• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.20 no.1
• /
• pp.99-110
• /
• 2022

In decommissioning a nuclear power plant, numerous concrete structures need to be demolished and decontaminated. Although concrete decontamination technologies have been developed globally, concrete cutting remains problematic due to the secondary waste production and dispersion risk from concrete scabbling. To minimize workers' radiation exposure and secondary waste in dismantling and decontaminating concrete structures, the following conceptual designs were developed. A micro-blast type scabbling technology using explosive materials and a multi-dimensional contamination measurement and artificial intelligence (AI) mapping technology capable of identifying the contamination status of concrete surfaces. Trials revealed that this technology has several merits, including nuclide identification of more than 5 nuclides, radioactivity measurement capability of 0.1-10⁷ Bq·g^-1, 1.5 kg robot weight for easy handling, 10 cm robot self-running capability, 100% detonator performance, decontamination factor (DF) of 100 and 8,000 cm²·hr^-1 decontamination speed, better than that of TWI (7,500 cm²·hr^-1). Hence, the micro-blast type scabbling technology is a suitable method for concrete decontamination. As the Korean explosives industry is well developed and robot and mapping systems are supported by government research and development, this scabbling technology can efficiently aid the Korean decommissioning industry.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.337-340
• /
• 2003

Currently the number of project ordered as Construction Management is increasing. In advanced country, critical success factor of construction industry and case study is used for increasing productivity of construction project. This study presents the check list of critical success factor and analyzescase study of Construction management project in order to apply Construction Management Project in domestic industry.

• Journal of Ecology and Environment
• /
• v.40 no.2
• /
• pp.125-135
• /
• 2016

Background: The objectives of this study were to establish a swimming capability model for largemouth bass using the FishXing (version 3) program, and to determine the swimming speed and feasibility of fish passage through a waterway tunnel. This modeling aimed to replicate the waterway tunnel connecting the Andong and Imha Reservoirs in South Korea, where there is a concern that largemouth bass may be able to pass through this structure. As largemouth bass are considered an invasive species, this spread could have repercussions for the local environment. Results: Flow regime of water through the waterway tunnel was calculated via the simulation of waterway tunnel operation, and the capability of largemouth bass to pass through the waterway tunnel was then estimated. The swimming speed and distance of the largemouth bass had a positive linear function with total length and negative linear function with the flow rate of the waterway tunnel. The passing rate of small-size largemouth bass (10-30 cm) was 0%at a flow of $10m^3/s$ due to rapid exhaustion from prolonged upstream swimming through the long (1.952 km) waterway tunnel. Conclusions: The results of FishXing showed that the potential passing rate of large size largemouth bass (>40 cm) through the waterway tunnel was greater than 10%; however, the passage of largemouth bass was not possible because of the mesh size ($3.4{\times}6.0cm$) of the pre-screening structures at the entrance of the waterway tunnel. Overall, this study suggests that the spread of largemouth bass population in the Imha Reservoir through the waterway tunnel is most likely impossible.

• Fire Science and Engineering
• /
• v.27 no.5
• /
• pp.38-43
• /
• 2013

An automatic spreading fire extinguisher usually installed in a closed area like a boiler room, a laundry store or a restaurant's kitchen room is one of the fire protection equipments. This extinguisher automatically discharges dry powder, extinguishing fire. As this extinguisher has the extinguishing capability applicable to the nominal protection area, objects outside the area cannot be properly extinguished. However only its number is being requested according to the floor area in the related laws, and the extinguishing capability depends on the distance from a fire source. In this study we tried to investigate the extinguishing capability of the automatic spreading fire extinguisher in accordance with horizontal separation distance from a fire source. It appeared that the maximum horizontal separation distance was about 30 cm for both class A and B fire to be certainly extinguished.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.8
• /
• pp.994-1000
• /
• 2011

In this study, the piezoelectric fan cooling system is investigated. In order to find the proper geometry and configuration, the numerical model for the flow field and heat transfer investigation is used. A simplified nonlinear deformation model is employed for transient solutions of a piezoelectric fan with the dynamic mesh and user defined function capability. The results show that the cooling is most effective when the length of a piezoelectric fan is 5 cm and the cooling plate is 3 cm. The results can be used to develop a new design method of heat sink for piezoelectric fans.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2005.05a
• /
• pp.133-136
• /
• 2005

This study provides the method how to improve the productivity of a project using CM's constitutive methods. Construction industry in Korea was protected by the government and they have been grown with only their construction technology until today. It results Korean Construction is behind the advanced countries in terms of Engineering fields and construction management skills. This study compares the difference between the construction system of Korea and Europe and Asia. And then, it proposes the method how to compete with the other countries. which introduce the CM technique into the construction project in the beginning stage. Hopefully, this study is recognised as the basic strategy to improve the capability of Korean construction management.

• Journal of the Korean Wood Science and Technology
• /
• v.50 no.2
• /
• pp.126-133
• /
• 2022

In this study, I used wood pellets as an eco-friendly sound-absorbing material. The aim of the research was to analyze the effect of the filling height of wood pellets on sound absorption. This was done using two types of wood pellets of different lengths (A group: 1.5-3 cm, B group: less than 1.5 cm). With increasing filling height of the wood pellets, the optimum sound absorption shifted towards a lower frequency. The group B wood pellets had better sound absorption capacity than the group A ones. The optimum sound absorption coefficient of group A filled to a height of 7 cm was 0.722 at 864 Hz. On the other hand, that of group B filled to a height of 7 cm was 0.764 at 862 Hz, 5.82% higher than that of group A. While wood pellets are used as an eco-friendly fuel, the results of this study suggest the possibility of using wood pellets as an eco-friendly sound-absorbing material.

• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.388-393
• /
• 2003

Since the Construction Management(CM) was introduced into the Korea construction industry, the efforts for acceleration of CM adaption have been continued. The fact that an owner organization has the essential key to successful application of CM delivery method is true, but there has been no study on owner's organization. An owner should decide their organization type and measure their current needs of each CM business functions for successful application of CM. After the needs of CM business functions are measured, the owner should reinforce their required business functions through strengthening their in-house capability or outsourcing. Thus, this paper defines four kinds of owner organization type and suggest the form for evaluation of owner's CM ability and analyze about needs of each type's CM ability through making up question.

• Journal of Electrochemical Science and Technology
• /
• v.8 no.4
• /
• pp.338-343
• /
• 2017

Activated carbon has lower electrical conductivity and reliability than other carbonaceous materials because of the oxygen functional groups that form during the activation process. This problem can be overcome by doping the material with heteroatoms to reduce the number of oxygen functional groups. In the present study, N, F co-doped activated carbon (AC-NF) was successfully prepared by a microwave-assisted hydrothermal method, utilizing commercial activated carbon (AC-R) as the precursor and ammonium tetrafluoroborate as the single source for the co-doping of N and F. AC-NF showed improved electrical conductivity ($3.8\;S\;cm^{-1}$) with N and F contents of 0.6 and 0.1 at%, respectively. The introduction of N and F improved the performance of the pertinent supercapacitor: AC-NF exhibited an improved rate capability at current densities of $0.5-50mA\;cm^{-2}$. The rate capability was higher compared to that of raw activated carbon because N and F codoping increased the electrical conductivity of AC-NF. The developed method for the co-doping of N and F using a single source is cost-effective and yields AC-NF with excellent electrochemical properties; thus, it has promising applications in the commercialization of energy storage devices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.9
• /
• pp.833-839
• /
• 2005

This work describes the effect of the number of roll pressing and the composition of carbon black on the electric and mechanical properties of carbon-PTFE electrode, in which composition is MSP20 : carbon black : $PTFE\;=\;95-X\;:\;X\;:\;5wt.\%$. It was found that the best electric and mechanical properties were obtained for sheet electrode roll pressed about 15 times and for sheet electrode, in which composition is MSP20 : carton black $PTFE\;=\;80\;:\;15\;:\;5wt.\%$. These behaviors could be explained by the network structure of PTFE fibrils and conducting Paths linked with carbon blacks, respectively. On the other hand, cell capacitor using the sheet electrode with $15wt.\%$ of carbon black attached on aluminum current collector with the electric conductive adhesive, in composition is carbon black $CMC\;=\;70\;:\;30wt.\%$, has exhibited the best rate capability between $0.5\;mA/cm^2\~100\;mA/cm^2$ current density and the lowest ESR.