• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.9
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• pp.450-453
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• 2005

A high speed address recovery technique for AC plasma display panel(PDP) is proposed. Replacing GND switch by clamping diode. the recovery speed can be increased by saving GND hold-time and switching loss due to GND switch also becomes also be reduced. The proposed method is able to perform load-adaptive operation by controlling the voltage level of energy recovery capacitor, which prevents increasing inefficient power consumption caused by circuit loss during recovery operation. Test results with 50' HD single-scan PDP(resolution = 1366$\times$768) show that less than 3sons of recovery time is successfully accomplished and about$54\%$ of the maximum power consumption can be reduced, tracing minimum power consumption curves.

• Journal of the Korean Society of Radiology
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• v.5 no.2
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• pp.59-66
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• 2011

There is a difficulty because of classifying the anatomical structure in the neck CT scan by the beam hardening artifact no more than disease and it including the 6, 7 number cervical spine and intervertebral disk. In case of enforcing the neck CT scan cause of the inner diameter of beam artifact tried to be inquired by the image evaluation according to the change of the image evaluation according to the direction of the shoulder joint applying the variation method of a posture and location and Kernel value and it was most appropriate, the lion tax and Kernel value try to be searched for through an experiment. Somatom Sensation 16 (Siemens, Enlarge, Germany) equipment was used in a patient 30 people coming to the hospital for the neck CT scan. A workstation used the AW 4.4 version (GE, USA). According to a direction and location of the shoulder joint, the patient posture gave a change to the direction of the shoulder joint as the group S it gave a change as three postures and placed the both arms comfortably and helps a group N and augmented unipolar left in the wealthy merchant and group P it memorized the both hands and ordered the eversion and drops below to the utmost and enforced a scan. By using a reconstructing method as the second opinion, it gave and reconstructed the Kernel value a change based on scan data with B 10 (very smooth), B 20 (smooth), B 30 (medium smooth), B 40 (medium), B 50 (medium sharp), B 60 (sharp), and B 70 (very sharp). By using image data which gave the change of the examination posture and change of the Kernel value and are obtained, we analyzed through the noise value measurement and image evaluation of. The outside wire eversion orders the both hands and the examination posture is cost in the neck CT scan with the group P it drops below to the utmost. And in case of when reconstructing with B 40 (medium) or B 50 (medium sharp) being most analyzed into the inappropriate posture and Kernel value and applying the Kernel value to a clinical, it is considered to be very useful.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.157-160
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• 1996

In this paper, reconstruction algorithms of spiral scan imaging which has been used for ultra fast magnetic resonance imaging have been reviewed, and some simulation results using two different algorithms are reported. Since the trajectory of the spiral scan in k-space is the spiral, reconstruction of the spiral scan is not as straight forward as that used in Fourier imaging technique where the sampling points are usually on the rectangular grids. Originally the reconstruction of the spiral scan imaging was based on the convolution backprojection algorithm modified with a shift term, however, some other reconstruction techniques have also been tried by remapping sampling points from spiral trajectory to Cartesian grids. Some experimental aspects of MR spiral scan imaging will also be addressed.

• The Journal of Korean Society for Radiation Therapy
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• v.20 no.1
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• pp.17-23
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• 2008

Purpose: Cone-beam CT using linear accelerator attached to on-board imager is a image guided therapy equipment. Because it is to check the patient's set-up error, correction, organ and target movement. but imaging dose should be cause of the secondary cancer when taking a image. The aim of this study is investigation of appropriate cone beam CT scan mode to compare and estimate the image quality and skin dose. Materials and Methods: Measurement by Thermoluminescence dosimeter (TLD-100, Harshaw) with using the Rando phantom are placed on each eight sites in seperately H&N, thoracic, abdominal section. each 4 methods of scan modes of are measured the for skin dose in three time. Subsequently, obtained average value. Following image quality QA protocol of equipment manufacturers using the catphan 504 phantom, image quality of each scan mode is compared and analyzed. Results: The results of the measured skin dose are described in here. The skin dose of Head & Neck are measured mode A: 8.96 cGy, mode B: 4.59 cGy, mode C: 3.46 cGy mode D: 1.76 cGy and thoracic mode A: 9.42 cGy, mode B: 4.58 cGy, mode C: 3.65 cGy, mode D: 1.85 cGy, and abdominal mode A: 9.97 cGy, mode B: 5.12 cGy, mode C: 4.03 cGy, mode D: 2.21 cGy. Approximately, dose of mode B are reduced 50%, mode C are reduced 60%, mode D are reduced 80% a point of reference dose of mode A. the results of analyzed HU reproducibility, low contrast resolution, spatial resolution (high contrast resolution), HU uniformity in evaluation item of image quality are within the tolerance value by recommended equipment manufacturer in all scan mode. Conclusion: Maintaining the image quality as well as reducing the image dose are very important in cone beam CT. In the result of this study, we are considered when to take mode A when interested in soft tissue. And we are considered to take mode D when interested in bone scan and we are considered to take mode B, C when standard scan. Increasing secondary cancer risk due to cone beam CT scan should be reduced by low mAs technique.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.4
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• pp.322-328
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• 2000

In this paper, we were investigated the detectability on various specimen in self-designed test field using the GPR system with three antenna elements. The GPR system was constantly radiated 730MHz frequency. To examine the detectability on various condition, the test were experimented using different materials, size and buried depth. As an adjusted wave-propagation velocity, the location of hyperbolic curve pattern were displayed B-scan CRT. And the pattern was exactly positioned when it was compared to the real buried-depth. Therefore, we can confirm similarity between the wave-propagation velocity and previous results.

• Journal of Korean Neurosurgical Society
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• v.56 no.5
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• pp.400-404
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• 2014

Objective : Clip artifacts limit the visualization of intracranial structures in CT scans from patients after aneurysmal clipping with cobalt alloy clips. This study is to analyze the parameters influencing the degree of clip artifacts. Methods : Postoperative CT scans of 60 patients with straight cobalt alloy-clipped aneurysms were analyzed for the maximal diameter of white artifacts and the angle and number of streak artifacts in axial images, and the maximal diameter of artifacts in three-dimensional (3-D) volume-rendered images. The correlation coefficient (CC) was determined between each clip artifact type and the clip blade length and clip orientation to the CT scan (angle a, lateral clip inclination in axial images; angle b, clip gradient to scan plane in lateral scout images). Results : Angle b correlated negatively with white artifacts (r=-0.589, p<0.001) and positively with the angle (r=0.636, p<0.001) and number (r=0.505, p<0.001) of streak artifacts. Artifacts in 3-D images correlated with clip blade length (r=0.454, p=0.004). Multiple linear regression analysis revealed that angle b was the major parameter influencing white artifacts and the angle and number of streak artifacts in axial images (p<0.001), whereas clip blade length was a major factor in 3-D images (p=0.034). Conclusion : Use of a clip orientation perpendicular to the scan gantry angle decreased the amount of white artifacts and allowed better visualization of the clip site.

• Journal of the Korean Society of Radiology
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• v.13 no.7
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• pp.933-939
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• 2019

The purpose of this study is to provide basic clinical data by evaluating images, measuring absorbed dose and effective dose by using high resolution CT and low dose CT by using anthropomorphic chest phantom and glass dosimeter. Tissue dose was measured by inserting a glass dosimeter into the anthropomorphic chest phantom. A 64-slice CT system (SOMATOM Sensation 64, Siemens AG, Forchheim, Germany) and CARE Dose 4D were used, and the parameters of the high resolution CT were 120 kVp, Eff. Scan parameters of mAs 104, scan time 7.93 s, slice 1.0 mm (Acq. 64 × 0.6 mm), convolution kernel (B60f sharp) were used, and low dose CT was 120 kVp, Eff. mAs 15, scan time 7.41 s, slice 3.0 mm (Acq. 64 × 0.6 mm), scan of convolution kernel B50f medium sharp. CTDIvol was measured at 8.01 mGy for high resolution CT and 1.18 mGy for low dose CT. Low dose CT scans showed 85.49% less absorbed dose than high resolution CT scans.

• Journal of the Korea Convergence Society
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• v.8 no.5
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• pp.79-85
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• 2017

The purpose of this research was to evaluate the clinical and the instrument of convergence utility of transient elastography (FibroScan(R):electromagnetic wave) in diagnosing and treating liver ailments through a comparison and an analysis between liver function blood test and transient elastography (FibroScan(R)) in patients with chronic hepatitis B virus infection. Of all the patients with chronic hepatitis B virus infection who visited clinic B in Daejeon City between July 1, 2015, and February 28, 2016, 75 who underwent a FibroScan(R) test were selected for this study. Their laboratory and liver function test results were compared for a correlation analysis before constructing an ROC (Receiver Operation Characteristic) curve. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were 0.572 and 0.502, respectively, and showed highest correlation with fibrosis score, with statistical significance (p<0.000). Gamma glutamyltranspeptidase, total bilirubin, and alkaline phosphatase levels also showed relatively significant correlations in this order of sequence, while -fetoprotein and total protein levels did not show any statistically significant values. Albumin (-0.449) and platelet levels (-0.373) showed negative correlations with each other and no correlation with fibrosis score (p < 0.000). As liver fibrosis worsened, the accuracy of the ROC curve increased. At the F4 stage, which is the cirrhotic stage, the largest area under the curve was observed. FibroScan(R) showed significant correlation with the ALT (serum glutamic pyruvic transaminase) and AST (serum glutamic oxaloacetic transaminase) levels in the liver function test, which is a routine test for patients with chronic liver ailments. This implies that fibrosis correlates with liver inflammation severity.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.4
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• pp.333-336
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• 2008

A 52-year-old woman with a history of general weakness, fatigue, weight loss, elevated serum levels of liver transaminase enzyme for three months underwent an F-18 FDG PET/CT scan to evaluate a cause of the hepatosplenomegaly found on abdominal ultrasonography. Initial PET/CT revealed markedly enlarged liver and spleen with intense FDG uptake. Otherwise, there were no areas of abnormal FDG uptake in whole body image. Histological evaluation by a hepatic needle biopsy demonstrated diffuse large B cell type lymphoma and final diagnosis for this patient was hepatosplenic B-cell lymphoma. She received five cycles of CHOP chemotherapy, and second PET/CT scan was followed after then. Follow-up PET-CT revealed normal sized liver with disappearance of abnormal FDG uptake. Hepatosplenic B-cell lymphoma is relatively rare and mostly presents as single or multiple nodules.1,2 Diffuse type hepatosplenic lymphoma is extremely rare and poorly recognized entity.3 The diagnosis is very difficult and complicated by the presence of misleading symptoms.4 In this rare hepatosplenic B-cell lymphoma case, F-18 FDG PET/CT scan provided a initial diagnostic clue of hepatosplenic lymphoma and an accurate chemotherapy response.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.413-420
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• 2003

In this paper, the correction method of antenna beam direction errors is introduced which caused by frequency scan effect in active Phased may antenna for satellite communications. The antenna makes the beam directional error from frequency scan effect when it has dual beam may structure with asymmetrical series connection, their frequencies are different and for from each other, their 3dB beamwidth is narrow, and scan range is wide. By proposed equations, estimated beam direction error angles can be calculated and active phase shifter control values also can be calculated to compensate them. In this paper, the active phased array antenna system was fabricated to measure beam direction errors both before and after correction, which has dual beam from 32${\times}$4 main level array and 4${\times}$2 second level array, frequency deviation 500 MHz max.(6.7 %) at 7.25 GHz∼7.75 GHz ranges, 0$^{\circ}$∼${\pm}$35$^{\circ}$nm ranges, and 35.6 dBi gain with 2.2$^{\circ}$3 dB beam width. Its beam direction error by frequency san effect which was 2.5$^{\circ}$max., was reduced to 0.2$^{\circ}$max. after correction. This was 7 dB improvement of signal loss. The active phased array antenna can accurately track the target satellite for communications by this proposed correction method.