• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2A
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• pp.123-130
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• 2012

A cooling system is indispensable for the fossil and nuclear power plants which produce electricity by rotating the turbines with hot steam. A cycle of the typical cooling system includes pumping of seawater at the intake pump house, exchange of heat at the condenser, and discharge of hot water to the sea. The cooling type of the nuclear power plants in Korea recently evolves from the conventional surface intake/discharge systems to the submerged intake/discharge systems that minimize effectively an intake temperature rise of the existing plants and that are beneficial to the marine environment by reducing the high temperature region with an intensive dilution due to a high velocity jet and density differential at the mixing zone. It is highly anticipated that the future nuclear power plants in Korea will accommodate the submerged cooling system in credit of supplying the lower temperature water in the summer season. This study investigates the approach flow patterns at the velocity caps and discharge flow patterns from diffusers using the 3-D computational fluid dynamics code of $FLOW-3D^{(R)}$. The approach flow test has been conducted at the velocity caps with and without a cap. The discharge flow from the diffuser was simulated for the single-port diffuser and multi-ports diffuser. The flow characteristics to the velocity cap with a cap demonstrate that fish entrainment can significantly be minimized on account of the low vertical flow component around the cap. The flow pattern around the diffuser is well agreed with the schematic diagram by Jirka and Harleman.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.578-584
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• 2021

This study comparatively analyzed the properties of hydration reaction and strength development of four types of pond ash(PA) and fly ash(FA), aiming for the effective use of PA. The PA whose chlorine content was highest due to the seawater movement method had a faster setting time, higher cumulative heat, and greater initial strength development than those of FA due to the acceleration of the cement hydration reaction. However, the activity factor increase rate decreased after seven days of curing due to the rapid generation of early hydrates. The PA that contained impurities, such as a large amount of unburned carbon, had a delayed setting time due to the lower hydration reaction. Moreover, the strength was degraded in all curing ages. The PA whose chlorine content was lower due to the freshwater movement method and the amorphous content exhibited similar hydration reactivity and strength development characteristics compared to that of FA. The thermogravimetric analysis results verified that it had a similar level of Ca(OH)₂ consumption and pozzolanic reactivity with that of FA. Conclusively, it is necessary to expand the application of the freshwater movement method and manage the ignition loss to raise PA's usability.

• Journal of the Korean Geographical Society
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• v.29 no.1
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• pp.46-64
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• 1994

Among every civilized people salt has been recognized as an essential foodstuff to the human society without which even man's survivor is unthinkable. The cultural-anthropological meaning of salt is estimated highly as well, and in geographical perspective salt itself symbolize regional interrelationship. Playing a decisive role in freeing innermost settlement from isolation, salt aiso made a contribution to expanding human habitats. This study tries to reconstruct historica geography of 18th and 19th century surrounding traditional salt-roasting (chayeom). The Joolpo Inlet area which is located on the mid-western coast in Honem Region is selected for study area. Established on the basis of optimum physical geographical conditions such as topography, climate and vegetation, salt-making of Joolpo Inlet area was run dynamically with the sudden turn of events in the 18-19th century which was chacterized as an age of transition from medieval society to modern one. In this paper the writer attempts to clarify mainly following three points: physical conditions and socio-economic background leading to the initiation and later development of roasting of salt in Joolpo Bay; distribution of saltworks; methods of saltmaking. Main points drawn from these analyses can be summarized as follows: of iron pan and cow-drawn tools rendered labour-saving and output growth. 1, Saltworks of Joolpo Inlet area in the 18-19th century were distributed evenly over Kobu, Puan, Mujang and Heungduck counties among which Kobu's was located in Puanmyon - a sort of exclave. All saltworks belonging to above four counties were clasified as most lucrative ones in Honam Region on government archives. In particular, Gumdang saltwork which belongs to Mujang county is noteworthy in that it was first introduced by one Paekje priest in 6th century and therefore it provides a clue to examine the history of salt-roasting of Joolpo Inlet area. In light of the fact that temple or monastery economy, regardless of East and West, has been closely connected with traditional industry, the case of Gumdang is not unusual. 2. The process of saltmaking follows this order: harrowing of salt field exposed to solar heat; construction of saltern mound with saline earth; acquiring of brine by leaching saline earth; roasting of salt. Salterns (saltworks) are consisted with various salt making facilities such as roasting shed, saltern mound, salt field, salt well) salt pit or brine pit) and seawater reservoir. Among them roasting shed which is constructed chiefly with hundreds of pieces of pine tree as a frame and with straw as roof and wall is customarily considered as an unit of saltwork. And inside it is saltpan made of two kinds of materials, that is iron pan or plaster pan. The area attached to one unit of roasting shed is approximately 1 ha, and that of saltern mound is a tenth of it.

• Economic and Environmental Geology
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• v.56 no.2
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• pp.125-138
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• 2023

Most of previous cesium (Cs) sorbents have limitations on the treatment in the large-scale water system having low Cs concentration and high ion strength. In this study, the new Cs sorbent that is eco-friendly and has a high Cs removal efficiency was developed by improving the coal mine drainage treated sludge (hereafter 'CMDS') with the addition of Na and S. The sludge produced through the treatment process for the mine drainage originating from the abandoned coal mine was used as the primary material for developing the new Cs sorbent because of its high Ca and Fe contents. The CMDS was improved by adding Na and S during the heat treatment process (hereafter 'Na-S-CMDS' for the developed sorbent in this study). Laboratory experiments and the sorption model studies were performed to evaluate the Cs sorption capacity and to understand the Cs sorption mechanisms of the Na-S-CMDS. The physicochemical and mineralogical properties of the Na-S-CMDS were also investigated through various analyses, such as XRF, XRD, SEM/EDS, XPS, etc. From results of batch sorption experiments, the Na-S-CMDS showed the fast sorption rate (in equilibrium within few hours) and the very high Cs removal efficiency (> 90.0%) even at the low Cs concentration in solution (< 0.5 mg/L). The experimental results were well fitted to the Langmuir isotherm model, suggesting the mostly monolayer coverage sorption of the Cs on the Na-S-CMDS. The Cs sorption kinetic model studies supported that the Cs sorption tendency of the Na-S-CMDS was similar to the pseudo-second-order model curve and more complicated chemical sorption process could occur rather than the simple physical adsorption. Results of XRF and XRD analyses for the Na-S-CMDS after the Cs sorption showed that the Na content clearly decreased in the Na-S-CMDS and the erdite (NaFeS₂·2(H₂O)) was disappeared, suggesting that the active ion exchange between Na⁺ and Cs⁺ occurred on the Na-S-CMDS during the Cs sorption process. From results of the XPS analysis, the strong interaction between Cs and S in Na-S-CMDS was investigated and the high Cs sorption capacity was resulted from the binding between Cs and S (or S-complex). Results from this study supported that the Na-S-CMDS has an outstanding potential to remove the Cs from radioactive contaminated water systems such as seawater and groundwater, which have high ion strength but low Cs concentration.