• The Journal of the Society of Korean Medicine Diagnostics
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• v.11 no.1
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• pp.157-166
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• 2007

Background: The change in the respiratory pattern has an influence on the change in the autonomic nervous system, which in turn has an influence on the EGG to measure a gastric activity. However, the study on the influence on the EGG parameters by respiratory control and on the correlation between the HRV and EGG through respiratory control has not been perform yet. Objective: It is to perform a series of experiments to find out how the EGG parameters are influenced by the controlled respiration and what correlation there may exist between the EGG and HRV to measure the change in the autonomic nervous system after controlled respiration. Methods: 1st Experiment: During a 15minutes' voluntary respiration, HRV was measured, and it was measured again during another 15 minutes' controlled respiration. 2nd Experiment: After an eight hours' fast, EGG was measured for a period of 30 minutes, and then after another 15 minutes' voluntary respiration, a test-meal was offered for 10 minutes and again EGG was measured. The next day, after an 8 hour's fast, EGG was measured for 30 minutes, and after a 15 minutes' controlled respiration and offered with a test-meal for 10 minutes and then EGG was measured again for 30 minutes. Results: 1. It was observed in all the channels that the power ratio increased more after controlled respiration than after voluntary respiration. No statistical significance, however, could be observed. 2. Through controlled respiration, the HF of HRV and the power ratio of EGG Channel 4 was negatively correlated, while the LF/HF of HRV and the power ratio of EGG channel 1 & 4 was positive correlated. Such correlations as mentioned above, however, could not be observed in HRV & EGG through voluntary respiration. Conclusions: 1. It was concluded that the increase in the power of gastric contractile after controlled respiration is bigger than the increase in the power of gastric contractile after voluntary respiration. 2. It was concluded that the gastric contractile power and sympathetic activity through controlled respiration was negatively correlated, while the gastric contractile power and parasympathetic activity through controlled respiration was positively correlated.

• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.95-103
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• 2009

In this paper, a generation method of transmit and receive beamforming vectors based on base station cooperation is proposed which maximizes the user SINR in mobile cellular multi-user MIMO systems. There are two main sources of interference which deteriorate the performance of the system, i.e. the inter-user interference caused by the usage of the same radio resource for multiple users in the system, and the inter-cluster interference from neighboring base stations which are not participating in cooperative transmission. The proposed scheme cancels out the inter-user interference by using the block diagonalization(BD) method, and mitigate the inter-cluster interference by using optimal transmit and receive beamforming vectors based on optimal combining(OC) with the statistic information of inter-cluster interference. We perform computer simulations to verify the performance of the proposed scheme, and compare the result to the conventional performance obtained from utilizing the receiver side information only or utilizing the information from neither sides. The performance evaluations are conducted not only over the independent MIMO channels, but over correlated MIMO channels to demonstrate the robustness of the proposed scheme over the channels with correlation among antennas.

• Journal of Applied Biological Chemistry
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• v.44 no.3
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• pp.105-112
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• 2001

Insect pests can be controlled through direct application of insecticides. Insect control by residual protectants is relatively inexpensive and has an advantage of destroying all stages of infestations. The efficacy of control is largely determined by the concentration of insecticides to which the pest species is exposed. A reduction in the period of control in the field afforded by a specific level of a protectant indicates that resistance has developed. An increase in the level of protectant is required to maintain control, and the efficacy of currently used insecticides has been severely reduced by insecticide resistance in pest species. Development of resistance to particular insecticide varies with species because insecticide resistance is often correlated with increased levels of certain enzymes, which are cytochrome P450-dependent monooxygenases, glutathione S-transferases and esterases. Some sections of insecticide molecules can be modified by one or more of these primary enzymes. A reduction in the sensitivity of the action site of a xenobiotic also constitutes a mechanism of resistance. Acetylcholinesterase is a major target site for insecticide action, as are axonal sodium ion channels and ${\gamma}$-aminobutyric acid receptors. Development of reduced sensitivity of these target sites to insecticides usually occurs. This review not only may contribute to a better understanding of insecticide resistance, but also illustrates the gaps still present for a full biochemical understanding of the resistance.

• Journal of Biomedical Engineering Research
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• v.28 no.6
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• pp.777-785
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• 2007

In this paper, Finger-Toe Index (FTI) is proposed as an analytic parameter for the characterization of arterial vessel. Different from the currently being employed pulse wave velocity (PWV) information of the volume pulse wave measured from 4 arterial channels, the proposed FTI uses the ratio of the shorter of the two up-stroke time of PPG from fingers ($UT_{finger}$) and that of PPG (Photoplethysmography) from toes ($UT_{toe}$). To verify the usefulness of the proposed method, Finger-Toe Indexes were derived from the volume pulse waves acquired from 50 people under examination aged from 12 to 81 years old, and they were then compared with blood pressure ankle-brachial index (ABI). It was successfully demonstrated that the arterial stiffness can be estimated with respect to age and FTI is more strongly correlated with the pulse transit time than ABI. From the regression analysis, we also found that FTI has significant correlation PWV for a quantitative index of arterial stiffness and provides more accurate information than ABI for the characterization of arterial vessel.

• Journal of Communications and Networks
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• v.5 no.2
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• pp.104-115
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• 2003

It is well known that Multiple Input Multiple Output (MIMO) systems offer the promise of achieving very high spectrum efficiencies (many tens of bit/s/Hz) in a mobile environment. The gains in MIMO capacity are sensitive to the presence of spatial and temporal correlation introduced by the radio environment. In this paper, we examine how MIMO capacity is influenced by a number of factors e.g., a) temporal correlation b) various combinations of low/high spatial correlations at either end, c) combined spatial and temporal correlations. In all cases, we compare the channel capacity that would be achievable under independent fading. We investigate the behaviour of "capacity fades," examine how often the capacity experiences the fades, develop a method to determine level crossing rates and average fade durations and relate these to antenna numbers. We also evaluate the influence of channel correlation on the capacity autocorrelation and assess the fit of a Gaussian random process to the temporal capacity sequence. Finally we note that the particular spatial correlation structure of the MIMO channel is influenced by a large number of factors. For simplicity, it is desirable to use a single overall correlation measure which parameterizes the effect of correlation on capacity. We verify this single parameter concept by simulating a large number of different spatially correlated channels.

• Journal of Communications and Networks
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• v.12 no.4
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• pp.334-345
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• 2010

In this paper, we study optimal tradeoffs of achievable throughput versus consumed power in wireless ad-hoc networks formed by a collection of multiple antenna nodes. Relying on adaptive modulation and/or dynamic channel coding rate allocation techniques for multiple antenna systems, we examine the maximization of throughput under power constraints as well as the minimization of transmission power under throughput constraints. In our examination, we also consider the impacts of enforcing quality of service requirements expressed in the form of channel coding block loss constraints. In order to properly model temporally correlated loss observed in fading wireless channels, we propose the use of finite-state Markov chains. Details of fading statistics of signal-to-interference-noise ratio, an important indicator of transmission quality, are presented. Further, we objectively inspect complexity versus accuracy tradeoff of solving our proposed optimization problems at a global as oppose to a local topology level. Our numerical simulations profile and compare the performance of a variety of scenarios for a number of sample network topologies.

• Fisheries and Aquatic Sciences
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• v.1 no.1
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• pp.113-121
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• 1998

A relationship between sea level variations in the Korea Strait (the western and the eastern channels) and the Tokara Strait in the Kuroshio region is examined using daily-mean sea level data from 1966 to 1986. The seasonal variation of the sea level difference (SLD) between Izuhara and Pusan (the western channel) is most periodic: the positive anomalies appear from summer to autumn, and the negative anomalies from winter to spring year to year, whereas SLDs neither between Hakata and Izuhara (the eastern channel) nor between Naze and Nishinoomote (the Tokara Strait) show such a periodic variation. Much similarity has been found between SLDs in the eastern channel and the Tokara Strait, and in particular they were closely correlated in a special event of the Kuroshio region, such as a large meander of the Kuroshio. This paper shows that the periodic seasonal variation of the SLDs in the western channel should be less related to the Kuroshio region. This result also implies that the variation of SLD in the western channel is largely influenced by local factors, such as the bottom cold water in the western channel in summer, rather than from the Kuroshio region.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.4
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• pp.310-319
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• 1996

The existing coders used in the fading channels are designed under the assumption that the ideal interleaver, which removes the fading correlation of the channel, is used. With the non-ideal interleaver of finite size, however, the performance of the coded modulation system degrades rapidly when the fading is very slow. A new method which achieves interleaving effects by switching the transmitter antennas is suggested to improve the performance even in the slow fading. The performance of the new system is analyzed. The results show significant performance improvement in the slow fading and at least no deterioration in the fast fading over the existing systems.

• Journal of Communications and Networks
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• v.7 no.4
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• pp.450-461
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• 2005

In this paper, we derive analytical expressions for the exact pairwise error probability (PEP) of a space-time coded system operating over spatially correlated fast (constant over the duration of a symbol) and slow (constant over the length of a code word) fad­ing channels using a moment-generating function-based approach. We discuss two analytical techniques that can be used to evaluate the exact-PEPs (and therefore, approximate the average bit error probability (BEP)) in closed form. These analytical expressions are more realistic than previously published PEP expressions as they fully account for antenna spacing, antenna geometries (uniform linear array, uniform grid array, uniform circular array, etc.) and scattering models (uniform, Gaussian, Laplacian, Von-mises, etc.). Inclusion of spatial information in these expressions provides valuable insights into the physical factors determining the performance of a space-time code. Using these new PEP expressions, we investigate the effect of antenna spacing, antenna geometries and azimuth power distribution parameters (angle of arrival/departure and angular spread) on the performance of a four-state QPSK space-time trellis code proposed by Tarokh et al. for two transmit antennas.