• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.1
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• pp.211-232
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• 2024

In this paper, we consider the resource allocation and offloading decisions of device-to-device (D2D) cooperative UAV-assisted mobile edge computing (MEC) system, where the device with task request is served by unmanned aerial vehicle (UAV) equipped with MEC server and D2D device with idle resources. On the one hand, to ensure the fairness of time-delay sensitive devices, when UAV computing resources are relatively sufficient, an optimization model is established to minimize the maximum delay of device computing tasks. The original non-convex objective problem is decomposed into two subproblems, and the suboptimal solution of the optimization problem is obtained by alternate iteration of two subproblems. On the other hand, when the device only needs to complete the task within a tolerable delay, we consider the offloading priorities of task to minimize UAV computing resources. Then we build the model of joint offloading decision and power allocation optimization. Through theoretical analysis based on KKT conditions, we elicit the relationship between the amount of computing task data and the optimal resource allocation. The simulation results show that the D2D cooperation scheme proposed in this paper is effective in reducing the completion delay of computing tasks and saving UAV computing resources.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.221-225
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• 2005

This paper proposes a gain scheduled control technique using time-delay for the nonlinear system with plant uncertainties and unexpected disturbances. The time delay-based gain scheduled control depends on a direct estimation of a function representing the effect of uncertainties. The information from the estimation is used to cancel the unknown dynamics and the unexpected disturbances simultaneously. The proposed estimation scheme with a finite convergence time is formulated in order to estimate the unborn scheduling variable variation. In other words, the time delay-based gain scheduled control uses the past observation of the system's response and the control input to directly modify the control actions rather than to adjust the controller gains or to identify system parameters. It has a simple structure so as to minimize the computational burden. The benefits of this proposed scheme are demonstrated in the simulation of an electromagnetic suspension system with plant uncertainties and external disturbances, and the proposed controller is compared with the conventional state feedback controller.

• Journal of IKEEE
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• v.27 no.3
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• pp.234-238
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• 2023

In this paper, we propose a time-to-digital converter (TDC) with compensation capability for PVT (process, voltage, and temperature) variations. A typical delay line-based TDC measures time based on the inverter's propagation delay, making it fundamentally sensitive to PVT variations. This paper presents a method to minimize the resolution change of TDC by compensating for the propagation delay caused by the PVT variations. Additionally, it dopts Cyclic Vernier TDC (CVTDC) structure to provide a wide input detection range. The proposed CVTDC with PVT compensation function is designed using a 45nm CMOS process, consumes 8mW of power, offers a TDC resolution of 5 ps, and has an input detection range of about 5.1 ns.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.536-543
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• 2011

The heterogeneous postal delivery model assumes that each intermediate node in the multicasting tree incurs a constant switching time for each message that is sent. We have proposed a new model where we assume a more generalized switching time at intermediate nodes. In our model, a child node v of a parent u has a switching delay vector, where the ith element of the vector indicates the switching delay incurred by u for sending the message to v after sending the message to i-1 other children of u. Given a multicast tree and switching delay vectors at each non-root node 5 in the tree, we provide an O(n$^{\frac{5}{2}}$) optimal algorithm that will decide the order in which the internal (non-leaf) nodes have to send the multicast message to its children in order to minimize the maximum end-to-end delay due to multicasting. We also show an important lower bound result that optimal multicast switching delay problem is as hard as min-max matching problem on weighted bipartite graphs and hence O(n$^{\frac{5}{2}}$) running time is tight.

• Journal of KIISE
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• v.42 no.12
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• pp.1495-1502
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• 2015

Data compression involves a trade-off between delay time and data size. Greater delay times require smaller data sizes and vice versa. There have been many studies performed in the field of wireless sensor networks on increasing network life cycle durations by reducing data size to minimize energy consumption; however, reductions in data size result in increases of delay time due to the added processing time required for data compression. Meanwhile, as energy generation occurs periodically in solar energy-based wireless sensor networks, redundant energy is often generated in amounts sufficient to run a node. In this study, this excess energy is used to reduce the delay time between nodes in a sensor network consisting of solar energy-based nodes. The energy threshold value is determined by a formula based on the residual energy and charging speed. Nodes with residual energy below the threshold transfer data compressed to reduce energy consumption, and nodes with residual energy above the threshold transfer data without compression to reduce the delay time between nodes. Simulation based performance verifications show that the technique proposed in this study exhibits optimal performance in terms of both energy and delay time compared with traditional methods.

• The Korean Journal of Emergency Medical Services
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• v.16 no.1
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• pp.81-90
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• 2012

Objectives: This study is to research delay time comparison for later defibrillation after hands off according to the changes in defibrillation electrodes. Study purpose: In defibrillation treatment that is the only way for cardiac arrest by arrhythmia, it is to find defibrillator device which can minimize late defibrillation delay time after important affect of hands off. Study object and method: After hands off according to the defibrillator device, we collected total 40 people for emergency medicine doctor, internal medicine doctor, general surgeon, nurse, emergency medical technician who are working at 2 CN, CS University hospitals in Gwangju Jeollanamdo district to find out hand off shock interval(HOSI). We then researched their general properties like occupation sector, experiences in clinic, gender, completion of AHA ACLS-P training and more. Then 40 participants continued ventricular fibrillation cardiac arrest simulation training (using human-model mannequin) designed by researcher and performed their roles as defibrillation operator. Each of participant used manual paddle and performed 4 times of defibrillation (150J) during 8 minutes of CPR and in 8day, the defibrillator devices were replaced from manual paddle to self-adhesive electrodes pads and 4 times of defibrillation (150J) under same simulation condition as manual paddle were performed. Study result: In comparison for delay time of later defibrillation after hands off of manual paddle and self adhesive electrodes pad, the self adhesive electrodes pad ($7.0{\pm}0.5sec$) seemed to reduce delay time of later defibrillation significantly (p<0.05) compared to manual paddle ($10.0{\pm}0.9sec$). The self adhesive electrodes pad, according to the general properties of participants, had no particular change in delay time after later defibrillation for the statistics (p>0.05) but the manual paddle had statistically significant differences for the occupation sector, experiences in clinic and gender (p<0.05). Conclusion: In defibrillation, the self adhesive electrodes pad($7.0{\pm}0.5sec$) showed short HOSI compared to manual paddle ($10.0{\pm}0.9sec$) significantly (p<0.05) and it applied identically for both existence and non-existence of ACLS-P training completion, experiences in clinic, gender and occupation sector. The manual paddle had also significant difference in experiences in clinic and occupation sector (p<0.05). which means the effect on HOSI according to the job mastery. Therefore, if the clinic experience is short or in case for the occupations without frequent defibrillation treatment has a danger of lowering success rate for the defibrillation using manual paddle. Therefore, it is true that using self adhesive electrodes pad for defibrillation electrodes when performing manual defibrillation in pre-hospital as well as in-hospital steps can generally minimize delay time of later defibrillation after hands off.

• Journal of IKEEE
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• v.22 no.3
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• pp.862-865
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• 2018

The proposed scheme minimizes the Idle time under the residual energy of the sensor node to adjust the Sleep-Wakeup period and minimize unnecessary energy consumption. It is The proposed scheme minimizes the Idle time under the residual energy of the sensor node to adjust the Sleep-Wakeup period and minimize unnecessary energy consumption. It is an important process to control the Application Packet Framework including the PHY and the MAC layer at each node's Idle time with the Idle time mechanism state before the proposed function is executed. The Current Control Level of the Report Attribute is fixed at one sending / receiving node where power consumption can occur, by changing Sleep-Wakeup time, the low power consumption efficiency was improved while satisfying the transmission requirement of the given delay time constraint.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.10
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• pp.2509-2528
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• 2012

Time division multiple access (TDMA) is a widely used media access control (MAC) technique that can provide collision-free and reliable communications, save energy and bound the delay of packets. In TDMA, energy saving is usually achieved by switching the nodes' radio off when such nodes are not engaged. However, the frequent switching of the radio's state not only wastes energy, but also increases end-to-end delay. To achieve high energy efficiency and low delay, as well as to further minimize the number of time slots, a multi-objective TDMA scheduling problem for industrial wireless mesh networks is presented. A hybrid algorithm that combines genetic algorithm (GA) and simulated annealing (SA) algorithm is then proposed to solve the TDMA scheduling problem effectively. A number of critical techniques are also adopted to reduce energy consumption and to shorten end-to-end delay further. Simulation results with different kinds of networks demonstrate that the proposed algorithm outperforms traditional scheduling algorithms in terms of addressing the problems of energy consumption and end-to-end delay, thus satisfying the demands of industrial wireless mesh networks.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.699-703
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• 1993

When the error path can be modeled as a pure delay, an adaptive algorithm for slowly time varying system is proposed to minimize the sound pressure level. This algorithm makes it possible to use the fittered-x LMS algorithm with on-line delay modeling of the error path. Another simple adaptive algorithm for pure tone noise is proposed which eliminates the cross term in the multiple error filtered-x LMS algorithm.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.52-61
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• 2018

This research suggested the traffic signal timing calculation model for signal intersections based on sectional travel time. A detection system that collects sectional travel time data such as Urban Transport Information System(UTIS) is applied. This research developed the model to calculate saturation flow rate and demand volume from travel time information using a deterministic delay model. Moreover, this model could determine the traffic signal timings to minimize a delay based on Webster model using traffic demand volume. In micro simulation analysis using VISSIM and its API ComInterface, it checked the saturation conditions and determined the traffic signal timings to minimize the intersection delay. Recently, sectional vehicle detection systems are being installed in various projects, such as Urban Transportation Information System(UTIS) and Advanced Transportation Management System(ATMS) in Korea. This research has important contribution to apply the traffic information system to traffic signal operation sector.