• Journal of the Korea Institute of Building Construction
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• v.8 no.4
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• pp.115-121
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• 2008

The present study performed low-pressure steam curing with mortar specimens in order to examine the temperature profile and strength development of steam curing in high-strength specimens of 100MPa. In addition, as a basic research to utilize PC products, we examined the effects of curing temperature and time in steam curing cycle on strength development resulting from the hydration of cement within the range of high strength by changing four factors affecting the quality of PC displacement time, peak curing temperature, peak temperature duration, and ascending and descending gradient of temperature - in various patterns, and analyzed the optimal strength development characteristic based on the relation between temperature profile and strength development. With regard to the high-temperature curing characteristic of PC, we performed an experiment on the strength characteristic according to the temperature profile of high-strength mortar, and from the results of the experiment according to curing characteristic, displacement time, peak curing temperature, peak temperature duration, and ascending and descending gradient of temperature, we drew conclusions as follows.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1603-1604
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• 2007

The load of power plants changes every from time to time according to which steam flow of boiler changes. the feed water control is very important for the power plant to be operated in its stability conditions. In case of circulation type boiler, the instability of feed water control leads to instability of drum level control. The higher level of drum water can induce bad quality steam to go into turbine which means the possibility of damage. The lower level of drum water can induce the tubes of boiler water wall to be overheated. In case of once through type boiler, the instability of feed water control leads to bad cooling of superheaters. The less the feed water flow is, the more heated the superheater is. It is necessary for the turbine driving feed water pump to be controlled for the optimal feed water flow in the large capacity power plant. The speed of turbine is controled for the feed water flow. By the way, the optimal control of steam valve is necessary for the speed control of turbine. Therefore, the various kinds of the steam valve structures are introduced in this paper

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1338-1348
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• 2016

A novel fully passive small modular superheated water reactor (SWR) for underwater deployment is designed to produce 160 MWe with steam at $500^{\circ}C$ to increase the thermodynamic efficiency compared with standard light water reactors. The SWR design is based on a conceptual 400-MWe integral SWR using the internally and externally cooled annular fuel (IXAF). The coolant boils in the external channels throughout the core to approximately the same quality as a conventional boiling water reactor and then the steam, instead of exiting the reactor pressure vessel, turns around and flows downward in the central channel of some IXAF fuel rods within each assembly and then flows upward through the rest of the IXAF pins in the assembly and exits the reactor pressure vessel as superheated steam. In this study, new cladding material to withstand high temperature steam in addition to the fuel mechanical and safety behavior is investigated. The steam temperature was found to depend on the thermal and mechanical characteristics of the fuel. The SWR showed a very different transient behavior compared with a boiling water reactor. The inter-play between the inner and outer channels of the IXAF was mainly beneficial except in the case of sudden reactivity insertion transients where additional control consideration is required.

• Food Engineering Progress
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• v.22 no.4
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• pp.328-336
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• 2018

The aim of this study was to investigate the effect of pretreatments on quality of frozen peach. Pretreatments including steam blanching, water blanching, high pressure, and osmotic dehydration were applied to two varieties (Daeokgye and Hwangdo). Pretreated peaches were frozen and thawed at $-20^{\circ}C$ and $5^{\circ}C$, respectively. Steam blanching and osmotic dehydration with ascorbic acid reduced ${\Delta}E$ values without change of pH and acidity. Osmotic dehydration with sucrose decreased drip loss and increased brix. Freezing/thawing resulted in an increase of maximum force, while maximum force decreased with increasing time of steam and water blanching. Furthermore, osmotic dehydration with calcium chloride increased maximum force. High pressure decreased maximum force of Daeokgye and increased that of Hwangdo compared with non-treatment. Total polyphenol content, DPPH radical scavenging activity, and ABTS radical scavenging activity were improved by pretreatment including steam blanching, blanching, and osmotic dehydration with ascorbic acid.

• Food Science and Preservation
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• v.14 no.2
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• pp.201-206
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• 2007

This study was designed to investigate quality characteristics of alcohol fermentation from 5 barldy cultivars teated with non-steam and steam. In alcohol fermentation treated with non-steam, alcohol concentration reached to 1.7% for naked berley, 2.9% for naked waxy barley and 4.3% for Hinchalssalbori. However, no fermentation was occurred with baney and waxy barley. When the barley cultivars were steamed, alcohol concentrations showed to be higher than those not steamed. In sugar concentration from non-steam, both barley and waxy barley showed to have approximately $9.0\;^{\circ}Brix$ and naked barley, naked waxy barley and Hinchalssalbori showed to have approximately $5.0\;^{\circ}Brix$. When the burley cultivars were steamed, sugar concentration was decreased as alcohol concentration was increased Interestingly, sugar concentrations in barley cultivars were fast dropped more than 50% following alcohol fermentation except naked barley k alcohol fermentation treated with non-steam, total acidity of Hinchalssalbori was 0.51%, but the others showed more than 0.80%. So except for Hinchalssalbori, it was possible that acidification occurred during the fermentation. In total acidity from steam, all samples showed less than 0.3%. In flee sugar from non-steam, total free sugar contents of barley and waxy barley were approximately 4,000.0mg% and contents of naked barley naked waxy barley and Hinchalssalbori were each approximately 300.0 mg%. Free sugar from steam was increased as sugar concentration increased. In conclusion, barley cultivars were evaluated to be not suitable at alcohol fermentation treated with non-steam.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.101-108
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• 2003

The purpose of this study is to develop an entrainment model of the Pressurized Water Reactor (PWR) U-tube Steam Generator (SG) for Main Steam Line Break (MSLB) analyses. Generally, the temperature of the inside containment vessel at MSLB is decreased by introducing the liquid entrainment effect. This effect makes a profit on the aspect of integrity evaluation for Equipment Environmental Qualification (EEQ) in the containment. However, the target plant, Kori unit 1 does not have the entrainment data. Therefore, this study has been performed. RETRAN-3D and LOFTRAN computer programs are used for the model development. There are several parameters that are used for the initial benchmark, such as Combustion Engineerings (CE) experimental data and the RETRAN-3D model which describes the test leg. A sensitivity study is then performed with this model in which the model parameters are varied until the calculated results provide reasonable agreement with the measured results for the entire test set. Finally, a multiplication factor has been obtained from the 95/95 values of the calculated (best-estimate) quality data relative to the measured quality data. With this new methodology, an additional temperature margin of about 40$^{\circ}C$ can be obtained. So, the new methodology is found to have an explicit advantage to EQ analyses.

• Special Issue of the Society of Naval Architects of Korea
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• 2006.09a
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• pp.46-52
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• 2006

For ships, heat resistant coating is applied on the aluminized steel pipe systems dealing with high temperature steam over $200^{\circ}C$. The coatings on these steam pipes should retain both heat resistance and anti-corrosion properties to provide long-term resistance against coating defects (rust, delamination and crack) under the harsh outdoor environment including repeated seawater wetting and condensation. Thus, it is important to improve the coating qualities and to reduce maintenance works for these steam pipe systems. In this study, five different commercial heat resistant coatings (A, B, C, D, E) were selected for evaluation. Various physical properties of these coatings were evaluated on the coatings applied on the aluminized steam pipes. FT-IR analysis was also employed to identify the factors contributing the degree of heat resistance and durability of each coating material. The results indicated that the heat resistance capacity of coatings increased with the increase of silicon content as well as the decrease of substituent content. Both products C and D showed the best coating qualifies, which can be standard coating systems for future steam pipe areas.

• Journal of Korean Society for Quality Management
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• v.47 no.3
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• pp.425-435
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• 2019

Purpose: The purpose of this study was to resolve the Naval ship's Local Operation Panel(LOP) malfunction problems which caused by overheating in summer season and dispatching to equatorial regions. Methods: Instead of using dual type heat insulation materials(consist with ceramic wool and glass wool), aerogel heat insulation materials were used for decreasing heat emissions from gas-turbine heat waste steam pipes passing water-jet- room. Experiment and Computational analysis of heat flow were conducted to analyze the internal room temperature changes. Results: The results of this study are as follows; The aerogel heat insulation materials suppress heat emission more efficiently than dual type insulation materials. The cold surface temperature of insulation was far more decreased and internal room, LOP surface temperature also showed significant results too. Conclusion: The substituted heat insulation materials appeared remarkable performance in decreasing room temperature that it could be used for suppressing the LOP overheatings and malfunctions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.886-893
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• 2000

The Characteristics of dividing the dispersed bubble, plug, and slug steam-water flow in the horizontal junctions with horizontal branches have been experimentally investigated. The experimental investigation of the separation phenomena in a $45^{\circ}$ horizontal wye with equal pipe inner diameter of 25 mm is presented to provide a data base for the development and verification of the analytical models. The phase separation and pressure distribution in the three legs of each test section are obtained through the set of measurements made in the present work. And the dependence of phase separation on different parameters, such as inlet quality and mass flux, is discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.333-337
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• 2004

Steam Generator is one of the most important structural part of nuclear power plant. It is manufactured by various steel forgings such as shell, head, torus and tubesheet. These steel forgings have been made by open die forging process. After steel melting and ingot making, open die forging has been carried out to get a good quality which means high soundness and homogeniety of the steel forgings by using high capacity hydraulic press. This paper introduced the open die forging process and manufacturing experience of large tubesheet forgings which will be used for the steam generator of 1,400MW nuclear power plant.