• Title/Summary/Keyword: k-covers

검색결과 1,259건 처리시간 0.028초

RESOLUTION OF UNMIXED BIPARTITE GRAPHS

  • Mohammadi, Fatemeh;Moradi, Somayeh
    • 대한수학회보
    • /
    • 제52권3호
    • /
    • pp.977-986
    • /
    • 2015
  • Let G be a graph on the vertex set $V(G)=\{x_1,{\cdots},x_n\}$ with the edge set E(G), and let $R=K[x_1,{\cdots},x_n]$ be the polynomial ring over a field K. Two monomial ideals are associated to G, the edge ideal I(G) generated by all monomials $x_i,x_j$ with $\{x_i,x_j\}{\in}E(G)$, and the vertex cover ideal $I_G$ generated by monomials ${\prod}_{x_i{\in}C}{^{x_i}}$ for all minimal vertex covers C of G. A minimal vertex cover of G is a subset $C{\subset}V(G)$ such that each edge has at least one vertex in C and no proper subset of C has the same property. Indeed, the vertex cover ideal of G is the Alexander dual of the edge ideal of G. In this paper, for an unmixed bipartite graph G we consider the lattice of vertex covers $L_G$ and we explicitly describe the minimal free resolution of the ideal associated to $L_G$ which is exactly the vertex cover ideal of G. Then we compute depth, projective dimension, regularity and extremal Betti numbers of R/I(G) in terms of the associated lattice.

병원 근무 간호사들의 염색체 이상 및 소핵 빈도에 미치는 위험요인 (Analysis of Chromosome Aberrations and Micronuclei in Peripheral Lymphocytes of Nurses in a Hospital)

  • 전혜정;김태환;최수용;정해원
    • 한국환경성돌연변이발암원학회지
    • /
    • 제25권4호
    • /
    • pp.150-156
    • /
    • 2005
  • Analysis of chromosome aberration (CA) and cytokinesis-block micronucleus (CBMN) assay in peripheral lymphocytes of nurses exposed to low levels of anticancer drug and Ethylene Oxide(EO) gas in a hospital were performed. The frequency of CA was increased in the exposed compared to the controls whereas no increase of the frequency of MN was found. The frequencies of chromatid type CA were 1.2, 3.91 and 9.67 per 500 cells in the controls, workers exposed to anticancer drug and workers exposed to EO, respectively. Lower frequency of CA in nurses handling anticancer drugs with safety covers compared to those without safety covers was observed, but it was not statistically significant. The frequency of CA in nurses handling anticancer drugs increased by the frequency of mixing anticancer drugs. Poisson regression analysis showed a significant association of the frequency of chromatid type CA with age, duration of wort exposure to anticancer drug and EO gas exposure, but no association of the frequency of chromosome type CA with any variables. The results suggested that there were associations between CA and the occupational exposure to low levels of anticancer drug and EO gas.

  • PDF

모래운반선의 창구덮개 면제를 위한 시설기준에 관한 연구 (A Study on the Release of Hatch Cover in Sand Carriers)

  • 정창현
    • 해양환경안전학회지
    • /
    • 제18권5호
    • /
    • pp.439-445
    • /
    • 2012
  • 모래운반선은 호퍼도어를 갖는 경우 제한된 범위내에서 창구덮개의 설치를 면제 받을 수 있으나, 현재 국내에는 호퍼도어를 갖고 있는 선박이 단 한척도 없어 창구덮개를 면제받는 선박이 없는 실정이다. 따라서 모래운반선의 창구덮개 관련 현행 규정의 검토와 사고사례 조사 그리고 현재 운항하고 있는 모래운반선에 대한 설비현황, 복원성능 및 내항성능 평가를 통하여 모래운반선에 대한 창구덮개 면제 조건을 검토하였다. 그 결과, 모래운반선의 경우 창구덮개를 면제 받기 위해서는 화물창의 크기를 조정하여 모래를 화물창 상단부까지 가득 싣더라도 흘수가 만재흘수선을 넘지 않도록 하고, 적절한 풍우밀 조치를 취함으로써 충분한 예비 부력과 복원력 확보가 요구된다. 또한, 배수펌프의 용량은 화물창의 액상상태인 모래를 1시간 이내에 소성상태가 될 수 있도록 배수하기에 충분한 용량이어야 하며, 모든 운항상태에서 작동 가능하여야 한다. 본 연구는 모래운반선의 작업 특성상 창구덮개의 설치작업이 현실적으로 상당히 어렵고, 특히 기상악화시 인명사고로 이어질 수 있는 현실적인 문제점을 항해안전과 관련된 시설기준을 보다 강화함으로써 개선한 것이다.

대구직할시(大邱直轄市) 두류공원(頭流公園) 도로조경계획(道路造景計劃) (Landscape Planning of Duryu Street Park in Taegu City)

  • 김용수;이현택
    • Current Research on Agriculture and Life Sciences
    • /
    • 제1권
    • /
    • pp.113-140
    • /
    • 1983
  • This is a study on a landscape planning along the street 1~4, which are gateways to Taegu city and an important scenery. Therefore, emphasis was given to provide a bright, clean and beautiful first impression to visitors and citizens. The area is being developed for education and athletic park. Plans to construct a fountain, pergolas and a pond were set up to complement the active and passive facilities to the existing a athletic facilities in the area. Since D part in the area have alkali soil (pH 8.1), soil amendment is necessary for successful growth of trees and ground covers. When the area is filled or added with new soil for soil amendment, it will be important to use fresh soil which can support plant growth. It will be ideal to use ground covers and shrubs on the existing retaining walls along the street for keeping natural vegetation and slope stability instead of further cutting and reconstruction. It is not reasonable in technical and economic sense to remove rocks of the slope for planting trees. In order to harmonize plant color distribute, tall needle and broad leaf trees in the background as a screen, flowering trees were arranged in groups at front, and annuals were mass-planted along the footway. Natural-form-trees will be planted because they not only serve as a greenbelt but also are more economics in maintenance than formative trees.

  • PDF

Alternative Energy - Environment Safety

  • Kurnaz, Sefer;Rustamov, Rustam B.;Zeynalov, Ismayil
    • International Journal of Aeronautical and Space Sciences
    • /
    • 제10권1호
    • /
    • pp.91-97
    • /
    • 2009
  • It is undertaken systematization of results of satellite and ground observation parameters characterizing a current condition and climatic variability of two selected geographical areas. One of them covers territory of Azerbaijan and another covers a wide area of Caspian See region. Average values and mean square deviations of following values are investigated: outgoing long wave radiation during a day and night (in nebulosity and cloudless). absorbed within a day of the stream of a sunlight of the system in "a terrestrial surface-atmosphere". degree of a covering by clouds of the selected areas during a day and at night, ground temperature values of air. pressure and speed of a wind. Monthly average values of corresponding parameters create a basis of suggested investigations. It has been presented features of a time course of investigated parameters for each month and year in the whole due to the continuously observations since 1982-2000. The scientific problem consists that there are no existed models which authentically would be cover the main aspects of a realities specified changes: they are identified by economic activities. growth of the population and other features of development of a human society or internal fluctuations of biogeophysical/climatic system. Possibilities of predictability of biosphere and climate changes depend on available timely supervision. adequacy of construction of appropriate models. understanding of mechanisms of direct and feedback influences in such complicated systems.

Analyzing Errors in Bilingual Multi-word Lexicons Automatically Constructed through a Pivot Language

  • Seo, Hyeong-Won;Kim, Jae-Hoon
    • Journal of Advanced Marine Engineering and Technology
    • /
    • 제39권2호
    • /
    • pp.172-178
    • /
    • 2015
  • Constructing a bilingual multi-word lexicon is confronted with many difficulties such as an absence of a commonly accepted gold-standard dataset. Besides, in fact, there is no everybody's definition of what a multi-word unit is. In considering these problems, this paper evaluates and analyzes the context vector approach which is one of a novel alignment method of constructing bilingual lexicons from parallel corpora, by comparing with one of general methods. The approach builds context vectors for both source and target single-word units from two parallel corpora. To adapt the approach to multi-word units, we identify all multi-word candidates (namely noun phrases in this work) first, and then concatenate them into single-word units. As a result, therefore, we can use the context vector approach to satisfy our need for multi-word units. In our experimental results, the context vector approach has shown stronger performance over the other approach. The contribution of the paper is analyzing the various types of errors for the experimental results. For the future works, we will study the similarity measure that not only covers a multi-word unit itself but also covers its constituents.

남성잡지Maxim 표지모델에 나타난 섹슈얼이미지에 관한 연구 (Study on Sexual Images on the Cover of Maxim Men's Magazine)

  • 김은정;곽태기
    • 복식
    • /
    • 제62권7호
    • /
    • pp.185-204
    • /
    • 2012
  • There are lots of sexual images in the contemporary media, and this is due to many of the media formats, such as television, magazines, and the Internet, using these images to relay various messages to the people. The media uses these sexual images (i.e. woman in a bikini) in order to use sex and eroticism as a marketing tool to the audience. Unlike other men's magazines, which actually have many female readers, Maxim magazine's readers are made of mostly men, and because of this, their magazine covers are usually filled with sexy women celebrities, such as singers or actors; images that can attract the general men. This study puts its focus on evaluating Maxim magazine's marketing strategy. The strategy of targeting men in their 20's and 30's, who were not interested in reading, but were impulsive and visually oriented. The study looked at magazine covers from November 2002 (the start of the magazine) to October 2008 (the peak period of its sales), and a total of 72 images were analyzed. For each image, 5 things were recorded (model's occupation, clothing style, hairstyle, makeup, pose and gaze).

프리기아[Phrygia] 모자에 대한 연구 (A Study on Phrygia Headgear)

  • 장영수
    • 복식
    • /
    • 제55권4호
    • /
    • pp.138-150
    • /
    • 2005
  • Phrygia headgear has an important meaning from the perspectives of costume history and cultural exchanges in ancient times. This study is to investigate the prototype of Phrygia headgear through analysis of its manufacturing methods and styles on the basis of prior studies on ancient sculptures and literatures conducted by European researchers and to examine its history and meanings. In these ways, this study will be helpful in understanding the importance of Phrygia headgear in cultural exchanges between the East and the West. Results of this study can be summarized as follows: Phrygia headgear was orn by eastern tribes, so it was a symbol of those from the east in ancient times. Phrygia headgear is frequently found in Greek artistic works of 5th to 4th century BC that depicted eastern tribes. Also, this headgear can be observed in artistic works for Mithras, Attis, or other gods. Since Phrygia headgear's shape is similar to that of Homer's helm, many researchers believe that it might be originated from Homer's helm. This headgear made of oxen scrotum(stierbeutel) or its surrounding skin has a long end at the top. This long end is round and drooping toward the front side. From such unique shape, we top. This long end is round and drooping toward the front side. From such unique shape, we top. This long end is round and drooping toward the front side. From such unique shape, we can draw a conclusion that Phrygia headgear was made of oxen scrotum and its surrounding skin. Dependingy on drooping patterns, there are various shapes, such as the round, tightly swollen one worn by Mithras, the tongue-shaped one found in Basilika S. Apolinare Nuovo's mosaic depicting three wise men, the balloon-shaped one frequently found in Greek vases depicting Scythian, and the one drooping to the side depicted in Alexandersarkophag. Further, some Phrygia headgear has covers for neck and ears. For example, Phrygia headgear worn by Persian Satrap tribe has such covers attached to the head part. Meanwhile, Phrygia headgear worn by Amazone tribe does not show such separate covers, Rather, one piece of oxen skin was tanned and finished to make such covers. Wearing Phrygia headgear can be interpreted in several ways. Use of animal's skin for wearing things is a unique aspect in ancient societies because they believed that wearing animal skin would give them power of the animal. Further, Phrygia headgear made of oxen scrotum was a symbol of reproductive power to women.