• Title, Summary, Keyword: Density

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Preparation of Low Density Ceramic Supporter from Coal Fly Ash

  • Yeon Hwang;Lee, Hyo-Sook;Lee, Woo-Chul
    • Proceedings of the IEEK Conference
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    • pp.605-609
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    • 2001
  • Low density ceramic supporter was prepared by using fly ash as a starting material for the application to the biological aerated filter (BAF) system, and the effect of additives and sintering atmosphere on the apparent and bulk density of the carrier was examined. Borax, Na$_2$O and glass powders were added to produce liquid phase. The density of the supporter decreased as the amount of borax increased. The bulk density of 0.79 g/㎤ and the apparent density of 1.10 g/㎤ were obtained when the fly ash with 15% of borax was sintered at 116$0^{\circ}C$ for 15 minutes. The density also decreased as the plate glass powders past through 22${\mu}{\textrm}{m}$ size were mixed. When the fly ash with 12% of grass powder was sintered at 128$0^{\circ}C$ for 10 minutes, the bulk and apparent density were 0.90g/㎤ and 1.00 g/㎤, respectively. Apparent density of 1.6~1.8g/㎤ was obtained when the fly ash was sintered at 120$0^{\circ}C$ in a weak reducing atmosphere. By maintaining the reducing atmosphere and sintering at a high heating rate, the liquid phase was farmed from the reduced composition of fly ash. This resulted in the formation of closed pores that enabled the low apparent density.

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Morphometric Study of Heart Development in Rat Fetus (Rat 태생기의 심장성장에 따른 형태측량적 연구)

  • Park, Won-Hark;Lee, Yong-Deok;Chung, Hyeung-Jae;Choi, Jeung-Mog
    • Applied Microscopy
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    • v.19 no.2
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    • pp.85-98
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    • 1989
  • The ventricular myocardia of 14, 16, 18 and 20-day-old rat fetuses and newborns have been studies by light and electron microscopic morphometrics. The volume density of the myocyte and interstitial compartments as well as volume, surface and numerical density of nuclei were estimated by light microscopic morphometrics. Whereas, the volume density of myofibrils and glycogen granules as well as the volume, surface and numerical density of mitochondria were assessed by electron microscopic morphometrics. The volume density of myocyte compartment of the ventricular myocardia in developing fetuses decreased, but increased in newborn rats. On the other hand, the volume density of the interstitial compartment increased in growing fetuses and decreased in newborns. In all groups the volume, surface and numerical density of nuclei decreased gradually with elongation of myocytes. Conversely, the volume, surface and numerical density of mitochondria and volume density of myofibrils and glycogen granules in ventricular myocytes incresed. The increase in numerical density of mitochondria probably reflects an increase in metabolic activity. Sarcomere length also increased during development.

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A Study on Interpretation of Gravity Data on Two-Dimensional Geologic Structures by Iterative Nonlinear Inverse (반복적 비선형역산에 의한 2차원 지질구조의 중력자료 해석 연구)

  • Ko, Chin-Surk;Yang, Seung-Jin
    • Economic and Environmental Geology
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    • v.27 no.5
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    • pp.479-489
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    • 1994
  • In this paper, the iterative least-squares inversion method is used to determine shapes and density contrasts of 2-D structures from the gravity data. The 2-D structures are represented by their cross-sections of N-sided polygons with density contrasts which are constant or varying with depth. Gravity data are calculated by theoretical formulas for the above structure models. The data are considered as observed ones and used for inversions. The inversions are performed by the following processes: I) polygon's vertices and density contrast are initially assumed, 2) gravity are calculated for the assumed model and error between the true (observed) and calculated gravity are determined, 3) new vertices and density contrast are determined from the error by using the damped least-squares inversion method, and 4) final model is determined when the error is very small. Results of this study show that the shape and density contrast of each model are accurately determined when the density contrast is constant or vertical density gradient is known. In case where the density gradient is unknown, the inversion gives incorrect results. But the shape and density gradient of the model are determined when the surface density contrast is known.

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Dietary calcium intake, physical activity, and bone mineral density in elderly men (노년기 남성의 칼슘 영양 상태, 육체적 활동량과 골격 대사에 관한 연구)

  • 이명희
    • Journal of the Korean Home Economics Association
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    • v.29 no.3
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    • pp.61-69
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    • 1991
  • The relationships between nutrients intake, physical activity and bone mineral density were investigated in 19 elderly men aged 71-80 years. A trained nutritionist interviewed usual dietary intake and daily activity with a questionnaire, and bone mineral density was measured at the lumbar spine and three regions of the proximal femur (femur neck, Ward's triangle and trochanter) with a Luna DP3 dual photon absorptiometry. The correlations between dietary calcium intake and bone mineral density at the lumbar spine and trochanteric region were significant at P<0.05 and P<0.01 level respectively. the significant correlations were also found between vitamin A(P<0.005), riboflavin(P<0.01), and ascorbic acid(P<0.05) intake and bone mineral density at these sites. Higher physical activity was associated with greater bone mineral density of four sites, but this was not significant. But there were significant relationships between total energy expenditure and bone mineral density of the lumbar spine(P<0.01), femur neck (P<0.05) and Ward's triangle(P<0.05). In this study the results revealed that bone mineral density of the lumbar spine and trochanteric region were associated with dietary calcium intake. And bone mineral density of the femur neck and Ward's triangle were related to physical activity but not to nutrients intake. In conclusion, dietary calcium intake seems to be a important factor for greater bone mineral density. Further evidence will be needed that physical activity protects against bone fracture and osteoporosis in the edlerly.

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Synthesis and Magnetic Properties of Electrodeposited Cobalt-Iron-Vanadium Thin Films

  • Chae, Kwang-Pyo
    • Journal of Magnetics
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    • v.11 no.2
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    • pp.87-89
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    • 2006
  • CoFeV thin film alloys were fabricated by electrodeposition, and the dependences of their magnetic properties on the current density were investigated using an X-ray diffractometer and a vibrating sample magnetometer. The deposited Co increased from about 45 to 60 wt.% with increasing current density until $25mA/cm^2$ whereas the deposited Fe decreased from about 55 to 40 wt.% with increasing current density until $25mA/cm^2$. The deposited V, about 2 wt.%, was independent of the current density. The current efficiencies of electrodeposition decreased linearly from about 40 to 29% with increasing current density. The X-ray diffraction measurement showed that all peaks of the CoFeV films were consistent with those of a typical Co hcp and Fe bcc mixed phase. An increase in the current density decreased the grain size and increased the lattice constant. The saturation magnetization increased from about 2.2 to 2.5 T with increasing current density. The coercivity measured in the perpendicular direction decreased from 260 to 120 Oe with increasing current density; a drastic drop of 60 Oe occurred at $5mA/cm^2$. The coercivity measured in the in-plane direction remained almost unchanged, at about 20 Oe, with increasing current density.

The bone density of mandible as the aging process in Koreans (한국인 연령에 따른 하악 치조골 골밀도)

  • Lee, Chul-Won;Kim, Chul-Hwan
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.37 no.6
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    • pp.496-504
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    • 2011
  • Introduction: This study compared the alveolar bone density of the mandible according to gender, age and position using Cone-beam computed tomography (CT). Materials and Methods: The maxillofacial CT scan data was obtained from 60 Korean patients. In addition, the alveloar bone density of 5 males and 5 females with normal occlusion aged from 10 to 70 years was measured at the buccal cortical bone, cancellous bone and lingual cortical bone, as well as at the position of the incisors, canines, premolars and molars. Results: The age-specific mean bone density was highest in patients in their third decade. The buccal cortical bone of the molars showed the highest bone density. Males in their fifties and sixties had a higher bone density in the cancellous bone in the region of the premolars and the buccal cortical bone of the molars, respectively, than females but there was no significant difference between males and females in the other parts. The cancellous bone density was highest in those in their twenties and thirties, and tended to decline up to their seventh decade. Conclusion: These results revealed a significantly different bone density according to gender, age and position in the Korean population. In addition, it is possible to predict the bone density based on these results.

Effects of Stocking Density on the Blind-side Hypermelanosis of Cultured Olive Flounder Paralichthys olivaceus

  • Kang, Duk-Young;Kim, Hyo-Chan;Chang, Young-Jin
    • Fisheries and aquatic sciences
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    • v.14 no.2
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    • pp.123-129
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    • 2011
  • To determine whether rearing density affects the hypermelanosis on the blind side (ambicoloration) of olive flounders Paralichthys olivaceus, we reared fry with an unpigmented non-eyed (blind) side in duplicate at densities of 150 individuals/$m^2$ (commercial production density: control) and 450 individuals/$m^2$ (high density group) for 90 days in 1-t dark-green fiberglass reinforced plastics (FRP) tank. We recorded feed intake, feed conversion efficiency (FE), growth and survival, and measured the ratios of staining blind-side area (staining area) and ambicolored fish every 30 days. Daily feed intake (DFI), feed conversion efficiency (FE), growth rate, condition factors, and survival rate were calculated at the end of the experiment. Although the FE was higher in the high-density compared to the control, the two density groups showed similar feed intakes, growth, and survival. The ratio of staining area as well as the ratio of ambicolored fish significantly were significantly higher in the high-density group than in the control from days 30 to 60, but significantly increased and evened out by the end of the experiment (P<0.05). In conclusion, we determined that rearing density is not the main cause of the blind-side hypermelanosis, but found that increasing the rearing density can accelerate the ambicoloration in olive flounders.

A simple analysis on the abnormal behavior of the argon metastable density in an inductively coupled Ar plasma

  • Park, Min;Yu, Sin-Jae;Kim, Jeong-Hyeong;Seong, Dae-Jin;Sin, Yong-Hyeon;Jang, Hong-Yeong
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.438-438
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    • 2010
  • The abnormal behavior of the argon metastable density during the E-H mode transition in argon ICP discharge was investigated. Lots of investigations including global models expected that during and after the mode transition of ICP discharge, the density of metastable increases with applied rf power (i.e. electron density). However, recent direct measurement of metastable density revealed that the metastable density of argon decreases with the applied power during and after the mode transition. This result may not be explained by the previous global model which is based on the assumption of the Maxwellian electron energy distribution function (EEDF). In this paper, to explain this abnormal behavior with simple manners, a simple global model taking account of the effect of the non-Maxwellian EEDFs incorporating into a set of coupled rate equations is proposed. The result showed that the calculated metastable density taking account of non-Maxwellian EEDF and its evolution during the transition has an abnormal behavior with electron density and is in good agreement with the previous measurement results, indicating the close coupling of electron kinetics and the behavior of metastable density. The proposed simple model is expected to provide qualitative kinetic insight to understand the behavior of the metastable density in various plasma discharges which typically exhibit non-Maxwellian distribution.

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Evaluation of Plasma Characteristics for Hg-Ar Using LIF (LIF를 이용한 Hg-Ar 플라즈마 특성 평가)

  • Moon, Jong-Dae
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.2
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    • pp.79-83
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    • 2008
  • In this paper, we introduced a LIF measurement method and summarized the theoretical side. When an altered wavelength of laser and electric power, lamp applied electric power, we measured the relative density of the metastable state in mercury after observing a laser induced fluorescence signal of 404.8nm and 546.2nm, and confirmed the horizontal distribution of plasma density in the discharge lamp. Due to this generation, the extinction of atoms in a metastable state occurred through collision, ionization, and excitation between plasma particles. The density and distribution of the metastable state depended on the energy and density of plasma particles, intensely. This highlights the importance of measuring density distribution in plasma electric discharge mechanism study. The results confirmed the resonance phenomenon regarding the energy level of atoms along a wavelength. change, and also confirmed that the largest fluorescent signal in 436nm, and that the density of atoms in 546.2nm ($6^3S_1{\to}6^3P_2$) were larger than 404.8nm ($6^3S_1{\to}6^3P_2$). According to the increase of lamp applied electric power, plasma density increased, too. When increased with laser electric power, the LIF signal reached a saturation state in more than 2.6mJ. When partial plasma density distribution along a horizontal axis was measured using the laser induced fluorescence method, the density decreased by recombination away from the center.

The evaluation of fabric on the Internet -The difference of cotton fabric texture perceived between on-line and off-line- (인터넷에서의 소재 평가에 대한 연구 -실물과 영상에서의 면직물 유사성 평가-)

  • 신혜원;이정순
    • Journal of the Korean Society of Clothing and Textiles
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    • v.28 no.3_4
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    • pp.396-402
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    • 2004
  • The purpose of this study was to investigate the difference of cotton fabric texture perceived between on-line(screening fabric) and off-line(real fabric), and to analyze fabric characteristics having an effect on the difference. The similarity of 55 various cotton fabrics perceived between on-line and on-line were measured showing simultaneously real fabrics and screening fabrics by 7-scale questionnaire. And the characteristics of cotton fabrics such as weave structure, thickness, weight, fabric density, stiffness, Hunter's L, a, b, and hue were measured. Cotton fabrics were classified into 3 groups by extent of similarity. There were no significant differences in weft density, stiffness, Hunter's L, a, b, and hue among 3 groups. But there were significant differences in weave structure, thickness, weight, warp density, and difference of warp & weft density. The fabrics having large similarity were thick and heavy, had small warp density and difference of warp & weft density, and distinct surface texture. The group having medium similarity included fabrics of medium thickness and weight, having weak surface texture, large warp density and difference of warp & weft density. The group having small similarity, which the differences between on-line and off-line were large, included thin and light fabrics having smooth surface and large warp density and difference of warp & weft density.