• 제목/요약/키워드: Network lifetime

검색결과 674건 처리시간 0.023초

무선 센서 네트워크에서 유효 커버리지 및 접속성 보장을 위한 중앙 집중형 배치 프로토콜 (A Centralized Deployment Protocol with Sufficient Coverage and Connectivity Guarantee for WSNs)

  • 김현태;장계평;김형진;주영훈;나인호
    • 한국지능시스템학회논문지
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    • 제16권6호
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    • pp.683-690
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    • 2006
  • 무선 센서 네트워크에서 에너지 소비의 효율성은 전체 네트워크 수명 시간을 결정하기 때문에 에너지 소비를 최소화하기 위한 연구가 활발히 진행되고 있다. 무선 센서 네트워크에서 에너지 보전을 위해서는 운영에 필요한 최소한 센서 노드만을 활성화된 상태로 유지하고 나머지 노드들은 휴면 상태로 유지하여 불필요한 에너지 소비가 일어나지 않도록 하여야 한다. 그러나 얼마만큼의 센서 노드들을 최적의 운영 노드 집합에 포함시킬 것인지를 계산하는 것은 NP-hard 문제로 알려져 있다. 본 논문에서는 최적에 근접한 커버 집합(cover set)을 생성하기 위하여 CVT 기반의 근사화 알고리즘을 제안하였다. 제안된 알고리즘에서는 센서의 통신 범위가 센싱 범위의 두 배 이상이면 커버 집합에 속한 센서 노드 간의 연결이 즉시 이루어지도록 하고 반면에 통신 범위가 센싱 범위의 두 배 이하이면 커버 집합의 접속성 보장을 위하여 보조 노드를 결정하는 연결 기법을 제시하였다. 마지막으로 제안된 알고리즘의 성능 평가를 위하여 이론적 분석과 실험을 수행하였으며, 실험결과를 통해 제안된 알고리즘이 Greedy 알고리즘보다 CCS(Connected Cover Set)의 크기와 실행 시간 측면에서 우수함을 보였다.

산업용 무선 센서망을 이용한 연속개체 탐지에서 이동 싱크 지원을 위한 발원점 중심의 통신방안 (An Origin-Centric Communication Scheme to Support Sink Mobility for Continuous Object Detection in IWSNs)

  • 김명은;김천용;임용빈;김상하;손영성
    • 정보처리학회논문지:컴퓨터 및 통신 시스템
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    • 제7권12호
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    • pp.301-312
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    • 2018
  • 오늘날 산업용 무선 센서 망 환경에서 화재나 유독가스와 같은 연속 개체 탐지는 위험성과 대규모 피해로 인해 중요한 문제로 다뤄지고 있다. 연속 개체는 한 지점에서 발생하여 점차 넒은 범위로 확산되는 특징을 가지기 때문에 자원 제약적인 무선 센서 망 환경에서 연속 개체를 탐지한 다수의 센서 노드가 고정 싱크에게 데이터를 전송하게 되면 막대한 통신 오버헤드가 발생하게 된다. 따라서 기존 연구에서는 실시간으로 확장되는 연속 개체를 정확하게 탐지하고, 다량의 센싱 데이터를 에너지 효율적인 방식으로 전송하는 데에 중점을 두었다. 그러나 최근 들어 화재 진압과 같은 실시간 대응이 필요한 응용분야를 위해 연속 개체 탐지에 이동 싱크 도입이 필요하다는 의견이 나타나고 있다. 이러한 경우, 이동 싱크의 위치 갱신을 위해 다수의 소스와 이동 싱크 간 통신이 빈번하게 일어남으로써 무선 센서망의 에너지 소모가 급격하게 증가하는 문제가 발생한다. 본 논문에서는 무선 센서 망을 이용한 연속 개체 탐지에서 이동 싱크를 지원하기 위한 발원점 중심의 통신 방안을 제안한다. 실험결과는 제안 방안이 기존 방안에 비해 이동 싱크의 위치정보 갱신 및 센싱 데이터 보고에 더 적은 에너지를 소모함을 보인다.

Treatment and Follow-up of Human Papillomavirus Infected Women in a Municipality in Southern Brazil

  • Ruggeri, Joao Batista;Agnolo, Catia Millene Dell;Gravena, Angela Andreia Franca;Demitto, Marcela de Oliveira;Lopes, Tiara Cristina Romeiro;Delatorre, Silvana;Carvalho, Maria Dalva de Barros;Consolaro, Marcia Edilaine Lopes;Pelloso, Sandra Marisa
    • Asian Pacific Journal of Cancer Prevention
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    • 제16권15호
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    • pp.6521-6526
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    • 2015
  • Background: This study aimed toanalyze the risk behavior for cervical cancer (CC) and the human papillomavirus (HPV) prevalence and resolution among women who received care through the private healthcare network of a municipality in southern Brazil. Materials and Methods: This descriptive and retrospective study was conducted with 25 women aged 20 to 59 years who received care through the private healthcare network and were treated at a specialty clinic in the period from January to December 2012 in a municipality in Northwest Parana, Southern Brazil. Data from medical records with cytological and HPV results were used. Following treatment, these women were followed-up and reassessed after 6 months. Data were statistically analyzed using the t-test and chi-squared test at a 5% significance level. Results: The mean age of the studied women was $27.8{\pm}7.75$ years old, and the majority were married, with paid employment and were non-smokers. The mean age at menarche was $13.0{\pm}0.50$ years old, and the mean age at first intercourse was $17.5{\pm}1.78$ years, with only 8.0% (2) initiating sexual activity at an age ${\leq}15$ years old. The majority had 1 to 2 children (60.0%), while 88.0% reported having had one sexual partner in their lifetime, and all the women were sexually active. A total of 68.0% used a hormonal contraceptive method. All the women had leukorrhea and pain and were infected by a single HPV type. Regarding the lesion grade, 80.0% showed high risk and 20.0% low risk. The most prevalent high-risk HPV strain was 16. Conclusions: These findings provide relevant information on HPV risk factors and infection, as well as the treatment and 6-month follow-up results, in economically and socially advantaged women with no traditional risk factors, corroborating previous reports that different risk factors may be described in different populations. Thus, this study reinforces the fact that even women without the traditional risk factors should undergo HPVmonitoring and assessment to determine the persistence of infection, promoting early diagnosis of the lesions presented and appropriate treatment to thus prevent the occurrence of CC.

병원에 입원한 노인의 무력감 현상 연구 (A Phenomenological Study for Hospitalized Elderly무s Powerlessness)

  • 최영희;김경은
    • 대한간호학회지
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    • 제26권1호
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    • pp.223-247
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    • 1996
  • This study was done to provide information which would lead to nursing care of the elderly being more holistically through an understanding of the phenomena of powerlessness based on the lived experience of powerlessness by the elderly, the meaning the elderly give to such phenomena, and what essence of powerlessness is. The methodology used in this study was Max Van Manen's phenomenological method based on the philosophy of Merleu-Ponty and a concerted approach was realized through the 11 steps suggested in the Van Manen's method. Data collection was done from March 2, 1995 to December 30, 1995. The subjects for this study were four elderly persons who lived with their families and who were over 60 years of age. Data were collected about the lived experience of the elderly, this researcher's experience of powerlessness, the linguistic meaning of powerlessness, idioms of the word or a feeling of powerlessness, and descriptions of powerlessness in the elderly as they appeared in the literature, are works, and phenomenological literature. All data were used to provide insights into the phenomena of powerlessness. Data about the experience of powerlessness by the elderly were collected through open interviews, participation, and observation. In the analysis of the theme of this study, the aspects of the theme, powerlessness in the elderly were clarified, thereby abstracting and finding meaningful statements by the elderly about their feeling of powerlessness, and then those significant statements were expressed as linguistic transformations. The summarized findings from the study are as follows : 1. Five meanings of powerlessness in the elderly were defined. 〈weakness〉, 〈dependence〉, 〈frustration〉, 〈worthlessness〉 and 〈giving up〉. 2. 〈Weakness〉 means that the elderly experience, not only their aging but also, their becoming weak and the loss of physical function frequently caused by diseases. 〈Dependence〉 means that the elderly experience dependence without any influence from the surroundings and that elderly patients who are hospitalized lose their autonomy, follow entirely their doctor's prescriptions, use aid equipment and directions, and depend only on those things. 〈Frustration〉 means that the elderly experience the loss of their roles from the past, there by feeling that there is no work for them to do anymore and therefore feel unable to do anything. 〈Worthlessness〉 means that the elderly experience the feeling of losing their social roles from the past, having no financial ability, thereby being a burden to their children or the people around them, and therefore regarding themselves useless. 〈Giving up〉 means that the elderly experience the feeling of closeness to death in the final stage of their lifetime, lose hope to be healed from their disease, and recognize the incontrollability of their own body. 3. From a general view of the meaning of the theme the powerlessness in the elderly-the most essential meaning of the theme is the 〈sense of loss〉. For the elderly are experiencing a sense of loss in the situation of being elderly and therefore being often hospitalized. Brief definitions of the five phenomena could be 〈weakness〉 meaning the loss of physical strength, 〈dependence〉 the loss of mentality caused by disease and hospitalization, 〈frustration〉 and 〈worthlessness〉 the loss of social performance caused by the loss of social functions from the past, and lastly 〈giving up〉 the loss of the controllability of such situations of aging and suffering disease. In light of the discussion above, it is understandable that the hospitalized elderly experience powerlessness not only as it related to their diseases but also to their normal aging, and this related to other characteristics of being elderly means that the 〈sense of loss〉 is the very essence of their powerlessness. 4. While most cases are of the normal elderly experiencing powerlessness in relation to their social network, cases of elderly who are hospitalized are of those experiencing powerlessness in relation to the loss of their physical desire. 5. The findings discussed above can serve as guidelines for nurses who take care of the ill elderly who are hospitalized and that can provide cues to appropriate nursing service, recognizing that the subjective experience of the objective age of the elderly is so important. Nurses can provide highly qualitative nursing service, based on their deep understanding of the suffering of the elderly due to feelings of powerlessness.

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