• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.1
• /
• pp.231-237
• /
• 2020

In this paper, we implemented a home IoT system based on MQTT protocol. In this system, data are collected from sensors in real time and transmitted to the server system. Based on collected data, home devices could be controlled automatically or manually. By using the MQTT protocol, we were able to see the data values of sensors collected in real time according to the topic setting. We implemented a system that automatically sets up home devices based on topic data, and it worked. The system is expected to be useful in applications that require monitoring and tracking of data in real time.

• International Journal of Computer Science & Network Security
• /
• v.22 no.10
• /
• pp.191-200
• /
• 2022

Constrained Application Protocol (CoAP) is a standardized protocol by the Internet Engineering Task Force (IETF) for the Internet of things (IoT). IoT devices have limited computation power, memory, and connectivity capabilities. One of the significant problems in IoT networks is congestion control. The CoAP standard has an exponential backoff congestion control mechanism, which may not be adequate for all IoT applications. Each IoT application would have different characteristics, requiring a novel algorithm to handle congestion in the IoT network. Unnecessary retransmissions, and packet collisions, caused due to lossy links and higher packet error rates, lead to congestion in the IoT network. This paper presents an adaptive congestion control protocol for CoAP, Adaptive Congestion Control with a Backoff algorithm (ACCB). AACB is an extension to our earlier protocol AdCoCoA. The proposed algorithm estimates RTT, RTTVAR, and RTO using dynamic factors instead of fixed values. Also, the backoff mechanism has dynamic factors to estimate the RTO value on retransmissions. This dynamic adaptation helps to improve CoAP performance and reduce retransmissions. The results show ACCB has significantly higher goodput (49.5%, 436.5%, 312.7%), packet delivery ratio (10.1%, 56%, 23.3%), and transmission rate (37.7%, 265%, 175.3%); compare to CoAP, CoCoA+ and AdCoCoA respectively in linear scenario. The results show ACCB has significantly higher goodput (60.5%, 482%,202.1%), packet delivery ratio (7.6%, 60.6%, 26%), and transmission rate (40.9%, 284%, 146.45%); compare to CoAP, CoCoA+ and AdCoCoA respectively in random walk scenario. ACCB has similar retransmission index compare to CoAp, CoCoA+ and AdCoCoA respectively in both the scenarios.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.1C
• /
• pp.24-33
• /
• 2012

Recently, the ultra-lightweight authentication RFID protocol that can actually implement on the RFID Tag is one among authentication protocols getting a concern, but recently many problems were clarified of the feature becase of the protocol which doesn't use the security algorithm. In this paper, we analyzed the problem of the ultra-lightweight authentication protocols and propose the design of ultra-lightweight RFID authentic ation protocols improving the index processing techniques. Because of improving the index processing technique in the method sending the Server authentication message to the authenticated tag, the proposed protocol is strong against the active attack which Li presents. Besides, the proposed protocol has the buffer storage of the keys and index and is strong against the asynchronous attack.

• Imaging Science in Dentistry
• /
• v.52 no.4
• /
• pp.393-398
• /
• 2022

Purpose: This study proposed a generative adversarial network (GAN) model for T2-weighted image (WI) synthesis from proton density (PD)-WI in a temporomandibular joint(TMJ) magnetic resonance imaging (MRI) protocol. Materials and Methods: From January to November 2019, MRI scans for TMJ were reviewed and 308 imaging sets were collected. For training, 277 pairs of PD- and T2-WI sagittal TMJ images were used. Transfer learning of the pix2pix GAN model was utilized to generate T2-WI from PD-WI. Model performance was evaluated with the structural similarity index map (SSIM) and peak signal-to-noise ratio (PSNR) indices for 31 predicted T2-WI (pT2). The disc position was clinically diagnosed as anterior disc displacement with or without reduction, and joint effusion as present or absent. The true T2-WI-based diagnosis was regarded as the gold standard, to which pT2-based diagnoses were compared using Cohen's ĸ coefficient. Results: The mean SSIM and PSNR values were 0.4781(±0.0522) and 21.30(±1.51) dB, respectively. The pT2 protocol showed almost perfect agreement(ĸ=0.81) with the gold standard for disc position. The number of discordant cases was higher for normal disc position (17%) than for anterior displacement with reduction (2%) or without reduction (10%). The effusion diagnosis also showed almost perfect agreement(ĸ=0.88), with higher concordance for the presence (85%) than for the absence (77%) of effusion. Conclusion: The application of pT2 images for a TMJ MRI protocol useful for diagnosis, although the image quality of pT2 was not fully satisfactory. Further research is expected to enhance pT2 quality.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.4 no.1
• /
• pp.3-15
• /
• 2000

As an OLT in the central office controls up to 64 ONUs in the subscriber area via a passive optical splitter, the hU PON system can accomodate PTTx in a single platform with low cost. To operate the system, it is important to implement an efficient MAC protocol, however, the protocol is currently the further study area in the ITU-T 0.983.1. In this paper, we suggest the MAC protocol which is needed to send cells of ONU to upstream, and based on the ITU-T G.983.1. We survey conventional MAC protocols which are not based on G.983.1, and then formulate the minislot period and length for the grant request and determine the optimal value of each parameter. Also, we suggest a coding scheme for the grant field of the PLOAM cell and the procedure allocating optimal parameters to the ONU.

• The Journal of the Convergence on Culture Technology
• /
• v.1 no.3
• /
• pp.83-85
• /
• 2015

It has been increased that communicate each other things such as consumer electronics, mobile equipments and wearable computer with serial communication protocol. The conventional method of SPI and I2C high speed serial communication is widely used with 2 pin of clock and data pin. It has been more important than the speed of data transfer to simplify the hardware structure because the IoT components is reduced the hardware complexity. In this paper, we describe the protocol and implementation of serial data transfer with only one pin. The proposed protocol is suitable for the mobile products that send and receive the small amount of data with low speed and low power consumption.

• Smart Structures and Systems
• /
• v.14 no.1
• /
• pp.1-16
• /
• 2014

In this work, we address the so-called sensor reachback problem for Wireless Sensor Networks, which consists in collecting the measurements acquired by a large number of sensor nodes into a sink node which has major computational and power capabilities. Focused on applications such as Structural Health Monitoring, we propose a cooperative communication protocol that exploits the spatio-temporal correlations of the sensor measurements in order to save energy when transmitting the information to the sink node in a non-stationary environment. In addition to cooperative communications, the protocol is based on two well-studied adaptive filtering techniques, Least Mean Squares and Recursive Least Squares, which trade off computational complexity and reduction in the number of transmissions to the sink node. Finally, experiments with real acceleration measurements, obtained from the Canton Tower in China, are included to show the effectiveness of the proposed method.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.1
• /
• pp.87-92
• /
• 2020

Various devices, which are powerful computer and low-performance sensors, is connected to IoT network. Accordingly, applying mutual authentication for devices and data encryption method are essential since illegal attacks are existing on the network. But cryptographic methods such as symmetric key and public key algorithms, hash function are not appropriate to low-performance devices. Therefore, this paper proposes blockchain-based lightweight IoT mutual authentication protocol for the low-performance devices.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.1
• /
• pp.196-201
• /
• 2018

Recently, various infrastructure-less IoT networking schemes have been studied to construct local IoT networks based on self-organization. This is, because RPL protocol, which is to support infrastructure based network construction is used to construct local IoT networks. Thus, a self-organization networking and ad hoc path between client and server in local IoT networks is not supported in basis RPL protocol. In this paper, we propose a self-organization networking scheme which support infrastructure-less based IoT network construction in low-power and lossy network based IoT environments consisting of IoT devices with the constrained feature, such as low power, the limited transmission rate and low computing capacity. Through simulation, we show that the proposed self-organization networking scheme improves the performance, in terms of the number of packets generated for end-to end data transmission and the end-to-end delay, compared to basis RPL protocol.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.15 no.1
• /
• pp.21-28
• /
• 2019

Internet of Things(IoT) is a technology or environment that collects data by attaching sensors to objects and transmits the collected information to each other through wired / wireless communication in real time. It is expected that when the Internet of objects is activated, many objects can identify and recognize each other by themselves and provide various services to facilitate our lives through mutual information exchange. In addition, the internet market for things is growing rapidly each year, and various IT technologies are expected to converge. In the Internet environment of objects, data exchange technology between object devices, that is, message protocol, is classified as one of important technologies. In this paper, we examine various lightweight message protocols suitable for the Internet environment of objects, and compare the reliability of the CoAP protocol structure with the MQTT protocol for a limited environment. Finally, we confirm the reliability of TCP / TLS and WebSockets-based CoAP transmission protocol of IETF's CoRE WG that can use various transport layers other than UDP in Internet environment including cloud infrastructure.