• 제목/요약/키워드: Densities

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잣나무 조림지내 토양미소절지동물상에 관한 연구. 3. 토양미소절지동물의 종류와 분포 (Soil microarthropods fauna in plantations of the Korean pine(Pinus koraiensis S. et Z.). 3. Population densities of soil microarthropods)

  • 권영립
    • 한국응용곤충학회지
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    • 제32권2호
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    • pp.168-175
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    • 1993
  • This study investigated the composition and distribution of the soil microarthropods community in plantations of the Korean pine(Pinus Koraiensis SIEB. et ZUCC, the sudong area, Namyangju-gun, Korea) , which had been planted in different years. The soil samples intended to collect soil animals were taken monthly from June 1988 to July 1989. The composition of soil microarthropods community included Arachnida, Chilopoda, Insecta, Collembola, Diplopoda, Crustacea, and Symphyla. The Acarina were composed of 82.4% of Cryptostigmata, 8.0% of Mesostigmata, 7.9% of nymphs, and 1.7% of others. The Insecta included six orders including Hymenoptera(65.8%) and Diptera(13.9%). Population densities increased from when the plantations were first established until the planting were 25 years old, after which they declined. Population densities of the soil microarthropods were highest in July and lowest in January. The Collembola/Acarina ratio is 0.16 overall, and was highest in January and lowest in August.

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Relations between tensile stresses and critical current densities of coated conductors

  • Yoo, Ja-Eun;Youm, Do-Jun
    • 한국초전도학회:학술대회논문집
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    • 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
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    • pp.136-139
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    • 2000
  • The relations between tensile stresses and critical current densities (J$_c$) of coated conductors were measured. Around 320 MPa of tensile stress, the critical current densities of coated conductor fabricated on pure Ni tape were reduced to zero at 77K, where J$_c$ for zero stress was order of 10$^5$A/cm. The critical tensile stress was much enhanced for the coated conductors fabricated on NiCr alloy tapes. However fabrication conditions for the growth on such alloys are much different from those on the pure Ni and it was not easy to get good textures and large critical currents. The detailed fabrication methods on those alloys will be presented.

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Coated conductor에서 magneto-optical image와 scanning hall probe를 이용한 flux profile의 측정 및 분석 (Measurement and Analysis of the Flux Profiles of the Coated Conductors using Magneto-optical Image and Scanning Hall Probe)

  • 이효연;곽기성;이준규;유재은;염도준
    • Progress in Superconductivity
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    • 제11권2호
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    • pp.128-134
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    • 2010
  • The magnetic flux profiles in SmBCO and YBCO coated conductors(CC) in the presence of the external field were comparatively investigated by magneto-optic image and scanning hall probe measurements. The current distributions calculated by using the inversion method from measured field profiles show that the decrease of current densities near the edges of SmBCO CC is more significant than those of YBCO CC. Through the comparison of the numerical analysis based on Kim's critical state model and the Brandt and Indenbom's solution, we found that this feature is related to their different field dependant properties of the critical current densities.

Investigating loading rate and fibre densities influence on SRG - concrete bond behaviour

  • Jahangir, Hashem;Esfahani, Mohammad Reza
    • Steel and Composite Structures
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    • 제34권6호
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    • pp.877-889
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    • 2020
  • This work features the outcomes of an empirical investigation into the characteristics of steel reinforced grout (SRG) composite - concrete interfaces. The parameters varied were loading rate, densities of steel fibres and types of load displacement responses or measurements (slip and machine grips). The following observations and results were derived from standard single-lap shear tests. Interfacial debonding of SRG - concrete joints is a function of both fracture of matrix along the bond interface and slippage of fibre. A change in the loading rate results in a variation in peak load (Pmax) and the correlative stress (σmax), slip and machine grips readings at measured peak load. Further analysis of load responses revealed that the behaviour of load responses is shaped by loading rate, fibre density as well as load response measurement variable. Notably, the out-of-plane displacement at peak load increased with increments in load rates and were independent of specimen fibre densities.

수직평판 사이를 흐르는 두 점성유체의 밀도차에 의한 계면의 새로운 불안정성 연구 (A study of a new interfacial instability between two vertical fluid layers of different densities)

  • 이철우;주상우;이상천
    • 대한기계학회논문집B
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    • 제20권12호
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    • pp.3949-3959
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    • 1996
  • A new interfacial instability between two vertical fluid layers of different densities is studied. The two layers are flowing between two parallel vertical plates vertically upward or downward, forming counter- or concurrent flows. In order to extend the study to highly-nonlinear regime in future studies, a nonlinear interface evolution equation is derived, and the stability analysis is performed based on the evolution equation. Among the parameters studies are the ratios of the fluid densities and layer thicknesses and the net flow rate.

Structure and Properties of Indium Tin Oxide Thin Films Sputtered from Different Target Densities

  • Kim Kyoo Ho;Jung Young Hee;Munir Badrul;Wibowo Rachmat Adhi
    • 한국표면공학회지
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    • 제38권5호
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    • pp.179-182
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    • 2005
  • Indium Tin Oxide (ITO) thin films were deposited from various target densities ($98.7\%\~99.6\%$) using RF magnetron sputtering. Effect of the sputtering target densities on the structural, electrical and optical properties of deposited ITO thin films was investigated. The preferable (400) crystalline orientation peak was observed on the films deposited from > $99.0\%$ target density. Higher target density produced films with higher roughness but lower resistivity. All of the deposited films showed optical transmittance more than $85\%$ in the visible wavelength region. It is necessary to use the highest target density for sputtering deposition of ITO thin films.

분말 가압 성형 공정 변수 최적화에 관한 연구 (Study on the Optimization of Powder Compaction Process Parameters)

  • 김정래;금영탁
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2005년도 추계학술대회 논문집
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    • pp.476-479
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    • 2005
  • In this study, the process parameters in powder compaction are optimized for getting high relative densities. To find optimized parameters, the analytic models of powder compaction are firstly prepared by 2-dimensional rod arrays with random green densities using a quasi-random multi-particle array. Then, using finite element method, the changes in relative densities are analyzed by varying the size of the particle, the amplitude of cyclic compaction, and the coefficient of friction, which influence the relative density in cyclic compactions. After the analytic function of relative density associated process parameters are formulated by aid of the response surface method, the optimal conditions in powder compaction process are found by the grid search method.

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The Influence of Radiation Trapping on the Metastable Population Density and Applications to Low-pressure Plasma

  • 이영광;오세진;정진욱
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2011년도 제40회 동계학술대회 초록집
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    • pp.245-246
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    • 2011
  • Emission lines ratios were used for diagnostics of and excited level densities in low-temperature plasmas. In this work, an optical emission spectroscopy (OES) was used to determine the electron temperature and metastable level densities in low-pressure inductively coupled plasma. The emission spectroscopy method was based on a simple collisional-radiative model. The selected lines of the Ar(4p to 4s) were influenced by the radiation trapping at relatively high pressures where the plasma become optically thick. To quantify this effect, a pressure dependence factor ${\alpha}$(P) was derived by using corrections for the measured intensities. It was found that the lower metastable level densities were obtained when ${\alpha}$(P) increased with the increasing discharge pressure. The effect of non-Maxwellian electron energy distribution functions (EEDFs) on the metastables was also presented and discussed.

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The Effects of Electron Beam Exposure Time on Transmission Electron Microscopy Imaging of Negatively Stained Biological Samples

  • Kim, Kyumin;Chung, Jeong Min;Lee, Sangmin;Jung, Hyun Suk
    • Applied Microscopy
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    • 제45권3호
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    • pp.150-154
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    • 2015
  • Negative staining electron microscopy facilitates the visualization of small bio-materials such as proteins; thus, many electron microscopists have used this conventional method to visualize the morphologies and structures of biological materials. To achieve sufficient contrast of the materials, a number of imaging parameters must be considered. Here, we examined the effects of one of the fundamental imaging parameters, electron beam exposure time, on electron densities generated using transmission electron microscopy. A single site of a negatively stained biological sample was illuminated with the electron beam for different times (1, 2, or 4 seconds) and sets of micrographs were collected. Computational image processing demonstrated that longer exposure times provide better electron densities at the molecular level. This report describes technical procedures for testing parameters that allow enhanced evaluations of the densities of electron microscopy images.

교류 아크용접기를 사용하는 작업자의 인체 유도전류밀도 해석 (Analyses on Current Densities Induced Inside a Worker Using AC Arc Welder)

  • 박준형;민석원
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2007년도 제38회 하계학술대회
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    • pp.1410-1411
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    • 2007
  • This paper analyses current densities induced inside a worker using AC arc welder. Applying the boundary element method, we calculate current densities induced in organs inside a worker in case he was located at 1[cm], 3[cm], 5[cm], 10[cm], 15[cm], 20[cm] far from a power cable of AC arc welder. As results of study, we find a maximum current density induces at a heart surface and may be higher than 10[$mA/m^2$] of ICNIRP guideline if he works within 15[cm] from a power cable.

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