• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.21-26
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• 2024

The one of the famous deep learning models for object detection task is you only look once version 5 (YOLOv5) framework based on the one stage architecture. In addition, YOLOv5 model indicated high performance for accurate lesion detection using the bottleneck CSP layer and skip connection function. The purpose of this study was to evaluate the performance of YOLOv5 framework according to various hyperparameters in position emission tomogrpahy (PET) phantom images. The dataset was obtained from QIN PET segmentation challenge in 500 slices. We set the bounding box to generate ground truth dataset using labelImg software. The hyperparameters for network train were applied by changing optimization function (SDG, Adam, and AdamW), activation function (SiLU, LeakyRelu, Mish, and Hardwish), and YOLOv5 model size (nano, small, large, and xlarge). The intersection over union (IOU) method was used for performance evaluation. As a results, the condition of outstanding performance is to apply AdamW, Hardwish, and nano size for optimization function, activation function and model version, respectively. In conclusion, we confirmed the usefulness of YOLOv5 network for object detection performance in nuclear medicine images.

• Proceedings of the Korea Contents Association Conference
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• 2017.05a
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• pp.107-108
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• 2017

3차원 위상대조도 기법의 단점인 긴 검사시간으로 인해 임상적 유용성이 떨어진다. 본 논문은 시간매개변수인 병렬영상기법(Grappa) 변경에 따른 혈류정보의 정량적 평가를 통해 차이점을 알아보고 임상적 활용정도를 평가하였다. 자체 제작한 혈류팬텀을 통해 실험하였으며, Grappa을 5번 변경하여 실험하였다. 연구결과, Grappa를 적용하지 않았을 경우 혈류속도는 평균 9.42로 총 4단계를 적용한 혈류속도 차이율은 각각(1.4, 1.5, 0.4, 1.5%)이었으며 flow와 WSS도 각각(1.4, 1.6, 0.8, 25%), (2.1, 1.4, 1.1, 0.8%)이었다. 통계적으로도 유의하지 않아 Grappa를 적용하지 않은 검사법과 혈류정보가 동일하였다.(P>0.05) 긴 검사 시간으로 인해 임상적 활용이 떨어지는 짧은 검사시간을 요하는 소아환자나 중등도 환자 또는 폐쇄공포증 환자에게 시간을 단축한 3차원 위상대조도 기법을 사용하여 단점을 보완한다면 임상적 활용가치가 높아질 것이라 사료된다.

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.2
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• pp.65-74
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• 2019

Purpose: Recently, A Catcher was added to prevent sagging in Radixact^® X9. In this study, We quantitatively compared general couch of Tomo-HDA^® with catcher couch of Radixact^® X9 using the human phantom and evaluated usefulness of catcher. Materials and methods: We used rando phantom for phantom study and set the each iso-center of head and neck region and Pelvis region for region parameter. Furthermore, We used hand made low melting point alloys for weight parameter. MVCT(Mega Voltage Computed Tomography) images were acquired for vertical error and rotation(pitch) error measurement increasing weight(A: 15kg, A+B: 30kg, A+B+C: 45kg). We selected 120 patients who has been treated using Tomotherpy machine for patient study. 60 patients has been treated in Tomo-HDA^® and the other 60 patients treated in Radixact^® X9. In the patient study methods, vertical error and rotation(pitch) error was measured for mean value calculation using MVCT images acquired on first day of radiation therapy. Result: Result of phantom study, Vertical error and rotation(pitch) error was increased proportionally increased as the weight increases in general couch of Tomo-HDA^®. each maximum value was 7.52mm, 0.38° in head and neck region and 11.94mm, 0.92° in pelvis region. However, We could confirm that there was stable error range(0.02~0.1mm, 0~0.04°) in Catcher couch of Radixact^®. Result of patient study, The head and neck region was measured 4.79mm 0.33° lower, and the pelvis region was measured 7.66mm, 0.22° lower in Catcher couch of Radixact^® X9. Conclusion: In this study, Vertical error and rotation(pitch) error was proportionally increased as the weight increases in general couch of Tomo-HDA^®. Especially, The pelvis region error was more increased than the head and neck region error. However, Vertical error and rotation(pitch) error was regularly generated regardless of weight or regions in Catcher^TM couch of Radixact^® X9 that this study's purpose. In conclusion, Catcher^TM couch of Radixact^® X9 can minimize mechanical error that couch sagging. Furthermore, The pelvis region is more efficiency than head and neck region. In radiation therapy using Tomotherapy machine, it is regarded that may contribute to minimizing unadjusted pitch error due to characters of Tomotherapy.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.17-24
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• 2011

Purpose: Presently in the nuclear medicine field, the high-speed image reconstruction algorithm like the OSEM algorithm is widely used as the alternative of the filtered back projection method due to the rapid development and application of the digital computer. There is no to relate and if it applies the optimal parameter be clearly determined. In this research, the quality change of the Jaszczak phantom experiment and brain SPECT patient data according to the iteration times and subset number change try to be been put through and analyzed in 3D OSEM reconstruction method of applying 3D beam modeling. Materials and Methods: Patient data from August, 2010 studied and analyzed against 5 patients implementing the brain SPECT until september, 2010 in the nuclear medicine department of ASAN medical center. The phantom image used the mixed Jaszczak phantom equally and obtained the water and 99mTc (500 MBq) in the dual head gamma camera Symbia T2 of Siemens. When reconstructing each image altogether with patient data and phantom data, we changed iteration number as 1, 4, 8, 12, 24 and 30 times and subset number as 2, 4, 8, 16 and 32 times. We reconstructed in reconstructed each image, the variation coefficient for guessing about noise of images and image contrast, FWHM were produced and compared. Results: In patients and phantom experiment data, a contrast and spatial resolution of an image showed the tendency to increase linearly altogether according to the increment of the iteration times and subset number but the variation coefficient did not show the tendency to be improved according to the increase of two parameters. In the comparison according to the scan time, the image contrast and FWHM showed altogether the result of being linearly improved according to the iteration times and subset number increase in projection per 10, 20 and 30 second image but the variation coefficient did not show the tendency to be improved. Conclusion: The linear relationship of the image contrast improved in 3D OSEM reconstruction method image of applying 3D beam modeling through this experiment like the existing 1D and 2D OSEM reconfiguration method according to the iteration times and subset number increase could be confirmed. However, this is simple phantom experiment and the result of obtaining by the some patients limited range and the various variables can be existed. So for generalizing this based on this results of this experiment, there is the excessiveness and the evaluation about 3D OSEM reconfiguration method should be additionally made through experiments after this.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.355-362
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• 2010

This study determines a range of CT parameter values in Brain CT which are minimizing patient absorption dose without compromising the image quality and optimal exposure condition. We measured dose and image noise using conventional CT parameters in Brain CT. In additon, we evaluated dose, SNR and PSNR of head phantom images while changing kVp and rotation time. In this study, effectiveness of dose that was achieved from dose reproducible experiments in conventional head CT condition is determined by changing kVp and rotation time. Dose and PSNR is related to low dose-high resolution condition. In conclusion, we suggest that using proposed conditions is effective for imaging to compare with conditions proposed by the manufacturer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.192-203
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• 2016

The purpose of this study is to investigate the effects of task conflict on job attitudes (organizational commitment & job satisfaction), focusing on the mediating effects of supervisory communication & co-worker communication. Recently, the importance of communication as a research topic has been increasing. According to prior research, communication satisfaction has a positive effect on job performance. However, studies which take into account the different types of communication are lacking. Therefore, this study considered two types of communication (supervisory communication and coworker communication). A research model and hypotheses were developed in order to examine the theoretical research issues and questions. The sample consisted of 280 survey data drawn from employees in firms located in Korea. The data was analyzed by the statistical packages, SPSS 21.0 & AMOS 21.0 for Windows. The findings of the analysis are as follows. Firstly, it was found that task conflict had a negative (-) effect on organizational commitment & job satisfaction. Therefore, H1a & H1b are supported. Secondly, it was found that task conflict had a negative (-) effect on supervisory communication. Therefore, H2a is supported. However, it did not have a significant effect on co-worker communication. Hence, H2b is not supported. Thirdly, as regards the mediating effect of supervisory communication, it was found that supervisory communication mediated the effect of task conflict on job attitudes (organizational commitment & job satisfaction). Therefore, H3a & H3b are supported. Finally, the mediating effect of co-worker communication was not significant. Therefore, none of the sub-hypotheses of H4 are supported. Based on these findings, this study suggested directions for future research.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.229-238
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• 2018

The purpose of this study is to examine the difference in the mediating effects of relief from fatigue through sleep and perceived subjective health in the relationship between perceived stress and subjective happiness in middle school students who attempted suicide. The analysis was conducted using Path analysis, the Bootstrapping method, Phantom variable and Multiple group analysis by AMOSS using the IBM SPSS 23 and IBM SPSS AMOS 23 programs with 820 middle school students who attempted suicide in the past 12 months using the raw data of the Korea Risk Behavior Web-Based Survey (2016). In the relationship between perceived stress and perceived subjective health, the indirect effect of relief from fatigue through sleep and perceived subjective health (${\beta}=-.12$, p=.003) was statistically significant. The difference in the magnitude of the two indirect effects was found to be greater for the subjective health status than for relief from fatigue through sleep (difference = .02, p=.028) and the effects were greater for the males (${\beta}=.44$, p <.001) than for the females (${\beta}=.23$, p<.001). Based on the findings, it is necessary to develop and apply an educational program that includes the factors that contribute to improving the happiness of middle school students.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.1-9
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• 2023

For optimal image quality of computer tomography angiography (CTA), different iodine concentrations and scan parameters were applied to quantitatively evaluate the image quality characteristics of filtered back projection (FBP), hybrid-iterative reconstruction (hybrid-IR), and deep learning reconstruction (DLR). A 320-row-detector CT scanner scanned a phantom with various iodine concentrations (1.2, 2.9, 4.9, 6.9, 10.4, 14.3, 18.4, and 25.9 mg/mL) located at the edge of a cylindrical water phantom with a diameter of 19 cm. Data obtained using each reconstruction technique was analyzed through noise, coefficient of variation (COV), and root mean square error (RMSE). As the iodine concentration increased, the CT number value increased, but the noise change did not show any special characteristics. COV decreased with increasing iodine concentration for FBP, adaptive iterative dose reduction (AIDR) 3D, and advanced intelligent clear-IQ engine (AiCE) at various tube voltages and tube currents. In addition, when the iodine concentration was low, there was a slight difference in COV between the reconstitution techniques, but there was little difference as the iodine concentration increased. AiCE showed the characteristic that RMSE decreased as the iodine concentration increased but rather increased after a specific concentration (4.9 mg/mL). Therefore, the user will have to consider the characteristics of scan parameters such as tube current and tube voltage as well as iodine concentration according to the reconstruction technique for optimal CTA image acquisition.

• The Journal of the Acoustical Society of Korea
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• v.27 no.2
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• pp.57-65
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• 2008

Setting parameters of Ultrasonic scanners influence the quality of ultrasonic images. In order to obtain optimized images sonographers need to understand the effects of the setting parameters on ultrasonic images. The present study considered typical four parameters including TGC (Time Gain Control), Gain, Frequency, DR (Dynamic Range). LCS (low contrast sensitivity) was chosen to quantitatively compare the quality of the images. In the present experiment LCS targets of a standard ultrasonic test phantom (539, ATS, USA) were imaged using a clinical ultrasonic scanner (SA-9000 PRIME, Medison, Korea). Altering the settings in the parameters of the ultrasonic scanner, 6 LCS target images (+15 dB, +6 dB, +3 dB, -3 dB, -6 dB, -15 dB) to each setting were obtained, and their LCS values were calculated. The results show that the mean pixel value (LCS) is the highest at the max setting in TGC, mid to max in gain and pen mode in frequency and 40-66 dB in DR. Among all images, the image being the highest in LCS was obtained at the setting of DR 40 dB. It is expected that the results will be of use in setting the parameters when ultrasonically examining masses often clinically found In either solid lesions (similar to +15, +6, +3 dB targets) or cystic lesions (similar to -15, -6, -3 dB targets).

• Progress in Medical Physics
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• v.14 no.2
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• pp.131-140
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• 2003

As the importance of accuracy in measurings of 3-D anatomical structures continues to be stressed, an objective and quantitative of assessing image quality and accuracy of 3-D volume-rendered images is required. The purpose of this study was to evaluate the quantitative accuracy of 3-D rendered images obtained with MDCT, scanned at various scanning parameters (scan modes, slice thicknesses and reconstruction slice thickness). Twelve clinically significant points that play an important role for the craniofacial bone in plastic surgery and dentistry were marked on the surface of a dry human skull. The direct distances between the reference points were defined as gold standards to assess the measuring errors of 3-D images. Then, we scanned the specimen with acquisition parameters of 300 mA, In kVp, and 1.0 sec scan time in axial and helical scan modes (pitch 3:1 and 6:1) at 1,25 mm, 2.50 mm, 3.75 mm and 5.00 mm slice thicknesses. We performed 3-D visualizations and distance measurements with volumetric analysis software and statistically evaluated the quantitative accuracy of distance measurements. The accuracy of distance measurements on the 3-D images acquired with 1.25, 2.50, 3,75 and 5.00 mm slice thickness were 48%, 33%, 23%, 14%, respectively, and those of the reconstructed 1.25 mm were 53%, 41%, 43%, 36% respectively. Meanwhile, there were insignificant statistical differences (P-value<0.05) in the accuracy of the distance measurements of 3-D images reconstructed with 1.25 mm thickness. In conclusion, slice thickness, rather than scan mode, influenced the quantitative accuracy of distance measurements in 3-D rendered images with MDCT. The quantitative analysis of distance measurements may be a useful tool for evaluating the accuracy of 3-D rendered images used in diagnosis, surgical planning, and radiotherapeutic treatment.