• Title/Summary/Keyword: Dispersion Degree

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Analysis on Trajectory and Impact Point Dispersion of Test Launch Vehicle (시험발사체 궤적 및 낙하점 분산 분석)

  • Song, Eun-Jung;Cho, Sangbum;Choi, Jiyoung;Lee, Sang-il;Kim, Younghoon;Sun, Byung-Chan
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.8
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    • pp.681-688
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    • 2021
  • This paper considers the trajectory and impact point dispersion analysis of the test launch vehicle (TLV). The analysis, which performed before and after its flight test on November 28, 2018, is described and verified by comparing with the flight test results. The six degree-offreedom (DOF) simulation is used to compute the dispersion of the trajectory, attitude, and impact point, where the launch vehicle performance variations and wind effects during the atmospheric phase are included. The impact area to guarantee the flight safety is determined using the results of the dispersion analysis. The flight test results confirm that the safe flight of TLV is performed within the predicted dispersion boundary.

A Note on Maximal Entropy OWA Operator Weights

  • Hong, Dug-Hun;Kim, Kyung-Tae
    • Journal of the Korean Data and Information Science Society
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    • v.17 no.2
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    • pp.537-541
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    • 2006
  • In this note, we give an elementary simple proof of the main result of $Full{\acute{e}}rand$ Majlender [Fuzzy Sets and systems 124(2001) 53-57] concerning obtaining maximal entropy OWA operator weights.

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Thermal Curing Property of Silicone Encapsulant Containing Quantum Dot Surrounded by Various Types of Ligands

  • Lee, Chae Sung;Kim, BeomJong;Jeon, Seongun;Han, Cheul Jong;Hong, Sung-Kyu
    • Bulletin of the Korean Chemical Society
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    • v.34 no.12
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    • pp.3787-3789
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    • 2013
  • In this study, the silicone thermal curing degree of the silicone-encapsulated quantum dot light emission diode was measured using the various types of chemical ligands around quantum dot. It was confirmed that the trioctyl phosphin oxide (TOPO) ligand around the quantum dot was responsible for dispersion of the quantum dot in silicone encapsulant and decline of the thermal curing degree of the silicone encapsulant. Also, it was confirmed that the thermal curing degree of silicone encapsulants containing the steric acid (SA) and the dodecanoic acid (DA) ligands were higher than the one of TOPO ligand.

Effect of Slag Particle Size and Volume Fraction on Mechanical Properties of Slag Reinforced Composite (슬래그 입자의 크기 및 체적비에 따른 슬래그 입자강화 복합재료의 기계적 특성 연구)

  • Nam, Ji-Hoon;Chun, Heoung-Jae;Hong, Ik-Pyo
    • Composites Research
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    • v.26 no.4
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    • pp.218-222
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    • 2013
  • This study demonstrated that a slag, an industrial solid waste, can be used as a structural reinforcement. The mechanical properties(tensile strength and Elastic modulus) of slag reinforced composite(SRC) was investigated as functions of slag particle size (8~12 ${\mu}m$ and 12~16 ${\mu}m$) and volume fraction (0-40 vol.%). In order to investigate the interface and a degree of particle dispersion which have an effect on mechanical properties, optical microscopic images were taken. The results of tensile tests showed that the tensile strength decreased with an increase in slag volume fraction and particle size. The elastic modulus increased with an increase in slag volume fraction and particle size except for 30 vol.% SRC. The tensile strength decreased with an increase in slag particle size. The microscopic picture showed SRC has fine degree of particle dispersion at low slag volume fraction. SRC has a good interface at every volume fraction. However particle cluster was incorporated with an increase in slag volume fraction.

An Eulerian-Lagrangian Hybrid Numerical Method for the Longitudinal Dispersion Equation (Eulerian-Lagrangian 혼합모형에 의한 종확산 방정식의 수치해법)

  • 전경수;이길성
    • Water for future
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    • v.26 no.3
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    • pp.137-148
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    • 1993
  • A hybrid finite difference method for the longitudinal dispersion equation was developed. The method is based on combining the Holly-Preissmann scheme with the fifth-degree Hermite interpolating polynomial and the generalized Crank-Nicholson scheme. Longitudinal dispersion of an instantaneously-loaded pollutant source was simulated by the model and other characteristics-based numerical methods. Computational results were compared with the exact solution. The present method was free from wiggles regardless of the Courant number, and exactly reproduced the location of the peak concentration. Overall accuracy of the computation increased for smaller value of the weighting factor, $\theta$ of the model. Larger values of $\theta$ overestimated the peak concentration. Smaller Courant number gave better accuracy, in general, but the sensitivity was very low, especially when the value of $\theta$ was small. From comparisons with the hybrid method using the third-degree interpolating polynomial and with split-operator methods, the present method showed the best performance in reproducing the exact solution as the advection becomes more dominant.

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Prediction of Wetting and Interfacial Property of CNT Reinforced Epoxy on CF Tow Using Electrical Resistance Method (전기저항 평가법을 이용한 CNT 함유 에폭시의 탄소섬유내 젖음성 및 계면특성 예측 연구)

  • Kwon, Dong-Jun;Choi, Jin-Yeong;Shin, Pyeong-Su;Lee, Hyung-Ik;Lee, Min-Gyeong;Park, Jong-Kyoo;Park, Joung-Man
    • Composites Research
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    • v.28 no.4
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    • pp.232-238
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    • 2015
  • As a new method to predict the degree of dispersion in carbon nanocomposites, the electrical resistance (ER) method has been evaluated. After CNT epoxy resin was dropped on CF tow, the change in electrical resistance of carbon fiber tow was measured to evaluate dispersion condition in CNT epoxy resin. Good dispersion of CNTs in carbon nanocomposite exhibited low change in ER due to wetted resin penetrated on CF tow. However, because CNT network was formed among CFs, non-uniform dispersion occurred due to nanoparticle filtering effect by CF tow. The change in ER for poor dispersion exhibited large ER signal change. The change in ER was used for the dispersion evaluation of CNT epoxy resin. Correlation between interlaminar shear strength (ILSS) and dispersion condition by ER method was established. Good CNT dispersion in nanocomposites led to good interfacial properties of fiberreinforced nanocomposites.

In-Line Monitoring the Dispersion of Highly Energetic Material Simulant (고에너지 물질 시뮬란트의 분산도의 In-Line 모니터링)

  • Lee, Sangmook;Hong, In-Kwon;Ahn, Youngjoon;Lee, Jae Wook
    • Polymer(Korea)
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    • v.38 no.3
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    • pp.272-277
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    • 2014
  • We studied in-line monitoring the dispersion of highly energetic material simulant by a twin screw extruder having a high temperature ultrasonic system. The simulant suspension system consisted of ethylene vinyl acetate and Dechlorane plus 25 as binder and filler, respectively. With increasing filling fraction, the ultrasonic velocity was not changed but the attenuation linearly decreased. It was possible to estimate the solid fraction of well dispersed suspension system by measuring ultrasonic attenuation. The ultrasonic attenuation of samples filled over 60 v% approached straight line with increasing filling fraction when the samples was extruded repeatedly. It was due to the enhanced dispersion of solid particles in the suspension system. It was believed that the degree of dispersion and filling fraction could be obtained by combination of on-line measurement like ultrasonic attenuation and off-line analysis like TGA and SEM with image analyzer.

Numerical Analysis for Improving of SOx Removal Efficiency in the DSI(Dry Sorbent Injection Technique) of FGD System(I) (배연탈황 공정 중 DSI 공법의 탈황효율 향상을 위한 전산 유체 역학적 연구(I))

  • Chung, Jin-Do;Kim, Jang-Woo;Kim, Byung-Hwan;Park, Young-Moon
    • Journal of Korean Society of Environmental Engineers
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    • v.29 no.1
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    • pp.47-53
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    • 2007
  • The aim of this study is to research applicable possibility or Dry Sorbent Injection Technique(DSI) in sox removal process using Computational Fluid Dynamics(CFD) software package. It will be applied for 500MW in capacity coal-fired thermal power plant operated by South Korea N. Power Co., Ltd. The DSI process is adapted between a preheater and an EP process in the technological assembly. The numerical analysis performs in predicting and optimizing of DSI process's characteristics, which consists of structure of duct, position of injection nozzles, injection speed, and dispersion of sorbent. Computing results are shown that degree of sorbent dispersion depends on structure of duct and position of injection nozzles strongly. The highest dispersion efficiency was obtained when we set a Lobed-plate inside the duct and 6 injection nozzles on the duct(4 injection nozzles at the corners and 2 injection nozzles on upper and under walls as a rectangle duct shape). We also know that change of injection speed of sorbent doesn't have an large effect on the sorbent dispersion but it can effect to drop pressure.

Strength and conversion characteristics of DeNOx catalysts with the addition of dispersion agent (분산제 첨가에 따른 탈질촉매의 강도세기 및 전환특성)

  • Lee, Hyun Hee;Park, Kwang Hee;Cha, Wang Seog
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.12
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    • pp.6575-6580
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    • 2013
  • Various modified SCR catalysts were prepared and tested to improve the strength of catalysts for use under severe conditions. The SCR catalysts were modified with a binder and dispersion agent, and tested at the fixed bed reactor. FT-IR and $H_2$-TPR were used to analyze the degree of hydrogen use and ammonia adsorption by the modified catalysts. In the case of the SCR catalysts coated with 2.3g of the binder, 4.7g of ethanol, and 0.1g of dispersion agent, the strength of catalyst was increased by approximately 12%. On the other hand, despite the enhancement of strength, the activities of the SCR catalysts were decreased by 2-10%. When the mixed solution composed of binder, dispersion agent and $SiO_2$ solution was precipitated on the catalyst, the $NO_x$ conversion of the catalyst was decreased slightly. The Bronsted acid site and Lewis acid site worked as the activators for the SCR reaction, and were decreased by $SiO_2$.

Wideband WDM Transmission through the Power Symmetry Method in the Mid-Span Spectral Inversion (Mid-Span Spectral Inversion을 이용한 광 펄스 왜곡의 보상에서 전력 대칭을 통한 광대역 WDM 전송)

  • 이성렬;이윤현
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.12 no.7
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    • pp.1157-1166
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    • 2001
  • In this paper, we investigated the degree of compensation for optical pulse shape distortion due to both chromatic dispersion and SPM(self phase modulation) in high speed optical transmission system with dispersion shift fiber. We adopted the power symmetric MSSI(mid-span spectral inversion) as compensation method. We used EOP(eye-opening penalty) parameter in order to evaluate the compensation efficiency of distorted optical pulse. We evaluated input signal power range being able to maintain stable reception performance in the case of various chirp parameter of modulated optical pulse. And, in order to verify the applicable to wideband WDM system, we evaluated the wavelength range being able to maintain stable reception performance through the EOP calculation of various dispersion coefficient of first fiber D$\_$11/. We showed that proposed MSSI is effective compensation method to down chirped optical pulse transmission rather than up chirped optical pulse transmission in anomalous dispersion range. And we showed that this method have possibility of relative high power transmission and wideband transmission in WDM system.

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