• Nuclear Engineering and Technology
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• v.39 no.4
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• pp.299-312
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• 2007

The program on thermal-hydraulic evaluation by testing and analysis (THETA) for the development and licensing of the new design features in the APR1400 (Advanced Power Reactor-1400) is briefly introduced with a presentation on the research motivation and typical results of the separate effect tests and analyses of the major design features. The first part deals with multi-dimensional phenomena related to the safety analysis of the APR1400. One research area is related to the multidimensional behavior of the safety injection (SI) water in a reactor pressure vessel downcomer that uses a direct vessel injection type of SI system. The other area is associated with the condensation of steam jets and the resultant thermal mixing in a water pool; these phenomena are relevant to the depressurization of a reactor coolant system (RCS). The second part describes our efforts to develop new components for safety enhancements, such as a fluidic device as a passive SI flow controller and a sparger to depressurize the RCS. This work contributes to an understanding of the new thermal-hydraulic phenomena that are relevant to advanced reactor system designs; it also improves the prediction capabilities of analysis tools for multi-dimensional flow behavior, especially in complicated geometries.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.214-215
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• 2009

• Geomechanics and Engineering
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• v.6 no.1
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• pp.79-98
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• 2014

This paper presents an experimental and numerical study on the evaluation of a thermal response test using a precast high-strength concrete (PHC) energy pile and a closed vertical system with W-type ground heat exchangers (GHEs). Field thermal response tests (TRTs) were conducted on a PHC energy pile and on a general vertical GHE installed in a multiple layered soil ground. The equivalent ground thermal conductivity was determined by using the results from TRTs. A simple analytical solution is suggested in this research to derive an equivalent ground thermal conductivity of the multilayered soils for vertically buried GHEs. The PHC energy pile and general vertical system were numerically modeled using a three dimensional finite element method to compare the results with TRTs'. Borehole thermal resistance values were also obtained from the numerical results, and they were compared with various analytical solutions. Additionally, the effect of ground thermal conductivity on the borehole thermal resistance was analyzed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.17-20
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• 1998

Thermal behavior of Flow Pattern Defect (FPD) and Large Pit (LP) in Czochralski Silicon crystals was investigated by applying high temperature ($\geq$1100$^{\circ}C$) annealing and non-agitation Secco etching. For evaluation of the effect of LP upon device performance / yield, DRAM and ASIC devices were fabricated. The results indicate that high temperature annealing generates LPs whereas it decreases FPD density drastically, and LP does not have detrimental effects on the performance /

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.205-208
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• 2012

In this study, the thermal behavior and combustion characteristics of different ranks of coals and their blends were investigated to obtain information necessary for the evaluation of the co-processing of blends with low-rank coals. Thermogravimetric analysis(TGA) and differential thermal analysis(DTA) were carried out at different temperature from ambient temperature to $800^{\circ}C$, and a laboratory-scale pulverized coal combustion burner was used with coal feeing rate of $1.04{\times}10^{-4}kg/s$.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.46-53
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• 2011

The risk assessment of thermal behavior and runaway reaction cased by an exothermic batch process in manufacture of the vinyl acetate resin are described in the present paper. The aim of the study was to evaluate the risk of runaway reaction with operating parameters such as a reaction inhibitor, reaction temperature and a mount of methanol charged in the vinyl acetate polymerization process. The experiments were performed by a sort of calorimetry with the Multimax reactor system as a screening tool to investigate runaway reaction. From the experimental results, it was found that we could occur the auto acceleration for reaction of raw materials with operating parameters over $65^{\circ}C$ of reaction temperature in the vinyl acetate polymerization process.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.198.2-198.2
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• 2016

Reactive oxygen and nitrogen species (RONS) can be generated by using non-thermal atmospheric pressure plasma jet which have profound biomedical applications [1, 2]. In this work, reactive oxygen species like hydroxyl radical (OH) are generated by using non-thermal direct plasma jet above water surface using Ar gas and their properties have been studied using ultraviolet absorption spectroscopy. OH radicals are found to be generated simultaneously with the discharge current with concentration of $2.7{\times}1015/cm3$ at 7mm above water surface while their persistence time have been measured to be $2.8{\mu}S$. In addition, it has been shown that plasma initiated ultraviolets play a major role to generate RONS inside water. Further works are going on to measure the temporal behavior of OH and $O2^*-$.

• Nuclear Engineering and Technology
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• v.41 no.6
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• pp.775-784
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• 2009

This paper summarizes the tests performed in the ATLAS facility during its first two years of operation (2007${\sim}$2008). Two categories of tests have been performed successfully: (a) the reflood phase of the large-break loss-of-coolant accidents in a cold leg, and (b) the breaks in one of four direct vessel injection lines. Those tests contributed to understanding the unique thermal-hydraulic behavior, resolving the safety-related concerns and providing an evaluation of the safety analysis codes and methodology for the advanced pressurized water reactor, APR1400. Several important and interesting phenomena have been observed during the tests. In most cases, the ATLAS shows reasonable accident characteristics and conservative results compared with those predicted by one-dimensional safety analysis codes. A wide variety of small-break LOCA tests will be performed in 2009.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.1
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• pp.44-51
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• 2005

Material degradation is a multibillion-dollar problem which affects all the industries amongst others. The last decades have seen the development of newer and more effective techniques such as Focused-ion beam(FIB), Transmission electron microscopy(TEM), Secondary-ion mass spectroscopy(SIMS), auger electron spectroscopy(AES), X-ray Photoelectron spectroscopy(XPS) , Electrochemical impedance spectroscopy(EIS), Photo- stimulated luminescence spectroscopy(PSLS), etc. to study various forms of material degradation. These techniques are now used routinely to obtain information on the chemical state, depth profiling, composition, stress state, etc. to understand the degradation behavior. This paper describes the use of these techniques specifically applied to materials degradation and failure analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.275-279
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• 1996

In this study, the effect of external restraint on the thermal stresses and thermal cracking mode in mass concrete are analysed using the two major factors affecting external restraint such as the ratio of width go height of the placed structure (L/H) and the elastic modulus of base structure (E). For this parametric study, many cases with different values of L/H and Er are analysed by the FEM program and the co-relationship of the those major factors is examined. To evaluate the effect of external restraint on the thermal behavior of placing structure, internal restraint stress caused by temperature difference is subtracted from total thermal stress. In the case of small value of L/H or Er, it shows as internally restricted mode indicating maximum tensile stress in surface at early age, and the external restraint makes the possibility of thermal cracking higher. However, in the case of the large values of L/H and Er, the crack index at center is smaller than at surface due to the effect of external restraint. Thus, the initial location of the thermal crack is shifted from the surface to the center and the resulting crack is formed at later age.