• Journal of radiological science and technology
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• v.30 no.2
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• pp.113-119
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• 2007

It is important to consider the contrast of object in Mammography because an absorption gap between tissues of body and breast in breast is low. This study is to evaluate MTF image with resolution chart according to change of combination of target and filter. The results were as follows : 1. There were significant differences in X-ray energy according to combination of filter(Mo/Mo, Mo/Rh. Mo/Al, Rh/Rh, Rh/Al) and acrylic thickness(2 cm, 3 cm, 4 cm). 2. The value of lp/mm on MTF to 0.5 showed that the sharpness in MTF curve was 2.4 compared to Mo/Mo and 2cm acryl, 2.63 in Mo/Rh and 4 cm acryl, and 2.9 in Rh/Rh and 6cm acryl. 3. The value of lp/mm on MTF showed that the resolution in MTF curve was 6.0 compared to Mo/Mo and 2 cm acryl, 4.60 in Rh/Al and 4cm acryl, and 6.03 in Rh/Al and 6 cm acryl. 4. The value of MTF on 2.5 lp/mm distinguishable visually was 0.48 compared to Mo/Mo and 2 cm acryl, 0.53 in Mo/Rh and 4cm acryl, and 0.59 in Rh/Rh and 6cm acryl. 5. For the evaluation of an image of the mammo-phantom, the score of Mo/Mo was 12 points, Mo/Rh 11, Rh/Rh 10.5, Mo/Al 10, Rh/Al 9.0, respectively.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.121-124
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• 2015

Digital Mammography is very important for the early diagnosis of breast cancer. but excessive radiation dose to the patient may increase the probability of occurrence of breast cancer. absorbed dose rate and signal, noise, and contrast in accordance with the change of the filter, and analyzed the signal-to-noise ratio. absorbed dose rate GE Equipment is higher than that of Siemens and Hologic. using the material of Mo / Mo was lower than the other target-filter combination. SNR of Siemens equipment is high and measured high when Mo / Mo selected, the other two devices was measured high when Mo / Rh selected. when you choose a target-filter combination our results will be a good indicator.

• Journal of the Korean Society of Tobacco Science
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• v.23 no.1
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• pp.60-64
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• 2001

The variability of a ventilated filter cigarette depends on the details of its construction and one properties of its components and the variations in filter ventilation is effected by many factors such as tobacco column pressure drop, filter pressure drop, tipping paper and plug wrap permeability, and vent position. In this study, the effects of combination of tipping paper and plug wrap on filter ventilation of cigarettes were studied for the target ventilation level under the specific tobacco column and filter tip in order to reduce the variation of filter ventilation. When Nicolas Baskevitch\`s equation on filter ventilation was used to try out Monte Carlo Simulation, at the combination where tipping paper permeability is high and plug wrap permeability is low, even the small change in tipping paper and plug wrap permeability showed high variation of target ventilation level. Also, according to the analysis data of filter ventilation in cigarettes designed at the level of 45% filter ventilation by the combinations with tipping paper and plug wrap, the variation in cigarette filter ventilation was increased as increasing tipping paper permeability and decreasing plug wrap permeability. As the results of this study, the variation of filter ventilation can be reduced by increasing plug wrap permeability/tipping paper permeability ratio in the cigarette design, considering 2-3% of tipping paper permeability variation(%CV) and about 10% of plugwrap permeability variation.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.103-109
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• 2016

The performance of a multi-head, computerized combination scaling system to automatically identify a group of agricultural products having a total weight within the target range has been optimized to reduce the package cycle time of the merchandise. First, the structure of the scale was modified to enable faster measurement by enhancing the dynamic stability during the process. Second, the high frequency noise in the measured signal was eliminated by a high frequency filter to provide more accurate weight data. Finally, the algorithm to identify a group of products with a total weight within the target range was modified to enable a user to select an optimal number of scales. According to the experimental verifications, this modified system reduced the package cycle time significantly and also was accurate in measuring the total weight of the selected products.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.168-172
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• 2012

This paper is focusing on the comparison of different kinds of BPFs(Band Pass Filters) passing signals with a particular frequency band. According to the different classifications, features and target application systems, BPF has many types. Chebyshev filter which has a steep slope and a few ripples, and Butterworth filter which has no ripple but gentle slope are the most typical BPFs. The ideal filter is flat in the passband and the slope in the transition band is perpendicular. In this paper, we suggest the cascading Chebyshev BPF with the advantages of the Chebyshev filter and the Butterworth filter simultaneously to make a closest filter to an ideal filter. The proposing BPF is the tenth Chebyshev BPF cascading the fourth and the sixth, and it is designed as the tenth cascading Chebyshev BPF. To measure the performance of the designing filter, we have compared and analyzed the tenth Chebyshev filter with the tenth Butterworth filter. As a result, the tenth cascading Chebyshev BPF has decreased the ripple more than 1/4 [dB] in the passband. Finally, the output of the simulation showed the validity of the proposing cascading Chebyshev filter.

• The Journal of the Korea Contents Association
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• v.14 no.6
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• pp.247-254
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• 2014

For the purpose of early diagnosis of the breast cancer, the attention on the screening mammography has been increasing-with supply of digital mammography day by day. Image quality is decided by target materials and filter combinations. Optimized selection by a glandular density and a thickness is needed, because these combinations change x-ray spectrum and effect to image quality. The purpose of this study is to find out optimized target and filter combinations through the evaluation of quantitative image quality and to suggest means which minimize patient dose through MCNPX. In results, spatial frequency resolution evaluation which is quantitative image quality evaluation method, MTF, NPS, DQE shows that we have to select Mo/Mo combinations or Mo/Rh combinations when compressed breast is thin. but in case of that when compressed breast is thick, we have to select Rh/Rh combinations or W /Rh combinations. In a comprehensive evaluation, W!Rh combinations which are not used in thin breasts in practice was superior to all image quality evaluation. This result is somewhat different-with clinical examination results. Secondary end point was organ dose evaluation, radiation dose of opposite breast was approximately 47 ~73% effectiveness when selecting standard breast. In conculsion, the most important point is that we have to select the optimal combinations-with considering dose evaluation and various thickness.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.307-312
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• 2015

ARPA(Automatic Radar Plotting Aid) is a device to calculate CPA(closest point of approach)/TCPA(time of CPA), true course and speed of targets by vector operation of relative courses and speeds. The purpose of this study is to develop target acquisition and tracking technology for ARPA Radar implementation. After examining the previous studies, applicable algorithms and technologies were developed to be combined and basic ARPA functions were developed as a result. As for main research contents, the sequential image processing technology such as combination of grayscale conversion, gaussian smoothing, binary image conversion and labeling was deviced to achieve a proper target acquisition, and the NNS(Nearest Neighbor Search) algorithm was appllied to identify which target came from the previous image and finally Kalman Filter was used to calculate true course and speed of targets as an analysis of target behavior. Also all technologies stated above were implemented as a SW program and installed onboard, and verified the basic ARPA functions to be operable in practical use through onboard test.

• Journal of radiological science and technology
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• v.30 no.1
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• pp.13-23
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• 2007

In recent years, mammography system is changed rapidly from conventional screen-film system to digital system for application to screening and diagnosis. Digital mammography system provides several advantages over screen-film mammography system. According to the information provided by the manufacturer, digital mammography system offers radiation dose reduction in comparison with screen-film mammography system, because of digital detector, particularly direct digital detector has higher x-ray absorption efficiency than screen-film combination or imaging plate(IP). We measured average glandular doses(AGD) in screen-film mammography(SFM) system with slow screen-film combination, computed mammography(CM) system, indirect digital mammography(IDM) system and direct digital mammography(DDM) system using brest tissue-equivalent phantom(glandularity 30%, 50% and 70%). The results were shown as follows : AGD values for DDM system were highest than those for other systems. Although automatic exposure control(AEC) mode was selected, the curve of the AGD values against thickness or glandularity increased significantly for the SFM system with the uniform target/filter(Mo/Mo) combination. Therefore, the AGD values for the high energy examinations were highest in the SFM system, and those for the low energy examinations were highest in the DDM system. But the curve of the AGD values against thickness and glandularity increased gently for CM system with the automatic selection of the target/filter combination (from Mo/Mo to Mo/Rh or from Mo/Rh to Rh/Rh), and the AGD values were lowest. Consequently, the parameters in mammography for each exposure besides detection efficiency play an important role in oder to estimate a patient radiation dose.

• The Journal of Korean Society for Radiation Therapy
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• v.34
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• pp.7-12
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• 2022

Purpose: When it is difficult to secure the skin dose when treating Irregularly Shaped Skin Surface such as the nose where it is difficult to apply a bolus, increase the skin dose with a treatment plan that combines the IMRT (Intensity Modulated Radiation Therapy) delivery technique and FFF (Flattening Filter Free), It was tried to find out whether or not through the phantom experiment. Materials & Methods: Based on the 6MV-FF (Flattening Filter) and VMAT (Volumetric-Modulated Arc Therapy) treatment plans, which are the most commonly used treatment plans for head and neck cancer, A comparison group was created by combining VMAT and IMRT, FF and FFF, and the presence or absence of 5 mm bolus application. A virtual target was created on the Rando Phantom's nose, and a virtual bolus of 5 mm was applied assuming full contact on the Rando Phantom's nose. Five measurement points were determined based on the phantom's nose, and the absorbed dose was measured by irradiating each treatment plan 3 times per treatment plan according to the treatment technique and whether or not the bolus was applied. Result: The difference in skin dose in FF vs FFF increased in the case of FFF in VMAT bolus off, and there was no difference in case of IMRT bolus off. In VMAT bolus 5 mm and IMRT bolus 5 mm, it was confirmed that the skin dose was rather decreased in FFF. The difference in skin dose between VMAT and IMRT increased only in the case of FFF bolus off, and there was no statistical difference in the rest. For the difference in skin dose between bolus off vs bolus 5 mm, it was confirmed that the skin dose increased at bolus 5 mm, except for the case of using IMRT FFF. The treatment plan combining IMRT and FFF did not find any statistically significant difference as a result of analyzing the measured values of the treatment plan skin dose applied with a 5 mm bolus using the commonly used VMAT and FF. Therefore, it is thought that by using IMRT_FFF, it is possible to deliver a skin dose similar to that of applying a 5 mm bolus to VMAT_FF, which can be useful for patients who need a high skin dose but have difficulty applying a bolus. Conclusion: For patients who find it difficult to apply bolus, an increase in skin dose can be expected with a treatment plan that properly combines IMRT and FFF compared to VMAT and FF.

• Journal of radiological science and technology
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• v.29 no.4
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• pp.267-274
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• 2006

The evaluation of GB stones with ultrasound has proved to be useful procedure in patient with symptoms of cholelithiasis. GB is evaluated for size, wall thickness, presence of internal reflections within the lumen and posterior acoustic shadowing or enhancement in Ultrsonography. The patient position should be shifted during procedure to demonstrate further the presence of stone within the GB. Patient scanned at the Rt. subcostal region in supine, right lateral, Lt. down decubitus, and upright sitting position. So GB stone should shift to dependent area of GB. Often, GB is not markedly distended in the presence of cholethiasis, and so the diagnosis becomes more difficult. One of the more difficult areas for detection of a GB stones are embeded in the cystic duct region. And since the GB is adjacent to the duodenum and hepatic flexure, its may be difficult to visualizing a GB stone. When patient study position changes frome supine to other position, stones displaced the site. But if its are polyps, not changes the site whatever patient positions. It is very important to what make different GB stones or polyps. We have studied about mobility of GB stones according to the patients position(supine, Lt. down decubitus, $30^{\circ} LAO. sitting and hand-knee). So we have a result, stones wherever localized within the GB, changed 100% its position in the hand-knee position and the others appeared at least 90%. In this study, when a large stones are located through fundus-body and body-neck, does not changing the stones position in spite of varied patient's positions. But hand-knee positions can identified GB stones, because its make changed the position of stons from posterior wall to anterior wall within the GB. We recommend the hand-knee position for differentiation GB stones from polyps.