• Transactions of the Korean hydrogen and new energy society
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• v.21 no.5
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• pp.355-363
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• 2010

High purity hydrogen, 97-99 vol.%, with CO at just ppm levels was obtained in a fixed bed of iron oxide employing the steam-iron cycle operation with reduction at 823K and oxidation in a steam-$N_2$ mixture at 773K TGA experiments indicated that temperature of the reduction step as well as its duration are important for preventing carbon build-up in iron and the intrusion of $CO_2$ into the hydrogen product. At a reduction temperature of 823K, oxide reduction by $H_2$ was considerably faster than reduction by CO. If the length of the reduction step exceeds optimal value, low levels of methane gas appeared in the off-gas. Furthermore, with longer durations of the reduction step and CO levels in the reducing gas greater than 10 vol.%, carbidization of the iron and/or carbon deposition in the bed exhibited the increasing pressure drop over the bed, eventually rendering the reactor inoperable. Reduction using a reducing gas containing 10 vol.% CO and a optimal reduction duration gave constant $H_2$ flow rates and off-gas composition over 10 redox reaction cycles.

• Journal of the Korean Society of Combustion
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• v.16 no.2
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• pp.1-8
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• 2011

As one of the main technologies for carbon capture and storage in power generation, oxy-coal combustion is being developed for field demonstration in Korea. This study presents the results of numerical simulation for combustion in a single-wall-fired 100 $MW_e$-scale boiler proposed for the initial design of the demonstration plant. Using a commercial CFD code, the detailed combustion, flow and heat transfer characteristics were assessed both for air-mode and oxy-mode combustion. The results show that stable combustion can be achieved in the dual mode operation with the current boiler configuration. However, the differences in the flow pattern and heat transfer between the two combustion modes need to be considered in the design and operation which is mainly due to the larger density and specific heat of $CO_2$ compared to $N_2$. Further development of the boiler design is required using improved numerical modeling for radiative heat transfer and combustion.

• Journal of the Korean Wood Science and Technology
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• v.52 no.2
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• pp.175-190
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• 2024

The increase in atmospheric carbon dioxide concentrations is known to be closely associated with climate change and global warming. In this sense, considering that facilities for appropriate education and experience on wood, which is a carbon pool, have been required, this study targets the Wood Cultural Experience Centers, which are in current operation, examines and evaluates their operation status and policy changes, and ultimately derives a successful positioning plan. To this end, it conducts a survey, and the results are as follows. First, as a result of the similarity analysis (KYST: Kruskal-Young-Shepard-Torgerson program) with facilities with leisure activities and educational functions, the Wood Cultural Experience Center have competition with natural recreation forests in terms of naturalness, and it has competition with the career experience center and youth training center in terms of experiential observation. Second, the result of positioning analysis of the attribute space map indicates that the Wood Cultural Experience Center is positively perceived in terms of such attributes as naturalness, experiential learning or recreation, and preservation of natural environment, but is negatively recognized in terms of accessibility, escape from daily life, and things to see.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.569-577
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• 2023

This study selected seven carbon-neutral villages, considering the characteristics of each region, including all five administrative districts of Changwon City, and proposed activation plans based on business evaluations through surveys of local residents and FGIs with leaders. The analysis showed that carbon-neutral education was the most important factor for activating carbon-neutral villages, with a response rate of 91.9% for 17 multiple-choice questions, followed by legal (ordinance) arrangements at 79.3% and village organization building at 74.1%. Based on this, the following activation plans through the participation of residents who are involved in the project of creating a carbon-neutral village in Changwon City were proposed. First, the characteristics of each carbon-neutral village model were classified into a resource circulation-based model, an environmental creation-based model, an environmental education and experience event-based model, and an energy efficiency-based model. Second, it is necessary to create and present carbon-neutral village growth stage guidelines for the growth of carbon-neutral villages. Third, manuals and teaching materials related to carbon neutrality, such as theories, issues, and practices, need to be produced and distributed for leaders and activists to easily apply and access for self-government operation of the village. Finally, if a carbon-neutral support center that is legally installable in Changwon City is established, it is expected that the lives of local residents will become more sustainable for carbon-neutral living in preparation for climate crises.

• Journal of environmental and Sanitary engineering
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• v.11 no.2
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• pp.1-7
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• 1996

The behavior of total organic carbon (TOC) and phosphate were observed for 15 days with immobilized activated sludge using polyacrylamide (PAA) by sequencing batch reactor (SBR). In the preparation of immobilized sludge by PAA, it was found that suitable acrylamide concentration for actual wastewater treatment was to be 15% through the batch test. When SBR system was operated in the repeated aerobic and anaerobic conditions, TOC removal efficiency was 92%. The uptake rate of phosphate was increased from 1.78 mg-P/g cell/hr on the 5th day of acclimation to 2.5 mg-P/g cell/hr on the 15th day of acclimation. And the total phosphorus content in PAA bead was increased from 40 mg-P/g cell on the 1st day of operation to 55 mg-P/g cell on the 15th day of operation. From this study, lowering the volume of aeration tank was possible when PAA bead was used in wastewater treatment and long operation was also possible without the settler.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.04a
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• pp.131-138
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• 2011

Currently, many forest residues have been generated by the National Forest Management Operation. Unfortunately, most of the forest residues are supposed to be used as raw materials for burning fuels like wood pellets. Even though the forest biomass must be effectively used for making high value-added products, they may be subject to disposable raw materials for wood pellets. Wood pellets are regarded as burning fuels with less contribution to the decrease in carbon gas emission, compared to raw materials for kraft pulps. In this study, we studied whether or not forest biomass mixed with various ages and, species could be used as raw materials for kraft pulps.

• The KSFM Journal of Fluid Machinery
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• v.12 no.4
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• pp.54-62
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• 2009

The feedwater heaters are Critical components in a nuclear power plant. As the operation years of heaters go by, the maintenance costs required for continuous operation increase. When the carbon steel components in nuclear make contact with running fluid, the wall thinning caused by FAC (flow accelerated corrosion) can be generated. Local wall thinning is inevitable at the area around wet steam entrance to be attacked due to the long term operation. Sometimes the shell with thinned wall is eventually ruptured. To identify the relationship between the local wall thinning and fluid behavior of the feedwater heater, the practical data of a plant, which were based on ultrasonic thickness measurement tests, were analyzed and CFD(Computed Fluid Dynamics) analyses were performed.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2765-2770
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• 2008

The purpose of tunnel ventilation system for long road tunnels is to keep certain levels of Visibility Index and the concentration of CO. Additional equipments such as jet fans are used in road tunnel to discharge pollutants in the road tunnel. The control algorism of tunnel ventilation system takes the value of sensors as input, and then gives the operation method of jet fans in tunnel as output. Information on the variation of CO concentration in tunnel when jet fans are running is needed to minimize their operation time. Numerical analysis is used in this paper because of the difficulty of conducting experiments under standard condition for ventilation of road tunnel. The concentration of CO has been calculated by using 3-dimensional CFD under transient condition with speed of cars, quantity of air ventilation, and the results for various operation position of jet fans are compared.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.2
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• pp.159-167
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• 2002

The operation results of the 2kW class plate type reformer, which has several advantages compared with the tubular burner type reformer, are analyzed. This plate type reformer is composed of six combustion chambers and five reforming chambers by turns. The methane conversion rate at 1.6 absolute pressure is about 84%, which is reasonably similar to theoretical value, 85.3%. Though the abrupt interruption was made just by the carbon deposition during heating the fuel line to combustion chambers around 200 hours operation, the overall steady state operation is more than 450 hours. These operation results show the verification of long run performance and the possibility of direct connection between plate reformer and fuel cell stack.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3878-3887
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• 2022

For the future energy-mix policy for carbon neutrality, demand for the capability of load-follow operation has emerged in nuclear power plants in order to accommodate the intermittency of renewable energy. The short-term decay heat analysis is also required to evaluate the decay heat level varied by the power level change during the load-follow operation, which is a very important parameter in terms of short-term decay heat removal during a grace time. In this study, the short-term decay heat level for 10 days after the shutdown was evaluated for both seasonal and daily load-follow cases. Additionally, the nuclide-wise contribution to the accumulated decay heat for 10 days was analyzed for further understanding of the short-term decay heat behavior. The result showed that in the seasonal case, the decay heat level was mainly determined by the power level right before the shutdown and the amount of each nuclide was varied with the power variation due to the long variation interval of 90 days. Whereas, in the daily case, the decay heat level was strongly impacted by the average power level during operation and meaningful mass variations for those nuclides were not observed due to the short variation interval of 0.5 days.