• Progress in Medical Physics
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• v.14 no.4
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• pp.218-224
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• 2003

Purpose：By evaluating the dependence of the tray transmission factor (tray factor) on collimator setting and tray thickness, we determined the validity of the clinically used single tray factor for standard radiation field size (10${\times}$10 $\textrm{cm}^2$). Methods and Materials：For each X ray energies (6 and 10 MV), outputs were measured by using 5 steps of tray thickness (0, 6, 8, 10, 12 mm) and 7 steps of radiation field size (5${\times}$5, 10${\times}$10, 15${\times}$15, 20${\times}$20, 25${\times}$25, 30${\times}$30, 35${\times}$35 $\textrm{cm}^2$) at 10 cm phantom depth. Outputs were measured in both 'with tray' and 'without tray' conditions by using radiation with the same monitor units, and the tray factors were determined by the ratios of the two outputs. To evaluate the validity of a single tray factor obtained for standard radiation field, we analyzed the pattern of the field sizes in cases treated at our hospital in 2002. Results : In the 6 MV X-ray, the increases in the tray factor between the standard field (l0${\times}$10 $\textrm{cm}^2$) and the largest field (35${\times}$35 $\textrm{cm}^2$) were 0.517%, 0.835%, 1.058%, 1.066% in 6, 8, 10, and 12 mm thickness tray, respectively. In the 10 MV X-ray, the increases in the fray factor between the standard field (10${\times}$10 $\textrm{cm}^2$) and the largest field (35${\times}$35 $\textrm{cm}^2$) were 0.517%, 0.836%, 1.058%, 1.066% in 6, 8, 10, 12 mm thickness tray, respectively. In a major portion of clinical cases, when the field size was smaller than 20${\times}$20 $\textrm{cm}^2$, the tray factor was in good agreement with the standard tray factor. However, in cases where the field sizes were 30${\times}$30 $\textrm{cm}^2$ and 35${\times}$35 $\textrm{cm}^2$, the error could exceed 1.0%. Conclusion：The tray factor increased with increasing field size or decreasing tray thickness. The difference of tray factor between the small field and the large field increased with increasing tray thickness. Furthermore, the standard tray factor was valid in most clinical cases except for when the field size was greater than 30${\times}$30 $\textrm{cm}^2$, wherein the error could exceed 1.0%.

• Journal of Chest Surgery
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• v.39 no.5 s.262
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• pp.354-358
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• 2006

Background: Pulsatile pumps for extracorporeal circulation have been known to be better for tissue perfusion than non-pulsatile pumps but be detrimental to blood corpuscles. This study is intended to examine the risks and benefits of $T-PLS^{TM}$ through the comparison of clinical effects of $T-PLS^{TM}$ (pulsatile pump) and $Bio-pump^{TM}$ (non-pulsatile pump) used for coronary bypass surgery. Material and Method: The comparison was made on 40 patients who had coronary bypass using $T-PLS^{TM}\;and\;Bio-pump^{TM}$ (20 patients for each) from April 2003 to June 2005. All of the surgeries were operated on pump beating coronary artery bypass graft using cardiopulmonary extra-corporeal circulation. Risk factors before surgery and the condition during surgery and the results were compared. Result: There was no significant difference in age, gender ratio, and risk factors before surgery such as history of diabetes, hypertension, smoking, obstructive pulmonary disease, coronary infarction, and renal failure between the two groups. Surgery duration, hours of heart-lung machine operation, used shunt and grafted coronary branch were little different between the two groups. The two groups had a similar level of systolic arterial pressure, diastolic arterial pressure and mean arterial pressure, but pulse pressure was measured higher in the group with $T-PLS^{TM}\;(46{\pm}15\;mmHg\;in\;T-PLS^{TM}\;vs\;35{\pm}13\;mmHg\;in\;Bio-pump^{TM},\;p<0.05)$. The $T-PLS^{TM}$-operated patients tended to produce more urine volume during surgery, but the difference was not statistically significant $(9.7{\pm}3.9\;cc/min\;in\;T-PLS^{TM}\;vs\;8.9{\pm}3.6\;cc/min\;in\;Bio-pump^{TM},\;p=0.20)$. There was no significant difference in mean duration of respirator usage and 24-hour blood loss after surgery between the two groups. Plasma free Hb was measured lower in the group with $T-PLS^{TM}\;(24.5{\pm}21.7\;mg/dL\;in\;T-PLS^{TM}\;versus\;46.8{\pm}23.0mg/dL\;in\;Bio-pump^{TM},\;p<0.05)$. There was no significant difference in coronary infarction, arrhythmia, renal failure and morbidity rate of cerebrovascular disease. There was a case of death after surgery (death rate of 5%) in the group tested with $T-PLS^{TM}$, but the death rate was not statistically significant. Conclusion: Coronary bypass was operated with $T-PLS^{TM}$ (Pulsatile flow pump) using a heart-lung machine. There was no unexpected event caused by mechanical error during surgery, and the clinical process of the surgery was the same as the surgery for which $Bio-pump^{TM}$ was used. In addition, $T-PLS^{TM}$ used surgery was found to be less detrimental to blood corpuscles than the pulsatile flow has been known to be. Authors of this study could confirm the safety of $T-PLS^{TM}$.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.1
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• pp.61-69
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• 2008

Purpose: Micro-pinhole SPECT system with conventional multiple-head gamma cameras has the advantage of high magnification factor for imaging of rodents. However, several geometric factors should be calibrated to obtain the SPECT image with good image quality. We developed a simplified geometric calibration method for rotating triple-head pinhole SPECT system and assessed the effects of the calibration using several phantom and rodent imaging studies. Materials and Methods: Trionix Triad XLT9 triple-head SPECT scanner with 1.0 mm pinhole apertures were used for the experiments. Approximately centered point source was scanned to track the angle-dependent positioning errors. The centroid of point source was determined by the center of mass calculation. Axially departed two point sources were scanned to calibrate radius of rotation from pinhole to center of rotation. To verify the improvements by the geometric calibration, we compared the spatial resolution of the reconstructed image of Tc-99m point source with and without the calibration. SPECT image of micro performance phantom with hot rod inserts was acquired and several animal imaging studies were performed. Results: Exact sphere shape of the point source was obtained by applying the calibration and axial resolution was improved. Lesion detectibility and image quality was also much improved by the calibration in the phantom and animal studies. Conclusion: Serious degradation of micro-pinhole SPECT images due to the geometric errors could be corrected using a simplified calibration method using only one or two point sources.

• Progress in Medical Physics
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• v.22 no.4
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• pp.190-197
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• 2011

Currently, the dose distribution calculation used by commercial treatment planning systems (TPSs) for high-dose rate (HDR) brachytherapy is derived from point and line source approximation method recommended by AAPM Task Group 43 (TG-43). However, the study of Monte Carlo (MC) simulation is required in order to assess the accuracy of dose calculation around three-dimensional Ir-192 source. In this study, geometry factor was calculated using segmented sources integration method by dividing microSelectron HDR Ir-192 source into smaller parts. The Monte Carlo code (MCNPX 2.5.0) was used to calculate the dose rate $\dot{D}(r,\theta)$ at a point ($r,\theta$) away from a HDR Ir-192 source in spherical water phantom with 30 cm diameter. Finally, anisotropy function and radial dose function were calculated from obtained results. The obtained geometry factor was compared with that calculated from line source approximation. Similarly, obtained anisotropy function and radial dose function were compared with those derived from MCPT results by Williamson. The geometry factor calculated from segmented sources integration method and line source approximation was within 0.2% for $r{\geq}0.5$ cm and 1.33% for r=0.1 cm, respectively. The relative-root mean square error (R-RMSE) of anisotropy function obtained by this study and Williamson was 2.33% for r=0.25 cm and within 1% for r>0.5 cm, respectively. The R-RMSE of radial dose function was 0.46% at radial distance from 0.1 to 14.0 cm. The geometry factor acquired from segmented sources integration method and line source approximation was in good agreement for $r{\geq}0.1$ cm. However, application of segmented sources integration method seems to be valid, since this method using three-dimensional Ir-192 source provides more realistic geometry factor. The anisotropy function and radial dose function estimated from MCNPX in this study and MCPT by Williamson are in good agreement within uncertainty of Monte Carlo codes except at radial distance of r=0.25 cm. It is expected that Monte Carlo code used in this study could be applied to other sources utilized for brachytherapy.

• Journal of Agricultural Extension & Community Development
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• v.21 no.2
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• pp.1-28
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• 2014

Private consulting firms that are currently participating in rural area development projects with a bottom-up approach are involved in nearly all areas of rural area development, and the policy environment that emphasizes the bottom-up approach will further expand their participation. Reviews of private consulting firms, which started out with high expectations in the beginning, are now becoming rather negative. Expertise is the key issue in the controversy over private consulting firms, and the analysis tends to limit the causes of the problems within firms. This study was conducted on the premise that the fixation on cause and structure results in policy issues in the promotion process. That is because the government authorities are responsible for managing and supervising the implementation of policies, not developing the policies. The current issues with consulting firms emerged because of the hasty implementation of private consulting through the government policy trend without sufficient consideration, as well as the policy environment that demanded short-term outcomes even though the purpose of bottom-up rural area development lies in the ideology of endogenous development focused on the changes in residents' perceptions. Research was conducted to determine how the problems of private consulting firms that emerged and were addressed in this context influenced the consulting market, using current data and based on the firms' business performance. In analyzing the types, firms were divided into three groups: top performers including market leaders (9), excellent performers (36), and average performers (34). An analysis of the correlation between the business performance of each type and managerial resources such as each firm's expertise revealed that there was only a correlation between human resources and regional development in excellent performers, and none was found with the other types. These results imply that external factors other than a firm's capabilities (e.g., expertise) play a significant role in the standards of selecting private consulting firms. Thus, government authorities must reflect on their error of hastily adopting private consulting firms without sufficient consideration and must urgently establish response measures.

• Korean Journal of Remote Sensing
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• v.28 no.1
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• pp.69-77
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• 2012

Surface insolation is one of the major indicators for climate research over the Earth system. For the climate research, long-term data and wide range of spatial coverage from the data observed by two or more of satellites of the same orbit are needed. It is important to improve the continuity and consistency of the derived products, such as surface insolation, from different satellites. In this study, surface insolations based on Geostationary Operational Environmental Satellite (GOES-9) and Multi-functional Transport Satellites (MTSAT-1R) were compared during overlap period using physical model of insolation to find ways to improve the consistency and continuity between two satellites through comparison of each channel data and ground observation data. The thermal infrared brightness temperature of two satellites show a relatively good agreement between two satellites : rootmean square error (RMSE)=5.595 Kelvin; Bias=2.065 Kelvin. Whereas, visible channels shown a quite different values, but it distributed similar tendency. And the surface insolations from two satellites are different from the ground observation data. To improve the quality of retrieved insolations, we have reproduced surface insolation of each satellite through adjustment of the Cloud Factor, and the Cloud Factor for GOES-9 satellite is modified based on the analysis result of difference channel data. As a result, the insolations estimated from GOES-9 for cloudy conditions show good agreement with MTSAT-1R and ground observation : RMSE=$83.439W\;m^{-2}$ Bias=$27.296W\;m^{-2}$. The result improved accuracy confirms that the modification of Cloud Factor for GOES-9 can improve the continuity and consistency of the insolations derived from two or more satellites.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.4
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• pp.209-221
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• 2006

The purpose of this study is to analyze the effects of climate change on the nonpoint source pollution in a small watershed using a mid-range model. The study area is a basin in a rural area that covers 384 ha with a composition of 50% forest and 19% paddy. The hydrologic and water quality data were monitored from 1996 to 2004, and the feasibility of the GWLF (Generalized Watershed Loading function) model was examined in the agricultural small watershed using the data obtained from the study area. As one of the studies on climate change, KEI (Korea Environment Institute) has presented the monthly variation ratio of rainfall in Korea based on the climate change scenario for rainfall and temperature. These values and observed daily rainfall data of forty-one years from 1964 to 2004 in Suwon were used to generate daily weather data using the stochastic weather generator model (WGEN). Stream runoff was calibrated by the data of $1996{\sim}1999$ and was verified in $2002{\sim}2004$. The results were determination coeff, ($R^2$) of $0.70{\sim}0.91$ and root mean square error (RMSE) of $2.11{\sim}5.71$. Water quality simulation for SS, TN and TP showed $R^2$ values of 0.58, 0.47 and 0.62, respectively, The results for the impact of climate change on nonpoint source pollution show that if the factors of watershed are maintained as in the present circumstances, pollutant TN loads and TP would be expected to increase remarkably for the rainy season in the next fifty years.

• Journal of the Korean Wood Science and Technology
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• v.16 no.2
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• pp.69-78
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• 1988

For the modification of kiln drying schedule, rela ons between drying resistance R and moisture content or drying times were found 2.5cm-and 5.0cm-thick pitch pine (Pinus rigida Mill.) board and dimension lumber by the conventional kiln drying schedule until the average moisture content was 10%. The results of this study were as follows. 1. Drying resistance increased curvilinearly as moisture content decreased, and was higher for dimension lumber than for board at a given moisture content. The relationships between drying resistance and moisture content for the conventional kiln drying schedule and thickness of lumber were 1) $R_{2.5}=6.795\times10^3M^{-1.27^{**}}$ for 2.5cm-thick board by the conventional kiln drying schedule. 3) $R_{5.0}=5.206\times10^4M^{-1.55^{**}}$ for 5.0cm-thick dimension lumber by the conventional kiln drying schedule. 2. As drying time increased, moisture content decreased and drying resistance increased at the same time. Gradient of slope for dimension lumber was gentler than board. 3. The predicted drying times to 10% moisture content with the conventional kiln drying schedule were a little shorter than actual drying times with relatively small error. 4. It is necessary for the conventional kiln drying schedule to be modified to provide the desired final moisture content at minimum drying time with no significant degrade under severe drying conditions. 5. The kiln factors for 2.5cm-thick board and 5.0cm-thick dimension lumber with the conventional kiln drying schedule were 1.112, 1.136, respectively.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.133-137
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• 2017

The purpose of this study was to validate for GATE (Geant4 Application for Tomographic Emission) simulation by comparing the results of GATE simulation and experiment in real SPECT system. Futhermore, we want to prove that it is possible that the quantitative research of gamma camera/SPECT imaging for therapeutic radio isotope by using GATE simulation. In this study, the SPECT system on simulation referred to the parameters of Stream-R Forte version 1.2 (Philips Medical System, Best and Heerlen, Netherlands). To understand the I-131 image of gamma camera/SPECT system, we acquired the energy spectrum and measured the full width at half maximum (FWHM) which comes from line spread function (LSF) with and without scatter material in real SPECT system. And to compare with experiment, we also measured the FWHM and acquired the energy spectrum without scatter material in GATE simulation. As a result, without scatter material, the energy peak was almost same location, which are located nearby 364 keV, and other spectrum factors are same tendency in both cases. The FWHM was increased by increasing the distance of source to detector, and the error rate was approximately 3.8%. When we used the line source with scatter material, energy spectrum also indicated similar tendency in both cases. As you confirmed earlier, GATE simulation included real instrument and radioisotope characters for therapeutic radioisotope. Therefore this result that it was possible that various quantitative study for therapeutic radioisotope imaging in gamma camera/SPECT using GATE simulation.

• Korean Journal of Remote Sensing
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• v.36 no.5_2
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• pp.893-906
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• 2020

This paper reports on the analysis of the location accuracy of a precision image generation system manufactured for CAS 500. The planned launch date of the CAS 500 is 2021, and since it has not yet been launched, the analysis was performed using KOMPSAT-3A satellite images having similar specifications to the CAS 500. In this paper, we have checked the geolocation accuracy of initial sensor model, the model point geolocation accuracy of the precise sensor model, the geolocation accuracy of the precise sensor model using the check point, and the geolocation accuracy of the precise orthoimage using 30 images of the Korean Peninsula. In this study, the target geolocation accuracy is to have an RMSE within 2 pixels when an accurate ground control point is secured. As a result, it was confirmed that the geolocation accuracy of the precision sensor model using the checkpoint was about 1.85 pixels in South Korea and about 2.04 pixels in North Korea, and the geolocation accuracy of the precise orthoimage was about 1.15 m in South Korea and about 3.23 m in North Korea. Overall, it was confirmed that the accuracy of North Korea was low compared to that of South Korea, and this was confirmed to have affected the measured accuracy because the GCP (Ground Control Point) quality of the North Korea images was poor compared to that of South Korea. In addition, it was confirmed that the accuracy of the precision orthoimage was slightly lower than that of precision sensor medel, especially in North Korea. It was judged that this occurred from the error of the DTM (Digital Terrain Model) used for orthogonal correction. In addition to the causes suggested by this paper, additional studies should be conducted on factors that may affect the position accuracy.