• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.59-65
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• 2022

In this paper, a digital active phased array antenna is briefly introduced and beam forming method for a dual-channel side-lobe blanking applied to blank the side-lobe of the main beam is described. Next, the antenna performance was verified from results of design and antenna near-field measurement for the antenna main beam and side-lobe blanking beam. Then, a single-channel side-lobe blanking beam forming method was proposed to reduce the number of channels than the existing system operating dual-channel side-lobe blanking beam and weight distribution for each element of the side-lobe blanking antenna was designed with the proposed method. Finally, the designed single-channel side-lobe blanking beam pattern and blanking ability were verified and compared with the dual-channel side-lobe blanking beam. In addition, by comparing/verifying the conventional dual-channel and the proposed single-channel side-lobe blanking beam patterns measured through the receiving near-field test of the digital active phased array antenna and their ability to blank side-lobe of the main beam, validity of the proposed method for forming single-channel side-lobe blanking beam was confirmed.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.66-75
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• 2006

A modeling method for the modal analysis of rotating beam structures having complex configurations employing multi-reference frames is presented in the present study. In most structural analysis methods, single reference frame is employed for the modal analysis. For simple structures such as single beam or single plate, the method of employing single reference frame usually provides rapidly converging accurate results. However, for general structures having complex configurations, such a method provides slowly converging, and often erroneous, results. In the present study, the effects of employing multi-reference frames on the convergence and the accuracy of the modal analysis of rotating beam structures having complex configurations are investigated.

• Proceedings of the Acoustical Society of Korea Conference
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• 1984.12a
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• pp.33-35
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• 1984

A new type single beam photoacoustic spectrometer suitable for measuring optical absorption of condensed powder matter with the automatic calibration capability of a source power spectrum is introduced. The signal processing until of this spectrometer consists of a photoacoustic cell a lock-in amp., a switching circuit and a personal computer. The measured optical absorption spectra of a few material by this method are good agreement with the results obtained by the double-beam photoacoustic spectrometer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.389-392
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• 2008

This paper predicts the changes of natural frequencies due to the changes of mass at different point mass stations by using iterative calculation Transfer Matrices Method for different boundary conditions of a single beam structure (fixed-free and fixed-fixed beam). Firstly, the first three natural frequencies of an original beam are obtained using Transfer Matrices Method to verify the accuracy of the obtained results. The results are then compared with the exact solutions before purposely changing the parameter of mass. Both beams are modeled as discrete continuous systems with six-lumped-mass system. A single beam is broken down into a point mass and a massless beam which represent a single station and expressed in matrix form. The assembled matrices are used to determine the value of natural frequencies using numerical interpolation method corresponding to their mode number by manipulating some elements in the assembled matrix.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.5
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• pp.798-807
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• 2021

The directivity characteristics of acoustic transducers for conventional single-beam echo sounders considerably limit the detection of fish-size information in acoustic field surveys. To overcome this limitation, using the split-aperture technique to estimate the direction of arrival of single-echo signals from individual fish distributed within the sound beam represents the most reliable method for fish-size classification. For this purpose, we design and develop a split-beam data acquisition and processing system to obtain fish-size information in conjunction with a 50-kHz single-beam echo sounder. This split-beam data acquisition and processing system consists of a notebook PC, a field-programmable gate array board, an external single-transmitter module with a matching network, and four-channel receiver modules operating at a frequency of 50-kHz. The functionality of the developed split-beam data processor is tested and evaluated. Acoustic measurements in an experimental water tank showed that the developed data acquisition and processing system can be used as a fish-sizing echo sounder to estimate the size distribution of individual fish, although an external single-transmitter module with a matching network is required.

• Structural Engineering and Mechanics
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• v.4 no.6
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• pp.613-630
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• 1996

The homogenization method is used to develop a beam element in space for thermo-mechanical analysis of unidirectional composites. Local stress and temperature field in the microscale are described using the function of homogenization. The global (macroscopic) behaviour of the structure is supposed to be that of a beam. Beam-type kinematical hypotheses (including independent shear rotations) are hence applied and superposed on the microdescription. A macroscopic stiffness matrix for such a beam element is then developed which contains the microscale properties of the single cell of periodicity. The presented model enables us to analyse without too much computational effort complicated composite structures such as e.g. toroidal coils of a fusion reactor. We need only a FE mesh sufficiently fine for a correct description of the local geometry of a single cell and a few of the newly developed elements for the description of the global behaviour. An unsmearing procedure gives the stress and temperature field in the different materials of a single cell.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.3
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• pp.209-216
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• 2008

The application of focused ion beam (FIB) depends on the optimal interaction of the operation parameters between operating parameters which control beam and samples on the stage during the FIB deposition process. This deposition process was investigated systematically in C precursor gas. Under the fine beam conditions (30kV, 40nm beam size, etc), the effect of considered process parameters - dwell time, beam overlap, incident beam angle to tilted surface, minimum frame time and pattern size were investigated from deposition results by the design of experiment. For the process analysis, influence of the parameters on FIB-CVD process was examined with respect to dimensions and constructed shapes of single and multi- patterns. Throughout the single patterning process, optimal conditions were selected. Multi-patterning deposition were presented to show the effect of on-stage parameters. The analysis have provided the sequent beam scan method and the aspect-ratio had the most significant influence for the multi-patterning deposition in the FIB processing. The bitmapped scan method was more efficient than the one-by-one scan type method for obtaining high aspect-ratio (Width/Height > 1) patterns.

• Journal of information and communication convergence engineering
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• v.19 no.2
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• pp.108-113
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• 2021

Multiview autostereoscopic three-dimensional (MA3D) displays have the disadvantage that the single-view resolution decreases as the number of views increases. Furthermore, the resolution of MA3D displays is relatively degraded, even though the resolution of two-dimensional displays has increased recently. Therefore, it is unattractive to consumers, and the single-view resolution enhancement of MA3D displays is required. In this study, we developed a method for supplementing the single-view resolution of MA3D displays using a plate beam splitter that can show two MA3D displays simultaneously. By applying our proposed method, the resolution of a single view can increase, and the visual obstruction by the optical plate, which is a problem for MA3D displays, can be solved. In addition, an MA3D display was optically designed and fabricated using a parallax barrier. Finally, the experimental optical results obtained using the proposed method and the only MA3D display were compared.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.255-256
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• 2007

We propose a novel method for the beam focusing by a single subwavelength metal slit surrounded by chirped dielectric surface gratings. In the proposed method, the period of each grating is chirped to make a focused beam at the desired position. Design of the grating structures for optimal beam focusing and the analysis of the field distribution are conducted based on the rigorous coupled wave analysis (RCWA). It is shown that the focused beam is formed at 1.5${\mu}m$ from the metal substrate and its full width at half maximum (FWHM) is 411nm.

• Steel and Composite Structures
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• v.18 no.4
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• pp.853-871
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• 2015

Up to now, Japan has more than 200 corrugated steel web composite beam bridges which are under construction and have been constructed, and China has more than 30 corrugated steel web composite beam bridges. The bridge type includes the simply supported beam, continuous beam, continuous rigid frame and cable stayed bridge etc. The section form has developed to the single box and multi-cell box girder from the original single box and single chamber. From the stress performance and cost saving, the span range of 50~150 m is the most competitive. At present, the design mostly adopts the computational analytical method combining the spatial bar system model, plane beam grillage model and solid model. However, the spatial bar system model is short of the refinement analysis on the space effect, such as the shear lag effect, effective distribution width problem, and eccentric load factor problem etc. Due to the similarity of the plane beam grillage method in the equivalence principle, it cannot accurately reflect the shearing stress distribution and local stress of the top and bottom plates of the box type composite beam. The solid model is very difficult to combine with the overall calculation. Moreover, the spatial grid model can achieve the refinement analysis, with the integrity of the analysis and the comprehensiveness of the stress checking calculation, and can make up the deficiency of the analytical method currently. Through the example verification of the solid model and spatial grid model, it can be seen that the calculation results for the stress and the displacement of two models are almost consistent, indicating the applicability and precision of the spatial grid model.