• 제목/요약/키워드: average density

검색결과 2,457건 처리시간 0.032초

Environmental Dependence of Star Formation and HI Gas Fraction of Galaxies in the SDSS DR8

  • Jung, Su-Jin;Shim, Hyunjin
    • 천문학회보
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    • 제39권1호
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    • pp.47.1-47.1
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    • 2014
  • We examine the effect of environment on star formation activity of a sample of galaxy group catalogue given in Tempel et al.(2012) constructed from the Sloan Digital Sky Survey Data Release 8. In order to compare galaxies in different environment, we classify galaxies into two groups: galaxies in low density environment and galaxies in high density environment. After matching colors and apparent magnitudes of the galaxies, we are left with 5912 galaxies in each of the environment category. The fraction of star-forming galaxies in low-density environment is ~34%, higher than ~15% in high-density environment. Star-forming galaxies in low density environment have a higher average SFR value than those in high density environment. The bulge-to-disk ratio for galaxies in two different environment shows bimodal distribution. Regardless of the environment, we find galaxies with high star formation rate despite their red (g-r) color, for which the origin enhancing their star formation rate is investigated.

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Feasibility of Fabricating Variable Density Phantoms Using 3D Printing for Quality Assurance (QA) in Radiotherapy

  • Oh, Se An;Kim, Min Jeong;Kang, Ji Su;Hwang, Hyeon Seok;Kim, Young Jin;Kim, Seong Hoon;Park, Jae Won;Yea, Ji Woon;Kim, Sung Kyu
    • 한국의학물리학회지:의학물리
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    • 제28권3호
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    • pp.106-110
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    • 2017
  • The variable density phantom fabricated with varying the infill values of 3D printer to provide more accurate dose verification of radiation treatments. A total of 20 samples of rectangular shape were fabricated by using the $Finebot^{TM}$ (AnyWorks; Korea) Z420 model ($width{\times}length{\times}height=50mm{\times}50mm{\times}10mm$) varying the infill value from 5% to 100%. The samples were scanned with 1-mm thickness using a Philips Big Bore Brilliance CT Scanner (Philips Medical, Eindhoven, Netherlands). The average Hounsfield Unit (HU) measured by the region of interest (ROI) on the transversal CT images. The average HU and the infill values of the 3D printer measured through the 2D area profile measurement method exhibited a strong linear relationship (adjusted R-square=0.99563) in which the average HU changed from -926.8 to 36.7, while the infill values varied from 5% to 100%. This study showed the feasibility fabricating variable density phantoms using the 3D printer with FDM (Fused Deposition Modeling)-type and PLA (Poly Lactic Acid) materials.

중국 Changzhou댐의 방수로 운용에 따른 어류밀도와 분포에 관한 음향조사 (A Hydroacoustic Survey Analyzing Fish Populations and Their Distribution Upstream and Downstream of Changzhou Dam, China, Based on Spillway Conditions)

  • ;강명희
    • 한국수산과학회지
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    • 제44권4호
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    • pp.403-412
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    • 2011
  • Hydroacoustic surveys were performed to clarify the density and spatial distribution of fish upstream and downstream of Changzhou Dam in the Pearl River, China, with regard to the condition of the spillways. Fish were densely distributed in the forebay of the upstream dam and the average fish density was 0.22 individuals/$m^3$ under open spillways on 24 June 2010, but when the spillways were closed on 25 June 2010, the fish in the upstream dam dispersed and the average fish density decreased to 0.007 individuals/$m^3$. Meanwhile, the average fish density in the downstream region was 0.28 individuals/$m^3$ before the spillway was opened on 24 May 2010, but it decreased to 0.08 individuals/$m^3$ on 26 June, just after the spillway was closed. The vertical distribution of fish upstream of the dam was not consistent. The target strength (TS) of fish upstream of the dam was larger than that of fish in the downstream region, although the distribution of TS was similar between the upstream and downstream regions. Therefore, we concluded that while numerous fish could swim to the upstream region while the spillways were open, closed spillways obstructed fish migrating upward from the downstream region.

화자인식에서 연속밀도 은닉마코프모델의 혼합밀도 결정방법 (Gaussian Density Selection Method of CDHMM in Speaker Recognition)

  • 서창우;이주헌;임재열;이기용
    • 한국음향학회지
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    • 제22권8호
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    • pp.711-716
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    • 2003
  • 본 논문은 연속밀도 은닉마코프모델에서 각 상태별 혼합성분 개수를 결정하는 방법을 제안한다. 지금까지의 대부분의 연구가 연속밀도 은닉마코프모델에서 화자의 스펙트럼 특성에 상관없이 각 상태별 동일한 혼합성분 개수를 적용하였다. 이런 접근방법은 많은 계산량을 요구할 뿐만 아니라, 각 상태의 특성을 무시하고 있기 때문에 각 상태별 음성신호의 정확한 모델링을 할 수 없다. 따라서 본 논문에서 제안한 연속밀도 은닉마코프모델의 파라미터 추정은 각 상태별 혼합성분에 대한 발생 확률값에 따라서 결정하였다. 또한 혼합성분의 개수를 줄이는 과정에서 신호의 상관성을 줄이고 시스템의 전체적인 안정성을 얻기 위해서 주성분 분석을 이용하였다. 제안한 방법은 기존의 은닉마코프모델에 비해서 평균 10% 작은 혼합성분 개수를 이용했을 때를 기준으로 실험하였다. 실험결과에서 혼합성분 결정만을 적용했을 때 거의 비슷한 성능을 얻을 수 있었다. 그리고 주성분 분석을 이용했을 때, 특정벡터가 16 차일 때 평균 0.35%의 성능감소가 일어났지만, 25 차에서는 평균 0.65%의 성능개선을 얻을 수 있었다.

폐경 후 여성들의 골밀도와 신체 측정치 및 모성 요인과의 관련성 연구 -충남 일부 지역을 중심으로- (Bone Mineral Density, with Anthropometric Measurement, and Maternal Factors for Postmenopausal Women in Chungnam)

  • 박미자
    • 한국식품영양학회지
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    • 제20권4호
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    • pp.450-459
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    • 2007
  • This study was performed to assess the relationships between bone mineral density(BMD), anthropometric measurements, and maternal factors in postmenopausal women. The anthropometric measurements were taken by a trained practitioner, and the maternal factors of the 85 subjects in Chungnam were acquired by an interview questionaire. The BMDs of the lumbar $spines(L_2-L_4)$, femoral necks(FN), ward's triangles(WT), and trochanters(TR) were measured by dual energy X-ray absorptiometry(DEXA). The BMDs(T-score) for $L_2-L_4$, FN, and WT were 0.996 $g/cm^2$(-1.601), 0.697 $g/cm^2(-1.657)$, and 0.793 $g/cm^2(-1.512)$ respectively, which were assessed as osteopenia by the T-score ; TR was noma1 at 0.718 $g/cm^2(-0.675)$. The 85 subjects in Chungnam were divided into three groups according to their BMD measurements for $L_2-L_4$ and FN, assessed by the T-score. The percentages in the osteoporosis, osteopenia, and normal groups were 32.9%, 42.4, and 24.7%, respectively. The average age was significantly the highest in the osteoporosis group than in the other two osteopenia and normal group(p<0.001). The subjects' BMDs were positively correlated with weight, height, BMI, waist, WHR, OBR and hip circumference, and negatively correlated with the age, duration time after menopause, lactation, the age of last delivery, menarche age, and number of children. The average age at menopause was 48.8. The osteoporosis group's average age at menopause was lower than those of the other groups. However, the BMD of the lumbar spine positively correlated with duration time after menopause and the BMD of the femoral neck with lactation, last delivery, menarch age, number of children. Therefore, researches are needed to find out the effective way to minimize the effect of age and other physiological conditions on the decrease of bone mass density.

경북(慶北) 울진군(蔚珍郡) 폐흡충(肺吸蟲) 제2중간숙주(第2中間宿主)에서의 피낭유충(被囊幼蟲) 기생상(寄生狀) (Infestation status of Paragonimus westermani metacercariae in the second intermediate host in Ulchin county, Kyungpook Province)

  • 홍영애;주종윤;편영식
    • Parasites, Hosts and Diseases
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    • 제24권2호
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    • pp.194-200
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    • 1986
  • 1986년 5월부터 동년 10월까지 폐흡충 침윤지로 알려진 경북 울진군을 관류하는 남대천, 광천, 왕피천에서 가재의 분포상을 조사한 다음 가재에서의 폐흡충 피낭유충 기생상을 조사하였다. 가재의 서식밀도는 한사람이 한시간에 잡을수 있는 가재의 평균수로 표시하였으며, 이번 조사에서는 최소 1마리, 최고 13마리, 평균 4마리를 채집 할 수 있었다. 가재에서의 폐흡충 피낭유충 검출률은 총 피검가재 817마리중 127마리 (15.5%)였으며, 지역별로는 두천계곡에서 25.1%로 가장 높았다. 가재 체부위별 검출상은 감염가재 127마리에서 총 219개의 피낭유충을 검출하였으며, 이중 두흉부(60.7%), 아가미(37.4%), 간(1.8%)순으로 검출 할 수 있었으며, 감염가재 1마리당 평균 유출수는 1.7개 이었다. 이상의 성적으로 미루어 보아 경북 울진군 남대천, 광천, 왕피천 유역은 아직도 폐흡충 침윤지로 남아 있음을 알았다.

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여대생의 골밀도에 따른 식행동과 영양소 섭취상태 비교연구 (Comparative Study of Food Behaviors and Nutrients Intake according to the Bone Mineral Density of Female University Students)

  • 홍명선;박희옥;손춘영
    • 한국식품영양학회지
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    • 제25권1호
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    • pp.156-162
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    • 2012
  • The purpose of this study was to investigate the effect and correlation of anthropometric data, eating behaviors, and nutrient intake on the bone mineral density(BMD) of female college students. 349 female college students were surveyed and their age, height, and weight were an average of 20.5 years, 163.2 cm and 54.0 kg, respectively. Their average BMI was 20.2, with 66% falling in the normal range, 21.8% classified as underweight, 8.0% as overweight, and obese individuals comprised 3.4% of the sample by BMI classification. Calcaneal BMD was measured and the average T-score was 0.117. The results of BMD measurements were normal in 268 people(76.8%), osteopenia was found in 71 individuals(20.3%), and osteoporosis in 10(2.9%), respectively. There was a significant difference in bone mineral density according to height(p<0.05) and BMI (p<0.01). There were significant differences between BMD and eating behavior, regularity of eating behaviors(p<0.05), instant food intake(p<0.05), eating out(p<0.05) and nutritional supplement intake(p<0.05). In addition, normal the group with normal BMD had a more desirable eating behavior compared to the osteopenia and osteoporosis afflicted groups. BMD had a significant difference according to the nutrient intake of calcium(p<0.05), vitamin A(p<0.05), and vitamin C(p<0.05). In conclusion, BMD showed a good correlation with height(p<0.01), BMI(p<0.01), body composition including total body water(p<0.05), FFM(p<0.05), body protein(p<0.05) and intake of calcium(p<0.05), iron(p<0.05), vitamin A(p<0.05), and vitamin C(p<0.05). Therefore, an education plan and training on balanced diets proper body weight control, and desirable eating behaviors for female college students will be needed.

Dynamic failure features and brittleness evaluation of coal under different confining pressure

  • Liu, Xiaohui;Zheng, Yu;Hao, Qijun;Zhao, Rui;Xue, Yang;Zhang, Zhaopeng
    • Geomechanics and Engineering
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    • 제30권5호
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    • pp.401-411
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    • 2022
  • To obtain the dynamic mechanical properties, fracture modes, energy and brittleness characteristics of Furong Baijiao coal rock, the dynamic impact compression tests under 0, 4, 8 and 12 MPa confining pressure were carried out using the split Hopkinson pressure bar. The results show that failure mode of coal rock in uniaxial state is axial splitting failure, while it is mainly compression-shear failure with tensile failure in triaxial state. With strain rate and confining pressure increasing, compressive strength and peak strain increase, average fragmentation increases and fractal dimension decreases. Based on energy dissipation theory, the dissipated energy density of coal rock increases gradually with growing confining pressure, but it has little correlation with strain rate. Considering progressive destruction process of coal rock, damage variable was defined as the ratio of dissipated energy density to total absorbed energy density. The maximum damage rate was obtained by deriving damage variable to reflect its maximum failure severity, then a brittleness index BD was established based on the maximum damage rate. BD value declined gradually as confining pressure and strain rate increase, indicating the decrease of brittleness and destruction degree. When confining pressure rises to 12 MPa, brittleness index and average fragmentation gradually stabilize, which shows confining pressure growing cannot cause continuous damage. Finally, integrating dynamic deformation and destruction process of coal rock and according to its final failure characteristics under different confining pressures, BD value is used to classify the brittleness into four grades.

고에너지 수준의 사료급여가 돈육 품질에 미치는 영향 (Effects of High Energy Density Diet on Pork Quality)

  • 이제룡;하승호;도창희;이중동;하영주;정재두;이진우;이정일;이진희
    • 한국축산식품학회지
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    • 제24권3호
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    • pp.209-215
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    • 2004
  • 본 시험은 고에너지 수준의 사료를 급여한 돼지의 사양성적, 돈육의 도체 특성, 일반성분, 이화학적 특성 및 지방산 조성에 미치는 영향을 조사하기 위해 실시하였다. 80$\pm$3 kg의 삼원교잡종 120두를 공시하여 비육돈 사료 변화의 영양소 수준에 따라 저에너지 DE 3,290 kcal/kg, CP 14.5%, Lysine 0.70%, Ca 0.78로 배합한 사료를 38일간 급여하였고, 고에너지 DE 3,350 kcal/kg, CP 15.0%, Lysine 0.10%, Ca 0.78%로 배합한 사료를 27일간 급여하였다. 저에너지와 고에너지 사료를 급여한 돼지의 종료체중이 101 kg내외에 도달했을 때 도축하여 시험에 공시하였다. 고에너지 사료를 급여한 돼지가 일당 증체량이 높았고, 사료섭취량과 사료요구율은 낮았다(p<0.05). 도체특성과 일반성분은 차이를 보이지 않았다 이화학적 특성 중 고에너지 사료를 급여한 돈육의 가열 감량과 황색도는 저에너지 사료를 급여한 돈육에 비해 현저히 높게 나타내었다(p<0.05). 지방산 조성에서는 저에너지와 고예너지 사료를 급여한 돈육에서 차이를 보이지 않았다. 이상에서 고에너지 사료를 27일간 급여한 돼지는 저에너지 사료를 38일간 급여한 돼지에 비해 성장률이 향상되었고, 돼지의 도체 특성, 물리적 특성 및 지방산 조성에는 미치지 않았지만 돈육의 가열 감량과 황색도가 높았다.

반복하중을 받는 해양실트질 모래의 상대밀도에 따른 응력기반 파괴기준 (Relative Density and Stress-Dependent Failure Criteria of Marine Silty Sand Subjected to Cyclic Loading)

  • 고민재;손수원;김진만
    • 한국지반공학회논문집
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    • 제33권1호
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    • pp.79-91
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    • 2017
  • 반복단순전단시험기를 이용하여 해양실트질 모래의 상대밀도 변화에 따른 비배수전단파괴 거동에 대해 평균전단응력과 반복전단응력이 미치는 영향을 평가하였다. 시험결과 반복전단 변형모드는 상대밀도가 달라지더라도 유사한 양상을 보였으며, 평균전단응력과 반복전단응력으로부터 큰 영향을 받았다. 파괴에 필요한 반복하중 횟수는 반복전단응력비, 상대밀도, 그리고 평균전단응력비의 순서로 좌우되는 것으로 나타났다. 본 논문에서는 조밀한 지반과 느슨한 지반에서 상대밀도 변화에 따른 응력기반 파괴경로의 변화를 2차원과 3차원으로 제시하였으며, 3차원 파괴선도는 조밀한 지반 조건에 대해서만 한정된 한계점을 보완하여 지반의 상대밀도에 따라 반복전단응력비, 평균전단응력비, 반복하중 횟수 등의 설계 조건을 결정 할 수 있는 아주 유용한 설계도구로 활용 가능하다.