• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.105-107
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• 2021

With the prolonged COVID-19 worldwide, it is essential to create a list of visitors when using various facilities to prevent the spread of COVID-19 and to investigate epidemiology in the event of confirmed cases. In the beginning, there were many problems due to the leakage of personal information and false preparation by making a list of visitors with a handwritten list. To compensate for the problems of handwritten lists, the KI-Pass system based on QR codes is mainly managed. However, KI-Pass systems have the disadvantages of issuing QR codes and abusing personal information. In this paper, we propose an access management system using beacon. Beacon is an close-range wireless communication device and visitors when they are near the facility and automatically registers their personal information on the cloud server for access management. It is expected that this will be effective in preventing and responding to the spread of new infectious diseases in the future.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.267-273
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• 2012

The short-range communication module was developed in this paper which is suitable for the point-to-multipoint circumstances of 40 terminals communicating frequently in about 50 meters. The media access control layer of this communication module using asynchronous time-division multiplexing provides a fast and robust performance even in the worst case of simultaneous transmission events, and low packet error rate was measured a in LOS (Line-of-sight) circumstance by adding the function of acknowledge response to media access control layer. The difference test was carried out in order to measure the performance of point-to-multipoint communication. Two communication modules are respectively measured and graphed in 10 branches to 40 branches. The communication module developed in this paper showed a faster performance than the commercial Zigbee module in the specific case presented in this paper. Especially, in over 20 branches showed wide differences of the transmission speed. This results is caused by more network overhead of Zigbee whose wider applications needs the network layer and applicaiton layer besides media access control layer. Also, the asynchronous time-division multiplexing proposed in this paper are more suitable than CSMA-CA of Zigbee module when a lot of module ought to be frequently communicated in small area.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3B
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• pp.216-223
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• 2006

The KOINONIA is developed to communicate with connection of the short-range devices by the technique of the WPAN. The piconet consists of one master and slaves above one, the multi-poconet consists of parent piconet and child piconets which is formed the basis of parent piconet. The child piconet consists of the child master and slaves. The child master takes a role of the master in the child piconet and the slave in the parent piconet. In this paper, the multi-piconet is made as above, then we estimate the max capacity of assigned CTA by level, number of slaves in child piconet. A super-frame is the maximum 65.535ms of usable capacity. Because of it is a fued number, We suggested quantitatively the fixed reduction of an usable capacity by increases of number of slave and child-master in the piconet. And we analyze the reduction of an available capacity by the increase of number of child piconet.

• Journal of Advanced Navigation Technology
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• v.21 no.1
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• pp.107-112
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• 2017

In recent years, electric shock accidents due to electric leakage currents of household appliances such as computers, TVs, refrigerators, and LED lights are continuously occurring in homes and industrial buildings. And it is not easy to check the leakage current of each household appliances connected in parallel at the rear end of the module. In addition, the leakage current flowing through the path of the normal current other than the existing current leakage circuit breakers are installed in the distribution box, only the function to cut off the power when the leakage. Therefore, there are various disasters such as electric shock and fire caused by short circuit of household appliances, and the risk of such leakage current is seriously presented. In this paper, we propose a method to implement a leakage monitoring system that can be monitored at all times using Zigbee communication based on IEEE 80215.4, which has advantages in low power and low cost among short range wireless communication systems.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.6
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• pp.88-97
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• 2009

As the development of wireless techniques, transmission technology of body area network plays an important role in realizing a welfare society by combining IT and BT when applying to vehicles. Off-body WBAN (Wireless Body Area Network) systems for video data transmission require low battery consumption and high data rate. To satisfy the requirement, UWB has been considered as a promising candidate for high rate WBAN. This paper introduces an antenna selection technique for ultra-wideband based off-body WBAN system with low complexity. In this paper, we propose an antenna selection scheme using non-coherent receiver for off-body high data rate WBAN system. The proposed receiver antenna selection method takes advantage of the characteristic of BPPM (Binary Pulse Position Modulation). With the property of BPPM, this scheme calculates the approximate SNR of the received signal with non-coherent receiver.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.6
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• pp.167-172
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• 2013

In recent years, mobile healthcare systems that transfer patient data wirelessly have been used in the medical field. However, the current messages supported to patients are difficult to satisfy the specific patients, and there is a lack of healthcare systems to help manage patients with diabetes or pregnant women on a regular basis. In this regard, this paper demonstrates that the semantic-web service to which data transfer method, application framework and networking of WPAN are applied can be implemented. In addition, it suggests common data types to integrate data from a variety of sources and provides a common framework in which information on the Web can be shared and reused in applications, businesses and communities, etc. As an example, the healthcare monitoring that can manage healthcare for pregnant women, which includes confirmation of pregnancy, periodic health management, fetal movement, prenatal care and health-related knowledge, is proposed.

• The Journal of Information Technology
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• v.5 no.1
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• pp.69-77
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• 2002

The Bluetooth is expected to be one of the most popular wireless telecommunication technology in the near future, and the protocol stack is essential to providing the various services with the Bluetooth-embedding systems or devices. The Bluetooth specification is an open, global specification defining the complete system, however, the protocol stack is usually implemented partly in hardware and partly as software running on its system, with different implementations partitioning the functionality between hardware and software in different ways. I investigate how to design and implement the Bluetooth protocol stack according to its specification. I focus on the HCI and the lower layer of the software protocol stack as a basic step for the development of our own protocol stack. As a result, paper provides how to partitioning the role of HCI layer, and how to implement the relationship between HCI packets, it's functionality and the flow control. Experiments show the discovering other Bluetooth devices and their connection. Furthermore experiments demonstrate the proper operation of data communication between the Bluetooth modules.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.4
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• pp.493-498
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• 2009

Bluetooth is a popular wireless data transmission method with low power consumption, but it has low data transmission rate. Thus, although many video stream players of a local or network file exist, there have been few players of video stream transmitted via Bluetooth. MPEG-4 AVC/H.264 codec is one of video codecs available with best compression rates for a certain quality, so a H.264 encoder seems to be adequate for video stream to be transmitted via Bluetooth. In this paper, we present a DirectShow filter based player of video stream encoded by H.264 codec, which is transmitted via Bluetooth. Details on the design and implementation of this program are described. Experimental results are shown to demonstrate the validity of the implemented program using various video samples.

• Journal of the Korea Society of Computer and Information
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• v.15 no.2
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• pp.91-98
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• 2010

In order to control moving facilities on a remote place effectively, it are required to acquire a environment informations such as images where the moving facilities are placed. However, since there is no tools to acquire such informations to the central control system based on the non-networked sensor environments, it is difficult to control the moving facilities remotely. Therefore, we design and implement the Zigbee based image transmission system and communication protocol to control the moving target remotely. The wireless control utilizing the Zigbee protocol is that electrically consumption is more small than the Bluetooth and reliability of data transmission is better. The implemented Zigbee based control systems and communication protocol have the normal and replay function for a realtime control of the moving target under the server PC and the mobile FDA with the WiFi protocol. The functional operability and performance are analyzed by a designed prototype under the wireless home network environment.

• Smart Media Journal
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• v.7 no.2
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• pp.47-53
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• 2018

Along with the development of information and communication technology, smart education that can learn without restrictions of time, place and equipment is activated even in the field of education. Although smart education is provided with content-based training solutions, construction of a system that grasps individual characteristics of learners and provides personalized learning is relatively weak. The activity of free choice is an important play activity of early childhood education, but it is not implemented efficiently by relying on the clinical observation of the teacher. If the IoT(Internet of Things) technology based on Hyper-Connected is applied to free-choice activities, it is possible to provide the child's personalized activity type and play-form analysis based on objective and stylized data. In this paper, we design and implement a system to monitor the child's activity of free choice by building an IoT environment that is based on open source hardware. The proposed system provides children's activity information as objective data and will be used as teacher's work mitigation and custom training material for each child.