• International Journal of Precision Engineering and Manufacturing
• /
• v.9 no.4
• /
• pp.45-50
• /
• 2008

The Fourier-Mellin transform is the theoretical basis for the translation, rotation, and scale invariance of an image. However, its implementation requires a log-polar map of the original image, which requires logarithmic sampling of a radial variable in that image. This means that the mapping process is accompanied by considerable loss of data. To solve this problem, we propose a dual log-polar map that uses both a forward image map and a reverse image map simultaneously. Data loss due to the forward map sub-sampling can be offset by the reverse map. This is the first step in creating an invertible log-polar map. Experimental results have demonstrated the effectiveness of the proposed scheme.

• The Korean Journal of Nuclear Medicine
• /
• v.27 no.1
• /
• pp.51-58
• /
• 1993

We have anlayzed the polar maps of dipyridamole stress/rest $^{99m}Tc$-MIBI SPECT and compared the quantitated perfusion defects of dipyridamole stress polar map and the findings of coronary angiography in 56 pateints with coronary artery diseases. We performed the same day dipyridamole stress-rest myocardial SPECT, reconstructed the polar maps according to Cedars-Sinai method and quantitated perfusion detects of total myocardium and the territory of each artery, comparing the polar maps of patients with normal files. Stenosis more than 50 percent was considered significant and myocardial ischemic score was calculated as summed score of percents of main coronary arteries. Positive concordance of myocardial SPECT with coronary angiography were 82.6% with left anterior descending artery (LAD), 85.7% with left circumflex artery (LCx) and 78.6% with right coronary artery (RCA). Perfusion defect of SPECT polar map and the stenosis of coronary artery showed the contingency phi of 0.55 (p<0.0001) with total atreries, 0.38 (p = 0.016) with LAD, 0.50 (p<0.0001) with LCx and 0.40 (p = 0.007) with RCA. Dipyridamole stress percent defect of polar map was correlated with myocardial ischemic score with Spearman's rho of 0.47 (p = 0.001) in total arteries, 0.48 (p=0.001) in LAD, 0.56 (p < 0.001) in LCx and 0.38 (p=0.002) in RCA. These findings revealed that defect of the dipyridamole stress myocardial $^{99m}Tc$-MIBI SPECT and the percent extent of this defect were related with significant artery stenosis of individual arteries and the degree of stenosis. We thought that we could use the defects in the polar map of dipyridamole stress $^{99m}Tc$-MIBI SPECT for the quantification of myocardiasl perfusion decrease.

• Journal of the Institute of Convergence Signal Processing
• /
• v.6 no.1
• /
• pp.15-22
• /
• 2005

In this paper, we propose a face recognition system by using the CCD color image. We first get the face candidate image by using YCbCr color model and adaptive skin color information. And we use it initial curve of active contour model to extract face region. We use the Eye map and mouth map using color information for extracting facial feature from the face image. To obtain center point of Log-polar image, we use extracted facial feature from the face image. In order to obtain feature vectors, we use extracted coefficients from DCT and wavelet transform. To show the validity of the proposed method, we performed a face recognition using neural network with BP learning algorithm. Experimental results show that the proposed method is robuster with higher recogntion rate than the conventional method for the rotation and scale variant.

• The Journal of the Korea Contents Association
• /
• v.5 no.1
• /
• pp.127-134
• /
• 2005

To connect the gap on the contours at the summit area, we propose the linear interpolation in the polar coordinates. Tn the experiments of applying both existing algorithms and a proposed method to some graphic images, the proposed method generated curves that average MAE was 1.940 pixels. In particular, our method with MAE of 1.240 on real map image was superior than the others. Also by generating new curves with neighbors-resembled appearance, the contours were reconstructed seamlessly.

• Proceedings of the KIEE Conference
• /
• 2003.11b
• /
• pp.23-26
• /
• 2003

The vector field histogram(VFH) uses a two-dimensional Cartesian histogram grid as a world model. The VFH method subsequently employs a two-stage data-reduction process in order to compute the desired control commands for the vehicle. In the first stage the histogram grid is reduced to a one dimensional polar histogram that is constructed around the robot's momentary location. Each sector in the polar histogram contains a value representing the polar obstacle density in that direction. In the second stage, the algorithm selects the most suitable sector from among all polar histogram sectors with a low polar obstacle density, and the steering of the robot is aligned with that direction. We applied this algorithm to our four-legged robot.

• Bulletin of the Korean Chemical Society
• /
• v.13 no.3
• /
• pp.268-274
• /
• 1992

An attempt to improve the second harmonic generation (SHG) efficiency of MAP (methyl (2,4-dinitrophenyl)aminopropanoate) by modifying the substituents on the amino group of MAP is described. Several MAP analogues have been prepared using optically active amino acids alanine, phenylalanine and serine, and their SHG efficiencies measured. None of the MAP analogues exhibited SHG efficiencies as high as that of MAP. X-ray crystal structures of three MAP analogues have been determined. In the crystal structures of two of them, which were the derivatives of phenylalanine, two crystallographically-independent molecules existing in the asymmetric unit are aligned almost antiparallel. These structures are consistent with the very low SHG efficiencies of these compounds. On the other hand, the crystal structure of a serine derivative reveals substantial alignment of the dinitroaniline chromophore along the polar axis. However, the angle of 86.2° between the molecular charge tranfer axis and the polar axis of the crystal is still far away from the optimum value of 54.74° for the phase-matchable SHG. The structure is consistent with the SHG efficiency of this compound which is much higher than those of the phenylalanine derivatives but still lower than that of MAP. This study demonstrates the importance of the orientation of molecules in the crystal lattice in determining secod-order nonlinear optical properties of crystalline materials.

• Journal of The Korean Astronomical Society
• /
• v.29 no.spc1
• /
• pp.433-437
• /
• 1996

We have analyzed the content of the Korean stone star chart. Ch'on-Sang-Yul-Cha-Bun-Ya-Ji-Do(here-after Ch'on-Sang-Do). In the star map we have found 1468 stars, 4 more than the Chinese star catalog Bo-Chun-Ga. The four extra stars form a constellation, Jong Dae Boo. The map projection law used in the star chart is found to be the polar equtorial and equidistance projection. The linear distance of an object on Ch'on-Sang-Do from the center is linearly proportional to the north polar angular distance. We have found from a statistical analysis that most stars with declination lower than 50 are at positions representing the epoch of around the first century. On the other hand, stars near the north pole with declination higher than 50 are at the epoch of about 1300, which is close to the time the chart was engraved. This implies that the original Ko-Gu-Rye Dynasty's star chart has been revised by astronomers of Cho-Sun Dynasty. We have also shown that stars on Ch'on-Sang-Do are engraved in such a way that their area is linearly proportional to the visual magnitude.

• Bulletin of the Korean Mathematical Society
• /
• v.47 no.1
• /
• pp.211-219
• /
• 2010

Let P be a Jacobian polynomial such as deg P = $deg_y$ P. Suppose the Jacobian polynomial P satisfies the intersection condition satisfying $dim_C$ C[x, y]/$P_y$> = deg P - 1, we can prove that the Keller map which has P as one of coordinate polynomial always has its inverse.

• Progress in Medical Physics
• /
• v.22 no.1
• /
• pp.42-51
• /
• 2011

Nuclear medicine images (SPECT, PET) were widely used tool for assessment of myocardial viability and perfusion. However it had difficult to define accurate myocardial infarct region. The purpose of this study was to investigate methodological approach for automatic measurement of rat myocardial infarct size using polar map with adaptive threshold. Rat myocardial infarction model was induced by ligation of the left circumflex artery. PET images were obtained after intravenous injection of 37 MBq $^{18}F$-FDG. After 60 min uptake, each animal was scanned for 20 min with ECG gating. PET data were reconstructed using ordered subset expectation maximization (OSEM) 2D. To automatically make the myocardial contour and generate polar map, we used QGS software (Cedars-Sinai Medical Center). The reference infarct size was defined by infarction area percentage of the total left myocardium using TTC staining. We used three threshold methods (predefined threshold, Otsu and Multi Gaussian mixture model; MGMM). Predefined threshold method was commonly used in other studies. We applied threshold value form 10% to 90% in step of 10%. Otsu algorithm calculated threshold with the maximum between class variance. MGMM method estimated the distribution of image intensity using multiple Gaussian mixture models (MGMM2, ${\cdots}$ MGMM5) and calculated adaptive threshold. The infarct size in polar map was calculated as the percentage of lower threshold area in polar map from the total polar map area. The measured infarct size using different threshold methods was evaluated by comparison with reference infarct size. The mean difference between with polar map defect size by predefined thresholds (20%, 30%, and 40%) and reference infarct size were $7.04{\pm}3.44%$, $3.87{\pm}2.09%$ and $2.15{\pm}2.07%$, respectively. Otsu verse reference infarct size was $3.56{\pm}4.16%$. MGMM methods verse reference infarct size was $2.29{\pm}1.94%$. The predefined threshold (30%) showed the smallest mean difference with reference infarct size. However, MGMM was more accurate than predefined threshold in under 10% reference infarct size case (MGMM: 0.006%, predefined threshold: 0.59%). In this study, we was to evaluate myocardial infarct size in polar map using multiple Gaussian mixture model. MGMM method was provide adaptive threshold in each subject and will be a useful for automatic measurement of infarct size.

• Korean Journal of Animal Reproduction
• /
• v.22 no.3
• /
• pp.265-276
• /
• 1998

In an attempt to evaluate the function of MAP kinase of porcine oocytes and to develop a method of assessment for kinase activity, we used MBP as a substrate to detect the MAP kinase activity of porcine oocytes matured in in vitro. The MAP kinase which had lower activity during the first 20 hours of culture started to show an increased amount of activity at 25 hours at which a collapse in nuclear membrane was induced. Significant (P<0.05) a, pp.ared at 30 hours of being cultured. The gel phosphorylation method, MBP which has been known to be a substrate for kinase such as cdc2 kinase, was phosphorylated at two positions corresponding to ERK 1 (44kDa) and ERK2 (42 kDa) which are known as mammalian MAP kinase. The existence of MARKK and MAP kinase were identified with western blotting at 0 hour culture of immature GV oocytes. The amount of those proteins did not increase during 40 hours of culture, which suggest that the increase of MAP kinase activity was caused by phosphorylaton rather than due to change in protein amount. MAPKK and MAP kinase were shown to be dephosporylated with deactivated at M 1 stage by inhibition of protein synthesis with cycloheximide added at the strat following the cultrue. We have reulsts that indicate the existedence of MAP kinase cascade which was activated simultaneously with start of porcine oocyte maturation (GVBD).