• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.8
• /
• pp.547-553
• /
• 2013

This paper investigates the effect of coal-fired fly ash on dry $CO_2$ sorbents as the supports and additives. For this purpose, various kinds of dry sorbent were manufactured by mixing fly-ash, the primary $CO_2$ absorption components (NaOH and CaO) and water with their different combination. Thereafter, their $CO_2$ absorption performance and the property were analyzed. As a result, variation of absorption efficiency and temperature as well as $CO_2$ desorption of the sorbents are confirmed, which may be primarily ascribed to fly-ash addition to the sorbents. Particularly, fly-ash effect is strongly measured in the sorbent manufactured by mixing all four components (named WNCF sorbents). Absorption efficiency of WNCF sorbents at $550^{\circ}C$ is 35.6% higher than that of flyash free sorbent and desorption is solely observed in WNCF sorbents. Fly-ash in WNCF sorbents leads to increase the dispersity of $CO_2$ absorption components and decrease their particle size in the sorbents. In addition, fly-ash is used as the supports and pozzolanic reaction is hindered by NaOH in WNCF sorbent. Furthermore, $CO_2$ desorption from the sorbents may be due to fly-ash. The interaction between fly-ash and $CO_2$ absorption components substantially attenuate the strength between captured $CO_2$ in CaO and NaOH.

• Journal of the Korea Society for Simulation
• /
• v.24 no.1
• /
• pp.35-43
• /
• 2015

This research proposed a new method to evaluate the objective validity to launch smart transportation services that various stakeholders are complicatedly inter-connected. First of all, we have designed the fundamental business model to form the smart transportation services and defined the stakeholders taking part in the services. Also, the criteria to evaluate the economical validity has been proposed based on the relationship among stakeholders. Especially, in the case EV drivers and charging service providers, the economical validity depends on the scale of spreading. Therefore, we have compared the two extreme scenarios, the poor and stable level of EV spreading. According to the result, it may be said that EV drivers and charging service providers cannot be guaranteed the economical validity due to the burden of initial investment. On the contrary to this, suppliers of EV and charging gears may secure more than a certain level of profit. In addition, the government may have great profit due to reducing the CO2 emission and cost for importing energy sources. Therefore, it is needed to enhance the level of supporting EV drivers and charging service providers at the first stage. Also, the impact of the ratio of EV and charging service stations on the economical validity of smart transportation should be further investigated.

• Composites Research
• /
• v.28 no.4
• /
• pp.219-225
• /
• 2015

Air spoiler, which can reduce the drag during operation, can be considered as a possible means to reduce carbon dioxide emission and to increase fuel efficiency. In this study, a composite air spoiler was designed and tested by static and repeated loads. The Green Water Pressure of 0.1 MPa a ship experiences during operation was perpendicularly applied to the air spoiler. Air spoiler was manufactured with sandwich panel which has glass fabric face and balsa core. Multiple sandwich panels were assembled to steel frame by bolt joint. The joint was designed to have bearing failure and examined by static and fatigue tests. Tests showed that the designed joint has enough margin of safety to endure joint failure. The developed sandwich panel to air spoiler is planned to be applied to a large scale commercial ship.

• Journal of the Korea Concrete Institute
• /
• v.24 no.3
• /
• pp.315-322
• /
• 2012

Alkali-activated slag (AAS) is the most obvious alternative materials that can replace OPC. But, AAS industrial usage as a structural material should be evaluated for its durability. Carbonation resistance is one of the most important factors in durability evaluation. Test results for 18 slag-based mortars activated by sodium silicate and 6 OPC mortars were obtained in this study to verify the carbonation property. Main variables considered in the study were flow, compressive strength before and after carbonation, and carbonation depth. Mineralogical and micro-structural analysis of OPC and AAS specimens prior to and after carbonation was conducted using XRD, TGA, FTIR FE-SEM. Test results showed that CHS was major hydration products of AAS and, unlike OPC, no other hydration products were found. After carbonation, CSH of hydration product in AAS turned into an amorphous silica gel, and alumina compounds was not detected. From the analysis of the results, it was estimated that the micro-structures of CSH in AAS easily collapsed during carbonation. Also, the results showed that this collapse of chemical chain of CSH lowered the compressive strength of concrete after carbonation. By increasing the dosage of activators, carbonation resistance and compressive strength were effectively improved.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.6 no.1
• /
• pp.63-71
• /
• 2011

Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. In this study, we investigated the influence of alkali activator and superplasticizer on the flowability and compressive strength of the alkali-activated mortar in oder to develop cementless alkali-activated concrete using blast furnace slag. In view of the results, we found out that the type and mixture ratio of alkali activator, the type and adding order of superplasticizer results to be significant factors. When cementless alkali-activated mortar using blast furnace slag manufactured with 1:1 the mass ratio of 9M NaOH and sodium silicate, and added superplasticizer before alkali activator in the mixer, we can be secured workability with 180 mm of flow during 1 hours and compressive strength of about 50 MPa under $20^{\circ}C$ curing condition at age of 28days.

• Resources Recycling
• /
• v.24 no.2
• /
• pp.13-22
• /
• 2015

$CO_2$ emitted from building materials and construction materials industry reaches about 67 million tons, which occupy about 30 % of $CO_2$ emitted from the construction field. Controls on the use of consumed fossil fuels and reduction of emission gases are essential for the reduction of $CO_2$ in the construction area as we reduce the second and third curing to emit $CO_2$ in the construction materials industry. Accordingly, this study applied the low energy curing admixture (hereinafter "LA") to the extruded panels to observe the physical properties, depending on the mixing amount of fiber, type of fiber and mixing ratio of fiber. The type of fiber did not appear to be a main factor to affect strength, while the LA mixing ratio and mixing amount of fiber appeared to be major factors to affect strength. Especially, the highest strength was developed when the LA mixing ratio was 40%, whereas the test object with the mixing ratio of 50% resulted in the decrease of strength. In addition, it appeared that the mixing ratio of fiber greatly affected flexural strength and strength increased as the mixing ratio increased.

• Clean Technology
• /
• v.18 no.1
• /
• pp.69-75
• /
• 2012

In this study, we executed an environmental impact assessment about recycling of ITO (Indium Tin Oxide), used for touch panel. ITO is mainly used to make transparent conductive coatings for touch and flat screen LCD (Liquid Crystal Display), ELD (Emitting Light Device), PDP (Plasma Display Panel). This demand is increasing little by little. but form current status, ITO is discarded than recycling. It is important to recycling ITO for national strategies about resource conservation, and reduce environmental burden. Also Landfill or incineration of ITO cloud be harmful to the human health in the long-term. Material Life Cycle Assessment method (MLCA) was conducted for comparison landfill and recycling of ITO. MLCA would provide more information for environmental issues and potential environmental impacts of ITO. The study includes two scenarios, the basic scenario is recycling of ITO (10, 20, 30%) and the other scenario is landfill of ITO. In addition, amount of carbon dioxide and energy were calculated.

• Plant Journal
• /
• v.10 no.2
• /
• pp.28-37
• /
• 2014

Recently, it is considered that environment and energy are critical issues all over the world. In power generation sector in Korea, almost power stations are constructed and operated as cogeneration plants in conformity with this trend. KDHC(Korea District Heating Corporation) goes one step further adopting renewable energy technology like heat pump using wasted heat for energy-saving and environment improvement. This study investigates the performance characteristics by the location of waste heat recovery heat pumps of 5 Gcal/h capacity in 150 MW-class Gwang-gyo cogeneration plant using commercial software 'THERMOFLEX'. Prior to analysis, the simulations are performed with actual operation data, and then the validation of simulations is verified by checking the error within 2%. After verification, the simulations are carried out with 3 locations and the effect on electrical power output and heat output is analyzed. As a result, overall efficiency of cogeneration plant is the highest in the case of heat pump located before DH(District Heating) Heater because of the largest increase of heat output despite of decrease of electrical power output.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.18 no.4
• /
• pp.274-286
• /
• 2016

Carbon dioxide ($CO_2$) accounts for about 72% of the total greenhouse gas emissions. It is also widely known as a major cause of global warming. According to the IPCC's fifth evaluation report, the growth rate of atmospheric $CO_2$ has increased by 35% for the last 100 years and global warming is occurring much more rapidly than expected since 1990s. As a result of climate change, global warming is increasing the frequency and severity of extreme weather events around the world, which has changed forest vegetation zone and vegetation phenology. The Kyoto Protocol recognizes the importance of forests and refers to the conservation and enhancement of forests as sinks and reservoirs of greenhouse gases. In this regard, studies of tree responses to climate change are indispensable for predicting changes in the forest ecosystems in the future. Therefore, studies using long-term climate change research facilities, associated with long-term ecological research (LTER) in the fields, will make a considerable contribution to predict and approach the changes in the future.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.2
• /
• pp.219-226
• /
• 2020

Over the last decades, great efforts have been devoted to reuse industrial wastes and by-products from various industries as supplementary cementitious materials in order to reduce carbon dioxide(CO₂) emission by reducing the use of Portland cement in construction. Oyster shell waste, originating from the fishery industry, is available in huge quantities in certain areas, and is generally discarded or landfilled. In this study, we aimed to reuse oyster shell as an alternative to limestone in limestone calcined clay cement(LC³). The oyster shell calcined clay cement(OC³) paste were produced and were characterized via X-ray diffraction, isothermal calorimetry, compressive strength tests, and thermogravimetry. The results revealed that OC³ pastes exhibited similar strength development and reactivities by pozzolanic reaction with LC³, which implies that oyster shell could be used as a substitute for limestone in LC³.