• Nuclear Engineering and Technology
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• v.51 no.4
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• pp.1008-1016
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• 2019

In the SG (steam generator) of PWR (pressurized water reactor) for a nuclear plant, hundreds of U-shaped tubes are used for the heat exchanger system. They interact with primary pressurized cooling water flow, generating flow-induced vibration in the secondary flow region. A simplified U-tube model is proposed in this study to apply for experiment and its counterpart computation. Using the commercial code, ANSYS-CFX, we first verified the Moody chart, comparing the straight pipe theory with the results derived from CFD (computational fluid dynamics) analysis. Considering the virtual mass of fluid, we computed the major modes with the low natural frequencies through the comparison with impact hammer test, and then investigated the effect of pump flow in the frequency domain using FFT (fast Fourier transform) analysis of the experimental data. Using two-way fluid-structure interaction module in the CFD code, we studied the influence on mean flow rate to generate the displacement data. A feasible CFD method has been setup in this research that could be applied potentially in the field of nuclear thermal-hydraulics.

• International Journal of Fluid Machinery and Systems
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• v.6 no.3
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• pp.160-169
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• 2013

Two-stage turbocharging is an important way to raise engine power density, to realize energy saving and emission reducing. At present, turbine matching of two-stage turbocharger is based on MAP of turbine. The matching method does not take the effect of turbines' interaction into consideration, assuming that flow at high pressure turbine outlet and low pressure turbine inlet is uniform. Actually, there is swirl flow at outlet of high pressure turbine, and the swirl flow will influence performance of low pressure turbine which influencing performance of engine further. Three-dimension models of turbines with two-stage turbocharger were built in this paper. Based on the turbine models, mechanism of swirl flow at high pressure turbine outlet influencing low pressure turbine performance was studied and a two-stage radial counter-rotation turbine system was raised. Mechanisms of the influence of counter-rotation turbine system acting on low-pressure turbine were studied using simulation method. The research result proved that in condition of small turbine flow rate corresponding to engine low-speed working condition, counter-rotation turbine system can effectively decrease the influence of swirl flow at high pressure turbine outlet imposing on low pressure turbine and increases efficiency of the low-pressure turbine, furthermore increases the low-speed performance of the engine.

• Journal of the Korean institute of surface engineering
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• v.7 no.1
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• pp.5-12
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• 1974

The interaction energy of water molecule over the surfaces of basal planes of silver iodide has been calculated , assuming 1-4-6--12 type potentials between the gas molecule and lattice ions in the silver iodide lattice. The heat of adsorption ranges from 12.25 to 12.75 kcal /mole at low coverage which is around the level of the latent heat of sublimaton of water.

• Journal of Korean Elementary Science Education
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• v.26 no.4
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• pp.395-406
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• 2007

The purpose of this study was to investigate the characteristics of 2nd grade students' interaction in the classification activities of LTTS. For the purposes of this study, three heterogeneous groups, chosen by cognitive level, were selected. The students' interactions were audio/video taped and classified as either cognitive or affective interaction. The results of this study are as follows. In the cognitive interactions, the frequency and quality of the functions of 'questions' and 'making suggestions' were higher than those of 'Responses' and 'Receiving opinions'. In the affective interactions, the frequency of 'induction' and 'dissatisfaction' was higher than that of the other types. The frequency and quality of interactions of students in both the early and mid concrete stage were higher than those of students in the transitional stage. Qualitatively higher-level interactions such as 'making suggestions' and positive interactions such as 'induction' to induce students who were passive in activities were made by the students at higher cognitive levels. However, the low-level of interaction in suggesting their opinion to the constituent's suggestion and 'dissatisfaction' with student in transition period who were passive in activity influenced group working negatively.

• Journal of The Korean Association For Science Education
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• v.32 no.8
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• pp.1269-1280
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• 2012

The purpose of this study is to analyze the verbal interaction during elementary students' hypothesis generation learning. For this study, 32 6th graders were selected and were assorted into heterogeneous small-groups by achievement levels. The topics of hypothesis generation learning were developed by analyzing the current elementary school curriculum. Each group's verbal interactions were audio/video taped and transcribed. After coding the protocol and having student retrospective interview, types and frequency of verbal interaction were analyzed. The frequency of verbal interaction during observation was highest and that of questioning situation identification was lowest. Regarding to the quality of verbal interactions, low level interactions were significantly frequent during observation. On the other hand, hypothetical explicans generation revealed high frequency of high level interactions. The results revealed that elementary students can make high level verbal interactions through hypothesis generation learning.

• Journal of Power System Engineering
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• v.12 no.6
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• pp.29-35
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• 2008

This study is conducted to provide the proper analysis method to evaluate the stability of a container crane under wind load. Two analysis method, namely structure analysis and fluid-structure interaction, are adopted to evaluate the stability of a container crane in this investigation. To evaluate the effect of wind load on the stability of the crane, 50-ton class container crane widely used in container terminals is adopted for analysis model and 19-values are considered for wind direction as design parameter. We conduct structure analysis and fluid-structure interaction for a container crane with respect to the wind direction using ANSYS and CFX. Then we compare the uplift forces yielded from two analysis with it yielded from wind tunnel test. The results are as follows: 1) A correlation coefficient between structure analysis and wind tunnel test is lower than 0.65(as $0.29{\sim}0.57$), but between fluid-structure interaction and wind tunnel test is higher than 0.65(as $0.78{\sim}0.86$). 2) There is low correlation between structure analysis and wind tunnel test but very high correlation between fluid-structure interaction and wind tunnel test.

• Korean Journal of Computational Design and Engineering
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• v.19 no.4
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• pp.332-339
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• 2014

This paper presents on the development of wheel-terrain interaction device using low-priced sensors, which will be used to predict the drawbar pull and optimal slip of off-road vehicle in real time. The essential variables obtained in the device to predict the mobility of vehicles are determined based on semi-empirical model describing the wheel-terrain interaction. Using the developed device, the experiments about the wheel-terrain interaction were performed on the soil of the Jumunjin standard sand, which yielded dynamic weight, motor driving torque, drawbar pull, and sinkage with respect to wheel slip ratio. Finally, the repeatability of the measured data are verified through repeating the experiments three times on the same condition.

• Fashion & Textile Research Journal
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• v.8 no.3
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• pp.286-294
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• 2006

The purpose of this study was to identify the effect of marketing activities to apparel brand community on interaction of the community. Subjects of 317 members for 9 selected apparel communities responded the questionnaire in the home-page or in the attached file. Data were analyzed by exploratory factor analysis, one-way ANOVA, scheffe-test. The results were as follows: Significant differences among three community groups classified based on the levels of interactions(interaction of company to members and interaction among members) were found in several types of marketing activities(award to activities, added services, conveyance of community's purpose and acceptance of negative responses) to apparel brand community. These types of marketing activities were operated in communities with high level interactions higher than in communities with low level interactions. Therefore, marketers need to operate these types of community marketing activities to increase interactions which can contribute members' satisfaction of interest, transaction and relationship needs through apparel brand online community.

• Journal of the Korean Society of Food Culture
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• v.22 no.2
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• pp.218-224
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• 2007

The purpose of this study was to measure the effects of value and satisfaction moderating the relationship between foodservice quality and behavioral intention. A total of 273 questionnaires were completed. Moderated regression analysis was used to measure the relationships between variables. Results of the study demonstrated that the analysis result for the data also indicated excellent model fit. The main effects of foodservice quality, value, and satisfaction on behavioral intention were statistically significant. The interaction effect of quality and satisfaction on behavioral intention was not statistically significant. The interaction effect of value and satisfaction on behavioral intention was not statistically significant. As expected, the interaction effect of quality and value on behavioral intention was statistically significant. Moreover, foodservice quality on behavioral intention was statistically significant at all levels of value and satisfaction, except for when value level was low, and satisfaction level was high. The results of this study indicated that restaurant marketers should attach importance to the interaction effect of service quality and customer value to understand the elements of market demand and customer loyalty.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.483-488
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• 2002

Noise has become an environmental pollution that affects most peoples' health, comfort or general well being. there are many sources of noise, but one of them clearly dominates road traffic noise. It has traditionally been associated with engine and exhaust noise of vehicles. However the emission and propagation of noise from these sources were partly reduced, while at the same time the noise emission from the tire/road interaction on a relative scale became more and more prominent Generally, Portland cement concrete(PCC) pavements have the advantage of durability and superior surface friction when compared to most dense-graded asphalt. However, It is known that PCC pavements create more noise than asphaltic surfaces due to the noise from interaction of tire and pavement surface. Therefore, recent research has shown some new concrete pavement textures to be worth further examination. So in this paper, we considered the 9 types of low noise concrete pavements to evaluate tire/pavement noise.