• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.814-821
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• 2012

We propose a network processor called an OmniFlow processor capable of wire-speed flow management by a hardware-based flow admission control(FAC) in this paper. Because the OmniFlow processor can set up and release a wire-speed connection for flows, the update period of flows can be set to a short time, and only active flows can be effectively managed by terminating a flow that does not have a packet transmitted within this period. Therefore, the FAC can be used to provide a reliable transmission of UDP as well as TCP applications. This processor is fabricated in 65nm CMOS technology, and total gate count is 25 million. It has 40 Gb/s throughput performance in using the 32 RISC cores when maximum operating frequency is 555MHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2B
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• pp.296-301
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• 2010

Radio frequency identification(RFID) system can identify an object using wireless transmission. RFID applications are numerous and far reaching. The most interesting and widely used applications are supply chain management for companies. Currently, RFID tags must be detached or killed for security and privacy reasons when tagged objects are purchased. In this paper, we present a new architecture that transfers information about products from the electronic product code information services (EPCIS) server of a company to an individual's personal purchases management (PPM) server when products with RFID codes are sold. It solves the security and privacy issues without detaching the tag. Moreover, the PPM server described in this paper allows customers to handle the expiration dates, updates, location management, and group management of products.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1B
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• pp.53-60
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• 2007

We investigate the end-to-end delay bounds in large scale networks with Differentiated services (DiffServ) architecture. It is generally understood that networks with DiffServ architectures, where packets are treated according to the class they belong, can guarantee the end-to-end delay for packets of the highest priority class, only in lightly utilized cases. We focus on tree networks, which are defined to be acyclic connected graphs. We obtain a closed formula for delay bounds for such networks. We show that, in tree networks, the delay bounds exist regardless of the level of network utilization. These bounds are quadratically proportional to the maximum hop counts in heavily utilized networks; and are linearly proportional to the maximum hop counts in lightly utilized networks. Considering that tree networks, especially the Ethernet networks are being accepted more and more for access networks as well as provider networks, we argue that based on these delay bounds DiffServ architecture is able to support real time applications even for a large network. Throughout the paper we use Latency-Rate (LR) server model, with which it has proven that FIFO and Strict Priority are LR servers to each flows in certain conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.41-48
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• 2017

Recently, there has been a lot of ongoing research regarding financial transactions and payments due to the emergence of financial technology (FinTech). Payments have been processed through cash and credit cards, and payment methods have been simplified and are more convenient, with mobile payment via mobile cards and mobile phones. This study offers a new mobile payment method by using a mobile phone instead of a card reader or terminal. For payments, authentication is processed with the user's biometrics and a built-in fingerprint scanner, and the payment is processed after receiving an authentication code issued by the authorizing institution to confirm the user's identity. User biometrics and payment information is secured from any kind of malicious hacker by saving it in a Fast Identity Online (FIDO) Trusted Execution Environment (TEE) section in a smartphone. Regarding key security, every key is securely created in the FIDO TEE section, providing secure mobile payment by neutralizing various malicious attacks, including sniffing and the man-in-the middle attack.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.5 no.1
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• pp.65-70
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• 2011

A communication is one of the most important factors for the human beings. Therefore, people who have some problems in communication need an Augmentative & Alternative Communication (AAC) intervention to live in the human societies and several AAC systems have been developed to help the people. Lately, smart-phone is widely used to people as a communication device which can connect between persons. It can provide many useful methods and Apps to the user. If the AAC system is unified to the smart-phone, it is very effective device to the people with disabled because they can reduce the excessive expense and easily accommodate themselves to the AAC system. In this paper, an AAC program which is installed in the smart-phone or tablet PC is introduced. It has basic AAC solutions and can send SMS message to other people. We expect that the developed device can help the communication of the people with disabled and solve the social isolation of the disabled person.

• Journal of Broadcast Engineering
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• v.8 no.3
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• pp.228-237
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• 2003

Eureka-147 DAB(Digital Audio Broadcasting) system on which DMB(Digital Multimedia Broadcasting) system is based, was designed for the requirements of CD qualify audio with ${10}^{-4}$ bit error rate. Audio program may be primary service in DAB system, but multimedia program can be primary service in DMB system. Therefore, the bit error rate required must be below ${10}^{-7}$∼${10}^{-8}$ to transmit multimedia data via DMB channel. In order to meet the requirements and keep backward compatibility of DAB system we propose an outer channel coding scheme using Reed-Solomon coding and convolutional interleaving. This paper shows the simulation results for DMB channel performance based on mobile channel model. Also, it describes the needs and the effects of the outer channel coding.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.181-186
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• 2017

Child crimes such as child abduction and lost children(MIA) have long been pointed out as social problems. However, there are few ways to solve these problems. According to MIA statistics, about 3,000 babies are lost each year. This paper presents a study on prevention of lost children ratio using mobile LBS in order to reduce the incidence of lost children ratio in dense space. First, we input the personal information of the child and the contact information of the parent. Second, we use the Google Maps API to get the location (parent's location, child's location) information. Third, the personal information of the child and the parent is indicated in the obtained location information. In future research, based on SNS, we will carry out research on sending child location information and parent location information via SMS. It is expected that the prevention system of lost child using LBS and SNS will make a great contribution to reduce the lost children ratio in the ubiquitous society.

• Journal of the Korea Society of Computer and Information
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• v.19 no.7
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• pp.59-70
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• 2014

This paper propose a new wireless multi-hop routing protocol that takes the hierarchical mesh of the hybrid WMN into account. WMN that is possible to provide various applications of wireless networks still has many open issues that should be solved despite the studies carried out over a decade. Especially, in routing protocol area, a problem degrading the routing efficiency by applying one of the routing protocols, which are designed for the MANET, to the hybrid WMN be solved above all. For the improvement of the routing performance, both good routing protocol and metric are essential. However, the recent studies are only concentrated in routing metric by use of the cross-layer design. Therefore, this paper is dedicated to the routing protocol that is essential for the performance of the routing but needed more studies. The proposed protocol in this paper is reactive, and designed to reorganize the hybrid WMN with several pseudo domains, and carry out domain-based route decision. By the simulation result for the performance analysis of the proposed protocol, the average delay for the route decision was decreased by 43% compared to AODV that is the typical reactive protocol.

• 전자공학회논문지 IE
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• v.48 no.4
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• pp.61-68
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• 2011

As business management has a high level of dependence on Informational Technology (IT), protecting assets of a company from disaster is one of the most important thing that IT operating managers should consider. Because data or information is a major source of operation of the company, data security is the first priority as an aspect of continuity of business management. Therefore, this paper will realize disaster recovery system, which is suspended because of disaster, based on cloud computing system. Realized High Available Replicate System applied a method of multi thread target database to improve Replicate performance, and real time synchronize technology can improve efficiency of network. From Active to Active operation, it maximizes use of backup system, and it has a effect to disperse load of source database system. Also, High Available Replicate System realized consistency verification mechanism and monitoring technique. For Performance evaluation, High Available Replicate System used multi thread method, which shows more than threefold of replicate performance than single thread method.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.168-180
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• 2018

Due to the spread of mobile devices and the introduction of high-quality services, mobile traffic is expected to increase sharply and overload of cellular networks is expected. D2D communication is a way to reduce the load and evolve to 5th generation. Since D2D communication directly communicates between the terminals, it can reduce the overload of the cellular network and improve energy efficiency, data rate and network performance. This paper proposes a D2D handover scheme for D2D communication in cellular networks. The cellular network is a 3GPP EPS, and the proposed D2D handover method improves the existing EPS handover process considering compatibility between existing EPS and D2D communication. We also demonstrate the superiority of the proposed handover scheme using the network simulator ns-3. Simulation results show that the proposed handover scheme is superior to existing handover methods in terms of CUE variation, packet transmission delay time, and throughput.