• Journal of Power System Engineering
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• v.20 no.5
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• pp.37-45
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• 2016

Exhaust gas recirculation has the advantage of being low-cost and easy to control of NOx emission. Therefore, it is most generally used to reduce NOx emission according to strengthen regulation. In the case of a non-road engine, such as the agricultural engine, since it mainly operate a middle or high-load state, NOx emission is decreased in accordance with the mapping range of the EGR rate, but results in an increase in the particulate matter which is caused to deposit and fouling problem of the EGR system. This problem has become an important issue for maintaining the performance of the engine, as well as emission performance. This study had examined the effects of cooler aging on the performance of heat transfer efficiency and NOx emission in non-road diesel engine. As a result of the EGR cooler aging during 200 hours engine operation, the cooling performance decreased about 25% compared with that of fresh cooler and the NOx emission increased about 14.6% on NRSC(non-road steady cycle) and 20% on NRTC(non-road transient cycle) compared with that of fresh cooler respectively.

• Journal of Environmental Health Sciences
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• v.24 no.3
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• pp.114-123
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• 1998

Particulate matters(less than 10 $\mu$m, PM10) at Kanghwa and Yangyang, which are located in the western and the eastern coastal regions in Korea, were measured in using low volume air sampler from December 1995 to November 1996, and their characteristics were investigated from the view point of background level.(and in order to characterize the particulate matters.) The particulate matters were analyzed for major water soluble ionic components(SO$_{4}^{2-}$, NO$_{3}^{-}$, Cl$^{-}$, Na$^{+}$, NH$_{4}^{+}$, K$^{+}$, Mg$^{2+}$ and Ca$^{2+}$) by ion chromatography. Mass concentrations of particulate matters were $48.77 \pm 22.45 \mug/m^{3}$ at Kanghwa and $54.04 \pm 32.98 \mug/m^{3}$ at Yangyang and SO$_{4}^{2-}$, NO$_{3}^{-}$ and NH$_{4}^{+}$ contributed largely to water soluble ionic components. nss(non sea salt)-SO$_{4}^{2-}$, contributed more than 95 percentage to SO$_{4}^{2-}$ and nss-K$^{+}$ and nss-Ca$^{2+}$ also contributed high percentages to K$^{+}$ and Ca$^{2+}$. It was supposed that most SO$_{4}^{2-}$, was originated from anthropogenic sources, and K$^{+}$ and Ca$^{+}$ were mainty originated from soil. The results of factor analysis suggested possibility of interpreting the correlation between air pollutants and regional characteristics.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.99-105
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• 2022

Public attention to the indoor environment of underground subway stations, which is a representative multi-use facility, has been increasing along with the increase in indoor activities. In underground stations, fine iron oxide, which affects the health of users, is generated because of the friction between wheels and rails. Among particulate pollutant reduction technologies, plants have been considered as a non-chemical air purification method, and their effects in reducing certain chemical species have been identified in previous studies. The present study aimed to derive the total quantitative and qualitative reduction effects of a bio-filter system comprising air purifying plants, installed in an underground subway station. The experiment proceeded in two ways. First, PM(particulate matter) reduction effect by vegetation biofilter was monitored with the IAQ(indoor air quality) station. In addition, chemical speciation analysis conducted on the samples collected from the experimental and control areas where plants and irrigation using SEM-EDS(scanning electron microscopy-energy dispersive X-ray spectroscopy). This study confirmed the effect of the vegetation bio-filter system in reducing the accumulation of particulate pollutants and transition and other metals that are harmful to the human body.

• Journal of environmental and Sanitary engineering
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• v.9 no.1
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• pp.53-61
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• 1994

Sungnam city, as a major satellite town, is located in the southeast of Seoul. Atmospheric conditions are so stable that air pollutants from various emissions are tend to resist change because Sungnam city is located in the Namhansansung valley. The industrial distribution of Sungnam city are composed of various manufactories such as foods, fibers, chemicals, machinery and electronics etc. The heavy metal concentrations and size distribution are the most important parameters influencing among the way in which respirable suspended particulate matter interact with the human respiratory system. Respirable suspended particulate matter was collected on glass fiber filters from April 1993 to February 1994 according to particle size using Anderson sampler during 10 days per month at Sungnam city. 6 heavy metals, Fe, Zn, Pb Mn, Cu and Cd, were analyzed by particle size with atomic absorption spectrophotometry . The results could be summarized as follows: 1. The annual arithmetic mean concentration of total suspended particulate was 116.3$\mu $g/m$^{3}$ m', seasonal variation was the highest in spring season(196.5$\mu $g/m$^{3}$) and the lowest in Summer Season(72.9$\mu $g/m$^{3}$). 2. The ratio of airborne particulate concentrations respirable to nonrepairable( Res/Non- Res) of annual arithmetic mean value was 5.8'1, seasonal variation was highest in the spring season(6.3 : 1) and lowest in the summer season(4.6 : 1). 3. During the spring season the shape of the size distribution was trimodal which showed peaks at 3 size groups, which were below of 0.43$\mu $m, 3.3∼4.7$\mu $m and above of 11.0$\mu $g/m$^{3}$ respectively. 4. Respirable suspended particulate matter concentrations of Zn, Pb Cu and Cd were the highest in below of 0.43$\mu $m as follows; 0.517$\mu $g/m$^{3}$, 0.411 $\mu $g/m$^{3}$, 0.062$\mu $g/m$^{3}$ and 0.0310$\mu $g/m$^{3}$ , respectively, Fe and Mn were the highest in the particle size range of 4.7 ∼ 7.0$\mu $m as follows; 2.504$\mu $g/m$^{3}$ and 0.095$\mu $g/m$^{3}$, respectively. 5. The Pt Cd, Zn, Cu, Fe and Mn concentrations of annual arithmetic mean value respirable to non- respirable( Res/Non- Res ) were 33.65, 19.27, 17.74, 10.54, 3.20 and 5.20, respectively.

• Journal of Soil and Groundwater Environment
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• v.16 no.6
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• pp.1-9
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• 2011

A bibliographical review of Gy sampling theory for particulate materials was conducted to provide readers with useful means to reduce errors in soil contamination investigation. According to the Gy theory, the errors caused by the heterogeneous nature of soil include; the fundamental error (FE) caused by physical and chemical constitutional heterogeneity, the grouping and segregation error (GE) aroused from gravitational force, long-range heterogeneous fluctuation error ($CE_2$), the periodic heterogeneity fluctuation error ($CE_3$), and the materialization error (ME) generated during physical process of sample treatment. However, the accurate estimation of $CE_2$ and $CE_3$ cannot be estimated easily and only increasing sampling locations can reduce the magnitude of the errors. In addition, incremental sampling is the only method to reduce GE while grab sampling should be avoided as it introduces uncertainty and errors to the sampling process. Correct preparation and operation of sampling tools are important factors in reducing the incremental delimitation error (DE) and extraction error (EE) which are resulted from physical processes in the sampling. Therefore, Gy sampling theory can be used efficiently in planning a strategy for soil investigations of non-volatile and non-reactive samples.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.484-489
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• 2012

The objective of this work presented here was focused on analysis of particulate matter and nitrogen oxide characteristics in ESC test mode from heavy-duty diesel engine installed on-road vehicles applicable to prime propulsion engine for marine vessels. The authors confirmed that a large quantity particulate matter were emitted in high power density condition, nitrogen oxide characteristics were dependent on exhaust gas temperature. Particulate matters were reduced by 1/100~1/1,000 times in post DPF with test modes but filtration efficiency was decreased in the engine power fluctuation. In the case of the high speed and power condition, the exhaust level of particulate matters was increased according to increment of temperature of gas flowing into DPF. The orders of magnitude for particle concentration levels from the analysis of size distribution of particulate matters of test engine was different. Both emitting nano-sized particles below 100nm regardless of DPF and non-DPF.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.2
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• pp.173-181
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• 1993

Seasonal distributions of nutrients and particulate organic matter were investigated in Asan Bay, Korea. Most of nutrients were high in August and low in February. The atomic ratios of inorganic nitrogen to phosphorous were close to Redfield ratio except in May when the ratio was 24.8. In May, nutrient concentrations except phosphorous decreased with salinity until $31.5{\sim}32.0%0$, but the concentrations increased again with salinity, impling that there were nutrient input sources within the estuary. Howerer, significant inverse relationships between nutrients and salinity in August suggest that nutrient sources were river discharge. Maximum chlorophyll a concentrations occurred in May. Relatively low ratios of $R_b$ to $R_a$($R_b$: fluorescence before acidification; $R_a$: fluorescence after acidification) during the study periods indicate that phytoplankton were not in good physiological condition. Relatively low ratio of particulate biogenic silica(PBSi) to particulate organic carbon(POC) and high ratios of PBSi and POC to chlorophyll a during the study periods suggest input of non-living detrital PBSi and POC from bottom in Asan Bay, where strong tidal mixing occurs.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.461-466
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• 2008

Because of their simplicity, efficiency, and economy, slow sand filters are appropriate means of water treatment for small water systems. In this study, the effect of filtration velocity and dirty skin (Schmutzdecke) was evaluated on the performance of turbidity removal. Also, removal characteristics of particulate were investigated in the case of the usage of non-woven fabric on the surface of sand and the application of PCF as pretreatment process. Comparative column tests were carried out for the various operation condition. From the result of column tests, filtration velocity had little effect on the turbidity removal rate. The formation of algal biofilm on the surface of media is helpful in turbidity removal, while non-woven fabric is not as effective as expected. The relative contribution of biomass and accumulated particulates to head loss development in slow sand filters requires further study.

• International Journal of Automotive Technology
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• v.8 no.2
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• pp.165-177
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• 2007

Predictions of diesel particulate filtration are typically made by modeling of a particle collection, and providing particle trapping levels in terms of a pressure drop. In the present study, a series of single channel diesel particulate filter (DPF) experiments are conducted, the pressure traces are inversely analyzed and essential filtration parameters are deducted for model closure. A DPF filtration model is formulated with a non-linear description of soot cake regression. Dependence of soot cake porosity, packing density, permeability, and soot density in filter walls on convective-diffusive particle transportation is examined. Sensitivity analysis was conducted on model parameters, relevant to the mode of transition. Soot cake porosity and soot packing density show low degrees of dispersion with respect to the Peclet number and have asymptotes at 0.97 and $70\;kg/m^3$, respectively, at high Peclet number. Soot density in the filter wall, which is inversely proportional to filter wall Peclet number, controls the filtration mode transition but exerts no influence on termination pressure drop. The percolation constant greatly alters the extent of pressure drop, but is insensitive to volumetric flow rate or temperature of exhaust gas at fixed operation mode.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.10a
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• pp.237-238
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• 2008