• Safety and Health at Work
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• v.13 no.3
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• pp.326-335
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• 2022

Background: One of the important actions for enhancing human reliability in any industry is assessing human error probability (HEP). The HEART technique is a robust tool for calculating HEP in various industries. The traditional HEART has some weaknesses due to expert judgment. For these reasons, a hybrid model is presented in this study to integrate HEART with Best-Worst Method. Materials Method: In this study, the blasting process in an iron ore mine was investigated as a case study. The proposed HEART-BWM was used to increase the sensitivity of APOA calculation. Then the HEP was calculated using conventional HEART formula. A consistency ratio was calculated using BWM. Finally, for verification of the HEART-BWM, HEP calculation was done by traditional HEART and HEART-BWM. Results: In the view of determined HEPs, the results showed that the mean of HEP in the blasting of the iron ore process was 2.57E-01. Checking the full blast of all the holes after the blasting sub-task was the most dangerous task due to the highest HEP value, and it was found 9.646E-01. On the other side, obtaining a permit to receive and transport materials was the most reliable task, and the HEP was 8.54E-04. Conclusion: The results showed a good consistency for the proposed technique. Comparing the two techniques confirmed that the BWM makes the traditional HEART faster and more reliable by performing the basic comparisons.

• Journal of the Korean Data and Information Science Society
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• v.28 no.3
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• pp.709-720
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• 2017

In healthcare and medical research, many important variables have a measurement error such as body mass index and laboratory data. It is also not easy to collect samples of large size because of high cost and long time required to collect the target patient satisfied with inclusion and exclusion criteria. Beside, the demand for solving a complex scientific problem has highly increased so that a semiparametric regression approach could be of substantial value solving this problem. To address the issues of measurement error, small domain and a scientific complexity, we conduct a multivariable Bayesian smoothing under structural measurement error covariate in this article. Specifically we enhance our previous model by incorporating other useful auxiliary covariates free of measurement error. For the regression spline, we use a radial basis functions with fixed knots for the measurement error covariate. We organize a fully Bayesian approach to fit the model and estimate parameters using Markov chain Monte Carlo. Simulation results represent that the method performs well. We illustrate the results using a national survey data for application.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1362-1364
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• 1996

In this paper a Dear lossless compression of medical images with vector quantizer is proposed. In order to apply the vector quantizer to medical images, the peak error in the reconstructed image is reduced down to 1. Simulation results show that the proposed coding scheme provides better performance with a PSNR improvement compared to the conventional JPEG standard.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2002.11a
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• pp.59-62
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• 2002

Wavelength selection and prediction algorithm for determining hematocrit are investigated. A model based on the difference in optical density induced by the pulsation of heart beat is developed by taking approximation of Twersky's theory on the assumption that the variation of blood vessel size is small during arterial pulsing[1]. A device is constructed with a five-wavelength LED array as light source. The selected wavelengths are two isobestic points and three in compensation for tissue scattering. Data are collected from 549 out-patients who are randomly grouped as calibration and prediction sets. The range of percent hematocrit was 19.3∼51.8. The ratio of the variations of optical density between systole and diastole at two different wavelengths is used as a variable. We selected several such variables that show high reproducibility among all variables. Multiple linear regression analysis is made. The relative percent error is 8% and the standard deviation is 3.67 for the calibration set. The relative % error and standard deviation of the prediction set are 8.2% and 3.69 respectively. We successfully demonstrate the possibility of non-invasive hematocrit measurement, particularly, using the wavelengths below 1000nm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.513-516
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• 2013

In this paper, we present an information collecting system in medical information management domain. Our proposed system performs a systemized process, consisting of collection, transmission, and management, to develop intelligent medical information system and medical big data processing system. Our information collecting system consists of low-power biomedical sensors, biomedical information collecting devices, and storage systems. Currently, almost biomedical information of patients is collected manually by employees like nurses and medical doctors. Therefore, collected biometric data can be error-pronoun data. Since there is a lack to make big data of medical information, it is difficult to enhance the quality of medical services and researches. Accordingly, through our proposed system, we can overcome the problems like error-pronoun biometric data. In addition, we can extremely extend the area of collectable biometric data. Furthermore, using this system, we are able to make a real-time biomedical analysis system, like a real-time patient diagnosis system, and establish a strategy to against future medical markets changing rapidly.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.144-145
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• 2002

Stereotactic radiotherapy is required to irradiate a small tumor accurately. The radiotherapy showing improves when making an accidental error little boundlessly. It is performed according to treatment planning that is established by the outside landmark of head. At present, when stereotactic radiotherapy for a head is done, the Leksell Flame is fixed on the head, and positioning based on the point and so on which it is in that fixed implement is performed. However, there are problems on the method done at present in the point such as reappearance when the fractionated irradiation method in which the Leksell Flame is removed and installed at every treatment is done because there are landmarks outside the head. Landmarks in the skull were decided, and that precision was examined for the purpose of the improvement of the radiation therapeutic gain. Linac-graphy with longitudinal and lateral view were taken with 6 MV photon beams. A distance to base point inside the skull, each film measured the angle from a center of the small irradiation field, and comparison was done. From the results, a large accidental error wasn't seen as a result of the measurement by every film. Stereotactic radiotherapy for a head treatment had an accidental error of about several millimeters when treatment positioning was done. Therefore, it was thought that there was no problem about an accidental error to arise by putting a landmark in the skull. And, because an accidental error was easy to discover, we thought that modification could be done easily. It was suggested that a landmark in the skull on thus study were useful for improvement of stereotactic radiotherapy.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.5
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• pp.231-240
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• 2015

Medical imagery require to protect the privacy with preserving the quality of the original contents. Therefore, reversible watermarking is a solution for this purpose. Previous researches have focused on general imagery and achieved high capacity and high quality. However, they raise a distortion over entire image and hence are not applicable to medical imagery which require to preserve the quality of the objects. In this paper, we propose a novel reversible watermarking for medical imagery, which preserve the quality of the objects and achieves high capacity. First, object and background region is segmented and then predicted error histogram-based reversible watermarking is applied for each region. For the efficient watermark embedding with small distortion in the object region, the embedding level at object region is set as low while the embedding level at background region is set as high. In experiments, the proposed algorithm is compared with the previous predicted error histogram-based algorithm in aspects of embedding capacity and perceptual quality. Results support that the proposed algorithm performs well over the previous algorithm.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.2
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• pp.85-95
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• 2010

Purpose: The degradation of an image quality and error of the beam dose calculation can be caused because the metal artifact is generated during the CT simulation of head and neck patient. The usability of the gantry tilt scan for reducing the metal artifact tries to be appraised. Materials and Methods: The inferior $20^{\circ}$ gantry tilt scan was made in order to reduce the metal artifact and $0^{\circ}$ reconstruction image was acquired. The AAPM CT performance Phantom was used in order to compare the CT number of the reconstructed image and Original image. the difference of volume was compared by using the acrylic phantom. The homogeneity of the CT number was evaluated the Intensity volume Histogram (IVH) as in order to evaluate an influence by the metal artifact. A dose was evaluated as the Dose Volume Histogram (DVH). Results: in the comparison of the CT number and volume, the difference showed up less than 0.5%. As to the comparison of IVH, in the gantry tilt scan, influence by an artifact was reduced and the homogeneity of the CT number was improved. The comparison of DVH result reduced the mean dose error of the both sides parotid 0.2~6%. Conclusion: In the Head & Neck radiation therapy, It is difficult and to distinguish tumor and normal tissue and the error of dose is generated by the metal artifact. The delineation of the exact organization was possible if the Gantry tilt scan was used. The CT number homogeneity was improved and the error of dose could be reduced. The Gantry tilt scan confirmed in the Head & Neck radiation therapy to be very useful in the exact radiation therapy.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.41-41
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• 2003

Purpose: Even if the wedge filter is widely used for the radiation therapy to modify the photon beam intensity, the wedged photon beam dose calculation is not so easy. Radiation therapy planning systems (RTPS) have been used the empirical or semi-analytical methods such as attenuation method using wedge filter parameters or wedge filter factor obtained from measurement. However, these methods can cause serious error in penumbra region as well as in edge region. In this study, we propose the dose calculation algorithm for wedged field to minimize the error especially in the outer beam region. Materials and Method: Modified intensity by wedge filter was calculated using tissue-maximum ratio (TMR) and scatter-maximum ratio (SMR) of wedged field. Profiles of wedged and non-wedged direction was also used. The result of new dose calculation was compared with measurement and the result from attenuation method. Results: Proposed algorithm showed the good agreement with measurement in the high dose-gradient region as well as in the inner beam region. The error was decreased comparing to attenuation method. Conclusion: Although necessary beam data for the RTPS commissioning was increased, new algorithm would guarantee the improved dose calculation accuracy for wedged field. In future, this algorithm could be adopted in RTPS.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.446-449
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• 2002

The video based electronic portal imaging device (EPID), which could display the portal image in near real time, was implemented to verify treatment position error in FSRT(Fractionated Stereotatic Radiation Therapy) instead of a portal film. Also, Developed FSRT system was composed of the stereotactic frame, frame mounting system and collimator cones. The verification of treatment position is very crucial in special therapies like FSRT. In general, the FSRT uses high dpse rate at small field size for treating small intracranial lesions. To evaluate quantitative positioning errors in FSRT, we used the first FSRT image as reference image and obtained the second FSRT image that was moved 2mm intentionally and detected intracranial contours after image processing. The generated 2mm error could be verified by overlapping only contours of two images. Through this study, the radiation treatment efficiency could be improved by performing precise radiation therapy with a developed video based EPID and FSRT.