• 제목/요약/키워드: secondary emission

검색결과 399건 처리시간 0.027초

대기 정체와 수용성 에어로졸 입자의 질량크기분포의 관계 (Effect of Air Stagnation Conditions on Mass Size Distributions of Water-soluble Aerosol Particles)

  • 박승식;유근혜
    • 한국대기환경학회지
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    • 제34권3호
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    • pp.418-429
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    • 2018
  • Measurements of 24-hr size-segregated ambient particles were made at an urban site of Gwangju under high pressure conditions occurred in the Korean Peninsula late in March 2018. The aim of this study was to understand the effect of air stagnation on mass size distributions and formation pathways of water-soluble organic and inorganic components. During the study period, the $NO_3{^-}$, $SO_4{^{2-}}$, $NH_4{^+}$, water-soluble organic carbon (WSOC), and humic-like substances(HULIS) exhibited mostly bi-modal size distributions peaking at 1.0 and $6.2{\mu}m$, with predominant droplet modes. In particular, outstanding droplet mode size distributions were observed on March 25 when a severe haze occurred due to stable air conditions and long range transport of aerosol particles from northeastern regions of China. Air stagnation conditions and high relative humidity during the study period resulted in accumulation of primary aerosol particles from local emission sources and enhanced formation of secondary ionic and organic aerosols through aqueous-phase oxidations of $SO_2$, $NO_2$, $NH_3$, and volatile organic compounds, leading to their dominant droplet mode size distributions at particle size of $1.0{\mu}m$. From the size distribution of $K^+$ in accumulation mode, it can be inferred that in addition to the secondary organic aerosol formations, accumulation mode WSOC and HULIS could be partly attributed to biomass burning emissions.

Numerical Study on the Impact of Power Plants on Primary PM10 Concentrations in South Korea

  • Park, Il-Soo;Song, Chang-Keun;Park, Moon-Soo;Kim, Byung-Gon;Jang, Yu-Woon;Ha, Sang-Sub;Jang, Su-Hwan;Chung, Kyung-Won;Lee, Hyo-Jung;Lee, Uh-Jeong;Kim, Sang-Kyun;Kim, Cheol-Hee
    • Asian Journal of Atmospheric Environment
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    • 제12권3호
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    • pp.255-273
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    • 2018
  • To develop effective emission abatement strategies for eighteen coal-fired power plants located throughout Korea, power plant emission data and TAPM (The Air Pollution Model) were used to quantify the impact of emission reductions on primary $PM_{10}$ concentrations. TAPM was validated for two separate time periods: a high $PM_{10}$ concentration period from April 7 to 12, 2016, and a low $PM_{10}$ concentration period from June 1 to June 6 2016. The validated model was then used to analyze the impacts of five applicable power plant shut-down scenarios. The results showed that shut-down of four power plants located within the Seoul metropolitan area (SMA) would result in up to 18.9% reduction in maximum $PM_{10}$ concentrations, depending on synoptic conditions. A scenario for the shutdown of a single low stack height with highest-emission power plant located nearest to Seoul showed a small impact on averaged $PM_{10}$ concentrations (~1%) and 4.4% ($0.54{\mu}g/m^3$) decrease in maximum concentration. The scenario for four shutdowns for power plants aged more than 30 years within SMA also showed a highest improvement of 6.4% ($0.26{\mu}g/m^3$ in April) in averaged $PM_{10}$ concentrations, and of 18.9% ($2.33{\mu}g/m^3$ in June) in maximum concentration, showing almost linear relationship in and around SMA. Reducing gaseous air pollutant emissions was also found to be significant in controlling high $PM_{10}$ concentrations, indicating the effectiveness of coreduction of power plant emissions together with diesel vehicle emissions in the SMA. In addition, this study is implying that secondary production process generating $PM_{10}$ pollution may be a significant process throughout most regions in Korea, and therefore concurrent abatement of both gas and particle emissions will result in more pronounced improvements in air quality over the urban cities in South Korea.

Analysis of Auxiliary Device in a Gas-solid Cyclone by Experimental and Computational Approaches

  • Lee, Ju-Yeol;Park, Duck-Shin;Jo, Young-Min
    • Journal of Korean Society for Atmospheric Environment
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    • 제19권E1호
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    • pp.21-28
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    • 2003
  • An auxiliary device, called Post Cyclone (PoC). had been introduced and primarily examined in earlier works which proved the reduction of the emission of fine dust from the gas-solid cyclones without incurring significant increase of cost and pressure drop. It has been known that the PoC has some advantages over other secondary dust treatment devices such as (a) simple design, (b) low cost of manufacture, (c) minimum additional pressure drop, (d) high recoverbility of the product dust, and (e) simplicity of operation. Despite the potential advantage, however, lack of practical data confined its plausible application in wide areas. Thus, in this work, a few serial experiments were conducted in terms of a few operation conditions, and the particle trajectories throughout the cyclone set-up were visually analyzed by using a commercial computer simulation program (FLUENT).

지향성 에너지를 이용한 고고도 장기체공 태양광 무인항공기 운용 개념 연구 (A Study on Operational Concept of Solar Powered HALE UAV Using Directed-Energy)

  • 안효정
    • 신재생에너지
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    • 제7권3호
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    • pp.59-66
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    • 2011
  • Recently, an UAV using green energy for propulsion has been developed due to exhaustion of fossil fuel. This aircraft runs on electric motors rather than internal combustion engines, with electricity coming from fuel cells, solar cells, ultracapacitors, and/or batteries. Especially solar cells are installed in HALE UAV and flight tests are performed in the stratosphere. Although the solar powered UAV has the advantage of zero emission, its energy conversion efficiency is low and operation time is limited. Therefore, the solar powered UAV has been designed to operate with the secondary battery obtaining flexibility of energy management. In this study, we suggest the new operational concept of the solar powered UAV using directed-energy rayed from the surface of earth to UAV. An UAV is able to secure additional power through attaching solar cell to the lower surface of elevator. As a result, the additional energy supplied by directed-energy can improve the energy management and operational flexibility of the solar powered UAV.

Effect of γ-Irradiation on the Molecular Properties of Bovine Serum Albumin and β-Lcatoglobulin

  • Cho, Yong-Sik;Song, Kyung-Bin
    • BMB Reports
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    • 제33권2호
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    • pp.133-137
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    • 2000
  • To elucidate the effect of oxygen radicals on the molecular properties of proteins, the secondary and tertiary structure and molecular weight size of BSA and ${\beta}$-lactoglobulin were examined after irradiation of proteins at various doses. Gamma-irradiation of protein solutions caused the disruption of the ordered structure of protein molecules as well as degradation, cross-linking, and aggregation of the polypeptide chains. As a model system, BSA and ${\beta}$-lactoglobulin were used as a typical ${\alpha}$-helical and a ${\beta}$-sheet structure protein, respectively. A circular dichroism study showed that the increase of radiation decreased the ordered structure of proteins with a concurrent increase of aperiodic structure content. Fluorescence spectroscopy indicated that irradiation quenched the emission intensity excited at 280 nm. SDS-PAGE and a gel permeation chromatography study indicated that radiation caused initial fragmentation of proteins resulting in a subsequent aggregation due to cross-linking of protein molecules.

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가스터빈 연소기 기본 설계 프로그램 개발 (Preliminary Design Program Development for Gas Turbine Combustor)

  • 김대식;김진아;진유인
    • 한국연소학회지
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    • 제20권3호
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    • pp.27-34
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    • 2015
  • The objective of the current study is to introduce detailed process for a preliminary combustor design, and to develop a computer code for it. The program includes various empirical and semi-empirical methodologies for diffuser deign, combustor sizing, air distribution, and sub-component design such as primary and secondary zones. Using the developed program, the combustor sizing results are shown from an assumption of simple annual combustor cycle analysis. Two options are employed, 1) pressure loss approach, and 2) velocity assumption approach. Design results show that there are no significant differences in combustor sizing between two design options. Further code improvement is required for performance and emission evaluations of the designed combustor.

전계방출광원에서 전도성 입자를 이용한 고효율 형광막 특성 연구 (Study on high efficient phosphor layer using conductive powder particle in field emission light source)

  • 정세정;김광복;이선희;김용원
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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    • pp.3-6
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    • 2007
  • The Light brightness is to enhance the luminescence efficiency of phosphor including conductive material. In preparing the anode layer, phosphors mixed with conductive material prepared with pastes of polymer resin using by screen printing method. When the prepared anode layer bombarded by cold electron from emitter of cathode, it give rise to form the secondary electron from those of conductive materials such as ITO powder. Furthermore, we are expect to enhance the luminescence efficiency more than without conductive material.

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스파트링 방법으로 제작된 MgO와 그 전기적 특성에 관한 연구 (The Study on the MgO thin film prepared by magnetron sputtering and its electrical characteristics)

  • 박정후;조정수;박명호
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 1997년도 제13회 학술발표회 논문개요집
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    • pp.169-172
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    • 1997
  • MgO dielectric pprotection layer is ppreppared by R.F. reactive magnetron spputtering with Mg target under various conditions of spputtering ppressure, time and substrate tempperature. Discharge characteristics of ppDpp is also studied as a pparameter of MgO pprepparation conditions. As the working ppressure and substrate tempperature was increase, the discharge voltage was decreased. Two kinds of MgO ppreppared both spputtering and E-beam methods were stable after annealing at 35$0^{\circ}C$ for 120min. discharge voltage under 3 mixed gas(He+Xe0.2%+Ne30%) was V=130V, V=102V and ${\gamma}$ coefficient was twiced as much as that of dielectric layer.

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Substructures of Galaxy Cluster Abell 2537

  • Lee, Jong Chul;Hwang, Ho Seong
    • 천문학회보
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    • 제39권2호
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    • pp.67.1-67.1
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    • 2014
  • Abell 2537 has been regarded as one of relaxed galaxy clusters because the X-ray emission is regular and symmetric, while there is also evidence to the contrary that the brightest cluster galaxy (BCG) is offset from the velocity center. To investigate the dynamical state of A2537 we obtain the redshift information of cluster galaxy candidates using Hectospec mounted on the MMT 6.5 m and compile those in the literature. The velocity distribution of member galaxies appears bimodal, with the main peak including the BCG and a secondary peak at velocity difference ~2000 km s-1. Based on the three-dimensional analysis and statistical tests we conclude that A2537 has at least two substructures and is not fully relaxed from a merger near the line-of-sight. We discuss more about the dynamical state of A2537 based on the color-magnitude diagram and X-ray scaling relation.

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