• Journal of Korean Society of Transportation
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• v.30 no.5
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• pp.33-42
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• 2012

This study proposed a model for estimating the unit value of social cost for mobile emission considering local geographical and social characteristics, together with a method to evaluate the air quality value. The model was built based on benefit transfer methods, the population density, and green space ratio of each area, which are reflected through independent variables. While applying the model, the unit value of social cost for mobile emissions in both densely populated areas of Seoul and Busan was found to be 18.68 times and 10.71 times higher than the national average, respectively. It is highly expected that this study can contribute to providing more reliable guidelines to decision makers when evaluating various green transportation policies and projects.

• Journal of Wetlands Research
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• v.16 no.2
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• pp.281-291
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• 2014

In March to August 2013, the emission of gases ($CH_4$, VOC, $CO_2$, $O_2$, and LEL) was measured three times from the intertidal flat sediments at Sogeun-ri, Taean-gun, in the Mid-western seashore of Korea by using chamber method. After analyzing gas emission concentrations inside of flux enclosure chamber by using a GC equipped with Agilent 6890. The gas emission fluxes were calculated from a linear regression of the changes in the concentrations with time. The ranges of gas flux during the experimental period were $+0.06{\sim}+0.60mg/m^2/hr$ for $CH_4$, $+58.45{\sim}+95.58mg/m^2/hr$ for $CO_2$, $-0.02{\sim}-0.20mg/m^2/hr$ for $O_2$, and $-0.60{\sim}+0.65mg/m^2/hr$ for VOC, respectively. The flux measurement results revealed that $CH_4$ fluxes during March in the relatively low sediment temperature ($14.5^{\circ}C$) were significantly higher ($+0.60mg/m^2/hr$) than during June and August ($+0.06{\sim}+0.18mg/m^2/hr$) in high sediment temperature ($32.0{\sim}36.8^{\circ}C$). $CH_4$ flux to mean size of sediments and temperature of inner chamber exhibited strong positive correlation ($R^2=-0.97$ and $R^2=-0.89$, respectively).

• The Journal of the Korea Contents Association
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• v.10 no.9
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• pp.267-275
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• 2010

Quality management of an x-ray unit drastically differs according to the type of establishment of medical institutions. Many primary medical institutions have it, but they do not pay much attention to quality management. In the study, Gyeongbuk area has been divided into four zones from January 4, 2010 to September 3, 2010, and four places were designated by city. Among medical institutions located at a total of 16 sites, the target was 8 places with X-ray emission equipment 10 years or more in use as well as 8 places with X-ray emission equipment less than 10 years in use. The 5 essential items of quality control were tested. In the test that checked for equipment it was found that sites with X-ray emission equipment 10 years or more in use didn't have ground connection (6.25%) while all of them passed the current leak test. In the exposure dose reproducibility test 4 sites with X-ray emission equipment 10 years or more in use (25%) and 1 site with X-ray emission equipment less than 10 years in use didn't pass the test. In the KVp accuracy test 5 sites with X-ray emission equipment 10 years or more in use (31.25%) and 2 sites with X-ray emission equipment less than 10 years in use (12.5%) didn't pass the test. In the tube current and tube current amount test 3 sites with X-ray emission equipment 10 years or more in use (18.75%) and 1 site with less than 10 years in use (6.25%) didn't pass the test. According to the findings of the present research, quality control at medical institutions with X-ray equipment 10 years or more in use was poorer than medical institutions with X-ray equipment less than 10 years in use. In this regard, administrative and technical measures need to be taken as soon as possible. In addition, owners of medical clinics or unit managers need to raise awareness, and it is necessary to revise a regular test cycle every year or every two years if they have old equipment or if the equipment is not used on a frequent basis. And it is also important to provide regular educational programs for quality management.

• Environmental and Resource Economics Review
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• v.26 no.2
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• pp.205-227
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• 2017

Today, the global environment has so many serious problems such as global warming, ecological destruction and air pollution. Now China is the second largest carbon emissions country in the world. In this paper, we estimated the ratio of GDP per unit of carbon emissions for each of 30 provinces in China, and then also estimated the carbon emission efficiency of 30 provinces and analyzed the factors that affecting them. There are differences in carbon emission efficiency among different provinces, and carbon emission efficiency is relatively high in Hainan Province, Beijing, and Tianjin. In the regression results of the factors affecting the carbon emission efficiency, when the proportion of service industries is higher, the efficiency is higher. Also, when the higher the proportion of heavy industry and the higher the proportion of coal consumption are estimated to be worse.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.353-353
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• 2008

Carbon nanotubes (CNTs) are attractive for field emitter because of their outstanding electrical, mechanical, and chemical properties. Several applications using CNTs as field emitters have been demonstrated such as field emission display (FED), backlight unit (BLU), and X-ray source. In this study, we fabricated a CNT cathode using transparent ultra-thin CNT film. First, CNT aqueous solution was prepared by ultrasonically dispersing purified single-walled carbon nanotubes (SWCNTs) in deionized water with sodium dodecyl sulfate (SDS). To obtain the CNT film, the CNT solution in a milliliter or even several tens of micro-litters was deposited onto a porous alumina membrane through vacuum filtration process. Thereafter, the alumina membrane was solvated by the 3 M NaOH solution and the floating CNT film was easily transferred to an indium-tin-oxide (ITO) glass substrate of $0.5\times0.5cm^2$ with a film mask. The transmittance of as-prepared ultra-thin CNT films measured by UV-Vis spectrophotometer was 68~97%, depending on the amount of CNTs dispersed in an aqueous solution. Roller activation, which is a essential process to improve the field emission characteristics of CNT films, increased the UV-Vis transmittance up to 93~98%. This study presents SEM morphology of CNT emitters and their field emission properties according to the concentration of CNTs in an aqueous solutions. Since the ultra-thin CNT emitters prepared from the solutions show a high peak current density of field emission comparable to that of the paste-base CNT emitters and do not contain outgassing sources such as organic binders, they are considered to be very promising for small-size-but-high-end applications including X-ray sources and microwave power amplifiers.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.4
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• pp.234-244
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• 2014

Recently it has been focused that the automobile engine has developed in a strong upward tendency for the use of the high viscosity and poorer quality fuels in achieving the high performance, fuel economy, and emission reduction. Therefore it is not easy to solve the problems between low specific fuel consumption and exhaust emission control at motor cars. In this study, it is designed and used the engine test bed which is installed with turbocharger and intercooler. In addition to equipped using CRDI by controlling injection timing with mapping modulator, it has been tested and analyzed the engine performance, combustion characteristics, and exhaust emission as operating parameters, and they were engine speeds(rpm), injection timing(bTDC), and engine load(%). From the result of an experimental analysis, peak cylinder pressure and the rate of pressure rise were increased, and the location of it was closer toward top dead center according to the increasing of engine speed and load, and with advancing injection timing. The combustion characteristics are effected by fuel injection timing due to be enhanced the mass burned fraction. Using the engine dynamometer for analyzing the engine performance, the engine torque and power have been enhanced according to advancing the fuel injection timing. In analyzing of exhaust emission, there has been a trade-off between PM and NOx with increasing of engine speed and load, and with advanced injection timing. The experimental data are shown that the formation of NOx has increased and PM, vice versa.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.3
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• pp.337-351
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• 2006

In this study, to describe the basic characteristics of strong odorous sources, the emissions of odorous compounds from a large-scale sewage treatment plant in K city were investigated. According to this study, the emission patterns of major odorous compounds were distinguished clearly by several factors such as treatment processing types, chemical compositions of odors released, and temporal changes (e.g., seasonal variations). For the purpose of this study, emission rates of odorous compounds were quantified using a dynamic flux chamber (DFC) method from three major treatment (T) processes including T1 (Grit sedimentation basin), T2 (Aeration tank), and T3 (Final sedimentation). When the relative strengths of each emission source were compared, the strongest one was seen from T1 with the maximum of $NH_{3}\;(34.5\;{\mu}g/m^{2}/min)$ followed by $H_{2}S\;(20.4\;{\mu}g/m^{2}/min)($. While the strongest emissions of most odorous compounds were seen commonly from T1, those seen from T2 and T3 were significantly reduced relative to the ones found in T1. Considering the general patterns of odorous emission, it is concluded that control of odors from T1 unit is most important because of its considerably high emission strengths.

• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.5
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• pp.69-80
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• 2023

Carbon neutrality in agriculture can be derived from systematic GHG reduction policies based on quantitative environmental impact analysis of GHG-emitting activities. This study is to explore how to advance the calculation of carbon emissions from agricultural activities to the detailed spatial level to a spatial Tier 3 level (Tier 2.5 level), methodologically beyond the Tier 2 approach. To estimate the GHG emissions beyond the Tier 2.5 level by region for detailed spatial units, we constructed available activity data on carbon emission impact factors such as rice cultivation, agricultural land use, and livestock. We also built and verified detailed data on emission activities at the field level through field surveys. The GHG emissions were estimated by applying the latest national emission factors and regional emission factors according to the IPCC 2019 GL based on the field-level activity data. This study has significance that it explored ways to build activity data and calculate GHG emissions through statistical data and field surveys based on parcels, one of the smallest spatial units for regional carbon reduction strategies. It is expected that by utilizing the activity data surveyed for each field and the emission factor considering the activity characteristics, it will be possible to improve the accuracy of GHG emission calculation and quantitatively evaluate the effect of applying reduction policies.

• Journal of the Korea Concrete Institute
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• v.25 no.4
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• pp.365-370
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• 2013

In this study, contents of limestone in cement manufactured by six domestic plants for Portland cement were investigated in terms of the strength and its relation to the $CO_2$ emission due to limestone material and its physical properties in cement manufacturing process. the relationship among CaO content, compressive strength, and $CO_2$ emission was surveyed for the limestone quantity in decomposition reaction and the loss of limestone quantity contained in each cement. As a result of $CO_2$ emission calculation for unit cement, it was found that the $CO_2$ emission due to decomposition of limestone was occupied 67% of total emission quantity. Furthermore, there was a difference in $CO_2$ emission quantity depending on the cement manufacturing process management. Also, it was shown that fossil fuel usage and material loss had a major influence as main factors of $CO_2$ emission. An increase in the CaO content in cement resulted in an increase in the compressive strength. On the contrary, CaO content and compressive strength were reduced with the growth of loss quantity of limestone. It was verified that the material and process management were more effective than CaO yield in cement manufacturing for $CO_2$ emission with the growth of $CO_2$ emission quantity. Pozzolanic materials such as PFA and GGBS in concrete mix affected the price, $CO_2$ emission and development of strength of concrete.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.597-604
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• 2012

The present study assessed the $CO_2$ emissions of concrete according to the type and replacement ratio of supplementary cementitious materials (SCM) and concrete compressive strength using a comprehensive database including 2464 cement concrete specimens and 776 cement concrete mixes with different SCMs. The system studied in $CO_2$ assessment of concrete based on Korean lifecycle inventory was from cradle to pre-construction, which includes consistent materials, transportation and production phases. As the performance efficiency indicators, binder and $CO_2$ intensities were analyzed, and simple equations to evaluate the amount of $CO_2$ emission of concrete were then formulated as a function of concrete compressive strength and the replacement ratio of each SCM. Hence, the proposed equations are expected to be practical and useful as a guideline to determine the type and replacement ratio of SCM and unit content of binder in concrete mix design that can satisfy the target compressive strength and $CO_2$ reduction percentage relative to cement concrete.