• 한국항행학회논문지
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• 제12권6호
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• pp.627-633
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• 2008

MANET(mobile adhoc networks)기반 통신 프로토콜은 고속으로 이동하는 VANET(vehicular adhoc networks)환경에서 차량 상호간의 메시지 전송과 긴급메시지 전송이 불가능 할 수 있다. 메시지 전송의 신뢰성을 보장하기 위해 본 논문에서는 특정 구간에서 교통사고 및 구간정체로 인한 통신의 포화상태 발생과 긴급통신 중 히든노드 개입으로 인한 데이터 충돌과 전송지연을 해결하기 위해 방향성 안테나 기반 은닉노드 방지 기법을 제안한다. 제안하는 프로토콜은 메시지의 신뢰성 있는 전송을 위해 양방향성 안테나를 이용하여 노드 간 간섭과 제어 메시지 전송 지연을 최소화 한다. 시뮬레이션을 통해 메시지의 신뢰성 있는 전달 및 메시지 간 충돌을 줄일 수 있음을 보이고, 결론에서는 연구 내용 및 우수성을 나타내었다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2011년도 추계학술발표대회
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• pp.1079-1081
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• 2011

컨테이너터미널 장치장 내 교차로에서 무인 YT(Yard Tractor)간 충돌방지를 위하여 RFID(Radio Frequency Identification) 태그와 ad-hoc 네트워크를 이용한 교차로 충돌방지 알고리즘을 제안한다. 또한 ad-hoc 네트워크 라우팅 프로토콜은 장치장 교차로에서 충돌방지를 위한 YT 간 통신성능을 결정하는 중요한 요소로써, 장치장 교차로 환경과 YT의 이동성을 고려하여 프로토콜을 결정해야 한다. 따라서 RFID 태그를 이용한 YT 위치정보와 AODV(Ad hoc On demand Distance Vector) 방식의 Hello 메시지를 이용해서 충돌방지를 위한 ad-hoc 네트워크 라우팅 프로토콜을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권3호
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• pp.1031-1046
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• 2018

Vehicular ad hoc network (VANET) is a dedicated network to connect vehicles without any centralized administration or infrastructure. The wireless access in vehicular environments (WAVE) protocol leveraging IEEE 1609/802.11p is widely implemented for VANETs. However, in congested traffic situation, the performance of the WAVE system degrades significantly due to serious collision, especially for safety related broadcast services on the control channel (CCH) interval due to the inherent drawback of its collision avoidance mechanisms called carrier sense multiple access with collision avoidance (CSMA/CA). In this paper, we propose a method that can decrease the number of frame collisions in CCH with a few modifications to the IEEE 802.11p protocol. In the paper, vehicles still employ CSMA/CA to compete for the channel access opportunity. However, by taking advantage of periodicity of synchronization interval, a two-state switching scheme introducing two new inter frame space (IFS) is proposed to reduce the number of competing vehicles substantially and as a result, the collision probability is significantly decreased. The simulation results demonstrate the superiority of the proposed method in packet collision rate.

• 한국IT서비스학회지
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• 제11권4호
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• pp.195-213
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• 2012

In ubiquitous environments, the Intelligent Transportation System (ITS) protocol is a typical service used to improve the quality of life for humans. The Vehicular Ad-hoc Network (VANET) protocol, a part of ITS, needs further study with regards to its support for high reliability, high speed mobility, data transmission efficiency, and so on. The IEEE 802.11 standard provides a high data rate channel, but it was designed for peer-to-peer network protocols. IEEE 802.11p also provides a high data rate channel, however, it only facilitates communication between roadside and on-board equipment. A VANET has characteristics that enable its topology to change rapidly; it can also be expanded to a multi-hop range network during communication. Therefore, the VANET protocol needs a way to infer the current topology information relating to VANET equipped vehicles. In this paper, we present the Multi-Beacon MAC Protocol, and propose a method to resolve the problem of beacon collisions in VANET through the use of this Multi-Beacon MAC protocol. Evaluation of the performance of Multi-Beacon MAC protocol by means of both mathematical analyses and simulation experiments indicate that the proposed method can effectively reduce beacon collisions and improve the throughput and the delay between vehicles in VANET systems.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2015년도 하계학술대회
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• pp.13-16
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• 2015

In any mobile ad hoc environment, collision amongst mobile objects is always likely to occur unless there is a certain level of intelligence to detect and avoid the collision. This phenomenon of detection and avoidance is the key attribute for safety applications in vehicle to pedestrian (V2P) communications systems. In this paper, we propose a V2P communications concept for collision detection and avoidance.

• 한국통신학회논문지
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• 제32권7B호
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• pp.463-471
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• 2007

Ad hoc 무선망의 동적인 특성으로 인하여 히든노드 문제가 나타날 수 있기 때문에 ad hoc 무선망에서는 분산방식으로 네트워크가 동작되어야 한다. Ad hoc 무선망에서 CSMA/CA는 비동기적 데이터 트래픽을 위해 가장 많이 사용되는 MAC Protocol 중의 하나이다. 그러나 CSMA/CA는 멀티미디어 데이터의 특성을 보장하지 못한다. 또한 경쟁형(Contention)이므로 채널을 먼저 잡은 하나의 스테이션이 채널을 독점해서 사용하여 채널 기아(starvation)로 인한 공평성문제(fairness problem)가 발생한다. 본 논문에서는 무선 ad hoc망에서 멀티미디어 데이터의 특성을 고려하여, QoS 보장을 위한 MAC protocol을 제안한다.

• 셀메드
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• 제13권14호
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• pp.14.1-14.9
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• 2023

Administration of Scopolamine can be considered a psychopharmacological model of Alzheimer's disease (AD). We made an animal model of Alzheimer's disease (AD) by administering Scopolamine to Blab/c mice. In this study, we investigated the effects of Resplex Alpha on memory impairment and cognitive function in mice in a mouse animal model of Scopolamine-induced memory impairment. Through Y-mazed and passive avoidance behavioral assays, we observed that Resplex Alpha recovered Scopolamine-induced short-term memory and cognitive functions. The results of our study imply that Resplex Alpha may be beneficial in the prevention of Alzheimer's disease (AD).

• 대한본초학회지
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• 제34권3호
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• pp.1-7
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• 2019

Objectives : Amyloid ${\beta}(A{\beta})$ could induce cognitive deficits through oxidative stress, inflammation, and neuron death in Alzheimer's disease (AD). This study was investigated the effect of Angelica keiskei KOIDZUMI (AK) on memory in $A{\beta}$-induced an AD model. Methods : AK was extracted uses 70% ethanol solvent. Total polyphenol and flavonoids content were obtained by the Folin-Ciocalteu and the Ethylene glycol colorimetric methods, respectively. The antioxidant activities were assessed through free radical scavenging assays using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazolin-6-sulfonic acid) (ABTS) methods. Intracerebroventrical (i.c.v) injection of $A{\beta}$ 1-42 was used to induce AD in male ICR mice, followed by administrations of 5, 10 or 20 mg/kg AK on a daily. Animals were subjected to short and long term memory behavior in Y-maze and passive avoidance test. Results : The total polyphenol and flavonoids contents of the AK extract were $88.73{\pm}6.36mg$ gallic acid equivalent/g, $84.21{\pm}5.04mg$ rutin equivalent/g, respectively. The assays of DPPH and ABTS revealed that AK extract in treated concentrations (31.25, 62.5, 125, 250, 500, $1000{\mu}g/m{\ell}$) increased antioxidant activity in a dose-dependent manner. Oral administration of AK extract significantly reversed the $A{\beta}$ 1-42-induced decreasing of the spontaneous alternation in the Y-maze test and $A{\beta}$ 1-42-induced shorting of the step-through latency in the passive avoidance test. Conclusions : The findings suggest that AK indicated the antioxidant protective effects against $A{\beta}$-induced memory deficits, and therefore a potential lead natural therapeutic drug or agent for AD.

• Food Science and Biotechnology
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• 제17권2호
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• pp.384-388
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• 2008

Alzheimer's disease (AD) is the most common neurodegenerative disorder and is responsible for more than 50% of all dementia cases. There is significant interest in finding new sources of compounds that inhibit acetylcholinesterase (AChE) to be used in the treatment of AD, since only a few AChE inhibitors, such as galanthamine, physostigmine, and tacrine, are available for clinical use. In the present study, ICR mice were treated with a 1 mg/kg scopolamine, which caused impaired cognitive ability. The steady consumption of a water extract of Chrysanthemum indicum Linne flowers for 3 months significantly prevented the scopolamine induced deficit of the spatial cognitive capability of mice. It also improved long-term memory in mice with amnesia induced by scopolamine, as assessed by the Morris water maze and passive avoidance tests. In addition, water extract consumption significantly decreased AChE activity in mouse brain, leading to inhibition of acetylcholine hydrolysis.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.300-302
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• 2022

본 논문은 FANET 환경에서 UAV 간에 자원 충돌 없이 무선 자원을 공유 할 수 있는 시분할 다중접속 기반 자원 충돌 회피 기법을 제안한다. 제안하는 기법은 UAV에 설치된 GPS 장치로부터 얻은 정보 토대로 UAV 이동성을 추측하여 자원 충돌 발생률을 감소시키고자 한다. 시뮬레이션을 통해 경쟁기반 방식 프로토콜과 성능 비교를 하였으며, 제안한 알고리즘이 자원 충돌을 감소시킬 수 있음을 확인하였다.