• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.741-744
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• 2007

홈 네트워크 분야가 발전하면서 건물이나 집안 내부 정보를 감지하는 센서들도 발전하고 있다. 화재 역시 다양한 원인에 대해 여러 가지 방법으로 감지하는 센서들이 개발되고, 화재 진압 시스템도 발전되고 있다. 본 연구에서는 화재 감지 시스템에 Cricket 센서 네트워크 이용한 위치 추적 기법을 추가하여 화재 발생 시 건물 내 사람의 위치를 추적하는 시스템을 구현한다. 이는 신속한 인명 구조에 도움을 주고, 홈 네트워크의 새로운 한 분야를 제시한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.733-736
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• 2010

VANET(Vehicular Ad-hoc Network)은 노드를 차량으로 가정하는 개념의 MANET(Mobile Ad-hoc Network)로서 노드의 빠른 이동으로 인해 급격한 토폴로지의 변화가 일어난다. 하지만 차량 노드의 이동은 도로 상에서 제한되어 있기 때문에 토폴로지에 대한 상대적인 예측 가능성을 가지고 있다. 이는 교통이 혼잡한 도로 환경에서 그리디 기법을 이용하여 다음 홉을 결정할 때 보다 높은 정확성을 제공할 수 있어 경유 노드의 수와 포워딩 실패를 최소화한다. 본 논문은 위기 정보와 운전 시스템 정보를 기반으로 하는 차량 간 통신 라우팅 최적화 기법을 제안하고 기존의 GPSR(Greedy Perimeter Stateless Routing) 기법과 SAR(Spatial Aware Routing) 기법과의 비교를 통해 효율성과 신뢰성의 향상을 증명하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.467-468
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• 2009

무선 애드혹 네트워크는 고정된 유선 네트워크에서 생각할 수 없었던 잦은 네트워크 구성의 변화, 대역폭과 에너지 사용의 제한 등 기존의 유선 네트워크와는 다른 특성들을 갖는다. 따라서 유선 네트워크에서 제공받았던 고품질의 서비스를 무선 애드혹 네트워크에서 제공받기 위해서는 제한된 자원을 효과적으로 이용할 수 있는 연구가 필요하다. 본 논문에서는 GPS 등의 기술을 이용하여 네트워크를 구성하는 이동 노드들의 위치 정보를 파악하고, 이를 라우팅에 활용하는 기존의 위치기반 라우팅 기법 중 하나인 LAR 알고리즘을 개량하였다. 제안 알고리즘은 노드들의 위치뿐만 아니라 에너지까지 함께 고려하며, 이를 위해 불필요한 제어 메시지의 확산을 최소화하고, 노드간 거리에 적절한 전송 전력을 사용하여 통신을 하게 함으로써 효율적인 라우팅이 이루어지도록 하였다. 실험 결과 기존 LAR 알고리즘에 비해 제안 기법이 노드의 생존률이 평균 12.1% 향상되었다.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1364-1376
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• 2020

A pericardial recess is frequently seen in patients undergoing chest computed tomography (CT). It is important to be aware of the normal anatomy of the pericardium as it is often mistaken for normal variants and/or disease. Therefore, we will describe the anatomy and location of the pericardial recess and the specific findings in various diseases associated with the pericardial recess.

• The Journal of the Korea Contents Association
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• v.11 no.7
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• pp.21-29
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• 2011

U-health care services have been attracted to effectively solve some problems in promoting health and preparing aging society. Although the recent U-health care services have been developed to treat diseases, it requires environment information related to health for preventing fundamental diseases and for promoting health. In this study, a U-health environment service that reflects context recognition information is proposed. The proposed service draws environment information using local weather and healthcare information in users' residential areas. In the context recognition based U-health environment services, various services are provided to users not only health, living weather based menu, and exercise services but user location based warning messages for dangerous regions and remote emergency services. That is, based on such context recognition, some events that are to be occurred to users are detected and then it will provide proper services. Thus, it improves the satisfaction of U-health services and its service qualities.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.9
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• pp.2213-2218
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• 2013

Smart devices such as smart phone, smart TV, tablet, game consoles embrace all categories of Intelligent Communication Device, which enables intelligent applications to be developed, by up loading Context-aware Computing technology that recognizes and reacts nearby diverse phenomena and composing these information, as well as their basic functions. This paper, after saving pre-registered students' movement course and business places harmful to them into students safety network service system, by using location-based service and searching students' movement, considering the degree of breaking away from their regular course, the access to and their stay in crime-crone area, provides the comparative analysis of the system and suggests the ways for safe students guidance.

• The KIPS Transactions:PartD
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• v.13D no.1 s.104
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• pp.23-28
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• 2006

In this paper, a power-aware query processing using optimized distributed R-tree in a sensor network is proposed. The proposed technique is a new approach for processing range queries that uses spatial indexing. Range queries are most often encountered under sensor networks for computing aggregation values. The previous work just addressed the importance but didn't provide any efficient technique for processing range queries. A query processing scheme is thus designed for efficiently processing them. Each node in the sensor network has the MBR of the region where its children nodes and the node itself are located. The range query is evaluated over the region which intersects the geographic location of sensors. It ensures the maximum power savings by avoiding the communication of nodes not participating over the evaluation of the query.

• Journal of Computing Science and Engineering
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• v.6 no.3
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• pp.227-242
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• 2012

Vehicular Ad Hoc Networks (VANETs) are highly dynamic and unstable due to the heterogeneous nature of the communications, intermittent links, high mobility and constant changes in network topology. Currently, some of the most important challenges of VANETs are the scalability problem, congestion, unnecessary duplication of data, low delivery rate, communication delay and temporary fragmentation. Many recent studies have focused on a hybrid mechanism to disseminate information implementing the store and forward technique in sparse vehicular networks, as well as clustering techniques to avoid the scalability problem in dense vehicular networks. However, the selection of intermediate nodes in the store and forward technique, the stability of the clusters and the unnecessary duplication of data remain as central challenges. Therefore, we propose an adaptable destination-based dissemination algorithm (DBDA) using the publish/subscribe model. DBDA considers the destination of the vehicles as an important parameter to form the clusters and select the intermediate nodes, contrary to other proposed solutions. Additionally, DBDA implements a publish/subscribe model. This model provides a context-aware service to select the intermediate nodes according to the importance of the message, destination, current location and speed of the vehicles; as a result, it avoids delay, congestion, unnecessary duplications and low delivery rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.12
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• pp.2272-2293
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• 2011

Communication technology of future networks is predicted to provide a large variety of services including WiFi service in vehicular network. In this paper, we assume that vehicles are embedded with WiMAX antenna and in-vehicle terminals receive WiMAX traffic through WiFi interface. This assumption will impose severe performance degradation due to interference among mobile BSSs when WiFi access points (APs) are densely located. Existing interference avoidance techniques cannot properly resolve the above problems and do not cope with dynamically moving vehicular scenario since they focus only on the fixed network topology. In this paper, we propose a mobility-aware interference avoidance scheme for WiFi services. The proposed scheme computes the interference duration by exploiting mobility vector and location information of neighboring APs. If the interference duration is not negligible, our scheme searches for another channel in order to avoid interference. However, if the interference duration is negligible, our scheme continues to use the channel to reduce switching overhead. To measure the effectiveness of the proposed scheme against other existing techniques, we evaluated performance by using OPNET simulator. Through the simulation, we obtained about 60% reduction in the maximum interference frequency and about 67% improvement in throughput. Furthermore, our scheme provides fair channel usage.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3916-3936
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• 2014

Smartphone applications like games, image processing, e-commerce and social networking are gaining exponential growth, with the ubiquity of cellular services. This demands increased computational power and storage from mobile devices with a sufficiently high bandwidth for mobile internet service. But mobile nodes are highly constrained in the processing and storage, along with the battery power, which further restrains their dependability. Adopting the unlimited storage and computing power offered by cloud servers, it is possible to overcome and turn these issues into a favorable opportunity for the growth of mobile cloud computing. As the mobile internet data traffic is predicted to grow at the rate of around 65 percent yearly, even advanced services like 3G and 4G for mobile communication will fail to accommodate such exponential growth of data. On the other hand, developers extend popular applications with high end graphics leading to smart phones, manufactured with multicore processors and graphics processing units making them unaffordable. Therefore, to address the need of resource constrained mobile nodes and bandwidth constrained cellular networks, the computations can be migrated to resourceful servers connected to cloud. The server now acts as a bridge that should enable the participating mobile nodes to offload their computations through Wi-Fi directly to the virtualized server. Our proposed model enables an on-demand service offloading with a decision support system that identifies the capabilities of the client's hardware and software resources in judging the requirements for offloading. Further, the node's location, context and security capabilities are estimated to facilitate adaptive migration.