• Journal of Communications and Networks
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• v.10 no.2
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• pp.213-220
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• 2008

This paper analyzes a broadcasting technique for wireless multi-hop sensor networks that uses a form of cooperative diversity called opportunistic large arrays (OLAs). We propose a method for autonomous scheduling of the nodes, which limits the nodes that relay and saves as much as 32% of the transmit energy compared to other broadcast approaches, without requiring global positioning system (GPS), individual node addressing, or inter-node interaction. This energy-saving is a result of cross-layer interaction, in the sense that the medium access control (MAC) and routing functions are partially executed in the physical (PHY) layer. Our proposed method is called OLA with a transmission threshold (OLA-T), where a node compares its received power to a threshold to decide if it should forward. We also investigate OLA with variable threshold (OLA-VT), which optimizes the thresholds as a function of level. OLA-T and OLA-VT are compared with OLA broadcasting without a transmission threshold, each in their minimum energy configuration, using an analytical method under the orthogonal and continuum assumptions. The trade-off between the number of OLA levels (or hops) required to achieve successful network broadcast and transmission energy saved is investigated. The results based on the analytical assumptions are confirmed with Monte Carlo simulations.

• Journal of the Korean Society for Precision Engineering
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• v.9 no.4
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• pp.22-35
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• 1992

In highly automated machining centers, intelligent sensor fddeback systems are indispensable on order to monitor their operations, to ensure efficient metal removal, and to initate remedial action in the event of accident. In this study, an on-line tool wear detection system for thrning operations is developed, and experimentally evaluated. The system employs multiple sensors and the signals from these sensors are processed using a multichannel autoegressive (AR) series model. The resulting output from the signal processing block is then fed to a previously tranied artificial neural network (multiayered perceptron) to make a final decision on the state of the cutting tool. To learn the necessary input/output mapping for tool wear detection, the weithts and thresholds of the network are adjusted according to the back propagation (BP) method during off-line training. The results of experimental evaluation show that the system works well over a wide range of cutting conditions, and the ability of the system to detect tool wear is improved due to the generalization, fault-tolearant and self-ofganizing properties of the neural network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.271-281
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• 2005

This paper for establishing the reliability of the TPC command is introduced, where the soft symbol of the TPC command itself is directed used as a reliability indicator. In addition to the new reliability estimation, the concept of parallel use of TPC algorithms is presented. The results show that the soft symbol reliability estimation decrease the $P_{tx}$ levels with 0.3 dB, thus providing a useful capacity gain. The parallel use of 2 to 4 algorithms is also shown to decrease the sensitivity of the algorithms to the algorithm thresholds used, and thus increase the feasibility of the algorithms in a real world networks.

• Journal of Oral Medicine and Pain
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• v.22 no.1
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• pp.183-192
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• 1997

Pressure pain thresholds are routinely used in orofacial pain research to evaluate the response of deep orofacial tissues to mechanical stimulation. Like other psychophysical measurements, however, this technique must stimulate cutaneous tissues before stimulating deeper tissues. This study aimed at evaluating the influence of the cutaneous hypoesthesia on the pressure pain threshold in 30 healthy volunteers. PPTs were determined with electric pressure algometry over masseter, temporalis anterior, sternocleidomastoid, and trapezius muscle before and after skin hypoesthesia. A local anesthetic cream and a control cream were applied following a placebo-controlled double-blind design and PPTs were reassessed. Two examiners measured PPTs two times on each muscles, randomly. And the EMG activity of all muscles were measured to evaluate the relationship with PPTs. The collected data were processed by SAS/STAT program. The obtained results were as follows : 1. There were a tendency to increase PPTs after than before cutaneous hypoesthesia, but, there were no significant difference statistically. 2. PPTs were consistently higher in anterior temporalis than in masseter muscle. 3. In all occasions, PPTs were higher in males than in females(p<0.001). 4. A statistically significant correlation was obtained from values of intra-examiners and inter-examiners in all measured muscles. 5. A significantly positive correlation was not found between PPT and functional EMG activity.

• Smart Structures and Systems
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• v.2 no.4
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• pp.339-355
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• 2006

A procedure to retrofit existing essential facilities subjected to seismic excitation is proposed. The main features of this procedure are to reduce maximum acceleration and associated forces in buildings subjected to seismic excitation by reducing their strength (weakening). The weakening retrofit, which is an opposite strategy to strengthening, is particularly suitable for buildings having overstressed components and foundation supports or having weak brittle components. However, by weakening the structure large deformations are expected. Supplementaldamping devices however can control the deformations within desirable limits. The structure retrofitted with this strategy will have, therefore, a reduction in the acceleration response and a reduction in the deformations, depending on the amount of additional damping introduced in the structure. An illustration of the above strategy is presented here through an evaluation of the inelastic response of the structure through a nonlinear dynamic analysis. The results are compared with different retrofit techniques. A parametric analysis has also been carried out to evaluate the effectiveness of the retrofitting method using different combination of the performance thresholds in accelerations and displacements through fragility analysis.

• Journal of Climate Change Research
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• v.7 no.2
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• pp.205-215
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• 2016

The relationship between the climate and the number of heat-related patients in South Korea was analysed in this study. The number of the patients was 1,612 during the summer 2011 to 2015 according to the Heat-related Illness (HRI) surveillance system. The coefficient of determination between the number of the patients and the daily maximum temperature was higher than that between the number of them and the other elements: the daily mean/minimum temperature and relative humidity. The thresholds of daily maximum and minimum temperature in metropolitan cities (MC) were higher than those in regions except for MC (RMC). The higher the maximum and minimum temperature became, the more frequently the heat-related illness rate was observed. The regional difference of this rate was that the rate in RMC was higher than that in MC. Prolonged heat wave and tropical night tended to cause more patients, which continued for 20 days and 31 days of maximum values, respectively. On the other hand, the relative humidity was not proportional to the number of the patients which was rather decreasing at over 70% of relative humidity.

• Journal of Environmental Science International
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• v.30 no.1
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• pp.45-55
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• 2021

In this study, the odor of the parts and the odor of the surrounding environment were classified and verified. In order to increase the reliability of odor quantitative/qualitative analysis, the selection criteria for 5 sensory evaluators were established, and the n-Butanol control solution for each odor intensity was periodically trained to recognize the odor intensity before sensory evaluation. In addition, although various odor thresholds have been used through several studies, verification of whether the odor intensity value obtained through GC/MSD analysis is similar to the degree to which a person directly smells and feels it. It is important to select the odor threshold that has the best correlation with the odor intensity calculated by the person smelling the odor. Finally, sampling and measuring flowing airflow and temporary odors such as odor component analysis was experimentally difficult due to limited collection space and differences in concentration of generated components. In this study, a quantitative analysis was made possible by using the low temperature concentration (cooling) trap method. Through this, it was confirmed that the correlation with the actual odor intensity was not caused by the product itself, but by the environmental factor discharged from the product after creating the odor environment.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1367-1369
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• 2013

Applying Application-Level Multicast technology (ALM) to Distributed Interactive Applications (DIAs) becomes more and more popular. Especially for DIAs embedded priority that the sender forwards data to receivers due to their respective priorities. The priority-based directed minimum spanning tree (PST) algorithm was designed for these DIAs. However, the PST has no efficient priority selection and filtering mechanism. The system will consume a tremendous amount of resource for reconstructing distribution tree and becomes unstable and unscalable. In this paper, First, We propose a novel priority-based application level multicast algorithm: Predict-and-Quantize for Priority with directed minimum Spanning Tree (PQPST), which can efficiently predict efficient priorities for the receivers and quantize the predicted priorities to build the multicast distribution tree. Second, we propose Priority Discrepancy Heuristic Mechanism (PDHM), which sets different thresholds of priority discrepancy within the priority discrepancy interval to control the distribution tree construction can efficiently decrease the repeated distribution tree construction, and we get the best heuristic priority discrepancy interval by PQPST. According to the simulation results, the PQPST and PDHM can efficiently improve the performance of the PST algorithm.

• Physical Therapy Rehabilitation Science
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• v.11 no.3
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• pp.329-334
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• 2022

Objective: Low back pain (LBP) is a symptom that accounts for a large proportion of musculoskeletal pain. Among them, non-specific LBP (NSLBP) means that the pathological cause is unknown, and belongs to the most common LBP. Studies on the mechanism of muscle control in LBP are insufficient, and quantitative studies are needed. Design: Observational cross-sectional study design Methods: A Thirty participants with NSLBP symptoms were enrolled, and their pressure pain thresholds (PPT) and muscle and fat thickness were measured. Participants measured the paraspinal muscles (PM) of the thoracic and lumbar spine and medial hamstring (semitendinosus) on the dominant and non-dominant sides in the prone position. Results: Among the variables that were significant in the correlation analysis, PM of the thoracic and lumbar spine showed a significant relationship in the PPT ([thoracic spine PM]=1.141+0.912 [lumbar spine PM]). Also, there was a significant relationship between the lumbar spine PM in the PPT and the thoracic spine PM in the muscle thickness ([lumbar spine PM of PPT]=4.057+0.117 [thoracic spine PM of muscle thickness]) Conclusions: Although there was no muscle imbalance according to the dominant and non-dominant side, there is a correlation between the pressure pain threshold and the muscle thickness between the paraspinal muscles of the thoracic spine and the lumbar spine.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.646-648
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• 2021

Sensors with wireless communication functions are essential for acquiring and transmitting spatio-temporal data that is not easily accessible in sensor network environments. However, these sensors lack adaptability to large amounts of sensing data processing or dynamic environments, resulting in over-consumption of power and network overhead. This paper proposes a mobile agent that can acquire, transmit, and process only the necessary data by applying thresholds, and presents methods for autonomous migration and communication processing of mobile agents.