• Journal of Korean Society on Water Environment
• /
• v.40 no.2
• /
• pp.79-88
• /
• 2024

This study employed field measurements and biogeochemical analysis to examine the effects of seasonal conditions (e.g., temperature and precipitation) and human intervention (e.g., dam or weir construction) on the chemical composition of dissolved organic matter, flocculation kinetics of suspended particulate matter, and formation of the fluid mud layer on riverbeds. The results indicated that a water environment with a substantial amount of biopolymers offered favorable conditions for flocculation kinetics during an algal bloom period in summer; a thick fluid mud layer was found to be predominated with cohesive materials during this period. However, after high rainfall, a substantial influx of terrigenous humic substances led to enhanced stabilization of the particulate matter, thereby decreasing flocculation and deposition, and the reduced biopolymer composition served to weaken the erosion resistance of the fluid mud on the riverbed. Moreover, a high-turbulence condition disaggregated the flocs and the fluid mud layer and resuspended the suspended particulate matter in the water column. This study demonstrates the mutual relationship that exists between biogeochemistry, flocculation kinetics, and the formation of the fluid mud layer on the riverine area during different seasons and under varying hydrological conditions. These findings are expected to eventually help inform the more optimal management of water resources, which is an urgent task in the face of anthropogenic stressors and climate change.

• Journal of ILASS-Korea
• /
• v.18 no.1
• /
• pp.21-26
• /
• 2013

Diesel low temperature combustion (LTC) is the concept where fuel is burned at a low temperature oxidation regime so that $NO_x$ and particulate matters (PM) can simultaneously be reduced. There are two ways to realize low temperature combustion in compression ignition engines. One is to supply a large amount of EGR gas combined with advanced fuel injection timing. The other is to use a moderate level of EGR with fuel injection at near TDC which is generally called Modulated kinetics (MK) method. In this study, the effects of fuel injection pressure on performance and emissions of a single cylinder engine were evaluated using the latter approach. The engine test results show that MK operations were successfully achieved over a range of with 950 to 1050 bar in injection pressure with 16% $O_2$ concentration, and $NO_x$ and PM were significantly suppressed at the same time. In addition, with an increase in fuel injection pressure, the levels of smoke, THC and CO were decreased while $NO_x$ emissions were increased. Moreover, as fuel injection timing retarded to TDC, more THC and CO emissions were generated, but smoke and $NO_x$ were decreased.

• Particle and aerosol research
• /
• v.4 no.2
• /
• pp.51-67
• /
• 2008

In this study, we devoted to kinetic measurement of the catalytic oxidation of iron-containing flame soot particles and better understanding the role of catalytic particles on carbon oxidation in particular at low temperature, targeting on autothermal regeneration of diesel particulate filter by diesel exhaust gas. Carbon-based Fe-containing particles generated by spraying ferrocene-doped diesel fuel in an oxy-hydrogen flame are tested and compared with a commercial carbon black powder for thermogravimetric analysis (TGA), secondary ion mass spectrometry (SIMS), Fourier-transform infrared spectroscopy (FTIR), Induced coupled plasma-Atomic emission spectroscopy (ICP-AES), and High-resolution transmission electron microscopy (HR-TEM). As a result, we found that a small amount of the ferrocene addition led to significant reductions in a on-set temperature and an activation energy of the carbon oxidation as well. An oxygenated surface complex forming at the particle surface could be thought as active species that would be readily consumed in particular at low temperature.

• Journal of environmental and Sanitary engineering
• /
• v.17 no.3
• /
• pp.115-120
• /
• 2002

This study was performed on a questionnaire survey of 500 people about their awareness for indoor air pollution, and measured efficiency of air cleaner which can remove the CO and air-borne particulate of ETS(Environmental Tobacco Smoke) in air clean chamber. The room-size cleaner for measuring indoor air contaminants has been applied to evaluation of two different air cleaner such as the mechanic air cleaner with hepafilter(HPA) and the electrostatic air cleaner with metal plate. The measuring experiment was carried out in a chamber by sampling the air. The results obtained were as follows; As respondents are having their 90% of daytime indoors a day, and 38% of them can feel indoor air pollutions degrees directly by their sense of smell, For the installation of indoor pollution control equipment, 34% of all respondents installed air cleaner because of the problem of economical charge and almost respondents was not satisfied the trust of ability purified indoor air pollutants. In the experimental results, it was found that more than 95% of CD and air-borne particulate of ETS were removed within 20 minutes. The reaction kinetics of removal pollutants was verified as the pseudo-first order, Finally, it appeared that the room-sire air cleaner can be applied to new technology for removing indoor air contaminants.

• Journal of Sensor Science and Technology
• /
• v.32 no.3
• /
• pp.147-153
• /
• 2023

Metal-organic frameworks (MOFs) of cobalt gallate were synthesized and deposited on gold electrodes using self-assembly monolayers (SAMs) and hydrothermal processing. These MOF films exhibit strong adsorption capabilities for gaseous particulates, and the use of SAMs allows the synthesis and deposition processes to be completed in a single step. When cobalt gallate is mixed with SAMs, a coordination bond is formed between the cobalt ion and the carboxylate or hydroxyl groups of the SAMs, particularly under hydrothermal conditions. Additionally, the quartz crystal microbalance (QCM) gas sensor accurately measures the number of particulates adsorbed on the MOF films in real-time. Thus, the QCM gas sensor is a valuable tool for quantitatively measuring gases, such as SO₂, NO₂, and CO₂. Furthermore, the QCM MOF film gas sensor was more effective for gas adsorption than the MOF particles alone and allowed the accurate modeling of gas adsorption. Moreover, the QCM MOF films accurately detect the adsorption-desorption mechanisms of SO₂ and NO₂, which exist as gaseous particulate matter, at specific gas concentrations.

• Korean Journal of Environmental Agriculture
• /
• v.35 no.2
• /
• pp.128-136
• /
• 2016

BACKGROUND: Hydrothermal carbonization reaction is the thermo-chemical energy conversion technology for producing the solid fuel of high carbon density from organic wastes. The hydrothermal carbonization reaction is accompanied by the thermal hydrolysis reaction which converse particulate organic matters to soluble forms (hydro-thermal hydrolysate). Recently, hydrothermal carbonization is adopted as a pre-treatment technology to improve anaerobic digestion efficiency. This research was carried out to assess the effects of hydro-thermal reaction temperature on the methane potential and anaerobic biodegradability in the thermal hydrolysate of organic sludge generating from the wastewater treatment plant of poultry slaughterhouse .METHODS AND RESULTS: Wastewater treatment sludge cake of poultry slaughterhouse was treated in the different hydro-thermal reaction temperature of 170, 180, 190, 200, and 220℃. Theoretical and experimental methane potential for each hydro-thermal hydrolysate were measured. Then, the organic substance fractions of hydro-thermal hydrolysate were characterized by the optimization of the parallel first order kinetics model. The increase of hydro-thermal reaction temperature from 170℃ to 220℃ caused the enhancement of hydrolysis efficiency. And the methane potential showed the maximum value of 0.381 Nm³ kg^-1-VS_added in the hydro-thermal reaction temperature of 190℃. Biodegradable volatile solid(VSB) content have accounted for 66.41% in 170℃, 72.70% in 180℃, 79.78% in 190℃, 67.05% in 200℃, and 70.31% in 220℃, respectively. The persistent VS content increased with hydro-thermal reaction temperature, which occupied 0.18% for 170℃, 2.96% for 180℃, 6.32% for 190℃, 17.52% for 200℃, and 20.55% for 220℃.CONCLUSION: Biodegradable volatile solid showed the highest amount in the hydro-thermal reaction temperature of 190℃, and then, the optimum hydro-thermal reaction temperature for organic sludge was assessed as 190℃ in the aspect of the methane production. The rise of hydro-thermal reaction temperature caused increase of persistent organic matter content.

• Asian-Australasian Journal of Animal Sciences
• /
• v.13 no.7
• /
• pp.913-917
• /
• 2000

Sixteen adult Barbari bucks were divided into 4 homogeneous groups, each group was offered wheat straw (WS) at levels 75, 100, 125 and 150 per cent of ad libitum intake in a factorial randomized complete block design. All goats were uniformly fed a supplement ($13.5g\;DM/kg\;W^{0.75}$) to fulfill their requirement for protein at maintenance level. The experimental feeding of goats at different levels for 21 days was followed by a digestion trial of 6 days and determination of rate of passage of digesta for 144 h duration, respectively. Intake ($g/kg\;W^{0.75}$) of dry matter (DM), organic matter (OM), digestible DM and digestible OM increased with increase in amount of WS offered. The levels of WS refusals for obtaining upper limit of intake was found to be above 30% of DMO. Concentration of ADF and lignin was significantly lower and CP was higher (p>0.05) in food ingested relative to food offered or refused in response to increasing allowance of WS. Dietary means of particulate rate of passage from rumen, transit time and total mean retention time ranged from 0.032 to 0.036/h, 19.10 to 21.72/h and 58.61 to 61.53/h respectively and did not show significant differences (p>0.05) irrespective of dietary level of WS. The results suggest that DMI and quality of ingested WS would improve with higher rates of offer and refusals (${\geq}30%$ of DMO) without any pronounced effect on passage kinetics of digesta, because of the greater opportunity afforded to goats for selective feeding.

• Asian-Australasian Journal of Animal Sciences
• /
• v.8 no.3
• /
• pp.267-273
• /
• 1995

The differences in rumen particle pool size, passage rate and rumen degradability in sheep receiving three varieties of orchardgrass hay harvested at pre-heading (H1), early-bloom (H2) and late-bloom (H3) were investigated using four ruminal-cannulated wethers (68 kg) fed 1,300 g of the hay once a day. Representative samples of whole rumen contents were collected at different times after feeding and the quantities of rumen particle pools [large particle pool (LPP), retained on a $1,180{\mu}m$ sieve; small particle pool (SPP), retained on a 47 but passed a $1,180{\mu}m$ sieve; and soluble fraction (SOL), passed a $47{\mu}m$ sieve (SOL)] were determined by a wet-sieving technique. The fullowing results were obtained: 1) The dry weight of whole rumen contents were significantly lower (p < 0.05) for HI than for H2 or H3. The reduction rate of whole rumen contents was slightly but significantly greater for HI that, the other hay varieties. 2) The LPP disappearance rates were 26.2, 25.3 and 21.7 g DM/h for H1, H2 and H3, respectively, and no statistical differences were found among the hay varieties. Appreciable changes were not observed with SPP and SOL throughout measurements for all hay varieties; however the SPP was markedly greater (p <0.05) for H2 and ill than for HI, while SOL did not differ among hay varieties. 3) The SPP passage rate (g DM/h) and effective rumen degradability (%) for HI, H2 and ill were, respectively, 9.7, 56.6; 16.9, 42.3; and 18.0, 28.9. The ruminal tum-over rate for SPP appeared to be higher for HI than for the other hay varieties.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.5
• /
• pp.449-456
• /
• 2010

The HCCI engine is a prospective internal combustion engine with which high diesel-like efficiencies and very low NOx and particulate emissions can be achieved. However, several technical issues must be resolved before HCCI engines can be used for different applications. One of the issues concerning the HCCI engine is that the operating range of this engine is limited by the rapid pressure rise caused by the release of excessive heat. This heat release is because of the self-accelerated combustion reaction occurring in the engine and the resulting engine knock in the high-load region. The purpose of this study is to evaluate the role of thermal stratification and fuel stratification in reducing the pressure rise rate in an HCCI engine. The concentrations of NOx and CO in the exhaust gas are also evaluated to confirm combustion completeness and NOx emission. The computation is carried out with the help of a multizone code, by using the information on the detailed chemical kinetics and the effect of thermal and fuel stratification on the onset of ignition and rate of combustion. The engine is fueled with dimethyl ether (DME), which allows heat release to occur in two stages, as opposed to methane, which allows for heat release in a single stage.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.6 no.6
• /
• pp.419-425
• /
• 2001

A dense pellicular solid matrix has been fabricated by coating 4% agarose gel on to dense zironia-silica(ZS) spheres by watr-in-oil emulsification . The agarose evenly laminated the ZS bead to a depth of 30㎛, and the resultin gpellicular assembly was characterised by densities up to 2.39g/mL and a mean particle dimeter of 136 ㎛. In comparative fluidisation tests, the pellicular solid phase exhibited a two-fold greater flow velocity than commercial benchmark ad-sorbents necessary to achieve common values of bed expansion. Furthermore, the perlicular parti-cles were characterised by improved qualities of chromatographic behaviour, particularly with re-spect to a three-fold increase in the apparent effective diffusivity of lysozyme within a pellicular assembly modified with Cibacron Blue 3GA. The properties of rapid protein adsorption/desorp-tion were attributed to the physical design and pellicular deployment of the reactive surface in the solid phase. When combined with enhanced feedstock throughput, such practical advantages recommend the pellicular assembly as a base matrix for the selective recovery of protein products from complex, particulate feedstocks(whole fermentation broths, cell disruptates and biological extracts).