• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.37 no.5
• /
• pp.879-890
• /
• 2017

The US Pavement Design method (AASHTO) and HDM-4, a road pavement maintenance decision system, are not suitable for domestic pavement design, construction and maintenance. KPRP(Korea Pavement Research Program) has been developed to reflect Korea's environmental conditions and vehicle characteristics, thereby, extending pavement life. The main objective of this study is to select the best alternative through Life Cycle Cost $CO_2$ (LCCC) calculations among three representative maintenance strategies using KPRP design software since the environment cost resulting from the extended pavement life will also differ. The analysis of this study illustrates that cumulative carbon emissions for 40 years in alternative 2 (Cutting and Overlaying at Year 30) is the lowest option among them, and the basic cost of $CO_2$ emission by various road maintenance and repair work can be used for suggesting an optimal maintenance strategy for highway agency.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.1
• /
• pp.65.1-65.1
• /
• 2016

We present results of long-term multi-wavelength polarization observations of the powerful blazar 3C 279 after its ${\gamma}$-ray flare on 2013 December 20. We followed up this flare by means of single-dish polarization observations with two 21-m telescopes of the Korean VLBI Network, carried out weekly from 2013 December 25 to January 11, and at 22, 43, and 86 GHz, simultaneously. These observations were part of the Monitoring Of GAmma-ray Bright AGNs (MOGABA) program. We Measured 3C 279 total flux densities at 22, 43, and 86 GHz, showing a mild variability of a factor of ${\leq}50%$ over the period of our observations. The spectral index ranged from -0.13 to -0.36 at between 22 and 86 GHz. The degree of linear polarization was in the range of 6 ~ 12 %, and slightly decreased with time at all frequencies. We found Faraday rotation measures (RM) of -300 to $-1200rad\;m^{-2}$ between 22 and 43 GHz, and -800 to $-5100rad\;m^{-2}$ between 43 and 86 GHz. The RM values follow a power law ${\mid}RM{\mid}{\propto}{\nu}^{\alpha}$, with a mean ${\alpha}$ of 2.2, implying that the polarized emission at these frequencies travels through a Faraday screen in or near the jet. We conclude that the regions emitting polarized radio emission may be different from the region responsible for the 2013 December ${\gamma}$-ray flare, and that these regions are maintained by the dominant magnetic field perpendicular to the direction of the radio jet at milliarcsecond scales.

• Journal of the Korean Institute of Gas
• /
• v.11 no.4
• /
• pp.17-22
• /
• 2007

The NOx emission characteristics with oxygen enrichment in non-premixed counterflow flames were investigated numerically. To consider systematically the situation of inevitable $N_2$ contamination by air infiltration in the process of pure-oxygen combustion, the volume ratio of $O_2$ in an oxidizer was changed from 21% to 100%. As a result the NO emission index $(EI_{NO})$ has the highest value under condition of 75% oxygen enrichment. This result can be explained by the change of $N_2$ destruction rate with oxygen enrichment rather than flame temperature, flame thickness and residence time. In particular, it was found that the reaction of N+NO=$N_2+O$ has the largest contribution on NOx production in oxygen-enrichment flames.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.4
• /
• pp.249-256
• /
• 2017

Premixed combustion has many advantages, including low CO and NOx emissions and a small combustor volume. These characteristics allow a compact design and wide application to condensing boilers with high thermal efficiencies. This study focused on the combustion characteristics in a premixed combustion burner using metal fiber and a throttle body. The results showed that a blue flame was found to be very stable at a heating load of 6,250-25,000 kcal/h when implementing the proper metal fiber, baffle plate, and throttle body. The NOx emission was less than 11 ppm under an equivalence ratio of 0.724-0.795, and the CO emission was less than 50 ppm under the same equivalence ratio. The thermal efficiency, which is a very important index when condensing a gas boiler, was observed to be above 96.3％ under an equivalence ratio of 0.750.

• Journal of Korean Society of Rural Planning
• /
• v.26 no.2
• /
• pp.61-70
• /
• 2020

The purpose of this study is to calculate the annual carbon reduction of crops according to the carbon fixation method of agricultural land, therefore to analyze whether the economic inducement of farmers to switch from single cropping to double cropping if the amount of carbon reduction were traded on the Korea Exchange. The analysis targets were Gyeonggi Province, which was divided into four areas to compare the difference between agricultural income and carbon income by crop and cropping system. Agricultural profit was estimated by multiplying the prior data of 2012 by the change rate of the consumer price index, and carbon income was calculated through the carbon reduction for each crop and the average transaction price of KAU19 traded on the Korea Exchange. According to the analysis, the profit rate of double cropping in all areas is -110.4% to 23% compared to single cropping, when only agricultural profit is taken into account, with no economic inducement for farmers to change the cropping system. However, when carbon income is taken into account together, the profit rate of double cropping rises significantly from 122.5% to 238.9% over a single operation in all areas, resulting in an economic inducement to switch the cropping system. This research is meaningful in that farming households could raise their income by additional carbon income, and that carbon credits could be supplied at Korea Exchange to further boost the carbon emission exchange.

• Journal of Climate Change Research
• /
• v.6 no.3
• /
• pp.193-201
• /
• 2015

The aim of this study is to find preferred climate condition for outdoor water activity and to estimate future change of preferred season for the activity following the climate change. We chose urban public swimming pools, Hangang park swimming pools, which do not have any attractions except pools and allow people to make decision to visit pools in the morning solely based on the weather conditions as study sites. We identified the preferred climate conditions by analyzing the relationship between number of visitors and temperature, wind chill temperature and discomfort indexes. According to the result, the preferred temperature range was from $23.51^{\circ}C$ to $37.56^{\circ}C$, the wind chill temperature range was from $25.90^{\circ}C$ to $39.43^{\circ}C$, the discomfort index range was from 71.61 to 88.98 and the precipitation range was below 22.8 mm per day. When the temperature range is applied as the preferred season, in present, the length of the season is 127 days, from end of May to end of September. However, if temperature increase resulting from lower emission scenario (RCP 6.0), the season would be extended to 162 days, from early May to middle of October. If temperature is increasing under high emission scenario (RCP 8.5), the length of the season would be extended to 173 days from early May to end of October. In addition, the period of between end of July and early August, which is currently the most preferred season, would not be favored anymore due to high temperature. The result of this study further suggests the necessity of climate change adaptation activities.

• Journal of the Microelectronics and Packaging Society
• /
• v.26 no.1
• /
• pp.23-28
• /
• 2019

The Titanium oxide ($TiO_2$) is an attractive ceramic material which shows non-toxic, high refractive index, catalytic activity and biocompatibility, and can be fabricated at a low cost due to its high chemical stability and large anisotropy. $TiO_2$ nanoparticles have been prepared by sol-gel method. The pH of solution can affect the $TiO_2$ crystallinity during the formation of nanoparticles. The prepared nanoparticles were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, photoluminescence spectroscopy in order to investigate their structural and photoluminescence properties. Through these analysis, the size of $TiO_2$ nanoparticles were found to be smaller than 5 nm. As the crystallinity of the nanoparticles increased, the emission of PL in the 550 nm region increased. Therefore, luminescence characteristics can be improved by controlling the crystallinity of the $TiO_2$ nanoparticles.

• Journal of Korean Society on Water Environment
• /
• v.38 no.2
• /
• pp.63-71
• /
• 2022

This study aimed to maximize the potential of fluorescence 3D excitation-emission matrix (EEM) for predicting the trihalomethane formation potential (THMFP) of DOM with various sources. Fluorescence spectroscopy is a useful tool for characterizing dissolved organic matter (DOM). In this study, differential spectroscopy was applied to EEM for the prediction of THMFP, in which the difference between the EEM before and after chlorination was taken into account to obtain the differential EEM (DEEM). For characterization of the original EEM or the DEEM, the maximum intensities of several different fluorescence regions in EEM, fluorescence EEM regional integration (FRI), and humification index (HIX) were calculated and used for the surrogates for THMFP prediction. After chlorination, the fluorescence intensity decreased by 77% to 93%. In leaf-derived and effluent DOM, there was a significant decrease in the protein-like peak, while a more pronounced decrease was observed in the humic-like peak of river DOM. In general, leaf-derived and effluent DOM exhibited a relatively lower THMFP than the river DOM. Our results were consistent with the high correlations between humic-like fluorescence and THMFP previously reported. In this study, HIX (r= 0.815, p<0.001), FRI region V (r=0.727, p<0.001), humic-like peak (r= 0.827, p<0.001) from DEEM presented very high correlations with THMF P. When the humic-like peak intensity was converted to a logarithmic scale, a higher correlation was obtained (r= 0.928, p<0.001). This finding suggests that the humic-like peak in DEEM can serve as a universal predictor for THM formation of DOM with various origins.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.252-252
• /
• 2022

Genotype-by-environment interaction (GEI) refers to the comparative response of genotypes to different environments conditions. Thus, understanding GEI is a fundamental component for selecting superior genotypes for breeding programs. The significance of utilizing early maturing cultivars not only provides flexibility in planting dates, but also serves as an effective strategy to reduce methane emission from the paddy fields. In this study, we conducted multi-environment trials (METs) to evaluate yield-related traits such as culm length, panicle length, panicle number, spikelet per plant, and thousand grain weight. A total of eighty-one Korean commercial rice cultivars categorized as early maturing cultivars, were cultivated in three regions, two planting seasons for two years. The genotype main effect plus genotype-by-environment interaction (GGE) biplot analysis of yield-related traits and grain yield explained 70.02-91.24% of genotype plus GEI variation, and exhibited various patterns of mega-environment delineation, discriminating ability, representativeness, and genotype rankings across the planting seasons and environments. Moreover, simultaneous selection using weighted average of absolute scores from the singular value decomposition (WAASB) and multi-trait stability index (MTSI) revealed six highly recommended genotypes with high stability and crop productivity. The winning genotypes under specific environment can be utilized as useful genetic materials to develop regional specialty cultivars, and recommended genotypes can be used as elite climate-resilient parents to improve yield-potential and reduce methane emission as part to accomplish carbon-neutrality.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.16 no.3
• /
• pp.181-188
• /
• 2013

The increase of carbon dioxide ($CO_2$) emission is known as one of the major causes of global warming, and it has a strong influence on the global environment. Therefore many researchers and politicians have tried to regulate the $CO_2$ emission. In regards to the matter, the IMPACT (Inclusive Marine Pressure Assesment and Classification Technology) committee under the Japan Society of Naval Architects and Ocean Engineers (JASNAOE) has developed an inclusive environmental impact assessment index, so-called "Triple I(III)", in order to assess the environmental impact including economic factors due to the artificial development of marine. In this study, III was applied to compare between the environmental impact of $CO_2$ emitted by container vessels during their life-cycle period and economic benefit due to their operating. Furthermore, III was also applied to assess the comprehensive environmental impact for the cases with various capacities of container vessels and different sailing route. From the results, the case for shortening of the sailing route is more effective to get the advantageous assessment results of III than the case for varying the size of vessels.