• The Bulletin of The Korean Astronomical Society
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• 제46권1호
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• pp.57.3-58
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• 2021

We performed three-dimensional Monte Carlo dust scattering radiative transfer simulations for FUV light to obtain dust scattered FUV images and compared them with the observed FUV image obtained by FIMS/SPEAR and GALEX. From this, we find the scattering properties of interstellar dust in our Galaxy and suggest the intensity of extragalactic background light (EBL) at FUV wavelength. The best-fit values of the scattering properties of interstellar dust are albedo = 0.38^-0.04_+0.04, g-factor = 0.55^-0.15_+0.10, and EBL = 138^-23₊₂₁ CU for the allsky which are consistent well with the Milky Way dust model of Draine and direct measurements of Gardner et al., respectively. At the high Galactic latitude of |b|>10°, the observation is well fitted with the model of lower albedo = 0.35^-0.04_+0.06 and g-factor = 0.50^-0.20_+0.15. On the contrary, the scattering properties of interstellar dust show higher albedo = 0.43^-0.02_+0.02 and g-factor = 0.65^-0.15_+0.05 near the Galactic plane of |b|<10°. In the present simulation, recent three-dimensional distribution maps of interstellar dust in our Galaxy, stellar distances in the catalog of GAIA DR2, and FUV fluxes and/or spectral types in the TD-1 and Hipparcos star catalogs were used.

• Journal of computational fluids engineering
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• 제13권2호
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• pp.20-26
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• 2008

A numerical study is carried out to analyze the steady three-dimensional turbulent flow and convective heat transfer in a staggered pin-fin array with diamond shaped elements at various geometrical configurations. Steady Reynolds-averaged Navier-Stokes equations and energy equation are solved using a finite volume based solver. Shear stress transport (SST) model is used as turbulence closure. The computational domain is composed of one pitch of pin-fin displacement with periodic boundary conditions on the surfaces normal to the streamwise direction and the cross-streamwise direction. The numerical results for Nusselt number and friction factor are validated with experimental results. The effects of pin angle, pin height and pitch on Nusselt number, friction factor and efficiency index are investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제23권6호
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• pp.961-967
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• 1999

A model is constructed to evaluate the mode III stress intensity factor(SIF) for orthotropic three-layered material with a center crack subjected to uniform anti-plane shear loading. A mixed boundary value problem is formulated by Fourier integral transform method and a Fredholm integral equation of the second kind is derived. The integral equation is numerically analyzed to evaluate the effects of the ratio of shear modulus, strength of each layer and crack length to layer thickness on the stress intensity factor.

• Journal of Applied Reliability
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• 제14권2호
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• pp.93-96
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• 2014

RFID (Radio Frequency IDentification) system is recognition technology which can maintain various object's information. Reliability of RFID tags is the most important factor in RFID system. In this paper, we proposed ALT (Accelerated Life Test) method for UHF RFID tags. Temperature and humidity were adopted as stress factors and the accelerated life tests were conducted in three different conditions. We performed failure analysis for identifying failure mechanism and statistical analysis of test data. In the statistical analysis, we employed Inverse Power law for relationship between tag's life and stress. Through the statistical analysis, we proposed acceleration factor for several levels of temperature-humidity. The reliability qualification test plans were also designed for the tag's target reliability.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.236-244
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• 2000

As the second part of the author's study, the aerodynamic blockage and the slip factor of 8 centrifugal compressor impellers are investigated, when the flow rate is changed from numerical stall to choke, using three-dimensional Navier-Stokes analysis results. Based on all the exit blockage distributions, an improved model equation with two adjusting coefficients is developed for the use in design processes with the agile engineering purpose. A popular expression of constant slip factors, the Wiesner's equation, cannot be applied in design processes when more accurate prediction is strongly required at design and off-design points. Slip factor variation is found to be also influenced by the blade loadings at midspan. When the flow rate is changed, a pattern of the slip factor variations is assumed to be a simple form which can be explained using midspan blade loading distributions.

• Journal of the military operations research society of Korea
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• 제11권2호
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• pp.6-14
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• 1985

The layered multi-barrier defense situation against penetrating enemy threat is analytically modeled towards minimizing the penetration probability. Each layer is characterized by probability of detection and probability of kill given detection. The two capabilities are assumed independent. Detection in a layer, however, affects detection performance in subsequent layers. The following three models were formulated and investigated: (1) 'Model A' permits increase of detection performance in only the next barrier, (2) 'Model B' permits the increase in all subsequent barriers linearly, and (3) 'Model C' expresses the increase in an asymptotic exponential way. The best and the worst barrier combinations are determined through model exercise and model performances are compared through sensitivity analysis for the 'intensification factor.'

• Steel and Composite Structures
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• 제18권6호
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• pp.1353-1368
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• 2015

A finite element model is presented for the analysis of composite steel-concrete beams based on a refined high-order theory. The employed theory satisfies all the kinematic and stress continuity conditions at the layer interfaces and considers effects of the transverse normal stress and transverse flexibility. The global displacement components, described by polynomial or combinations of polynomial and exponential expressions, are superposed on local ones chosen based on the layerwise or discrete-layer concepts. The present finite model does not need the incorporating any shear correction factor. Moreover, in the present $C^1$-continuous finite element model, the number of unknowns is independent of the number of layers. The proposed finite element model is validated by comparing the present results with those obtained from the three-dimensional (3D) finite element analysis. In addition to correctly predicting the distribution of all stress components of the composite steel-concrete beams, the proposed finite element model is computationally economic.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제21권48호
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• pp.299-310
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• 1998

Actually mixed assembly line is mixed with open and close type workstation. This workstation is called hybridworkstation. The propose of this paper is to determine the sequencing of model that minimize line length for actual(hybridworkstation) mixed model assembly line. we developed three mathematical formulation of the problem to minimize the overall length of a line with hybrid station. Mathematical formulation classified model by operato schedule. Mixed model assembly line is combination program and NP-hard program. Thus computation time is often a critical factor in choosing a method of determining the sequence. This study suggests a tabu search technique which can provide a near optimal solution in real time and use the hill climbing heuristic method for selecting initial solution. Modified tabu search method is compared with MIP(Mixed Integer Program). Numerical results are reported to demonstrate the efficiency of the method.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.604-607
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• 2003

Recently, hybrid concrete structures such as a concrete-filled steel tubular(CFT), a steel reinforced concrete(SRC) and a composite material are popular in structure applications. They also have merit of high strength, high ductility, and large energy absorption capacity. But the analysis of hybrid concrete structures is very difficult owing to the complex behavior of concrete under passive confinement. This paper has analyzed CFT, which receives passive confinement using Tri-Surface concrete model for three dimension finite element analysis. By the result of that, the proposed model was properly forecasted a concrete behavior that receives passive restraint as well as non-linear analysis of concrete which receive uniaxial stress and high active confinement of 400Mpa. If the model through the steady study is set up especially on the factor of concrete under passive confinement, the proposed concrete model will be surely useful for analysis of the hybrid concrete structures.

• Journal of Information Technology Applications and Management
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• 제10권1호
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• pp.71-89
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• 2003

This paper firstly introduces a classification model for designing the architecture of backup centers in terms of business continuity management. We propose that the replication solution, the level of disaster recovery, and the outsourcing style as three important factors that help explain the architecture of backup centers. We provide the details of each factor of the model and apply them to the real world cases of backup centers in Korea. We conclude that the model is well fitted to many cases of currently available backup centers and can provide backup center architects with a well classified architecture model with specific guidelines.