• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.57-63
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• 2016

This paper describes implementation of the RF frequency synthesizer with $0.18{\mu}m$ silicon CMOS technology being used as an application of the IEEE802.15.4g SUN sensor node transceiver modules. Design of the each module like VCO, prescaler, 1/N divider, ${\Delta}-{\Sigma}$ modulator, and common circuits of the PLL has been optimized to obtain high speed and low noise performance. Especially, the VCO has been designed with NP core structure and 13 steps cap-bank to get high speed, low noise, and wide band tuning range. The output frequencies of the implemented synthesizer is 1483MHz~2017MHz, the phase noise of the synthesizer is -98.63dBc/Hz at 100KHz offset and -122.05dBc/Hz at 1MHz offset.

• Journal of Convergence for Information Technology
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• v.10 no.6
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• pp.41-48
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• 2020

The sensor nodes in underwater IoT networks have practical limitations in power supply. Thus, the reduction of power consumption is one of the most important issues in underwater environments. In this regard, AMC(Adaptive Modulation and Coding) techniques are used by using the relation between SNR and BER. However, according to our hands-on experience, we observed that the relation between SNR and BER is not that tight in underwater environments. Therefore, we propose a deep learning based MLP classification model to reflect multiple underwater channel parameters at the same time. It correctly predicts BER with a high accuracy of 85.2%. The proposed model can choose the best parameters to have the highest throughput. Simulation results show that the throughput can be enhanced by 4.4 times higher than the conventionally measured results.

• Convergence Security Journal
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• v.8 no.4
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• pp.73-80
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• 2008

In this paper, we developed a WMS (Warehouse Management System) Simulator. There is no Simulator that supports optimized design for Warehouse, consider goods which storage in warehouse and using RFID and USN based on cable wireless network. Also, there is no tool for monitoring which decides delivery time with information about temperature, humidity and illumination, after goods are stocked into warehouse. In this paper, WMS Simulator Implements function of drawing a blueprint. The Simulator that can analyze moving information of Palette with RFID tags and the change about temperature, humidity and illumination is developed in this paper. Inventory accuracy, space equipment practical use, and decreasing of picking time, faulty storage and product loss by product processing ability elevation are expected by designing the way of operating of warehouse for most suitable use of system in physical distribution through these treatise.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.4
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• pp.107-114
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• 2014

Things in the IoT(Internet of Things) make various services by exchanging information over networks. The IoT includes many types of WSNs(Wireless Sensor Networks) that consists of spatially distributed wireless sensor nodes and operates with the various purposes with useful technologies such as identification, sensing and communication. Typically, Zigbee network composed of low-cost and lowpower devices is mainly used for wide-area monitoring and remote device control systems. The IoT composed of various WSNs cannot interoperate among networks because of heterogeneous communication protocol and different data representation of each network, but can facilitate interconnection and information exchange among networks via the DDS, which is communication middleware standard that aims to enable real-time, high performance and interoperable data exchanges. In this paper, we proposed design of Zigbee Adaptor for two-way interoperation and data exchange between Zigbee network and other networks in the IoT. Zigbee Adaptor communicates with Zigbee network according to the Zigbee protocol and communicates with external networks via DDS. DDS-based Zigbee Adaptor can facilitate interoperation between a Zigbee network and external networks by systematic cooperation among its components.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.109-116
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• 2014

In recent, ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart phone, notebook computer, printer and portable multimedia devices. Accordingly, studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi device using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band causes serious network performance deterioration of wireless sensor networks. This paper examined a method of identifying channel status to avoid interference among wireless communication devices using IEEE 802.11b (Wi-Fi) and other ISM bands during communication among IEEE 802.15.4 based wireless sensor network nodes in ISM band. To identify channels occupied by Wi-Fi traffic, various studies are being conducted that use the RSSI (Received Signal Strength Indicator) value of interference signal obtained through ED (Energy Detection) feature that is one of IEEE 802.15.4 transmitter characteristics. This paper examines an algorithm that identifies the possibility of using more accurate channel by mixing utilization of interference signal and RSSI mean value of interference signal by wireless sensor network nodes. In addition, it verifies such algorithm by using OPNET Network verification simulator.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.639-647
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• 2023

A variety of communications are developed and advanced by integration of wireless and wire connections with heterogeneous system. Traditional technologies are mainly focus on information technology based on computer techniques in the field of industry, manufacture and automation fields. As new technologies are developed and enhanced with traditional techniques, a lot of new applications are emerged and merged with existing mechanism and skills. The representative applications are IoT(Internet of Things) services and applications. IoT is breakthrough technologies and one of the innovation industries which are called 4 generation industry revolution. Due to limited resources in IoT such as small memory, low power and computing power, IoT devices are vulnerable and disclosed with security problems. In this paper, we reviewed and analyzed security challenges, threats and requirements under IoT service.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.2 s.3
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• pp.43-54
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• 2003

As the demand for ubiquitous mobile wireless Internet grows, vehicles are receiving a lot of attention as new networking platforms. The demand for 4G all-IP networks encourages vehicle networks to be connected using IPv6. By means of network mobility (NEMO) support, we can connect sensors, controllers, local ,servers as well as passengers' devices of a vehicle to the Internet through a mobile router. The mobile router provides the connectivity to the Internet and mobility transparency for the rest of the mobile nodes of an in-vehicle nv6 network. So, it is .important for the mobile router to assure reliable connection and a sufficient data rate for the group of nodes behind it. To provide reliability, this paper proposes an adaptive multihoming architecture of multiple mobile routers. Proposed architecture makes use of different mobility characteristics of different vehicles. Simulation results with different configurations show that the proposed architecture increases session preservation thus increases reliability and reduces packet loss. We also show that the proposed architecture is adaptive to heterogeneous access environment which provide different access coverage areas and data rates. The result shows that our architecture achieves sufficient data rates as well as session preservation.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.5
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• pp.144-151
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• 2017

In this paper, the antenna for parking management using wireless communication in outdoor parking environment was proposed. The proposed antenna was miniaturized by using parasitic element to reduce the size of the radiating element of the basic ${\lambda}/2$ microstrip antenna. The dimensions of the proposed antenna are $35mm{\times}35mm{\times}20.1mm$ that is 98.7% smaller than $309.1mm(0.46{\lambda}){\times}296.1mm(0.441{\lambda}){\times}20.1mm(0.029{\lambda})$ of the basic ${\lambda}/2$ microstrip antenna. The electrical characteristics of the antenna are 1.1 dBi at the center frequency of 447 MHz, an omni-directional radiation pattern on the E-plane, and $87.5^{\circ}$ of HPBW on the H-plane. The miniaturized ${\lambda}/4$ folded microstrip antenna using parasitic element has proved to be easy to mount on the wireless repeater, the sensor node installed on the ground, and the strop bar in the outdoor parking environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.661-667
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• 2018

Recently, the smart home market is growing due to the development of wireless communication technology and sensor devices, and various devices are being utilized. Such an IoT environment collects various vast amount of device information for intelligent services, receives services based on user information, controls various devices, and provides communication between different types of devices. However, with this growth, various security threats are occurring in the smart home environment. In fact, Proofpoint and HP warned about the cases of damage in a smart home environment and the severity of security vulnerabilities, and cases of infringement in various environments were announced. Therefore, in this paper, we have studied secure mutual authentication method between smart nodes used in smart home to solve security problems that may occur in smart home environment. In the case of the proposed thesis, security evaluations are performed using random numbers and frequently updated session keys and secret keys for well-known vulnerabilities that can occur in IoT environments and sensor devices such as sniffing, spoofing, device mutual authentication, And safety. In addition, it is confirmed that it is superior in security and key management through comparison with existing smart home security protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.5
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• pp.271-280
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• 2014

In wireless sensor networks, there have been two methods for sensing continuously moving object tracking: user-query based method and periodic report based method. Although the former method requires overhead for user query rather than the latter method, the former one is known as an energy-efficient method without transferring unnecessary information. In the former method, a virtual tree, consisting of sensor nodes, is exploited for the user querying and sensor reporting. The tree stores the information about mobile objects; the stored information is triggered to report by the user query. However, in case of fast moving object, the tracking accuracy reduces due to the time delay of end-to-end repeated query. To solve the problem, we propose a query relaying method reducing the time delay for mobile object tracking. In the proposed method, the nodes in the tree relay the query to the adjacent node according to the movement of mobile object tracking. Relaying the query message reduces the end-to-end querying time delay. Simulation results show that our method is superior to the existing ones in terms of tracking accuracy.