• 한국건축시공학회지
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• 제8권4호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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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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• 제48권6호
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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.

• 산업식품공학
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• 제22권4호
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• pp.328-336
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• 2018

본 연구에서는 품종 및 전처리방법에 따른 복숭아의 냉해동 특성을 비교하였다. 전처리 없이 냉해동한 대옥계와 황도는 변색과 maximum force 증가, 드립로스 발생 현상을 보였는데, 이러한 문제점들은 전처리 방법에 의해 개선할 수 있었다. 전처리 직후 냉동 전에 전처리 별로 수분함량을 비교했을 때 sucrose를 포함한 삼투건조 시 수분이 감소하였으며 이는 해동 후 drip loss 감소에 영향을 주었다. 변색과 성분 및 항산화능력의 감소는 SB 3분 이상, ascorbic acid를 포함한 삼투건조 시 크게 개선되었다. Maximum force는 steam blanching, water blanching 시간이 증가할수록 감소하였으며, ACS의 경우 다른 삼투건조 처리구에 비해 높은 값을 보였다. 두 품종 모두 sucrose를 포함한 삼투건조 시 Brix가 크게 증가하였으며 pH와 산도는 품종 별로 차이는 있었으나 전처리 방법에 따라서는 큰 차이가 없었다. 물성 및 색도, 드립로스 등으로 판단하였을 때 steam blanching 3분 처리구가 전처리 조건 중 가장 적절한 방법으로 생각된다.

• 한국식품저장유통학회지
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• 제14권2호
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• pp.201-206
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• 2007

본 연구에서는 비열 및 열처리에 따른 5종류의 보리 품종별 알코올발효 특성을 조사하였다. 비열처리구에서 알코올 함량은 쌀보리, 찰쌀보리 및 흰찰쌀보리가 각각 1.7, 2.9 및 4.3%로 나타났으며 보리와 찰보리는 발효가 되지 않았다. 열처리구에서 비열처리구에 비해 전반적으로 골은 알코올생성능을 보였다. 당도는 비열처리구의 보리 및 찰보리가 $9.0\;^{\circ}Brix$ 전후의 높은 당도를 나타내었고 쌀보리, 찰쌀보리, 흰찰쌀보리가 $5.0\;^{\circ}Brix$ 전후의 당도로 나타났다. 열처리구의 당도는 알코올생성능과 반비례 경향이었으며 알코올발효 종료 후 쌀보리를 제외하고는 당함량이 50%이상 감소되었다. 비열처리구에서 산도는 흰찰쌀보리가 0.51%로 나타났으며 나머지 시료들은0.80%이상의 수치를 보여 산패의 가능성을 보였고, 열처리구에서는 모든 시료들이 0.3%이하의 수치로 나타났다. 유리당은 비열처리구의 보리와 찰보리가 알코올을 생성하지 않았으므로 유리당 총함량은 4,000.0 mg%전후로 높게 나타났고 쌀보리, 찰쌀보리 및 흰찰쌀보리는 300.0mg%전후의 함량으로 나타났다. 열처리구에서는 당도가 높을수록 유리당 총 함량이 높게 나타났으며 이상의 결과 보리는 열처리에 비해 비열처리 알코올 발효에는 적합하지 않았다.

• 에너지공학
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• 제12권2호
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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.

• 대한조선학회 특별논문집
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• 대한조선학회 2006년도 특별논문집
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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.

• 품질경영학회지
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• 제47권3호
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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.

• 대한기계학회논문집B
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• 제24권6호
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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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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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.