• 한국통신학회논문지
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• 제27권11C호
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• pp.1055-1063
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• 2002

본 논문은 여러 개의 다중 메트릭을 이용하여 경로 선택을 수행하는 문제에 대해 연구했다. 현재 인터넷에서의 라우팅은 하나의 메트릭을 이용하여 경로선택을 수행하고 있으며, 하나의 메트릭에 의해 선택된 경로는 하나의 요구사항만을 충족시켜 줄 수 있는 best-effort 서비스이다. 여러 서비스 품질(QoS)을 요구하는 콜에 대해 만족시켜주기 위해서는 경고가 여러 제한에 걸리게 된다. 많은 경우에 경로 선택문제라는 것은 NP-complete이다. 본 논문에서는 지연 메트릭에 기반을 두고 네트워크 자원에 대한 정보에 영향을 받는 비용 메트릭을 이용한 widest-least cost 라우팅 알고리즘을 제안한다. 이 알고리즘은 다중의 메트릭을 이용하는 라우팅 알고리즘으로써 트래픽 분산 능력을 갖고 있어서, 네트워크 링크가 부하가 적을 때는 최소거리 경로를 선택하도록 하는 것이고, 네트워크 부하가 클 경우에는 트래픽 엔지니어링이 수행되어 트래픽을 다른 경로로 이동시키도록 하는 것이 목표이다. 이러한 결과는 다른 알고리즘과의 실험 결과를 통해 비교하였다.

• Journal of Communications and Networks
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• 제14권4호
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• pp.451-460
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• 2012

Natural disasters often lead to regional failures that can cause network nodes and links co-located in a large geographical area to fail. Novel approaches are required to assess the network vulnerability under such regional failures. In this paper, we investigate the vulnerability of networks by considering the geometric properties of regional failures and network nodes. To evaluate the criticality of node locations and determine the critical areas in a network, we propose the concept of ${\alpha}$-critical-distance with a given failure impact ratio ${\alpha}$, and we formulate two optimization problems based on the concept. By analyzing the geometric properties of the problems, we show that although finding critical nodes or links in a pure graph is a NP-complete problem, the problem of finding critical areas has polynomial time complexity. We propose two algorithms to deal with these problems and analyze their time complexities. Using real city-level Internet topology data, we conducted experiments to compute the ${\alpha}$-critical-distances for different networks. The computational results demonstrate the differences in vulnerability of different networks. The results also indicate that the critical area of a network can be estimated by limiting failure centers on the locations of network nodes. Additionally, we find that with the same impact ratio ${\alpha}$, the topologies examined have larger ${\alpha}$-critical-distances when the network performance is measured using the giant component size instead of the other two metrics. Similar results are obtained when the network performance is measured using the average two terminal reliability and the network efficiency, although computation of the former entails less time complexity than that of the latter.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 1997년도 춘계학술대회 발표논문집
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• pp.163-181
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• 1997

This dissertation provides a theroetic study on the network security in general , the firewall in particular . In fact, the firewall has been recognized as a very promising option to obtain the security in the real world network environment . The dissertation provides a thorough theoretic investigation on the various problems raised in the computer network, and also explores a methodology of the security against IP spoofing. Moreover, it investigates a systematic procedure to make analysis plans of the firewall configuration. Based on the above investigation and analysis , this dissertation provides two approaches to network security, which address a number of issues both at the network and at application level. At the network level. a new methdo is proposed which uses packet filtering based on the analysis of the counter plot about the screen router. On the other hand at the application level, a novel method is exlored which employs security software , Firewall-1, on Bastion host. To demonstrate the feasibility and the effectiveness of the proposed methodologes, a prototype implementation is made. The experiment result shows that the screen router employing the proposesed anti-IP spoofing method at the network level is effective enough for the system to remain secure without being invaded by any illegarl packets entering from external hackers. Meanwhile , at the application level. the proposed software approach employing Firewall -1 is proved to be robust enough to provent hackings from the outer point to point protocol connection. Theoretically, it is not possible to provide complete secuirty to the network system, because the network security involove a number of issues raised from low level network equipments form high level network protocol. The result in this dissertation provides a very promising solution to network security due to its high efficiency of the implementation and superb protectiveness from a variety of hacking.

• 한국산업정보학회논문지
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• 제2권1호
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• pp.103-123
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• 1997

This dissertation provides a theoretic study on the network security in general , the firewall in particular. In fact the firewall has been recognized as a very promising option to obtain the security inthe real work network environment . The dissertation provides a throuth theoretic investigation on the various problems raised in the computer network, and also explores a methodology of the security against IP spoofing. Moreover, it investigates a systematic procddure to make analysis and plans of the firewall configuration . Based on the above investigation and analysis, this dissertation provides two approaches to network security , which address anumber of issuesboth at the network and at applicatino level. At the network level, a new method is proposed which uses packet filtering based on the analysis of the counter plot about the screen router.On the other hand, at the application level, a novel method is explored which employs secureity software. Firewall-1 , on Bastion host. To demonstrate the feasibililty and the effectiveness of the proposed methodologties , a prototype implementation is made The experiment result shows that the screen router employing the proposed anti-IP spoofing method at the network level is effective enough for the system to remain secure without being invaded by any illegal packets entering form external hackers. Meanwhile , at the application level, the proposed software approach employing Firewall-1 is proved to be robust enugh to prevent hackings from the outer point the point protocal connnection . Theoretically, it is not possible to provide complete security to the network system, because the network security involve a number of issues raised form low level network equipments form high level network protocol. The result inthis dissertation provides a very promising solution to network security due to its high efficiency of the implementation and superb protectiveness from a variety of hacking.

• 전기학회논문지
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• 제66권9호
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• pp.1373-1378
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• 2017

This paper presents a basic ECU(Electronic Control Unit) hardware development procedure for the functional safety of in-vehicle network systems. We consider complete hardware redundancy as a safety mechanism for in-vehicle communication network under the assumption of the wired network failure such as disconnection of a CAN bus. An ESC (Electronic Stability Control) system is selected as an item and the required ASIL(Automotive Safety Integrity Level) for this item is assigned by performing the HARA(Hazard Analysis and Risk Assessment). The basic hardware architecture of the ESC system is designed with a microcontroller, passive components, and communication transceivers. The required ASIL for ESC system is shown to be satisfied with the designed safety mechanism by calculation of hardware architecture metrics such as the SPFM(Single Point Fault Metric) and the LFM(Latent Fault Metric).

• 마이크로전자및패키징학회지
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• 제20권4호
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• pp.75-79
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• 2013

A power distribution network (PDN) is a network that provides connection between the voltage source supply and the power/ground terminals of a microprocessor chip. It consists of a voltage regulator module, a printed circuit board, a package substrate, a microprocessor chip as well as decoupling capacitors. For power integrity analysis, the board and package layouts have to be transformed into an electrical network of resistor, inductor and capacitor components which may be expressed using the S-parameters models. This modeling process generally takes from several hours up to a few days for a complete board or package layout. When the board and package layouts change, they need to be re-extracted and the S-parameters models also need to be re-generated for power integrity assessment. This not only consumes a lot of resources such as time and manpower, the task of PDN modeling is also tedious and mundane. In this paper, a block-based PDN modeling is proposed. Here, the board or package layout is partitioned into sub-blocks and each of them is modeled independently. In the event of a change in power rails routing, only the affected sub-blocks will be reextracted and re-modeled. Simulation results show that the proposed block-based PDN modeling not only can save at least 75% of processing time but it can, at the same time, keep the modeling accuracy on par with the traditional PDN modeling methodology.

• 한국전자통신학회논문지
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• 제7권6호
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• pp.1471-1477
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• 2012

소셜네트워크는 다양한 콘텐츠와의 결합을 통하여 네트워크를 통해 형성된 지인 관계를 기반으로 공유와 배포를 원활하게 하는 주요 플랫폼으로 활용되는 등 몇 가지의 공통적인 기능을 가지고 있다. 이에 트위터, 페이스북, 카카오스토리를 모두 사용하고 있는 사용자들을 대상으로 설문조사를 진행하였으며, 설문에 응답한 자료를 통계 내어 각각의 서비스가 영향을 주는 요인들은 어떤 것인지 완성적 사회자본과 도구적 사회자본으로 나누어 분석한 결과를 제시하였다. 이 연구는 사용자들의 목적에 따라 소셜네트워크를 선택하는 기준이 되고, 새로운 소셜네트워크를 개발하거나 기존의 서비스를 발전시키는데 기여할 수 있을 것이다.

• Journal of information and communication convergence engineering
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• 제16권2호
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• pp.84-92
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• 2018

For large wireless sensor networks running on battery power, the time synchronization of all sensor nodes is becoming a crucial task for waking up sensor nodes with exact timing and controlling transmission and reception timing. However, as network size increases, this synchronization process tends to require long processing time consume significant power. Furthermore, a naïve synchronization scheduler may leave some nodes unsynchronized. This paper proposes a power-efficient scheduling algorithm for time synchronization utilizing the notion of density, which is defined by the number of neighboring nodes within wireless range. The proposed scheduling algorithm elects a sequence of minimal reference nodes that can complete the synchronization with the smallest possible number of hops and lowest possible power consumption. Additionally, it ensures coverage of all sensor nodes utilizing a two-pass synchronization scheduling process. We implemented the proposed synchronization algorithm in a network simulator. Extensive simulation results demonstrate that the proposed algorithm can reduce the power consumption required for the periodic synchronization process by up to 40% for large sensor networks compared to a simplistic multi-hop synchronization method.

• International Journal of Computer Science & Network Security
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• 제22권10호
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• pp.171-176
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• 2022

A dramatic rise in the number of people dying from heart disease has prompted efforts to find a way to identify it sooner using efficient approaches. A variety of variables contribute to the condition and even hereditary factors. The current estimate approaches use an automated diagnostic system that fails to attain a high level of accuracy because it includes irrelevant dataset information. This paper presents an effective neural network with convolutional layers for classifying clinical data that is highly class-imbalanced. Traditional approaches rely on massive amounts of data rather than precise predictions. Data must be picked carefully in order to achieve an earlier prediction process. It's a setback for analysis if the data obtained is just partially complete. However, feature extraction is a major challenge in classification and prediction since increased data increases the training time of traditional machine learning classifiers. The work integrates the CNN-MDRP classifier (convolutional neural network (CNN)-based efficient multimodal disease risk prediction with TANFIS (tuned adaptive neuro-fuzzy inference system) for earlier accurate prediction. Perform data cleaning by transforming partial data to informative data from the dataset in this project. The recommended TANFIS tuning parameters are then improved using a Laplace Gaussian mutation-based grasshopper and moth flame optimization approach (LGM²G). The proposed approach yields a prediction accuracy of 98.40 percent when compared to current algorithms.

• Management Science and Financial Engineering
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• 제5권2호
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• pp.55-59
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• 1999

In this note, we introduce the Fire Sequencing Problem, which arises in military operations. Given m weapons, n fixed targets nad required duration of firing of the weapons on the targets, we want to determine the start time of firing on each target so that makespan is miniized while satisfying various operational constraints. We show that the decision problem of the Fire Sequencing problem is strongly NP-complete and remains strongly NP-complete even if the number of weapons is two. We also briefly discuss the results with respect to the complexities of several well-known scheduling models.