• Title, Summary, Keyword: Density

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Understanding DFT Calculations of Weak Interactions: Density-Corrected Density Functional Theory

  • Park, Hansol;Kim, Yeil;Sim, Eunji
    • Journal of the Korean Chemical Society
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    • v.63 no.1
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    • pp.24-28
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    • 2019
  • In this work, we discuss where the failure of Kohn-Sham Density Functional Theory (DFT) occurs in weak interactions. We have adopted density-corrected density functional calculations and dispersion correction separately to find out whether the failure is due to density-driven error or functional error. The results of Benzene Ar complex, one of the most common examples of van der Waals interactions, show that DFT calculations of van der Waals interaction suffer from functional error, rather than density-driven error. In addition, errors in DFT calculations of the S22 dataset, which contains small to relatively large (30 atoms) complexes with non-covalent interactions, are governed by functional errors.

A Spray Characteristics of Dual Orifice Injector with Different Fuel Properties (연료 종류에 따른 이중 오리피스 노즐의 분무 특성 연구)

  • Lee, D.H.;Choi, S.M.;Park, J.B.
    • Journal of ILASS-Korea
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    • v.8 no.2
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    • pp.7-15
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    • 2003
  • The effects of fuel density and fuel viscosity on spray characteristics were investigated under two different gas turbine fuels and various fuel supply pressure conditions through measurement of SMD, number density and volume flux by using PDPA system in dual orifice injector for gas turbine engines. In this study, we found out that the droplet size and spray structure are strongly depend on fuel density for dual orifice injector. The spray characteristics of high density fuel in dual orifice injector are similar with the characteristics of low density fuel in single orifice injector. The shear region between primary main fuel stream and secondary main fuel stream is examined in low density fuel condition but not exist in high density fuel condition, then this shear region is very important in quality of gas turbine spray. There are worth consideration for the effect of fuel density on spray characteristics in frontal device design to improve combustion efficiency.

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Effects of Canopy and Settlement Density on the Performance of the Brown Seaweed Fucus serratus Germlings

  • Choi, Han-Gil
    • Animal cells and systems
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    • v.7 no.4
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    • pp.295-301
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    • 2003
  • Effects of the settlement density of germlings and canopy on settled germlings of Fucus serratus were investigated on the rocky shore of the Isle of Man. The survival of transplanted germlings was mainly determined by parent canopy rather than by initial settlement density of germlings. However, germling growth was greater at low density than at high density and enhanced by canopy removal. Recruitment by natural propagules was stimulated at high settlement density and maximal recruits occurred on caged slides under the canopy. On the experimental slides, tiny snails and sedimentation were ,found. The number of snails was positively related with the settlement density of germ lings indicating that they fed the germlings. Sedimentation and snail number were greater with canopy removal treatments than in canopy intact ones. These indicate that ,canopy sweeping gives benefits to germlings by removing sediment from substrata and protecting them from herbivores. In conclusion, the survival of settled F. serratus germlings is mainly determined by canopy sweeping and their growth is retarded in the presence of a canopy and at high settlement density.

Development of a Stand Density Management Diagram for Teak Forests in Southern India

  • Tewari, Vindhya Prasad;Alvarez-Gonz, Juan Gabriel
    • Journal of Forest and Environmental Science
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    • v.30 no.3
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    • pp.259-266
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    • 2014
  • Stand Density Diagrams (SDD) are average stand-level models which graphically illustrate the relationship between yield, density and mortality throughout the various stages of forest development. These are useful tools for designing, displaying and evaluating alternative density regimes in even-aged forest ecosystems to achieve a desired future condition. This contribution presents an example of a SDD that has been constructed for teak forests of Karnataka in southern India. The relationship between stand density, dominant height, quadratic mean diameter, relative spacing and stand volume is represented in one graph. The relative spacing index was used to characterize the population density. Two equations were fitted simultaneously to the data collected from 27 sample plots measured annually for three years: one relates quadratic mean diameter with stand density and dominant height while the other relates total stand volume with quadratic mean diameter, stand density and dominant height.

Characteristics of Solar Wind Density Depletions During Solar Cycles 23 and 24

  • Park, Keunchan;Lee, Jeongwoo;Yi, Yu;Lee, Jaejin;Sohn, Jongdae
    • Journal of Astronomy and Space Sciences
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    • v.34 no.2
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    • pp.105-110
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    • 2017
  • Solar wind density depletions are phenomena that solar wind density is rapidly decreased and keep the state. They are generally believed to be caused by the interplanetary (IP) shocks. However, there are other cases that are hardly associated with IP shocks. We set up a hypothesis for this phenomenon and analyze this study. We have collected the solar wind parameters such as density, speed and interplanetary magnetic field (IMF) data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the advanced composition explorer (ACE) and the Wind satellite. We also calculate two pressures (magnetic, dynamic) and analyze the relation with density depletion. As a result, we found total 53 events and the most these phenomena's sources caused by IP shock are interplanetary coronal mass ejection (ICME). We also found that solar wind density depletions are scarcely related with IP shock's parameters. The solar wind density is correlated with solar wind dynamic pressure within density depletion. However, the solar wind density has an little anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. Additionally, In 47 events of IP shocks, we find 6 events that show a feature of blast wave. The quantities of IP shocks are weaker than blast wave from the Sun, they are declined in a short time after increasing rapidly. We thus argue that IMF strength or dynamic pressure are an important factor in understanding the nature of solar wind density depletion. Since IMF strength and solar wind speed varies with solar cycle, we will also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an additional clue to their physical nature.

Structure Factor와 Electron Density간의 관계

  • 서일환
    • Korean Journal of Crystallography
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    • v.11 no.4
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    • pp.241-246
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    • 2000
  • Structure factor는 위치를 포함한 electron density를 알면 계산되고 역으로 electron density는 phase를 포함한 structure factor를 알면 작도할수 있으므로 structure factor와 electron density는 서로 Fourier transform이다.

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A Clinical Study on the correlation between Bone Mineral Density (BMD) and Obesity in 480 normal adults (성인남녀 480명에서의 골밀도와 비만의 상관관계에 관한 임상적 연구)

  • Jang Soo-Jin;Kim Jeoung-Yeun;Yook Tae-Han
    • Journal of Acupuncture Research
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    • v.15 no.2
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    • pp.383-392
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    • 1998
  • Osteoporosis is the most common metabolic disease of the bone, and constitutes one of the most important major pubulic health problems world wide. Therefore, in order to be helped early diagnosis, treatment and prevention of osteoporosis, measurement of Bone Mineral Density (BMD) is to be needed. Authors has analysed Bone Mineral Density (BMD) of 480 normal adults who visited woo suk unoversity Oriental Meclical Center from April 1998 to July 1998. The aims of this study is to investigate correlation between Bone Mineral Density (BMD) and age distribution, to examine the correlation between Bone Mineral Density (BMD) and Obesity. The results were as follows. 1. In distribution of age, the peak bone density of lumbar spine was noted around 30 years, and the peak bone density of the femoral neck was noted around 20 years. The age related loss of bone density follows soon after peak density. And the signifficant difference was revealed between lumbar spine and femoral neck bone density (p<0.001) 2. In distribution of sex, the bone density in male was signifficantly higher than in female (p<0.001). 3. In the correlation between Bone Mineral Density (BMD) and Obesity, Bone Mineral Density (BMD) in obese group was signifficantly higher than in non-obese group. Especially, in female from 50 up to 69 years, BMD had a positive correlation with Body mass index(BMI).

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Effects of Underground Empty Spaces on the Geomagnetic Flux Density Distribution (지하의 빈 공간에 의한 지자기의 자속밀도분포)

  • Lee, Moon-Ho
    • Journal of the Korean Magnetics Society
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    • v.19 no.2
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    • pp.67-73
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    • 2009
  • The changes of geomagnetic flux density distribution on the ground surface by underground empty spaces had been investigated through the variations of the soil density and measuring heights. The geomagnetic flux density distributions were monitored for the surfaces of different density, sink-hole and tunnel by fluxgate-type magnetometer. The underground empty space and low soil density decreased the geomagnetic flux densities, which were decreased from the boundary of raw and low-density (empty) grounds, and showed the lowest value at the center of low-density (empty) ground. The decreases of geomagnetic flux density by underground empty spaces could be found at the surface with the tunnel located at 80 m underground. And, the underground defects of empty spaces, low density zone, fracture zone and sink holes could be monitored by the phenomena of this decreasing flux density.

Bone Density of the Middle Aged Women Residing in Urban Area and the Related Factors -I. Distribution of Bone Density According to Age and the Prevalence of Osteoporosis in the Middle Aged Women Residing in Urban Area- (도시에 거주하는 중년여성들의 골밀도와 이에 영향을 미치는 인자들에 관한 연구 -I. 도시에 거주하는 중년여성들의 나이에 따른 골밀도 분포와 골다공증 이환율에 관한 연구-)

  • 손숙미;이윤나
    • Korean Journal of Community Nutrition
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    • v.3 no.3
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    • pp.380-388
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    • 1998
  • This study was conducted to investigate the distribution of bone density according to age and the prevalence rate of osteoporosis I 613, middle-aged women who visited Saint Bundo Hospital in Pusan from June to December, 1997. Mean bone density of lumbar spine(L2L4), and femoral neck of 50-59 years of age was significantly lower than those of 40-49 years of age(p<0.05). At the 60years of age, mean bone density of two sites were less than those of 50-59 years of age. Mean bone density of lumbar spine tin the group of sixties were 20.7% lower than that of group aged under 40 ; For femoral neck, women in their sixties showed 22.6% lower density compared to the women aged under forty. Bone density of ward's triangle of sixties were the least, which was 34.2% lower than that of group aged under 40. Bone density in lumbar spine, femoral neck, trochanter and ward's triangle correlates strongly with each other(p<0.001). The proportion of osteoporosis was 3.6% in the group of forties, 10.9% in the group of fifties and 33.8% for the group aged over 60, which was assessed by bone density of lumbar spine. Bone density of lumbar spine, femoral neck and ward's triangle were positively correlated with height, weight and BMI(p<0.001∼p<0.01), and weight showed highest correlation with the bone density. Forty-four percent of variation in lumbar spine bone density was explained by age and weight.

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Bayes Prediction Density in Linear Models

  • Kim, S.H.
    • Communications for Statistical Applications and Methods
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    • v.8 no.3
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    • pp.797-803
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    • 2001
  • This paper obtained Bayes prediction density for the spatial linear model with non-informative prior. It showed the results that predictive inferences is completely unaffected by departures from the normality assumption in the direction of the elliptical family and the structure of prediction density is unchanged by more than one additional future observations.

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