• Journal of Korean Association for Spatial Structures
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• v.6 no.4 s.22
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• pp.35-44
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• 2006

The form-resistant Systems like a dome and shell are used more widely than post-beam structure system in large space structure. Single layer latticed dome system, one of the form-resistant system, has great merits in manufacturing and constructing but the failure mechanism is not clarified yet. The purpose of this paper is to find out the buckling characteristics of single-layer latticed domes with square network by using the experimental method. Major test parameters are the stiffness of lattice member and space of square lattice. The specimens are applied uniform loading of snow type.

• Journal of applied mathematics & informatics
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• v.11 no.1_2
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• pp.431-436
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• 2003

Given vectors x and y in a Hilbert space, an interpolating operator is a bounded operator T such that Tx = y. An interpolating operator for n vectors satisfies the equation $Tx_i\;:\;y_i,\;for\;i\;=\;1,\;2,\;{\cdots},\;n$. In this article, we obtained the following : $Let\;x\;=\;\{x_i\}\;and\;y=\{y_\}$ be two vectors in a separable complex Hilbert space H such that $x_i\;\neq\;0$ for all $i\;=\;1,\;2;\cdots$. Let L be a commutative subspace lattice on H. Then the following statements are equivalent. (1) $sup\;\{\frac{\$\mid${\sum_{k=1}}^l\;\alpha_{\kappa}E_{\kappa}y\$\mid$}{\$\mid${\sum_{k=1}}^l\;\alpha_{\kappa}E_{\kappa}x\$\mid$}\;:\;l\;\in\;\mathbb{N},\;\alpha_{\kappa}\;\in\;\mathbb{C}\;and\;E_{\kappa}\;\in\;L\}\;<\;\infty\;and\;$\mid$y_n\$\mid$x_n$\mid$^{-1}\;=\;1\;for\;all\;n\;=\;1,\;2,\;\cdots$. (2) There exists an operator A in AlgL such that Ax = y, A is a unitary operator and every E in L reduces, A, where AlgL is a tridiagonal algebra.

• Electrical & Electronic Materials
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• v.8 no.6
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• pp.780-786
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• 1995

For the execution of RIETAN program adopting Rietveld Analysis Method, the sample superconductor is made according to the solid state synthesis method at 920.deg. C for 24hrs, and was examined for the optimization of parameters needed to analyze Rietveld method with the input of the measured pattern data after measuring the pattern resulted from the X-ray diffraction. It was proven that the lattice constant of the superconductor which was consisted of Pmmm orthorhombic crystal structure in the analyzed space group correspond to the presented theoretical lattice constant a=3.8887(8).angs., b=3.8238(4).angs., c=11.7079.angs.. Therefore, it was examined and confin-ned that the R factor, which was compensated after analyzing the structure of superconductor resulted from this experimented data with the computer simulation, was refined to $R_{wp}$=8.83[%], $R_{P}$=6.47[%], $R_{I}$=10.08[%], $R_{F}$=7.19[%], $R_{E}$=3.76[%]. On the basis of these experimental data, the significant parameter such as the scale factor(S) and the zero point shift(Z) and FWHM value(U,V,W) were optimized as follows; S=2.0827E-3, Z=0.2146, U=4.2761E-2, V=1.7983E-2, and W=2.6768E-2.2.2.2.2.2.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.474-484
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• 2017

This paper studies the applicability of an efficient numerical model based on artificial neural networks (ANNs) to predict the dynamic responses of the wing structure of an airplane due to atmospheric turbulence in the time domain. The turbulence velocity is given in the form of a stationary Gaussian random process with the von Karman power spectral density. The wing structure is modeled by a classical beam considering bending and torsional deformations. An unsteady vortex-lattice method is applied to estimate the aerodynamic pressure distribution on the wing surface. Initially, the trim condition is obtained, then structural dynamic responses are computed. The numerical solution of the wing structure's responses to a random turbulence profile is used as a training data for the ANN. The current ANN is a three-layer network with the output fed back to the input layer through delays. The results from this study have validated the proposed low-cost ANN model for the predictions of dynamic responses of wing structures due to atmospheric turbulence. The accuracy of the predicted results by the ANN was discussed. The paper indicated that predictions for the bending moments are more accurate than those for the torsional moments of the wing structure.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.1
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• pp.1-9
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• 2021

The martensitic stainless steel has excellent corrosion resistance and higher strength by quenching and tempering heat treatment. It has been widely used as blade material due to these properties. The hardness and impact toughness of martensitic stainless steel depended strongly on tempering temperatures. The 12Cr martensite stainless steel (SS 410) tempered about 540℃ showed temper embrittlement. To know cause of temper embrittlement in terms of phase identification, a detailed analysis of electron diffraction patterns during TEM observations has been carried out on the <110>α-Fe and <113>α-Fe zone axes for temper embrittlement specimen. The double electron diffraction spots at 1/3(211) and 2/3(211) positions were observed. The lattice space between individual diffraction spots was about 3.5 Å and this value coincide with three times to α-bcc lattice space (1.17 Å). The area which found double diffraction spots was judged metastable "zone" similar to the omega phase and induced embrittlement of SS410 material.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.923-928
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• 2003

This paper presents the motion control of a mobile robot with arc sensor for lattice type welding. Its dynamic equation and motion control method for welding speed and seam tracking are described. The motion control is realized in the view of keeping constant welding speed and precise target line even though the robot is driven along a straight line or comer. The mobile robot is modeled based on Lagrange equation under nonholonomic constraints and the model is represented in state space form. The motion control of the mobile robot is separated into three driving motions of straight locomotion, turning locomotion and torch slider controls. For the torch slider control, the proportional integral derivative (PID) control method is used. For the straight locomotion, a concept of decoupling method between input and output is adopted and for the turning locomotion, the turning speed is controlled according to the angular velocity value at each point of the comer with range of $90^{\circ}$ constrained to the welding speed. The proposed control methods are proved through simulation results and the results have proved that the mobile robot has enough ability to apply the lattice type welding line.

• Journal of Mechanical Science and Technology
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• v.16 no.1
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• pp.83-93
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• 2002

This paper presents a motion control method and its simulation results of a mobile robot for a lattice type welding. Its dynamic equation and motion control methods for welding speed and seam tracking are described. The motion control is realized in the view of keeping constant welding speed and precise target line even though the robot is driven for following straight line or curve. The mobile robot is modeled based on Lagrange equation under nonholonomic constraints and the model is represented in state space form. The motion control of the mobile robot is separated into three driving motions of straight locomotion, turning locomotion and torch slider control. For the torch slider control, the proportional-integral-derivative (PID) control method is used. For the straight locomotion, a concept of decoupling method between input and output is adopted and for the turning locomotion, the turning speed is controlled according to the angular velocity value at each point of the corner with range of 90$^{\circ}$ constrained to the welding speed. The proposed control methods are proved through simulation results and these results have proved that the mobile robot has enough ability to apply the lattice type welding line.

• Journal of Korean Association for Spatial Structures
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• v.23 no.4
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• pp.27-34
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• 2023

In this study, the seismic response characteristics of the three analysis model with or without TMD were investigated to find out the effective dome shape. The three analysis models are rib type, lattice type and geodesic type dome structure composed of space frame. The maximum vertical and horizontal displacements were evaluated at 1/4 point of the span by applying the resonance harmonic load and historical earthquake loads (El Centro, Kobe, Northridge earthquakes). The study of the effective TMD installation position for the dome structure shows that seismic response control was effective when eight TMDs were installed in all types of analysis model. The investigation of the efficiency of TMD according to dome shape presents that lattice dome and geodesic dome show excellent control performance, while rib dome shows different control performance depending on the historical seismic loads. Therefore, lattice and geodesic types are desirable for seismic response reduction using TMD compared to rib type.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.161-164
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• 2008

Demands for space structures such as domes have increased in Korea. Generally, typical methods for connections of the space structures have technical limits in the space distances of the single latticed domes between supports. In this paper, improved welded joints for single-layer lattice domes was suggested and compared with the existing connections of the single layer latticed domes through both analytical and experimental studies.

• The Pure and Applied Mathematics
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• v.21 no.2
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• pp.113-120
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• 2014

In this paper, we first show that for any space X, there is a ${\sigma}$-complete Boolean subalgebra of $\mathcal{R}$(X) and that the subspace {${\alpha}{\mid}{\alpha}$ is a fixed ${\sigma}Z(X)^{\sharp}$-ultrafilter} of the Stone-space $S(Z({\Lambda}_X)^{\sharp})$ is the minimal basically disconnected cover of X. Using this, we will show that for any countably locally weakly Lindel$\ddot{o}$f space X, the set {$M{\mid}M$ is a ${\sigma}$-complete Boolean subalgebra of $\mathcal{R}$(X) containing $Z(X)^{\sharp}$ and $s_M^{-1}(X)$ is basically disconnected}, when partially ordered by inclusion, becomes a complete lattice.