• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.540-545
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• 2000

This paper presents the exact dynamic element for composite Timoshenko beam, which is inherently subject both to bending and torsional vibration. The coupling effect between bending and torsional vibrations is rigorouly considered in the derivation of the exact dynamic element. Two examples are provided to validate and illustrate the proposed exact dynamic element matrix for composite Timoshenko beam.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.3
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• pp.680-687
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• 1996

Surgical removal of impacted mesiodens can be performed easily when exact position of mesiodens is identified. This case report is argued about methodological approach of exact antero-posterior postioning of mesiodens using conventional cross-sectional occlusal film and periapical film. The author concludes, 1. Among various methods of positioning mesiodens, exact position of mesiodens can be determined with occlusal film and periapical film. 2. On operation, exact antero-posterior position of mesiodens can be determined with comparing occlusal images of adjacent teeth and anatomic structure to real ones. 3. It is important that exact removal course of mesiodens has to be determined in addition to exact determination of one's position, and that it has to be determined in regard to position, morphological basis, direction of impacted pattern of mesiodens and adjacent anatomic structure. 4. In 2 cases presented, both are mesiodens of inverted conical type, and impacted direction are class I and III respectively according to classification author suggested, and surgery can be perfomed with ease by different approach directions.

• ETRI Journal
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• v.43 no.3
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• pp.483-510
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• 2021

In computational biology, desired patterns are searched in large text databases, and an exact match is preferable. Classical benchmark algorithms obtain competent solutions for pattern matching in O (N) time, whereas quantum algorithm design is based on Grover's method, which completes the search in $O(\sqrt{N})$ time. This paper briefly explains existing quantum algorithms and defines their processing limitations. Our initial work overcomes existing algorithmic constraints by proposing the quantum-based combined exact (QBCE) algorithm for the pattern-matching problem to process exact patterns. Next, quantum random access memory (QRAM) processing is discussed, and based on it, we propose the QRAM processing-based exact (QPBE) pattern-matching algorithm. We show that to find all t occurrences of a pattern, the best case time complexities of the QBCE and QPBE algorithms are $O(\sqrt{t})$ and $O(\sqrt{N})$, and the exceptional worst case is bounded by O (t) and O (N). Thus, the proposed quantum algorithms achieve computational speedup. Our work is proved mathematically and validated with simulation, and complexity analysis demonstrates that our quantum algorithms are better than existing pattern-matching methods.

• Advances in nano research
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• v.17 no.1
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• pp.19-32
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• 2024

Functionally graded-carbon nanotube (FG-CNT) is expected to be a new generation of materials with a wide range of potential applications in technological fields such as aerospace, defense, energy, and structural industries. In this paper, an exact finite strip method for functionally graded-carbon nanotube sandwich plates is developed using first-order shear deformation theory to get the exact natural frequencies of the plates. The face sheets of the plates are made of FG-CNT with continuous and smooth grading based on the power law index. The equations of motion have been generated based on the Hamilton principle. By extracting the exact stiffness matrix for any strip of the sandwich plate as a non-algebraic function of natural frequencies, it is possible to calculate the exact free vibration frequencies. The accuracy and efficiency of the current method is established by comparing its findings to the results of the literature works. Examples are presented to prove the efficiency of the generated method to deal with various problems, such as the influence of the length-to-height ratio, the power law index, and a core-to-face sheet thickness of the single and multi-span sandwich plates with various boundary conditions on the natural frequencies. The exact results obtained from this analysis can check the validity and accuracy of other numerical methods.

• Steel and Composite Structures
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• v.28 no.5
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• pp.589-606
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• 2018

The previous studies reflected the significant effect of neutral-axis position and coupling of in-plane and out-of-plane displacements on behavior of functionally graded (FG) nanobeams. In thin FG beam, this coupling can be eliminated by a proper choice of the reference axis. In shear deformable FG nanobeam, not only this coupling can't be eliminated but also the position of neutral-axis is dependent on through-thickness distribution of shear strain. For the first time, in this paper it is avoided to guess a shear strain shape function and the exact shape function and consequently the exact position of neutral axis for arbitrary gradation of higher order nanobeam are obtained. This paper presents new methodology based on differential transform and collocation methods to solve coupled partial differential equations of motion without any simplifications. Using exact position of neutral axis and higher order beam kinematics as well as satisfying equilibrium equations and traction-free conditions without shear correction factor requirement yields to better results in comparison to the previously published results in literature. The classical rule of mixture and Mori-Tanaka homogenization scheme are considered. The Eringen's nonlocal continuum theory is applied to capture the small scale effects. For the first time, the dependency of exact position of neutral axis on length to thickness ratio is investigated. The effects of small scale, length to thickness ratio, Poisson's ratio, inhomogeneity of materials and various end conditions on vibration and buckling of local and nonlocal FG beams are investigated. Moreover, the effect of axial load on natural frequencies of the first modes is examined. After degeneration of the governing equations, the exact new formulas for homogeneous nanobeams are computed.

• Progress in Medical Physics
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• v.27 no.2
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• pp.79-85
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• 2016

The objective of this study is to increase the accuracy of dose transmission in radiation therapy using two types of treatment tables, standard exact couch (Varian 21EX, Varian Medical Systems, Milpitas, CA) and 6D robotic couch (Novalis, BrainLAB A.G., Heimstetten, Germany)). We examined the dose attenuation based on the two types of treatment tables and studied the dose of attenuation using the phase (In/Out) for the standard exact couch. We measured the relative dose according to the incident angle of a penetrative photon beam under a treatment table. The incident angle of the photon beam was from $0^{\circ}$ to $360^{\circ}$ in the increments of $5^{\circ}$. The reference angle was set to $0^{\circ}$. Furthermore, the relative dose of the 6D robotic couch was measured using 6 MV and 15 MV, and that of the standard exact couch was measured at the sliding rail position (In-Out) using 6 MV and 10 MV. In the case of the standard exact couch, the measured relative dose was 16.53% (rails at the "In position," $175^{\circ}$, 6 MV), 12.42% (rails at the "In position," $175^{\circ}$, 10 MV), 13.13% (rails at the "Out position," $175^{\circ}$, 6 MV), and 9.96% (rails at the "Out position," $175^{\circ}$, 10 MV). In the case of the 6D robotic couch, the measured relative dose was 6.82% ($130^{\circ}$, 6 MV) and 4.92% ($130^{\circ}$, 15 MV). The photon energies were surveyed at the same incident angle. The dose attenuation for an energy of 10 MV was 4~5% lower than that for 6 MV. This indicated that the higher photon energy, lesser is the attenuation. The results of this study indicated that the attenuation rate for the 6D robotic couch was confirmed to be 1% larger than that for the standard exact couch at 6 MV and $180^{\circ}$. In the case of the standard exact couch, the dose attenuation was found to change rapidly in accordance with the phase ("In position" and "Out position") of the sliding rail.

• The Mathematical Education
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• v.24 no.1
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• pp.21-24
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• 1985

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1773-1783
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• 1996

Finite element method(FEM) is one of the most popularly used method analyzing the dynamic behaviors of structures. But unless number of finite elements is large enough, the results from FEM some what different from exact analytical solutions, especially at high frequency range. On the other hand, as the spectral analysis method(SAM) deals directly with the governing equations of a structure, the results from this melthod cannot but be exact regardless of any frequency range. However, the SAM can be applied only to the case where a structure is subjected to the concentrated loads, despite a structure could be unddergone distributed loads more generally. In this paper, therefore, new spectral analysis algorithm is introduced through the spectral element method(SEM), so that it can be applied to anlystructures whether they are subjected to the concentrated loads or to the distributed loads. The results from this new SEM are compared with both the results from FEM and the exact analytical solutions. As expected, the results from new SEM algorithm are found to be almost identical to the exact analytical solutions while those from FEM are not agreed well with the exact analytical solutions as the mode number increases.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.87-95
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• 2001

Although asymmetric beams are widely used in industry, few research results are available on the dynamic modeling and analysis of structure including asymmetric beams. Asymmetric beams cause complicated vibration phenomena due to the inherent bending-torsion coupled vibration. In this paper, an exact dynamic element matrix for the bending-torsion coupled vibration of asymmetric beam is derived. The application of the derived exact dynamic element matrix is demonstrated by some illustrative examples wherein the natural frequencies by the proposed modeling method are compared with those available in the literature. Another numerical example is also illustrated which deals with a general beam with joints. The numerical study shows that the exact dynamic element model is useful for the dynamic analysis of asymmetric bending-torsion coupled beams.

• Structural Engineering and Mechanics
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• v.35 no.2
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• pp.205-215
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• 2010

Recently, earthquake proof technology has been widely applied to both new and existing structures and bridges. The analysis of bridge systems equipped with structural control devices, which possess large degrees of freedom and nonlinear characteristics, is a result in time-consuming task. Therefore, a piecewise exact solution is proposed in this study to simplify the seismic mitigation analysis process for bridge systems equipped with sliding-type isolators. In this study, the simplified system having two degrees of freedom, to reasonably represent the large number of degrees of freedom of a bridge, and is modeled to obtain a piecewise exact solution for system responses during earthquakes. Simultaneously, we used the nonlinear finite element computer program to analyze the bridge responses and verify the accuracy of the proposed piecewise exact solution for bridge systems equipped with sliding-type isolators. The conclusions derived by comparing the results obtained from the piecewise exact solution and nonlinear finite element analysis reveal that the proposed solution not only simplifies the calculation process but also provides highly accurate seismic responses of isolated bridges under earthquakes.