• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권6호
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• pp.1113-1132
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• 2011

In wireless sensor networks (WSNs), most energy saving asynchronous MAC protocols are custom tailored for unicast communications only. However, broadcast protocols are very commonly used in WSNs for a variety of functionalities, such as gathering network topology information, event monitoring and query processing. In this paper, we propose a novel low-power asynchronous broadcast MAC protocol called Alarm Broadcast (A-CAST). A-CAST employs the strobe preamble that specifies the residual waiting time for the following data transmission. Each receiver goes back to sleep upon hearing the strobe preamble for the residual time duration, to conserve energy and to wake up just before data transmission starts. We compute the energy consumption of A-CAST via rigorous mathematical analysis. The analytic results show that A-CAST outperforms B-CAST, a simple broadcast extension of the well-known B-MAC. We also implement A-CAST on sensor motes and evaluated its performance through real experiments. Our experimental results show that A-CAST reduces the energy consumption by up to 222% compared to the previously proposed protocols.

• 융합신호처리학회논문지
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• 제12권2호
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• pp.119-127
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• 2011

The paper surveys various analytical models for IEEE 802.11 medium access control protocols and critically discusses recent issues developing in wireless mobile ad hoc networks and their MACs. The surveyed MAC protocols include the standard IEEE 802.11 MAC suites such as IEEE 802.11 DCF, IEEE 802.11 PCF, IEEE 802.11e EDCA, and IEEE 802.11 ad hoc mode; and also the newer, de facto MAC protocols. We study the analytic models of the standard MAC suites followed by the newer analytic models that have been published in recent years. Also, the paper tries to include most of current literatures discussing analytic modeling of MAC in conjunction to some critical issues such as contention among ad hoc nodes, hidden terminal problems, and real-time service support.

• 한국통신학회논문지
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• 제42권4호
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• pp.871-878
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• 2017

사물 인터넷에 대한 관심이 증가되고 사물인터넷 시장 규모가 증가함에 따라 사물인터넷 관련 기기와 프로토콜이 발전하고 있다. 상호 운용성에 대한 문제가 발생됨에 따라 사물인터넷 디바이스뿐만 아니라 시스템 사업자와 서비스 및 애플리케이션 시장과 사물인터넷 표준 정립은 혼란을 겪게 됐고, 사물과 사물 간의 통신은 서로 다른 플랫폼에 의해 방해되고 있다. 현재 다양한 사물인터넷 플랫폼 개발과 이기종 플랫폼과의 상호 운용성을 위한 연구가 진행되고 있지만, 여전히 각각의 플랫폼에서 사용되는 프로토콜은 제한적이며 일반화된 구조로 설계되어 있지 않다. 본 논문에서는 사물인터넷 시장에서 대표적으로 사용되는 HTTP, CoAP, MQTT 프로토콜을 분석하여 프로토콜을 선택적으로 사용하는 서비스와 플랫폼 사용의 일반화를 위해 RESTful API를 적용한 자원을 설계하고, 수집된 데이터의 빠른 처리와 안전성을 위한 Database 모델링 과정을 진행하여 사물인터넷 데이터 수집 플랫폼을 구현했다. 이러한 과정을 통해 서로 다른 프로토콜로 통신하는 디바이스들이 한 플랫폼에서 연동되며, 다양한 프로토콜을 적용할 수 있는 일반화된 선택적 프로토콜 기반의 사물인터넷 데이터 수집 플랫폼을 제안한다.

• 대한핵의학회지
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• 제39권2호
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• pp.82-86
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• 2005

In myocardial perfusion scintigraphy, the results of this evalution now confront the practitioner of nuclear medicing with methodologic options. Most nuclear cardiologic studies are performed using thallium-201, Tc-99m sestamibi and Tc-99m tetrofosmin. Some part of these studies use some form of pharmacologic stress test. While tailoring each test to the individual is ideal, this may be impractical for a busy department. Accordingly, established protocols to be used for patients with similar clinical presentations will be helpful. The following review presents methodology of various imaging protocols mainly according to the guidelines of nuclear cardiology procedures in American Society of Nuclear Cardiology.

• 정보보호학회논문지
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• 제15권5호
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• pp.105-114
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• 2005

There are several goals or properties which authentication protocols may have; some of them are key freshness, far-end aliveness, key confirmation, etc. Most of them have extensively been discussed and studied so far in the literature. 'Responsibility' and 'credit', which were first raised by Abadi as additional goals, received quite an exceptional treatment; there were little response from researchers about these new goals. It is surprising to see that these two properties have slipped through any investigation, successfully achieving the positions as the goals for authentication protocols. In this paper, we investigate these two new properties and their relations to authentication protocols, and answers to the question: what brings us credit and responsibility.

• 정보보호학회논문지
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• 제23권1호
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• pp.3-10
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• 2013

많은 인증 키 합의 프로토콜이 제안되어 왔다. 여전히 안전한 인증키 합의 프로토콜을 설계하는 것이 이슈화되고 있다. 이 논문에서는, 전형적인 ID 기반의 암호화 시스템의 공개키와 개인키 뿐 아니라 하나 더 많은 공개키와 개인키를 사용하는 원 라운드 인증 그룹키 합의 프로토콜을 제안한다. 제안된 프로토콜은 Shi et al. 프로토콜과 He et al. 프로토콜을 수정 보완하였다. 제안된 프로토콜의 공개키 개인키와 서명 과정은 그들의 프로토콜보다 단순하다. 제안한 프로토콜은 안전하며, 통신과 계산 비용 면에서 그들의 프로토콜보다 더 효율적이다.

• Journal of Korean Neurosurgical Society
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• 제66권3호
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• pp.308-315
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• 2023

Recent updates in genomic-integrated glioma classification have caused confusion in current clinical practice, as management protocols and health insurance systems are based on evidence from previous diagnostic classifications. The Korean Brain Tumor Society conducted an electronic questionnaire for society members, asking for their ideas on risk group categorization and preferred treatment for each individual diagnosis listed in the new World Health Organization (WHO) classification of gliomas. Additionally, the current off-label drug use (OLDU) protocols for glioma management approved by the Health Insurance Review and Assessment Service (HIRA) in Korea were investigated. A total of 24 responses were collected from 20 major institutes in Korea. A consensus was reached on the dichotomic definition of risk groups for glioma prognosis, using age, performance status, and extent of resection. In selecting management protocols, there was general consistency in decisions according to the WHO grade and the risk group, regardless of the individual diagnosis. As of December 2022, there were 22 OLDU protocols available for the management of gliomas in Korea. The consensus and available options described in this report will be temporarily helpful until there is an accumulation of evidence for effective management under the new classification system for gliomas.

• Journal of Positioning, Navigation, and Timing
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• 제11권1호
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• pp.1-9
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• 2022

Global Navigation Satellite System (GNSS) provides location information using signals from multiple satellites. However, a spoofing attack that forges signals or retransmits delayed signals may cause errors in the location information. To prevent such attacks, authentication protocols considering the navigation message structure of each GNSS can be used. In this paper, we analyze the authentication protocols of Global Positioning System (GPS), Galileo, and BeiDou, and compare the performance of Navigation Message Authentication (NMA) of the above systems, using several performance indicators. According to our analysis, authentication protocols are similar in terms of performing NMA and using Elliptic Curve Digital Signature Algorithm (ECDSA). On the other hand, they are different in several ways, for example, whether to perform Spreading Code Authentication (SCA), whether to use digital certificates and whether to use Timed Efficient Stream Loss-tolerant Authentication (TESLA). According to our quantitative analysis, the authentication protocol of Galileo has the shortest time between authentications and time to first authenticated fix. We also show that the larger the sum of the navigation message bits and authentication bits, the more severely affected are the time between authentications and the time to first authenticated fix.

• 정보보호학회논문지
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• 제18권6B호
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• pp.259-269
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• 2008

Applying Varying Pseudonym (VP) to design of Radio Frequency Identification (RFID) authentication protocol outperforms the other existing approaches in several respects. However, this approach is prone to the well-known denial-ofservice (DOS) attack. In this paper, we examine the de-synchronization problems of VP-based RFID authentication protocols, and propose effective solutions to eliminate such weaknesses. We shall show that the proposed solutions indeed improve the security for these protocols, and moreover, these solutions require 0(1) computational cost for identitying a tag and 0(1) key space on the tag. These excellent performances make them very attractive to many RFID applications.

• 한국멀티미디어학회논문지
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• 제24권8호
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• pp.1068-1075
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• 2021

Wireless sensor network (WSN) can be usefully used in battlefields requiring rapid installation and operation by enabling surveillance and reconnaissance using small sensors in areas where any existing network infrastructure is not formed. As WSN uses battery, energy efficiency acts as a very important issue in network survivability. Layer-based routing protocols have been studied a lot in the aspect of energy efficiency. Many research selected LEACH and PEGASIS protocols as their comparison targets. This study examines the two protocols and LECEEP, a protocol designed by combining their advantages, and proposes a new protocol, A-LECEEP, which is more energy efficient than the others. The proposed protocol can increase energy efficiency compared to the existing ones by eliminating unnecessary transmissions with multiple chains configuration.