• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.3
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• pp.1-11
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• 1999

It is now common practice to utilize the quadrature RF coils to improve the signal-to-noise ratio (SNR) in the Magnetic Resonance Imaging (MRI) System. In addition, to make such an available SNR improvement, it is mandatory to use a well-designed quadrature coupler, which facilitates a perfect 3-dB coupling and quadrature-phase shift. However, the four ports matching condition has to be well considered during the RF excitation and the signal detection period. This work investigates the effects of such a mismatching condition (especially, due to patient) from the analysis, simulation, and real implementation and firstly proposes dynamic loading technique for a quadrature coupler and transmitting/receiving switch module to minimize a patient mismatching and enhance a system reliability. Also, we designed and implemented the quadrature coupler and transmitting/receiving switch module using microstrip. As a result, the SNR of our MRI system using the microstrip quadrature coupler and transmitting/receiving switch module with dynamic load increases 3 dB compared with the old one using USA quadrature switch. Also, the power capability of quadrature coupler and transmitting/receiving switch module is 5-kw peak power. Considering power loss and reduction of size, we used a RT/duroid 6010 substrate with high permittivity and for simulation we use Compact Software.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.418-428
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• 2003

Fiber fracture is one of the dominant failure phenomena affecting the total mechanical Performance of the composites. Fiber fracture locations were measured through the conventional optical microscope and the nondestructive acoustic emission (AE) technique and then were compared together as a function of the epoxy matrix modulus and the fiber surface treatment by the electrodeposition method (ED). Interfacial shear strength (IFSS) was measured using tensile fragmentation test in combination of AE method. ED treatment of the fiber surface enlarged the number of fiber fracture locations in comparison to the untreated case. The number of fiber fracture events measured by the AE method was less than optically obtained one. However, fiber fracture locations determined by AE detection corresponded with those by optical observation with small errors. The source location of fiber breaks by AE analysis could be a nondestructive, valuable method to measure interfacial shear strength (IFSS) of matrix in non-, semi- and/or transparent polymer composites.

• Journal of Animal Science and Technology
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• v.46 no.3
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• pp.315-324
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• 2004

Cytochrome P450 aromatase is the enzyme responsible for biosynthesis of female sex hormone(estrogen) and 19-nortestosterone(nandrolone), a unique steroid hormone endogenously synthesized in the pig. By use of RT-PCR coupled with DHPLC technique (WAVE analysis), expression pattern of isoforms of porcine cytochrome P450 aromatase gene was investigated. Relatively higher expression of aromatase mRNA was observed in testis than in ovary and this result accounted for the previous findings of higher blood estrogen level in male compared with female in this species. The result from the DHPLC demonstrated that PCR amplified DNA fragments of ovary and testis tissues. using unique PCR primers for all three types of aromatase genes, were different from those of type II and ill genes. Further nucleotide sequence analyses of the plasmid clones containing the PCR products revealed that nucleotide sequences of all clones were identical to type I aromatase gene(ovary type). Thus, the result from the present study indicates that the ovary and testis express the same type of aromatase gene. Therefore, the efficacy of DHPLC techniques used for this study helped us to analyze tissue-specific expression of isoform of genes containing the nucleotide sequences with high homology.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.61-67
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• 2015

Recently, the initiation of outside diameter stress corrosion cracking (ODSCC) at the tube support plate region of domestic steam generators (SG) with Alloy600 HTMA tubes has been increasing. As a result, SGs with Alloy600 HTMA tubes must be replaced early or are scheduled to be replaced prior to their designed lifetime. ODSCC is one of the biggest threats to the integrity of SG tubes. Therefore, the accurate evaluation of tube integrity to determine ODSCC is needed. Eddy current testing (ECT) is conducted periodically, and its results could be input as parameters for evaluating the integrity of SG tubes. The reliability of an ECT inspection system depends on the performance of the inspection technique and abilty of the analyst. The detection probability and ECT sizing error of degradation are considered to be the performance indices of a nondestructive evaluation (NDE) system. This paper introduces an optimized evaluation method for ECT, as well as the sizing error, including the analyst performance. This study was based on the results of a round robin program in which 10 inspection analysts from 5 different companies participated. The analysis of ECT sizing results was performed using a linear regression model relating the true defect size data to the measured ECT size data.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.13-25
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• 1999

P. endodontalis which was known to be associated with the infected root canals and periapical lesions is very difficult to detect by culture methods or traditional methods. Detection of bacteria using polymerase chain reaction(PCR) for 16S ribosomal DNA(rDNA) is fast, simple, and accurate with relatively small amount of target cells. 16S rDNA consist of conserved regions those are same to all species, and variable regions which represent species specificity. The 16S rDNA sequences of P. endodontalis and P. gingivalis were aligned and two highly variable regions were selected as a pair of species specific oligonucleotide primers for P. endodontalis. And then the pair of primers for PCR amplification was synthesized to identify P. endodontalis. The sequences of the species specific primers for the 16S rDNA of P. endodontalis were as follows ; sense primer[endo1]: 5'-CTATATTCTTCTTTCTCCGCATGGAGGAGG-3' antisense primer[endo2]: 5'-GCATACCTTCGGTCTCCTCTAGCATAT-3' In this study, for the identification of P. endodontalis without culture from the mixed clinical samples, PCR was done with species specific primers for the 16S rDNA sequences of P. endodontalis. The results were as follows : 1. The species specificity of the primers for the 16S rDNA of P. endodntalis was determined by the PCR methods. About 490bp amplicon which was specific only for P. endodntalis was produced with P. endodontalis. No amplicon was produced by PCR with other strains similar to P. endodontalis. 2. The synthesized species specific primers reacted with conventionally identified P. endodontalis which we have in conservative dentistry laboratory. 3. The identification of P. endodontalis using PCR technique with samples collected from infected root canals or periapical lesions was more sensitive than that of culture methods. 4. Seven samples revealed including P. endodontalis by PCR technique. Five of them were related with pains, two of them with sinus tract, three of them with foul odor, and three of them with purulent drainage. P. endodontalis was shown to have great relation with pains.

• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.653-660
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• 2004

Object-oriented analysis-synthesis coding (OOASC) subdivides each image of a sequence into a number of moving objects and estimates and compensates the motion of each object. It employs a motion parameter technique for estimating motion information of each object. The motion parameter technique employing gradient operators requires a high computational load. The main objective of this paper is to present efficient motion parameter estimation techniques using the hierarchical structure in object-oriented analysis-synthesis coding. In order to achieve this goal, this paper proposes two algorithms : hybrid motion parameter estimation method (HMPEM) and adaptive motion parameter estimation method (AMPEM) using the hierarchical structure. HMPEM uses the proposed hierarchical structure, in which six or eight motion parameters are estimated by a parameter verification process in a low-resolution image, whose size is equal to one fourth of that of an original image. AMPEM uses the same hierarchical structure with the motion detection criterion that measures the amount of motion based on the temporal co-occurrence matrices for adaptive estimation of the motion parameters. This method is fast and easily implemented using parallel processing techniques. Theoretical analysis and computer simulation show that the peak signal to noise ratio (PSNR) of the image reconstructed by the proposed method lies between those of images reconstructed by the conventional 6- and 8-parameter estimation methods with a greatly reduced computational load by a factor of about four.

• Korean Journal of Remote Sensing
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• v.30 no.4
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• pp.431-444
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• 2014

As applications of spaceborne SAR imagery are extended, there are increased demands for accurate registrations for better understanding and fusion of radar images. It becomes common to adopt multi-resolution SAR images to apply for wide area reconnaissance. Geometric correction of the SAR images can be performed by using satellite orbit and attitude information. However, the inherent errors of the SAR sensor's attitude and ground geographical data tend to cause geometric errors in the produced SAR image. These errors should be corrected when the SAR images are applied for multi-temporal analysis, change detection applications and image fusion with other sensor images. The undesirable ground registration errors can be corrected with respect to the true ground control points in order to produce complete SAR products. Speeded Up Robust Feature (SURF) technique is an efficient algorithm to extract ground control points from images but is considered to be inappropriate to apply to SAR images due to high speckle noises. In this paper, an attempt is made to apply SURF algorithm to SAR images for image registration and fusion. Matched points are extracted with respect to the varying parameters of Hessian and SURF matching thresholds, and the performance is analyzed by measuring the imaging matching accuracies. A number of performance measures concerning image registration are suggested to validate the use of SURF for spaceborne SAR images. Various simulations methodologies are suggested the validate the use of SURF for the geometric correction and image registrations and it is shown that a good choice of input parameters to the SURF algorithm should be made to apply for the spaceborne SAR images of moderate resolutions.

• Korean Journal of Remote Sensing
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• v.36 no.5_1
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• pp.835-846
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• 2020

Recent severe climate changes and extreme weather events have caused the uncommon types of forest ecosystem disturbances such as hails and gypsy moths. This paper describes the analysis of the forest ecosystem disturbances using ISODATA (Iterative Self-organizing Data Analysis Technique Algorithm) with the RapidEye and Sentinel-2 images, regarding the cases of the hail damages in Hwasun in 2017 and the gypsy moth damages in the Chiak Mountain in 2020. In the case of hail damages, the comparison of the June image of this study and the July field survey of the previous study showed that the damage severity increased from June to July as the drought overlapped after the trees were injured by the hails. In the case of gypsy moths, significant leaf damages were found from the image of June, and the damages were mainly distributed at the low-altitude slope near Wonju City. We made sure that satellite remote sensing is a very effective method to detect various and unusual forest ecosystem disturbances caused by climate change. Also, it is expected that the Korean Medium Satellite for Agriculture and Forestry scheduled to launch in 2024 can be actively utilized to monitor such forest ecosystem disturbances.

• The Korean Journal of Pharmacology
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• v.28 no.1
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• pp.1-9
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• 1992

Catecholamines, serotonin and their metabolites were measured in the posterior hypothalamus of urethane-anesthetized normotensive Wistar Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) using brain microdialysis which is a recently developed experimental method to measure the release of neurotransmitters and their metabolites at the localized brain area in vivo. Microdialysis probe was implanted stereotaxically to the rat posterior hypothalamus and perfused by Ringer's solution. Monoamines and their metabolites were quantified by reverse phase high performance liquid chromatography with electrochemical detection. In vitro recovery test of microdialysis showed that there exist inverse relationship between the perfusion flow rate and the relative recovery of neurochemical compounds. The estimated extracellular concentration of dopamine was about 32 nM, of norepinephrine 50 nM, of epinephrine 50 nM, of serotonin 73 nM, of 3, 4-dihydroxyphenylacetic acid (DOPAC) 281 nM, of homovanillic acid (HVA) 181 nM, and of 5-hydroxyindoleacetic acid (5HIAA) 3767 nM in the hypothalamic perfusate of the normotensive rat. There was no difference in the basal level of monoamines between the SHR and the WKY. In contrast, the level of DOPAC, HVA and 5HIAA in SHR was higher than that in the WKY, This study demonstrated that the microdialysis technique should be an applicable tool for in vivo measurement of central neurochemical substances.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.1-7
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• 2006

GOCi (Geostationary Ocean Color Imager) is one of the COMS payloads that KARI is currently developing and scheduled to be in operation from around 2008. Its primary objective is to monitor the Korean coastal water environmental condition. We report the current progress in development of the integrated optical model as one of the key analysis tools for the GOCI in-orbit performance verification. The model includes the Sun as the emitting light source. The curved Earth surface section of 2500 km x 2500 km includingthe Korean peninsular os defined as a Lambertian scattering surface consisted of land and sea surface. From its geostationary orbit, the GOCI optical system observes the reflected light from the surfaces with varying reflectance representing the changes in its environmental conditions. The optical ray tracing technique was used to demonstrate the GOCI in-orbit performances such as red tide detection. The computational concept, simulation results and its implications to the on-going development of GOCI are presented.