• International conference on construction engineering and project management
• /
• 2022.06a
• /
• pp.952-959
• /
• 2022

Active construction work zones will result in longer travel time and/or longer travel distances for road users because of reduced speed limits and/or detours. This results in increased fuel consumption and increased emissions of harmful gases such as Carbon Monoxide (CO), Nitrogen Oxides (NOx), and Sulfur Oxides (SOx), which causes discomfort to the environment and road users around the work zone. The impact of such emissions should be considered while designing work zones or determining the number of days the roadway will be allowed to be closed partially or fully. This study develops a methodology to compute additional road user costs associated with such work zones. To achieve this goal, a) an extensive literature review is conducted, b) a framework to compute emission cost is developed, c) emission rates are computed for all counties (95) of the state of Tennessee, and d) a case study is conducted to demonstrate the use of the framework to estimate the additional impact of emission because of the work zone. For the case study conducted, the emission cost was computed to be $10,653.60 for the duration of the project. State DOTs can account for such road user costs while selecting contractors using A+B bidding. Accounting for such impact of emission will also indicate the agency's willingness to consider sustainability as a part of the business practices.

• Journal of Korean Society for Atmospheric Environment
• /
• v.29 no.6
• /
• pp.745-756
• /
• 2013

The purpose of this study is to evaluate representativeness of fuel-based emission factors. Twelve light-duty diesel vehicles which meet Euro-3 to 5 legislative emission limits were selected for emission tests. Second-by-second modal emission rates of vehicles were measured on a standard laboratory chassis dynamometer system. An off-cycle driving cycle was developed as a representative Korean real-world on-road driving cycle. Fuel-based emission factors were developed for short trip segments that involved in the selected driving cycle. Each segment was defined to have unit travel distance, which is 1 km, and characterized by its average speed and Relative Positive Acceleration (RPA). Fuel-based $NO_x$ emission factors demonstrate relatively good representativeness in terms of vehicle operation conditions. $NO_x$ emission factors are estimated to be within ${\pm}20%$ of area-wide emission factor under more than 40% of total driving situations. This result implies that the fuel-based $NO_x$ emission factor could be practically implemented into the on-road emission management strategies, such as a remote sensing device (RSD). High emitting vehicles as well as high emitting operating conditions heavily affect on the mean values and distributions of CO and THC emission factors. Few high emitting conditions are pulling up the mean value and biasing the distributions, which weaken representativeness of fuel-based CO and THC emission factors.

• 한국연소학회:학술대회논문집
• /
• 2004.11a
• /
• pp.187-194
• /
• 2004

The surface flames in porous ceramic burner are experimentally characterized to investigate the effects of equivalence ratio and firing rates. The results show that the surface flames are classified into green, red radiant and blue surface flame as the decrease of equivalence ratio. And each flame is maintained very stable and represents the same flame characteristics at any orientation of ceramic burner. Particularly the blue surface flame is found to be very stable at very lean equivalence ratio at 7000kcal/hr to 20000kcal/hr firing rates. And the exhausted NOx was analysed to find out which flame has lower NOx emission. The blue surface flame shows the lowest NOx emission regardless of the location of burner since it sustains very stable at lean mixture ratio.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.2
• /
• pp.29.4-29.4
• /
• 2016

The relations between star formation and properties of molecular clouds are studied based on a sample of star forming regions in the Galactic Plane. Sources were selected by having radio recombination lines to provide identification of associated molecular clouds and dense clumps. Radio continuum and mid-infrared emission were used to determine star formation rates, while 13CO and submillimeter dust continuum emission were used to obtain masses of molecular and dense gas, respectively. We test whether total molecular gas or dense gas provides the best predictor of star formation rate. We also test two specific theoretical models, one relying on the molecular mass divided by the free-fall time, the other using the free-fall time divided by the crossing time. Neither is supported by the data. The data are also compared to those from nearby star forming regions and extragalactic data. The star formation "efficiency," defined as star formation rate divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all the molecular gas.

• Publications of The Korean Astronomical Society
• /
• v.30 no.2
• /
• pp.511-512
• /
• 2015

Star formation activities dominate the evolution of galaxies. Elliptical galaxies are believed to be old galaxies in the Hubble sequence, and elliptical galaxies at different evolution epochs might have different star formation activities and/or morphologies. We investigate the connection between star formation rates and the morphology of elliptical galaxies. With the Sloan Digital Sky Survey (SDSS) and the Galaxy Zoo, we select a sample of elliptical galaxies by morphology and consider their infrared emission as an index of star formation rate to study the relation between the star formation rates and their morphological properties, such as ellipticities. In addition, we select some nearby spiral galaxies with very low MIR emission to probe the mechanisms of these red spiral galaxies. We display our preliminary results and discuss their implication on the evolution of galaxies in this poster.

• Analytical Science and Technology
• /
• v.28 no.3
• /
• pp.236-245
• /
• 2015

Recently, candles have been widely used to create a romantic atmosphere and to heat tea. In this study, a small combustion chamber for candle was designed using an 0.008 m³ bell jar. The emission factors of combustion products were then measured. The combustion chamber includes a glass dish, which prevents candle flame from affecting the composition of the gas emitted through the exhaust outlet. The outlet in the combustion chamber was designed as a cone shape, and it was lengthened to prevent flow from the outside, which could affect the homogeneous composition of the exhaust gas. The temperature at the outlet of the chamber was 34 ℃~41℃. The major combustion products of the candle, such as such aldehydes and acids, contained oxygen. The mass specific emission rates of benzene, toluene, ethylbenzene, and TVOC were 0.04 μg/g, 0.01 μg/g, 0.02 μg/g, and 3.81, respectively. The mass specific emission rates of formaldehyde, acetaldehyde and benzaldehyde were 4.48 μg/g, 1.09 μg/g, and 0.67 μg/g, respectively. Considering the different compositions of the candle samples, their mass specific emission rates were similar to those obtained by using a large chamber 0.17 m³~50 m³ in size.

• Journal of ILASS-Korea
• /
• v.17 no.3
• /
• pp.134-139
• /
• 2012

The main purpose of this study is to analyze and compare the nano-particle emission characteristics by 3-different biodiesel blending rates in a CI engine. Nano-particle number density emitted from various operating conditions of compression ignition engine can be investigated by using the PPS (Pegasor Particle Sensor) system. Namely, some particle charged through the corona discharge in real-time can be measured by PPS system. Under the steady state operation of the 2.0L CRDi diesel engine with different operating condition and biodiesel blending rates, the nano-particle number density was analyzed at the downstream position of DOC system. As this research result, more engine load speed and higher the concentration of biodiesel blending rate showed that the nano-particle number density decreases. Also we found that DOC system for clean diesel engine is effectively useful instrument to reduce diesel particulate matter as resource of nano-particle generation.

• Journal of ILASS-Korea
• /
• v.16 no.3
• /
• pp.146-151
• /
• 2011

LPG(Liquified Petroleum Gas) fuel for vehicles has lots of advantages such as low emission level, cheaper fuel cost and enough infrastructure. Therefore it arouses interest as an alternative engine to reduce emission of diesel engines. Especially MPI(Multi Point Injection) type LPLi(Liquid Phase LPG injection) system could have overcome the disadvantages of mixer types such as low engine performance, decreased charging efficiency and cold starting difficulty. However ice formation on the nozzle tip and intake port due to the freezing of moisture around the components is often observed in LPLi systems. This icing phenomenon is the direct cause of unstable engine combustion, resulting in engine emissions. Therefore in this research, a spray visualization test for LPG injection was carried out to obtain the basic information of an LPLi injector, then the effects of butane and propane mixing rates on ice formation at the intake port and nozzle tip was investigated. As a result, the icing characteristics of them showed contrary results according to the mixing rates.

• Nuclear Engineering and Technology
• /
• v.50 no.3
• /
• pp.446-452
• /
• 2018

To improve the accuracy and safety of irradiation tests in High flux Advanced Neutron Application ReactOr (HANARO), the nuclear energy deposition rate, which is called nuclear heating, was estimated for an irradiation capsule with an iridium sample in the irradiation hole in order. The gamma rays emitted from the radioisotopes (RIs) of the structural materials such as flow tubes of fuel assemblies and heavy water reflector tank were considered as radiation source. Using the ORIGEN2.1 code, emission rates of delayed gamma rays were calculated in consideration of the activation procedure for 8 years and 2 months of HANARO operation. Calculated emission rates were used as a source term of delayed gamma rays in the MCNP6 code. By using the MCNP code, the nuclear heating rates of the irradiation capsules in the inner core, outer core, and heavy water reflector tank were estimated. Calculated nuclear heating in the inner core, outer core, and heavy water reflector tank were 200-260 mW, 80-100 mW, and 10 mW, respectively.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2004.05a
• /
• pp.272-273
• /
• 2004