• Journal of Communications and Networks
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• 제11권1호
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• pp.57-71
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• 2009

Networking together hundreds or thousands of cheap sensor nodes allows users to accurately monitor a remote environment by intelligently combining the data from the individual nodes. As sensor nodes are typically battery operated, it is important to efficiently use the limited energy of the nodes to extend the lifetime of the wireless sensor network (WSN). One of the fundamental issues in WSNs is the coverage problem. In this paper, the border coverage problem in WSNs is rigorously analyzed. Most existing results related to the coverage problem in wireless sensor networks focused on planar networks; however, three dimensional (3D) modeling of the sensor network would reflect more accurately real-life situations. Unlike previous works in this area, we provide distributed algorithms that allow the selection and activation of an optimal border cover for both 2D and 3D regions of interest. We also provide self-healing algorithms as an optimization to our border coverage algorithms which allow the sensor network to adaptively reconfigure and repair itself in order to improve its own performance. Border coverage is crucial for optimizing sensor placement for intrusion detection and a number of other practical applications.

• 한국조경학회지
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• 제31권2호
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• pp.83-93
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• 2003

This study was conducted for an understanding of a threatened plant species,“Penthorum chinense”, which is a vegetation structure and environmental characteristic in the southern part of Ibaraki, Japan. We selected distribution and contiguity area where P. chinense is not distributed and we set up 69 sites by the quardrat method. The surveyed general characters in each site include mean-height, mean-coverage, moisture condition water depth coverage and depth of litter layer. We calculated the degree of succession by the survey data and grasped the main distribution area, vegetation structure, growth environment of P. chinense by TWINSPAN classification and DCA ordination. The results of this study are as follows. First, P. chinense habitat was categorized into the riverside and abandoned paddy fields. The riverside was influenced by natural disturbance caused by flooding and drought. These conditions led to a poor P. chinense growth. The abandoned paddy fields as the artificial disturbance area have high potential value, because the area can preserve P. chinense growth space by succession control and water management. second, we executed TWINSPAN analysis based on vegetation coverage data of survey sites. The vegetation types were classified into the three categories: annual plant flora(P. chinense dominates in wet state), perennial plant flora(Solidago altissima dominates in dry state), and perennial plant flora(Phragmites communis dominates in wet state). Third, the data was ordinated by DCA. The sample sequences along the first and second DCA axes effectively reflected moisture condition, number of species, mean height, coverage of litter layer and degree of succession. Especially, P. chinense flora has the high correlation with moisture condition and number of species.

• Journal of Biosystems Engineering
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• 제28권3호
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• pp.199-208
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• 2003

In order to solve the shortage of roughage supply for dairy farm in Korea, winter cereal forage production after harvesting of rice in the fallow paddy field is studied. This study consist of two parts. One is the model development of the mechanized production which was already reported at the preview paper. This is the 2nd parts of the study. Also, the mechanized production model for cereal forage production in winter was reported in the previous study. In this paper, coverage area and mechanized wrap silge production cost are analyzed and compared to the other available feeds in Korea. Results of the research are summarized as follows; The coverage area for the winter cereal wrap silage production system in Korea is estimated to be 33.7 ha in case of working with a tractor and a set of implements. If two or three tractors are available, the coverage area is estimated to be 68.0 and 101.3 ha, respectively. The break even point (BEP) of the farming size is analyzed as 10 ha and its production(operating) cost is estimated to be 317 to 443 won/TDN-kg at the BEP point. The cost is lowered to 182 won/TDN-kg at 100ha-working, and is much lower compared with prices of imported feeds of 360∼600 won/TDN-kg. Therefore, winter cereal wrap silage model is judged to be feasible and desirable for a large scale production of forage in winter fallow paddy field.

• Asian Pacific Journal of Cancer Prevention
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• 제13권8호
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• pp.3617-3619
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• 2012

Background: The completeness of cancer registration is a major validity index of any reported cancer incidence. The present study aimed to evaluate the esophageal cancer incidence registered in the Tehran Metropolitan Area Cancer Registry. Materials and methods: The data on esophageal cancer abstracted from three sources of 1) pathology departments, 2) medical records, and 3) death certificates during 2003 till 2007 were utilized. The completeness of the data sources were evaluated using coverage (defined as the proportion of a community population with esophageal cancer identified by the source) and density (defined as the proportion of non-empty fields of the data by source). Results: A total 1,404 cases of esophageal cancer were reported for the duration of the study. Pathology provided 771, medical records 432, and death certificates 609. The coverage was 0.55 for pathology, 0.31 for medical records, and 0.43 for death certificates. The respective density values were 0.82, 0.96 and 0.98, respectively. Pathology (0.45) was the most complete source followed by medical records (0.42), and death certificates (0.29). Discussion: A low degree of completeness dictates putting more effort into case finding plus abstracting data more thoroughly.

• 한국의류산업학회지
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• 제22권1호
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• pp.94-101
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• 2020

This helps plus-size consumers purchase ready-made clothes and improves fitness by analyzing the upper body shapes of abdomen-obese adult males; in addition, it creates a size system based on each size interval of obesity shapes. The criteria for the 572 male subjects surveyed were over 25 kg/㎡ of the BMI, over 90 cm of waist, and over 0.85 waist hip ratio. The results were as follows. First, the higher the age group, the higher the degree of abdominal obesity in each age group. The degree of obesity decreases age increase; however, was the risk of abdominal obesity increased. Second, Compared to standard body types, the average body size of Abdomen-obese males is significantly larger, especially in the waist area than in the chest area. Third, to propose a size system for abdominal obese adult males, 16 sections with a final 2% rate of appearance were finally adopted as suit-tops size system for abdominal obese adult males by applying a 3 cm dimension gap between each designation as specified in the KS standard. The coverage ratio for the 16 sections was 72.6% and the coverage effienciency was 4.5%. The results of this study can be used in a various clothes; in addition, the activation and segmentation of the plus-size market are also believed to be significant.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1936-1939
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• 2002

Much recent attention on wireless technologies s put on topology-less wireless network, in which all nodes an be mobile and can communicate over wireless links, due to its ease of deployment, high flexibility and low expenses. One key in topology-less wireless network is mobile base stations (MBSs), which provides access points or mobile terminals (MTs) to wireless backbone network. MBSs can move to anywhere in accordance with changes in geographical distribution of MTs. They serve as dynamic odes. However, in order to utilize network resources and take full advantage of this topology-less network, MBSs must move to suitable position according to the current tate of network use. Moreover, MBSs have to consider the distance among them to avoid the crash and gap area of MBSs. Therefore, this paper proposes MBS movement algorithm by implementing push-pull method to fulfill the corporation of MBSs and considering the center of covered MTs or centroid to satisfy the MT coverage. From the simulation results, the proposed algorithm increases the performance of system when comparing with the centroid-based algoriom〔7〕, such as coverage area, MT coverage and call drops rate.

• 한국컴퓨터정보학회논문지
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• 제13권2호
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• pp.243-250
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• 2008

최근 슬램 알고리즘의 실현을 통해 주변 환경에 대한 맵 정보가 획득 가능할 경우에 격자 그리드 기반의 Boustrophedon 경로 기반 커버리지 알고리즘이 매우 효율적인 것으로 알려져 있다. 그러나 Boustrophedon 경로 기반 알고리즘은실내 공간에 장애물이 복잡하게 존재할 경우에는 급격히 성능 저하현상이 발생한다. 따라서 본 논문에서는 복잡한 실내 공간에서도 효율적으로 빠른 시간 내에 청소를 완료할 수 있는 Group-k 알고리즘을 제안하고 구현한다. Group-k 알고리즘은 전체 공간을 장애물의 복잡성에 근거하여 전체 공간을 그룹화하고 각 그룹별 우선순위를 부여하여 전체 작업 순서를 효율적으로 제어한다. 구현 기반의 실험에 의하면, 본 논문에서 제안된 알고리즘은 Boustrophedon 경로 기반 알고리즘에 비해 약 20%의 성능 향상을 보여준다.

• The Korean Journal of Ecology
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• 제21권5_3호
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• pp.665-673
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• 1998

This study was conducted to clarified the relationship between bird community and forest structure and present the counterplan for protection and management of bird community from February 1993 to July 1995 at deciduous and coniferous forest within Mt. Nam area, Seoul, Korea. DBH distribution has not significant differences in each study site. Deciduous forest had more foliage coverage in all layers than coniferous forest. Total 41 species of birds, which were 16 species of resident, 14 species of summer visitor, 4 species of winter visitor, and 7 species of passage migrant were recrded in two study sites. Leaf use rate of birds was increased the increase of coverage. The number of breeding species and pairs, breeding density, and diversity index were greater in deciduous forest than coniferous forest. The number of species and pairs on bush-nesting and foraging guild were greater than other guilds. And the nuber of species and pairs on hole nesting guild were the fewest in nesting guild. Use rate of artificial nests for improvement of habitat quality was greater in coniferous forest than deciduous forest. Maintenance of bush layer, increase of coverage and leaf layer diversity, supply of artificial nests, management of large trees, and control of natural enemy were necessary for protection and management of bird community in Mt. nam area.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 춘계학술대회
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• pp.116-119
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• 2015

다수의 이동센서노드를 이용한 환경감시 알고리즘을 제안한다. 제안하는 알고리즘은 사전 정보가 없는 개활 지역에서 이동센서노드들을 배치하여 센싱 커버리지를 최대화 하는 것을 목적으로 한다. 이동센서노드는 보다 높은 센싱 커버리지를 획득하기 위하여 최대의 센싱 커버리지를 획득할 때 까지 반복적으로 재배치된다. 커버리지 최대화를 위하여 ILP(Integer Linear Programming) 기반의 최적화 문제를 구성한다. 시뮬레이션 결과에 의하면 제안된 알고리즘은 이동센서노드들을 보다 높은 관심지역으로 이동시킬 수 있으며 최대의 센싱 커버리지 획득이 가능함을 시뮬레이션을 통하여 검증한다.

• Korean Circulation Journal
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• 제52권4호
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• pp.265-279
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• 2022

Digital health is rapidly growing worldwide and its area is expanding from wellness to treatment due to digital therapeutics (DTx). This study compared DTx in the Korean context with other countries to better understand its political and practical implications. DTx is generally the same internationally, often categorized as software as a medical device. It provides evidence-based therapeutic interventions for medical disabilities and diseases. Abroad, DTx support entailed state subsidies and fundraising and national health insurance coverage. In the case of national health insurance coverage, most cases were applied to mental diseases. Moreover, in Japan, DTx related to hypertension will possibly be under discussion for national health insurance coverage in 2022. In overseas countries, coverage was decided only when the clinical effects were equivalent to those provided by existing technology, and in the UK, real usage data for DTx and associated evaluations were reflected by national health coverage determination. Prices were either determined through closed negotiations with health insurance operating agencies and manufacturers or established based on existing technology. Concerning the current situation, DTx dealing with various diseases including hypertension are expected to be developed near in the future, and the demand for use and compensation will likely increase. Therefore, it is urgent to define and prepare for DTx, relevant support systems, and health insurance coverage listings. Several support systems must be considered, including government subsidies, science/technology funds, and health insurance.