• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.31-42
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• 2009

Purpose: As the number of domestic medical institutions installing PET/CT is increasing rapidly, the transfer of PET/CT images among medical institutions is also increasing. Thus, it is necessary to collect the comparative SUV data from several medical institutions' PET/CT systems through a phantom study which semi-quantitatively compares the SUV on one bed, the change scale of the SUV on the slices, and the time of measuring. The phantom study to find differences among the SUVs from various PET/CT offers the opportunity to obtain the reliability of the SUV in PET/CT images. Materials and Methods: Ten PET/CT systems from medical institutions in Korea were used. To obtain the accurate data, the study has been using the radiation detector of Korea Research Institute of Standards and Science to verify. The internal structures of NEMA $phantom^{TM}$ were removed and Six thousand milliliters of distilled water which has 1mCi of $^{18}F$-FDG put into the phantom. The water was properly integrated with $^{18}F$-FDG using magnetic stirrer. The images were acquired at 60, 70, 80, 90, 100, 110 and 120-minutes for 3 minute each. Two hundred square centimeters of region of interests were placed and analyzed. To confirm the usefulness, the correction-table came out from patients' data. Results: The coefficient of variability of the SUV from -11.0 to 9.90 % fell into the range of international standards(${\pm}10%$) along with the SUV on a bed, the change scale of the SUV on the slices, and the time of measuring, except one PET/CT system. Using the data of the differences among the SUVs, we came to withdraw the correction-table ranging from 0.803 to 1.246. The correction-table was confirmed its usefulness through Linear Regression Analysis which was applied to normal cases. Conclusions: Although studies have been made on the variation of the SUV, there is little attention on the standardization of the SUV. Based on this study of the quantitatively comparable data about the SUV accommodating the correction-table, it would help to have more corrective diagnosis.

• Journal of Biomedical Engineering Research
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• v.25 no.5
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• pp.329-334
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• 2004

The electronic nose (E-nose) recently finds its applications in medical diagnosis, specifically on detection of diabetes, pulmonary or gastrointestinal problem, or infections by examining odors in the breath or tissues with its odor characterizing ability. The odor recognition performance of E-nose can be improved by manipulating the sensor array responses of vapors in time-profile forms. The different chemical interactions between the sensor materials and the volatile organic compounds (VOC's) leave unique marks in the signal profiles giving more information than collection of the conventional piecemal features, i.e., maximum sensitivity, signal slopes, rising time. In this study, to use them in vapor recognition task conveniently, a novel time-profile method was proposed, which is adopted from digital image pattern matching. The degrees of matching between 8 different vapors were evaluated by using the proposed method. The test vapors are measured by the silicon-based gas sensor array with 16 CB-polymer composites installed in membrane structure. The results by the proposed method showed clear discrimination of vapor species than by the conventional method.

• Journal of Biomedical Engineering Research
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• v.24 no.2
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• pp.77-82
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• 2003

Virtual colonoscopy is a non-invasive computerized procedure to detect polyps by examining the colon from a CT data set. To fly through the inside of colons. the extraction of a suitable flight-path is necessary to Provide the viewpoint and view direction of a virtual camera. However. manual path extraction by Picking Points is a very time-consuming and difficult task due 1,c, the long and complex shape of colon. Also, existing automatic methods are computationally complex. and tend to generate an improper and/or discontinuous path for complicated regions. In this paper, we propose a fast flight-path generation algorithm using the distance and order maps. The order map Provides all Possible directions of a path. The distance map assigns the Euclidean distance value from each inside voxel to the nearest background voxel. By jointly using these two maps. we can obtain a proper centerline regardless of thickness and curvature of an object. Also, we Propose a simple smoothing technique that guarantees not to collide with the surface of an object. The phantom and real colon data are used for experiments. Experimental results show that for a set of human colon data, the proposed algorithm can provide a smoothened and connected flight-path within a minute on an 800MHz PC. And it is proved that the obtained flight-Path provides successive volume-rendered images satisfactory for virtual navigation.

• Progress in Medical Physics
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• v.20 no.3
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• pp.159-166
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• 2009

Obviously, the administration of the prescribed amount of activity to the patient requires proper operation of the dose calibrator, which shall be verified by implementing the required quality control on the instrument. This investigation examined the accuracy and precision of dose calibrator activity measurement of the radiopharmaceutical F-18 FDG. To investigate the status of the nuclear medicine centers in Korea for the performance of dose calibrators, 10 centers providing PET/CT system services in Korea were inspected in 2008. We measured accuracy and precision in 10 equipments in consideration of PET/CT model, installation area, and installation time. According to the results of comparative analysis of 10 dose calibrators used to measure radioactivity of F-18 FDG, accuracy was -5.00~4.50% and precision was 0.05~0.45%, satisfying the international standards, which are accuracy ${\pm}$10% and precision ${\pm}$5%. This study demonstrated that, for accurate measurements, no adjustment is necessary for a dose calibrator setting when measuring different dose calibrators of F-18 FDG activity prescriptions.

• Journal of Cadastre & Land InformatiX
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• v.52 no.1
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• pp.17-36
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• 2022

The purpose of this study is to diagnose problems in the regulation and management of Restricted Development Zone and to prepare a construction plan to convert it to a data-based monitoring system. Unlike other land-use zones, the Restricted Development Zone is a exceptional zone that prohibits all development activities other than the minimum maintenance and must be strictly controlled and managed by the local government. However, the current Restricted Development Zone management is distributed according to the conditions of each local government, and it is not possible to monitor changes in the entire Restricted Development Zone as shown in the survey results. In particular, in this study, by introducing an AI-based monitoring system, MOLIT sends the results of detecting changes across the country at regular time points(monthly and quarterly) to the local governments based on the same regulation standards, and the local governments can be trusted while inputting the regulation results into the system. To propose this methodology, first, a survey and interview were conducted with local government officials and experts. Second, we analyzed cases in which AI analysis was applied to local governments and proposed a plan to improve the efficiency of regulation work according to the introduction of the monitoring system. Third, a plan was prepared to establish a monitoring system based on the advancement of the management information system. This monitoring system can be expanded and applied to land that needs periodic regulation and management in the future, and this study tried to propose a methodology and policy for this.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.217-225
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• 2019

The purpose of this study was to quantitate signal to noise ratio and contrast to noise ratio of the portal vein using CT and 3.0T MRI and to investigate the optimal imaging device. Twenty patients who inspective CT and 3.0T MRI between February 2018 and April 2018 were randomly assigned to receive data from the picture archiving communication system. The SNR and CNR values were evaluated by measuring the mean and standard deviation of the region of interest of the four regions of the portal vein (the main portal vein, the right vein, the left vein, and the middle vein). The results showed that SNR was 9.180.72 in the right context, 9.410.84 in the left context, 9.540.59 in the middle context, 9.550.75 in the order context, and 22.292.03 in the right context and 25.893 in the 3.0T MRI. 19, median context: 24.392.87, and order Mac: 26.642.30 (p<0.05). CNR was 3.790.68 in the CT context, 3.740.65 in the left context, 3.710.39 in the middle context, 3.790.68 in the order context, 9.490.65 in the right context, and 11.0001.90 in the 3.0T MRI, Intermediate context: 12.701.75, order Mac: 10.010.98, 3.0T MRI was higher than CT (p<0.05). In conclusion, SNR and CNR values were higher in the 3.0T MRI than CT in the 4 portal regions. Therefore, 3.0T MRI using non-ionizing radiation was the most superior imaging equipment than CT.

• The KIPS Transactions:PartB
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• v.19B no.2
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• pp.123-126
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• 2012

This paper proposed a method to separate a liver into left and right liver lobes for simple and exact volumetry of the river graft at abdominal MDCT(Multi-Detector Computed Tomography) image before the living donor liver transplantation. A medical team can evaluate an accurate river graft with minimized interaction between the team and a system using this algorithm for ensuring donor's and recipient's safe. On the image of segmented liver, 2 points(PMHV: a point in Middle Hepatic Vein and PPV: a point at the beginning of right branch of Portal Vein) are selected to separate a liver into left and right liver lobes. Middle hepatic vein is automatically segmented using PMHV, and the cutting line is decided on the basis of segmented Middle Hepatic Vein. A liver is separated on connecting the cutting line and PPV. The volume and ratio of the river graft are estimated. The volume estimated using 2 points are compared with a manual volume that diagnostic radiologist processed and estimated and the weight measured during surgery to support proof of exact volume. The mean ${\pm}$ standard deviation of the differences between the actual weights and the estimated volumes was $162.38cm^3{\pm}124.39$ in the case of manual segmentation and $107.69cm^3{\pm}97.24$ in the case of 2 points method. The correlation coefficient between the actual weight and the manually estimated volume is 0.79, and the correlation coefficient between the actual weight and the volume estimated using 2 points is 0.87. After selection the 2 points, the time involved in separation a liver into left and right river lobe and volumetry of them is measured for confirmation that the algorithm can be used on real time during surgery. The mean ${\pm}$ standard deviation of the process time is $57.28sec{\pm}32.81$ per 1 data set ($149.17pages{\pm}55.92$).

• Korean Journal of Optics and Photonics
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• v.31 no.1
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• pp.1-6
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• 2020

The chest wall, an organ directly affected by environmental particles through respiration, consists of ribs, a pleural layer and intercostal muscles. To diagnose early and treat disease in this body part, it is important to visualize the details of the chest wall, but the structure of the pleural layer cannot be seen by chest computed tomography or ultrasound. On the other hand, optical coherence tomography (OCT), with a high spatial resolution, is suited to observe pleural-layer response to talc, one of the fine materials. However, intensity-based OCT is weak in providing information to distinguish the detailed structure of the chest wall, and cannot distinguish the reaction of the pleural layer from the change in the muscle by the talc. Polarization-sensitive OCT (PS-OCT) takes advantage of the fact that specific tissues like muscle, which have optical birefringence, change the backscattered light's polarization state. Moreover, the birefringence of muscle associated with the arrangement of myofilaments indicates the muscle's condition, by measuring retardation change. The PS-OCT image is interpreted from three major perspectives for talc-exposure chest-wall imaging: a thickened pleural layer, a separation between pleural layer and muscle, and a phase-retardation measurement around lesions. In this paper, a rabbit chest wall after talc pleurodesis is investigated by PS-OCT. The PS-OCT images visualize the pleural layer and muscle, respectively, and this system shows different birefringence of normal and damaged lesions. Also, an analyisis based on phase-retardation slope supports results from the PS-OCT image and histology.

• Korean Business Review
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• v.17 no.2
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• pp.63-87
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• 2004

To create and maintain comparative supremacy as a strategic tool of business, many organizations have introduced informational technology and system. By using this system, Some companies got a beneficial value for achieving organizational goals but others could not obtain their effectiveness and efficiency. In particular, a lot of organizations that tried to make strategic supremacy with e-commercial trade are under hard condition because of poor profit. It implies that it is essential to identify and analyse the consumer who uses e-commercial trade. This paper, therefore, focusing on internet shopping malls between business and consumer as one of areas of e-commercial trades, shows the difference between consumer expectation and performance. The results of this study are as follows: First, as for the significant difference of influencing factors to consumer satisfactions according to the types of internet shopping malls, there is a meaningful difference in consumer anxiety and internet usefulness, but not in consumer service. Prior to verify the differences in detail on consumer's anxiety and internet usefulness, we examined that there is any difference between expectation and performance. T-test was used for the variants of consumer anxiety and internet usefulness, and its meaningful probability was 0.000, which means that both showed statistically significant difference. Based on the results, we also found that regardless of the types of internet shopping malls, consumer expectation was greater than performance. although the difference between expectation and performance was not equal according to the internet shopping malls. Second, a regression analysis was performed to understand the relation between consumer service, internet usefulness, consumer anxiety, and consumer satisfaction, it was found that consumer service, internet usefulness, consumer anxiety had significantly effected on consumer satisfaction. Third, To verify the relation between consumer satisfaction and repurchase-intentions, intentions to spread out, Pearson correlation analysis was used. it was found that consumer satisfaction had positive effect on both intentions. This study has some limitations because of the shorts of money and time. since the sample of this study was consumers who have ever bought one or more products via internet shopping mall, this sample was appropriate. but the major parts of sample were college students, and the sample size was so small. therefore this results should carefully be generalized. For further study, it is required to select more precise samples and to include more variables.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.149-159
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• 1999

Purpose: The purpose of this study was to evaluate cervical lymph node metastasis of oral squamous cell carcinoma patients by MRI film and neural network system. Materials and Methods: The oral squamous cell carcinoma patients(21 patients. 59 lymph nodes) who have visited SNU hospital and been taken by MRI. were included in this study. Neck dissection operations were done and all of the cervical lymph nodes were confirmed with biopsy. In MR images. each lymph node were evaluated by using 6 MR imaging criteria(size. roundness. heterogeneity. rim enhancement. central necrosis, grouping) respectively. Positive predictive value. negative predictive value. and accuracy of each MR imaging criteria were calculated. At neural network system. the layers of neural network system consisted of 10 input layer units. 10 hidden layer units and 1 output layer unit. 6 MR imaging criteria previously described and 4 MR imaging criteria (site I-node level II and submandibular area. site II-other node level. shape I-oval. shape II-bean) were included for input layer units. The training files were made of 39 lymph nodes(24 metastatic lymph nodes. 10 non-metastatic lymph nodes) and the testing files were made of other 20 lymph nodes(10 metastatic lymph nodes. 10 non-metastatic lymph nodes). The neural network system was trained with training files and the output level (metastatic index) of testing files were acquired. Diagnosis was decided according to 4 different standard metastatic index-68. 78. 88. 98 respectively and positive predictive values. negative predictive values and accuracy of each standard metastatic index were calculated. Results: In the diagnosis of using single MR imaging criteria. the rim enhancement criteria had highest positive predictive value (0.95) and the size criteria had highest negative predictive value (0.77). In the diagnosis of using single MR imaging criteria. the highest accurate criteria was heterogeneity (accuracy: 0.81) and the lowest one was central necrosis (accuracy: 0.59). In the diagnosis of using neural network systems. the highest accurate standard metastatic index was 78. and that time. the accuracy was 0.90. Neural network system was more accurate than any other single MR imaging criteria in evaluating cervical lymph node metastasis. Conclusion: Neural network system has been shown to be more useful than any other single MR imaging criteria. In future. Neural network system will be powerful aiding tool in evaluating cervical node metastasis.