• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.3
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• pp.8-13
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• 2012

In this paper, we investigate cooperative spectrum sensing scheme for sensor network-aided cognitive radio systems with energy harvesting capability. In the proposed model, each sensor node harvests ambient energy from environment such as solar, wind, mechanical vibration, or thermoelectric effect. We propose adaptive cooperative spectrum sensing scheme in which each sensor node adaptively carries out energy detection depending on the residual energy in its energy storage and then conveys the sensing result to the fusion center. From simulation results, we show that the proposed scheme minimizes the false alarm probability for given target detection probability by adjusting the number of samples for energy detector.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.41-51
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• 2009

Recently, there are many researches on security to remove vulnerability which is caused by wireless communication in wireless sensor networks. To guarantee secure communication, we should basically provide key management for each node, mutual authentication and key agreement protocol between two nodes. Although many protocols are presented to supply these security services, some of them require plentiful storage memory, powerful computation and communication capacity. In this paper, we propose a lightweight and efficient authentication and key agreement protocol between two sensor nodes, which is an enhanced version of Juang's scheme. In Juang's protocol, sensor node's information used to share a secret key should be transmitted to registration center via a base station. On the contrary, since node's information in our protocol is transmitted up to only base station, the proposed scheme can decrease computation and communication cost for establishing the shared key between two nodes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3690-3713
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• 2019

According to the main group key management schemes logical key hierarchy (LKH), exclusion basis systems (EBS) and other group key schemes are limited in network structure, collusion attack, high energy consumption, and the single point of failure, this paper presents a group key management scheme for wireless sensor networks based on Lagrange interpolation polynomial characteristic (AGKMS). That Chinese remainder theorem is turned into a Lagrange interpolation polynomial based on the function property of Chinese remainder theorem firstly. And then the base station (BS) generates a Lagrange interpolation polynomial function f(x) and turns it to be a mix-function f(x)' based on the key information m(i) of node i. In the end, node i can obtain the group key K by receiving the message f(m(i))' from the cluster head node j. The analysis results of safety performance show that AGKMS has good network security, key independence, anti-capture, low storage cost, low computation cost, and good scalability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5596-5615
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• 2016

Security is one of the major challenges in the Wireless Sensor Networks (WSNs). WSNs are more vulnerable to adversarial activities. All cryptographic security services indirectly depend on key management. Symmetric key management is the best key establishment process for WSNs due to the resource constraints of the sensors. In this paper, we proposed dynamic session key establishment scheme based on randomly generated nonce value and sensor node identity, in which each sensor node is equipped with session key on expire basis. The proposed scheme is compare with five popular existing key management systems. Our scheme is simulated in OMNET++ with MixiM and presented experimental results. The analytical study and experimental results show the superiority of the proposed scheme over the existing schemes in terms of energy, storage, resilience and communication overhead.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.39-40
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• 2017

본 논문에서는 서버의 비동기 입출력(이하 I/O) 모델을 통해 더 많은 접속과 성능을 위한 패턴과 클라이언트 브라우저의 HTML 템플렛팅과 반응성 UI들의 메모리 관리 패턴을 제안한다. 본 연구는 다이어트 현황을 기록하는 저널(Journal) 서비스를 제공하는 웹 어플리케이션이다. 노드.js (Node.js)의 소켓.io (Socket.io)를 통한 비동기 push 패턴을 사용한 효율적인 I/O 성능, html5의 로컬 저장소 (Local Storage), tcp/ip 헤더의 쿠키 (Cookie), 상태를 저장하는 웹 토큰 (Json Web Token)을 통한 무상태 서버 구조로 구성되어 있다. 이로 인하여 서버 확장성 및 동시 처리, 빠른 질의 성능, 기본 네트워크 패킷 보안을 구축한다. 과한 CPU 처리를 요하는 일 중 템플릿팅은 클라이언트 브라우저에게 분담하도록 하고 효율적인 DOM 접근과 메모리 관리를 위한 싱글턴 패턴을 적극 활용하여 빠르고 즉각적인 반응성을 가진 웹 어플리케이션을 운용한다.

• Journal of the military operations research society of Korea
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• v.25 no.1
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• pp.29-36
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• 1999

In this paper, we are concerned with the K-shortest loopless path problem. The MPS algorithm, recently proposed by Martins et al., finds paths efficiently because it solves the shortest path problem only one time unlike other algorithms. But its computational complexity has not been known yet. We propose a few techniques by which the MPS algorithm can be implemented efficiently. First, we use min-heap data structure for the storage of candidate paths in order to reduce searching time for finding minimum distance path. Second, we prevent the eliminated paths from reentering in the list of candidate paths by lower bounding technique. Finally, we choose the source mode as a deviation node, by which selection time for the deviation node is reduced and the performance is improved in spite of the increase of the total number of candidate paths.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.843-845
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• 2011

Due to the short lifetime of the battery-based sensor network, study on the environmental energy-harvesting sensor network is being performed widely. In this paper, we analyze the system-level requirements on the sensor node which is needed for the efficient solar-powered wireless sensor network for the target application. In addition, we explain how the HW/SW components of our real solar-powered sensor node can satisfy the requirements mentioned above.

• Journal of Information Processing Systems
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• v.17 no.6
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• pp.1035-1043
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• 2021

An Internet of Things (IOT) sensor network is an effective solution for monitoring environmental conditions. However, IOT sensor networks generate massive data such that the abilities of massive data storage, processing, and query become technical challenges. To solve the problem, a Hadoop cloud platform is proposed. Using the time and workload genetic algorithm (TWLGA), the data processing platform enables the work of one node to be shared with other nodes, which not only raises efficiency of one single node but also provides the compatibility support to reduce the possible risk of software and hardware. In this experiment, a Hadoop cluster platform with TWLGA scheduling algorithm is developed, and the performance of the platform is tested. The results show that the Hadoop cloud platform is suitable for big data processing requirements of IOT sensor networks.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.657-664
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• 2003

Supporting the availability, integrity, and confidentiality of the information is crucial. The survivability storage systems require to encode and distribute data over multiple storage nodes or data base to survive failures and malicious attacks Information dispersal scheme is one of the most efficient schemes allowing high availability and security with reasonable overhead. In this paper, we propose an algorithm determining the optimal (m, n)-lDS in terms of availability, given a set of IDS's. The proposed algorithm will be very useful for designing a highly available and secure storage system since many factors such as node number, storage space, operation speed, etc. interact with each other and thereby finding an optimal information dispersal scheme is very difficult.

• The KIPS Transactions:PartD
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• v.13D no.3 s.106
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• pp.325-336
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• 2006

For supporting LBS service, recent studies on spatial network databases (SNDB) have been done actively. In order to gain good performance on query processing in SNDB, we, in this paper. design efficient storage and index structures for spatial network data, point of interests (POIs), and moving objects on spatial networks. First, we design a spatial network file organization for maintaining the spatial network data itself consisting of both node and edges. Secondly, we design a POI storage and index structure which is used for gaining fast accesses to POIs, like restaurant, hotel, and gas station. Thirdly, we design a signature-based storage and index structure for efficiently maintaining past, current, and expected future trajectory information of moving objects. Finally, we show that the storage and index structures designed in this paper outperform the existing storage structures for spatial networks as well as the conventional trajectory index structures for moving objects.