• Korean Journal of Agricultural and Forest Meteorology
• /
• v.18 no.4
• /
• pp.337-347
• /
• 2016

Carbon dioxide ($CO_2$) and methane ($CH_4$) were measured in a rice-barley double cropping and rice mono cropping paddy fields, which are located in the southwestern coast of Korea, over a one-year period. Net ecosystems $CO_2$ exchange (NEE) and ecosystem respiration (Re) were estimated by the eddy covariance (EC) method, and an automatic open/close chamber (AOCC) method was used to measure $CH_4$ fluxes. Environmental factors (solar radiation, air temperature, precipitation etc.) were also measured along with fluxes. After the quality control and gap-filling, the observed fluxes were analyzed. As a result, NEE was -603.0 and $-471.5g\;C\;m^{-2}\;yr^{-1}$ in rice-barley double cropping and rice mono cropping paddy field, respectively. $CH_4$ emissions increased during the course of flooded days and were similar in two cropping paddy field. Accoding to rough results considering only fluxes of $CO_2$ and $CH_4$, it was estimated that the carbon absorbation in rice-barley double cropping paddy field was higher than that in rice mono cropping paddy field by $128.9g\;C\;m^{-2}\;yr^{-1}$.

• Korean Chemical Engineering Research
• /
• v.62 no.4
• /
• pp.312-326
• /
• 2024

This review comprehensively reviews the latest research trends in nickel catalysts for low-temperature CO₂ methanation reactions, with special emphasis on catalyst synthesis and reactor design for low-temperature CO₂ methanation reactions. In addition to the previously reported catalyst synthesis method of impregnation, the effects of structural and chemical properties of catalysts synthesized by solvothermal synthesis and electrospinning on CO₂ methanation reactions were analyzed. We also discuss the potential for process cost reduction and scale-up based on 3D catalyst structures and catalyst stacked reactor designs to improve reaction efficiency. It is found that the efficiency of the CO₂ methanation reaction can be maximized by controlling the oxygen vacancies and crystal structure of the catalyst through an innovative catalyst synthesis method, and by increasing the active area of nickel through the 3D structure of the catalyst and the reactor design. It is expected that this review will serve as the basis for the field of converting natural gas into CH₄, which can be used as a substitute for natural gas while reducing CO₂, a major greenhouse gas.

• Journal of Korean Society for Geospatial Information Science
• /
• v.18 no.3
• /
• pp.29-35
• /
• 2010

Soil organic carbon (SOC), being a help to forest formation and control of carbon dioxide in the air, is found to be an important factor by which global warming is influenced. Excavating the samples by whole area is very inefficient method to discovering the distribution of SOC. So, the development of suitable model for expecting the relative amount of the SOC makes better use of expecting the SOC. In the present study, a model based on a decision tree algorithm is introduced to estimate the amount of SOC along with accessing influencing factors such as altitude, aspect, slope and type of trees. The model was applied to a real site and validated by 10-fold cross validation using two softwares, See 5 and Weka. From the results given by See 5, it can be concluded that the amount of SOC in surface layers is highly related to the type of trees, while it is, in middle depth layers, dominated by both type of trees and altitude. The estimation accuracy was rated as 70.8% in surface layers and 64.7% in middle depth layers. A similar result was, in surface layers, given by Weka, but aspect was, in middle depth layers, found to be a meaningful factor along with types of trees and altitude. The estimation accuracy was rated as 68.87% and 60.65% in surface and middle depth layers. The introduced model is, from the tests, conceived to be useful to estimation of SOC amount and its application to SOC map production for wide areas.

• Journal of the Microelectronics and Packaging Society
• /
• v.31 no.2
• /
• pp.78-84
• /
• 2024

The electrochemical reduction of carbon dioxide (CO₂) is gaining attention as an effective method for converting CO₂ into high-value carbon compounds. This paper reports a facile meth od for synth esizing and characterizing g-C₃N₄-modified porous Au (pAu) electrodes for electrochemical CO₂ reduction using e-beam deposition and anodization techniques. The fabricated pAu@g-C₃N₄ electrode (@ -0.9 VRHE) demonstrated superior electrochemical performance compared to the pAu electrode. Both electrodes exhibited a Faradaic efficiency (FE) of 100% for CO production. The pAu@g-C₃N₄ electrode achieved a maximum CO production rate of 9.94 mg/s, which is up to 2.2 times higher than that of the pAu electrode. This study provides an economical and sustainable approach to addressing climate change caused by CO₂ emissions and significantly contributes to the development of electrodes for electrochemical CO₂ reduction.

• Journal of Environmental Science International
• /
• v.17 no.5
• /
• pp.501-507
• /
• 2008

The concentrations of HCHO(formaldehyde), $PM_{10}$(particulate matter), $CO_2$(carbon dioxide) and TBC(total bacteria counter) distribution in schools(Chung-Nam Area) were examined, and the results were compared with the recommended criterion of the administration law of indoor air. The subjects were an elementary school, a middle school and a high school in Chung-Nam area, and the concentration of TBC was examined by Single Stage Air Cascade Sampler, which applied the inertia collision catching method of 28.29L/min(flux) during 5 months from March, 2007 to July, 2007. The instrument(LD-3B, SIBATA Company)was used to examine $PM_{10}$, by a light scattering method and a light transmission method. The instrument(Airboxx(KD Engineering) was used to examine $CO_2$. The instrument(Z300XP(Environmental sensor)was used to examine HCHO. The result indicated that the $PM_{10}$ average concentrations of the surveyed classrooms were $49{\mu}g/m^3$ in Spring and $59{\mu}g/m^3$ in Summer. The $CO_2$ average concentration of the surveyed schools were 576 ppm in the classroom and 527 ppm in the stateroom. The average concentration of TBC were $729CFU/m^3$ in an elementary school, $401CFU/m^3$ in a middle school, $381CFU/m^3$ in a high school. The HCHO average concentration of the surveyed schools were 0.03 ppm in the classroom, 0.02 ppm in the stateroom.

• Ocean and Polar Research
• /
• v.27 no.2
• /
• pp.189-195
• /
• 2005

Several models predict large and potentially abrupt ocean circulation changes due to anthropogenic greenhouse-gas emissions. These circulation changes drive-in the models-considerable oceanic oxygen trend. A sound estimate of the observed oxygen trends can hence be a powerful tool to constrain predictions of future changes in oceanic deepwater formation, heat and carbon dioxide uptake. Estimating decadal scale oxygen trends is, however, a nontrivial task and previous studies have come to contradicting conclusions. One key potential problem is that changes in the historical observation network might introduce considerable errors. Here we estimate the likely magnitude of these errors for a subset of the available observations in the Southern Ocean. We test three common data analysis methods south of Australia and focus on the decadal-scale trends between the 1970's and the 1990's. Specifically, we estimate errors due to sparsely sampled observations using a known signal (the time invariant, temporally averaged, World Ocean Atlas 2001) as a negative control. The crossover analysis and the objective analysis methods are for less prone to spatial sampling location biases than the area averaging method. Subject to numerous caveats, we find that errors due to sparse sampling for the area averaging method are on the order of several micro-moles $kg^{-1}$. for the crossover and the objective analysis method, these errors are much smaller. For the analyzed example, the biases due to changes in the spatial design of the historical observation network are relatively small compared to the tends predicted by many model simulations. This raises the possibility to use historic oxygen trends to constrain model simulations, even in sparsely sampled ocean basins.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.3
• /
• pp.1016-1022
• /
• 2010

An Experimental study of cleaning solution has been performed on a high capacity steam boiler burning heavy fuel oil to on-line cleaning of deposit. The deposit is mixture of soot, slag, ash, metal oxide and clinker. The traditional technology of deposit cleaning was carried hand-crafted. The conventional technology of boiler cleaning method is mechanical removal by the worker while the boiler shut down operation. In this experiment, the deposit of mixture of soot, slag, ash, metal oxide and clinker has been removed by the cleaning agents without shut down of boiler burning. This study found out the optimum cleaning solution composition. The best results have been obtained when the mixture of ammonium nitrate and $MgNO_3$ were used in cleaning solution. The various transition metal effect was investigated for optimum mixing condition. In this research, the metal compound additive of the clean solution compoition was obtained. The combustion efficiency was improved by on-line cleaning with derived clean solution compoition. On-line cleaning method prevents the fouling and corrosion in the boiler and heat exchanger.

• Fire Science and Engineering
• /
• v.31 no.2
• /
• pp.37-43
• /
• 2017

The combustion characteristics of four kinds of wood specimens, such as Japan cedar, spruce, lauan, and red pine, were tested using the standards of Cone calorimeter (ISO 5660-1, 2) and smoke density tester (ASTM E 662). Japan cedar caught fire the quickest but the mean heat release rate was the lowest, $58.52kW/m^2$. The mean heat release rate of red pine appeared to be the highest, $71.75kW/m^2$. The lauan and Japan cedar generated relatively large amounts of carbon monoxide while the red pine and the spruce generated relatively large amounts of carbon dioxide. The red pine generated large amounts of smoke and the spruce generated the least amounts of smoke than the other samples. The total smoke release rate in the dynamic method was the highest in red pine and the lowest in spruce. The smoke density of red pine in the static method was highest in the non-flaming and flaming methods. In the non-flaming method, the smoke density of lauan was the second highest, whereas the flaming method was the least. In terms of the heat release rate, the fire risk from red pine was highest among the four test specimens. From the viewpoint of smoke generation, red pine was the most dangerous material in both dynamic and static methods.

• Journal of The Korean Association of Information Education
• /
• v.18 no.1
• /
• pp.89-100
• /
• 2014

While every nation in the world is emphasizing economic growth, we are confronting a side effect called environmental pollution. The main cause of environmental pollution is abuse of fossil fuels which emit carbon dioxide and are causing various problems including global worming. Green IT becomes popular as a method to reduce environmental pollution as well as a method to develop IT industry. The purpose of this paper is to develop education contents of green IT for elementary school students. For this purpose, extensive literature review works have been searched and analysed. In this paper, education contents of green IT are developed for three categories, knowledge, application, and ethics. In order to verify the validity of practical guidelines in application category, 55 elementary school teachers are randomly selected and their responses are gathered and analyzed through thorough statistical work. We expect that the proposed education contents will be guidelines for future green IT education.

• Journal of Energy Engineering
• /
• v.14 no.4 s.44
• /
• pp.219-225
• /
• 2005

for the removal of carbon dioxide in flue gas, which is the main cause of the global warming, chemical absorption methods were widely used for years. Alkanolamines such as MEA, AMP, MDEA are mainly used as an absorbent. In this study, cyclic amines - Piperazine, Piperidine and Cyclohelylamine are investigated to compare the chemical solubilities, absorption capacities and rate ot reaction. In conclusion, Piperazine is the most effective absorbent of $CO_2$ and ran be the excellent alternative to the former absorbents. Experiments were performed at 5, 10, 15 weight percent, 30, 40, $50^{\circ}C$, and the gas solubilities are determined by back-titration method, and using Gas Chromatography the absorption rate was compared.