• Title/Summary/Keyword: density analysis

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Investigation of the Cryogenic Performance of the High Density Polyurethane Foam (고밀도 폴리우레탄 폼의 극저온 성능 분석)

  • Jeong-Hyeon Kim;Jeong-Dae Kim;Tae-Wook Kim;Seul-Kee Kim;Jae-Myung Lee
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.6_3
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    • pp.1289-1295
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    • 2023
  • Polyurethane foam insulation required for storing and transporting cryogenic liquefied gas is already widely used as a thermal insulation material for commercial LNG carriers and onshore due to its stable price and high insulation performance. These polyurethane foams are reported to have different mechanical performance depending on the density, and the density parameter is determined depending on the amount of the blowing agent. In this study, density-dependent polyurethane foam was fabricated by adjusting the amount of blowing agent. The mechanical properties of polyurethane foam were analyzed in the room temperature and cryogenic temperature range of -163℃ at 1.5 mm/min, which is a quasi-static load range, and the cells were observed through microstructure analysis. The characteristics of linear elasticity, plateau, and densification, which are quasi-static mechanical behaviors of polyurethane foam, were shown, and the correlation between density and mechanical properties in a cryogenic environment was confirmed. The correlation between mechanical behavior and cell size was also analyzed through SEM morphology analysis. Polyurethane foam with a density of 180 kg/m3 had a density about twice as high as that of a polyurethane foam with a density of 96 kg/m3, but yield strength was about 51% higher and cell size was about 9.5% smaller.

Performance Predictions of the Planar-type Solid Oxide Fuel Cell with Computational Flow Analysis (I) - Isothermal Model - (유동 해석을 이용한 평판형 고체 산화물 연료전지의 성능 특성 분석 (I) - 등온 모델 -)

  • Hyun, Hee-Chul;Sohn, Jeong L.;Lee, Joon-Sik;Ro, Sung-Tack
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.5
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    • pp.635-643
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    • 2003
  • Parametric study for the analysis of performance characteristics of a planar -type solid oxide fuel cell(SOFC) using computational flow analysis is conducted. A planar -type SOFC, which is composed by two gas channels (fuel and ai.) and one set of anode-electrolyte-cathode assembly, is modeled as a two -dimensional isothermal case. Results of computational analysis of flow field including distributions of mass fractions in gas channels are used to the performance analysis of the fuel cell. Flow analysis makes it possible to consider current density distributions along the length of the cell in the process of performance analysis of the SOFC. As results of parametric study, it is found that the mole fraction of fuel at the inlet of fuel channel, operating pressure and temperature are closely related to the performance characteristics of SOFC.

Stability Analysis of Reacting Wakes (반응성 후류유동의 불안정성 해석)

  • Shin, D.S.;Hong, S.J.;Park, S.H.
    • Journal of the Korean Society of Combustion
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    • v.2 no.1
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    • pp.9-16
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    • 1997
  • This paper investigates the linear stability of wakes with special emphasis on the difference of velocity and density. Velocity and density profiles for laminar flows have gaussian profiles. Incompressible wakes have two generalized inflection points and two unstable modes-sinuous and varicose modes. Sinuous modes are more unstable than varicose modes irrespective of density variation, which shows wakes will be destabilized by sinuous modes. Large velocity difference and density difference leads to more unstable wakes due to large momentum difference.

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Availability of 2-Dimensional Vector Magnetic Property for High Flux Density Machines

  • Enokizono Masato
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.1
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    • pp.1-5
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    • 2005
  • The vector magnetic property is defined as the relationship between the magnetic field strength vector H and the magnetic flux density vector B. It is very important for the development of high efficiency and the high-density electric machines. The electrical steel sheet for the machine core shows the remarkable vector behavior by the high magnetic flux density level. In this paper, the magnetic characteristic analysis using E&S2 model is introduced as the useful technology for the design and development.

Relationship between Hardness and Relative Ddensity in Sintered Metal Powder Compacts (금속분발소결체의 경도와 상대밀도 관계)

  • 박종진
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1998.03a
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    • pp.168-174
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    • 1998
  • In the present study, a method for measuring the relative density by the hardness measurement was proposed for sintered metal powder compacts. It is based on the indentation force equation, by which the relative density is related with the hardness, that was obtained by the finite element analysis of rigid-ball indentation on sintered metal powder compacts. For verifying the method, it was applied to prediction of density distributions in sintered and sintered-and-forged Fe-0.5%C-2%Cu powder compacts.

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OPTIMAL CONTROL PROBLEM FOR HOST-PATHOGEN MODEL

  • P. T. Sowndarrajan
    • Nonlinear Functional Analysis and Applications
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    • v.28 no.3
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    • pp.659-670
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    • 2023
  • In this paper, we study the distributed optimal control problem of a coupled system of the host-pathogen model. The system consists of the density of the susceptible host, the density of the infected host, and the density of pathogen particles. Our main goal is to minimize the infected density and also to decrease the cost of the drugs administered. First, we prove the existence and uniqueness of solutions for the proposed problem. Then, the existence of the optimal control is established and necessary optimality conditions are also derived.

Analysis of ITO on Polymer Substrate by External Bending Force

  • Han, Jin-Woo;Kim, Young-Hwan;Kim, Jong-Hwan;Hwang, Jeoung-Yeon;Seo, Dae-Shik
    • Transactions on Electrical and Electronic Materials
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    • v.6 no.4
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    • pp.149-153
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    • 2005
  • In this paper, we investigated the island density-dependent stress distribution of indium-tin-oxide (ITO) film on polycarbonate substrate by external bending force. We used e-beam and RF­sputter for SiON, ITO sputtering. It was found that there are influence of island density on the substrate and decreasing crack density as goes to the minimum density. From the result that crack density was increasing at maximum island density, it is evident that more stress is imposed on same island position as island density.

Calculation of Force Density in Linear Motor Using Equivalent Magnetic Circuit (등가자기회로를 이용한 리니어모터의 추력밀도계산)

  • Hong, Jung-Pyo;Kang, Do-Hyun;Joo, Soo-Won;Hahn, Sung-Chin
    • Proceedings of the KIEE Conference
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    • 2001.04a
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    • pp.96-98
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    • 2001
  • In this paper, the equivalent magnetic circuit and FEM are used to calculate force density of linear BLDC motor. The equivalent magnetic circuit is hard to exact compose for analysis model and it is just applied to linear system. To flexible design and reducing the calculated and analyzed time, magnetic circuit has to be used for designing the linear BLDC motor and deducing equation of force density. Force density as parameter of permanent magnet and coil-side width that are important to determined force density can be estimated using equation of force density. FEM is used to prove reliability of equation of force density and to consider the nonlinear system. Equivalent magnetic circuit and result of FEM are similar, but it is little different by friction loss at the experiment.

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User Density Estimation System at Closed Space using High Frequency and Smart device

  • Chung, Myoungbeom
    • Journal of the Korea Society of Computer and Information
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    • v.22 no.11
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    • pp.49-55
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    • 2017
  • Recently, for safety of people, there are proposed so many technologies which detect density of people at the specific place or space. The representative technology for crowd density estimation was using image analysis method from CCTV images. However, this method had a weakness which could not be used and which's accuracy was lower at the dark or smog space. Therefore, in this paper, to solve this problem, we proposed a user density estimation system at closed space using high frequency and smart device. The system send inaudible high frequencies to smart devices and it count the smart devices which detect the high frequencies on the space. We tested real-time user density with the proposed system and ten smart devices to evaluate performance. According to the testing results, we confirmed that the proposed system's accuracy was 95% and it was very useful. Thus, because the proposed system could estimate about user density at specific space exactly, it could be useful technology for safety of people and measurement of space use state at indoor space.