• Elastomers and Composites
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• 제56권4호
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• pp.243-249
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• 2021

The demand for truck bus radial (TBR) tires with enhanced fuel efficiency and wear resistance have grown in recent years. In addition, as the issue of particulate matter and air pollution increases, efforts are being made to reduce the generation of particulate matter. In this study, we investigated the effect of varying the content of butadiene rubber (BR) on the properties of the rubber compounds and the amount of particulate matter in the TBR tire tread compound. Furthermore, we utilized carbon black in the NR/BR blend compounds owing to its excellent compatibility, and we used silica in the ENR-25/BR blend compounds because it can interact chemically with epoxide groups. The NR/BR blend compounds and the ENR-25/BR blend compounds were evaluated by varying their BR content between 20 phr and 30 phr. The results showed that the ENR-25/BR blend compounds had superior wear resistance than the NR/BR blend compounds. This was caused by the interaction between silica and ENR. In addition, it was confirmed that the increased wear resistance as the BR content increased. Furthermore, compared to the NR/BR blend compounds, ENR-25/BR blend compounds exhibited a lower tan 𝛿 value at 60℃ because silica was used as filler. This indicates a higher fuel efficiency. The measurement results for wear particulate matter showed that as increasing the BR content resulted in generation of less wear particulate matter. This was caused by the increased wear resistance. Moreover, the ENR-25/BR blend compounds with excellent filler-rubber interaction exhibited lower quantities of generated wear particulate matters as compared to the NR/BR blend compounds.

• Elastomers and Composites
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• 제56권4호
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• pp.234-242
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• 2021

The demand for truck bus radial (TBR) tires with enhanced fuel efficiency and wear resistance have grown in recent years. In addition, as the issue of particulate matter and air pollution increases, efforts are being made to reduce the generation of particulate matter. In this study, the properties of epoxidized natural rubber (ENR) containing a silica-friendly functional group were evaluated by considering it as a base rubber and varying the silica ratio in this binary filler system. The results showed that the wear resistance of the NR/BR blend compound decreased as the silica ratio increased. In contrast, the ENR/BR blend compound exhibited an increase in wear resistance as the silica ratio was increased. In particular, the ENR-50/BR blend compound showed the best wear resistance due to the presence of several epoxide groups. Furthermore, we observed that for tan 𝛿 at 60℃, higher epoxide content resulted in the higher T_g of the rubber, indicating a higher tan 𝛿 at 60℃. On the other hand, it was confirmed that increasing the silica ratio decreased the value of tan 𝛿 at 60℃ in all compounds. In addition, we measured the amount of wear particulate matters generated from the compound wear. These measurements confirmed that in the binary filler system, regardless of the filler type, the quantity of the generated wear particulate matters as the filler-rubber interaction increased. In conclusion, the silica filled ENR/BR blend compound exhibited the lowest generation of wear particulate matters.

• 한국도시철도학회논문집
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• 제6권4호
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• pp.339-350
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• 2018

도시철도에서 지하 터널의 미세먼지는 여러 가지 요인에 의하여 발생하고 있다. 도시철도 미세먼지 발생량을 예측하기 위하여 여러 가지 발생요인 중 레일 마모량 분석에 관한 연구를 수행하였다. S호선 구간(약 45km)에서 1년 6개월 간 레일마모측정장치에서 측정된 레일 마모 데이터를 곡선반경(R)의 변화에 따라 약 170개 구간으로 구분하였으며, 레일 마모 측정값 중에서 직마모량(C0)와 편마모(V0)량을 이용하여 곡선반경에 따른 레일 마모량 관계를 분석하고, 직선구간과 곡선구간에서 각각 구간평균 편 직마모량과 노선평균 편 직마모량을 산출하였다. 레일 마모량과 레일 단면적의 상관관계를 분석하여 단면적에 대한 근사식을 구하고, 레일 C0와 V0의 변화량을 이용하여 레일 마모에 의한 미세먼지 발생량을 산정하였다.

• Elastomers and Composites
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• 제58권4호
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• pp.161-172
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• 2023

Because particulate matter has emerged as a major contributor to air pollution, the tire industry has conducted studies to reduce particulate matters from tires by improving tire performance. In this study, we compared the conventional blending method, in which rubber, filler, and additives are mixed simultaneously, to the Y-blending method, in which masterbatches are blended. We manufactured carbon black (CB)-filled natural rubber (NR)/butadiene rubber (BR) blend and silica-filled epoxidized NR/BR blend compounds to compare the effects of the two blending methods on the physical properties of the compounds and the amount of particulate matter generated. The Y-blending method provided uniform filler distribution in the heterogeneous rubber matrix, improved processability, and exhibited low rolling resistance. This method also improved physical properties owing to the excellent filler-rubber interaction. The results obtained from measuring the generation of particulate matter indicated that, the Y-blending method reduced PM_2.5 particulate matter generation from the CB-filled and silica-filled compounds by 38% and 60%, and that of PM₁₀ by 29% and 67%, respectively. This confirmed the excellence of the Y-blending method regarding the physical properties of truck bus radial tire tread compounds and reduced particulate matter generated.

• Tuberculosis and Respiratory Diseases
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• 제83권2호
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• pp.116-121
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• 2020

Particulate matter (PM) is suspended dust that has a diameter of <10 ㎛ and can be inhaled by humans and deposited in the lungs, particularly the alveoli. Recent studies have shown that PM has an adverse effect on respiratory diseases. The aim of this article is to review respiratory diseases associated with PM. According to existing studies, PM is associated with chronic obstructive pulmonary disease, bronchial asthma, and several other respiratory diseases and increases the mortality rates of these diseases. Moreover, increased exposure in the high concentration of atmospheric PM is associated with the development of lung cancer. The most simple and common way to protect an individual from airborne PM is to wear a face mask that filters out PM. In areas of high concentration PM, it is recommended to wear a face mask to minimize the exposure to PM. However, the use of N95 or KF94 masks can interfere with respiration in patients with chronic respiratory diseases who exhibit low pulmonary function, leading to an increased risk of respiratory failure. Conclusionally, reduction of the total amount of PM is considered to be important factor and strengthening the national warning notification system to vulnerable patients and proper early management of exacerbated patients will be needed in the future.

• 한국분말재료학회지
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• 제30권5호
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• pp.415-423
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• 2023

With the increasing attention to environmental pollution caused by particulate matter globally, the automotive industry has also become increasingly interested in particulate matter, especially particulate matter generated by automobile brake systems. Here, we designed a coating composition and analyzed its mechanical properties to reduce particulate matter generated by brake systems during braking of vehicles. We designed a composition to check the mechanical properties change by adding Cr₃C₂ and YSZ to the WC-Ni-Cr composite composition. Based on the designed composition, coating samples were manufactured, and the coating properties were analyzed by Vickers hardness and ball-on-disk tests. As a result of the experiments, we found that the hardness and friction coefficient of the coating increased as the amount of Cr₃C₂ added decreased. Furthermore, we found that the hardness of the coating layer decreased when YSZ was added at 20vol%, but the friction coefficient was higher than the composition with Cr₃C₂ addition.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1388-1398
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• 2011

Air pollution in subway tunnel is primarily caused from the wear of metallic materials. As undesirable substance, PM(Particulate Matter) can especially harm the health of passengers and workers as well as clog the main parts of rolling stock such as inverters. To improve the air quality in subway tunnel, SMRT(Seoul Metropolitan Rapid Transit Corporation) has developed anti-pollution devices such as Magnetic Dust Collector, Vacuum Cleaner For Rail Road and Particulate Removing Sprinkler Vehicle. Introducing these mechanical devices, this paper is mainly devoted to explaining the characteristics of collected dust according to the result of particle-size analysis and componential analysis.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.233-236
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• 2004

An experimental study was conducted to evaluate characteristic variation of diluted engine oil by diesel fuel and its effects on engine components. Especially, engine oil was made to have $15\%$ fuel content. To predict existing diesel fuel content in engine oil after test was used the viscosity calibration curve. About $54\%$ percent of diesel fuel in diluted engine oil was distillated by various paths related to reciprocating motion of piston and the rest diesel fuel plays an important role for decreasing engine oil viscosity. Test results show that lowered engine ell viscosity by diesel fuel dilution become a reason of increasing engine elements wear, Therefore, this caused the quantity of blow-by gas to increase and main gallery pressure to decrease.

• Environmental Engineering Research
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• 제19권4호
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• pp.331-338
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• 2014

Descriptive statistics methods were used to study the spatiotemporal variations and sources of ambient particulate matter ($PM_{10}$) in Luzhou, China. The analyzed datasets were collected from four national air quality monitoring stations: Jiushi (S1), Xiaoshi (S2), Zhongshan (S3), Lantian (S4) over the period of 2003-2012. This city was subjected serious $PM_{10}$ pollution, and the long-term annual average $PM_{10}$ concentrations varied from 76 to $136{\mu}g/m^3$. The maximum concentration was more than 3-fold of the annual average ($40{\mu}g/m^3$) issued by EPA-China for the ambient air quality. General temporal pattern was characterized by high concentrations in winter and low concentrations in summer, and general spatial gradient was in the reduction order of S2 > S4 > S3 > S1, which were both due to different particulate contributors and special meteorological conditions. The source apportionment indicated that vehicular emissions, road dusts, coal burning and chemical dusts were the major contributors of the identified $PM_{10}$ pollution, and the vehicular emissions and the road wear re-suspended particles dominated the heavy $PM_{10}$ pollution in recent years. Two other potential sources, agricultural and celebration activities could decrease the air quality in a short term. Finally, some corresponding suggestions and measures were provided to improve the air quality.

• Tribology and Lubricants
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• 제21권4호
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• pp.159-164
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• 2005

An experimental study was conducted to evaluate characteristic variation of diluted engine oils in which contains diesel fuels and its tribological effects on engine components. In this study, diluted engine oils with $10\%,\;15\%,\;and\;20\%$ of initial fuel content rate have been used for measuring the viscosity reduction rate, blow-by gas increment rate, main gallery pressure reduction rate, and fuel content rate in engine oils. These parameters are strongly related to the tribological characteristics of key engine components. The kinematic viscosity of engine oils in which is contained by diesel fuels from $10\%\;to\;20\%$ in oils is decreasing to approximately $54\%$ of initial diluted fuel-oil volume ratios. The experimental results show that the distillated engine oil decrease the viscosity of engine oil and its oil film stiffness, and increase the wear rate of rubbing parts of engine components. Thus we recommend that the containing volume rate of fuels in engine oils should be restricted to $3\~4\%$ for a sophisticated Diesel engine and $5\~7\%$ for a standard one.