• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.6
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• pp.811-818
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• 2001

The wave characteristics for a non-reacting high-speed liquid jet were investigated using a linear stability theory. In this study, 2-D incompressible viscid momentum equation for a liquid jet was considered, and the effects of injection parameters, such as Weber number, Reynolds number, and density ratio, on the wave characteristics were investigated. With the wavelength obtained from the stability analysis, the atomization model was suggested. The droplet sizes after breakup were determined by the wavelengths of fast growing waves, and the mass of the shed droplets was determined by the breakup time derived by ORouke et al. It was found that in comparison with measurements of diesel fuel spray, the results of calculation had a similar trend of the decrease of overall SMD with the increase of Reynolds number.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1288-1293
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• 2009

This paper discusses about modeling method to simulate a nonlinear behavior like sliding or rocking of two stacked body system under earthquake condition. A double body system design can be an option to reduce seismic response of a component in comparison to a single body system for free standing structures. Therefore, according to the priority of components, the structure is to be designed by proper ratio of partition in their height for improvement of seismic capability and structural integrity. Nonlinear modeling and analysis using simple rigid body and dynamic system has been performed to check the trend in such cases. As a result, one of the two bodies can be chosen to reduce the seismic response from energy absorption of the other one by appropriate application of friction ratios not only in slip-slip condition but in slip-rock condition.

• Journal of the Korean Society of Marine Environment & Safety
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• v.8 no.2
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• pp.61-69
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• 2002

The relatively rapid rising trend of crime rates in marine situations leads to social concerns in Korea. This study reviews some theoretical backgrounds of the economics of crime and applies econometric models to Korean marine crimes. This research finds that there is a negative relationship between marine crime rates and unemployment rates and a positive relationship between the price level and marine crimes in Korea. The other finding results are that unemployment elasticities are higher in the 1980s and price elasticities are higher in th 1990s in comparison with the results of the other periods. This findings are incompatible with the previous theoretical researches in advanced countries. These findings show that In rapidly growing economy, marine crime occurrence is proportional to marine economic activity frequency. This result may reflect that marine crimes are different from land crimes.

• Journal of Magnetics
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• v.20 no.4
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• pp.421-426
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• 2015

This paper presents a practical method for estimation of average temperature in the permanent magnet (PM) of electric machine by using finite element analysis (FEA) and dynamo load experiment. First of all, the temperature effect of PM to the torque has been employed by FEA in order to evaluate the Temperature-Torque characteristic curve. The 1st order polynomial equation which is torque attenuation coefficient is derived by the FEA result of the Temperature-Torque curve. Next, torque saturation test with constant current condition is performed by dynamo load experiment. Then, the temperature trend can be estimated by adding the initial starting temperature using the torque attenuation coefficient and torque saturation curve. Lastly, estimated temperature is validated by infrared thermometer which measures temperature of PM surface. The comparison between the estimated result and experimental result gives a good agreement within a deviation of maximum $8^{\circ}C$.

• Hwankyungkyoyuk
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• v.22 no.4
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• pp.111-133
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• 2009

To understand the research trend of environmental education(EE) during last two decades, we analyzed a total of 801 research papers published from 1990 to 2008, 418 research papers from "Hwankyungkyouk" and 393 research papers from "The Journal of Environmental Education(JEE)", respectively. The majority of the authors in both journals majored in EE, followed by authors of science education major in "Hwankyungkyouk" and authors of social science major in JEE. In both journals, more researches were data-collected by quantitative method rather than qualitative method. In particular, the ratio of researches by qualitative method have been dramatically increased since the mid 1990s. The significance test was less used in Korean EE researches than those in JEE. In both journals, more EE researches for elementary and secondary school students were accomplished, which tended to be more salient in Korea. The result of the analysis of 119 EE programs in both journals proposed that EE program needs to be developed more diversely in content as well as in educational method.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.27-32
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• 1997

It was fond that the compressive and flexural strength of recycled concrete was decreased with increasing the content of recycled aggregate and the early compressive strength was also decreased with increasing Fly Ash level. In comparison with recycled concretes producing various sources, the trend were similar to those shown above, but the differences were minor. the development of Flexural strength in both concretes was similar, but the recycled concrete is lower in the ratio of flexural strength and compressive strength. The drying shrinkage of recycled concrete is increased with increasing the amount of recycled aggregate, particularly the maximum differences were reached between at 2 and 3 weeks.

• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.57-66
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• 2000

The truss analogy for the analysis of beam-columns subjected of shear and flexure is limited by the contribution of transverse and longitudinal steel and diagonal concrete compression struts. However, it should be noted that even though the behavior of reinforced concrete beam-columns after cracking can be modeled with the truss analogy, they are not perfect trusses but still structural elements with a measure of continuity provided by a diagonal tension field. The mere notion of compression field denotes that there should be some tension field coexisting perpendicularly to it. The compression field is assumed to form parallel to the crack plane that forms under combined flexure and shear. Therefore, the concrete tension field may be defined as a mechanism existing across the crack and resisting crack opening. In this paper, the effect of concrete tensile properties on the shear strength and stiffness of reinforced concrete beam-columns is discussed using the Gauss two-point truss model. The theoretical predictions are validated against the experimental observations. Although the agreement is not perfect, the comparison shows the correct trend in degradation as the inelasticity increases.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.657-661
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• 2009

In this study, rheological properties of cement pastes containing ground Finex-slag (4000, 6000, 7000 c$m^2$/g) were investigated bymini-flow test and coaxial cylinder viscometer. And also blast furnace slag(4000, 6000, 7000 c$m^2$/g) were used for comparison. According to the experimental results, Finex-slag and blast furnace slag showed very similar trend in the rheological properties of the cement pastes. The fluidity of cement pastes blended Finex-slag and blast furnace slag powder were improved by high replacement ratio. In the relationship of plastic viscosity and yield stress appeared the tendency of the proportion greatly. And in the relationship of plastic viscosity, yield stress and mini-flow appeared the tendency of the inverse proportion.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2004.11a
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• pp.399-403
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• 2004

As the housing market is changing, there's a trend that the brand marketing through the TV-CM is increasing. Thus, this study purposes to identify the characteristics and the limit of the marketing on the housing market by analyzing the elements of marketing on TV-CM in the 2000's and comparing the representative business enterprises with each other. In the case of television advertisement, it is dominated by the emotional advertisement which is sensitive and image-oriented than the rational one. In addition, 1 pointed out some problems resulted from the transitional feature of the television advertisement and the gap between the real apartment and its brand image appeared on the advertisement, then I will present corresponding solutions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.05a
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• pp.43-45
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• 1988

Four W/Cu system(60wt%W-40wt%Cu, -0.lwt%Ni, -0.5wt%Ni, -0.lwt%C) and four WC/Cu system(60wt%WC-40wt%Cu, -0.lwt%Ni, -0.5wt%Ni, 0.lwt%C) electrical contacts were prepared by a press-sinter-infiltration process to compare with their properties. Hardness and electrical conductivity are proportional to the refractory metal(W or WC) properties and showed the effect of additives. Arc erosion trend of switch test is changed by current level. High currant test at 1kA showed a different crack formation pattern and erosion mode between W/Cu system and WC/Cu system contacts.