• Title/Summary/Keyword: Carbon particle

Search Result 1,034, Processing Time 0.02 seconds

Basics of particle therapy II: relative biological effectiveness

  • Choi, Jin-Hyun;Kang, Jin-Oh
    • Radiation Oncology Journal
    • /
    • v.30 no.1
    • /
    • pp.1-13
    • /
    • 2012
  • In the previous review, the physical aspect of heavy particles, with a focus on the carbon beam was introduced. Particle beam therapy has many potential advantages for cancer treatment without increasing severe side effects in normal tissue, these kinds of radiation have different biologic characteristics and have advantages over using conventional photon beam radiation during treatment. The relative biological effectiveness (RBE) is used for many biological, clinical endpoints among different radiation types and is the only convenient way to transfer the clinical experience in radiotherapy with photons to another type of radiation therapy. However, the RBE varies dependent on the energy of the beam, the fractionation, cell types, oxygenation status, and the biological endpoint studied. Thus this review describes the concerns about RBE related to particle beam to increase interests of the Korean radiation oncologists' society.

Measurement and Analysis of Visibility lmpairment during June, 1994 in Seoul (1994년 6월 서울지역 시정장애의 측정 및 분석)

  • 백남준;이종훈;김용표;문길주
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.12 no.4
    • /
    • pp.407-419
    • /
    • 1996
  • Characteristics of visual air quality in Seoul have been investigated between June 13 and 21, 1994. Optical properties (extinction coefficient and particle scattering coefficient), meteorological parameters (relative humidity, temperature, wind speed, wind direction, and cloud cover), particle characteristics (mass size distribution, components) were measured and analyzed. During measurement periods, northwest wind with less than 2m/sec of wind speed deteriorates visibility. Effects of relative humidity are though to be not a direct factor which influence to visibility through the size change due to hygroscopic species in aerosol. During the smoggy period both the aerosol mass concentration and fine particle fraction of the size distribution are increased compared to the clear period. Sulfate, organic carbon, and elemental carbon in aerosol are the major species in determining the occurrence and severity of a smog in Seoul.

  • PDF

Monitoring Airborne Nanoparticle Concentrations by Task in a Laboratory Making Carbon Nanotube Films (탄소나노튜브 필름 제조 실험실의 세부작업별 공기 중 나노입자 노출 농도)

  • Ha, Ju-Hyun;Shin, Yong-Chul
    • Journal of Korean Society of Occupational and Environmental Hygiene
    • /
    • v.20 no.4
    • /
    • pp.248-255
    • /
    • 2010
  • Airborne nanoparticle concentrations in three metrics (particle surface area concentration, particle number concentration, and particle mass concentrations) were measured by task in a laboratory making carbon nanotubes (CNTs) films using three direct reading instruments. Because of the conducted other researcher's experiment before the tasks, airborne nanoparticle surface area and number concentrations are the highest at the first time conducted weighing and mixing by sonication task, respectively. Because of the mist generated during mixing by sonication, the highest airborne nanoparticle surface area and PM1 concentrations were measured in the task among the total. Nanoparticle surface area concentrations at the researchers' breathing zones had high correlation (r=0.93, p<0.01) with those measured at an area in the laboratory. This result indicates that nanoparticles generated during the experiment contaminated the whole room air. When the experiment performed all the fume hoods weren't operated and making CNTs films task were conducted in the out of the fume hoods. In conclusion, researchers performing making CNTs film experiments were exposed to airborne nanoparticles generated during the experiment without adequate controls. We recommend that adequate controls should be implemented so that workers' exposures to airborne nanoparticle are limited to minimum levels.

A Study on Synthesis of High Purity $\beta$-SiC Fine Particle from Ethylsilicate(I) -Reaction Conditon, Yeild and Properties of $\beta$-SiC- (Ethyl Silicate를 고순도 $\beta$-SiC미분말 합성에 관한 연구(I) 반응조건과 $\beta$-SiC의 생성율 및 특성)

  • 최용식;박금철
    • Journal of the Korean Ceramic Society
    • /
    • v.25 no.5
    • /
    • pp.473-478
    • /
    • 1988
  • In order to obtain the high purity $\beta$-SiC powder that possesses the excellent sinterability and is close to the spherical shape, the carbon black was mixed into the composition of Si(OC2H5)4-H2O-NH3-C2H5OH which the monodispersed spherical fine particles is formed the hydrolysis of Ethylsilicate and the mixture was carbonized under an argon atmosphere. Particle shpae, size and the yield of $\beta$-SiC powder were investigated according to the molar ratio of carbon/alkoxide and variations of reaction temperature and reaction time. The results of this study are as follow ; 1) The yield of $\beta$-SiC gained from the reaction for one hour at 150$0^{\circ}C$ almost got near 100% and the particle size of $\beta$-SiC from the reaction for 15 hrs at 150$0^{\circ}C$ was 0.2${\mu}{\textrm}{m}$ on the average and close to the spherical shape agglomerate state. 2) When the molar ratio carbon/alkoxide is over 3.1 and the reaction occurs at 145$0^{\circ}C$ for 5hrs, the carbon content has not an effect on the kind of crystal of product.

  • PDF

Effect of CNT Particle Dispersion in CNT Paste on Field Emission Characteristics in Carbon Nanotube Cathode (탄소나노튜브의 분산이 탄소나노튜브 캐소드의 전계방출 특성에 미치는 영향)

  • Ahn B. G.;Seung M. S.;Shin H. Y.;Kim D. H.;Kim T. S.;Cho Y. R.
    • Korean Journal of Materials Research
    • /
    • v.14 no.11
    • /
    • pp.807-812
    • /
    • 2004
  • The uniformity of emission mage and field emission properties of carbon nanotube(CNT) cathodes dependence on CNT particle dispersion were investigated for field emission displays. We used multi-walled carbon nanotubes (MWNTs) synthesized by CVD method as the field emitter materials. CNT dispersion in CNT ink was carried out by ultrasonication and shaking methods. According to CNT dispersion conditions, the uniformity of emission image and field emission properties of CNT cathodes were greatly affected. The smaller particles of filler materials and CNT powders provide the better properties of the CNT cathodes.

The Calibration Method of Time Resolved Laser Induced Incandescence Using Carbon Black Particles for the Soot Measurement at Exhaust Tail Pipe in Engine (엔진 배기단 적용을 위한 Time Resolved Laser Induced Icandescence (TIRE-LII) 신호의 보정 : 카본 입자 이용)

  • Oh Kwang Chul;Kim Deok Jin;Lee Chun Hwan;Lee Chun Beom
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.29 no.12 s.243
    • /
    • pp.1335-1343
    • /
    • 2005
  • The calibration technique of Time Resolved Laser Induced Incandescence was investigated both experimentally and numerically by using standard-sized carbon black particles for the instantaneous soot measurement at exhaust tail pipe in engine. The carbon black particles (19nm, 25nm, 45nm and 58nm) used in this study are similar, though not identical, to soot particle generated from flame not only in morphology but also in micro-structure. The amount of soot loading in flow was controled by a diluted gas (nitrogen) and was measured by the gravimetric method at exhaust pipe in calibrator. The successful calibrations of primary particle size and soot mass fraction were carried out at the range from 19nm to 58nm and from $0.25mg/m^3$ to $37mg/m^3$ respectively. And based on these results the numerical simulation of LII signal was tuned and the effect of an exhaust temperature variation on the decay rate of LII signal was corrected.

Effect of Anion Generating Air Cleaner on the Components of ETS in a Closed Room (음이온 발생 공기청정기에 의한 밀폐된 실내공간에서의 ETS성분 변화)

  • Hwang, Keon-Joong;Rhee, Moon-Soo;Ra, Do-Young
    • Journal of the Korean Society of Tobacco Science
    • /
    • v.20 no.1
    • /
    • pp.124-130
    • /
    • 1998
  • This study was conducted to evaluate the ability of anion generating air cleaner to remove gases, vapor and particles from closed room contaminated with environmental tobacco smoke (ETS). The measurements covered particle sizes of 13.8-542.5nm, particle concentration, surface area, volumes UVPM, FPM, solanesol, and the following gases and vapor; carbon dioxide, carbon monoxide, nicotine, and 3-ethenylpyridine. Tobacco smoke was generated and mixed in a closed room in which the airflow rates were in the range of 0.00-0.04 m/s. The anion generating air cleaner was startedl and the decay rates for the gases, vapor and particles were measured, When the use of anion generating air cleaner, solid components of ETS, such as respirable suspended particle (RSP), utraviolet particulate matter (UVPM, fluorescent particulate matter (FPM) and solanesol was sharply decreased, and vapor phase components of ETS, such as nicotines 3-ethenylpyidine were modelately decreased by time elapse. Even the use of anion generation air cleaner, the decreasing rate of carbon dioxide concentration was similar with control, and the decreasing rate of carbon monoxide was slower than that of control. Our results indicated that the use of anion generting air cleaner had an effect on reduction of solid and vapor components from ETs, but it had no effect on gaseous components of ETS.

  • PDF

The Optimal Operation for Community Energy System Using a Low-Carbon Paradigm with Phase-Type Particle Swarm Optimization

  • Kim, Sung-Yul;Bae, In-Su;Kim, Jin-O
    • Journal of Electrical Engineering and Technology
    • /
    • v.5 no.4
    • /
    • pp.530-537
    • /
    • 2010
  • By development of renewable energy and more efficient facilities in an increasingly deregulated electricity market, the operation cost of distributed generation (DG) is becoming more competitive. International environmental regulations of the leaking carbon become effective to reinforce global efforts for a low-carbon paradigm. Through increased DG, operators of DG are able to supply electric power to customers who are connected directly to DG as well as loads that are connected to entire network. In this situation, a community energy system (CES) with DGs is a new participant in the energy market. DG's purchase price from the market is different from the DG's sales price to the market due to transmission service charges and other costs. Therefore, CES who owns DGs has to control the produced electric power per hourly period in order to maximize profit. Considering the international environment regulations, CE will be an important element to decide the marginal cost of generators as well as the classified fuel unit cost and unit's efficiency. This paper introduces the optimal operation of CES's DG connected to the distribution network considering CE. The purpose of optimization is to maximize the profit of CES. A Particle Swarm Optimization (PSO) will be used to solve this complicated problem. The optimal operation of DG represented in this paper would guide CES and system operators in determining the decision making criteria.

Reduction Characteristics of Mass Produced Particle for Chemical-Looping Combustor with Different Fuels (매체순환식 가스연소기용 대량생산입자의 연료별 환원반응특성)

  • Ryu, Ho-Jung;Kim, Kyung-Su;Lee, Seung-Yong;Park, Yeong-Seong;Park, Moon-Hee
    • Journal of Hydrogen and New Energy
    • /
    • v.19 no.4
    • /
    • pp.348-358
    • /
    • 2008
  • Reduction reactivity and carbon deposition characteristics of mass produced oxygen carrier particle(OCN-650) have been investigated by using hydrogen, methane, syngas, and natural gas as fuels. For all fuels, the maximum conversion and oxygen transfer capacity increased as the temperature increase. The reduction rate and the oxygen transfer rate increased as the temperature increase for methane. However, those values showed maximum at 900$^{\circ}C$ for hydrogen, syngas, and natural gas. To explain consistently the change of maximum conversion, reduction rate, oxygen transfer capacity, oxygen transfer rate and degree of carbon deposition for different fuels, new parameters such as reactive carbon contents and require oxygen per input gas were adopted.

Downward particle flux in the eastern Bransfield Strait, Antarctica

  • Kim, Dongseon;Kim, Dong-Yup;Jeonghee Shim;Kang, Young-Chul;Kim, Taerim
    • Journal of the korean society of oceanography
    • /
    • v.38 no.1
    • /
    • pp.1-10
    • /
    • 2003
  • A time-series sediment trap was deployed at a depth of 1034 m in the eastern Bransfield Strait from December 25, 1998 to December 24, 1999. Particle fluxes showed large seasonal variation; about 99% of the annual total mass flux (49 g m/sup -2/) was collected during the austral summer and fall (January-March). Settling particles consisted primarily of biogenic silica, organic carbon, calcium carbonate, and lithogenic material. Biogenic silica and lithogenic material predominated settling particles, comprising 36% and 30% of the total mass flux, respectively, followed by organic carbon, 11% and calcium carbonate, merely 0.6%. The annual organic carbon flux was 5.4 g C m/sup -2/ at 1000 m in the eastern Bransfield Strait, which is greater than the central Strait flux. The relatively lower flux of organic carbon in the central Bransfield Strait may be caused by a stronger surface current in this region. Organic carbon flux estimates in the eastern Bransfield Strait are the highest in the Southern Ocean, perhaps because of the fast sinking of fecal pellets, which leads to less decomposition of organic material in the water column. Approximately 5.8% of the organic carbon produced on the surface in the eastern Bransfield Strait is exported down to 1000 m; this percentage exceeds the maximum EF/sub 1000/ values observed in the Atlantic and Southern Oceans. The eastern Bransfield Strait appears to be the most important site of organic carbon export to the deep sea in the Southern Ocean.