• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.125-130
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• 1997

Effect of cross-section libraries on displacements per atom (dpa) was investigated under the spectrum which is calculated in the outer and inner of capsule in the JMTR fuel region. The variation of dpa value of iron was calculated by TENJIN2 code using several cross section libraries (ENDFB-lV, JENDL 3.1 and JENDL 3.2). The dependency of input spectrum on total damage (dpa) is more clearly appeared in case or ENDFB-IV in JENDL 3.2 and JENDL 3.1 libraries. The gas production rate calculated by ENDFB-IV library showed slightly larger value than that by JENDL library, and it responded more sensitively in neutron spectrum.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.10
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• pp.994-1001
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• 2009

CSS (Chirp Spread Spectrum) specified in IEEE 802.15.4a can be used for ranging applications. In this paper, we apply the CSS to estimate the coordinates of a mobile robot. Four anchor nodes are installed at known positions and a tag node is attached to the target mobile robot. By CSS ranging, we measure the distances between each anchor and the tag node. Based on the measured distances, the coordinates of the mobile robot can be calculated by the method of trilateration. However the calculated coordinates are not accurate because of the errors of the measured distances. Therefore we propose an algorithm for reducing the effect of the errors. The proposed algorithm is executed with the extended Kalman filter. Through localization experiments, we show the performance of the proposed algorithm and the accuracy of the estimated position.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.984-991
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• 2007

Cognitive Radio is an advanced enabling techlology for efficient utilization of under-utilized spectrum since it is able to sense the temporally available spectrum and adapt its parameters to fully utilize the frequency band. Recent investigation suggests that spectrum sensing is compromised when a cognitive radio user suffers from the environment with fading or shadowing. In order to combat the effect, collaborative sensing is considered to be a promising way, which combines the sensing result of each user to achieve good performance. However, the conventional collaborative sensing is not efficient when users suffer different fading environments. In this paper, we propose a weighted-collaborative scheme that considers using the weights of each collaborative CR user, which can achieve better sensing performance under both fast and slow fading environments. The analysis of the simulation resultsproves that the weighted-collaborative scheme improves sensing performance obviously and outperforms the conventional method.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.147-155
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• 1996

This study investigated the characteristics of ultrasonic-energy-added diesel fuel. We compared the characteristics used H-NMR spectrum, FT-IR spectrum, viscosity and surface tension between conventional diesel fuel and ultrasonic-energy-added diesel fuel. The result are obtained as follow : We knew that ultrasonic energy result to reduce BI and weaken viscosity and surface tension. Also, the ultrasonic energy caused to reduce aromatics Ha and increase Alkanes Hγ. The effect of ultrasonic-energy-added dieselfuel was principally caused by change of chemical structures and a physical characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.815-820
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• 1998

A new coding algorithm which has spectrum notches at the DC and Nyquist Frequency for maximizing the effect of the in-band pilot insertion in order to make the symbol timing or carrier recovery easy is proposed. It is shown that this algorithm uses one encoder and gives the similar spectrum characteristics to that of the existing OF00 code which uses two encoder. In this paper, the proposed new coding algorithm is explained andits spectrum characteristics is compared with the of OF00 code using computer simulation.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1644-1654
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• 2018

Eigenvalue distributions for a periodic metal-insulator-metal waveguide, classified into the point spectrum and the discretized continuous spectrum (DCS), are investigated as functions of frequencies, gap widths, and periods. Muller's method is suggested for solving exact eigenvalues, and we propose the scheme for finding proper initial values in the Muller's method by considering only ${\Re}e({\varepsilon}_r)$ in the dispersion equation. We then find that anti-crossing behavior, repulsive effect between the point spectrum and the DCS, becomes stronger when the real parts of the roots in the point spectrum have smaller values. Finally, we examine the transmittances of a single subwavelength slit for real metals using the mode matching technique. The transmittances in real metals similarly follow those of the perfect electric conductor (PEC) at low frequencies, while the patterns at higher frequencies begin to differ from the PEC.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.600-603
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• 2003

Energy spectrum modulation of X-ray source in digital mammography has been studied. In this study, we calculated various filtered spectra using the scattering data. Primary spectra were generated by Molybdenum (Mo) and Tungsten (W) targets. The materials of added filters are Molybdenum and Rhodium (Rh) for 40 kVp Mo. primary spectrum, the amounts of photons over whole energy ranges are attenuated to 0.43 with 0.03 mm Mo filter and 0.38 with 0.06 mm Mo filter while the photons of energy ranged from 17 keV to 20 keV. The photons of low energy ranged below 17 keV are considerably attenuated. This effect brings out reducing the scattered radiation and dose to the patient, and enhancing subject contrast in the image. The results show that filtered spectra are not seriously affected by X-ray tube loadability. Because the energy range from 17 keV to 20 keV is directly transmitted although low and high energies are mainly filtered.

• Clinical and Experimental Pediatrics
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• v.64 no.6
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• pp.286-292
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• 2021

Background: The effect of exposure to environmental factors on autism spectrum disorders (ASD), especially during pregnancy, is unclear. Purpose: This meta-analysis investigated the association between exposure to pesticides and polychlorinated biphenyls (PCBs) during pregnancy and ASD risk among children. Methods: We searched Scopus, PubMed, Web of Science, and ProQuest for articles published through September 2019. Random-effects models were used to examine the association among studies using pooled odds ratios (ORs) and their 95% confidence intervals (CI). I2 tests were used to measure interstudy heterogeneity. Results: The pooled OR indicated a significant association between PCB and pesticide exposure during pregnancy and ASD risk among children (OR, 1.80; 95% CI, 1.26-2.34; and OR, 1.20; 95% CI, 1.02-1.39), respectively. Conclusion: Findings of the present study indicate that exposure to pesticides and PCBs during pregnancy may affect the risk of ASD among children.

• Journal of the Earthquake Engineering Society of Korea
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• v.1 no.1
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• pp.25-29
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• 1997

Amplication factor spectrum, using the observed strong ground motions database, has been obtained and compared with Standard Response Spectrum. The observed ground motions from the Miramichi, Nohanni, Sagueray and New Madrid Earthquake (19 vertical components, 36 horizontal components), which are estimated to represent domestic seismotectonic characteristics such as seismic sources, attenuation, and site effect, are used for the analysis of amplification factor spectrum. Amplication factors have been calculated by comparing the observed peak ground motions with results form responses to the observed horizontal and vertical ground motions. The comparison shows that the amplification factors resultant from this study exceed those of Standard Response Spectrum of relatively higher frequencies. The result implles that the characteristics of the seismic strong ground motion, which may represent the domestic seismotectonic characteristics differ from of standard Response Spectrum, especillay of higher frequencies.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.2
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• pp.169-187
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• 2008

Performance-based approaches as an alternative method of the existing force-based approach have gradually become recognized tools for the seismic design and evaluation. The maximum inelastic displacement response using capacity spectrum method (CSM) with elastic response spectrum is estimated from seismic response of equivalent linear system converted from nonlinear system. The purpose of this paper is to evaluate accuracy of capacity spectrum method using the equivalent SDOF methods of 4 types and the equivalent damping methods of 5 types for RC wall structure. In order to evaluate accuracy of capacity spectrum analysis, the shaking table test results for RC wall structures are compared with those by the capacity spectrum analysis. Also, the effect of bilinear capacity curves by two bilinear approximation methods for capacity spectrum analysis is compared.