• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1151-1156
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• 2013

In this study, to clearly establish the concept of a geometric modeling I apply for the concept of Pushbroom, limited to two-dimensional radiation Locator to provide a three-dimensional information purposes. Respect to the radiation scanner Pushbroom modeling techniques, geometric modeling method was presented introduced to extract three-dimensional information as long as the rotational component of the Gamma-Ray Linear Pushbroom Stereo System, introduced the two-dimensional and three-dimensional spatial information in the matching relation that can be induced. In addition, the pseudo-inverse matrix by using the conventional least-squares method, GCP(Ground Control Point) to demonstrate compliance by calculating the key parameters. Projection transformation matrix is calculated for obtaining three-dimensional information from two-dimensional information can be used as the primary relationship, and through the application of a radiation image matching technology will make it possible to extract three-dimensional information from two-dimensional X-ray imaging.

• Earthquakes and Structures
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• v.11 no.4
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• pp.649-664
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• 2016

A seismic damaged bridge may be hit again by a strong aftershock or another earthquake in a short interval before the repair work has been done. However, discussions about the impact of the unrepaired damages on the residual earthquake resistance of a steel bridge are very scarce at present. In this paper, nonlinear time-history analysis of a steel arch bridge was performed using multi-scale hybrid model. Two strong historical records of main shock-aftershock sequences were taken as the input ground motions during the dynamic analysis. The strain response, local deformation and the accumulation of plasticity of the bridge with and without unrepaired seismic damage were compared. Moreover, the effect of earthquake sequence on crack initiation caused by low-cycle fatigue of the steel bridge was investigated. The results show that seismic damage has little impact on the overall structural displacement response during the aftershock. The residual local deformation, strain response and the cumulative equivalent plastic strain are affected to some extent by the unrepaired damage. Low-cycle fatigue of the steel arch bridge is not induced by the earthquake sequences. Damage indexes of low-cycle fatigue predicted based on different theories are not exactly the same.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.1
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• pp.43-51
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• 2020

In this study, numerical analysis was carried out on a complex pressure field of blast waves caused by the detonation of high explosives in various environments. The generated blast waves propagated in the air, upon the sudden release of high energy induced by the explosion. Reflected waves were created when the pressure waves encountered certain obstacles such as the ground or the walls of structures. The propagation of the blast waves and its interaction with the reflected waves were simulated. An adaptive mesh refinement was applied to improve the efficiency of distribution of computer resource, for the computational calculation of the blast wave propagation in a wide open space. In addition, the integration of the calculation domains for the explosive and air were considered when the maximum density of the explosive region was below critical value. The results were verified by comparison with the pressure time history from blast wave experiments performed under two topographical conditions.

• Journal of Astronomy and Space Sciences
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• v.18 no.2
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• pp.137-144
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• 2001

This paper presents the REA thrusters performance estimation results for the KOREASAT F1&F2 launched in 1995 The satellite tracking data obtained from the ground system from end of 1999 to beginning of the 2000 are used to estimate the thruster performance. The estimation algorithm is derived from the least square estimation theory and designed to estimate the velocity change induced by the on-boarded thruster firing as well as the orbit parameter. The estimation results show that the Koreasat F1 thruster are in bad thruster condition of 64% performance for REA when it fires in on-pulse mode. Here, the performance is defined by the ratio of the resulted velocity change to that of planned. But, in the case o( the Koreasat F2, it is found that the performance approximately reaches up to 100%, even after the 5 years of the mission.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.1
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• pp.5-14
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• 2002

In this paper, we analyze inductive interference in conductive material around 345 kV power transmission line, and evaluate the effects of mitigation wires. Finite element method (FEM) is used to numerically compute induced eddy currents as well as magnetic fields around powder transmission lines. In the analysis model, geometries and electrical properties of various elements such as power transmission line, buried pipe lines, overhead ground wire, and conducting earth are taken into accounts. The calculation shows that mitigation wire reduces fairly good amount of eddy currents in buried pipe line. To find the optimum magnetic field shielding location of mitigation wire, we applied evolution strategy algorithm, a kind of stochastic approach, to the analysis model. Finally, it was shown that we can find more effective shielding effects with optimum location of one mitigation wire than with arbitrary location of multi-mitigation wires around the buried pipe lines.

• Earthquakes and Structures
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• v.6 no.4
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• pp.351-373
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• 2014

This paper investigates the seismic response of lightweight acceleration-sensitive non-structural components (NSCs) mounted on irregular reinforced concrete (RC) primary structures (P-structures) using non-linear dynamic finite element (FE) analysis. The aim of this paper is to study the influence of NSC to P-structure vibration period ratio, peak ground acceleration, NSC to P-structure height ratio, and P-structure torsional behaviour on the seismic response of the NSCs. Representative constitutive models were used to simulate the behaviour of the RC P-structures. The NSCs were modelled as vertical cantilevers fixed at their bases with masses on the free ends and varying lengths so as to match the frequencies of the P-structures. Full dynamic interaction is considered between the NSCs and P-structures. A set of 21 natural and artificial earthquake records were used to evaluate the seismic response of the NSCs. The numerical results indicate that the behaviour of the NSCs is significantly influenced by the investigated parameters. Comparison between the FE results and Eurocode (EC8) predictions suggests that EC8 underestimates the response of NSCs mounted on the flexible sides of irregular RC P-structures when the fundamental periods and heights of the NSCs match those of the P-structures. The perceived cause of this discrepancy is that EC8 does not take into account the amplification in the dynamic response of NSCs induced by the torsional behaviour of RC P-structures.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1706-1712
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• 2014

The OH($X^2{\Pi}$, ${\upsilon}^{\prime\prime}=0,1$) internal state distribution following the reaction of electronically excited oxygen atom ($O(^1D_2)$) with cyclo-$C_3H_6$ has been measured using laser-induced fluorescence, and compared with that following the reaction of $O(^1D_2)$ with $C_3H_8$. The overall characteristics of the OH internal energy distributions for both reactions were qualitatively similar. The population propensity of the ${\Pi}(A^{\prime})$ ${\Lambda}$-doublet sub-level suggested that both reactions proceeded via an insertion/elimination mechanism. Bimodal rotational population distributions supported the existence of two parallel mechanisms for OH production, i.e., statistical insertion and nonstatistical insertion. However, detailed analysis revealed that, despite the higher exoergicity of the reaction, the rotational distribution of the OH following the reaction of $O(^1D_2)$ with $C_3H_8$ was significantly cooler than that with cyclo-$C_3H_6$, especially in the vibrational ground state. This observation was interpreted as the effect of the flexibility of the insertion complex and faster intramolecular vibrational relaxation (IVR).

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2343-2353
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• 2007

We report the application of time-dependent density functional theory (TDDFT) to the calculation of potential energy profile relevant to the excited state intramolecular proton transfer (ESIPT) processes in title molecules. The TDDFT single point energy calculations along the reaction path have been performed using the CIS optimized structure in the excited state. In addition to the Stokes shifts, the transition energies including absorption, fluorescence, and 0-0 transition are estimated from the TDDFT potential energy profiles along the proton transfer coordinate. The excited state TDDFT potential energy profile of SA and 3ASA resulted in very flat function of the OH distance in the range ROH = 1.0-1.6 A, in contrast to the relatively deep single minimum function in the ground state. Furthermore, we obtained very shallow double minima in the excited state potential energy profile of SA and 3ASA in contrast to the single minimum observed in the previous work. The change of potential energy profile along the reaction path induced by the substitution of electron donating groups (-NH2 and -OCH3) at different sites has been investigated. Substitution at para position with respect to the phenolic OH group showed strong suppression of excited state proton dislocation compared with unsubstitued SA, while substitution at ortho position hardly affected the shape of the ESIPT curve. The TDDFT results are discussed in comparison with those of CASPT2 method.

• Structural Engineering and Mechanics
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• v.36 no.3
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• pp.321-341
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• 2010

The seismic-induced failure of a dam could have catastrophic consequences associated with the sudden release of the impounded reservoir. Depending on the severity of the seismic hazard, the characteristics and size of the dam-reservoir system, preventing such a failure scenario could be a problem of critical importance. In many cases, the release of water is controlled through a reinforced-concrete intake tower. This paper describes the application of a static nonlinear procedure known as the Capacity Spectrum Method (CSM) to evaluate the structural integrity of intake towers subject to seismic ground motion. Three variants of the CSM are considered: a multimodal pushover scheme, which uses the idea proposed by Chopra and Goel (2002); an adaptive pushover variant, in which the change in the stiffness of the structure is considered; and a combination of both approaches. The effects caused by the water surrounding the intake tower, as well as any water contained inside the hollow structure, are accounted for by added hydrodynamic masses. A typical structure is used as a case study, and the accuracy of the CSM analyses is assessed with time history analyses performed using commercial and structural analysis programs developed in Matlab.

• Computers and Concrete
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• v.21 no.1
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• pp.55-66
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• 2018

A large main shock may consist of numerous aftershocks with a short period. The aftershocks induced by a large main shock can cause the collapse of a structure that has been already damaged by the preceding main shock. These aftershocks are important factors in structural damages. Furthermore, despite what is often assumed in seismic design codes, earthquakes do not usually occur as a single event, but as a series of strong aftershocks and even fore shocks. For this reason, this study investigates the effect and potential of consecutive earthquakes on the response and behavior of concrete structures. At first, six moment resisting concrete frames with 3, 5, 7, 10, 12 and 15 stories are designed and analyzed under two different records with seismic sequences from real and artificial cases. The damage states of the model frames were then measured by the Park and Ang's damage index. From the results of this investigation, it is observed that the sequences of ground motions can almost double the accumulated damage and increased response of structures. Therefore, it is certainly insufficient to ignore this effect in the design procedure of structures. Also, the use of artificial seismic sequences as design earthquake can lead to non-conservative prediction of behavior and damage of structures under real seismic sequences.