• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.984-993
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• 2011

In this paper, we present a new method for efficient mobility management in infrastructure-based ad hoc networks. This type of network inherently takes the tree topology model in which an Internet gateway (IG) becomes a root. Accordingly, the nodes near the IG process get much more number of messages, thereby causing a bottleneck phenomenon that degrades network performance. This problem is known as a funneling effect. We present a method to maximize message aggregation in which the nodes in the networks form tree topology and perform skewed time synchronization according to the depths of the nodes during the tree construction process. We proved by resorting to simulation that the funneling effect is alleviated and network performance is improved greatly.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.41-42
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• 2007

DMAC is an energy efficiency and low latency protocol designed for data gathering tree structures. However, it causes the funneling effect which is many-to-one traffic patterns in tree structures, consequently, results in packet collisions, losses, and energy consumptions in low depth nodes. In this paper, we present an energy efficient MAC protocol with fairness-based scheduling to avoid the funneling effect of DMAC protocol. By using traffic information from children nodes, our protocol dynamically adjusts duty cycles of last-depth nodes to mitigate overloaded packets in the vicinity of the sink node. Therefore, we expect our protocol to save more energy and achieve better packet delivery ratio, compared to DMAC protocol.

• Wind and Structures
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• v.9 no.1
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• pp.23-35
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• 2006

The effect of buildings on flow in urban canopy is one of the most important problems in local/micro-scale meteorology. A large eddy simulation model is used to simulate the flow structure in an urban neighborhood and the bulk effect of the buildings on surrounding flows is analyzed. The results demonstrate that: (a) The inflow conditions affect the detailed flow characteristics much in the building group, including: the distortion or disappearance of the wake vortexes, the change of funneling effect area and the change of location, size of the static-wind area. (b) The bulk effect of the buildings leads to a loss of wind speed in the low layer where height is less than four times of the average building height, and this loss effect changes little when the inflow direction changes. (c) In the bulk effect to environmental fields, the change of inflow direction affects the vertical distribution of turbulence greatly. The peak value of the turbulence energy appears at the height of the average building height. The attribution of fluctuations of different components to turbulence changes greatly at different height levels, in the low levels the horizontal speed fluctuation attribute mostly, while the vertical speed fluctuation does in high levels.

• Physical Therapy Korea
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• v.31 no.2
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• pp.167-173
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• 2024

Background: Stress urinary incontinence (SUI) impacts the social, physical, and psychological well-being and quality of life of the patient. Several techniques exist for its management, including transcutaneous electrical stimulation (TES). Objects: We aimed to demonstrate the effects of TES on ultrasonographic variables and quality of life in women with SUI. Methods: This prospective study recruited 21 women who had been diagnosed with grade 1 or 2 SUI between July 2018 and March 2019. The exclusion criteria were pregnancy and a history of urogenital surgery. All participants were assessed at baseline and 8 weeks after intervention initiation. The bladder neck position (BNP), length of the urethra (LU), funneling index (FI), and rhabdosphincter thickness (RT) were measured. The Incontinence-Quality of Life (I-QOL) was used to assess incontinence-specific quality of life. Statistical significance level was set at p < 0.05. Results: Twenty-one patients with SUI used TES for 8 weeks. BNP and FI significantly decreased after intervention (p < 0.05). LU, anterior and posterior RT (indicators of external sphincter hypertrophy) significantly increased post-intervention (p < 0.05). The total I-QOL score increased from 64.81 to 71.86 after the intervention (p < 0.05). Conclusion: This intervention improved BNP, LU, FI, RT, and subjective indicators such as quality of life in women with SUI. Therefore, TES can be an effective non-surgical treatment method for improving SUI symptoms and quality of life in these patients.

• Journal of The Geomorphological Association of Korea
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• v.19 no.3
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• pp.1-22
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• 2012

The classification scheme of estuaries can be divided into two categories: qualitative classification based on geomorphic characteristics and quantitative classification based upon the physical properties of water body. While simple and intuitive scheme of the former is difficult to quantify, the latter is not easy to apply due to the lack of data. A classification scheme based on morphological convergence is very promising because it only requires easily accessible data such as width and depth of channels, as well as it can characterize estuaries in terms of tidal propagation. Thus, this paper examines the classification scheme based on estuarine morphological convergence using depth and width data obtained from 19 major Korean estuaries. Morphological convergence for each estuary was estimated with the estuarine length, width and depth data to get the convergence parameters, which includes the degree of funneling ${\nu}$ and the dimensionless estuarine length $y_0$. The transfer function ${\xi}({\nu},ky)$ is then deduced analytically from 1D depth-integrated hydrodynamic momentum equation and continuity equation for estuarine shapes. Tidal response of each estuary is finally calculated using ${\nu}$, $y_0$ and ${\xi}({\nu},ky)$ for comparison and classification. The 19 Korean estuaries were classified into three groups: tidal amplitude-dominated estuaries with standing wave-like tidal response (group 1), current-dominated estuaries with progressive wave-like tidal response (group 2), and the intermediate group (group 3) between groups 1 and 2. The sensitivity analysis revealed that uncertainties in determining the estuarine length can have a critical effect upon the results of classification, which indicates that the reasonable determination of the estuarine length is of critical importance. Once the estuarine length is feasibly determined, depth-convergence can be neglected without any negative effect on the classification scheme, which has an important ramification on the wide applicability of the classification scheme.