• 대한원격탐사학회지
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• 제29권6호
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• pp.601-610
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• 2013

As a standard water clarity variable, the vertical underwater visibility, called Secchi depth, is estimated with ocean color satellite data. In the present study, Moderate Resolvtion Imaging Spectradiometer (MODIS) data are used to measure the Secchi depth which is a useful indicator of ocean transparency for estimating the water quality and productivity. To estimate the Secchi depth $Z_v$, the empirical regression model is developed based on the satellite optical data and in-situ data. In the previous study, a semi-analytical algorithm for estimating $Z_v$ was developed and validated for Case 1 and 2 waters in both coastal and oceanic waters using extensive sets of satellite and in-situ data. The algorithm uses the vertical diffuse attenuation coefficient, $K_d$($m^{-1}$) and the beam attenuation coefficient, c($m^{-1}$) obtained from satellite ocean color data to estimate $Z_v$. In this study, the semi-analytical algorithm is validated using temporal MODIS data and in-situ data over the Yellow, Southern and East Seas including Case 1 and 2 waters. Using total 156 matching data, MODIS $Z_v$ data showed about 3.6m RMSE value and 1.7m bias value. The $Z_v$ values of the East Sea and Southern Sea showed higher RMSE than the Yellow Sea. Although the semi-analytical algorithm used the fixed coupling constant (= 6.0) transformed from Inherent Optical Properties (IOP) and Apparent Optical Properties (AOP) to Secchi depth, various coupling constants are needed for different sea types and water depth for the optimum estimation of $Z_v$.

• Advances in nano research
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• 제5권3호
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• pp.245-251
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• 2017

Multiwalled carbon-nanotubes (MWCNT) and micro-structured carbon, such as biochar or activated carbon (AC), have been seen to significantly increase the growth indices of certain plant species such as maize (Zea mays L.). Seed imbibition is the stage where environmental factors that affect water transport across the seed coat barrier, make a large impact. This work explores the effect on water imbibition by maize seeds when the aqueous environment surrounding the seed is diluted by small concentrations (10 and 20 mg/l) of pristine MWCNT (p-MWCNT), carboxylate functionalized MWCNT (COO-MWCNT) and AC. The degree of sensitivity of the process to (i) large structural changes is seen by utilizing the nano (the MWCNT) and the micro (the AC) allotropic forms of carbon; (ii) to small changes in the purity and morphology of the p-MWCNT by utilizing 95% pure and 99% pure p-MWCNTs of slightly differing morphologies; and (iii) to MWCNT functionalization by using highly pure (97%) COO-MWCNT. Water imbibition was monitored over a 15 hour period by Near Infrared Thermography (NIRT) and also by seed weighing. Seed surface topography was seen by SEM imaging. Analysis of the NIRT images suggests rapid seed surface topological changes with the quantity of water imbibed. While further work is necessary to arrive at a conclusive answer, this work shows that the imbibition phase of the maize seed is sensitive to the presence of MWCNT even to small differences in the purity of the p-MWCNT and to small differences in the physicochemical properties of the medium caused by the hydrophilic COO-MWCNT.

• 대한의용생체공학회:의공학회지
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• 제39권3호
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• pp.116-123
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• 2018

This study is a model experimental study using a phantom to propose an optimized brain CT scan protocol that can reduce the radiation dose of a patient and remain quality of image. We investigate the CT scan parameters of brain CT in clinical medical institutions and to measure the important parameters that determine the quality of CT images. We used 52 multislice spiral CT (SOMATOM Definition AS+, Siemens Healthcare, Germany). The scan parameters were tube voltage (kVp), tube current (mAs), scan time, slice thickness, pitch, and scan field of view (SFOV) directly related to the patient's exposure dose. The CT dose indicators were CTDIvol and DLP. The CT images were obtained while increasing the imaging conditions constantly from the phantom limit value (Q1) to the maximum value (Q4) for AAPM CT performance evaluation. And statistics analyzed with Pearson's correlation coefficients. The result of tube voltage that the increase in tube voltage proportionally increases the variation range of the CT number. And similar results were obtained in the qualitative evaluation of the CT image compared to the tube voltage of 120 kVp, which was applied clinically at 100 kVp. Also, the scan conditions were appropriate in the tube current range of 250 mAs to 350 mAs when the tube voltage was 100 kVp. Therefore, by applying the proposed brain CT scanning parameters can be reduced the radiation dose of the patient while maintaining quality of image.

• 전자공학회논문지
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• 제53권9호
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• pp.137-142
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• 2016

컴퓨터단층촬영(CT) 검사의 정맥주사(IV)시 조영제의 혈관외유출은 조직손상을 유발할 수 있다. Bolus tracking 시스템을 이용하여 조영제를 주입과정에서 발생하는 혈관외유출을 검출한다. 또한 조직손상을 방지하기 위하여 MPR 및 VR 영상을 이용하여 혈관외유출을 검출하였다. 조영제의 혈관외유출을 검출하기 위하여 16MDCT, 64MDCT를 사용하였다. 혈관외유출에 대한 3차원영상은 환자치료에 중요한 치료정보를 제공할 수 있다. 또한 조영제와 조직 간의 선예도를 개선하기 위해서 edge enhancement 영상처리기법을 적용하였고, 선예도 및 대조도가 개선되었다.

• Radiation Oncology Journal
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• 제35권1호
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• pp.65-70
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• 2017

Purpose: To evaluate the utility of implanted surgical clips for detecting interfractional errors in the treatment of hepatobiliary and pancreatic cancer with postoperative radiotherapy (PORT). Methods and Materials: Twenty patients had been treated with PORT for locally advanced hepatobiliary or pancreatic cancer, from November 2014 to April 2016. Patients underwent computed tomography simulation and were treated in expiratory breathing phase. During treatment, orthogonal kilovoltage (kV) imaging was taken twice a week, and isocenter shifts were made to match bony anatomy. The difference in position of clips between kV images and digitally reconstructed radiographs was determined. Clips were consist of 3 proximal clips (clip_p, ${\leq}2cm$) and 3 distal clips (clip_d, >2 cm), which were classified according to distance from treatment center. The interfractional displacements of clips were measured in the superior-inferior (SI), anterior-posterior (AP), and right-left (RL) directions. Results: The translocation of clip was well correlated with diaphragm movement in 90.4% (190/210) of all images. The clip position errors greater than 5 mm were observed in 26.0% in SI, 1.8% in AP, and 5.4% in RL directions, respectively. Moreover, the clip position errors greater than 10 mm were observed in 1.9% in SI, 0.2% in AP, and 0.2% in RL directions, despite respiratory control. Conclusion: Quantitative analysis of surgical clip displacement reflect respiratory motion, setup errors and postoperative change of intraabdominal organ position. Furthermore, position of clips is distinguished easily in verification images. The identification of the surgical clip position may lead to a significant improvement in the accuracy of upper abdominal radiation therapy.

• 한국항공우주학회지
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• 제30권6호
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• pp.124-129
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• 2002

한국과학기술원 인공위성연구센터는 우리별 1, 2, 3호의 성공적인 개발 및 발사에 이어 2003년 발사예정으로 과학위성 1호를 개발하고 있다. 과학위성 1호는 주탑재체로 원자외선분광기와 우주플라즈마 관측시스템을 탑재하고 있으며, 우리별 1, 2, 3호의 기술적 유산인 박스형태의 적층식 기계수조로 설계되어 있다. 현재 과학위성 1호는 인증모델의 설계 및 제작과 인증수준의 열진공시험 및 발사환경시험을 성공적으로 마친 상태이다. 본 논문에서는 과학위성 1호 인증모델을 기계구조시스템을 중심으로 소개하고, 발사환경시험 결과를 보고한다.

• Imaging Science in Dentistry
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• 제42권3호
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• pp.155-161
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• 2012

Purpose: This study was performed to investigate the prevalence, morphology, and calcification pattern of the elongated styloid process in the Mathura population and its relation to gender, age, and mandibular movements. Materials and Methods: The study analyzed digital panoramic radiographs of 2,706 adults. The elongated styloid process was classified with the radiographic appearance based on the morphology and calcification pattern. The limits of mandibular protrusion were evaluated for each subject. The data were analyzed by using a Student's t-test and chi-squared test with significance set at p=0.05. Results: Bilateral elongation having an "elongated" type styloid process with a "partially mineralized" pattern was the most frequent type of styloid process. No correlation was found between styloid process type and calcification pattern on the one hand and gender on the other, although elongated styloid was more prevalent in older and male populations (p<0.05). Further styloid process elongation showed no effect on mandibular protrusive movement (p>0.05). Conclusion: Dentists should recognize the existence of morphological variation in elongated styloid process or Eagle syndrome apparent on panoramic radiographs. We found higher prevalence of elongated styloid process in the population of the Mathura region when compared with other Indian populations. The calcification of the styloid process was more common in the older age group with no correlation to gender, mandibular movement and site. "Type I" with a "partially calcified" styloid process was observed more frequently in the population studied.

• 한국의학물리학회지:의학물리
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• 제13권3호
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• pp.139-148
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• 2002

The measured attenuation correction with transmission (Tx) scans produced quantitatively accurate images. However, it was not clear for optimal emission (Ex) and Tx scan time in PET imaging. This study was to evaluate acceptable Ex and Tx scan time by simulating clinical situations using various phantoms. Cylindrical and NEMA phantom were used for $^{18}$ F-PET scan using 2D protocol in GE Advance PETTM scanner. Cylindrical phantom was filled with 136 MBq 18F, and five regions of interests (ROI) were drawn on 23 slices. NEMA phantom had three inserts containing water, air and polytetrafluoro-ethylene (PTFE). Outside of these inserts were filled with 309 MBq of $^{18}$ F, and total 12 ROIs were drawn on 23 slices. Scans were carried out according to five Ex scan times: 2, 5, 10, 15, and 30 min, and nine Tx scan times: 2, 3, 4, 5, 7, 10, 15, 20, and 30 min. Images were reconstructed using measured attenuation correction, and ROI analyses were performed for all images, and mean, standard deviation (SD), coefficient of variation and percent errors were calculated. For cylindrical phantom study, ROI mean and SD were decreased as Ex and Tx time increased. Coefficients of variation were kept constant, when Tx was greater than 10 min. The amount of error decreased for the increment of Ex time from 10 min to 15 min was almost the same to that from 15 min to 30 min. In NEMA phantom Tx 15 min showed the lowest er개r level when the percent errors for three inserts were summed for all of the Ex times. This study suggested that Ex 15 min and Tx 15 min were acceptable as optimal scan time for the scanning protocol and the dose of radiopharmaceuticals used in these phantom study.

• 한국한의학연구원논문집
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• 제4권1호통권4호
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• pp.27-45
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• 1998

$\ulcorner$Euibangyoochui醫方類聚$\lrcorner$ (1445) is regarded as a treasure-house of the knowledge of traditional oriental medicine which contains over 50,000 prescriptions and enormerous amount of medical information. Despite the importance and information contained in this book, it has been rarely used since it was not convenient to use this book. In this study, therefore, the establishment of database on $\ulcorner$Euibangyoochui$\lrcorner$ was carried out. Before the database establishment of $\ulcorner$Euibangyoochui$\lrcorner$ , basic works such as correction, interpretation, proofreading and translation of original text should be done. The results obtained in this study are summaried as follows : 1) During the course of studying the original text of $\ulcorner$Euibangyoochui$\lrcorner$ , the editing process and transmission of medical books in early Chosun dynasty was figured out. 2) For better correction, interpretation, proofreading and translation of $\ulcorner$Euibangyoochui$\lrcorner$ , $\ulcorner$Euibangyoochui$\lrcorner$ microfilms which are the collection of Japanese Royal Library (宮內廳 圖書寮) were obtained in this study. Through this process, the errors in the republication were able to be corrected. 3) Analyzing the organization and compilatory method of $\ulcorner$Euibangyoochui$\lrcorner$ is one of the basic requirements of understanding the scale of the whole. book and establishing database as a result. So the analysis results were used for the basic structuring of database. 4) $\ulcorner$Euibangyoochui$\lrcorner$ CD- ROM was designed in a way that the images of microfilms, original text and Korean translation can be compared by 3-D device. In addition, the convenience and proficiency of imaging the information and prescriptions of the text is one of the remarkable features of this CD-ROM.

• 대한방사선기술학회지:방사선기술과학
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• 제44권3호
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• pp.205-210
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• 2021

The purpose of this study was to analyze the spatial dose according to the distance by location of medical workers when using a mobile X-ray fluoroscopy device in the operating room through a simulation experiment. The MCNPX program was used for the simulation, and the location of medical workers was set around the operating table, and the spatial dose distribution according to the distance and changes in imaging conditions was evaluated. As a result, The highest score was 2.74×10^-4 mGy, 2.72×10^-4 mGy, and 1.18×10^-4 mGy based on the 10 cm distance from the operating table. Spatial dose depending on the distance 100cm, A point 5.15×10^-5 mGy is decreased 19% of 10cm, D point 5.12×10^-5 mGy, 19 % of 10cm, and G pint, 1.73×10^-5 mGy is reduced by 15% of 10cm. Based on this study, medical-related workers directly or indirectly participating in surgery carry potential risks of radiation exposure during surgery, but there are difficulties in radiation protection due to the nature of their work. Therefore, efforts to reduce exposure suitable for the operating room environment will be required.