• Ocean and Polar Research
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• v.27 no.2
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• pp.189-195
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• 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 Korean Society for Atmospheric Environment
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• v.30 no.5
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• pp.423-433
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• 2014

This study examined the short-term variability of $CO_2$ concentrations measured at the Gosan site ($33^{\circ}17^{\prime}N$, $126^{\circ}10^{\prime}E$) in Jeju, Korea for the last 9 years from 2002 to 2010. The weekly distribution shows higher $CO_2$ concentrations during weekends than weekdays which implies the impact of local emissions because Jeju Island is one of the top tourist attraction in Korea. In diurnal variation, $CO_2$ concentration reached the maximum at 6 am and the minimum at 1 pm. The high $CO_2$ concentrations were mostly associated with lower wind speed (below 4 m/s) and easterlies, which was typical of summer night. In other seasons, however, the high concentrations were encountered under strong westerlies (8~16 m/s), which implies the influence of Chinese outflows. $CO_2$ concentrations were found to be highly correlated with meteorological parameters including wind speed, temperature, humidity, and solar radiation except for winter.

• Journal of Environmental Science International
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• v.29 no.7
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• pp.729-737
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• 2020

This study estimates the greenhouse gas (GHG) emissions reduction resulting from photovoltaic and wind power technologies using a bottom-up approach for an indirect emission source (scope 2) in South Korea. To estimate GHG reductions from photovoltaic and wind power activities under standard operating conditions, methodologies are derived from the 2006 IPCC guidelines for national GHG inventories and the guidelines for local government greenhouse inventories of Korea published in 2016. Indirect emission factors for electricity are obtained from the 2011 Korea Power Exchange. The total annual GHG reduction from photovoltaic power (23,000 tons CO_2eq) and wind power (30,000 tons CO_2eq) was estimated to be 53,000 tons CO_2eq. The estimation of individual GHGs showed that the largest component is carbon dioxide, accounting for up to 99% of the total GHG. The results of estimation from photovoltaic and wind power were 63.60% and 80.22% of installed capacity, respectively. The annual average GHG reductions from photovoltaic and wind power per year per unit installed capacity (MW) were estimated as 549 tons CO_2eq/yr·MW and 647 tons CO_2eq/yr·MW, respectively. Finally, the results showed that the level of GHG reduction per year per installed capacity of photovoltaic and wind power is 62% and 42% compared to the CDM project, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.68-78
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• 2006

In the past few years, considerable efforts have been directed towards the further development of Urea-SCR(selective catalytic reduction) technique for diesel-driven vehicle. Although urea possesses considerable advantages over Ammonia$(NH_3)$ in terms of toxicity and handling, its necessary decomposition into Ammonia and carbon dioxide complicates the DeNOx process. Moreover, a mobile SCR system has only a short distance between engine exhaust and the catalyst entrance. Hence, this leads to not enough residence times of urea, and therefore evaporation and thermolysis cannot be completed at the catalyst entrance. This may cause high secondary emissions of Ammonia and isocyanic acid from the reducing agent and also leads to the fact that a considerable section of the catalyst may be misused for the purely thermal steps of water evaporation and thermolysis of urea. Hence the key factor to implementation of SCR technology on automobile is fast thermolysis, good mixing of Ammonia and gas, and reducing Ammonia slip. In this context, this study performs three-dimensional numerical simulation of urea injection of heavy-duty diesel engine under various injection pressure, injector locations and number of injector hole. This study employs Eulerian-Lagrangian approach to consider break-up, evaporation and heat and mass-transfer between droplet and exhaust gas with considering thermolysis and the turbulence dispersion effect of droplet. The SCR-monolith brick has been treated as porous medium. The effect of location and number of hole of urea injector on the uniformity of Ammonia concentration distribution and the amount of water at the entrance of SCR-monolith has been examined in detail under various injection pressures. The present results show useful guidelines for the optimum design of urea injector for reducing Ammonia slip and improving DeNOx performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.134-141
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• 2017

Many studies have been conducted with respect to the materials to replace the cement in order to reduce the carbon dioxide emissions during the cement production. Activated hwangtoh as cement replacement material goes through calcination process of $850^{\circ}C$. PVA fibers and GFRP bars are used in order to compensate for the cracks of activated hwangtoh concrete(AHC). This paper presents an experimental study investigating the bond characteristic of GFRP bars in PVA fiber reinforced AHC under tensile loads. Experimental results showed that average bond strength factor of specimens with and without PVA fiber was 2.27~2.48 and was not significantly affected by the ratio of PVA fiber andactivated hwangtoh. In addition, as the bond length was increased, the bond strength was reduced.

• Journal of Adhesion and Interface
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• v.20 no.4
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• pp.140-145
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• 2019

In view of environmental considerations, the control of carbon dioxide (CO₂) and volatile organic compounds (VOCs) is one of important issues in the film and coating industries. Therefore, UV-curable system has been developed due to minimize emissions of VOCs and reduce CO₂ emission due to low energy consumption from fast curing. Also, biodegradable polymers economically are attractive because of environmental and economic concerns associated with huge waste plastics. In this study, UV-curable polyurethane acrylates with different compositions of biodegradable polylactide (PLA) diol and poly(ethylene glycol) as diols were synthesized and curing reaction of their end-capped acrylates was performed by UV exposure. Tensile strength, elongation, and Tg of the UV-cured polyurethane acrylates increased with PLA diol content in the diol while their hydrophilicity and thermal stability increased with the PEG content. These results indicated a property of UV-cured polyurethane acrylates could be controlled by environment-friendly diols.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.2
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• pp.135-140
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• 2011

Currently, studies have show that the network related energy consumption are increasing. and part of overall energy consumption of our society are too. So, that is important to look for energy-efficient network applications and protocols. A most of network energy consumption are due to network edge devices. in this paper, in order to cut down the emissions of carbon dioxide from ICT business, which contributes 2% of the global energy consumption, it is necessary to understand energy consumption in peer-to-peer system. In this paper, in this paper we propose a architecture based on the introduction of a p2p proxy. The model is analyzed analytically and numerically to reveal how these factors influence the overall power consumption in both steady state and flash crowd information exchange scenarios. Specifically, our results show that the proxy-based solution can provide up to 50% reduction in the energy consumption and, at the same time, a significant reduction in the average file download time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.338-343
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• 2017

In this study, blast furnace slag powder was used in concrete to help reduce carbon dioxide emissions and to recycle industrial waste. Blast furnace slag powder is a byproduct of smelting pig iron and is obtained by rapidly cooling molten high-temperature blast furnace slag. The powder has been used as an admixture for cement and concrete because of its high reactivity. Using fine blast furnace slag powders in concrete can reduce hydration heat, suppress temperature increases, improve long-term strength, improve durability by increasing watertightness, and inhibit corrosion of reinforcing bars by limiting chloride ion penetration. However, it has not been used much due to its low compressive strength at an early age. Therefore, this study evaluates the effects of steam curing for increasing the initial strength development of concrete made using slag powder. The relationship between compressive strength, SEM observations, and XRD measurements was also investigated. The concrete made with 30% powder showed the best performance. The steam curing seems to affect the compressive strength by destroying the coating on the powder and by producing hydrates such as ettringite and Calcium-Silicate-Hydrate gel.

• KIEAE Journal
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• v.7 no.5
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• pp.93-98
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• 2007

Effort has been performed for latest 20 years to improve resident's comfort and indoor environment in building. And interest and effort to improve indoor air environment among various indoor environment elements have continuously increased since 1990s, because it is examined scientifically that various contaminants generated indoor affect human body. Specially, indoor air contaminants generated from apartments are those exhausted from resident's indoor environment, closing materials and household. Indoor air environment in buildings is different according to pollution degree, existence availability of pollution source, ventilation amount, and meteorology. It is known that other contaminants more than about 900 kinds generate according to a kind of work or action in a room. Specially, nowadays buildings are well insulated and confidentiality-centered for environment protection and economical side. So indoor air contaminants are generated from indoor air pollution sauces of unprepared ventilation, human body carbon dioxide emissions, and various building materials. when these are accumulated in long term human body, it is harmful to resident's health, but awareness for this is very insufficient. Because bedroom is space that people inhabit for a long time by unconscious state and indoor environment occupies important part for resident's health and quality of life at sleep, the actual condition of air quality is investigated, improvement countermeasure is considered, and ventilation amount is analyzed. In this study, putting case that the most longest stayed time is sleeping time when people inhabit in the apartment, the air quality according to volume of bedroom space at sleep was measured and analyzed, and the data acquired will be the basis for improvement on this.

• Resources Recycling
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• v.20 no.2
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• pp.3-15
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• 2011

Current, Registration fields of CDM projects are being conducted in a variety of parts such as mostly energy, chemical processing and manufacturing processes. However, there are not many CDM project registrations by recycling of inorganic waste. In this paper, analysis abroad CDM project and applications in order to review possibility of CDM project registration through the recycling of domestic inorganic waste were investigated. As a results, registered case of CDM project by inorganic waste recycling was researched to registrate in raw material alternative field of cement industry that inorganic waste can be used in large quantities. Application prospects of CDM project in Korea will be possible to analysis industrial scale, industry using inorganic raw materials, green house gas emissions and inorganic waste generated in large quantities.