• Title, Summary, Keyword: Density

Search Result 34,488, Processing Time 0.086 seconds

Distributions of the Magnetic Flux Density Near Down-Conductors Due to Various Impulse Currents (임펄스전류에 의한 인하도선 주위에서 자속밀도의 분포)

  • 이복희;장근철;이수봉;강성만;이승칠
    • The Transactions of the Korean Institute of Electrical Engineers C
    • /
    • v.53 no.2
    • /
    • pp.109-115
    • /
    • 2004
  • This paper deals with the behaviors of magnetic flux density near down-conductors by lightning currents. The background on the principle of magnetic flux density measurements using the RL self-integrating magnetic field sensor was described. The magnetic flux density measuring device consisting of RL self-integrating magnetic field sensor and differential amplifier was designed and fabricated. The frequency bandwidth of the magnetic flux density measuring system ranges from 200 Hz to 300 KHz and the response sensitivity was 0.126 $\mu$T/㎷ The distributions of the magnetic flux density near down-conductors due to impulse currents with various rise times were analyzed as a parameter of the bonding conditions and materials of conductor and wiring conduits. The magnetic flux density due to impulse currents was inversely proportional to the distance between the down-conductor and measuring point. The amplitude of the magnetic flux density for PVC Pipe with down-conductor was 72 $\mu$T/㎷ at the distance of 1m and was higher than for steel conduits and coaxial cable. Finally the magnetic flux density is increased with increasing the di/dt it and oscillation frequency of lightning currents in this experimental ranges.

The Effect of Pad Groove Density on CMP Characteristics (패드 그루브의 밀도변화가 연마특성에 미치는 영향)

  • Park Kihyun;Jung Jaewoo;Lee Hyunseop;Seo Heondeok;Jeong Seokhun;Lee Sangjik;Jeong Haedo
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.22 no.8
    • /
    • pp.27-33
    • /
    • 2005
  • Polishing pads play an important role in chemical mechanical polishing(CMP) which has recently been recognized at the most effective method to achieve global planarization. In this paper, we have investigated CMP characteristics as a change of groove density of polishing pads. The parameter $(K_n)$ is proposed to estimate groove density of pad. The $K_n$ is defined as groove area divided by pitch area. As the groove density value increased, removal rate increased to some point and then gradually saturated in case of increasing the groove density excessively. In addition Within wafer non-uniformity(WIWNU) worse as groove density increased excessively, although WIWNU improved as groove density increased. Also the uniformity of temperature of pad surface decreased as the groove density increased. It was because that the cooling effect increased as groove density increased. In other words, increasing the groove density which means the apparent contact area of pad has influence on amount of discharge of slurry during polishing process.

Study on the Temporal Density Variation of Chemical Species in the Atmospheric Pressure Plasma Process (대기압 플라즈마 프로세스에 있어서 시간에 따른 화학종의 밀도변화 연구)

  • Han, Sang-Bo;Park, Sung-Su;Kim, Jong-Hyun;Park, Jae-Youn
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.27 no.7
    • /
    • pp.45-51
    • /
    • 2013
  • This study is to discuss simulation results with 51 principal chemical reactions in non-thermal plasma space under atmospheric pressure, and the ambient gas was mainly composed of oxygen and nitrogen molecules. The initial density of O and OH radicals under the ambient temperature of 300K is largely generated in comparison with other higher temperature, and the density of O radical decreased from $20{\mu}s$ according to increase the temperature. The initial density of OH radical seemed to decrease steeply at the initial stage. By increasing the initial density of $H_2O$ molecules, O radical's effect was few and the density of OH radical was largely generated about 2 times. In addition, ozone density was increased as increasing the density of O radical, but it was decreased as increasing the density of $H_2O$. In case of the temperature more than 300K, $NO_2$ tend to be removed, but NO was increased than the initial density.

Nonparametric Discontinuity Point Estimation in Density or Density Derivatives

  • Huh, Jib
    • Journal of the Korean Statistical Society
    • /
    • v.31 no.2
    • /
    • pp.261-276
    • /
    • 2002
  • Probability density or its derivatives may have a discontinuity/change point at an unknown location. We propose a method of estimating the location and the jump size of the discontinuity point based on kernel type density or density derivatives estimators with one-sided equivalent kernels. The rates of convergence of the proposed estimators are derived, and the finite-sample performances of the methods are illustrated by simulated examples.

Kinetic Analysis of the Effect of Cell Density on Hybridoma Cell Growth in Batch Culture

  • Lee, Eun-Yeol
    • Biotechnology and Bioprocess Engineering:BBE
    • /
    • v.7 no.2
    • /
    • pp.117-120
    • /
    • 2002
  • The effect of cell density on cell growth was investigated in a suspension batch culture of hybridoma cells. The specific growth rate was found to increase with increasing initial cell density and then to decrease with further increases in initial cell density. In order to quantitatively describe the dependence of specific growth rate on cell density, a kinetic model is proposed, which satisfactorily represents the experimental data.

Reducing Bias of the Minimum Hellinger Distance Estimator of a Location Parameter

  • Pak, Ro-Jin
    • Journal of the Korean Data and Information Science Society
    • /
    • v.17 no.1
    • /
    • pp.213-220
    • /
    • 2006
  • Since Beran (1977) developed the minimum Hellinger distance estimation, this method has been a popular topic in the field of robust estimation. In the process of defining a distance, a kernel density estimator has been widely used as a density estimator. In this article, however, we show that a combination of a kernel density estimator and an empirical density could result a smaller bias of the minimum Hellinger distance estimator than using just a kernel density estimator for a location parameter.

  • PDF

Historical Study on Density Smoothing in Nonparametric Statistics (비모수 통계학에서 밀도 추정의 평활에 관한 역사적 고찰)

  • 이승우
    • Journal for History of Mathematics
    • /
    • v.17 no.2
    • /
    • pp.15-20
    • /
    • 2004
  • We investigate the unbiasedness and consistency as the statistical properties of density estimators. We show histogram, kernel density estimation, and local adaptive smoothing as density smoothing in this paper. Also, the early and recent research on nonparametric density estimation is described and discussed.

  • PDF

Comparison of Estimation Methods for the Density on Expressways Using Vehicular Trajectory Data from a Radar Detector (레이더검지기의 차량궤적 정보기반의 고속도로 밀도산출방법에 관한 비교)

  • Kim, Sang-Gu;Han, Eum;Lee, Hwan-Pil;Kim, Hae;Yun, Ilsoo
    • International Journal of Highway Engineering
    • /
    • v.18 no.5
    • /
    • pp.117-125
    • /
    • 2016
  • PURPOSES : The density in uninterrupted traffic flow facilities plays an important role in representing the current status of traffic flow. For example, the density is used for the primary measures of effectiveness in the capacity analysis for freeway facilities. Therefore, the estimation of density has been a long and tough task for traffic engineers for a long time. This study was initiated to evaluate the performance of density values that were estimated using VDS data and two traditional methods, including a method using traffic flow theory and another method using occupancy by comparing the density values estimated using vehicular trajectory data generated from a radar detector. METHODS : In this study, a radar detector which can generate very accurate vehicular trajectory within the range of 250 m on the Joongbu expressway near to Dongseoul tollgate, where two VDS were already installed. The first task was to estimate densities using different data and methods. Thus, the density values were estimated using two traditional methods and the VDS data on the Joongbu expressway. The density values were compared with those estimated using the vehicular trajectory data in order to evaluate the quality of density estimation. Then, the relationship between the space mean speed and density were drawn using two sets of densities and speeds based on the VDS data and one set of those using the radar detector data. CONCLUSIONS : As a result, the three sets of density showed minor differences when the density values were under 20 vehicles per km per lane. However, as the density values become greater than 20 vehicles per km per lane, the three methods showed a significant difference among on another. The density using the vehicular trajectory data showed the lowest values in general. Based on the in-depth study, it was found out that the space mean speed plays a critical role in the calculation of density. The speed estimated from the VDS data was higher than that from the radar detector. In order to validate the difference in the speed data, the traffic flow models using the relationships between the space mean speed and the density were carefully examined in this study. Conclusively, the traffic flow models generated using the radar data seems to be more realistic.

Influence of Plant Density on Growth and Yield of Alisma plantago L. in Mono Cropping (재식밀도차이가 단작택사의 생육 및 수량에 미치는 영향)

  • 최달호;장영석;권병선;신종섭
    • Proceedings of the Plant Resources Society of Korea Conference
    • /
    • /
    • pp.34-37
    • /
    • 2000
  • To determine the optimum planting density in Alisma plantago in the southern areas of Korea, Alisma plantago local cultivar was grown under different planting density. The plant height, number of stems and diameter of root were 30cm, 12 and 3.4mm respectively on the planting density, row 20cm $\times$ intrarow 35cm. The fresh yield of root and dry yield of root were 261.2Kg110a, 211.5Kg/10a respectively on the planting density, row 20cm x intrarow 35cm. Therefore, the proper planting density for high yield bumper crop of Alisma plantago for exporting to Japan is planting density with row 20cm $\times$ intrarow 35cm.

  • PDF

Chararcteristics of Water Vapor Transmission in Base Resin for Underground Residential Distribution Power Cable (지중배전케이블 기저수지의 수증기 투과 전달특성)

  • Song, Jae-Joo;Han, Byung-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.149-153
    • /
    • 2003
  • In URD(Underground Residential Distribution) power cable, experiments of WVT(Water Vapor Transmission) test on the Base Resin accomplished to specimens which contained CB(Carbon Black), anti-oxidant to base resin and made by pressing to resin of pellet or lump form. a kind of specimens was HDPE(High Density Polyethylene), MDPE(Medium Density Polyethylene), LDPE(Low Density Polyethylene), LLDPE(Linear Low Density Polyethylene), PVC(Polyvinyl Chloride). as a results of WVT test, we saw that WVT ratio was HDPE < LLDPE < MDPE≒LDPE${\ll}$ PVC. WVT properties of PVC using for jacket showed properties 15-20 times more than MDPE or LLDPE. Therefore, to development of watertightness cable, our works present need of Changing in insulating materials.

  • PDF