• Title, Summary, Keyword: Density

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A Study on the Dimensional Characteristics of the Weft Knitted Fabrics with Bamboo Knitted Yarn (Bamboo사 평 편조직 위편성물의 형태안정성에 관한 연구)

  • Choi, Jae-Woo;Jang, Bong-Sik;Lee, Eun-Woo;Kim, Dong-Yeub
    • Journal of the Korean Society of Industry Convergence
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    • v.15 no.3
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    • pp.79-82
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    • 2012
  • Aim of this study is to investigate the dimensional characteristics of the weft knitted fabrics with Bamboo knitted yarn. This Bamboo knitted yarn was made of the biodegradability fiber. The structure of weft knitted fabrics that was utilized for this study is the plain stitch, which is the most basic structure among all weft knitted fabrics. The loop density, courses density, and wales density are more increased as the loop length is shorter. The loop density increased as pre-treatment process and dyeing process progressed after dry treatment process, and on the contrary, the heat setting process made it decreasing. After the dyeing process proceed, the loop density and the course density were displayed the highest values. When the knitted fabrics were fully relaxed, the loop density was $2000/in^2$, the courses density was 52/in, the wales density was 39/in.

Analysis of the Linear Density Behavior of Drawn Slivers. II. Effects of Draw Ratio and Roller Distance (연조 슬라이버의 선밀도 거동 해석. II. 연조비와 롤러 간격 효과)

  • Lim, Jung Ho;Kim, Jong S.;Huh, You
    • Textile Science and Engineering
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    • v.55 no.6
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    • pp.415-424
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    • 2018
  • The behavioral characteristics of sliver linear density under roller drafting operation were investigated in this study. A theoretical model describing the dynamic behavior of the staples flowing in a single direction was applied. While the model parameters remained constant, the process parameters including draw ratio and roller distance were varied. Simulations of the dynamic behavior of the drawn sliver linear density showed that it was dependent on the process conditions, and the effects varied depending on the staple length distribution. For uniform length staples, the linear density of the drawn sliver showed periodic changes at a steady state when the drawing roller distance was long. For the short drawing zone, the drawn sliver exhibited a constant steady state linear density. Increasing the draw ratio caused the linear density to change periodically which resulted in an increase in the CV% of the drawn sliver linear density. For length distributed staples, the linear density was sensitive to the draw ratio. At a low draw ratio, for example, DR=4, the drawing zone length did not affect the sliver linear density, and a constant linear density was observed. However, at high draw ratios, for example, DR=12, the drawing zone length affected the linear density behavior of the drawn sliver, showing periodic changes in the steady state. Thus, high draw ratios and long drawing zones caused a drastic increase in the CV% of the quasi-steady state linear density. In general, the two passes of sliver in a drawing operation with low draw ratio resulted in improved properties, that is, a more even linear density of the drawn sliver than that obtained using single drawing pass with a high level draw ratio, which drastically increased the linear density.

Theoretical Analysis of Magnetic Flux Density Distribution in an Electro-Magnetic Chuck

  • Kim, Chung-Kyun
    • KSTLE International Journal
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    • v.2 no.2
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    • pp.114-119
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    • 2001
  • The distribution of magnetic flux density of electro-magnetic chucks may clarify the clamping characteristics, which is strongly related to the machining efficiency and machining accuracy in surface grinding machine. Therefore the distribution of the normal and the tangential components of magnetic flux density have been analyzed theoretically. It appears that the normal component of magnetic flux density increases and the tangential component of magnetic flux density increases as the ratio of the separator width to the pitch, e/p decreases. The results seem to increase the stability and uniformity of normal component of magnetic flux density for the decreased e/p.

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A Support Vector Method for the Deconvolution Problem

  • Lee, Sung-Ho
    • Communications for Statistical Applications and Methods
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    • v.17 no.3
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    • pp.451-457
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    • 2010
  • This paper considers the problem of nonparametric deconvolution density estimation when sample observa-tions are contaminated by double exponentially distributed errors. Three different deconvolution density estima-tors are introduced: a weighted kernel density estimator, a kernel density estimator based on the support vector regression method in a RKHS, and a classical kernel density estimator. The performance of these deconvolution density estimators is compared by means of a simulation study.

A study on the Traffic Density Collect System using View Synthesis and Data Analysis (영상정합을 이용한 교통밀도 수집방법과 수집 데이터 비교분석)

  • Park, Bumjin;Roh, Chang-gyun
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.17 no.5
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    • pp.77-87
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    • 2018
  • Traffic Density is the most important of the three primary macroscopic traffic stream parameters, because it is most directly related to traffic demand(Traffic Engineering, 2004). It is defined as the number of existing vehicles within a given distance at a certain time. However, due to weather, road conditions, and cost issues, collecting density directly on the field is difficult. This makes studies of density less actively than those of traffic volume or velocity. For these reasons, there is insufficient attempts on divers collecting methods or researches on the accuracy of measured values. In this paper, we used the 'Density Measuring System' based on the synthesise technology of several camera images as a method to measure density. The collected density value by the 'Density Mesuring System' is selected as the true value based on the density define, and this value was compared with the density calculated by the traditional measurement methods. As a result of the comparison, the density value using the fundamental equation method is the closest to the true value as RMSE shows 1.8 to 2.5. In addition, we investigated some issues that can be overlooked easily such as the collecting interval to be considered on collecting density directly by calculating the moment density and the average density. Despite the actual traffic situation of the experiment site is LOS B, it is difficult to judge the real traffic situation because the moment density values per second are observed max 16.0 (veh/km) to min 2.0 (veh/km). However, the average density measured for 15 minutes at 30-second intervals was 8.3-7.9 (veh/km) and it indicates precisely LOS B.

Effect of Ensiling Density on Fermentation Quality of Guineagrass (Panicum maximum Jacq.) Silage during the Early Stage of Ensiling

  • Shao, Tao;Wang, T.;Shimojo, M.;Masuda, Y.
    • Asian-Australasian Journal of Animal Sciences
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    • v.18 no.9
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    • pp.1273-1278
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    • 2005
  • This study is to evaluate the effect of different levels of ensiling density on the fermentation quality of guineagrass silages during the early stage of ensiling. Guineagrass at the milky ripe stage was chopped and ensiled into a small-scale laboratory silo at two ensiling density levels (high density at 95 g/silo and low density at 75 g/silo). Three silos per level were opened after six ensiling periods (0.5, 1, 1.5, 2, 3 and 7 days of ensiling) and the fermentation qualities were analyzed. Within the initial 1.5 days of ensiling there were not significant (p>0.05) differences in the fermentation qualities between two density levels silages, and an almost constant pH and no or only small amounts of lactic acid, acetic acid and total volatile fatty acids were detected. However, the high density silage significantly (p<0.05) increased the rate and extent of fermentation after 1.5 days of ensiling, which was well reflected in significantly (p<0.05) faster and larger pH decline and lactic acid production at each elapsed time as compared with the low density silage. This resulted in significantly (p<0.05) lower finial pH and significantly (p<0.05) higher lactic acid content at the end of the experiment. Moreover, there was higher AA content relative to LA in both the H-D and L-D silages during the full fermentation course, and resulted in the AA-type silage. There were generally somewhat or significantly (p<0.05) higher acetic acid, volatile fatty acids and ammonia-N/total nitrogen in the high density silage than in the low density silage during the initial 3 days of ensiling. However, there were higher (p>0.05) ammonia-N/total nitrogen and significantly (p<0.05) higher butyric acid content in the low density silage at day 7 of ensiling. The silages of two density levels showed an initial increase in glucose between 0.5 and 1 day for the high density silage and between 1 and 1.5 days for the low density silage, respectively, thereafter showed a large decrease until the end of the experiment. There were not large differences (p>0.05) in ethanol content between the low density and high density silages that showed small amounts within initial 3 days of ensiling. However, the low density silage had a significantly (p<0.05) higher ethanol content than the high density silage at the end of experiment. From the above results it was suggested that the increase in ensiling density was an effective method to improve the fermentation quality, especially for tropical grasses.

Bone mineral Density of lumbar Spine in Children With Spastic Quadriplegia and Spastic Diplegia (경직성 사지마비와 양하지마비 아동의 요추부 골밀도)

  • Song, Ju-Young;Kim, Jin-Sang
    • Physical Therapy Korea
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    • v.8 no.1
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    • pp.51-58
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    • 2001
  • In children with cerebral palsy, bone density is decreased by disturbance of bone remodelling due to lack of normal weight bearing and muscle contraction through physical activity. Loss of bone density cause fracture, delays treatment with immobilization, and leads to functional limitation. The purpose of this study was to investigate bone mineral density of lumbar spine in children with spastic quadriplegia and diplegia. Six spastic quadriplegia and 14 spastic diplegia were evaluated in this study. QDR 4500 X-ray densitometer was used to measure bone density at lumbar spine (L1~L4). Children with cerebral palsy showed lower bone density than that of normal children. Bone density in children with spastic quadriplegia and diplegia was $-1.812{\pm}.962$, $-1.519{\pm}.935$, respectively. However, there was no significant differences in bone density between children with spastic quadriplegia and diplegia. There was no significant difference in bone density relation to motor development level, height, and weight. Further study is needed to find the appropriate interventions for preventing loss of bone density in children with cerebral palsy.

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The effectiveness of learning cycle approach to the construction of the concept of density and development of transformation ability of INRC group related to the concept of density (밀도개념과 밀도개념에 관련된 INRC 군 변환 능력의 형성에 미치는 순환학습의 효과)

  • Choi, Byung-Soon;Kim, Chung-Ho
    • Journal of The Korean Association For Science Education
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    • v.12 no.2
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    • pp.31-42
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    • 1992
  • The purposes of this study were to find out the degree of formation of the concept of density for the junior high students. The changing pattern of concept in acquiring the concept of density and the degree of development of INRC transformation ability related to the concept of density were also analyzed according to cognitive level and teaching method. The results of this study were as follows. 1) The experimental group were more effective than control group in the formation of the concept of density. 2) Even though students had been taught the concept of density, the various types of preconception were remained and persisted. Especially, the students at concrete level had persisted misconceptions and these misconceptions had been changed to the other misconceptions. 3) In the degree of the formation of the transformation ability of INRC group related to the concept of density in solid phase, the experimental group developed much better on both the abilities of Reciprocal transformation, Correlative transformation and the abilities to manipulate two variables such as volume and mass than control group. 4) The correlation coefficient between GALT score and achivement of the concept of density was 0.67. The correlation coefficient between achivement of the concept of density and the formation the transformation of INRC group related to the concept of density was 0.78.

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A Study on the Particles Density Estimation in Seoul Metropolitan (서울시 미세먼지의 밀도 추정에 관한 연구)

  • Kim, Shin-Do;Kim, Chang-Hwan;Hwang, Ui-Hyun
    • Journal of Environmental Health Sciences
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    • v.34 no.2
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    • pp.131-136
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    • 2008
  • The variation of the particle size distribution and density as well as the chemical composition of aerosols is important to evaluate the particles. This study measured and analyzed airborne particles using a scanning mobility particle sizer (SMPS) system and an aerodynamic particle sizer (APS) at the University of Seoul during every season. The highest particle number concentration of airborne particles less than $0.9\;{\mu}m$, occurred in winter, while the highest particle number concentration of airborne particles more than $0.9\;{\mu}m$, occurred in spring. Mass concentration appeared highest at spring. Also, when we compared $\beta$-ray's mass concentration with calculated mass concentration by using the SMPS-APS system during each season, density of the winter is $1.92\;g/cm^3$, spring density is $1.64\;g/cm^3$, fall density is $1.57\;g/cm^3$. We found out that PM10 density was differ every season. However, while the calculated density is whole density for PM10 the density of each diameter was different. In this study the density estimation equation of the QCM cascade impactor measured mass concentration of each diameter.

Sound Absorption and Physical Properties of Carbonized Fiberboards with Three Different Densities

  • Lee, Min;Park, Sang-Bum;Byeon, Hee-Seop
    • Journal of the Korean Wood Science and Technology
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    • v.42 no.5
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    • pp.555-562
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    • 2014
  • Characteristics of carbonized fiberboard such as chemical materials absorption, electromagnetic shielding, and electrical and mechanical performance were determined in previous studies. The carbonized board therefore confirmed that having excellent abilities of these characteristics. In this study, the effect of density on physical properties and sound absorption properties of carbonized fiberboards at $800^{\circ}C$ were investigated for the potential use of carbonized fiberboards as a replacement of conventional sound absorbing material. The thickness of fiberboards after carbonization was reduced 49.9%, 40.7%, and 43.3% in low density fiberboard (LDF), medium density fiberboard (MDF), and high density fiberboard (HDF), respectively. Based on SEM images, porosity of carbonized fiberboard increased by carbonization due to removing adhesives. Moreover, carbonization did not destroy structure of wood fiber based on SEM results. Carbonization process influenced contraction of fiberboard. The sound absorption coefficient of carbonized low density fiberboard (c-LDF) was higher than those of carbonized medium density fiberboard (c-MDF) and carbonized high density fiberboard (c-HDF). This result was similar with original fiberboards, which indicated sound absorbing ability was not significantly changed by carbonization compared to that of original fiberboards. Therefore, the sound absorbing coefficient may depend on source, texture, and density of fiberboard rather than carbonization.