• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.1
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• pp.21-28
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• 2005

In this paper, we studied resolution to the FBP(Filtered Back-Propagation) tomographic image reconstruction algorithms. In order to analyze the resolution to the tomographic images, we derived ambiguity function to this algorithm which can be reconstructed from the improved FBP image reconstruction algorithm by using fixed coordinate system practically. Through simulation using this function, we determined the lateral and depth resolution quantitively and then analyzed respectively. Simulation results show that the lateral and depth resolution to the improved FBP image reconstruction algerian was determined $0.27\lambda\;and\;0.70\lambda$ at the 3dB, and also $0.89\lambda\;and\;0.96\lambda$ at the 6dB respectively. This results proved that improved FBP reconstruction algorithms for diffraction tomography of incident planar wave is useful to developed the tomographic image system, analyze the resolution to the tomographic images, we derived ambiguity function to this algerian which can be reconstructed from the improved FBP image reconstruction algorithm by using fixed coordinate system.

• Journal of ILASS-Korea
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• v.7 no.4
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• pp.9-15
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• 2002

Convolution Fourier transformation tomographically reconstructs the spatially resolved spray injection rate from direct measuring cells. Asymmetric sprays generated from a twin-hole air shroud injector are tested with 12 equiangular projections of measurements. For each projection angle, line of sight integrated injection rate was measured at 35 positions with equal spacing measuring cells of 3 mm in width, 100 mm in length, 55 mm in depth and 0.5 mm thickness of separating wall. Interpolated data between the projection angles effectively increase the number of projections, which significantly enhances the signal-to-noise level in the reconstructed data. This modified convolution Fourier transformation scheme predicts well the structure of asymmetric sprays. Comparative study has been made between sprays with and without air shrouding. Tomograhpic reconstruction of injection rate from direct measuring cells obtained can be used to estimate the accuracy of volume fraction of spray from the LDPA tomographic reconstruction.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11b
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• pp.126-140
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• 2005

The tomographic gamma scanner (TGS) method, a further of extension of segmented gamma scanner (SGS), is most accurate and precise for assaying heterogeneous drummed nuclear radioactive waste; it is widely used in nuclear power plants and radioactive waste storages and disposal sites. The transmission and emission images are reconstructed by image reconstruction techniques. In the paper, the principle of TGS is introduced; image reconstruction techniques are discussed as well; finally, it is demonstrated that TGS method performance.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.55-61
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• 1999

A convolution algorithm combined with Fourier transformation is applied to the tomographic reconstruction of the asymmetric soot structure to identify the local soot volume fraction distribution. The line of sight integrated data from light extinction measurement with multi-angular scanning form basic information for the deconvolution. Multi-peak following interpolation technique is applied to obtain the effect of increasing number of scanning angles. Measurement of LII signal for the same flame shows the validity of this reconstruction technigue.

• The Journal of the Acoustical Society of Korea
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• v.15 no.1E
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• pp.70-76
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• 1996

We proposed to use shear waves instead of longitudinal waves in a STAM (scanning tomographic acoustic microscope system) in which the specimens are solid. For any specimen with a shear modulus, mode conversion will take place at the water-solid interface. Some of the energy of the insonifying longitudinal waves in the water will convert to shear wave energy within the specimen. The shear wave energy is detectable and can be used for tomographic reconstruction. The resolution limitation of STAM depends on the available angular view and the acoustic wavelength. While wave transmission in most solid specimens is limited to about 20°for longitudinal waves, we show that it is about twice that high for shear waves. Since the wavelength of the shear wave is shorter than that of the longitudinal wave, we are able to achieve the high resolution. In order to compare the operation of a shear-wave STAM with that of the conventional longitudinal-wave STAM we have simulated tomographic reconstruction for each. Our simulation results with aluminum specimen and back-and-forth propagation algorithm showed resolution of a shear-wave STAM is better than that of a longitudinal-wave STAM.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.279-282
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• 1997

Bayesian reconstruction methods for emission computed tomography have been a topic of interest in recent years, partly because they allow for the introduction of prior information into the reconstruction problem. Early formulations incorporated priors that imposed simple spatial smoothness constraints on the underlying object using Gibbs priors in the form of four-nearest or eight-nearest neighbors. While these types of priors, known as "membrane" priors, are useful as stabilizers in otherwise unstable ML-EM reconstructions, more sophisticated prior models are needed to model underlying source distributions more accurately. In this work, we investigate whether the "thin plate" model has advantages over the simple Gibbs smoothing priors mentioned above. To test and compare quantitative performance of the reconstruction algorithms, we use Monte Carlo noise trials and calculate bias and variance images of reconstruction estimates. The conclusion is that the thin plate prior outperforms the membrane prior in terms of bias and variance.

• Journal of the Korean Society of Combustion
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• v.8 no.3
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• pp.24-30
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• 2003

A convolution algorithm combined with Fourier transformation has been applied to the tomographic reconstruction of asymmetric soot structure to identify the local soot volume fraction distribution. Line-of-sight integrated data from light extinction measurement with multi-angular scanning formed basic information for the deconvolution. Multi-peak following interpolation technique was applied to obtain the effect of increasing number of scanning angles. Height-by-height reconstructed soot volume fraction distribution was compared with laser-induced incandescence signals.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.177-186
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• 1996

A convolution alogorithm combined with Fourier transformation is applied to the tomographic reconstruction of the asymmetric spray structure to identify the local drop size and volume concentration. The line of sight intergrated data from Malvern particle analyzer with multiangular scanning form a basic information for the deconvolution. Linear interpolation is tested to obtain the effect of increasing number of scanning angles. This transformation method predicts well the structure of asymmetric spray. The tehnique can be extended to other line of sight combustion diagnostics.

• The Journal of the Acoustical Society of Korea
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• v.18 no.5
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• pp.83-90
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• 1999

In this paper, we studied resolution to the FBP and BFP image reconstruction algorithms for ultrasonic diffraction tomography. In order to analyze the resolution to the tomographic images which can be reconstructed from the modified FBP image reconstruction algorithm by using fixed coordinate system and BFP image reconstruction algorithm which is suitable for plane structure object, we derived ambiguity functions to these algorithms and then analyzed lateral and depth resolution through simulation respectively. Simulation results show that the lateral and depth resolution to the FBP image reconstruction algorithm and the BFP image reconstruction algorithm was determined 0.27 λ, 0.70 λ and 0.39 λ, 0.98 λ at the 3dB respectively. These results imply that modified FBP and BFP image reconstruction algorithms for diffraction tomography is useful in the tomographic image reconstruction.

• Archives of Reconstructive Microsurgery
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• v.22 no.2
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• pp.43-47
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• 2013

Purpose: Un-healing and centrally located defect on back area, it is sometimes a challenge for the reconstructive surgeon. Although skin grafts are considered as the first choice for reconstruction of large skin defect on the back region, it is not always helpful but vascularized flaps provide a superior functional and aesthetic outcome. The present study was designed to investigate the clinical anatomy of the lumbar artery perforator flap to reconstruct back ulcer. Materials and Methods: Clinical anatomy study was undertaken using computed tomographic angiographic analysis. We identified the courses of lumbar arteries and its perforators, measured pedicle length by layers. The location of the perforator vessel was charted against anatomical landmarks. Results: The pedicle lengths of the third and fourth lumbar artery perforator reached a mean of 27.8 mm and 37.1 mm respectively from superficial fascia to deep fascia. The fourth perforator was more laterally located than the third perforator and less than 1 cm above the iliac crest. A case in which the fourth lumbar artery perforator was used as flap pedicle is described. Conclusion: For the reconstruction of central defect on the back area, the lumbar artery perforator flap coverage may be a good alternative option. Computed tomographic angiography can easily identify the course and location of lumbar artery perforators and can be helpful to elevate the flap successfully.