• Safety and Health at Work
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• 제13권3호
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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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• 제28권3호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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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.

• 한국근적외분광분석학회:학술대회논문집
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• 한국근적외분광분석학회 2002년도 강연요지집
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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.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.513-516
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• 2013

본 논문에서는 지능화된 의료 정보 시스템 구축 및 의료 빅 데이터 처리를 위한 생체 정보의 수집, 전송, 관리와 같은 일련의 체계화된 의료 정보 시스템의 구현 및 설계를 제공한다. 본 논문에서 제시하는 의료 정보 시스템은 소형화 및 저 전력화된 생체 정보 수집 센서와 이를 단계적으로 수집하여 중앙 의료 정보 시스템으로 전송하는 데이터 정보 전송 장치 및 저장 장치로 구성되어 있다. 기존 의료 정보 구축 환경은 간호사나 의사의 수기 작성에 의한 수집 및 비 자동화된 방법에 의한 구축으로 관리되어짐에 따라 장기적 관점에서의 의료 품질 향상 및 연구가 불가능하였다. 하지만, 본 논문에서 제시하는 의료 정보 수집 시스템을 통하여 인적 오류 극복 및 정보 수집 범위의 극대화를 추구할 수 있다. 더 나아가, 실시간 의료 정보 빅 데이터 분석 시스템과의 결합을 통해 환자 상태 분석 및 처방과 의료 품질 개선 전략 수립을 가능케 하며, 의료 정보 네트워크 구축을 통해 대형화 되어가는 의료 시장에 빠르게 대처할 수 있다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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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.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제4권5호
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• pp.231-240
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• 2015

의료 영상은 원본 콘텐츠의 품질을 유지하는 것이 중요한 동시에 사생활 보호의 요구가 증가함에 따라서 가역 워터마킹 기술에 대한 필요성이 증가하고 있다. 기존의 가역 워터마킹 알고리즘은 의료 영상이 아닌 일반 영상에서는 고용량 고품질을 유지할 수 있으나 영상 전체에 왜곡을 야기한다. 따라서 촬영 대상물의 품질 유지가 중요한 의료 영상에 직접적으로 적용하기에는 부적합하다는 단점을 가진다. 본 논문에서는 의료 영상의 촬영 대상물 영역의 영상 품질을 유지하며, 워터마크를 효율적으로 삽입할 수 있는 가역 워터마킹 알고리즘을 제안한다. 먼저 대상물과 배경 영역을 분할하기 위한 알고리즘을 설계하고, 그 후에 분할된 대상물과 배경에 대해 추정오차 히스토그램에 기반하여 가역 워터마킹 기법을 적용한다. 대상물 영역에는 삽입 레벨을 낮게 설정하고, 배경 영역에 삽입 레벨을 높게 설정함으로써 대상물의 화질은 최소한으로 변형을 하며 효율적인 삽입이 가능하도록 하였다. 실험에서 다양한 의료 영상에 대하여 제안한 알고리즘을 기존 추정오차 히스토그램 기반 가역 워터마킹 기술과 삽입 용량 및 영상 품질에 대한 비교를 수행하였고, 그 결과 제안하는 알고리즘이 기존 알고리즘에 비해 높은 영상 품질을 유지하면서 우수한 삽입 용량을 얻을 수 있었다.

• 대한방사선치료학회지
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• 제22권2호
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• pp.85-95
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• 2010

목 적: 두경부 환자의 CT simulation시 metal artifact가 발생하여 영상의 질 저하와 선량계산의 오차를 유발 할 수 있어 metal artifact를 줄이기 위한 gantry tilt scan의 유용성을 평가하고자 한다. 대상 및 방법: Metal artifact를 줄이기 위하여 $20^{\circ}$ gantry tilt scan하여 $0^{\circ}$로 재구성한 이미지를 획득하였다. AAPM CT performance Phantom을 이용하여 CT number를 비교 분석하고, 아크릴 팬텀을 이용하여 체적의 일치여부를 확인하였다. Metal artifact에 의한 영향을 평가하기 위해 Intensity volume Histogram (IVH)을 통한 CT number의 균질성 및 Dose Volume histogram (DVH)을 통한 선량평가를 시행하였다. 결 과: CT number와 체적의 비교에서는 차이가 0.5% 이하로 나타났다. IVH를 비교 분석결과 gantry tilt scan에서 artifact에 의한 영향이 감소되어 CT number의 균질도가 향상되고, DVH 비교결과는 양쪽 이하선의 0.2~6%의 평균선량 오차를 감소시켰다. 결 론: Head & Neck 방사선치료 시 metal artifact 때문에 체표윤곽의 구별이 어렵고 선량의 오차가 발생한다. Gantry tilt scan을 이용하면 정확한 조직의 묘사가 가능하고, CT number 균질도가 향상되어 선량의 오차를 줄일 수 있었다. Gantry tilt scan 은 Head & Neck 방사선치료 시 정확한 방사선치료에 매우 유용함을 확인하였다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2003년도 제27회 추계학술대회
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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.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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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.