• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.234-240
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• 2016

Energetically-modified material using reject fly ash (RFA), generated from thermal power plants, was manufactured to investigate the effect of the material on the physical and chemical characteristics of cement mortar. In order to modify reject fly ash, a vibration mill was used. Particle size, grain shape, and crystal structure of the ash were analyzed. Then, the compressive strength of the mortar using energetically-modified reject fly ash (ERFA) was measured. Microstructure and X-ray diffraction (XRD) patterns were also used in the analysis. As the replacement rate of ERFA increased, the value of the compressive strength tended to decrease. However, it was found that the compressive strength values of 7 and 28 days-cured specimens were higher than those of conventional ordinary Portland cement (OPC) mortar with 10 % replacement rate condition.

• Journal of the Ergonomics Society of Korea
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• v.32 no.1
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• pp.47-58
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• 2013

Objective: The aim of this study is to review the job stress measurement for applying in nuclear power plants(NPPs). Background: The standard and guideline to evaluate and manage the job stress is insufficient in NPPs. Although job stress might have a negative effect on task performance particularly it can be related with human error in NPPs. Method/Results: This paper considered the objective and subjective stress measurements. One of the questionnaire(Korean Occupational Stress Scale) and the experiment method was investigated to apply in NPPs. KOSS was analyzed about the inter item consistency and correlation with the workload, and relative importance. In the objective evaluation considered the experiment method for the physical and mental job stress and analyzed from the phased point of view. Conclusion/Application: The measurement and criteria to evaluate job stress for operators must be complemented on the job characters and environments in NPPs. This study may support to confirm and manage the job stress in NPPs. The study of more specific methodology on job stress in NPPs is required on the basis of this paper.

• Nuclear Engineering and Technology
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• v.50 no.4
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• pp.606-612
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• 2018

Many nuclear power plants in Japan are approaching the end of their planned operational life spans. They must be decommissioned safely in the near future. Using augmented reality (AR), workers can intuitively understand information related to decommissioning work. Three-dimensional (work-site) reconstruction models of dismantling fields are useful for workers to observe the conditions of dismantling field situations without visiting the actual fields. This study, based on AR and work-site reconstruction models, developed and evaluated an information reference system. The evaluation consists of questionnaires and interview surveys administered to six nuclear power plant workers who used this system, along with a scenario. Results highlight the possibility of reducing time and mitigating mistakes in dismantling fields. Results also show the ease of referring to information in dismantling fields. Nevertheless, it is apparently difficult for workers to build reconstruction models of dismantling fields independently.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.93-100
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• 2003

An estimation methodology of the mass and energy (M/E) release due to the main steam line break (MSLB) has been developed with the RETRAN-3D code. In the case of equipment qualification (EQ), the over-estimated temperature would exceed the design limits of some cables or valves. In order to have a more flexible EQ profiles from the MSLB M/E release, the methodology with the best-estimated code was used. The major conditions affecting the MSLB M/E were found to be the initial SG level, heat transfer between primary and secondary sides, power level, operable protection system, main or auxiliary feedwater availability, and break conditions. The RETRAN-3D models were developed for the Kori unit 1 (KRN-1) which is typical two loop Westinghouse (WH) designed plant. Particularly, a detailed model of the steam generators was developed to estimate a more realistic two-phase heat transfer effect of the steam flow. After the modeling, the methodology has been developed through the sensitivity analyses. The M/E release data generated from the analyses have been used as the input to the inside containment pressure and temperature (P/T) analysis. According to the results at the point of view containment P/T, the Kori unit 1 can have more margin of 5∼15 ㎪ in pressure and 8∼15$^{\circ}C$ in temperature.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.10
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• pp.1062-1067
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• 2015

Floating architecture is a type of building that is geographically located on a sea or a river. It floats under the influence of buoyancy, and does not have an engine for moving it. Korea is a peninsula surrounded by sea except on the north side, so floating architectures have been mainly focused on two points: solving the issue of small territory and providing various leisure & cultural spaces. Floating architectures are expected to save energy effectively, if they use sea water heat, which is known to be clean energy with infinite reserves. To use sea water heat as the heat source and/or heat sink, this study proposes a model in which a sea water heat exchanger is embedded in the concrete structure in the lower part of the floating architecture that is submerged under the sea. Based on the results of performance evaluations of the sea water heat exchanger using CFD (computational fluid dynamics) analysis and mock-up experiments under various conditions, it is found out that the temperature difference between the inlet and outlet of the heat exchanger is in the range of $3.06{\sim}9.57^{\circ}C$, and that the quantity of heat transfer measured is in the range of 3,812~7,180 W. The CFD evaluation results shows a difference of 5% with respect to the results of mock-up experiment.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.202-204
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• 2009

Erosion is a common failure mode of materials frequently encountered in plant and power industry. Although the erosion resistance of Fe-base alloy has been inferior to the other expensive materials, it is expected that the strain-induced martensitic transformation can impart high erosion resistance to Fe-base alloy. The key technology to develop Fe-base metal cored welding wire for erosion resistant overlay welding may include the strain-induced metallurgy for hardening rate control and the welding flux metallurgy for dilution control. Sophisticated studies showed that the strain-induced martensitic transformation behavior was related to the critical strain energy which was dependent on the alloy composition. Dilution and bead shape of overlay weld were proved to be affected by metal transfer mode during gas tungsten arc welding and elements in welding fluxes. It was considered that the highly erosion resistant Fe-base overlay weld could be achieved by precise control of alloy composition to have proper level of critical strain energy for energy absorption and welding flux formulation to have small amount of deoxidizing metallic elements for dilution.

• New & Renewable Energy
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• v.6 no.4
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• pp.15-29
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• 2010

In order to make the best choice for $CO_2$ abatement using renewable energy technologies, it is important to be able to adapt these technologies on the basis of their sustainability, which may include a variety of environmental indicators. This study examined the comparative sustainability of renewable technologies in terms of their life cycle $CO_2$ emissions and embodied energy, using life cycle analysis. The models developed were based on case studies of bioenergy pilot plant in P city of Kyungki province. Final results were total emission of $CO_2$ in Pocheonsi is 670,041 $tCO_2$, around 500,877 $tCO_2$ for electricity and for heat generation, and 169,164 $tCO_2$ for transportation. When used $1,984\;m^3$/day of waste (pig manure etc.) and operated CHP with wood chips of 144,664 ton/year, the $CO_2$ emission in P city was left as is an emission of 449,274 $tCO_2$ and an abatement of $CO_2$ in this region was increased by 32.9%.

• The KSFM Journal of Fluid Machinery
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• v.18 no.3
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• pp.60-65
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• 2015

This paper deals with performance characteristics and efficiencies of Pelton turbine can be applied as one of ERDs (Energy Recovery Devices) of PRO (Pressure Retarded Osmosis) system for desalination. The objective of this study is experimentally estimating the performance of micro-scale Pelton turbine for PRO pilot plant. Especially the performance characteristics with variations of jet nozzle diameter of Pelton turbine are discussed in detail. In order to do this, lab scale test rig of Pelton turbine was made for performance test, which includes water tank, Pelton wheel with buckets, jet nozzle and torque brake and so on. The parameter effects related on Pelton turbine's efficiency were investigated and discussed on the influence of the variations of load and speed ratio.

• Nuclear Engineering and Technology
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• v.29 no.3
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• pp.229-239
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• 1997

To investigate the realistic behavior of mass and energy release and resultant containment response during large break Loss of Coolant accident (LOCA), analyses are performed for Yonggwang (YGN) 3&4 nuclear power plants by using a merged version of RELAP5/CONTEMPT4 computer code. Comparative analyses by using conservative design computer codes are also peformed. The break types analyzed are the double-ended guillotine breaks at the cold leg and hot leg. The design analysis resulted in containment peak pressure during post-blowdown phase for the cold leg break. However, the RELAP5/CONTEMPT4 analyses show that the containment pressure has a peak during blowdown phase, thereafter it decreases monotonously without the second port-blowdown peak. For the hot leg break, revised design analysis shows much lower pressure than that reported in YGN 3&4 final safety analysis report. The RELAP5/CONTEMPT4 analysis shoos similar trend and confirmed that the bypass flow through the broken loop steam generator during post-blowdown is negligibly small compared to that of cold leg break. The low pressure and temperature predicted tv realistic analysis presented in this paper suggest that the design analysis methodology contains substantial margin and it can be improved to provide benefit in investment protection, such as, relaxing plant technical specifications and reducing containment design pressure.

• Journal of the Korean Solar Energy Society
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• v.33 no.2
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• pp.50-55
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• 2013

On a plan for the Winter Olympics 2018, Korean government is in the process of the world's first use of ocean energy for the Olympic ice-rink. This technology will be applied to a seaside town and have possibility of an export industry. In this study, we researched facilities and system for P ice-rink that acts as a cultural center as well as a physical plant in Busan and provided the way that apply by seawater heat source. Also, existing system and seawater heat source system of P ice-rink was analyzed by the most commonly used life cycle cost analysis among economics methods. Such economics data for ice-rink using seawater will be utilized by a basic information.