• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.385-392
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• 2014

The isolators have been generally used to reduce a seismic force. If the isolators apply to the nuclear power plants(NPPs), the durability and capacity for the structures and equipments should be ensured during the life time. In this study, the long-term behavior of isolated NPPs was analyzed for ensuring the seismic safety. The properties of isolator due to the age-related degradation were analyzed. And the seismic behavior of isolated buildings was analyzed by considering the aging of rubber bearings in different temperature environments. According to the analysis results, the natural frequency of structures was increased with time. But the maximum acceleration and maximum displacement of isolated structures have not changed significantly. Although the damaged of structure did not occurred by aging of isolators, it was presented that the spectral acceleration at the target frequency of isolated structure increased with the temperature. Therefore the isolators in the isolated buildings should be carefully designed and manufactured considering the temperature-dependancy of rubber material.

• Structural Engineering and Mechanics
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• v.59 no.4
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• pp.719-737
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• 2016

The present study investigated the earthquake behavior of R/C structures considering the vertical earthquake motion with the help of a comparative study. For this aim, the linear time-history analyses of a high-rise R/C structure designed according to TSC-2007 requirements were conducted including and excluding the vertical earthquake motion. Earthquake records used in the analyses were selected based on the ratio of vertical peak acceleration to horizontal peak acceleration (V/H). The frequency-domain analyses of the earthquake records were also performed to compare the dominant frequency of the records with that of the structure. Based on the results obtained from the time-history analyses under the earthquake loading with (H+V) and without the vertical earthquake motion (H), the value of the overturning moment and the top-story vertical displacement were found to relatively increase when considering the vertical earthquake motion. The base shear force was also affected by this motion; however, its increase was lower compared to the overturning moment and the top-story vertical displacement. The other two parameters, the top-story lateral displacement and the top-story rotation angle, barely changed under H and H+V loading cases. Modal damping ratios and their variations in horizontal and vertical directions were also estimated using response acceleration records. No significant change in the horizontal damping ratio was observed whereas the vertical modal damping ratio noticeably increased under H+V loading. The results obtained from this study indicate that the desired structural earthquake performance cannot be provided under H+V loading due to the excessive increase in the overturning moment, and that the vertical damping ratio should be estimated considering the vertical earthquake motion.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.2
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• pp.180-185
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• 2011

The TPMS(Tire Pressure Monitoring System) is an electronic system designed to display the air pressure inside the pneumatic tires and report real-time tire-pressure information to the driver of the vehicle, either via a gange, a pictogram display, or a simple low-pressure warning light. Although the data measured by TPMS sensor is transmitted to internal signal processer in a vehicle through wireless communication, the receiver may suffers from various interferences such as amateur radio station, RFID(Radio-Frequency IDentification) for controlling container, RKE(Remote Keyless Entry) signal, and so on. In this paper, we consider beamforming technology to suppress various high-power interference signals for the TPMS wireless communications. Also, we propose the proper data structure and antenna arrangement for the beamformer inside the vehicle. The performance for the interference suppression is illustrated by computer simulation example.

• Journal of the Korea Fashion and Costume Design Association
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• v.20 no.3
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• pp.33-48
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• 2018

The purposes of this study were to investigate the social instrumentality of appearance, appearance orientation, and cosmetics purchasing behaviors of Chinese male consumers, and to find differences in the cosmetics purchasing behaviors of the male consumer groups, which were segmented by the social instrumentality of appearance and appearance orientation. The subjects were 400 adult males in their 20s to 30s from Gillim province in China. The measurements consisted of the social instrumentality of appearance, appearance orientation, cosmetics purchasing behavior, and the subject' demographic attributes. The data was analyzed by descriptive statistics, frequency analysis, $x^2$ test, multiple response analysis, cluster analysis, ANOVA, and Duncan's multiple range test, using SPSS program. The results were as follows. First, young Chinese male consumers had a high sense of the social instrumentality of appearance, but the tendency to invest time and effort to enhance their looks was still low. Second, on the basis of the social instrumentality of appearance and appearance orientation, young Chinese male consumers were classified into four groups (high involvement group, instrumentality group, orientation group, and low involvement group). Third, the four male consumer groups revealed many significant differences in various cosmetic purchasing behaviors (purchasing items, information sources, product selection criteria, purchasing motives, purchasing locations, store selection criteria, purchasing price, purchasing frequency, and cosmetics improvements). Therefore, the social instrumentality of appearance and appearance orientation are seen as significant variables to effectively segment the Chinese male consumer market. The cosmetics companies targeting young Chinese men need to establish differentiated marketing strategies, considering the characteristics of each segment of the consumer market.

• Journal of Ocean Engineering and Technology
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• v.24 no.6
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• pp.61-70
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• 2010

This study presents free vibration analyses of perforates steel plates with various cutouts. Four different parameters (shape, size, curvature radius ratio, and rotation of cutouts) were considered to investigate the effects of those parameters on the free vibration characteristics, such as natural frequencies of the perforated steel plates. Three different shapes of cutouts are circle, square, and triangle, and the considered sizes are 5, 10, 15, 20, and 25 mm. For the triangular and square cutouts, the characteristic radii of the inscribed circles of those cutouts were defined. In addition, the curvature radius ratio was defined as the ratio of curvature radius of bluntness and the characteristic radius. Then, total seven different curvature radius ratios (0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1) were considered. To investigate the rotation effect of the cutouts, it was considered four rotations ($0^{\circ}$, $15^{\circ}$, $30^{\circ}$, and $45^{\circ}$) for the square cutouts and three rotations (0, 15, and 30) for the triangular cutouts. All the free vibration analyses were conducted using a general purpose finite element program. From the analyses we found that the most influential parameter for the free vibration response of the perforated plates is the size of cutout. The other factors such as the shape, curvature radius ratio, and rotation are minors; they mainly change the natural frequency as long as the size effect is accompanied.

• Journal of Electrochemical Science and Technology
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• v.6 no.4
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• pp.131-138
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• 2015

Electrical discharge machining is an unconventional machining process in which successive sparks applied to machine the electrically conductive materials. Any changes in electrical discharge machining parameters lead to the pieces with distinct surface roughness. The electrical discharge machining process is well applied for high hardness materials or when it is difficult to use traditional techniques to do material removing. Furthermore, this method is widely applied in industries such as aerospace, automobile, molding, and tool making. CK45 is one of the important steels in industrial and electrical discharge machining can be considered as a proper way for its machining because of high hardness of CK45 after thermal operation of the electrical discharge machining process. Optimization of surface roughness as an output parameters as well as electrical discharge machining parameters including current, voltage and frequency for electrical discharge machining of CK45 has been studied using copper tools and kerosene as the dielectric. For such a purpose and to achieve the precise statistical analysis of the experiment results design of experiment was applied while non linear regression method was chosen to assess the response of surface roughness. Then, the results were analyzed by means of ANOVA method and machining parameters with more effects on the desired outputs were determined. Finally, mathematical model obtained for surface roughness.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.11
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• pp.45-55
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• 1999

The small signal analyzer for the stationary drift-diffusion equation is developed. The slotboom variables of the potential, electron and hole concentrations for the response of applied small signal are defined and the stationary drift-diffusion equation is linearlized on DC operation point by $S^3A$ method. Frontal solver, which is used to solve the global matrix, progresses the accuracy of the solution in high frequency and minimizes the requirement of the memory. The simulations are executed on the structure of 3 dimensional N'P junction diode and 2 dimensional n-MOSFET to verify the proposed algorithm. The average relative errors of the conductance and the capacitance compared with MEDICI are about 26% and 0.67 for N'P junction diode and 7.75% and 2.24% for n-MOSFET. The simulation by the proposed algorithm can analyze the stationary drift-diffusion equation for applied small signal in high frequency region about 100GHz.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.6
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• pp.27-33
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• 1984

This paper is an experimental gaudy on the digital hardware implementation of the R2-MF Receiver for 32 channel configurations used in signalling systems between ESS. There are many methods to detect MF signal by DSP techniques, but the requirement for MF detection needs not sharp frequency response, needs only decision about some specific frequencies exist or not at discrete frequency sampling points. The hardware used to implement this algorithm is Am 2900 series "bit-slice microprocessor" chips based on the microprogramming techniques for real time signal processing. And we used the additional Z-80A processor chips for the system control and the decision about which is the right MF signal from the detected MF spectrums. Hence we could enhance the flexibilities of the hardware and the software, this leads that this system is well suits for signalling systems used in TDM ESS.n TDM ESS.

• Toxicological Research
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• v.18 no.2
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• pp.129-138
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• 2002

The mouse lymphoma assay (MLA) has been recently validated as a sensitive and specific test system to determine the genotoxic potential for a chemical. The objective of this study is to evaluate the utility of MLA for detecting mutagens. Especially, to compare MLA with the in vitro chromosomal aberration test (CA), we performed MLA using the microwell method with three chemicals (hydroxyurea, theophylline and amino acid copper complex), which were reportedly positive in the CA. In cell treated with hydroxyurea, anti-neoplastic agent that blocks DNA replication, evidence of a positive response was obtained without S9 mix for 4 h and 24 h. In addition, analysis of colony size distribution at concentration that gave an elevated mutant fraction showed that hydroxyurea induced a high proportion of small type colonies, indicating that hydroxyurea-induced mutation is associated with large chromosomal deletion. Conversely, negative MLA result was obtained for theophylline, which was wed as central nervous system stimulator. Although theophylline increased the mutant frequency at concentration of 1250 $\mu\textrm{g}$/$\textrm{m}{\ell}$ with S9 mix for 4 h, a concentration-related increase in mutant frequency was not observed. The MLA result of amino acid copper complex was considered equivocal because the positive result was obtained at concentration showing 10% or less RS or RTG. Thus, among 3 CA-positive chemicals, positive MLA result was obtained for one. The other two chemicals were negative and equivocal. However MLA, which evaluates mutagenic potential of chemicals through colony formation by cell grouth, may provide a higher predictivity of carcinogenesis than CA.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.647-652
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• 2008

This paper focused on the application of finite element model updating technique to evaluate the structural properties of the reinforced concrete specimen using the data collected from shaking table tests. The specimen was subjected to six El Centro(NS, 1942) ground motion histories with different Peak Ground Acceleration(PGA) ranging from 0.06g to 0.50g. For model updating, flexural stiffness values of structural members(walls and slabs) were chosen as the updating parameters so that the converged results have direct physical interpretations. Initial values for finite element model were determined from the member dimensions and material properties. Frequency response functions(i.e. transfer functions), natural frequencies and mode shapes were obtained using the acceleration measurement at each floor and given ground acceleration history. The weighting factors were used to account for the relative confidence in different types of inputs for updating(i.e. transfer function and natural frequencies). The constraints based on upper/lower bound of parameters and sensitivity-based constraints were implemented to the updating procedure in this study using standard bounded variable least-squares(BVLS) method. The veracity of the updated finite element model was investigated by comparing the predicted and measured responses. The results indicated that the updated model replicates the dynamic behavior of the specimens reasonably well. At each stage of shaking, severity of damage that results from cracking of the reinforced concrete member was quantified from the updated parameters(i.e. flexural stiffness values).