• Journal of Magnetics
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• v.19 no.2
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• pp.155-160
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• 2014

The heating produced by the absorption of radiofrequency (RF) has been considered a secondary undesirable effect during MRI procedures. In this work, we have measured the power absorbed by distilled water, glycerol and egg-albumin during NMR and non-NMR experiments. The samples are dielectric and examples of different biological materials. The samples were irradiated using the same RF pulse sequence, whilst the magnetic field strength was the variable to be changed in the experiments. The measurements show a smooth increase of the thermal power as the magnetic field grows due to the magnetoresistive effect in the copper antenna, a coil around the probe, which is directly heating the sample. However, in the cases when the magnetic field was the adequate for the NMR to take place, some anomalies in the expected thermal powers were observed: the thermal power was higher in the cases of water and glycerol, and lower in the case of albumin. An ANOVA test demonstrated that the observed differences between the measured power and the expected power are significant.

• Journal of The Korean Digital Architecture Interior Association
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• v.11 no.1
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• pp.33-42
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• 2011

As the development of construction technology and new materials, building requirements has been varied gadually. Comfortable environment and serviceability of production activity and energy conservation are being dealt with very seriously. Recently localization of engineering technology of Power Plant, however, construction materials and domestic technology are being developed forcingly. According to above topics this thes is going to study roof waterproofing, thermal insulation and evaluate adiabatic performance and evaluation of properties of waterproofing materials and energy conservation. The results of studying and evaluating of roof waterproofing, thermal insulation and adiabatic performance of Power Plant are as follows. 1. Sheet waterproofing method is better than that of asphalt waterproofing method in that adaptability of wearhertight, thermal resistant, contraction and expansion. 2. It is required to replace polyurethane or ethylene used as thermal insulation with rock wool which is noncombustible materials. 3. It is recommended to usd outer insulation method than inner insulation method due to superioty of outer insulation method. Efficiency of insulation materials used in power plant is generally good except perlite mortar used in the power plant(YGN 1-2, GRI 1-2).

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2638-2651
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• 2020

Nozzle corner cracks present at the intersection of reactor pressure vessels (RPVs) and inlet or outlet nozzles have been a persistent problem for a number of years. The fracture analysis of such nozzle corner cracks is very important and critical for the efficient design and assessment of the structural integrity of RPVs. This paper aims to perform an engineering critical assessment of RPVs with nozzle corner cracks subjected to several transients accompanied by pressurized thermal shocks. The critical crack size of the RPV model with nozzle corner cracks under transient loading is evaluated on failure assessment curve. In particular, the influence of cladding on the crack initiation of nozzle corner crack under thermal transients is studied. The influence of primary internal pressure and secondary thermal stress on the stress field at nozzle corner and SIF at crack front is analyzed. Finally, the influence of different crack size and crack shape on the final critical crack size is analyzed.

• Journal of Environmental Impact Assessment
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• v.9 no.1
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• pp.61-74
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• 2000

This study compares the results of environmental impact assessment with the results of post-environmental investigation, using the case of Taean thermal power plant construction. The atmospheric and water qualities were not greatly changed before and after the construction of the power plant. However, the site of the highest concentration predicted by the atmospheric quality modeling in environmental impact assessment was different from that after operation of 4 power plants. There was also a difference in the diffusion range of thermal discharge water between the measured result(1km) and the predicted value(1.5km) with the model. Thus, environmental impact evaluation should be based on long-term (more than a year) environmental monitoring data. For the modeling of atmospheric quality and numerical thermal discharge water diffusion, appropriate models for each plant should be selected and the numerical modeling should be accompanied by computer simulation, wind tunnel test, etc. Moreover, environmental evaluation should focus more on the degree of impact on surroundings than the prediction of changes in surroundings caused by operation of plants.

• Ocean and Polar Research
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• v.35 no.4
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• pp.299-312
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• 2013

This study analyzed the species composition and density of a macrobenthic community according to variations in the thermal discharge volumes of a nuclear power plant before, during, and after the shutdown of the nuclear power plant during two periods. In this study, 369 macrobenthic fauna species were collected, and their mean density was 1,712 ind. $m^{-2}$. The number of species and diversity of macrobenthic fauna decreased with distance from the thermal discharge area, regardless of whether the nuclear plant shutdown or not. Many macrobenthic taxa appeared near the thermal discharge area, but polychaetes species were more prominent in outer areas than at the discharge area. The density of macrobenthic fauna decreased with distance from the thermal discharge area during a plant shutdown in the fall of 2011, but increased, except at two sites, near the discharge area in the winter of 2012. Cluster analysis indicated that the spatial distribution of the macrobenthic community changed in areas near the nuclear power plant after a shutdown period; that is, the station group I, in areas near the nuclear power plant, became narrower after the shutdown, but it recovered to previously occupied areas after the nuclear power plant began operating again. Opportunistic species, such as the polychaetes Lumbrineris longifolia (= Scoletoma longifolia) and Mediomastus californiensis, which were present in high densities near thermal discharge areas, decreased after the shutdown but recovered after the plant re-opened. The number of species and diversity of the macrofauna and the density of dominant species showed a significant correlation with temperature, except in winter periods. The results of this study revealed that changes in the amount of thermal discharge before and after the shutdown of a nuclear power plant could exert an influence on the structure of macrobenthic community within the thermal discharge areas depending on the season.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.3
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• pp.247-256
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• 2000

Basic characteristics of non-thermal plasma process to remove C2H4 and NO have been experimentally investigated with a packed-bed type reactor and an ac power supply. The performance of the non-thermal plasma generated by ac power supply was compared with that of a wire-plate type reactor equipped with a pulsed power supply. The result shows that the non-thermal plasma can be effectively generated with an AC power supply that can be easily fabricated with conventional techniques. In order to understand the basic reaction mechanisms of the non-thermal plasma process, parametric tests for different carrier gases(air and nitrogen) and for different reaction pathways have been performed. The test results show that O3 generated by non-thermal plasma plays an dominant role to oxidize C2H4 and NO over N and O radicals when these pollutant gases are carried by dry air under room temperature condition. Experimental observations, however, indicate that N and O radicals can significantly affect on the removal process of the pollutant gases under certain conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.2
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• pp.96-101
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• 2016

The thermal management of high-power LED components in an assembly structure is crucial for the stable operation and proper luminous function. This study employs numerical tools to determine the optimum thermal design in LEDs with a heat sink consisting of a crevice-type vapor-chamber heat pipe. The effects of the MCPCB are investigated in terms of the substrate thicknesses on which the LEDs are mounted. Further, different placement configurations in a system module are considered. This study found that for a confined area, a power of 40 W/LED is applicable to a high-power package. Furthermore, the thermal conductivity of dielectric layer materials should ideally be greater than 0.9 W/m.K. The temperature conditions of the vapor chamber in a heat pipe greatly affect the thermal performance of the system. At an offset distance of 9.0 mm and a $2^{\circ}C$ increase in the temperature of the heat pipe, the resulting maximum temperature increase is approximately $1.9^{\circ}C$ for each heat dissipation temperature. Finally, at a thermal conductivity of 0.3 W/m.K, it was found that the total thermal resistance changes dramatically. Above 1.2 W/m.K, the resistance change reduces exponentially.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.205-208
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• 2002

Thermal design is required with considering thermal stability to verify the reliability of electric power device with using IGBT. Numerical analysis is performed to analyzed the change in thermal resistance with respect to the various thermal density of heating element. Correlations between thermal resistance and heat generation density are established. With using these correlations, performance curve is composed with respect to the change in thermal resistance of cooling conditions for natural convection and forced convection. Thermal fatigue is occurred at the Inside and outside of IGBT by repeated heat load. The crack is occurred between base plate and ceramic substrate for the inside. When the crack length is 4mm, the failure is occurred. Therefore, Thermal design method considering thermal density, thermal fatigue resistance is presented on this study and it is expected to thermal design with considering life prediction.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.10
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• pp.1757-1762
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• 2007

Recently, the demand for the low cost power conversion equipment is rapidly increased. To develop this three phase voltage source inverter, optimum power conversion equipment to system is designed. The optimum operation method to minimize the power loss also satisfy the life time of the power electronics that is request in the present industry. In this paper, the efficient operating method to change of the acceleration, jerk, and switching frequency in the interval of acceleration is selected to optimize the power loss and life time of the power electronics by using the elevator model. So, we proposed the method that 50[A] rating power electronics is adopted in 9[kW] load.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.301-302
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• 2007

Maximum power consumption was up to 6,228kW in the summer of 2007 due to steady development of industry as well as increased demand of individual. Twenty fossil-Fired Thermal Power Plant for 500MW were underconstructed at present. KEPRI(Korea Electric Power Research Institute) manage 'Development of Advanced Fossil-Fired Thermal Power Generation System' project to construct high efficient power plant of 1000MW capacity for preparing increased demand of power. Design of control logic and data sampling were explained and high efficient control logic was simulated in detail in 'The Development of Next Generation Power Plant Instrument and Control System'(sub-project of 'Development of Advanced Fossil-Fired Thermal Power Generation System' project).