• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.5
• /
• pp.29-36
• /
• 2008

Diesel vehicle is growing in importance in light-duty sector as a way of reducing greenhouse gases due to improved fuel economy. Carbon monoxide, gas-phase hydrocarbon and organic fraction of diesel particulates can be oxidized to harmless products using a diesel warm-up catalyst (WCC). This study investigated the effect of a turbocharger and a baffle on flow fields and temperature distributions in the WCC for Diesel vehicles by a numerical analysis. In the case of the WCC with the turbocharger, velocity vectors and temperatures of inlet of the WCC have the relatively homogeneous distributions by the swirl generated from the turbocharger. Velocity vectors and temperatures of inlet of the WCC with the turbocharger and the baffle have the improved distributions in homogeneity compared with the case of the WCC without the baffle. The homogeneous flow field and the temperature distribution in the WCC may contribute to improve the conversion performance of the catalysts.

• Journal of Korean Society for Atmospheric Environment
• /
• v.20 no.4
• /
• pp.437-450
• /
• 2004

Extensive forest fire activities occurred across the border in Russia, particularly east of Lake Baikal between the Amur and Lena rivers in May 2003. These forest fires released large amounts of particulates and gases into the atmosphere, resulting in adverse effects on regional air quality and the global radiation budget. Smoke pollution from the Russian fires near Lake Baikal was transported to Korea through Mongolia and eastern China. On 20 May 2003, a number of large fires were burning in eastern Russian, producing a thick, widespread pall of smoke over much of Northeast Asia. In this study, separation technique was used for aerosol retrieval application with imagery from MODIS aboard TERRA satellites. MODIS true-color image shows the location of fires and the grayish color of the smoke plumes over Northeast Asia. Aerosol optical thckness (AOT) retrieved from the MODIS data were compared with fire hot spots, ground-based radiation data and TOMS -based aerosol index data. Large AOT, 2.0-5.0 was observed on 20 May 2003 over Korea due to the influence of the long range transport of smoke aerosol plume from the Russian fires, while surface observed fine mode of aerosol size distribution increased.

• Journal of Korean Society for Atmospheric Environment
• /
• v.8 no.2
• /
• pp.121-127
• /
• 1992

This study was carried out to investigate the features of air pollutants in rainwater and trace their transported trajectories from other countries. Chemical analysis data of rainwater and suspended particulates collected at Seoul, Kanghwa, and Taean for three years were used to evaluate the effects of long-range transport of air pollutants. Scavenging theory on washout and rainout effect during a rainy period was applied to estimate whether pollutants in the precipitation were long-range transported or not. On the other hand, precipitation weighted surface wind were evaluated to analyze the effect from local sources on atmospheric concentrations. As a result, contribution of air pollutants caused by anthropogenic sources in the precipitation which was identified to be long range transported was confirmed significantly high and trajectory of these pollutants was to be equivalent to 850mb isobar. Although concentration of acidifying components increased in the precipitation, neutralization by alkaline soil components such as $Ca^{2+}$ and $Mg^{2+}$ was conspicuous especially during Yellow-sand period.

• Journal of the Semiconductor & Display Technology
• /
• v.4 no.3 s.12
• /
• pp.29-33
• /
• 2005

As the integrated devices become more and more sophistcated, the diameter of wafers increased up to 300 mm and strict level of cleaning is necessary to remove the particulates on the surface of wafer. Therefore we need a new type of wet-station which can reduce DI water and chemical in the cleaning process. Moreover, it is important to control the temperature and the concentration of chemical in the wet-station. In the conventional chemical supply system, it is difficult not only to fit the mixing rate of chemicals in cleaning process, but also to fit the quantity and temperature. Thus, we propose a new chemicals supply system, which overcomes above problems by the analysis of fluid and thermal transfer on chemical supply system.

• Journal of Korean Society for Atmospheric Environment
• /
• v.10 no.2
• /
• pp.105-115
• /
• 1994

This study was conducted to assess the health risk of carcinogenic heavy metals such as arsenic, nickel, chromium and cadmium Ambient concentrations of these metals were measured bimonthly, during May 1987 to March 1988. Respirable Particle concentrations of As, Ni, Cr, Cd in traffic area(Shinchon) were 16ng/㎥, 43ng/㎥, 4.2ng/㎥, 6.6ng/㎥, respectively, and in residential area(Bulkwang) were 25ng/㎥, 32ng/㎥, 4.7ng/㎥, 8.9ng/㎥, respectively. Carcinogenic risk of each metal was calculated by multiplication of ambient concentration and unit risk of the metal which was referred to recent version of Integrated Risk Information System(IRIS). Sum of the risk from these for metals was 9.8$\times$10$^{-5}$ as individual risk in traffic area and 13.9$\times$10$^{-5}$ in residential area.

• Journal of Pharmaceutical Investigation
• /
• v.40 no.6
• /
• pp.373-378
• /
• 2010

In order to develop a topical preparation which has a high occlusive property with skin moisturization, nano-structured lipid carrier (NLC) systems along with solid lipid nanoparticle (SLN) were designed. Various NLC dispersions were successfully formulated with Compritol 888 ATO as a solid lipid, Labrafil M 1944 CS as an oil, and Tween 80 as a surfactant. The increase of oil content (5 to 50%) led to the decrease in the occlusion factor in the order of SLN > NLC-5 > NLC-15 = NLC-30 > NLC-50. Particle size of lipid particulates was in the range of 100 to 160 nm. NLC-based carbogels were prepared by the employment of humectants such as urea, glycerin, and Tinocare GL to carbomer gel. NLC-30 gel formulations containing 4 or 8 % of lipid particles showed improved occlusive effect in vitro, compared to NLC-free gel base. Even though NLC-free gel base revealed comparable occlusion effect by itself, the occlusion factor of 4 % NLC-30 gel was about 2-fold higher than that of NLC-free gel base.

• Journal of Korea Foundry Society
• /
• v.37 no.4
• /
• pp.115-122
• /
• 2017

The aim of this research is to evaluate the wear properties of (TiB+TiC) paticulate reinforced titanium matrix composites (TMCs) by in-situ synthesis. Different particle sizes (1500, $150{\mu}m$) and contents (0.94, 1.88 and 3.76 mass% for Ti, 1.98 and 3.96 mass% for the Ti6Al4V alloy) of boron carbide were added to pure titanium and to a Ti6Al4V alloy matrix during vacuum induction melting to provide 5, 10 and 20 vol.% (TiB+TiC) particulate reinforcement amounts. The wear behavior of the (TiB+TiC) particulate reinforced TMCs is described in detail with regard to the coefficient of friction, the hardness, and the degree of reinforcement fragmentation during sliding wear. The worn surfaces of each sliding wear condition are shown for the three types of wear studied here: transfer layer wear, particle cohesion wear and the development of abrasive areas. The fine reinforcements of TMCs were easily fragmented from the Ti matrix as compared to coarse reinforcements, and fragmented debris accelerated the decrease in the wear resistance.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.6
• /
• pp.1506-1508
• /
• 2010

$LiMnBO_3$ was successfully synthesized by a solid-state reaction method both with and without a carbon coating. Adipic acid was used as source material for the carbon coating. $LiMnBO_3$ was composed of many small polycrystalline particles with a size of about 50 - 70 nm, which showed a very even particle morphology and highly ordered crystalline particulates. Whereas the carbon coated $LiMnBO_3$ was well covered by mat-like, fine material consisting of amorphous carbon derived from the carbonization of adipic acid during the synthetic process. Carbon coated cell exhibited improved and stable discharge capacity profile over the untreated. Two cells delivered an initial discharge capacity of 111 and 58 mAh/g for $LiMnBO_3$/C and $LiMnBO_3$, respectively. Carbon coating on the surface of the $LiMnBO_3$ drastically improved discharge capacity due to the improved electric conductivity in the $LiMnBO_3$ material.

• Journal of Environmental Health Sciences
• /
• v.19 no.1
• /
• pp.37-43
• /
• 1993

The airborne concentrations of Sulfur Dioxide and Total Suspended Particulates were investigated in 4 subway lines in Seoul at early summer, 1990 and early summer, 1991. The results of the study were as follows: 1. The airborne concentrations of SO$_2$ and TSP were 0.022 ppm, 445.7 $\mu$g/m$^3$ respectively. And percents of over annual air quality standard of WHO was that SO$_2$ and TSP were 41.7%, 100% respectively. 2. Airborne SO$_2$ concentrations by subway lines were that line 1 was 0.025 ppm, line 2 was 0.023 ppm, line 3 was 0.020 ppm, and line 4 was 0.017 ppm. And TSP concentrations by subway lines were that line 2 was 533.8 $\mu$g/m$^3$, line 1 was 516.5 $\mu$g/m$^3$, line 4 was 371.6 $\mu$g/m$^3$, and line 3 was 369.3 $\mu$g/m$^3$ 3. Annual variation of concentration of TSP was not significant statistically (t=0.327), and that of SO$_2$, in 1990 was slightly higher than that in 1991 (t=1.433, p<0.1). 4. Coefficients of correlation between TSP and SO$_2$ by years were that early summer, 1990 was r=0.277 (p>0.1), and early summer, 1991 was r=0.32 (p>0.1).

• Proceedings of the SAREK Conference
• /
• 2008.11a
• /
• pp.541-545
• /
• 2008

Particulate matter (PM) is one of the major indoor air pollutants especially in the subway station in Korea. In order to remove PM in the subway station, several kinds of PM removal system such as roll-filter, auto-washable air filter, demister, and electrostatic precipitator re used in the air handling unit (AHU) of subway station. However, those systems are faced to operation and maintenance problems since the filter-regeneration unit consisting of electrical or water jet parts is malfunctioned due to the high load of particulates and the filter material needs periodic replacement. In this study, we surveyed the particle removal systems in order to develop the new system of particle removing can be adopted in the current AHU of subway station.