• Journal of the Institute of Convergence Signal Processing
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• v.12 no.1
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• pp.38-43
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• 2011

Cluster-based routing is high energy consumption of cluster head nodes. A recent approach to resolving the problem is the dynamic cluster technique that periodically re-selects cluster head nodes to distribute energy consumption of the sensor nodes. However, the dynamic clustering technique has a problem that repetitive construction of clustering consumes the more energies. This paper proposes a solution to the problems described above from the energy efficiency perspective. The round-robin cluster header(RRCH) technique, which fixes the initially structured cluster and sequentially selects cluster head nodes, is suggested for solving the energy consumption problem regarding repetitive cluster construction. A simulation result were compared with the performances of two of the most widely used conventional techniques, the LEACH(Low Energy Adaptive Clustering Hierarchy) and HEED(Hybrid, Energy Efficient, Distributed Clustering) algorithms, based on energy consumption, remaining energy for each node and uniform distribution. The evaluation confirmed that in terms of energy consumption, the technique proposed in this paper was 26.5% and 20% more efficient than LEACH and HEED, respectively.

• Journal of the Korea Computer Industry Society
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• v.3 no.1
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• pp.85-94
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• 2002

EMRCA(Explicit Max_min Rate Control Algorithm) switch, which has been proposed in the ATM(Asychronous Transfer Mode) standard, controls the ABR(Available Bit Rate) service traffic in the ATM networks. The ABR service class of ATM networks uses a feedback control mechanism to adapt to varying link capacities. The VS/VD(Virtual Source/Virtual Destination) technique offers the possibility to segment the otherwise end-to-end ABR control loop into separate loops. The improved feedback delay and the control of ABR traffic inside closed segments provide a better performance and QoS(Quality of Service) for ABR connections with respect to throughput, delay, and jitter. This paper is study of an ABR VS/VD flow control method. Linear control theory offers the means to derive correct choices of parameters and to assess performance issues, like stability of the system, during the design phase. The performance goals are a high link utilization, fair bandwidth distribution and robust operation in various environments, which are verified by discrete event simulations. The major contribution of this work is the use of linear control theory to model and design an ABR flow control method tailored for the special layout of a VS/VD switch, the simulation shows that this techniques better than conventional method.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.312-312
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• 2019

지구온난화로 인하여 기상학적 변동성 증가 및 수질, 수자원, 생태계 등의 다양한 영역에 영향을 야기하고 있으며, 이를 통한 피해가 전 세계적으로 증가하고 있는 추세이다. 이에 본 연구에서는 최근 다양한 분야에서 수문학적 빈도에 영향을 미친다고 알려진 AO(Arctic Oscillation), NAO(North Atlantic Oscillation), ENSO(El $Ni{\tilde{n}}o$-Southern Oscillation), PDO(Pacific Decadal Oscillation), MJO(Madden-Julian Oscillation)등의 외부인자중 SST, MJO를 활용하여 계절단위의 수문량 정도에서 기상학적 변량과 관측유역 강수량의 관계를 정립하고 발생 가능한 24시간 지속시간 극치강수량을 모의하였다. 이를 위하여 Bayesian 통계기법을 이용한 비정상성 빈도해석모형을 근간으로 외부 기상인자에 의한 계절강수량 예측모형인 계층적 베이지안 네트워크(Hierarchical Bayesian Network, HBN)를 구축한 후 산정된 결과를 입력 자료로 하여 직접적으로 일단위 이하의 극치강수량을 상세화 시킬 수 있는 베타 모델(four parameter beta, 4PB)을 연계한 계층적 베이지안 네트워크 베타모델(Hierarchical Bayesian Network-4beta Model, HBN4BM)을 개발하여 기상변동성을 고려한 상세화 모형을 개발하였다. 여름강수량 산정 결과 한강 유역의 경우 2016년은 관측값 573.85mm, 모의 값 567.15mm를 나타내어 약 1.2%의 오차를 나타냈으며, 2017년 및 2018년은 4.5%, 6.8%의 오차에서 모의가 이루어졌다. 금강의 경우 2016년은 다른 연도에 비하여 35.2%라는 큰 오차를 보였지만 불확실성 구간에서 모의가 이루어 졌으며, 2017년 및 2018년은 0.3%, 2.1%의 작은 오차가 발생하였다. 24시간 모의 결과는 최소 0.7%에서 최대 27.1%의 오차를 나타냈으며, 평균적으로 16.4%의 오차 결과가 모의되어 모형의 신뢰성을 확인하였다.

• KIPS Transactions on Software and Data Engineering
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• v.7 no.11
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• pp.419-426
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• 2018

Due to the FMD(foot-and-mouth disease), the domestic animal husbandry and related industries suffer enormous damage every year. Although various academic researches related to FMD are ongoing, engineering studies on the social effects of FMD are very limited. In this study, we propose a systematic methodology to analyze emotional responses of regular citizens on FMD using text mining techniques. The proposed system first collects data related to FMD from the tweets posted on Twitter, and then performs a polarity classification process using a deep-learning technique. Second, keywords are extracted from the tweet using LDA, which is one of the typical techniques of topic modeling, and a keyword network is constructed from the extracted keywords. Finally, we analyze the various social effects of regular citizens on FMD through keyword network. As a case study, we performed the emotional analysis experiment of regular citizens about FMD from July 2010 to December 2011 in Korea.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.121-126
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• 2018

IEEE 802.1 TSN TG is developing standards for end-to-end delay bounds and zero packet loss based on Ethernet technology. We focus on packet forwarding techniques. TSN packet forwarding techniques can be classified into Synchronous and Asynchronous framework. Synchronous approach allocates fixed time period for a class, yet is complex for large networks. Asynchronous approach provides delay guarantee by regulator-scheduler pair, yet is unnecessarily complex, too. We propose network components for TSN Asynchronous architecture, which remove the complexity of maintaining flow state for regulation decisions. Despite such a simplicity, the proposed architecture satisfies the TSN's delay requirements provided the limited high priority traffic's maximum packet length.

• Journal of the Korea Society of Computer and Information
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• v.26 no.4
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• pp.63-74
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• 2021

Location-based services (LBSs) are expected to process a large number of spatial queries, such as shortest path and k-nearest neighbor queries that arrive simultaneously at peak periods. Deploying more LBS servers to process these simultaneous spatial queries is a potential solution. However, this significantly increases service operating costs. Recently, batch processing solutions have been proposed to process a set of queries using shareable computation. In this study, we investigate the problem of batch processing moving k-nearest neighbor (MkNN) queries in dynamic spatial networks, where the travel time of each road segment changes frequently based on the traffic conditions. LBS servers based on one-query-at-a-time processing often fail to process simultaneous MkNN queries because of the significant number of redundant computations. We aim to improve the efficiency algorithmically by processing MkNN queries in batches and reusing sharable computations. Extensive evaluation using real-world roadmaps shows the superiority of our solution compared with state-of-the-art methods.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.3
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• pp.525-536
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• 2012

This paper proposes methods of securing Smart Grid system against various types of cyber threats by separating AMI networks from the public network, the Internet, and providing an AMI specific authentication framework. Due to the fact that thousands and millions of AMI devices to be deployed would be directly or indirectly connected to the public network without any authentication procedures for access control, currently being developed AMI architectures could be widely exposed to considerable number of penetrating attacks. Furthermore, there have not been a sufficient number of researches on authentication frameworks with basis on the specific circumstances of AMI networking that should support varied authentication protocols among security associations and AMI linking devices. This work makes a proposal of isolating smart meters from HAN devices and the Internet and integrating network/application level authentication frameworks with an EAP-based authentication architecture. These approaches are beneficial to deploy AMI with security and efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4D
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• pp.433-442
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• 2010

Recent decrease in the availability of experienced skilled labor and a corresponding lack of new entrants has required the need for automating many of the construction equipment used in the construction industry. In particular, excavators are widely used throughout earthwork operations and automating its tasks enables work to be performed with higher productivity and safety. This paper introduces an optimal path generation method which is one of the core technologies required to make "Intelligent" excavators a reality. The method divides a given earthwork area into unit cells, identifies networks created by linking these cells, and identifies the optimal path an excavator should follow to minimize its total transportation costs. In addition, the method also accounts for drainage direction and path continuity to ensure that the generated path considers site specific conditions.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.135-136
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• 2023

This study is an empirical result for building an onboard communication network using metal surface wave communication and is a consideration of its application within the ship. Over the past three years, the applicability and the performance of metal surface wave communication has been confirmed by testing on five small and medium ships. In the tests, IEEE 802.11 protocol of Wi-Fi was used, and the signals were generated in the form of surface waves. Data was sent from AP to AP in the point-to-point form, and the transmission speed was measured at the same time. If necessary, additional repeaters were used to extend the transmission distance. As derived a transmission speed of 5 to 100 Mbps in wireless communication restricted areas of the 5 ships, it is believed that it is possible to reduce the weight of ships and costs by eliminating the communication cables by using surface wave communication as the back-bone network on ships.

• Journal of the Korean Institute of Landscape Architecture
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• v.52 no.1
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• pp.59-70
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• 2024

As urbanization progresses, the demand for parks and green space is increasing. Park green spaces in the city are important spaces in the city because they are recognized as spaces where people can freely engage in outdoor activities. The park service area is a measure that shows the extent to which services are provided based on distance. In this process, the concept of accessibility plays an important role, and walking, in particular, as the most basic means of transportation for people and has a great influence on the use of parks. However, the current park service area analysis focuses on discovering underprivileged areas, so detailed evaluation of beneficiary areas is insufficient. This study seeks to evaluate park service areas based on the pedestrian accessibility and the pedestrian network. Park services are services that occur when users directly visit the park, and accessibility is expected to be reflected in terms of usability. To quantify the pedestrian network, this study used space syntax to analyze pedestrian accessibility based on integration values. The integration values are an indicators that quantify the level of accessibility of the pedestrian network, and in this study, the higher the integration value, the higher the possibility of park use. The results of the study are as follows. First, Bundang-gu's park service area accounts for 43%, and includes most sections with high pedestrian accessibility, but some sections with good pedestrian accessibility are excluded. This can be seen as a phenomenon that occurs when residential areas and commercial and business areas are given priority during the urban planning process, and then park and green areas are selected. Second, based on Bundang-gu, the park service area and pedestrian accessibility within the park service area were classified by neighborhood unit. Differences appear for each individual neighborhood unit, and it is expected that the availability of the park will vary accordingly. In addition, even in areas created during the same urban planning process, there were differences in the evaluation of park service areas according to pedestrian accessibility. Using this, it is possible to evaluate individual neighborhood units that can be reflected in living area plans, and it can be used as a useful indicator in park and green space policies that reflect this in the future.