• Bulletin of the Society of Naval Architects of Korea
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• v.10 no.1
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• pp.15-20
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• 1973

In this paper, it is desired to show a simplified analytical method in estimating the thermal stresses in the heat affected zone of butt welded joint. A finite strip as shown in Fig.1 is taken as a analytical model for stress analysis. Expressing the temperature distributions by Fourier series, the thermal stresses are obtained. From the numerical sample calculation, the following results can be obtained. (1) Thermal stresses can be estimated by the sujected method. (2) The stress component, which is parallel to the weld direction is the largest stress component in major part of the strip. (3) In obtaining a stress component for the engineering purpose, length of the strip can be treated as five times of the thickness with same degree of convergency.

• Journal of the Korean Society for Railway
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• v.9 no.1 s.32
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• pp.57-62
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• 2006

Composite thin-walled members for civil engineering application are mainly produced by pultrusion technique, and they are generally made of a polymeric resin system reinforced by E-glass fibers due to economical reason. This material combination results in low elastic moduli of the composite materials and makes the design of composite members to be governed by stability limit state. Therefore the buckling behavior of composite thin-walled members was experimentally investigated in the present study. Axial compression was applied on each specimens by a hydraulic ram and knife edge fixtures were placed at both ends to simulate simple boundary condition. Axial compression, lateral displacements and twisting at the mid-height of each specimen were measured by a set of transducers during buckling test. The experimental buckling loads were compared with analytical results obtained through isotropic formulas. In the calculation of analytical results, elastic properties such as Young's modulus(E) and shear modulus(G) were replaced with EL and GLT obtained from coupon tests, respectively.

• Steel and Composite Structures
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• v.20 no.1
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• pp.71-89
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• 2016

In steel and concrete composite girders, the load transfer between the steel beam and the concrete slab is commonly ensured by installing shear connectors. In this paper, to investigate the nonlinear behavior of perfobond connectors, a total of 60 push-out specimens were fabricated and tested with the variables for the hole diameter, the concrete strength, the thickness of concrete slab, the diameter, strength and existence of perforating rebar, the thickness, height and distance of perfobond ribs. The failure mode and the load-slip behavior of perfobond connectors were obtained. A theoretical model was put forward to express the load-slip relationship. Analytical formulas of shear capacity and peak slip were also proposed considering the interaction between the concrete dowel and the perforating rebar. The calculation results of the proposals agreed well with the experimental values.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.603-610
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• 2008

In this paper, analytical methods for calculating the average probability of bit error of direct sequence pulse amplitude modulation ultra wideband (DS-PAM UWB) system and time hopping pulse position modulation ultra wideband (TH-PPM UWB) system are given. For the multi-user DS-PAM UWB system, the bipolar pulse amplitude modulation is used in order to achieve better performance. As we know, more attention is paid to the TH-PPM UWB systems recently. In this paper. we first introduce the accurate BER calculation methods of the multi-user DS-PAM UWB and TH-PPM UWB systems and then give the performance analysis over the ideal AWGN channel and a correlation receiver. Furthermore, we also introduce their applications in image transmission and data transmission and give the simulation results. The analytical method yields simple and exact formulas relating the performance to the system parameters.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.41-45
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• 1999

Analytical and experimental investigations have been carried out on the gas pulsations in the discharge paths of a high-side horizontal scroll compressor, where the gas discharged from compression chamber is made to pass through several chambers inside the compressor shell. Model of Helmholtz resonators in series has been applied to this configuration to predict gas pulsation phenomena along the passages, and the calculation results have been compared with measured pressure time traces. Good agreements between the analytical and experimental results have been obtained. It has also been found that the compressor performance is somewhat affected by the size of individual chambers Inside the compressor shell.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.11
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• pp.2773-2781
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• 1993

Laplace's equation is, perhaps, the most important equation, which governs various kinds of physical phenomena. Due to its importance, there have been several numerical techniques such as the finite element method, the finite difference method, and the boundary element method. However, these techniques do not appear very effective as they require a substantial amount of numerical calculation. In this paper, we develop a new most efficient technique based on analytic solutions for Laplace's equation in some convex polygons. Although a similar approach was used for the same problem, the present technique is unique as it solves directly Laplace's equation with the utilization of analytical solutions.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.298-306
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• 2018

This paper presents a harmonic analysis of the modular multilevel converter (MMC) using a double Fourier series (DFS) algorithm. First, the application of DFS for harmonic calculation in the MMC is made by considering the effect of arm inductor. The analytical results are then confirmed by comparing with the simulation results of using the fast Fourier transform (FFT) algorithm. Finally, distribution of harmonics and total harmonic distortion (THD) in the MMC will be analyzed in three cases: harmonics versus number of levels of MMC, harmonics versus total switching frequency and harmonics versus modulation index. The simulation results are performed in the PSCAD/EMTDC simulation program in order to verify the analytical results obtained by Matlab programming.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.652-665
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• 2019

Analytical solutions of the reactant concentration inside porous spherical catalytic particles were obtained from unsteady reaction-diffusion equation by applying eigenfunction expansion method. Various surface concentrations as exponentially decaying or oscillating function were considered as boundary conditions to solve the unsteady partial differential equation as a function of radial distance and time. Dirac delta function was also used for the instantaneous injection of the reactant as the surface boundary condition to calculate average reactant concentration inside the particles as a function of time by Laplace transform. Besides spherical morphology, other geometries of particles, such as cylinder or slab, were considered to obtain the solution of the reaction-diffusion equation, and the results were compared with the solution in spherical coordinate. The concentration inside the particles based on calculation was compared with the bulk concentration of the reactant molecules measured by photocatalytic decomposition as a function of time.

• Analytical Science and Technology
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• v.34 no.1
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• pp.17-22
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• 2021

In this study, flame retardant mixtures of decabromodiphenylethane (DBDPE) and Sb2O3 were analyzed using Fourier transform infrared (FT-IR) spectroscopy. The experimentally obtained wavenumbers of DBDPE and Sb2O3 were 1321 and 949 cm-1, respectively, whereas those obtained by theoretical calculation were 1370 and 818 cm-1, respectively. Strong correlation was observed between the mixing molar ratios and observed peak area ratios, suggesting that FT-IR analysis can be used to obtain relative amounts of the individual components of flame retardant mixture.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.6
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• pp.253-263
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• 2023

Non-structural elements, such as equipment, are typically affixed to a building's floor or ceiling and move in tandem with the structure during an earthquake. Seismic forces acting upon non-structural elements traverse the ground and the building's structure. Considering this seismic load transmission mechanism, it becomes imperative to account for the interactions between soil, structure, and equipment, establishing seismic design procedures accordingly. In this study, a Soil-Structure-Equipment Interaction (SSEI) model is developed. Through seismic response analysis using this model, how the presence or absence of SSEI impacts equipment behavior is examined. Neglecting the SSEI aspect when assessing equipment responses results in an overly conservative evaluation of its seismic response. This emphasizes the necessity of proposing an analytical model and design methodology that adequately incorporate the interaction effect. Doing so enables the calculation of rational seismic forces and facilitates the seismic design of non-structural elements.