• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2208-2212
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• 2008

This paper deals with the cost reduction design of a single-phase line-start permanent magnet(LSPM) motor. Due to high cost of the permanent magnet(PM), cost reduction can be effectively achieved by reducing PM volume. Therefore, motor characteristics according to the PM volume are calculated by using d-q axis equivalent circuit analysis, and the characteristic map is made. In the characteristic map, maximum torque and efficiency are shown according to motor parameters such as back electromotive force(back emf) and inductances; back emf represents the PM volume. Minimum back emf and inductances satisfying output performance are determined in the characteristic map. Then, motor geometry based on the prototype motor is optimized to get the determined parameters using response surface methodology(RSM) and finite element method(FEM). Through the presented cost reduction design, total PM volume is reduced to 32% of prototype model.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.145-150
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• 2006

Recently emission regulation on diesel vehicles is getting stringent and research on aftertreatment technology such as DPF and DOC has been carried out actively. Even though PM(Particulate matters) reduction efficiency in DOC is relatively low but the structure is simpler and very effective in the reduction of gas materials and unregulated materials. Therefore it has been applied to smaller diesel vehicles. The aims of this research is to investigate the emission reduction characteristics of DOC; DOC performance of regulated and unregulated material emission reduction. It results a Pt based catalyst demonstrated higher emission reduction efficiency than a Pt-V based catalyst in CVS-75 mode, and also the reduction efficiency of unidentified material was excellent.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.176-180
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• 2013

After-treatment apparatus ceramic DPF (diesel particulate filter) have been applied to reduce harmful particulate matters(PM) among emissions from diesel engines so far, but they are easy to be fragile and weak in thermal shock. This research aims to investigate a metal type filter which is superior in mechanical strength and heat conduction rate and is beneficial economically in manufacturing. Basic performance of metal DPF such asloading test, temperature gradient test, thermal shock test, heat resistant test and back pressure was carried out. And then their experimental data provided key informations in designing and manufacturing such as detailed structures of metal mesh filter. Also diesel engine and vehicle of 2957cc displacement was tested under lug-down 3 mode and CVS-75 mode. PM reduction efficiency was 54.5% using metal DPF without loss of performance and fuel consumption.

• Journal of Environmental Health Sciences
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• v.49 no.6
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• pp.295-304
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• 2023

Background: Adolescents are relatively more sensitive than adults to exposure to indoor pollutants. The indoor air quality in classrooms where students spend time together must therefore be managed at a safe level because it can affect the health of students. Objectives: In this study, three types of green-wall models were applied to classrooms where students spend a long time in a limited space, and the resulting effects on reducing PM were evaluated. Methods: In the middle school classrooms which were selected as the experimental subjects, IoT-based indoor air quality monitoring equipment was installed for real-time monitoring. Three types of plant models (passive, active, and active+light) were installed in each classroom to evaluate the effects on improving indoor air quality. Results: The concentration of PM in the classroom is influenced by outdoor air quality, but repeated increases and decreases in concentration were observed due to the influence of students' activities. There was a PM reduction effect by applying the green-wall model. There was a difference in PM reduction efficiency depending on the type of green-wall model, and the reduction efficiency of the active model was higher than the passive model. Conclusions: The active green-wall model can be used as an efficient method of improving indoor air quality. Additionally, more research is needed to increase the efficiency of improving indoor air quality by setting conditions that can stimulate the growth of each type of plant.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.5
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• pp.411-417
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• 2002

The purpose of this study is to evaluate the emission reduction characteristics depending on the formation of the catalyst which influences the development of the diesel oxidation catalyst (DOC) suitable for small-sized diesel engines. We also attempted to suggest the feasibility of it as an after-treatment device. The reduction efficiency of DOC for CO and HC was proportional to the contents of precious metals, and the particulate matter (PM) has been reduced as much as 53∼59%. The reduction rate of soluble organic fraction (SOF) by DOC attachment revealed 100%. The composition of sulfate in PM increased from 3%, 7∼11% by installation of DOC. It is described that increase of sulfate contributed to the production of PM. This result also showed that the SOF and sulfate have trade-off relationship.

• Journal of ILASS-Korea
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• v.26 no.4
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• pp.163-170
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• 2021

Emergency generators normally use diesel engines. The generators need to conduct weekly no-load operation inspections to ensure stable performance at emergency situations. In particular, the generators with large diesel engines mainly use rectangle type filter substrates. In order to minimize hazardous emissions generated by generators, optimizing the reduction efficiency through CFD analysis of flow characteristics of PM/NO_X reduction system is important. In this study, we analyzed internal flow by CFD, which is difficult to confirm by experimental method. The main factors in our numerical study are the changes of flow uniformity and back pressure. Therefore, changes in flow characteristics were studied according to urea injector locations, selective catalyst reduction (SCR) diffuser angle, and filter porosity.

• Journal of Power System Engineering
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• v.12 no.5
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• pp.34-39
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• 2008

The combustion purpose of diesel engine is to reduce the emission of green gas and to produce high output. Generally, the regulation matter of emission gas is largely diveded by 'THC', 'NOx', 'CO' and 'PM'. Among those matters, the most problem is to disgorge into 'PM', the character of diesel combustion. Diesel PM can be controlled using Diesel Particulate Filter, which can effectively reduce the level of soot emissions to ambient background levels. $NO_2$ generated by the DOC is used to combust the carbon collected in the DPF at low temperature. To certificate DPF device that is suitable to domestic circumstances, it is necessary to exactly evaluate the DPF devices according to the regulation of DPF certificate test procedure fur retrofit. To do carry out the above-mentioned description the understanding of that regulation like the standard of PM reduction is needed. In this study the test procedure including test cycle and BPT test condition was examined, and also the test result for specific DPF was analyzed. In every test like field test, PM reduction efficiency test and Seoul-10 mode test, no defect was showed.

• Journal of Korean Society of Transportation
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• v.32 no.2
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• pp.93-105
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• 2014

This study evaluated the relative efficiency of mobile emission reduction countermeasures through a Data Envelopment Analysis (DEA) approach and determined the priority of countermeasures based on the efficiency. Ten countermeasures currently applied for reducing greenhouse gases and air pollution materials were selected to make a scenario for evaluation. The reduction volumes of four air pollution materials(CO, HC, NOX, PM) and three greenhouse gases($CO_2$, $CH_4$, $N_2O$) for the year 2027, which is the last target year, were calculated by utilizing both a travel demand forecasting model and variable composite emission factors with respect to future travel patterns. To estimate the relative effectiveness of reduction countermeasures, this study performed a super-efficiency analysis among the Data Envelopment Analysis models. It was found that expanding the participation in self car-free day program was the most superior reduction measurement with 1.879 efficiency points, followed by expansion of exclusive bus lanes and promotion of CNG hybrid bus diffusion. The results of this study do not represent the absolute data for prioritizing reduction countermeasures for mobile greenhouse gases and air pollution materials. However, in terms of presenting the direction for establishing reduction countermeasures, this study may contribute to policy selection for mobile emission reduction measures and the establishment of systematic mid- and long-term reduction measures.

• Journal of Environmental Health Sciences
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• v.36 no.4
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• pp.306-312
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• 2010

This field study was performed to evaluate the efficiency of a plasma ion-operated air cleaner in temporal reduction of airborne pollutants emitted from a pig housing facility. In the case of gaseous pollutants, the plasma ion air cleaner was not effective in reducing levels of ammonia, hydrogen sulfide, nitrogen dioxide, or sulfur dioxide (p>0.05). In the case of particulate pollutants, however, the air cleaner was effective in reducing levels of particulate matter ($PM_{2.5}$ and $PM_1$) by 79(${\pm}6.1$) and 78(${\pm}3.0$)%, respectively. Unlike the case of these fine particle fractions, the reduction of total suspended particles (TSP) and $PM_{10}$ following treatment was almost negligible. In the case of biological pollutants, the mean reduction efficiencies for airborne bacteria and fungi were relatively low at 22(${\pm}6.6$) and 25(${\pm}8.7$)%, respectively. Taken together, these results indicate that in terms of air pollutants released from this pig housing facility, the plasma ion air cleaner was primarily effective in reducing levels of $PM_{2.5}$ and $PM_1$.

• Journal of People, Plants, and Environment
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• v.23 no.6
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• pp.637-646
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• 2020

Background and objective: The main objective of this study is to measure the amount of particulate matter (PM) reduction under different characteristics of leaves in 18 different species of indoor plants. Methods: First, a particular amount of PM was added to the glass chambers (0.9×0.86×1.3 m) containing the indoor plant (height = 40 ± 20 cm), and the PM concentration were measured at 2-hour intervals. The experiment with the same conditions was conducted in the empty chamber as the control plot. Results: The range of PM reduction per unit leaf area of 18 species of experimental plants was 3.3-286.2 ㎍·m^-2 leaf, total leaf area was 1,123-4,270 cm², and leaf thickness was 0.14-0.80 mm and leaf size 2.27-234.47 cm². As time passed, the concentration of PM decreased more in the chamber with plants than in the empty chamber. Among the 18 indoor plants, the ones with the greatest reduction in PM2.5 in 2 hours and 4 hours of exposure to PM2.5 were Pachira aquatica and Dieffenbachia amoena. As the exposure time of PM increased, the efficiency of reducing PM2.5 was higher in plants with medium-sized leaves than plants with large or small leaves. The effect of reducing PM2.5 was higher in linear leaves than round or lobed leaves. Plants with high total leaf area did not have advantage in reducing PM because the leaves were relatively small and there were many overlapping parts between leaves. In the correlation between leaf characteristics and PM 2.5 reductions, all leaf area and leaf thickness showed a negative and leaf size showed a positive correlation with PM reduction. Conclusion: The PM reduction effect of plants with medium-sized leaves and long linear leaves was relatively high. Moreover, plants with a large total leaf area without overlapping leaves will have advantaged in reducing PM. Plants are effective in reducing PM, and leaf characteristics are an important factor that affects PM reduction.