• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.533-535
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• 2017

MQTT는 TCP/IP 계층 위에서 3가지의 QoS level을 제공하여 메시지 전달의 신뢰성을 보장한다. 하지만, 노드에서 동시다발적으로 메시지가 송수신되는 환경의 경우 QoS level에 대한 전달 방식으로 인해 메시지 손실이 발생할 수 있다. 본 논문에서는 MQTT에서 동시다발적으로 메시지가 송수신되는 실험 환경을 구축하여 QoS level 변화에 따른 메시지 신뢰성을 확인한다. 이를 위해 publisher 수와 메시지의 전송 주기를 변화시켜 subscriber 측면에서 메시지 수신율을 분석한다. 실험 결과 publisher의 수가 증가하거나 메시지의 전송 주기가 빠를수록 QoS level 0을 제외한 1, 2의 메시지 수신율이 감소됨을 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.57-60
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• 2001

This paper has studied the WAP packet transmission time, using WTP SAR algorithm. One method that is improved transfer ability, SAR fragmented WTP total message down from upper layer and then packet is transmitted to RLP frame time slot. In this paper, we analysis the transmission time of WAP packet with variable HLP layer size on the CDMA wireless channel for next generation systems as well as PCS, DCS. From the results, we can obtain the WAP packet transmission time and optimal WTP packet size.

• IEIE Transactions on Smart Processing and Computing
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• 제3권5호
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• pp.298-305
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• 2014

In this study, a novel Randomly Shifted Certification Authority Authentication protocol was used in ad hoc networks to provide authentication by considering the MAC layer characteristics. The nodes achieve authentication through the use of public key certificates issued by a CA, which assures the certificate's ownership. As a part of providing key management, the active CA node transfers the image of the stored public keys to other idle CA nodes. Finally the current active CA randomly selects the ID of the available idle CA and shifts the CA ownership by transferring it. Revoking is done if any counterfeit or duplicate non CA node ID is found. Authentication and integrity is provided by preventing MAC control packets, and Enhanced Hash Message Authentication Code (EHMAC) can be used. Here EHMAC with various outputs is introduced in all control packets. When a node transmits a packet to a node with EHMAC, verification is conducted and the node replies with the transmitter address and EHMAC in the acknowledgement.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.625-628
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• 2011

Dynamic sensor network(DSN) technology which is based on swarming flight type air node offers analyzed and acquired information on target data gathered by air nodes in rotation flight or 3 dimension array flight. Efficient operation of dynamic sensor network based on air node is possible when problems of processing time, data transmission reliability, power consumption and intermittent connectivity are solved. Delay tolerant network (DTN) can be a desirable alternative to solve those problems. DTN using store-and-forward message switching technology is a solution to intermittent network connectivity, long and variable delay time, asymmetric data rates, and high error rates. However, all processes are performed at the bundle layer, so high power consumption, long processing time, and repeated reliability technique occur. DSN based on swarming flight type air node need to adopt store-and-forward message switching technique of DTN, the cancelation scheme of repeated reliability technique, fast processing time with simplified layer composition.

• ETRI Journal
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• 제19권3호
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• pp.202-227
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• 1997

This paper describes the development of the CDMA mobile station to support non-speech, mobile office services such as data, fax, and short message service in addition to voice. We developed some important functions of layer 2 and layer 3. To provide non-speech services, we developed a terminal adapter and user interface software. The description of development process, software architecture and external interfaces required to provide such services is given. The description of a TTA-62 message analysis tool, a mobile station monitoring software, and an automatic test system developed for integration tests and performance measurements is also given.

• 한국정보통신학회논문지
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• 제14권8호
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• pp.1855-1860
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• 2010

본 논문은 웹 서비스 표준을 이용하여 안전한 메시지 전송을 위한 웹서비스 시스템을 구현하였다. 본 시스템은 싱글사인온 모듈과 SSL(Secure Socket Layer) 모듈과 안전한 메시지 모듈로 구성되어 있다. 이들 모듈들을 적용하기 위해 가격비교사이트를 대상모델로 하여 설계하였다. 싱글사인온 모듈은 SAML(Security Assertion Markup Language) 표준을 사용하였으며, 또한 권한부여와 인증을 제공한다. SSL 모듈은 종단 간에 메시지 암호화를 처리하기 때문에, 시스템의 메시지를 안전하게 전송한다. 또한 안전한 메시지 모듈은 웹 서비스 보안 표준을 따르는 XML암호화와 서명을 적용하였다.

• 정보보호학회논문지
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• 제24권5호
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• pp.975-985
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• 2014

스마트폰을 사용한 전자금융거래가 증가하면서, 스마트폰을 대상으로 하는 새로운 위협들이 증가하고 있다. 그중에서도 최근, 가장 위협이 되고 있는 스미싱은 갈수록 수법이 교묘해지고, 다양해지고 있다. 금융기관들은 증가하는 스미싱 위협에 대응하기 위한 방안으로 "알 수 없는 출처"의 설정을 통해 어플리케이션 설치를 차단하는 방법과 스미싱 탐지 어플리케이션의 설치를 권고하고 있다. 하지만 현재까지의 대응방안이 갖고 있는 한계적 문제로 인해 효과적으로 스미싱에 대응하지 못하고 있다. 본 논문에서는 안드로이드 RIL(Radio Interface Layer)에서 사용자 기기에 수신된 문자메시지를 수집하고, DB(Database) 내에 문자메시지가 저장되었는지 검사하여, 악성코드의 설치여부를 판단한다. 그리고 커널레벨에서의 시스템 콜 후킹을 통해 악성코드가 전송하는 문자메시지를 차단하는 기법을 제안한다. 또한 실제 구현을 통하여 기기에 적용이 가능함을 증명하였다.

• Wind and Structures
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• 제20권6호
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• pp.793-810
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• 2015

Tests were conducted at the Florida International University (FIU) Wall of Wind (WOW) to investigate the susceptibility of Variable Message Signs (VMS) to wind induced vibrations due to vortex shedding and galloping instability. Large scale VMS models were tested in turbulence representative of the high frequency end of the spectrum in a simulated suburban atmospheric boundary layer. Data was measured for the $0^{\circ}$ and $45^{\circ}$ horizontal wind approach directions and vertical attack angles ranging from $-4.5^{\circ}$ to $+4.5^{\circ}$. Analysis of the power spectrum of the fluctuating lift indicated that vertical vortex oscillations could be significant for VMS with a large depth ratio attached to a structure with a low natural frequency. Analysis of the galloping test data indicated that VMS with large depth ratios, greater than about 0.5, and low natural frequency could also be subject to galloping instability.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권5호
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• pp.190-196
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• 2002

In this paper, the response characteristics of CAN-based feedback control system are analyzed when message time delays through the network are considered. The message time delays are composed of computation time delay and communication time delay. The application layer of CAN communication is modeled mathematically to analyze two time delays, and the communication time delay is redefined under several assumption conditions. The CAN-based feedback control system is proposed as a target system that is the machining system with the three axes. The response characteristics of time delays in the proposed system are analyzed through computer simulations, and can be improved by the compensation using the PID tuning method to satisfy the design specifications of the system.

• 한국컴퓨터정보학회논문지
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• 제21권1호
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• pp.79-84
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• 2016

In this paper, we propose reliable message transmission scheme based on CoAP, considering the constrained feature of IoT device, such as low power, the limited memory size and low computing capacity. Recently, the various kinds of application protocol has been studied to support IoT environments. In particular, CoAP protocol was developed as application protocol for IoT at the IETF core WG. However, because CoAP protocol is deigned to be used in constrained node, this protocol uses UDP at transport layer. Thus, data loss may occur frequently in network congestion environments. The proposed scheme, in this paper, is to overcome the problem of frequent data loss with low overhead. Also it includes the function which is to minimize the data loss in sleep mode of IoT device.