• Communications of the Korean Mathematical Society
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• v.22 no.4
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• pp.503-508
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• 2007

Using the notion of posets, a method to make BCK-algebras is considered. We show that if a poset has the least element, then the induced BCK-algebra is bounded.

• The Pure and Applied Mathematics
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• v.14 no.3
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• pp.223-230
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• 2007

We give an answer to the following question: Question. Let S be a subset of [0,1] containing a maximal element m > 0 and let C :=$\{I_{t}\;{\mid}\;t{\in}S\}$ be a decreasing chain of ideals of a BCK/BCI-algebra X. Then does there exists a fuzzy ideal ${\mu}(X)=S\;and\;C_{\mu}=C?$.

• Journal of Nutrition and Health
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• v.32 no.7
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• pp.781-786
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• 1999

This study was designed to investigate the effects of vitamin E supplementation on radical scavenger activity and immune responses in female judo athletes(n=18). The age and sex matched sedentary students were used as controls(n=15). The initial plasma vitamin E concentration, lipid peroxide level and radical scavenger activity (RSA) were not different between two groups. The supplementation of $\alpha$-tocopheryl acetate(400IU/d) for 4 weeks significantly increased plasma vitamin E concentration of the subjects in both groups. In addition, the decrease in thiobarbituric acid reactive substance(TBARS)(p<0.05) and enhancement of RSA(p<0.05) were observed in both groups. Percentages of total T-cells in the athletic group was lower than that in the control group(p<0.05). However, the ratio of CD4 / CD8(helper T-cal $l^pressor T-cell) was higher in the sports group, due to more decrease in CD8 subset than in CD4 subset. The concentrations of IgG and IgM in the sports group were significantly lower than those in the control group(p<0.05). Therefore, severe training of the athletic group seems to be associated with the changes of supplementation. In conclusion, vitamin E supplementation (400IU/d, 4 weeks) of the female university students improved antioxidative activities of the blood, by decreasing lipid peroxide and enhancing radical scavenger activity. Percentages of T lymphocytes and IgG and IgM concentrations in the athletic group were lower than those in the control group. Meanwhile, vitamin E supplementation had no effects on immune status in both groups.ps.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.11
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• pp.5304-5322
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• 2018

Since designing a feedback topology is a practical way to implement interference alignment at reduced cost of channel state information (CSI) feedback, six feedback topologies have been presented in prior works for a K-user multiple-input multiple-output interference channel. To fully reveal the potential benefits of the feedback topology in terms of the saving of CSI overhead, we propose a new feedback topology in this paper. By efficiently performing dimensionality-decreasing at the transmitter side and aligning interference signals at a subset of receivers, we show that the proposed feedback topology obtains substantial reduction of feedback cost over the existing six feedback designs under the same antenna configuration.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.1A
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• pp.8-16
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• 2012

Recent work has been shown that cognitive radio systems with multiple antenna at both transmitter and receiver are able to improve performance of secondary users. In such system, the main drawback is the increased complexity and raised cost as the number of antennas increase. It is desirable to apply antenna selection which select a subset of the available antennas so as to solve these problems. In this paper, we consider antenna selection method for cognitive radio systems in correlated channel from the IEEE 802.11n. For a multiple-input multiple-output(MIMO) system with more antennas at transmitter than the receiver, we select the same number of transmit antennas as that of receive antennas. The exhaustive search for optimal antenna becomes impractical. We present criterion for selecting subset in terms of projection of channel correlation vector to increase performance of secondary user with decreasing interference at primary user.

• Safety and Health at Work
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• v.6 no.1
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• pp.18-24
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• 2015

Background: In 2006, three farmers died at the bottom of an agricultural shallow well where the atmosphere contained only 6% oxygen. This study aimed to document the variability of levels of oxygen and selected hazardous gases in the atmosphere of wells, and to identify ambient conditions associated with the low-oxygen situation. Methods: A cross-sectional survey, conducted in June 2007 and July 2007, measured the levels of oxygen, carbon monoxide, hydrogen sulfide, and explosive gas (percentage of lower explosive limit) at different depths of the atmosphere inside 253 wells in Kamphaengphet and Phitsanulok provinces. Ambient conditions and well use by farmers were recorded. Carbon dioxide was measured in a subset of wells. Variables independently associated with low-oxygen condition (<19.5%) were identified using multivariate logistic regression. Results: One in five agricultural shallow wells had a low-oxygen status, with oxygen concentration decreasing with increasing depth within the well. The deepest-depth oxygen reading ranged from 0.0% to 20.9%. Low levels of other hazardous gases were detected in a small number of wells. The low-oxygen status was independently associated with the depth of the atmosphere column to the water surface [odds ratio (OR) = 13.5 for 8-11 m vs. <6 m], depth of water (OR = 0.17 for 3-<8 m vs. 0-1 m), well cover (OR = 3.95), time elapsed since the last rainfall (OR = 7.44 for >2 days vs. <1 day), and location of well in sandy soil (OR = 3.72). Among 11 wells tested, carbon dioxide was detected in high concentration (>25,000 ppm) in seven wells with a low oxygen level. Conclusion: Oxygen concentrations in the wells vary widely even within a small area and decrease with increasing depth.