• Journal of Korea Multimedia Society
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• v.20 no.4
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• pp.640-648
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• 2017

Sensors have limited resources in sensor networks, so efficient use of energy is important. In order to use the energy of the sensor node efficiently, researches applying mobile sink to the sensor network have been actively carried out. The sink node moves the sensor network, collects data from each sensor node, which spread the energy concentrated around the sink node, thereby extending the entire life cycle of the network. But, when the sink node moves, it requires a reset of the data transmission path, which causes a lot of control messages and delays. In this paper, we propose a CMS(Cluster-based Mobile Sink) method to support the movement of mobile sink in a cluster sensor environment. The proposed scheme minimizes an amount of control messages without resetting the routing paths of entire sensor networks by supporting the sink mobility path using the neighbor cluster list. And, it simplifies the routing path setup process by setting a single hop path between clusters without a gateway. The experiment results show that the proposed scheme has superior energy efficiency in processing and network structure, compared with existing clustering and mesh routing protocols.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.951-957
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• 2010

An optimal path generation method considering the safety of UGV(Unmanned Ground Vehicle) is proposed and demonstrated through examples. Among various functions of UGV, real-time obstacle avoidance is a key issue to realize realistic scenario in FCS(Future Combat Systems). A two-dimensional narrow corridor environment is considered as a test field. For each step of UGV movement, two objectives are considered: One is to minimize the distance to the target and the other to maximize the distance to the nearest point of an obstacle. A weighted objective function is used in the optimization problem. Equality and inequality constraints are taken to secure the UGV's dynamics and safety. The weighting factors are controlled by a fuzzy controller which is constructed by a fuzzy rule set and membership functions. Simulations are performed for two cases. First the weighting factors are considered as constant values to understand the characteristics of the corresponding solutions and then as variables that are adjusted by the fuzzy controller. The results are satisfactory for realistic situations considered. The proposed optimal path generation with the fuzzy control is expected to be well applicable to real environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.5
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• pp.709-714
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• 2018

Visual Reality technology is becoming more and more interesting as it attracts people's interest. VR technology is used in various markets such as games, animation, and education. However, there were many people experiencing motion sickness such as dizziness and headache due to the delay time between hardware such as a device for sending a video after experiencing a VR image and an HMD for reproducing an image. The system proposed in this paper focuses on the environment rather than the movement of the attraction and detects the dividing line existing on the path by the proximity sensor and accurately calculates the position on the path according to the user 's motion. Since the position of the user is synchronized with the VR image, the position error of the user is improved to 0.2%.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.131-138
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• 2008

Mobile Ad hoc NETworks (MANETs) refer to autonomous networks in which wireless data communications are established between multiple nodes in a given coverage area without a base station or centralized administration. Because of node mobility and limited battery life, the network topology may changes frequently. Selecting the most reliable path during route discovery process is important to improve performance in ad hoc networks. In this paper, an enhanced routing protocol based on AODV(Ad hoc On-demand Distance Vector routing) by monitoring variation of receiving signal strength is proposed. New metric function that consists of node mobility and hops of path is used for routing decision. For preventing route failure by node movement during data transmission, a new route maintenance named as LRC (Local Route Change) is presented. If the node movement is detected, the routing agent switches path to its neighbor node in LRC. Simulation results show that the performance of the proposed routing scheme is superior to previous AODY protocol.

• Journal of the Korea Society of Computer and Information
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• v.27 no.8
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• pp.135-142
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• 2022

In this paper, we propose a graph-based user route control for rapidly conducting virus inspections in emergency situations (eg, COVID-19) and a framework that can simulate this on a city map. A^* and navigation mesh data structures, which are widely used pathfinding algorithms in virtual environments, are effective when applied to CS(Computer science) problems that control Agents in virtual environments because they guide only a fixed static movement path. However, it is not enough to solve the problem by applying it to the real COVID-19 environment. In particular, there are many situations to consider, such as the actual road traffic situation, the size of the hospital, the number of patients moved, and the patient processing time, rather than using only a short distance to receive a fast virus inspection.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.216-219
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• 2012

In wireless ad-hoc networks, the nodes configuring a path act as routers with various mobility. If the path is broken by the movement of a node, a new path have to be found again. For this reason, the node with high mobility should be excluded from structuring a path as far as possible. In this paper, we propose an algorithm which excludes nodes with high mobility from constructing a path by collecting and managing the information of mobility. As the result, this can provide more stable paths. The proposed algorithm uses the extended AOMDV method. In this algorithm, we appends History Field and Decline Field in the routing table to collect and manage the mobility information. In addition, we add Mbl Field to RREP (Route Reply) message to apply the collected information to configure the real path.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.575-580
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• 2015

Asymmetric double gate(DG) MOSFET is a novel transistor to be able to reduce the short channel effects. This paper has analyzed a off current for conduction path of asymmetric DGMOSFET. The conduction path is a average distance from top gate the movement of carrier in channel happens, and a factor to change for oxide thickness of asymmetric DGMOSFET to be able to fabricate differently top and bottom gate oxide thickness, and influenced on off current for top gate voltage. As the conduction path is obtained and off current is calculated for top gate voltage, it is analyzed how conduction path influences on off current with parameters of oxide thickness and channel length. The analytical potential distribution of series form is derived from Poisson's equation to obtain off current. As a result, off current is greatly changed for conduction path, and we know threshold voltage and subthreshold swing are changed for this reasons.

• International Journal of Computer Science & Network Security
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• v.23 no.7
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• pp.1-8
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• 2023

An Orthogonal Frequency Division Multiplexing (OFDM) based wireless communication system has drawn wide attention for its high transmission rate and high spectrum efficiency in not only radio but also Underwater Acoustic (UWA) applications. Because of the narrow sub-carrier spacing of OFDM, orthogonality between sub-carriers is easily affected by Doppler effect caused by the movement of transmitter or receiver. Previously, Doppler compensation signal processing algorithm for Desired propagation path was proposed. However, other Doppler shifts caused by delayed Undesired signal arriving from different directions cannot be perfectly compensated. Then Receiver Bit Error Rate (BER) is degraded by Inter-Carrier-Interference (ICI) caused in the case of Multi-path Doppler channel. To mitigate the ICI effect, a modified Delay and Doppler Profiler (mDDP), which estimates not only attenuation, relative delay and Doppler shift but also sampling clock shift of each multi-path component, is proposed. Based on the outputs of mDDP, an ICI canceling multi-tap equalizer is also proposed. Computer simulated performances of one-tap equalizer with the conventional Time domain linear interpolated Channel Transfer Function (CTF) estimator, multi-tap equalizer based on mDDP are compared. According to the simulation results, BER improvement has been observed. Especially, in the condition of 16QAM modulation, transmitting vessel speed of 6m/s, two-path multipath channel with direct path and ocean surface reflection path; more than one order of magnitude BER reduction has been observed at CNR=30dB.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.194-198
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• 2005

Although the rainstorm causes local damage on large scale, it is difficult to predict the movement of the rainstorm exactly. In order to reduce the rainstorm damage of the rainstorm, it is necessary to analyze the path of the rainstorm using various statistical methods. In addition, efficient time interval of rainfall observation for the analysis of the rainstorm movement can be derived by applying various statistical methods to rainfall data. In this study, the rainstorm tracking using statistical method is performed for various types of rainfall data. For the tracking of the rainstorm, the methods of temporal distribution, inclined Plane equations, and cross correlation were applied for various types of data including electromagnetic rainfall gauge data and AWS data. The speed and direction of each method were compared with those of real rainfall movement. In addition, the effective time interval of rainfall observation for the analysis of the rainstorm movement was also investigated for the selected time intervals 10, 20, 30, 40, 50, and 60 minutes. As a result, the absolute relative errors of the method of inclined plane equations are smaller than those of other methods in case of electromagnetic rainfall gauges data. The absolute relative errors of the method of cross correlation are smaller than those of other methods in case of AWS data. The absolute relative errors of 30 minutes or less than 30 minutes are smaller than those of other time intervals.

• Journal of Korean Elementary Science Education
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• v.33 no.1
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• pp.181-194
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• 2014

The purpose of this study was to analyze the difference between eye movements according to science achievement of elementary school students on measuring tasks. Science achievement was graded by the results of Korea national achievement test conducted in 2012. As an assessment tool to check measuring task, two measuring measure problems from TSPS(Test of Science Process Skill; developed in 1994) which were suitable for eye tracking system were adopted. The subjects of this study were 3 underachievers and 3 overachievers from 6th grade who agreed to participate in the research. SMI was used to collect EMD (eye movement data). Experiment 3.2 and BeGaze 3.2 programs were used to plan experiment and analyze EMD. As a result, eye movements of participants in measuring task did not show the path to the common gaze by groups. To solve the problem of using specific measuring strategies related to the correct answer. Underachiever who failed in measuring tasks don't have enough measurement capabilities and lack eye movement through the area of interest for cognitive thinking. These results show that elementary school science curriculum dealing with measuring have to reflect a lot of step-by-step learning requires.