• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.6
• /
• pp.2492-2512
• /
• 2018

Multicast communication can effectively reduce network resources consumption in contrast with unicast. With the advent of SDN, current researches on multicast traffic are mainly conducted in the SDN scenario, thus to mitigate the problems of IP multicast such as the unavoidable difficulty in traffic engineering and high security risk. However, migration to SDN cannot be achieved in one step, hybrid SDN emerges as a transitional networking form for ISP network. In hybrid SDN, for acquiring similar TE and security performance as in SDN multicast, we redirect every multicast traffic to an appropriate SDN node before reaching the destinations of the multicast group, thus to build up a core-based multicast tree substantially which is first introduced in CBT. Based on the core SDN node, it is possible to realize dynamic control over the routing paths to benefit traffic engineering (TE), while multicast traffic manageability can also be obtained, e.g., access control and middlebox-supported network services. On top of that, multiple core-based multicast trees are constructed for each multicast group by fully taking advantage of the routing flexibility of SDN nodes, in order to further enhance the TE performance. The multicast routing and splitting (MRS) algorithm is proposed whereby we jointly and efficiently determine an appropriate core SDN node for each group, as well as optimizing the traffic splitting fractions for the corresponding multiple core-based trees to minimize the maximum link utilization. We conduct simulations with different SDN deployment rate in real network topologies. The results indicate that, when 40% of the SDN switches are deployed in HSDN as well as calculating 2 trees for each group, HSDN multicast adopting MRS algorithm can obtain a comparable TE performance to SDN multicast.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.1
• /
• pp.8-14
• /
• 2020

The human impact of particulate matter are revealed and demand for improved forecast accuracy is increasing. Recently, efforts is made to improve the accuracy of PM10 predictions by using machine learning, but prediction performance is decreasing due to the particulate matter data with a large rate of low concentration occurrence. In this paper, separation prediction model by concentration is proposed to improve the accuracy of PM10 particulate matter forecast. The low and high concentration prediction model was designed using the weather and air pollution factors in Cheonan, and the performance comparison with the prediction models was performed. As a result of experiments with RMSE, MAPE, correlation coefficient, and AQI accuracy, it was confirmed that the predictive performance was improved, and that 20.62% of the AQI high-concentration prediction performance was improved.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.05a
• /
• pp.636-637
• /
• 2018

The electronic shelf label(ESL) system based on wireless communication can reduce waste of disposable paper, reduce labor force and update real time information. However, the environment in which a large number of ESL modules are installed is exposed to interference from radio frequency(RF) communications in the Industry-Science-Medical(ISM) band. In this paper, we propose an ESL system based on visible light communication to avoid congestion of ESL system using ISM band. In the proposed system, the goods information and ID transmitted from the administrator server are transmitted in the ESL Tag, and the ESL Tag identifies the ID and displays the product information. Experiments show that ESL system using visible light communication is possible.

• The Journal of Information Technology
• /
• v.6 no.4
• /
• pp.35-58
• /
• 2003

We analyze specific supplementation direction(Efficiency, Isolation, convenience, synthesis, variety, security) about system vulnerabilities of the NEIS(National Education Information System) in this research. The efficiency constructs parallel security vulnerabilities diagnosis system NEIS which the security problem prevents and checks.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.9
• /
• pp.602-608
• /
• 2017

Due to recent industry 4.0, manufacturing has changed a lot. In particular, it is necessary to control the controller and controller of the control system, to communicate various production information and measurement information, and to produce a database in accordance with the flexible production for a small quantity of various items, and to manage the trend of major parts of production facilities. In this paper, we developed a multiple wireless communication controller for small scale control system for smart factory by applying XBee and microcomputer. This controller is cheap and easy to build multi-radio communication environment of 1: N and can control and monitor control system. In addition, we tested multiple wireless communication controllers by using signal processing device and C++, and constructed network, control, and database for mechanism module, and confirmed effectiveness for industrial application.

• International Journal of Internet, Broadcasting and Communication
• /
• v.15 no.2
• /
• pp.261-267
• /
• 2023

A common approach to the problem of predicting student test scores is based on the student's previous educational history. In this study, high school transcripts of about two thousand candidates, who took the High-school Student Assessment (HSA) were collected. The data were estimated through building a regression model - Random Forest and optimizing the model's parameters based on Genetic Algorithm (GA) to predict the HSA scores. The RMSE (Root Mean Square Error) measure of the predictive models was used to evaluate the model's performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2019.05a
• /
• pp.591-593
• /
• 2019

LPWA has a small amount of data that can be transmitted at one time, but it can collect a very wide range of information, so it is suitable for gathering information of apartment meter or collecting data intermittently sent from industrial site. However, most of the application studies on LPWA are limited to outdoor, especially LOS environment, so it is difficult to collect information for application to apartment and industrial sites. In this paper, we have measured the communication coverage within the building, which is a NLOS environment, so that LPWA communication can be applied to apartments and industrial sites. For the experiment, LoRa module was created using sx1276, Class A was applied, and the spread factor was changed for each layer. As a result, in case of spreading factor 7 that shows increasing error and losses from the 7 floor, but the in case of spreading factor 12, the data could be seamlessly received even on the 9th floor without error and losses.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.17 no.10
• /
• pp.2883-2902
• /
• 2023

Since the existing anti-jamming methods, including intelligent methods, have difficulty against high-speed reactive jamming, we studied a new methodology for jamming utilization instead of avoiding jamming. Different from the existing jamming utilization techniques that harvest energy from the jamming signal as a power supply, our proposed method can take the jamming signal as a favorable factor for frequency detection. Specifically, we design an intelligent differential frequency hopping communication framework (IDFH), which contains two stages of training and communication. We first adopt supervised learning to get the jamming rule during the training stage when the synchronizing sequence is sent. And then, we utilize the jamming rule to improve the frequency detection during the communication stage when the real payload is sent. Simulation results show that the proposed method successfully combated high-speed reactive jamming with different parameters. And the communication performance increases as the power of the jamming signal increase, hence the jamming signal can help users communicate in a low signal-to-noise ratio (SNR) environment.

• Journal of the Semiconductor & Display Technology
• /
• v.16 no.4
• /
• pp.36-40
• /
• 2017

With an attempt to enhance the visibility of laser beam, we have investigated a black matrix with scattering particles by ray tracing simulations. As the scattering particle density is increased, the detected power by the receiver is increased, thereby enhancing the visibility. In reality, the visibility is reduced with increasing incident angle (away from the normal incidence) of laser beam, a phenomenon also observed by ray tracing simulations. It is due to the fact that the mean path is increased within a highly absorptive BM layer or a smaller number of rays hit the BM area when the incident angle is high. Embedding a number of scattering particles into BM may bring in crosstalk among pixels. However, it is negligible because scattered rays inside highly absorptive BM are re-scattered due to the high scattering particle density, decreasing the power of scattered rays into the active areas.

• Journal of the Semiconductor & Display Technology
• /
• v.16 no.4
• /
• pp.41-45
• /
• 2017

We have investigated the light extraction efficiency of large-area OLED lighting panels with a microlens array (MLA) or external scattering layer (ESL) by ray tracing simulation. The application of MLA and ESL to transparent OLEDs (TOLEDs) with an auxiliary metal electrode is also studied. It is found that MLA shows higher light extraction efficiency, compared with ESL. However, we have demonstrated that ESL is more suitable for TOLEDs having dual-sided equal light emission. Namely, equal light emission from the front and rear surfaces of TOLED can be achieved by increasing the scattering particle density of ESL. To compensate for a loss in light emission induced by auxiliary metal electrode, we come out with an OLED structure partially covered with MLA at the outer surface of glass substrate, which is aligned with metal electrode. With this scheme, it is observed that the light extraction efficiency can be boosted more than 20% from opaque OLED and 50% from transparent OLED.