• 한국통신학회논문지
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• 제35권12A호
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• pp.1160-1170
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• 2010

기존의 다중경로 설정 방법은 소스로부터 목적지까지 명확하게 분리된 다중경로를 보장하지 못할 뿐만 아니라, 다중경로의 라우팅 정보를 설정하고 유지하기 위한 오버헤드가 많다. 본 논문에서는 다중경로를 설정하는 과정에서 플러딩 방식을 제거하고, 트래픽 부하를 분산시키며, 경로 갱신에 참여하는 노드의 수를 최소화함으로써, 에너지 효율적인 EDM(Explicit Disjoint Multipath) 방식을 제안한다. EDM은 논리적으로 다중경로가 구성될 수 있는 논리적인 파이프라인을 구성하고, 물리적으로 파이프라인을 통해 목적지까지 경유지 기반 지오그래픽 라우팅을 수행한다. EDM은 네트워크 트래픽 부하를 분산시키고, 에너지 소모를 균등화할 수 있으며, 네트워크 생명주기를 연장시킬 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.5058-5077
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• 2019

Traditional regenerating codes are designed to tolerate node failures with optimal bandwidth overhead. However, there are many types of partial failures inside the node, such as latent sector failures. Recently, proposed regenerating codes can also repair intra-node failures with node-level redundancy but incur significant bandwidth and I/O overhead. In this paper, we construct a new scheme of regenerating codes, called IR-RBT codes, which employs intra-node redundancy to tolerate intra-node failures and serve as the help data for other nodes during the repair operation. We propose 2 algorithms for assigning the intra-node redundancy and RBT-Helpers according to the failure probability of each node, which can flexibly adjust the helping relationship between nodes to address changes in the actual situation. We demonstrate that the IR-RBT codes improve the bandwidth and I/O efficiency during intra-node failure repair over traditional regenerating codes but sacrifice the storage efficiency.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.281-286
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• 2009

The proposed technique uses cyclic frame structure, where three periods such as beacon period (BP), mesh contention access period (MCAP) and slotted period (SP) are in a data frame. This paper studies on a mechanism to allow communication nodes (6lowpan) in a PAN with different logical channel for global healthcare applications monitoring technology. The proposed super framework structure system has installed 6lowpan sensor nodes to communicate with each other. The basic idea is to time share logical channels to perform 6lowpan sensor node. The concept of 6lowpan sensor node and various biomedical sensors fixed on the patient BAN (Body Area Network) for monitoring health condition. In PAN (hospital area), has fixed gateways that received biomedical data from 6lowpan (patient). Each 6lowpan sensor node (patient) has IP-addresses that would be directly connected to the internet. With the help of IP-address service provider can recognize or analyze patient data from all over the globe by the internet service provider, with specific equipments i.e. cell phone, PDA, note book. The NS-2.33 result shows the performance of data transmission delay and data delivery ratio in the case of hop count in a PAN (Personal Area Networks).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5425-5448
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• 2018

Wireless sensor network has been widely used in Internet of Things (IoT) applications to support large and dense networks. As sensor nodes are usually tiny and provided with limited hardware resources, the existing multiple access methods, which involve high computational complexity to preserve the protocol performance, is not available under such a scenario. In this paper, we propose an intelligent Medium Access Control (MAC) protocol selection scheme based on machine learning in wireless sensor networks. We jointly consider the impact of inherent behavior and external environments to deal with the application limitation problem of the single type MAC protocol. This scheme can benefit from the combination of the competitive protocols and non-competitive protocols, and help the network nodes to select the MAC protocol that best suits the current network condition. Extensive simulation results validate our work, and it also proven that the accuracy of the proposed MAC protocol selection strategy is higher than the existing work.

• 한국멀티미디어학회논문지
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• 제24권2호
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• pp.312-319
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• 2021

This study aims to help users to have a more satisfying encounter based on the problems found by comparing and analyzing similar applications. That is, an application that derives intermediate points through the subway, which is a public transportation means, and provides information on nearby convenience facilities was proposed. The middle point calculation process uses the dijkstra algorithm, which stores the minimum number of nodes in the stored path from the first input location to the last location. The stack and arraylist are used to search all paths from the first input position to the last position, and then the path with the smallest number of nodes is selected. After that, the number of stations in the route is divided in half and the resulting station is output. In addition, this study provides information on convenience facilities near intermediate points in order to have differences from similar applications. It categorizes within a 1km radius of the point and provides a function that helps to conveniently identify only facilities around the middle point. In particular, by visualizing the number of convenience facilities with radar charts and numbers, it is possible to grasp the commercial district around the midpoint at a glance.

• 한국융합학회논문지
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• 제7권6호
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• pp.43-48
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• 2016

무선센서 네트워크는 센서 데이터베이스 관리 시스템을 통해 보다 효율적으로 개발 및 운용될 수 있다. 센서 데이터베이스 관리 시스템은 무선센서 입력에 대해 선언된 사용자 정의 질의를 처리하기 위해 사용자들에게 익숙한 SQL 유형의 사용자 접속을 지원한다. 무선센서 네트워크상의 전형적 질의 유형은 임의의 스냅 샷 값 검색이나 오래도록 지속되는 연속 질의 형태를 갖는다. 무선센서 네트워크상에서 질의 처리는 베이스스테이션으로부터 여러 노드들로 질의를 보내는 과정과 여러 노드에서 얻어지는 질의 결과를 베이스스테이션으로 회수하는 과정이 있는데 이러한 질의의 파급이나 베이스스테이션으로의 결과 전송은 많은 에너지 소모를 요구한다. 이 논문은 무선센서 네트워크상에서 영역 질의를 처리함에 있어 질의 및 결과를 파급시키는데 소모되는 에너지를 절약시켜 주기 위한 분산정보수집(DIG: Distributed Information Gathering)이라고 이름붙인 효율적 색인 방법을 제안한다.

• 대한전자공학회논문지TC
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• 제43권4호
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• pp.13-21
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• 2006

MANET(Mobile Ad-Hoc Network)은 고정된 기반이 없이 노드간의 자율적이고 독립적인 네트워크를 구성한다. 이러한 네트워크에서 경로설정은 이동성이 많은 단말들이 임시로 망을 구성하기 때문에 망 자체간 유기적으로 자주 변하며, 이로 인해 잦은 연결실패로 인한 불안전한 환경이 조성되어 경로설정을 유지하는데 많은 어려움이 있다. 이를 효과적으로 하기 위하여 ZRP(Zone Routing Protocol) 경로설정 프로토콜이 제안 되었다. 그러나 ZRP는 보안에 관한 요소를 포함하고 있지 않기 때문에, 경로설정을 할 때 DoS(Denial of Service)공격에 취약하며, 또한 키 분배에 관한 메커니즘을 가지고 있지 않기 때문에 경로가 설정되었다고 해도 실제 데이터 전송 시 제 3자에 의하여 공격당하기 쉽다. 이를 보안하기 위해서 ZRP가 경로를 설정할 때 안전하게 경로를 설정할 수 있는 S-ZRP(Secure Zone Routing Protocol) 알고리즘을 제안하였다. 제안한 알고리즘은 경로설정 패킷에 대한 무결성 보장 및 근원지 인증 메커니즘을 통해서 보다 안전하게 전송할 수 있다.

• 한국통신학회논문지
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• 제38C권4호
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• pp.378-386
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• 2013

본 논문은 N 통신노드들이 다중 안테나 비재생 릴레이국의 협력으로 서로 데이터를 교환하는 다중방향 릴레이 시스템을 제안한다. 기존의 단방향 릴레이를 적용한 다중방향 통신의 경우 2N 전송 단계가 필요하나 제안하는 다중방향 릴레이 시스템은 단일 다중접속 단계와 N-1 방송 단계로 구성된 총 N 전송 단계만 필요로 한다. 특히 효율적인 방송 단계 전송을 위해 통신노드들을 쌍을 짓고 쌍이 아닌 통신노드들에게 간섭을 주지 않는 새로운 릴레이 빔형성 행렬과 통신노드 자가간섭 소거기를 제안한다. 평균 합 전송률로 성능을 평가한 결과, 제안 기법이 기존 기법의 성능을 향상시키며 그 이득은 릴레이 노드 안테나 수와 통신노드 수가 비슷할 때 더 커짐을 볼 수 있다. 이러한 제안 기법은 여러 선박간의 정보를 공유할 필요가 있는 해양 통신 환경에서 통신 거리를 확장하는 데 효과적으로 적용할 수 있을 것으로 기대된다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권24호
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• pp.10607-10611
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• 2015

Background: HER2 expression in the primary tumor and its lymph node metastases vary in gastric cancer, reflecting intratumoral heterogeneity. This finding also suggests that proliferation of a different clone in metastatic nodes is possible. In the current study, we aimed to determine the cause of discordance in HER-2 expression in the primary tumor and lymph node metastases for patients with gastric cancer. Materials and Methods: Eighty-one patients with gastric cancer who had undergone radical gastrectomy and were found to have lymph node metastasis upon pathological examination were included. Histopathological samples were obtained from biopsies obtained during patient gastrectomies and lymph node dissection. HER2 status was evaluated by both immunohistochemistry (IHC) and silver in situ hybridization (SISH). Results: Sixty-four (79%) patients were SISH (-), while 17 (21%) were SISH (+) in the primary tumor. However, in metastatic lymph nodes, HER2 status was SISH positive in 5 (28.3%) of the 64 SISH (-) primary tumor specimens. One of the 17 SISH (+) primary tumors was SISH (-) in the metastatic lymph nodes. Thus, SISH results for HER2 in both primary tumors and lymph node metastases were comparable, showing a concordance of 92.5%. In total, six patients demonstrated discordance between the primary tumor and lymph node metastases. The prevalence of HER2 discordance was significantly higher for patients in the pN2 and N3 stages (p=0.007). Although discordant patients had worse survival rates than concordant patients, the differences were not significant (p>0.05).Conclusions: Our study indicates that the frequency of concordance in HER2 status, as determined by IHC or SISH, is high in primary tumors and their corresponding lymph node metastases for patients with gastric cancer. If there is a discrepancy in HER2 status, its evaluation by both IHC and SISH may be useful for detecting patients who would benefit from trastuzumab, and it would therefore help guide decision-making processes in administering treatment.

• 대한간호학회지
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• 제47권6호
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• pp.806-816
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• 2017

Purpose: As comprehensive nursing care service has gradually expanded, it has become necessary to explore the various opinions about it. The purpose of this study is to explore the large amount of text data regarding comprehensive nursing care service extracted from online news and social media by applying a semantic network analysis. Methods: The web pages of the Korean Nurses Association (KNA) News, major daily newspapers, and Twitter were crawled by searching the keyword 'comprehensive nursing care service' using Python. A morphological analysis was performed using KoNLPy. Nodes on a 'comprehensive nursing care service' cluster were selected, and frequency, edge weight, and degree centrality were calculated and visualized with Gephi for the semantic network. Results: A total of 536 news pages and 464 tweets were analyzed. In the KNA News and major daily newspapers, 'nursing workforce' and 'nursing service' were highly rated in frequency, edge weight, and degree centrality. On Twitter, the most frequent nodes were 'National Health Insurance Service' and 'comprehensive nursing care service hospital.' The nodes with the highest edge weight were 'national health insurance,' 'wards without caregiver presence,' and 'caregiving costs.' 'National Health Insurance Service' was highest in degree centrality. Conclusion: This study provides an example of how to use atypical big data for a nursing issue through semantic network analysis to explore diverse perspectives surrounding the nursing community through various media sources. Applying semantic network analysis to online big data to gather information regarding various nursing issues would help to explore opinions for formulating and implementing nursing policies.