• Journal of the Korean Society of Combustion
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• 제12권3호
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• pp.16-23
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• 2007

Employing an after-treatment system has almost become a mandatory requirement for Diesel vehicles, which results from a reinforced exhaust regulations as the number of vehicles powered by a Diesel engine increases. The Diesel Particulate Filter (DPF) system is considered as one of the most efficient method to reduce particulate matter (PM); however, the improvement of a regeneration performance at any engine operation point presents a considerable challenge by itself. Temperature, gas composition and flow rate of exhaust gas are important parameters in DPF evaluation processes, especially during a regeneration process. Engine dynamometer and segment tester are generally used in DPF evaluation so far. These test methods, however, could not completely evaluate the effect of various parameters on real DPF, such as oxygen concentration, amount of soot and exhaust gas temperatures. The evaluation of DPF systems using a dump combustor has been verified experimentally and this dump combustor system is likely to be appropriate for the DOC (Diesel Oxidation Catalyst) and SCR (Selective Catalytic Reduction) assessments test, too.

• Journal of The Korean Society of Agricultural Engineers
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• 제51권2호
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• pp.51-57
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• 2009

The purpose of this study was to investigate characteristics of behavior of nutrients such as TN (Total nitrogen), TDN (Total dissolved nitrogen), TP (Total phosphorus) TDP (Total dissolved phosphorous) in runoff water from a nonpoint source dominated watershed ($6.67\;km^2$). Regular and intensive flow measurement and water sampling were taken during two years (February 2002 to January 2004) in the Ingyeong River, a tributary of the Han River. The mean concentrations of nutrients during rainy days were significantly (p < 0.05) higher than those during dry days. The mean TDN/TN ratio in rainy days (95%) is almost identical to that in dry days (96%), but mean TDP/TP ratio in rainy days (24%) significantly decreased compared with that in dry days (66%), suggesting that dominant form of TP is shifted from dissolved form to particulate form. Accordingly, the measures (.eg. filter strips, cover crops) to reduce soil erosion for fallow upland in the rainy season should be taken to control particulate phosphorous.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제15권10호
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• pp.802-808
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• 2003

The air-side particulate fouling of the HVAC heat exchangers degrades the performance of cooling capacity, pressure drop across a heat exchanger, and indoor air quality. The purpose of this study is to investigate the fouling characteristics using accelerated particle loading system. The fouling characteristics are analyzed as functions of a dust concentration, a face velocity and a wet or dry surface condition. The pressure drop increases with increasing test operation and reaches constant asymptotic level. For the saturated condition due to particle loading, the pressure drop across the slitted finned-tube heat exchangers at the face velocity of 1 m/sec increases up to 57% and the cooling capacity decreases about 2%. The cooling capacities are not affected greatly by the presence of the fouling deposits if the thickness of the fouling deposits can not change substantially the flow pattern through the fins.

• Journal of Korean Society on Water Environment
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• 제27권4호
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• pp.397-404
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• 2011

This research investigates the runoff characteristics of refractory organic matters from Kyongan river watershed. Samples were taken 27 times during dry season, 4 times during rain events and analyzed into flow rate, Dissolved Organic Carbon (DOC), Particulate Organic Carbon (POC), Refractory Dissolved Organic Carbon (R-DOC), Refractory Particulate Organic Carbon (R-POC). R-DOC during dry season was the lowest in winter and showed a rising tendency in spring and R-POC changes less than R-DOC. The mass loading of Refractory Total Organic Carbon (R-TOC) in summer takes approximately 80% of 1 year mass loading. During rainy season, EMC of R-DOC was similar to R-DOC in dry season. But maximum EMC of R-POC was 12 times higher than that of R-POC in dry season. Results of the survey show that enhanced management of R-DOC in dry season and R-POC in rainy season is needed.

• Journal of Applied Biological Chemistry
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• 제64권1호
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• pp.1-4
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• 2021

Ambient air pollution, in particular, particulate matter (PM) pollution imposes serious health concerns such as hospitalization and premature deaths, worldwide. While commercial breathing masks are in use for protection against this hazardous issue, yet their efficiency in filtering PM was not up to the par, besides several other discomforts such as poor breathability due to reduced air flow, sweat production etc. In this study, commercial face mask coated with β-glucan, a high molecular weight polymer is tested for its efficacy in filtering PM. Quantification of PM before and after filtration and microscopic observation (using scanning electron microscopy (SEM)) of the fabric used in filtering the dust pollutants (generated from wood chips and cigarette) showed that β-glucan coated fabric were significantly efficient in capturing PM (size of 10 and 2.5 ㎛ in diameter) than that of the untreated control fabric, wherein the former had filtration efficacy with fold increase of 11.6 and 2.6 towards capturing PM2.5 and PM10 respectively than the latter. Thus, β-glucan coated fabric was found to be effective in filtering PM.

• Journal of Korean Society on Water Environment
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• 제26권2호
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• pp.332-342
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• 2010

A model has been developed to investigate in-river sediment and phosphorus dynamics. This advective-dispersive model is coupled with hydrodynamics and sediment transport submodels to simulate suspended sediment, total dissolved phosphorus, total phosphorus, and particulate phosphorus concentrations under unsteady flow conditions. It emphasizes sediment and phosphorus dynamics in unsteady flow conditions, in which the study differs from many previous solute transport studies, conducted in relatively steady flow conditions. The diffusion wave approaximation was employed for unsteady flow simulations. The first-order adsorption and linear adsorption isotherm model was used on the basis of the three-layered riverbed submodel with riverbed sediment exchange and erosion/deposition processes. Various numerical methods were tested to select a method that had minimal numerical dispersion under unsteady flow conditions. The responses of the model to the change of model parameter values were tested as well.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.369-372
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• 2008

An experimental study is carried out to study two-phase vertically upward hydraulic transport of solid particles by water in a vertical and inclined (0${\sim}$60 degree) concentric annulus with rotation of the inner cylinder. Rheology of particulate suspensions in shear-thinning fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, and so on. Annular fluid velocities varied from 0.2 m/s to 1.5 m/s for the actual drilling operational condition. Macroscopic behavior of solid particles, averaged flow rate, and particle rising velocity are observed. Main parameters considered in this study were radius ratio, inner-pipe rotary speed, fluid flow regime, and particle injection rate. For both water and CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become

• Clean Technology
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• 제25권2호
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• pp.153-160
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• 2019

As air pollution becomes more serious due to the increased number of diesel vessel operations, ship regulations on harmful emissions strengthen. Therefore, the development of a diesel exhaust after-treatment system for ships is required, and the higher the flow uniformity of the exhaust treatment system, the higher the treatment efficiency. With the computer software ANSYS Fluent, pressure drop and flow uniformity were used in this study to simulate flow rate with and without a baffle in both a Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) system. The system pressure drop was found to be 38 to 40 mbar in the existing system condition, and the flow uniformity was approximately 84 to 92% at the inlet and outlet of the DOC. When the baffle was installed inside the system, the pressure increased and the flow uniformity was lowered due to an increase in flow rate. When the exhaust gas flow was reduced by 50% from $7,548kg\;h^{-1}$ to $3,772kg\;h^{-1}$, the flow uniformity at the inlet and outlet of the DOC increased by approximately 1 to 3% due to the low flow rate. In the case of DPF, the flow uniformity of exhaust gas was 98 to 99% because the uneven flow proceeded after uniformly flowing from the DOC.

• Journal of computational fluids engineering
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• 제13권3호
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• pp.8-13
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• 2008

We present a numerical simulation technique and some preliminary results of the impact and spreading of a droplet containing particles on the solid substrate in 2D. We used the 2nd-order Adams-Bashforth / Crank-Nicholson method to solve the Navier-Stokes equation and employed the level-set method with the continuous surface stress for description of droplet spreading with interfacial tension. The impact velocity has been generated by the instantaneous gravity. The distributed Lagrangian-multipliers method has been combined for the implicit treatment of rigid particles and the discontinuous Galerkin method has been used for the stabilization of the interface advection equation. We investigated the droplet spreading by the inertial force and discussed effects of the presence of particles on the spreading behavior using an example problem. We observed reduced oscillation and spread for the particulate droplet.

• Transactions of the Korean Society of Automotive Engineers
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• 제5권1호
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• pp.1-13
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• 1997

The key point that guarantees the durability of the ceramic monolith filter is to lower peak temperature and temperature gradient inside filter during regeneration. The control of the exhaust gas flow rate into the filter, by the bypass technique of the exhaust gas, enables the gas temperature in filter to be constant for regeneration. A couple of methods, which are the ON/OFF and PID control of the bypass valve, were used for feedback control of the gas temperature. These techniques showed that the ceramic filter was regenerated perfectly under the peak temperature and peak temperature gradient limitations for durability.