the existing gas(air) do not mix with each other, and the other is the fully-mixed model in which the two gases are assumed to mix completely before ejecting to the ambient air. Focus is also given to the effect on the scavenge performance of the size of the chamber oulet.

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An Analysis on the Discharge Characteristics through 1-D Numerical Simulation in an AC PDP (AC PDP에서 1차원 수치해석을 통한 방전 특성 연구)

  • Lee, J.H.;Seo, J.H.;Lee, S.H.
    • Proceedings of the KIEE Conference
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    • 2003.10a
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    • pp.220-222
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    • 2003
  • In this paper, we analyze on the discharge characteristics through 1-D simulations in an at plasma display panel discharge cell. The model is based on a Poisson' equation, continuity and drift-diffusion equation. Results are presented in a 95% neon, 5% xenon gas mixture, for a gap length of 100us and a gas pressure of 400Torr at ambient temperature. Results for other gap length are also discussed. As a result, an increase of the gap cause increase of luminous efficiency but with larger sustaining voltage.

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High-Pressure Droplet Vaporization with Emphasis on the Vapor-Liquid Equilibrium Calculation (플래쉬 상평형 계산에 의한 고압 액적기화의 수치적 연구)

  • Lee, Kang-Won;Chae, Jong-Won;Yoon, Woong-Sup
    • 한국연소학회:학술대회논문집
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    • 2001.06a
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    • pp.106-118
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    • 2001
  • A rigorous study of single droplet vaporization under quiescent high pressure atmosphere is attempted adopting method of flash evaporation calculation for vapor-liquid equilibrium. Results due to flash method shows excellent agreement with measurement. Also shown is the present model fairly capable of depicting transients of droplet vaporization under high pressure environment, such as ambient gas solubility, property variation, and multicomponent transports. Systematic treatment of these effects with emphasis on vapor-liquid phase equilibrium revealed; conventional treatment for subcritical droplet vaporization, such as $d^2$-law, leads to erroneous prediction of droplet history, augmented gas solubility is significant under supercritical pressure, and vaporization rate proportionally increase with pressure.

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