• Structural Engineering and Mechanics
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• v.54 no.1
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• pp.169-188
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• 2015

This study presents the effects of the spatial variation of ground motions in a hard rock site on the seismic responses of a base-isolated nuclear power plant (BI-NPP). Three structural models were studied for the BI-NPP supported by different number of lead rubber bearing (LRB) base isolators with different base mat dimensions. The seismic responses of the BI-NPP were analyzed and investigated under the uniform and spatial varying excitation of El Centro ground motion. In addition, the rotational degrees of freedom (DOFs) of the base mat nodes were taken to consider the flexural behavior of the base mat on the seismic responses under both uniform and spatial varying excitation. Finally, the seismic response results for all the analysis cases of the BI-NPP were investigated in terms of the vibration periods and mode shapes, lateral displacements, and base shear forces. The analysis results indicate that: (1) considering the flexural behavior of the base mat has a negligible effect on the lateral displacements of base isolators regardless of the number of the isolators or the type of excitation used; (2) considering the spatial variation of ground motions has a substantial influence on the lateral displacements of base isolators and the NPP stick model; (3) the ground motion spatial variation effect is more prominent on lateral displacements than base shear forces, particularly with increasing numbers of base isolators and neglecting flexural behavior of the base mat.

• Bulletin of the Korean Mathematical Society
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• v.58 no.6
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• pp.1377-1385
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• 2021

In this paper, we consider a general number system with a base m in order to determine if a positive integer x is prime. We show that the base m providing the most efficient test is the primorial p_n# when p_n# < x < p_n+1# and establish a necessary and sufficient condition for x in between consecutive primorials to be determined as a prime number.

• Steel and Composite Structures
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• v.21 no.2
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• pp.357-371
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• 2016

Column base connections are critical components in steel structures because they transfer axial forces, shear forces and moments to the foundation. Exposed column bases are quite commonly used in low- to medium-rise buildings. To investigate shear transfer in exposed column base plates, four large scale specimens were subjected to a combination of axial load (compression or tension) and lateral shear deformations. The main parameters examined experimentally include the number of anchor rod, arrangement of anchor rod, type of lateral loading, and axial force ratio. It is observed that the shear resisting mechanism of exposed column base changed as the axial force changed. When the axial force is in compression, the resisting mechanism is rotation type, and the shear force will be resisted by friction force between base plate and mortar layer. The specimens could sustain inelastic deformation with minimal strength deterioration up to column rotation angle of 3%. The moment resistance and energy dissipation will be increased as the number of anchor rods increased. Moreover, moment resistance could be further increased if the anchor rods were arranged in details. When the axial force is in tension, the resisting mechanism is slip type, and the shear force will be resisted by the anchor rods. And the shear resistance was reduced significantly when the axial force was changed from compression to tension. The test results indicated that the current design approach could estimate the moment resistance within reasonable acceptance, but overestimate the shear resistance of exposed column base.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.6
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• pp.717-729
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• 1999

Although many studies on the cytotoxicity of the dental cast base metal alloys and their components have been carried out, the results are rather conflicting because of the different type of cells used and the various experimental procedures taken. Recently a number of scientists have claimed that it would be preferable to focus on the use of cells from relevant specific location of the human bodies. Consequently, the primary cultured oral keratinocyte derived from oral mucous along with nickel chloride and several of widely used dental cast base metal alloys(two Ni-Cr alloys and one Co-Cr alloy)in domestic were selected for this study, from which 1) The amounts of released metal ions were determined using atomic absorption spectrometry, 2) The cytotoxicity of nickel chloride and dental cast base metal alloys was evaluated via MTT assay, and finally, 3) The amounts of released metal ions and the cytotoxicity of nickel chloride were correlated with the cytotoxicity of dental cast base metal alloys And, the results were summarized as follows; 1. Nickel ion from Ni-Cr alloys and Cobalt ion from Co-Cr alloys resulted in maximum releasing rate during first 2h hours, followed by a decrease in releasing rate with time. Chromium ion were found to be minimal in all alloys. 2. In cytotoxic test. with $40{\mu}M,\;80{\mu}M$ of nickel chloride, there were observed an increase in the relative cell number compared to control samples after 24 hours. With $160{\mu}M$, there was found to be no difference in the relative cell number with control, except that 48 hour showed a increase in relative cell number. With $320{\mu}M$, the relative cell number remained constant and decreased after 48 hours, and with $640{\mu}M$, a continuing decrease in relative cell number was observed throughout test period. 3 The sensitivity of primary cultured oral epithelium to nickel was lower compared to the cells used in other studies. 4. CB-80 Soft and Regalloy showed no cytotoxicity to primary cultured oral epithelium and New crown resulted in a slight cytotoxicity. In conclusion, it was shown that the primary cultured oral keratinocytes could be applied successfully as testing cells in cytotoxicity test. Futhermore, the dental cast base metal alloys used in this study were found to be biocompatible.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.11
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• pp.849-859
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• 2020

The semi-empirical equation and commercial computational tool were used to predict the base drag of a guided missile with free-stream Mach numbers and chamber pressures, and the results were generally agree each other. Differences in flow characteristics and base drags were observed with over/under expansion conditions by the nozzle. Under the over-expansion condition, the base pressure decreased as the expansion fan was generated at upper region of the base, and base pressure decreased further with increasing free-stream Mach number as the expansion becomes strong. Under the under-expansion conditions, a shock wave was generated around the base by the influence of the nozzle flow, which increased the base pressure, and the effect increased as the chamber pressure increased. Under the same chamber pressure condition, as the free-stream Mach number increases, the characteristic that the base pressure decreases as the shock wave generated at the base moves downstream was observed.

• Proceedings of the KIEE Conference
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• 2002.11a
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• pp.141-144
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• 2002

The method of the analysis of the base Gummel number of the PNP BJT(Bipolar Junction Transistor) for integrated circuits based upon the semiconductor physics is proposed and the method of calculating the doping profile of the base region using process conditions is presented. The transistor saturation current obtained from the proposed method of PNP BJT using 20V and 30V process shows an averaged relative error of 6.7% compared with the measured data.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.90-96
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• 2014

IEEE802.15.4 that is a standard for sensor networks is mainly used the wireless personal area networks such as ZigBee networks and it features low-power, low-speed data communication. However, recently research for interworking sensor network based voice communication and Session Initiation Protocol (SIP) for long-range, multi-user support has been actively conducted. In this paper, we designed a integrated base station based existing systems for interworking sensor networks based voice communication and SIP. We measured number of packet and delay according to increase the number of users to evaluate the performance of designed Base Station.

• MALSORI
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• no.66
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• pp.21-39
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• 2008

The purpose of this study is to analyze the intonational slope characteristics of the Korean news utterances. Prosodic phrases were analyzed in terms of the K-ToBI labeling system. In addition, the change of intonation contour that occurs throughout the sentences was discussed in terms of types of media and gender. Results showed that the overall declination of the intonation contour of radio and male revealed a gentler slope than that of TV and female, respectively. While the regression of the top line slope showed male's higher $R^2$ with the number of words, the base line slope of the radio and female was proved to be highly influenced from the number of syllables, words, and prosodic phrases. A lot more independent variables statistically affected to the base line slope. This means that the base line slope was strongly related to the variables, the top line slope, otherwise, could be more freely fluctuated due to the light correlation with them.

• Journal of the military operations research society of Korea
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• v.16 no.2
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• pp.96-104
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• 1990

This paper concerns the problem of deciding the rational spare inventory levels for efficient use of a limited defence budget and, at the same time, for enhancing the operation rate of equipement/weapons in the army. The system we are concerned has a finite number of repairmen at each base and the depot. After repair job has completed, the repaired items are returned to the base where they have originated. For the system, we identify the distribution of the total number of failed items which belong to a base and develope a method to find spare inventory levels of repairable items at each base to satisfy a specified minimum fill rate.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.45-54
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• 2012

Optimization of the asymmetric trapezoidal fin with various upper lateral surface slope is made using a two-dimensional analytic method. For the fixed fin base height, the optimum heat loss, fin length and effectiveness are represented as inner fluid convection characteristic number, fin base thickness, fin base height, fin shape factor and ambient convection characteristic number. For this optimum procedure, the optimum heat loss is defined as 95% of the maximum heat loss from the fin. One of the results shows that optimum heat loss and effectiveness seems independent of the fin shape factor while optimum fin length decreases almost linearly as the fin shape factor increases.