• Research in Mathematical Education
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• v.6 no.1
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• pp.29-38
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• 2002

The purpose of this paper was to examine early numerical representations between American and Korean children. Fifty-five first graders (35 Korean and 20 American) participated in the study. According to the findings of the current study, the author concluded that the Korean children had a stronger conception of base ten representations of numbers than that of the American children. The Korean children used various strategic reasoning such as decomposition and recomposition on the basis of base 10 structure to solve addition and subtraction problems effectively. However, the author cannot conclude that language differences would be the largest factor that would make Korean children sapient in the representations of base ten structures.

• Journal of the Korean Society for Heat Treatment
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• v.16 no.6
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• pp.341-348
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• 2003

Superalloys which can be devided into three categohes, i.e. Ni-base, Co-base, and Fe-base alloys are widely used for high temperature applications. Since superalloys contain many alloying elements and precipitates, its chemistry and processing parameters need to be carefully designed. In this review, current state-of-the art in the superalloy technologies is described with special attention to the heat-treatment for the control of the microstructures and mechanical properties.

• Steel and Composite Structures
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• v.17 no.4
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• pp.535-548
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• 2014

In this paper, the exact closed-form solutions for torsional analysis of heterogeneous magnetostrictive circular cylinder are derived. The cylinder is subjected to the action of a magnetic field produced by a constant longitudinal current density. It is also acted upon by a particular kind of shearing stress at its upper base. The rigidity of the cylinder is graded through its axial direction from one material at the lower base to another material at the upper base. The distributions of circumferential displacement and shear stresses are presented through the radial and axial directions of the cylinder. The influence of the magnetostrictive parameter is discussed. The effects of additional parameters are investigated.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.10
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• pp.5599-5608
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• 2013

With the high morbidity and mortality caused by cancer, finding new and more effective anti-cancer drugs is very urgent. In current research, biotransformation plays a vital role in the research and development of cancer drugs and has obtained some achievements. In this review, we have summarized four applications as follows: to exploit novel anti-cancer drugs, to improve existing anti-cancer drugs, to broaden limited anti-cancer drug resources and to investigate correlative mechanisms. Three different groups of important anti-cancer compounds were assessed to clarify the current practical applications of biotransformation in the development of anti-cancer drugs.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1924-1934
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• 2023

In this study, the probabilistic fatigue life model for Ni-base alloys was developed based on the Weibull distribution using statistical analysis of fatigue data reported in NUREG/CR-6909 and the new fatigue data of Alloy 52M/152 and 82/182. The developed Weibull model can consider right-censored data (i.e., non-failed data) and quantify the improved safety (or reliability) based on the level of failure probability. The overall margin in the current fatigue design limit model (ASME design curve + NUREG/CR-6909 F_en model) is similar to that of the Weibull model with a cumulative failure probability of approximately 2.5%. The margin in the current fatigue design limit model demonstrated inconsistencies for the Ni-base alloy weld data, whereas the Weibull model showed a consistent margin. Therefore, the Weibull model can systematically mitigate the excessive safety margin.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.11
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• pp.40-47
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• 1993

In this paper, a method for analyzing coaxial collinear antenna for base station of mobile communications using the moment method and the transmission line theory is presented. The excited voltages at the junctions between elements are expressed as the matrix with transmission parameters and these voltages are applied to the integral equation for calculating current distribution. Here, the current distributions, input admittances, radiation patterns and gains are calculated. Calculated values of the current distributions and the input admittances show good agreement with measured values. In case of beamtilted collinear antenna, radiation pattern is simialar to measured result except side lobe.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.401-407
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• 2004

This study is on the constant-current stress corrosion test related to the load stress in welded zone and non-welded zone of high tensile strength steel for natural gas transmission. The surface corrosion pattern of the welded zone of API 5L-X65 specimens for natural gas transmission showed global corrosion and narrow pitting, and the pitting was increased by increasing the load stress. Initially, the average relative electrode potential and the average relative current of the high tensile strength steel for natural gas transmission specimens was decreased suddenly, and the average relative electrode potential was higher and the average relative current was lower in welded zone than base metal. and the average relative electrode potential was decreased by increasing the load stress, and the average relative current was somewhat increased by increasing the load stress. The corrosion rate was less in welded zone than base metal, and the corrosion rate was decreased by increasing the load stress.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.210-221
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• 2009

A new foundation type which is called Top-Base method has been used frequently in engineering practices in Korea. In this study, the settlement behavior of concrete Top-Base foundation on soft ground is investigated since the consolidation settlement of the embedding depth and the effect of footing dimensions are not included in current Korean criterion (2007). To obtain detailed information, the model tests of the Top-Base foundation are performed using the PLAXIS 3D finite element analysis. It is shown that in-situ measurements and finite element analysis of the behavior of foundations indicate that consolidation settlement is reduced up and bearing capacity of the foundation increases up to 50%~100%, compared to the primary non-treated ground. Based on this study, it is found that the Top-Base foundation prevents the lateral deformation of soft ground and reduces its negative dilatancy to the surface settlement, and that the foundation creates rather uniform stress distribution under it to increase its bearing capacity. It is also found that the total settlement of Top-Base foundation was highly dependent on the consolidation settlement and footing configurations.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.10a
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• pp.167-175
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• 2000

Seismic analyses of structures can`t be performed without considering the effect of soil-structure interaction and seismic responses of a structure taking into account the stiffnesses of a foundation-soil system show a significant difference from those with a rigid base. However, current seismic analyses of apartment building structures were carried out assuming a rigid base and ignoring the characteristics of a foundation and the properties of the underlying soil. In this study, seismic analyses of apartment buildings of a particular wall-slab structural type were carried out comparing seismic response spectra of a flexible base with those of a rigid base and UBC-97. Wall-slab type low-rise or mid-height apartment buildings built on the deep soil layer showed a rigid body motion with the reduced seismic responses due to the base isolation effect, indicating that it is too safe but uneconomical to utilize the design spectra of UBC-97 for the seismic analysis of a wall-slab type apartment buildings due to the too conservative design.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.2
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• pp.1-4
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• 2000

We presented a method for extracting the base resistance r/sun bb/ based on analysis of the equivalent noise circuit for common collector. Measurements were conducted on devices with poly-emitter structure fabricated by BiCMOS process. Base resistance measurements have been performed for different base currents and structure. For low base current it is shown that the experimental data agree with theoretical expectations.