• 한국인터넷방송통신학회논문지
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• 제11권1호
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• pp.35-40
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• 2011

본 논문은 센서 네트워크의 각 이벤트 영역에서의 데이터 취합 및 전달을 위한 방법들을 비교 평가한다. 이를 위해 이벤트 영역내의 두 가지 전송 방법인 직접적인 전송 방식과 취합 노드를 통한 전송 방식을 비교한다. 직접적인 전송 방식은 모든 노드가 자신이 측정한 데이터를 전송하기 때문에 데이터의 중복성과 네트워크의 트래픽을 증가시키는 단점을 가진다. 반면에 취합 노드를 통한 전송 방식은 이벤트 영역 내에서 노드들의 데이터를 취합함으로써 데이터의 중복을 방지하고 데이터를 간소화 할 수 있다. 취합 노드의 선정 방식은 노드의 위치에 기반 한다. 즉, 취합 노드가 이벤트 영역의 중앙에 위치한 노드 혹은 싱크 노드와 가장 가까운 노드를 선정하는 것이다. 위 두 가지 방법을 바탕으로 취합 노드 선정 방식들을 모델링 하여 이벤트 영역의 증가에 따른 각 방법의 에너지 소비를 측정한다. 이를 위해, 이벤트 노드와 취합 노드의 거리와 취합 노드와 싱크 노드의 거리를 구하고, 이를 수식으로 간략히 정리한다. 또한, 기존의 에너지 수식을 적용하여 거리 수식과 같이 적용하여 에너지 소비 모델을 만든다. 이를 통해 취합 노드 방식들의 에너지 소비를 비교 평가하여 센서 네트워크에 에너지 효율적인 방식을 찾아낸다.

• 한국통신학회논문지
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• 제35권9B호
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• pp.1295-1304
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• 2010

본 논문에서는 에너지 효율적이고 신뢰성있는 데이터수집을 제공하는 고장감내형 데이터병합을 제안한다. 기존 데이터병합 기법은 패킷 손실에 대응하지 못하거나 대응 하더라도 에너지 소모가 매우 크다. 고장감내형 데이터병합은 적응적 타임아웃 데이터병합 기법에 트랙 토폴로지를 이용한 캐싱 및 재전송 기법을 적용하여 중요 이벤트에 대해 신뢰성있는 데이터수집을 제공한다. 고장감내형 데이터병합은 이벤트 가능성이 없는 평상시에는 기존의 트리 기반의 단일경로 데이터수집을 함으로써 에너지 소모를 줄인다. 하지만 이벤트 가능성이 감지되면 트랙 토폴로지를 이용한 패킷 손실 감지 및 재전송을 통해 데이터병합 결과의 정확도를 높인다. 실험 결과에서 고장감내형 데이터병합은 평균 소모 에너지 측면에서 TAG에 비해 약 8% 에너지 소모가 감소하였고, 이벤트 발생 가능성이 있을 경우 데이터 정확도 측면에서 TAG에 비해 41%정도 우수한 성능을 보였다. 그리고 평균 소모 에너지 측면에서 PERLA에 비해 약 53% 정도 에너지 소모가 감소하였으며, 이벤트 발생 가능성이 있을 경우 데이터 정확도 측면에서는 성능 저하가 거의 없었다.

• Journal of Information Processing Systems
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• 제10권3호
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• pp.412-428
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• 2014

Request oriented sensor networks have stricter requirements than conventional event-driven or periodic report models. Therefore, in this paper we propose a minimum energy data aggregation (MEDA), which meets the requirements for request oriented sensor networks by exploiting a low power real-time scheduler, on-demand time synchronization, variable response frame structure, and adaptive retransmission. In addition we introduce a test bed consisting of a number of MEDA prototypes, which support near real-time bidirectional sensor networks. The experimental results also demonstrate that the MEDA guarantees deterministic aggregation time, enables minimum energy operation, and provides a reliable data aggregation service.

• ETRI Journal
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• 제31권4호
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• pp.463-465
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• 2009

In this letter, we present an event stream processing system that can evaluate a pattern query for a data sequence with predicates. We propose a pattern query language and develop a pattern query processing system. In our system, we propose novel techniques for run-time aggregation and negation processing and apply our system to stream data generated from vehicles to monitor unusual driving patterns.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2010년도 추계학술대회
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• pp.349-355
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• 2010

EPCIS(EPC Information Services) system is a core component of EPCglobal Architecture Framework offering information of the freights, the time of awareness and the location of awareness on the EPCglobal Network. The role of EPCIS is to exchange information based on EPC. There are four kinds of event data which are object event data, aggregation event data, quantity event data, and transaction event data. These EPCIS events data are stored and managed in EPCIS repository. This paper leads to separate a in-out data overload of integrated EPCIS event and suggests the method to effectively manage EPCIS repository for exchanging data smoothly. In order to verify a effectiveness, we measure the performance of the system using a simple testing simulation by comparing existing method and suggested method.

• 대한안전경영과학회지
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• 제11권4호
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• pp.221-228
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• 2009

Electronic Product Code Information Services(EPCIS) is an EPCglobal standard for sharing EPC related information between trading partners. EPCIS provides a new important capability to improve efficiency, security, and visibility in the global supply chain. EPCIS data are classified into two categories, master data (static data) and event data (dynamic data). Master data are static and constant for objects, for example, the name and code of product and the manufacturer, etc. Event data refer to things that happen dynamically with the passing of time, for example, the date of manufacture, the period and the route of circulation, the date of storage in warehouse, etc. There are four kinds of event data which are Object Event data, Aggregation Event data, Quantity Event data, and Transaction Event data. This thesis we propose an event-based data model for EPC Information Service repository in RFID based integrated logistics center. This data model can reduce the data volume and handle well all kinds of entity relationships. From the point of aspect of data quantity, we propose a formula model that can explain how many EPCIS events data are created per one business activity. Using this formula model, we can estimate the size of EPCIS events data of RFID based integrated logistics center for a one day under the assumed scenario.

• 대한안전경영과학회지
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• 제12권4호
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• pp.169-174
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• 2010

EPCIS(EPC Information Services) system is a core component of EPCglobal Architecture Framework offering information of the freights, the time of awareness and the location of awareness on the EPCglobal Network. The role of EPCIS is to exchange information based on EPC. There are four kinds of event data which are object event data, aggregation event data, quantity event data, and transaction event data. These EPCIS events data are stored and managed in EPCIS repository. This paper deals with the method which diversifies the data flow load of intensive EPCIS events and effectively manages EPCIS repository for exchanging data smoothly. In order to verify a effectiveness, we measure the performance of the system using a simulation by comparing the existing method with the suggested method.

• 대한안전경영과학회지
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• 제11권2호
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• pp.137-144
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• 2009

EPCIS(EPC Information Services) system is a core component of EPCglobal Architecture Framework offering information of the freights, the time of awareness and the location of awareness on the EPCglobal Network. The role of EPCIS is to exchange information based on EPC. There are four kinds of event data which are object event data, aggregation event data, quantity event data, and transaction event data. These EPCIS events data are stored and managed in EPCIS repository. This study suggest the quantitative modeling about total number of EPCIS event data under the assumption to aware the RFID tags of items, cases(boxes), vehicles(carriers, forklifts, auto guided vehicles, rolltainers) at a time on the reading points. We also estimate the number of created EPCIS event data by the suggested quantitative modeling under scenario of process in the integrated logistics center based on RFID system And this study compare the TO-BE model with the AS-IS model about the total sizes of created EPCIS event data using the simulation, in which we suggested the TO-BE model as the development of the repository by skipping the overlapped records.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권3호
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• pp.490-508
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• 2013

One of the most important scalability issues facing the current Internet is the rapidly increasing rate of BGP updates (BGP churn), to which route flap and path exploration are the two major contributors. Current countermeasures would either cause severe reachability loss or delay BGP convergence, and are becoming less attractive for the rising concern about routing convergence as the prevalence of Internet-based real time applications. Based on the observation that highly active prefixes usually repeatedly explore very few as-paths during path exploration, we propose a router-level mechanism, Path Exploration Aggregation (PEA), to scale BGP without either causing prefix unreachable or slowing routing convergence. PEA performs aggregation on the transient paths explored by a highly active prefix, and propagates the aggregated path instead to reduce the updates caused by as-path changes. Moreover, in order to avoid the use of unstable routes, PEA purposely prolongs the aggregated path via as-path prepending to make it less preferred in the perspective of downstream routers. With the BGP traces obtained from RouteViews and RIPE-RIS projects, PEA can reduce BGP updates by up to 63.1%, shorten path exploration duration by up to 53.3%, and accelerate the convergence 7.39 seconds on average per routing event.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2009년도 정보통신설비 학술대회
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• pp.157-161
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• 2009

In recent years, there is a remarkable progress in ICTs (Information and Communication Technologies), and then many attempts to apply ICTs to other industries are being made. In the field of disaster managements, ICTs such as RFID (Radio Frequency IDentification) and USN (Ubiquitous Sensor Network) are used to provide safe environments. Actually, various types of early warning systems using USN are now widely used to monitor natural disasters such as floods, landslides and earthquakes, and also to detect human-caused disasters such as fires, explosions and collapses. These early warning systems issue alarms rapidly when a disaster is detected or an event exceeds prescribed thresholds, and furthermore deliver alarm messages to disaster managers and citizens. In general, these systems consist of a number of various sensors and measure real-time stream data, which requires an efficient and rapid data processing technique. In this study, an event-driven architecture (EDA) is presented to collect event effectively and to provide an alert rapidly. A publish/subscribe event processing method to process simple event is introduced. Additionally, a complex event processing (CEP) technique is introduced to process complex data from various sensors and to provide prompt and reasonable decision supports when many disasters happen simultaneously. A basic concept of CEP technique is presented and the advantages of the technique in disaster management are also discussed. Then, how the main processing methods of CEP such as aggregation, correlation, and filtering can be applied to disaster management is considered. Finally, an example of flood forecasting and early alarm system in which CEP is incorporated is presented It is found that the CEP based on the EDA will provide an efficient early warning method when disaster happens.