• 한국군사과학기술학회지
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• 제16권1호
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• pp.56-64
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• 2013

TICN, a next-generation tactical communication network based on a wireless network, acts as the backbone of the whole network. TICN requires the routing which takes both survivability of passage, reliability, and safety of wireless link into consideration. A tactical network like TICN may maintain the passage for just a short period of time due to topology's frequent changes; In this process all nodes, dependent on batteries for their necessary energy, are restricted by batteries' durability in due course. To overcome this shortcoming, the up-to-date protocols consider only either of diminishing or balancing out energy consumptions. Thus there was a limitation to enhancing both throughput and energy efficiency. The thesis proposes a protocol which regards both throughput and energy efficiency, and enhances node survivability by means of minimizing and balancing energy consumption of the whole network. The protocol brings out an improvement in throughput and makes each node's energy usage more effective.

• 한국정보통신학회논문지
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• 제19권7호
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• pp.1561-1567
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• 2015

모바일 애드혹 네트워크의 노드는 일반적으로 에너지의 용량이 제한된 배터리를 사용한다. 경로의 안정성을 유지하기 위해 균형 잡힌 에너지 소비가 중요하다. 본 논문에서는 애드혹 네트워크에서 데이터 전송 경로의 안정성을 향상시키는 것을 목표로 한다. 이를 위해 데이터를 전송할 수 있는 최단 전송 경로 중에서 노드 에너지 잔량의 최소값이 가장 큰 경로를 선택하는 새로운 라우팅 프로토콜을 제안한다. 에너지 잔량의 최소값이 가장 큰 경로는 다른 경로보다 상대적으로 긴 수명을 갖게 되어 데이터 전송에 안정성을 향상 시킬 수 있다. NS-3 시뮬레이터를 사용하여 제안하는 라우팅 프로토콜이 AODV와 EA-AODV보다 수명이 긴 안정적인 경로를 제공하는 것을 확인한다.

• 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.

• International Journal of Computer Science & Network Security
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• 제22권11호
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• pp.241-247
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• 2022

Ad hoc network is self-organized network powered by battery. The reliability of virtual user identification and channel security are reduced when SNR is low due to limited user energy. In order to solve this problem, a joint virtual user identification and channel security en/decoding method is proposed in this paper. Transmitter-receiver-based virtual user identification code is generated by executing XOR operation between orthogonal address code of transmitter and pseudo random address code of receiver and encrypted by channel security code to acquire orthogonal random security sequence so as to improve channel security. In order to spread spectrum as well as improve transmission efficiency, data packet is divided into 6-bit symbols, each symbol is mapped with an orthogonal random security sequence. Subspace-based method is adopted by receiver to process received signal firstly, and then a judgment model is established to identify virtual users according to the previous processing results. Simulation results indicate that the proposed method obtains 1.6dB E_b/N₀ gains compared with reference methods when miss alarm rate reaches 10^-3.

• 한국통신학회논문지
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• 제42권2호
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• pp.383-385
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• 2017

For the purpose of providing high data rate real-time services, radio transmission technologies for ship ad-hoc network based on the Recommendation ITU-R 1842-1 are designed. In order to increase the link throughput of real-time services, in this paper, we investigate the performance of the SANET with the spatial transmit diversity techniques are employed. Based on the analysis of the packet error rate and throughput, we select the efficient multiple antenna schemes for SANET to improve the link reliability.

• 대한한의학회지
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• 제23권4호
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• pp.15-26
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• 2002

There is much confusion in the field of atopic dermatitis (AD) regarding how to best measuredisease severity objectively. Therefore, we aimed to establish a new adequate scoring system for AD, that should be based on comparisonand analysis of various scoring systems. We report as follows. Methods: We searched for data relating to severity scoring systems for atopic dermatitis in Entrez PubMed From 1990 to 2001 Results and Conclusions: 1. Properties of severity scoring systems were validity, reliability, sensitivity of change and ease of use. 2. The essential items of severity scoring systems were extent. intensity and subjective symptoms. 3. The surface extent of the lesion was evaluated by the percentage of involvement of each of 10 areas. 4. The criteria of severity were divided into intensity and subjective symptoms. Intensity items are erythema, papulation, lichenification, oozing, dryness, excoriations, and pigmentation. The subjective symptom is pruritus, evaluated according to sleep loss. 5. The significant items of severity scoring system were symptomsrather than areas. As it were, we assumed extent accounted for around 30% of each total score, with intensity and subjective symptoms representing 70%.

• 아동학회지
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• 제27권3호
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• pp.29-51
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• 2006

The 191 subjects of this study were counselors working with children under 18 years of age. The instrument was validated in an antecedent study and used after testing for reliability. Data were analyzed by Cronbach' a, quantification methods I, and multi-regression analysis. Results showed demographic variables at 5% of ad-$R^2$ over total burnout. Hobbies, counseling career, religion, and major field of study were significant. Marital status and caseload affected 'doubt about job.' Counseling field, qualifications and academic career affected 'negative personal relationship' and 'symptoms of somatization.' Psychological variables were 48% of ad-$R^2$ over total burnout. Self-esteem, type AB, self-insight and empathy ability for countertransference management ability were significant. Lower self-esteem, stronger type A personality, higher self-insight and lower empathy ability, produced higher degree of burnout.

• Journal of Communications and Networks
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• 제15권2호
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• pp.153-163
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• 2013

In recent years, more and more researches have been focusing on trust management of vehicle ad-hoc networks (VANETs) for improving the safety of vehicles. However, in these researches, little attention has been paid to the location privacy due to the natural conflict between trust and anonymity, which is the basic protection of privacy. Although traffic safety remains the most crucial issue in VANETs, location privacy can be just as important for drivers, and neither can be ignored. In this paper, we propose a beacon-based trust management system, called BTM, that aims to thwart internal attackers from sending false messages in privacy-enhanced VANETs. To evaluate the reliability and performance of the proposed system, we conducted a set of simulations under alteration attacks, bogus message attacks, and message suppression attacks. The simulation results show that the proposed system is highly resilient to adversarial attacks, whether it is under a fixed silent period or random silent period location privacy-enhancement scheme.

• 대한임베디드공학회논문지
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• 제14권4호
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• pp.219-226
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• 2019

One of the most widely studied protocols for tactical ad-hoc networks is Optimized Link State Routing Protocol (OLSR). As for OLSR research, most research work focus on reducing control traffic overhead and choosing relay point. In addition, because OLSR is mostly dependent on link detection and propagation, dynamic Hello timer become research challenges. However, different timer interval causes imbalance of link validity time by affecting link lifetime. To solve this problem, we propose a weighted topology graph model for constructing a robust network topology based on the link validity time. In order to calculate the link validity time, we use control message timer, which is set for each node. The simulation results show that the proposed mechanism is able to achieve high end-to-end reliability and low end-to-end delay in small networks.

• 전자공학회논문지CI
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• 제45권6호
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• pp.68-76
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• 2008

모바일 애드 혹 네트워크(MANET)는 네트워크 토폴로지의 변화로 인해 데이터 전송의 정지확률과 경로가 끊어질 확률이 높아 경로 유지가 힘들다. 이러한 MANET의 특성 때문에 안정적인 데이터 전송률을 보장하기 어렵다. 따라서 노드 간 링크의 데이터 전송률에 대한 신뢰도를 평가하고, 이에 기반을 둔 라우팅 알고리즘이 필요하다. 이에 본 논문에서는 링크 신뢰도 기반 라우팅을 다음과 같이 제안한다. 먼저 과거 정보를 사용하여 가설을 추론하는 베이지안 추론을 적용하여 노드 간 링크의 신뢰도를 측정 할 수 있는 링크 신뢰도 측정 모델을 제안한다. 또한, 노드의 흡수와 노드 간의 연결성을 고려한 기존의 OLSR 프로토콜에 추가적으로 링크 신뢰도 측정 모델을 적용한 링크 신뢰도 기반 OLSR 프로토콜을 제안한다. NS-2를 사용한 시뮬레이션 결과는 링크 신뢰도 측정 모델을 적용한 OLSR 프로토콜이 기존의 OLSR 프로토콜에 비해 전송 성공률과 안정성 측면에서 성능이 우수함을 보여준다.