• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.395-407
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• 2021

The effect of the specifications of a silicon-on-insulator vertical slot optical waveguide on the sensitivity of homogeneous and surface sensing configurations for TE and TM polarization, respectively, was systematically analyzed using numerical software. The specifications were optimized based on the confinement factor and transmission power of the TE-guided mode distributed in the slot. The waveguide sensitivities of homogeneous and surface sensing were calculated according to the specifications of the optimized slot optical waveguide.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.25-30
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• 2018

Closed-form analytical expressions and 3-dimensional normalized charts for the homogeneous sensing and surface sensing structures are derived to provide the conditions for the maximum sensitivity of integrated-optic biosensors based on evanescent-wave and stepindex planar optical waveguides. The analysis is made for transverse electric (TE) polarization mode, in both cases where the measurand is homogeneously distributed in the cover (namely, homogeneous sensing), and where it is an ultrathin film on the waveguide-cover interface (namely, surface sensing).

• Journal of Sensor Science and Technology
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• v.17 no.5
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• pp.361-368
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• 2008

Nanosized $SnO_2$ particles were synthesized by homogeneous precipitation method using tin chloride ($SnCl_4{\cdot}5H_{2}O$) and urea ($CO(NH_2)_2$). The powders were heated at $500^{\circ}C$ and $600^{\circ}C$ for 2h. The crystal structure, microstructure, thermal behavior, specific surface area were analyzed using XRD, FE-SEM, TGA and BET, respectively. The initial resistance and the $H_2$ sensing properties were measured as a function of ${Sb_2}{O_3}$ and Pd doping concentrations. The resistance was decreased with the addition of ${Sb_2}{O_3}$ and the sensitivity for $H_2$ gas was increased with the addition of Pd. Thus, the optimum $H_2$ gas sensing property was obtained in the 0.25.mol% ${Sb_2}{O_3}$ and 1.w% added $SnO_2$ powders.

• Journal of Sensor Science and Technology
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• v.32 no.4
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• pp.223-231
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• 2023

An integrated-optical biochemical sensor structure that can perform homogeneous and surface sensing using a 2×2 balanced-bridge Mach-Zehnder interference structure based on the optimized SOI slot optical waveguide was described, and its performance and characteristics were evaluated. Equations for the two output optical powers were derived and examined using the transfer matrices of a 3-dB coupler and phase shifter (channel waveguide). The length of the 3-dB coupler was determined such that the two output optical powers were same using these formulas. In homogeneous sensing, the effect of the refractive index of an analyte in the range of 1.33-1.36 on the two output optical power distributions was numerically derived, and the sensitivity was calculated based on each output and the difference between the two outputs, the former and the latter being 7.5796-19.0305 [au/RIU] and 15.2601-38.1351 [au/RIU], respectively. In the case of surface sensing, the sensitivity range of the refractive index of 1.337 based on each of the two outputs was calculated as -2.2490--3.5854 [au/RIU] and 1.2194-3.8012 [au/RIU], and the sensitivity range of 4.8048-7.0694 [au/RIU] was confirmed based on the difference between the two outputs.

• Korean Journal of Remote Sensing
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• v.18 no.3
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• pp.181-186
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• 2002

One of the most important procedure in stereo DEM generation is the stereo matching process which finds the conjugate pixels in a pair of stereo imagery. In order to be found as conjugate pixels, the pixels should have distinct spatial feature to be distinguished from other pixels. However, in the homogeneous areas such as water covered or forest canopied areas, it is very difficult to find the conjugate pixels due to the lack of distinct spatial feature. Most of erroneous elevation values in the stereo DEM are produced in those homogeneous areas. This paper presents a simple method for improving the quality of stereo DEM utilizing the texture filters. An entropy filter was applied to one of the input stereo imagery to extract very homogeneous areas before stereo matching process. Those extracted homogeneous areas were excluded from being candidates for stereo matching process. Also a statistical texture filter was applied to the generated elevation values before the interpolation process was applied in odor to remove the remaining anomalous elevation values. Stereo pair of SPOT level 1B panchromatic imagery were used for the experiments. The results showed that by utilizing the texture filters as a pre and a post processor of stereo matching process, the quality of the stereo DEM could be dramatically improved.

• Bulletin of the Korean Mathematical Society
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• v.61 no.2
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• pp.479-488
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• 2024

Convergence to a steady state in the long term limit is established for global weak solutions to a chemotaxis model with degenerate local sensing and consumption, when the motility function is C¹-smooth on [0, ∞), vanishes at zero, and is positive on (0, ∞). A condition excluding that the large time limit is spatially homogeneous is also provided. These results extend previous ones derived for motility functions vanishing algebraically at zero and rely on a completely different approach.

• The Journal of the Acoustical Society of Korea
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• v.37 no.1
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• pp.73-81
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• 2018

The quality of side scan sonar images is determined by the frequency of a sonar. A side scan sonar with a low frequency creates low-quality images. One of the factors that lead to low quality is a high-level noise. The noise is occurred by the underwater environment such as equipment noise, signal interference and so on. In addition, in order to compensate for the transmission loss of sonar signals, the received signal is recovered by TVG (Time-Varied Gain), and consequently the side scan sonar images contain non-homogeneous noise which is opposite to optic images whose noise is assumed as homogeneous noise. In this paper, the SSCS (Structural Sparsity based Compressive Sensing) is proposed for removing non-homogeneous noise. The algorithm incorporates both local and non-local models in a structural feature domain so that it guarantees the sparsity and enhances the property of non-local self-similarity. Moreover, the non-local model is corrected in consideration of non-homogeneity of noises. Various experimental results show that the proposed algorithm is superior to existing method.

• Korean Journal of Remote Sensing
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• v.25 no.1
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• pp.21-30
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• 2009

The purposes of this paper are to present a selection method of neighboring pixels whose local statistics are similar to the center pixel and combine the selection result with mean curvature diffusion filter to reduce noises in remote sensed imagery. The order of selection of neighboring pixels is critical, especially for finding a pixel belonging to the homogeneous region, since the statistics of the homogeneous region vary according to the selection order. An effective strategy for selecting neighboring pixels, which uses rank-order differences vector obtained by computing the intensity differences between the center pixel and neighboring pixels and arranging them in ascending order, is proposed in this paper. By using region growing method, we divide the elements of the rank-ordered differences vector into two groups, homogeneous rank-ordered differences vector and outlier rank-ordered differences vector. The mean curvature diffusion filter is combined with a line process, which chooses selectively diffusion coefficient of the neighboring pixels belonging into homogeneous rank-ordered differences vector. Experimental results using an aerial image and a TerraSAR-X satellite image showed that the proposed method reduced more efficiently noises than some conventional adaptive filters using all neighboring pixels in updating the center pixel.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.192-194
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• 2003

Since the details in quasi-homogeneous region will be destroyed from the conventional global image enhancement method such as histogram equalization. This defect is caused by the saturation of gray level in equalization process. So the local histogram equalization for each quasi-homogeneous region will be used in order to improve the details in the region itself. To obtain the quasi- homogeneous regions, the original image must be segmented. Here we applied the watershed transform to the interesting image. Since the watershed transform is based on mathematical morphology, therefore, the regions touch can be effectively separated. Hence two adjacent regions which have the similar gray pixels will be split off. The process will be independently applied to three different spectral images. Then three different colors are assigned to each processed image in order to produce a color composite image. By the proposed algorithm, the result image shows the better perception on image details. Therefore, the high efficiency of image classification can be obtained by using this color image.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1017-1021
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• 1995

Geometric and thermal errors are responsible for major components of the errors of a computer numerically controlled turning center. The planar error of a CNC turning center are comprised of 11 geometric and thermal error components. The error synthesis model is formulated by homogeneous coordinate transformation method and expresses the effect of such error components on the planar error of a CNC turning center. In this paper, the sensitivity analysis of the model on the noises through sensing and the change of temperature is addressed. The sensitivity analysis show that the error systhesis model is robust on the noses and z planar error is much affected by the change of temperatures.