• Journal of Mechanical Science and Technology
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• 제20권11호
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• pp.1972-1979
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• 2006

This study was conducted in order to generate model particles which were similar to particles in diesel emission. Spark discharge was used for carbon agglomerates and hydrocarbon condensation for particles that consist of carbon agglomerates and hydrocarbon. The size of the carbon agglomerates, whose mean size were 30 and 70 nm, ranged between 15 and 200 nm, and the total number concentration of the particles ranged from 3 to $5{\times}10^7#/cm^3$ as the controllable variables in spark discharge generator changed. The result of the hydrocarbon condensation experiment showed that the final sizes of the particles enlarged by condensation did not depend on the initial sizes, but the maximum condensational growth of carbon agglomerates by dodecane ($C_{12}H_{26}$) condensation was 112 times the initial size of 40 nm, while the size of the agglomerates by benzene ($C_6H_6$) was 3.25 times its initial size.

• 한국환경보건학회지
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• 제38권5호
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• pp.393-397
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• 2012

Objectives: The objectives of this study were to measure passengers' exposure to ultrafine particles (UFP) and to determine effects of fuel, operating condition and position of seat. Method: UFP exposures in front and back seats of the Elephant vehicle in Seoul Grand Park were simultaneously measured by a condensation particle counter (P-Trak model 8525, TSI). The measurements were conducted 7 times with diesel-powered vehicle and 3 times with electricity vehicle in one day. The vehicle stopped at 3 locations along with 2.2 km of driving route. Results: UFP concentration in diesel-powered vehicle was significantly higher than electricity vehicle. At front seat of diesel-powered vehicle, average UFP exposure during stopping was significantly higher than during moving. When diesel-powered vehicle moved, UFP exposure in back seat was significantly higher than in front seat. Conclusions: Passengers in the diesel-powered Elephant vehicle could be exposed to high level of UFP. The UFP exposure was associated with operation condition and position of seat.

• 한국약용작물학회지
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• 제20권2호
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• pp.129-135
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• 2012

The feature of asthma are airway inflammation (AI), reversible airway obstruction, and an increased sensitivity to bronchoconstricting agents, elevated airway hyperresponsiveness (AHR), excess production of Th2 cytokines, and eosinophil accumulation in the lungs. This study was performed to investigate if oral administration of $Scutellaria$ $baicalensis$ Georgi water extracts (SBG) have the antiasthmatic potential for the treatment of asthma. Asthmatic HI and AHR were induced by systemic sensitization to ovalbumin (OVA) with intratracheal instillation with 0.1 mg/mL of diesel exhaust particles (DEP) suspension once a week for 10 weeks in BALB/c mice. SBG was orally administered with the concentraion of 200 mg/kg 5 days a week for 10 weeks. Long-term SBG treatment suppressed the eosinophil infiltration into airways from blood, the asthmatic AI and AHR by attenuating the production of cytokine IL-4, IL-5 and IL-13, histamine and OVA-specific IgE. Our data suggest that SBG has inhibitory effects on AI and AHR in a mouse model of asthma, may act as a potential Th2 cytokine antagonist, and may have a therapeutic effect on allergic asthma.

• Environmental Analysis Health and Toxicology
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• 제21권2호
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• pp.127-138
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• 2006

In urban areas, diesel exhaust particles (DEP) are probably a major component of particulate matters, especially in Korea where drive many diesel vehicles. The aim of this study was to investigate genotoxic effects of DEP using single ceil gel electrophoresis. In order to evaluate the mechanisms of DEP genotoxicity, the rat microsome mediated and DNA repair enzyme treated comet assays together with conventional comet assay were performed. Total diesel particles (DEPT) was collected without site fractionation from diesel engine bus and dichloromethane extract was obtained. The organic extract of DEPT revealed DNA damage itself in NIH/3T3 cells. The level of DNA breaks plus oxidative DNA lesions and microsome mediated DNA damage was assessed by modified single cell gel eletrophoresis. DEPT was able to induce oxidative DNA damage as well as microsome mediated DNA damage. Vitamin C as an model antioxidant reduced DNA damage in endonuclase III treated comet assay. One of flavonoid, galangin as a CYP1A1 inhibitor. reduced DNA damage in the presence of S-9 mixture. $DEP_T$ is the sources of oxidative stress, but antioxidants can significantly reduce oxidative DNA dmage. And $DEP_T$ may contain indirect mutagens which can be inhibited by CYP1A1 inhibitors. The ethanol extracts of the mixed vegetables (BV) or the mixed fruits (BF) were evaluated for their in vitro antigenotoxic effects. BV and BF showed potent Inhibitory effects against DEPT induced DNA damage with oxidative DNA lesions and in the prescence of S-9 mixture. These results indicate that BV and BF could prevent cellular DNA damage by inhibiting oxidative stress and suppressing cytochrome P4501A1 in cell culture.

• 수산해양기술연구
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• 제24권1호
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• pp.36-43
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• 1988

Boilers and diesel engines have many problems because their exhaust particles, i.e., soot have lots of bad influence on environment. And it's spray and flame have fundamentally axial symmetric shape. To investigate the relationship between fuel concentration distribution of spray and soot concentration distribution as well as temperature distribution of flame, we made a axial symmetric two phase spray-flame and analyzed the structure of is. The measuring method is the principle of the light extinction method for the spray-flame and onion peeling model is applied to analyze the radial distribution of fuel and soot concentration. The temperature of flame is measured by ø 0.4mm Pt-Pt.RH 3% thermocouple. The oils for the experiments are diesel oil and 10% water emulsified diesel oil. It was found that the soot concentration becomes higher as it comes near to the center of flame, and the fuel concentration does, too. And the soot concentration level of diesel oil is generally higher than that of the 10% water emulsified fuel. The maximum flame temperature of diesel oil is 1,17$0^{\circ}C$, however, 10% water emulsified diesel oil is 1,27$0^{\circ}C$.

• 대한본초학회지
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• 제28권1호
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• pp.65-71
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• 2013

Objectives : Asthma is a chronic, complex respiratory disease, caused by airway obstruction, airway eosinophilic inflammation(AEI), and airway hyperresponsiveness(AHR). This study was conducted to determine whether oral administration of crude water extracts of Pinellia ternate Breitenbach(PTB) has an antiasthmatic potential in the treatment of asthma in mice. Methods : Asthmatic AEI and AHR were induced by systemic sensitization to ovalbumin(OVA) by intratracheal instillation with 0.1 mg/mL suspension of diesel exhaust particles(DEP) once a week for 10 weeks in BALB/c mice. Crude PTB water extracts(50 mg/kg and 200 mg/kg) were orally administered 5 times a week for 10 weeks. Cyclosporin(10 mg/kg) was administrered the same manner as a positive control. Results : Long-term treatment with crude PTB water extracts suppressed the infiltration of inflammatory cells, including eosinophils, into airways from blood. It also reduced asthmatic AEI and AHR by attenuating the increase in the levels of cytokines such as interleukin(IL)-4, IL-5 and IL-13 in bronchoalveolar lavage fluid(BALF), as well as the levels of histamine and OVA-specific IgE in blood. However, the effect of crude PTB water extracts(200 mg/kg) was not likely to be stronger than that of cyclosporin(10 mg/kg). Conclusion : These results suggest that crude PTB water extracts have inhibitory effects on AEI and AHR in a mouse model of asthma and may act as a potential Th2 cytokine antagonist, and have a therapeutic effect on allergic asthma.

• 한국토양환경학회지
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• 제4권2호
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• pp.137-147
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• 1999

Cahn-balance에 의한 TGA(thermal gravimetric analysis)와 heat pipe가 내삽된 유동상 탈착 시스템을 이용한 실험 및 이론적 고찰을 통해 유동상 열탈착조에서 디젤오염토양의 열탈착 모델링을 확립하였다. 유류에 오염된 토양의 탈착 특성을 살펴본 결과, 비다공성(nonporous)토양("soil A")의 경우 유류 탈착 빠르게 진행되는데 반해서 다공성(porous)토양("soil B")의 경우 탈착이 지연되는 현상을 관측하였는데 이는 내부 기공에서 탈착된 유류성분이 외부로 빠져 나오는데 걸리는 시간이 비다공성 토양에 비해 상대적으로 길기 때문으로 사료된다. 또한, 확산지배 탈착 영역에서는 탈착속도는 탈착가스의 유속과는 거의 상관없는 경향을 보였다. 연속식 유동상에서의 탈착효율에 영향을 미치는 변수는 탈착조 온도, 유속, 토양 공급량 이였다. 모든 온도 범위 내에서, 유동화속도가 클수록 잔류오일의 양이 감소하는, 즉 탈착효율이 증가하는 경향을 보였다. 특히 낮은 탈착온도 일수록 유동화 유속의 증가에 따라 뚜렷한 탈착효율의 증가효과를 관측할 수 있었다. 반면에 일정한 유속 하에서 토양공급 속도의 증가에 따라 탈착 효율은 감소하였다. 공급속도가 높을 때에는 온도와는 상관없이 잔류오염물의 농도가 대체적으로 높았는데, 이는 screw feeder를 통해 유입되는 오염토양이 충분한 체류시간을 거치지 않고 빠져나감으로써 충분한 열적 교환 및 물질이동이 이루어지지 않았음을 나타내주고 있다. 본 연구에서는 Fickian 확산계수를 결합시킨 Kunii-Levenspiel 모델을 통하여 유동화 속도에 따른 오염토양의 탈착 경향을 살퍼본 결과 탈착 효율 $A_X$는 전체 물질전달계수 (${K_d}_f$)와 유체유속과 기포상 승속도의 비($u_o$$u_b$)의 변화에 크게 영향을 받는 것으로 나타났다. 모델링의 예측 결과로부터 유동층내의 확산 지배에 의한 오염토양의 탈착효율은 여러 조업변수의 조합에 의해 최적화 할 수 있음을 알 수 있었고, 아주 낮은 최소 유동화속도에서도 높은 탈착효율을 얻을 수 있다는 사실을 확인하였다. 얻을 수 있다는 사실을 확인하였다.

• 한국분무공학회지
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• 제21권4호
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• pp.223-236
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• 2016

On-road source emissions are major air pollutants and have been associated with serious health effects in Seoul metropolis. Thus, it is of fundamental importance to have an accurate assessment of vehicle emissions in order to implement an effective air quality management policy. As a result, there is a need to overview vehicle emission characteristics of air pollutants. This article discusses vehicle exhaust sampling and chemical analysis, emission characteristics of air pollutants, and emission regulations from passenger cars. The vehicle exhaust sampling and chemical analysis methods were described in particulate matter and gaseous compounds. In this article, chassis dynamometer, measurement instrumentation for nano-particulate matter and carbon compounds analysis device were described. For the gasoline and diesel vehicles, the effective parameters of emissions were average vehicle speed, vehicle mileage and model year. The particle number emissions for diesel nano-particles were sensitive to the sampling conditions. Also, the particle number emissions with a diesel particle filter (DPF) largely reduced rather than those without it. This article also describes different emission characteristics of air pollutants according to biodiesel or bioethanol mixing ratio. The Korean emission standards for passenger cars were compared with those of the US and EU. Finally, the objective is to give an overview of relevant background information on emission characteristics of air pollutants from passenger cars in Korea.

• Asian Journal of Atmospheric Environment
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• 제2권2호
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• pp.90-101
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• 2008

The chemical compositions of $PM_{2.5}$ and $PM_{10}$ and associated high-molecular-weight polycyclic aromatic hydrocarbons (PAHs) were investigated during winter and summer at a roadside and an urban background site in Saitama, Japan. The average concentrations of $PM_{2.5}$ exceeded the United States Environmental Protection Agency standards during both periods. Carbonaceous components were abundant in both the observed and calculated (by means of a mass closure model) chemical composition of $PM_{2.5}$. Traffic-related pollutants (elemental carbon and high-molecular-weight PAHs) were strongly associated with $PM_{2.5}$ rather than with larger particles. The mass concentrations of $PM_{2.5}$, as well as those of EC and PAHs associated with the particles, at the two sites were strongly correlated. Comparison of our data with source profile ratios indicates that diesel-powered vehicles were probably the main source of the measured PAHs. The PAHs concentrations were affected by meteorological conditions during our study. Our results highlight the need for the establishment of standards for $PM_{2.5}$ in Japan.

• 동력기계공학회지
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• 제13권6호
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• pp.13-21
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• 2009

This basic study is required to examine spray or jet behavior depending on fuel phase. In this study, analyses of diesel fuel(n-Tridecane, $C_{13}H_{28}$) spray and natural gas fuel(Methane, $CH_4$) jet under high temperature and pressure are performed by a general-purpose program, ANSYS CFX release 11.0, and the results of these are compared with experimental results of diesel fuel spray using the exciplex fluorescence method. The simulation results of diesel spray is analyzed by using the combination of Large-Eddy Simulation(LES) and Lagrangian Particle Tracking(LPT) and of a natural gas jet is analyzed by using Multi-Component Model(MCM). There are two study variables considered, that is, ambient pressure and injection pressure. In a macroscopic analysis, the higher ambient pressure is, the shorter spray or jet tip penetration is at each time after start of injection. And the higher injection pressure is, the longer spray or jet tip penetration is at each time after start of injection. When liquid fuel is injected, droplets of the fuel need some time to evaporate. However, when natural gas fuel is injected, the fuel does not need time to evaporate. Gas fuel consists of minute particles. Therefore, the gas fuel is mixed with the ambient gas more quickly at the initial time of injection than the liquid fuel is done. The experimental results also validate the usefulness of this analysis.