• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.59-70
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• 2022

In this paper, we proposed an active fault tolerant control (AFTC) method for the position control of a quadrotor with complete loss of effectiveness of one motor. We obtained the dynamics of a quadrotor using Lagrangian equation without small angle assumption. For detecting the fault on a motor, we designed a fault detection module, which consists of the fault detection and diagnosis (FDD) module and the fault detection and isolation (FDI) module. For the FDD module, we designed a nonlinear observer that observes the states of a quadrotor based on the obtained dynamics. Using the observed states of a quadrotor, we designed residual signals and set the appropriate threshold values of residual signals to detect the fault. Also, we designed an FDI module to identify the fault location using the designed additional conditions. To make a quadrotor track the desired path after detecting the fault of a motor, we designed a fault tolerant controller based on the multiple sliding surface control (MSSC) technique. Finally, through simulations, we verified the effectiveness of the proposed AFTC method for a quadrotor with complete loss of effectiveness of one motor.

• Tuberculosis and Respiratory Diseases
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• v.59 no.5
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• pp.473-479
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• 2005

Background : A pulmonary embolism often presents with nonspecific symptoms and signs. However, a delayed diagnosis can result in catastrophic outcome. The majority of preventable deaths associated with a pulmonary embolism can be ascribed to a missed diagnosis rather than to the failure of existing treatments. Therefore, accurate and rapid diagnostic methods are essential for the management of a pulmonary embolism. The recent generation of multidetector-row spiral CT scanners appears to outperform other imaging modalities in detecting a central and peripheral pulmonary embolism. However, there are some variations in the interpretations of the findings between observers. This study examined the inter-observer differences of the diagnoses in patients with a pulmonary embolism. Method : 64 patients who were diagnosed with a pulmonary embolism either clinically or with spiral chest CT from 2002 to 2004, were included. Two thoracic radiologists interpreted the multidetector-row spiral CT in terms of the diagnosis of a pulmonary embolism and the location of the thrombus independently. Among 64 patients, 14 patients were excluded because there was no evidence of a pulmonary embolism or there was different interpretation of the pulmonary embolism between radiologists. A clinical diagnosis was based on "Rules for predicting the probability of embolism". Results : The mean score of the patients according to the Wells method was $3.91{\pm}0.30$ (0-9). The accordance of the radiologists was 95% in the main, 85% in the lobar, 91.2% in the segmental, and 96% in the sub-segmental pulmonary arteries. After excluding the negative interpretation from both radiologists, their agreement was 76.2%(${\kappa}.$ 0.83) in the main, 57.6%(${\kappa}.$ 0.63) in the lobar, 51.5%(${\kappa}.$ 0.63) in the segmental, and 34.6%(${\kappa}.$ 0.49) in the sub-segmental pulmonary arteries. Conclusion : Chest CT has been recently applied to patients suspected of having a pulmonary embolism. It was found that spiral CT is a rapid test for diagnosing a thrombus, and there was reliable accordance between the observers from the area of the large pulmonary arteries. However, there was a lack of agreement between the observers in diagnosing thrombi located distal to the sub-segmental arteries.

• Journal of the Korean Society of Radiology
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• v.83 no.5
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• pp.1059-1070
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• 2022

Purpose To compare the sensitivity of tumor detection and inter-observer agreement between acquired diffusion-weighted imaging (aDWI) b2000 and computed DWI (cDWI) b2000 in patients with prostate cancer (PCa). Materials and Methods Eighty-eight patients diagnosed with PCa by radical prostatectomy and having undergone pre-operative 3 Tesla-MRI, including DWI (b, 0, 100, 1000, 2000 s/mm²), were included in the study. cDWI b2000 was obtained from aDWI b0, b100, and b1000. Two independent reviewers performed a review of the aDWI b2000 and cDWI b2000 images in random order at 4-week intervals. A region of interest was drawn for the largest tumor on each dataset, and a Prostate Imaging-Reporting and Data System (PI-RADS) score based on PI-RADS v2.1 was recorded. Histologic topographic maps served as the reference standard. Results The study population's Gleason scores were 6 (n = 16), 7 (n = 53), 8 (n = 9), and 9 (n = 10). According to the reviewers, the sensitivities of cDWI b2000 and aDWI b2000 showed no significant differences (for reviewer 1, both 94% [83/88]; for reviewer 2, both 90% [79/88]; p = 1.000, respectively). The kappa values of cDWI b2000 and aDWI b2000 for the PI-RADS score were 0.422 (95% confidence interval [CI], 0.240-0.603) and 0.495 (95% CI, 0.308-0.683), respectively. Conclusion cDWI b2000 showed comparable sensitivity with aDWI b2000, in addition to sustained moderate inter-observer agreement, in the detection of PCa.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.5
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• pp.635-643
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• 2018

This paper propose a method to identify the motor parameters and improve input voltage error which affect the low speed position error of the back-emf(back electromotive force) based sensorless algorithm and to secure the operation reliability and stability even in the case where the load fluctuation is severe and the start and low speed operation frequently occurs. In the model-based observer used in this paper, stator resistance, inductance, and input voltage are particularly influential factors on low speed performance. Stator resistance can cause resistance value fluctuation which may occur in mass production process, and fluctuation of resistance value due to heat generated during operation. The inductance is influenced by the fluctuation due to the manufacturing dispersion and at a low speed where the change of the current is severe. In order to find stator resistance and inductance which have different initial values and fluctuate during operation and have a large influence on sensorless performance at low speed, they are commonly measured through 2-point calculation method by 2-step align current injection. The effect of voltage error is minimized by offsetting the voltage error. In addition, when the command voltage is used, it is difficult to estimate the back-emf due to the relatively large distortion voltage due to the dead time and the voltage drop of the power device. In this paper, we propose a simple circuit and method to detect the voltage by measuring the PWM(Pulse Width Modulation) pulse width and compensate the voltage drop of the power device with the table, thereby minimizing the position error due to the exact estimation of the back-emf at low speed. The suitability of the proposed algorithm is verified through experiment.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.2
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• pp.551-557
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• 2015

Background: Differentiating morphologic features based on hematoxylin-eosin (HE) staining is the most common method to classify pathological subtypes of non-small-cell lung cancer (NSCLC). However, its accuracy and inter-observer reproducibility in pathological diagnosis of poorly differentiated NSCLC remained to be improved. Materials and Methods: We attempted to explore the role of immunohistochemistry (IHC) staining in diagnosing pulmonary squamous cell carcinoma (SQCC) with poorly differentiated features by HE staining or with elevated serum adenocarcinoma-specific tumor markers (AD-TMs). We also compared the difference of epidermal growth factor receptor (EGFR) mutation rate between patients with confirmed SQCC and those with revised pathological subtype. Logistic regression analyses were used to test the association between different factors and diagnostic accuracy. Results: A total of 132 patients who met the eligible criteria and had adequate specimens for IHC confirmation were included. Pathological revised cases in poor differentiated subgroup, biopsy samples and high-level AD-TMs cases were more than those with high/moderate differentiation, surgical specimens and normal-level AD-TMs. Moreover, biopsy sample was a significant factor decreasing diagnostic accuracy of pathological subtype (OR, 4.037; 95% CI 1.446-11.267, p=0.008). Additionally, EGFR mutation rate was higher in patients with pathological diagnostic changes than those with confirmed SQCC (16.7% vs 4.4%, p=0.157). Conclusions: Diagnosis based on HE staining only might cause pathological misinterpretation in NSCLC patients with poor differentiation or high-level AD-TMs, especially those with biopsy samples. HE staining and IHC should be combined as pathological diagnostic standard. The occurrence of EGFR mutations in pulmonary SQCC might be overestimated.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.69-70
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• 2013

IPCC (International Panel on Climate Change) reported that the arctic sea-ice extent has been decreased by 2.7% per decades since satellite observations in 1978. The decreased sea-ice extent has gained an international attention due to its economical benefits from the NSR (Northen Sea Route). The NRS - not a clearly defined single route, but a number of alternative routes across the top of Russiahas a 37 % reduction in sailing distance, comparing to the SSR (Southen Sea Route) passing thourgh the Suez Canal. Sailing days are consequently reduced from 30 days to 20 days. Also, it is estimated that the Northen Sea has 20 to 25% of world's oil resources and occupies 40% of the world's fishery production. As Republic of Korea was admitted as an observer to the Arctic Council on May 15, 2013, there has been increasing needs to explore new route in the Northen Sea. In this situation, Korea Institute of Ocean Science & Technology (KIOST) is preparing a plan for the development of Arctic-circle Ocean Environmental Information System to support the ice navigation and resource exploration in the Arctic. We will introduce a conceptual design of a satellite-based ice navigation supporting system for the northern sea route.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.4
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• pp.193-205
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• 2003

There has been so many research activities about robot soccer system in the many research fields, for example, intelligent control, communication, computer technology, sensor technology, image processing, mechatronics. Especially researchers research strategy for attacking in the field of strategy, and develop intelligent strategy. Then, soccer robots cannot defense completely and efficiently by using simple defense strategy. Therefore, intention extraction of attacker is needed for efficient defense. In this thesis, intention extractor of soccer robots is designed and developed based on FMMNN(Fuzzy Min-Max Neural networks ). First, intention for soccer robot system is defined, and intention extraction for soccer robot system is explained.. Next, FMMNN based intention extractor for soccer robot system is determined. FMMNN is one of the pattern classification method and have several advantages: on-line adaptation, short training time, soft decision. Therefore, FMMNN is suitable for soccer robot system having dynamic environment. Observer extracts attack intention of opponents by using this intention exactor, and this intention extractor is also used for analyzing strategy of opponent team. The capability of developed intention extractor is verified by simulation of 3 vs. 3 robot succor simulator. It was confirmed that the rates of intention extraction each experiment increase.

• Investigative Magnetic Resonance Imaging
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• v.21 no.1
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• pp.9-19
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• 2017

Background: Normalized cerebral blood volume (nCBV) can be measured using manual or semiautomatic segmentation method. However, the difference in diagnostic performance on brain tumor differentiation between differently measured nCBV has not been evaluated. Purpose: To compare the diagnostic performance of manually obtained nCBV to that of semiautomatically obtained nCBV on glioblastoma (GBM) and primary central nervous system lymphoma (PCNSL) differentiation. Materials and Methods: Histopathologically confirmed forty GBM and eleven PCNSL patients underwent 3T MR imaging with dynamic susceptibility contrast-enhanced perfusion MR imaging before any treatment or biopsy. Based on the contrast-enhanced T1-weighted imaging, the mean nCBV (mCBV) was measured using the manual method (manual mCBV), random regions of interest (ROIs) placement by the observer, or the semiautomatic segmentation method (semiautomatic mCBV). The volume of enhancing portion of the tumor was also measured during semiautomatic segmentation process. T-test, ROC curve analysis, Fisher's exact test and multivariate regression analysis were performed to compare the value and evaluate the diagnostic performance of each parameter. Results: GBM showed a higher enhancing volume (P = 0.0307), a higher manual mCBV (P = 0.018) and a higher semiautomatic mCBV (P = 0.0111) than that of the PCNSL. Semiautomatic mCBV had the highest value (0.815) for the area under the curve (AUC), however, the AUCs of the three parameters were not significantly different from each other. The semiautomatic mCBV was the best independent predictor for the GBM and PCNSL differential diagnosis according to the stepwise multiple regression analysis. Conclusion: We found that the semiautomatic mCBV could be a better predictor than the manual mCBV for the GBM and PCNSL differentiation. We believe that the semiautomatic segmentation method can contribute to the advancement of perfusion based brain tumor evaluation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1167-1174
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• 2009

In the monitoring of a patient in a sickroom, not only the physiologic and environmental data of the patient, which is automatically measured, but also the clinical data(clinical chart)of the patient, which is drew up by a doctor or nurse, are recognized as important data. However, since in the current environment of a sickroom, clinical data is collected being divided from the data that is automatically measured, the two data are used without an effective integration. This is because the integration of the two data is difficult due to their different collection times, which leads the reconstruction of clinical data to be remarkably uncertain. In order to solve these problems, a method to synchronize the continuous environmental data of a sickroom and clinical data is appearing as an important measure. In addition, the increase of use of small machines and the development of solutions based on wireless communications provide a communication platform to the developers of health care. Thus, this paper realizes a remote system for taking care of patients based on a web that uses mobile phones. That is, clinical data made by a nurse or doctor and the environmental data of a sick room comes to be collected by a collection module through a wireless sensor network. An observer can see clinical data and the environmental data of a sickroom through his/her mobile phone, integrating and storing his/her data into the database. Families of a patient can see clinical data made by hospital and the environment of the sick room of the patent through their computers or mobile phones outside the hospital. Through the system,hospital can provide better medical services to patients and their families.

• Journal of Korean Clinical Nursing Research
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• v.18 no.2
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• pp.284-295
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• 2012

Purpose: This study was done to clarify effects of bispectral index monitoring sedative administration, compared to MOAA/S (Modified Observer's Assessment of Alertness and Sedation), on conscious sedation, physiological stability and recovery time for patients undergoing endoscopic submucosal dissection. Methods: Participants In this study were patients who underwent endoscopic submucosal dissection because of early gastric cancer. Participants were assigned randomly to an experimental group receiving sedatives based on bispectral index monitoring or to a control group with the MOAA/S instrument. Movements, belching, memory, pain, discomfort, physiological stability (MBP, PR, $SpO_2$), and recovery time were measured during the treatment and recovery. Data were analyzed using Spearman partial correlation coefficient analysis, Mixed model and Wilcoxon rank sum test to determine differences in the parameters. Results: There were no statistically significant differences between the two groups for conscious sedation(movement, belching, memory, pain, or discomfort), physiological stability and recovery time. Conclusion: The results of this study indicate that no differences were found between the two types of monitoring. Thus, use of a bispectral index monitor in clinical practice enabling medical staff to readily assess the conscious sedation of for these patients is expected to be increasingly used as an objective assessment tool for conscious sedation for patient safety.