• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.640-647
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• 2014

The WBAN technology means a short distance wireless network which provides each device's interactive communication by connecting devices inside and outside of body located within 3 meters. It is necessary to develop core technology that the WBAN middleware and application service for WBAN sensor network. A device for gathering patient's biometric information was used zigbex of Hanbaek electronics and we designed the message structure which is collected the biometric information. The gateway design and implementation for the WBAN environment. The embedded system was HBE-empos II of Hanbaek electronics and the WBAN network is implemented to BNC and BN that used for hbe-ubi-zigbex. It was confirmed that the proposed sensor gateway could be used for the interconnection of the proposed system with other networks.

• Journal of Information Technology Services
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• v.3 no.2
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• pp.119-127
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• 2004

A mobile ad hoc network(MANET) is a network where a set of mobile devices communicate among themselves using wireless transmission without the support of a fixed network infrastructure. The use of wireless links makes MANET susceptible to attack. Eavesdroppers can access secret information, violating network confidentiality, and compromised nodes can launch attack from within a network. Therefore, the security for MANET depends on using the cryptographic key, which can make the network reliable. In addition, because MANET has a lot of mobile devices, the authentication scheme utilizing only the symmetric key cryptography can not support a wide range of device authentication. Thereby, PKI based device authentication technique in the Ad Hoc network is essential and the paper will utilize the concept of PKI. Especially, this paper is focused on the key management technique of PKI technologies that can offer the advantage of the key distribution, authentication, and non-reputation, and the issuing and managing technique of certificates based on clustering using Threshold Cryptography for secure communication in MANET.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.18-25
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• 2020

With the development of water internet technology, data communication between objects is expanding. Research related to data communication technology between vehicles that incorporates related technologies into vehicles has been actively conducted. For data communication between mobile terminals, data stability, reliability, and real-time performance must be guaranteed. The 5 GHz Wi-Fi band, which is advantageous in bandwidth, communications speed, and wireless saturation of the wireless network, was selected as the data communications network between vehicles. This study analyzes how to design and implement a 5 GHz Wi-Fi network in a vehicle network. Considering the characteristics of the mobile communication terminal device, a continuous variable communications structure is proposed to enable high-speed data switching. We simplify the access point access procedure to reduce the latency between wireless terminals. By limiting the Transmission Control Protocol Internet Protocol (TCP/IP)-based Dynamic Host Configuration Protocol (DHCP) server function and implementing it in a broadcast transmission protocol method, communication delay between terminal devices is improved. Compared to the general commercial Wi-Fi communication method, the connection operation and response speed have been improved by five seconds or more. Utilizing this method can be applied to various types of event data communication between vehicles. It can also be extended to wireless data-based intelligent road networks and systems for autonomous driving.

• International journal of advanced smart convergence
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• v.8 no.2
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• pp.109-115
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• 2019

Currently, LPWA(Low Power Wide Area) communication technology is widely used due to the development of IoT(Internet of Things) technology. Among the LPWA technologies, LoRaWAN(Long Range Wide Area Network) is widely used in many fields due to its wide coverage, stable communication speed, and low-cost modem module prices. In particular, LoRa(Long Range) can easily construct LoRaWAN with a dedicated gateway. So many organizations are building their own LoRaWAN-based networks. The LoRaWAN Gateway receives the LoRa packet transmitted from an End-device installed in the adjacent location, converts it into the Internet protocol, and sends the packet to the final destination server. Current LoRa Gateway uses a single-hop method, and each gateway must include a communication network capable of the Internet. If it is the mobile communication(i.e., WCDMA, LTE, etc.) network, it is required to pay the internet usage fee which is installed in each gateway. If the LoRa communication is frequent, the user has to spend a lot of money. We propose an idea on how to design a multi-hop protocol which enables packet routing between gateways by analyzing the LoRaWAN communication method implemented in its existing single-hop way in this paper. For this purpose, this paper provides an analysis of the standard specification of LoRaWAN and explains what was considered when such protocol was designed. In this paper, two gateways have been placed based on the functional role so as to make the multi-hop protocol realized: (i) hopping gateway which receives packets from the end-device and forwards them to another gateway; and (ii) main gateway which finally transmits packets forwarded from the hopping gateway to the server via internet. Moreover, taking into account that LoRaWAN is wireless mobile communication, a level-based routing method is also included. If the protocol proposed by this paper is applied to the LoRaWAN network, the monthly internet fee incurred for the gateway will be reduced and the reliability of data transmission will be increased.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.41-46
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• 2016

Recently, many domestic and foreign corporates are concentrating in investment to wearable devices and users are provided with various service based on wearable devices 26% more than compared to last year. It is widely used in previous healthcare, smart work, smart home environment, and it is now introduced to get connection to fused service environment. However, as products of G company are commercialized, the security issue of personal information is causing dispute in society, and the danger of data management and security regarding telecommunication is increasing. Also, because the password system used in previous wireless environment is still in use, there are possible vulnerability considering the new and mutant security threat. This thesis conducted study about protocols that can exercise safe telecommunication in the basis of wearable devices. In the registration and certification process, the signature value is created based on the code value. The telecommunication method is designed to conduct safe telecommunication based on the signature value. As for the attack method occurring in the wearable device environment, the safety was analyzed and conducted performance evaluation of previous password system and proposal system, and verified about 14% of efficiency.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.125-134
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• 2009

Ubiquitous are not courted in time and place of users and must offer service in network freely. There is telematics by representative application service during it. telematics service must provide service that is personalized according to time and place. Also, user who use telematics service must offer service that can use automatically even if do not request service. Therefore, in the paper wish to embody service discovery way design in telematics environment because treatise that see uses UPnP through PDA that is user Mobile terminal. PDA connected by local server of telematics service point and Bluetooth communication, and use finding UPnP device and service that is linked with local server using UPnP. Design UPnP device that provide service to user in telematics environment. Construct telematics service test bed to test service discovery. Because constructed system applies UPnP on Bluetooth communication base, service discovery system implementation and test.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.3
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• pp.131-139
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• 2001

As increasing the accident of Distribution Transformer (DT), we need to manage them efficiently. In this paper, we discusses with the possibility of the diagnostic technique for distribution transformer using relative ageing rate calculation in this paper. The relative ageing rate of the DT could be calculated from the measured top oil temperature, ambient temperature and load current. In order on apply the proposed diagnostic technique we developed an on line Monitoring and Diagnostic System (MDS) which has hardware and software part. Diagnostic device is developed to measure the state information of DT and to send them with R/F(radio frequency) communication. Host computer monitors and saves the receive data. The database is constructed from the data of distributed DT and it is used for estimating loss-of-life in the MDS.

• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.9-14
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• 2018

Recently, as the internet speed is getting faster, in the cloud environment, the service receiving device is changing from a general PC to a compact device such as a mobile phone or a tablet PC. Since handheld devices such as mobile phones or tablet PCs are often used in wireless rather than wired, there are many problems that personal information may be exposed maliciously from a third party. In this paper, we propose a user privacy protection scheme through a duplicate duplicate key generation process which can safely protect user 's privacy from third party among cloud services being served through various wireless media. The proposed scheme is used to synchronize the duplicated key between the server and the intermediary device, and aims at shortening the time of the authentication process protecting the user 's privacy. In this case, the proposed scheme uses Interleave() function and random number to synchronize the server and the intermediary device, so it can safely prevent the malicious attack of the third party.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.724-729
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• 2008

This paper presents the calculation of the required bandwidth of common frequency bandwidth applying queueing theory for maximizing the efficiency of frequency resource of WPAN(Wireless Personal Area Network) based Digital acoustic and communication devices. It assumed that LBT device(ZigBee) and FH devices (DCP, RFID and Bluetooth) coexist in the common frequency band for WPAN based Digital acoustic and communication devices. Frequency hopping (FH) and listen before talk (LBT) have been used for interference avoidance in the short range device (SRD). The LBT system transmits data after searching for usable frequency bandwidth in the radio wave environment. However, the FH system transmits data without searching for usable frequency bandwidth. The queuing theory is employed to model the FH and LBT system, respectively. As a result, the throughput for each channel was analyzed by processing the usage frequency and the interval of service time for each channel statistically. When common frequency bandwidth is shared with SRD using 250mW, it was known that about 35 channels were required at the condition of throughput 84%, which was determined with the input condition of Gaussian distribution implying safety communication. Therefore, the common frequency bandwidth is estimated with multiplying the number of channel by the bandwidth per channel. These methodology will be useful for the efficient usage of frequency bandwidth.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.783-798
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• 2004

An e-business client application in ubiquitous mobile computing environment may become disconnected from the enterprise server due to broken communication connections caused by the limitation of mobile computing environments(limited battery life of the mobile device, low bandwidth communication, incomplete wireless communication infrastructure, etc). It Is even Possible that mobile client application Intentionally operates in disconnected mode to reduce communication cost and the power consumption of the mobile device. We use “data hoarding” as a means of providing local autonomy to allow transactions to be processed and committed on the mobile host despite of disconnection. The key problem to this approach is the synchronization problem that serialize potentially conflicting updates from disconnected clients on master objects of the server database. In this paper, we present a new transaction synchronizing method that splits a transaction into a set of independent component transactions and give the synchronization priority on each component taking the possibility of use and conflicts in the server into consideration. Synchronization is performed component by component based un synchronization priority. After the Preferred component of a no bile transaction succeeds in synchronization with the server, the mobile transaction can pre-commit at server. A pre-committed transaction's updated value is made visible at server before the final commit of the transaction. The synchronization of the component with low synchronization priority can be delayed in adaption to wireless bandwidth and computing resources. As a result, the availability of important data updated by mobile client is increased and it can maximize the utilization of the limited wireless bandwidth and computing resources.