• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.77-84
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• 2017

Purpose: To evaluate the image quality improvement and dosimetric effects on virtual monochromatic images of a Dual Source-Dual Energy CT(DS-DECT) for radiotherapy planning. Materials and Methods: Dual energy(80/Sn 140 kVp) and single energy(120 kVp) scans were obtained with dual source CT scanner. Virtual monochromatic images were reconstructed at 40-140 keV for the catphan phantom study. The solid water-equivalent phantom for dosimetry performs an analytical calculation, which is implemented in TPS, of a 10 MV, $10{\times}10cm^2$ photon beam incident into the solid phantom with the existence of stainless steel. The dose profiles along the central axis at depths were discussed. The dosimetric consequences in computed treatment plans were evaluated based on polychromatic images at 120 kVp. Results: The magnitude of differences was large at lower monochromatic energy levels. The measurements at over 70 keV shows stable HU for polystyrene, acrylic. For CT to ED conversion curve, the shape of the curve at 120 kVp was close to that at 80 keV. 105 keV virtual monochromatic images were more successful than other energies at reducing streak artifacts, which some residual artifacts remained in the corrected image. The dose-calculation variations in radiotherapy treatment planning do not exceed ${\pm}0.7%$. Conclusion: Radiation doses with dual energy CT imaging can be lower than those with single energy CT imaging. The virtual monochromatic images were useful for the revision of CT number, which can be improved for target coverage and electron densities distribution.

• Journal of Korean Society of Transportation
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• v.24 no.5 s.91
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• pp.35-44
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• 2006

Acceleration and deceleration curves have been used for design purposes worldwide. The curve in design level has been regarded as an single deterministic curve to be used for design of climb lanes. It should be noted that the curve was originally made using ideal driving truck and that the curve is applied during design based on the assumption of no difference between ideal and real driving conditions. However. observations show that aged vehicles and lazy behavioring drivers nay make lower performance of vehicles than the ideal performance. The present paper provides the results of truck speeds at climbing lanes then probabilistic variation of acceleration and deceleration corves. For these purposes. a study about identification of vehicle makers, and weights for trucks at freeway toll gates and then observation of vehicle-following speed were performed. The 85%ile results obtained were compared with the deterministic performance curves of 180, 200, and 220 Ib/hp. It was identified that the performance of 85%ile results obtained from vehicle-following-speed observations were lower than one from deterministic performance curves. From these results, it may be concluded that at the beginning Point of climbing lanes additional $16.19{\sim}67.94m$ is necessary and that at the end point of climbing lanes $53.12{\sim}103.24m$ of extension is necessary.

• Radiation Oncology Journal
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• v.20 no.3
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• pp.283-293
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• 2002

Purpose : A PC based brachytherapy planning system was developed to display dose distributions on simulation images by 2D isodose curve including the dose profiles, dose-volume histogram and 30 dose distributions. Materials and Methods : Brachytherapy dose planning software was developed especially for the Ir-192 source, which had been developed by KAERI as a substitute for the Co-60 source. The dose computation was achieved by searching for a pre-computed dose matrix which was tabulated as a function of radial and axial distance from a source. In the computation process, the effects of the tissue scattering correction factor and anisotropic dose distributions were included. The computed dose distributions were displayed in 2D film image including the profile dose, 3D isodose curves with wire frame forms and dosevolume histogram. Results : The brachytherapy dose plan was initiated by obtaining source positions on the principal plane of the source axis. The dose distributions in tissue were computed on a $200\times200\;(mm^2)$ plane on which the source axis was located at the center of the plane. The point doses along the longitudinal axis of the source were $4.5\~9.0\%$ smaller than those on the radial axis of the plane, due to the anisotropy created by the cylindrical shape of the source. When compared to manual calculation, the point doses showed $1\~5\%$ discrepancies from the benchmarking plan. The 2D dose distributions of different planes were matched to the same administered isodose level in order to analyze the shape of the optimized dose level. The accumulated dose-volume histogram, displayed as a function of the percentage volume of administered minimum dose level, was used to guide the volume analysis. Conclusion : This study evaluated the developed computerized dose planning system of brachytherapy. The dose distribution was displayed on the coronal, sagittal and axial planes with the dose histogram. The accumulated DVH and 3D dose distributions provided by the developed system may be useful tools for dose analysis in comparison with orthogonal dose planning.

• Journal of Preventive Medicine and Public Health
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• v.28 no.4 s.51
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• pp.899-910
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• 1995

This study was conducted to determine the correlation between weighted needle pinprick sensory threshold(PPT) and sensory nerve conduction tests. The subjects were 53 healthy controls, 31 diabetic patients without peripheral neuropathic symptoms(DM) and 36 diabetic patients with peripheral neuropathic symptoms(DN). PPT was measured on the index and little fingers, bilaterally, as well as under the lateral malleolus, bilaterally. In electrophysiologic assessment the left and right median, ulnar and sural nerves were studied. Each mean PPTs was high in order of controls, DM and DN. Age adjusted PPT was significantly different among three groups on right little finger(p<0.05) and left malleolus(p<0.05), but not significantly different between DN and DM on other sites. Each sensory nerve conduction velocity and amplitude was statistically significantly different among three groups(p<0.05). Correlations of PPT with sensory nerve conduction velocity and amplitude were statistically significant on each site and ranged from -0.4203(left malleolus) to -0.5649(right index finger) and from -0.3897(left index finger) to -0.6200(right index finger), respectively. When electrophysiological study is not feasible, measurement of PPT may be helpful for the assessment of peripheral sensory neurological function.

• Journal of Preventive Medicine and Public Health
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• v.29 no.4 s.55
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• pp.801-814
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• 1996

Background: Korean people could abuse healthy foods as well as medications, which might cause serious side effects. The aim of this study was elucidating liver dysfunction due to the self-medications of hepatotonics, healthy foods and herb medications by nested case-control study. Methods: Study subjects were drawn from male members of Seoul Cohort Study who were recruited by self-administered structured questionnaire survey through mailing to the healthy men between the age of 40 and 59 years through the program of biennial health check-up offered by Korea Medical Insurance Corporation(KMIC). The liver dysfunction was defined as the level of serum AST and ALT above 40 IU/L and increased in more than one hunderd per-cent during the 2 year follow-up period. To estimate the odds ratio between self-medication and liver dysfunction after controlling for potential confounders, logistic regression was performed. Results: During the follow-up period, 30 members were identified to fit into case criteria and 2,625 members were selected as control. In logistic regression analyses, history of healthy foods intake, age under 45 years, obesity, and habit of regular exercise were significantly associated with liver dysfunction. The following factors exhibited no statistical significance: intake of hepatotonics, of herb medicine; history of disease in family, of operation, and of radiologic examination; smoking habits and drinking amounts. Conclusion: The significant association between the intake of healthy foods and the liver dysfunction illustrates that chronically optional overuse of healthy foods might bring to hazards to health. As the increasing trend of the size of purchasing healthy foods in Korea, pharmacoepidemiologic studies evaluating the safety and efficacy of the widely used healthy foods should be performed in the near future.

• The Korean Journal of Nuclear Medicine
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• v.36 no.4
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• pp.271-276
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• 2002

Purpose: To measure reliable glomerular filtration rate by using the representative values of transplanted renal depths, which are measured with ultrasonography. Materials and Methods: We included 54 patients (26 men, 28 women), with having both renal scintigraphy and ultrasonography after renal transplantation. We measured GFR with Gates' method using the renal depth measured by ultrasonography, and median and mean ones in each patient. We compared GFR derived from ultrasonography-measured renal depth with GFR derived from median and mean renal depths. The correlation coefficients were obtained among GFR derived from ultrasonography-measured renal depths, median and mean renal depths under linear regression analysis. We determined whether GFR derived from median or mean renal depth could substitute GFR derived from ultrasonography-measured renal depth with Bland-Altman method. We analyze the expected errors of the GFR using representative renal depth in terms of age, sex, weight, height, creatinine value, and body surface. Results: The transplanted renal depths range from 3.20 cm to 5.96 cm. The mean value and standard deviation of renal depths measured by ultrasonography are $4.09{\pm}0.65cm$ in men, and $4.24{\pm}0.78cm$ in women. The median value of renal depths measured by ultrasonography is 4.36 cm in men and 4.14 cm in women. The GFR derived from median renal depth is more consistent with GFR derived from ultrasonography-measured renal depth than GFR derived from mean renal depth. Differences of GFR derived from median and ultrasonography-measured renal depth are not significantly different in the groups classified with creatinine value, age, sex, height, weight and body surface. Conclusion: When median value is adapted as a representative renal depth, we could obtain reliable GFR in transplanted kidney simply.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.23 no.1
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• pp.1-19
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• 2018

In order to compare significant wave height (SWH) data from multi-satellites (GFO, Jason-1, Envisat, Jason-2, Cryosat-2, SARAL) and SWH measurements from Ieodo Ocean Research Station (IORS), we constructed a 12 year matchup database between satellite and IORS measurements from December 2004 to May 2016. The satellite SWH showed a root mean square error (RMSE) of about 0.34 m and a positive bias of 0.17 m with respect to the IORS wave height. The satellite data and IORS wave height data did not show any specific seasonal variations or interannual variability, which confirmed the consistency of satellite data. The effect of the wind field on the difference of the SWH data between satellite and IORS was investigated. As a result, a similar result was observed in which a positive biases of about 0.17 m occurred on all satellites. In order to understand the effects of topography and the influence of the construction structures of IORS on the SWH differences, we investigated the directional dependency of differences of wave height, however, no statistically significant characteristics of the differences were revealed. As a result of analyzing the characteristics of the error as a function of the distance between the satellite and the IORS, the biases are almost constant about 0.14 m regardless of the distance. By contrast, the amplitude of the SWH differences, the maximum value minus the minimum value at a given distance range, was found to increase linearly as the distance was increased. On the other hand, as a result of the accuracy evaluation of the satellite SWH from the Donghae marine meteorological buoy of Korea Meteorological Administration, the satellite SWH presented a relatively small RMSE of about 0.27 m and no specific characteristics of bias such as the validation results at IORS. In this paper, we propose a conversion formula to correct the significant wave data of IORS with the satellite SWH data. In addition, this study emphasizes that the reliability of data should be prioritized to be extensively utilized and presents specific methods and strategies in order to upgrade the IORS as an international world-wide marine observation site.

• Journal of Hospice and Palliative Care
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• v.17 no.1
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• pp.27-33
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• 2014

Purpose: Although vitamin D deficiency is more commonly found in cancer patient than in non-cancer patients, there have been little data regarding the prevalence of vitamin D deficiency in cancer patients at the very end of life. We examined vitamin D deficiency in terminally ill cancer patients and related factors. Methods: This study was based on a retrospective chart review of 133 patients in a hospice ward. We collected data regarding age, sex, serum 25-hydroxyvitamin D level, cancer type, physical performance, current medications and various laboratory findings. We investigated factors related to serum vitamin D levels after multivariate adjustment for potential confounders. Serum 25-hydroxyvitamin D<20 ng/mL was considered deficient and <10 ng/mL severely deficient. Results: Ninety-five percent of the patients were serum vitamin D deficient. Severe vitamin D deficiency was more common in male patients, non-lung cancer patients, $H_2$ blocker users and non-anticonvulsant users. Elevated levels of serum alanine aminotransferase (ALT) were also associated with low serum vitamin D levels. Multiple regression analysis showed that severe vitamin D deficiency was associated with male gender (aOR 3.82, 95% CI: 1.50~9.72, P=0.005), $H_2$ blocker users (aOR 3.94, 95% CI: 1.61~9.65, P=0.003) and elevated serum ALT levels (aOR 4.52, 95% CI: 1.35~15.19, P=0.015). Conclusion: Vitamin D deficiency was highly prevalent among terminally ill cancer patients. Severe vitamin D deficiency was more common in male patients, $H_2$ blocker users, and patients with elevated ALT levels.

• Korean Journal of Breeding Science
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• v.41 no.3
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• pp.220-227
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• 2009

This study was conducted to select superior families based on the open-pollinated (OP) progeny tests of P. densiflora. A total of 232 OP families were analyzed for relative height growth. The OP progeny test trials were established at 1 to 4 sites from 1975 to 1987. To minimize temporal and spatial variation, we applied the standardization method for family selection. In each progeny test, superior and inferior families were selected at ages of 10, 20 and 30. Relative height growth rate (RHGR), growth speed at a given time unit, was comparatively high at age of 10 with range from 0.1 to 0.6 and showed a large variation among families. However, after age 15, the RHGR was low (average 0.04) and also the variation was not significantly different among families. To reduce selection errors due to age differences (from age 23 to 35) of tests, we made the family selection after age 15 when the values of RHGR were stable. Height growth at each age was transformed to be height growth at age 35 based on the RHGR. As the results, family CB2, CB3, KW99 and KW2 were selected as superior families and KW158, KW22, KB40 and GG1 were considered as inferior ones, respectively. Rank correlations (r) between test ages and selection age 35 were high and statistically significant; r = 0.881 between age 30 and 35, 0.653 between age 20 and 35, and -0.222 between age 10 and 35.

• Korean Journal of Remote Sensing
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• v.12 no.2
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• pp.139-154
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• 1996

In order to evaluate the sensor`s look direction bias in the Landsat TM image and to estimate trends of primary geological lineaments, we have attempted to systematically compare lineaments in TM image, relief shadowed DEM's, and actual lineaments of geologic and topographic map through the Hough transform technique. Hough transform is known to be very effective to estimate the trend of geological lineaments, and help us to obtain the true trends of lineaments. It is often necessary to compensate the preferential enhancements of terrain lineaments in a TM image occurred by to look direction bias, and that can be achieved by utilizing an auxiliary data. In this study, we have successfully adopted the relief shadowed DEM in which the illuminating azimuth angle is perpendicular to look direction of a TM image for assessing true trends of geological lineaments. The results also show that the sum of four relief shadowed DEM's directional components can possibly be used as an alternative. In Euiseong-gun area where Sindong Group and Mayans Group are mainly distributed, geological lineaments trending $N5^{\circ}$~$10^{\circ}$W are dominant, while those of $N55^{\circ}$~$65^{\circ}$ W are major trends in Cheongsong-gun area where Hayang Group, Yucheon Group and Bulguksa Granite are distributed. Using relief shadowed DEM as an auxiliary data, we found the $N55^{\circ}$~$65^{\circ}$ W lineaments which are not cleanly observed in TM image over Euiseong-gun area. Compared with the trend of Gumchon and Gaum strike-slip faults, these lineaments are considered to be an extension of the faults. Therefore these strike-slip faults possibly extend up to Sindong Group in the northwest parts in the study area.