• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제20권8호
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• pp.761-769
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• 2009

In this paper, we report on the channel capacity and diversity gain of the vehicle on-glass antenna for FM radio reception. The correlation coefficient and channel capacity were obtained using the simulated 3D radiation pattern of each antenna and the Rayleigh channel model for urban environment. To examine the channel capacity we used two antennas which are a simple straight antenna and L-type antenna. Then we observed the available channel capacity by varying the position of feeds and the shape of the L-type antenna. The sample antenna, which has a maximum feed distance with different polarizations, was built and the receiving performance was measured in the weak FM field area. From the results we confirmed that the distance between the feeds should be placed as far as possible for the high channel capacity. If the distance between the feeds are greater than a certain threshold value than the polarizations of the two antennas are getting more important for determining the channel capacity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권4호
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• pp.655-670
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• 2010

To be reversible as a data hiding method, the original content and hidden message should be completely recovered. One important objective of this approach is to achieve high embedding capacity and low distortion. Using predicted errors is very effective for increasing the embedding capacity. Sorting the predicted errors has a good influence on decreasing distortion. In this paper, we present an improved reversible data hiding scheme using upgraded histogram shifting based on sorting the predicted errors. This new scheme is characterized by the algorithm which is able to find the optimum threshold values and manage the location map effectively. Experimental results compared with other methods are presented to demonstrate the superiority of the proposed method.

• The Journal of Korean Physical Therapy
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• 제24권5호
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• pp.340-347
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• 2012

Purpose: This study was conducted in order to investigate the effect on respiratory function, trunk control, and functional activities of daily living (ADL) through respiratory muscle strength training in patients with chronic stroke. Methods: Eighteen subjects who were six months post stroke participated in this study. The subjects were randomly allocated to two groups: experimental (n=10) and control (n=8). Both groups received physical therapy for five sessions, 30 minutes per week, during a period of six weeks. Subjects in the experimental group participated in an additional respiratory muscle strength training program, in which the threshold PEP device was used for 30 minutes per day, three days per week, during a period of six weeks. Results from pretest-posttest control were evaluated by pulmonary function forced vital capacity (FVC), forced expiratory volume at one second (FEV1), FEV1/FVC, peak expiratory flow (PEF), capacity of cough, trunk control, and functional ADL. Results: Significant improvement in the FEV1, PEF of pulmonary function (p<0.05), cough function (p<0.05), and trunk control (p<0.05) was observed among the groups. Conclusion: Respiratory muscle strength training improves pulmonary function, capacity of cough, and trunk control. These results suggest that respiratory muscle strength training is feasible and suitable for individuals with chronic stroke.

• Journal of Communications and Networks
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• 제11권1호
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• pp.47-56
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• 2009

We investigate the connectivity of fading wireless ad-hoc networks with a pair of novel connectivity metrics. Our first metric looks at the problem of connectivity relying on the outage capacity of MIMO channels. Our second metric relies on a probabilistic treatment of the symbol error rates for such channels. We relate both capacity and symbol error rates to the characteristics of the underlying communication system such as antenna configuration, modulation, coding, and signal strength measured in terms of signal-to-interference-noise-ratio. For each metric of connectivity, we also provide a simplified treatment in the case of ergodic fading channels. In each case, we assume a pair of nodes are connected if their bi-directional measure of connectivity is better than a given threshold. Our analysis relies on the central limit theorem to approximate the distribution of the combined undesired signal affecting each link of an ad-hoc network as Gaussian. Supported by our simulation results, our analysis shows that (1) a measure of connectivity purely based on signal strength is not capable of accurately capturing the connectivity phenomenon, and (2) employing multiple antenna mobile nodes improves the connectivity of fading ad-hoc networks.

• Journal of Broadcast Engineering
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• 제15권5호
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• pp.681-696
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• 2010

In this paper, we examined the possibility of the transmission capacity increase by an extension and a modification of ATSC 8-VSB transmission system[1] for broadcasting a 3D HDTV services through 6 MHz terrestrial channel. First we examined the performance and the limit of conventional ATSC 8-VSB transmission system. After that LDPC & BCH code are employed instead of conventional RS & TCM code and the transmission parameter is founded for the capacity increase with resonable TOV by varying the code-rates and increasing the modulation constellation. We do not consider the perfect backward compatibility for maximum transmission capacity increase like DVB-S2 system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권9호
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• pp.4180-4196
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• 2017

In this paper, we analyze average capacity of an amplify-and-forward (AF) cooperative communication system model in multi-relay multiuser networks. In contrast to conventional cooperative networks, relays in the considered network have no embedded energy supply. They need to rely on the energy harvested from the signals broadcasted by the source for their cooperative information transmission. Based on this structure, a two-step selection scheme is proposed considering both channel state information (CSI) and battery status of relays. Assuming each relay has infinite or finite energy storage for accumulating the energy, we use the infinite or finite Markov chain to capture the evolution of relay batteries and certain simplified assumptions to reduce computational complexity of the Markov chain analysis. The approximate closed-form expressions for the average capacity of the proposed scheme are derived. All theoretical results are validated by numerical simulations. The impacts of the system parameters, such as relay or user number, energy harvesting threshold and battery size, on the capacity performance are extensively investigated. Results show that although the performance of our scheme is inferior to the optimal joint selection scheme, it is still a practical scheme because its complexity is much lower than that of the optimal scheme.

• Structural Engineering and Mechanics
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• 제39권1호
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• pp.147-168
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• 2011

To ensure safety and long term performance, structural control has rapidly matured over the past decade into a viable means of limiting structural responses to strong winds and earthquakes. Nonlinear response history analysis requires rigorous procedure to compute seismic demands. Therefore the simplified nonlinear analysis procedures are useful to determine performance of the structure. In this investigation, application of improved capacity demand diagram method in the control of structural system is presented for the first time. Developed pole assignment method (DPAM) in structural systems control is introduced. Genetic algorithm (GA) is employed as an optimization tool for minimizing a target function that defines values of coefficient matrices providing the placement of actuators and optimal control forces. The ground acceleration is modified under induced control forces. Due to this, performance of structure based on improved nonlinear demand diagram is selected to threshold of nonlinear behavior of structure. With small energy consumption characteristics, semi-active devices are especially attractive solutions for limiting earthquake effects. To illustrate the efficiency of DPAM, a 30-story steel moment frame structure employing the semi-active control devices is applied. In comparison to the widely used linear quadratic regulation (LQR), the DPAM controller was shown to be just as effective and better in the reduction of structural responses during large earthquakes.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제28권10C호
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• pp.936-941
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• 2003

Density evolution was developed as a method for computing the capacity of low-density parity-check(LDPC) codes under the sum-product algorithm [1]. Based on the assumption that the passed messages on the belief propagation model can be approximated well by Gaussian random variables, a modified and simplified version of density evolution technique was introduced in [2]. Recently, the min-sum algorithm was applied to the density evolution of LDPC codes as an alternative decoding algorithm in [3]. Next question is how the min-sum algorithm is combined with a Gaussian approximation. In this paper, the capacity of various rate LDPC codes is obtained using the min-sum algorithm combined with the Gaussian approximation, which gives a simplest way of LDPC code analysis. Unlike the sum-product algorithm, the symmetry condition [4] is not maintained in the min-sum algorithm. Therefore, the variance as well as the mean of Gaussian distribution are recursively computed in this analysis. It is also shown that the min-sum threshold under a gaussian approximation is well matched to the simulation results.

• Proceedings of the Korea Contents Association Conference
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• 한국콘텐츠학회 2006년도 추계 종합학술대회 논문집
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• pp.250-253
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• 2006

In this paper, we proposed a new method of the Adaptive steganography using complexity on bit planes of color image. Applying fixing threshold and variable length, if insert information into all bit plans, all bit plans showed different image quality. Therefore, we first defined the complexity on bit plane and data complexity, similarity insert information into bit plans. As a result, the proposed method increased the insertion capacity and improved the image quality than fixing threshold and variable length method.

• Journal of Nutrition and Health
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• 제28권9호
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• pp.904-913
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• 1995

The purpose of this study is to determine the effects of exercise programs on the treatment of chronic diseases. For this purpose, nine middle-aged women suffering from such chronic diseases as obesity, hypertension and coronary heart disease(CHD) were sampled to perform a 4-month-long exercise program which required the lactate threshold(LT) level corresponding to 70% of maximal oxygen uptake(VO2max). Thereupon, their physiques, physical fitness, blood components and physiological varibles were compared pre and post of exercise program. The results were summarized as follows ; 1) After the 4-month-long exercise program, %fat was significantly decreased, while such variables as grip strength, side step, trunk flexion and leg balance were significantly increased. 2) Blood components such as TG, TC, HDL-C, LDL-C, hemoglobin and hematocrit did not show and change in after exercise program. 3) Physiological varables such as HR, SBP, DBP, HR/LT, SBP/LT, DBP/LT, RPE/LT, VE/LT, VO2/LT and VO2 max showed significant increase after 4-month exercise program. These results suggest that regular aerobic exercise in a long period might help to decrease % fat and to increase aerobic capacity in middle-aged women suffering from chronic diseases.