• The Journal of Information Systems
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• v.29 no.3
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• pp.145-157
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• 2020

Purpose This study proposed an approach for predicting the efficiency rating of the cultural tourism festivals using DEA and machine learning techniques. The cultural tourism festivals are selected for the best festivals through peer reviews by tourism experts. However, only 10% of the festivals which are held in a year could be evaluated in the view of effectiveness without considering the efficiency of festivals. Design/methodology/approach Efficiency scores were derived from the results of DEA for the prediction of efficiency ratings. This study utilized BCC models to reflect the size effect of festivals and classified the festivals into four ratings according the efficiency scores. Multi-classification method were considered to build the prediction of four ratings for the festivals in this study. We utilized neural networks and SVMs with OAO(one-against-one), OAR(one-against-rest), C&S(crammer & singer) with Korea festival data from 2013 to 2018. Findings The number of total visitors in low efficient rating of DEA is more larger than the number of total visitors in high efficient ratings although the total expenditure of visitors is the highest in the most efficient rating when we analyzed the results of DEA for the characteristics of four ratings. SVM with OAO model showed the most superior performance in accuracy as SVM with OAR model was not trained well because of the imbalanced distribution between efficient rating and the other ratings. Our approach could predict the efficiency of festivals which were not included in the review process of culture tourism festivals without rebuilding DEA models each time. This enables us to manage the festivals efficiently with the proposed machine learning models.

• The Journal of Korean Society of Virology
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• v.27 no.2
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• pp.197-207
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• 1997

To investigate the NS4 region of JEV, NS4 cDNA of K94P05 (JEV strain isolated from Korea in 1994) was amplified by RT-PCR and analyzed by sequencing PCR product. Genomic size of NS4 was 1212bp and nucleotide sequence was compared with that of other JEV strains. Nucleotide homology between JaOAr582 and K94P05 was 91.1% and that between Beijing and K94P05 was 89.8%, respectively. But the nucleotide sequence of E region of JaOAr582 and K94P05 showed 97.0% homology and that of Beijing and K94P05 did 95.8% homology. NS4 protein was expressed as a form of fusion protein by a prokaryotic expression system. The induced fusion product showed a lower molecular weight than predicted size and remained insoluble. The NS4 protein might be cleavaged by E. coli protease. Concluding above results, high hydrophobicity of the NS4 protein supported the fact that this protein played a role as a membrane component and the poor nucleotide sequence conservativity among JEV strains suggested that this region might be important to adapt each viral growth environment.

• Radiation Oncology Journal
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• v.30 no.1
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• pp.27-35
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• 2012

Purpose: To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients. Materials and Methods: Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose. Results: Regardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The $V_{20Gy}$ of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%. Conclusion: In this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.

• Progress in Medical Physics
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• v.24 no.4
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• pp.284-289
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• 2013

A study was performed comparing dosimetric characteristics of volumetric modulated arc and intensity modulated radiatio therapy on patients with bilateral breast cancer. For 5 patients, 3 plans were made for each patient; IMRT beams 8 and 12 of the beam intensity modulated radiation therapy, volumetric modulated arc therapy plan. The average PTVs volumes and $D_{98}$ for 12-IMRT were $51.04{\pm}0.57$ Gy (right), $50.80{\pm}1.07$ Gy (left), $42.94{\pm}16.16$ Gy (right), $42.56{\pm}2.09$ Gy (left). HI ($D_5{\sim}D_{95}$) and $CI_{90,95}$, even 12-IMRT has shown excellent results. In OAR, 3 plans showed excellent results. But the lowest dose of 12-IMRT. 12-IMRT achieved similar PTV coverage and sparing of organs at risk than 8-IMRT and VMAT.

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.917-920
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• 2007

Ketene-forming eliminations from C4H3(S)CH2C(O)O-C6H3-2-X-4-NO2 (1) promoted by R2NH in MeCN have been studied kinetically. The reactions are second-order and exhibit Bronsted β =0.51-0.62 and |βlg|= 0.47-0.53. Hence, an E2 mechanism is evident. The Bronsted β increased from 0.33 to 0.53 and |βlg| remained nearly the same by the change of the base-solvent from Bz(i-Pr)NH/Bz(i-Pr)NH2+ in 70 mol% MeCN(aq) to Bz(i-Pr)NH-MeCN, indicating a change to a more symmetrical transition state with similar extents of Cβ -H and Cα -OAr bond cleavage. When the β-aryl group was changed from thienyl to phenyl in MeCN, the β value increased from 0.53 to 0.73 and |βlg| decreased from 0.53 to 0.43. This indicates that the transition state became skewed toward more Cβ -H bond breaking with less Cα-OAr bond cleavage. Noteworthy is the greater double bond stabilizing ability of the thienyl group in the ketene-forming transition state.

• Journal of radiological science and technology
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• v.46 no.3
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• pp.239-246
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• 2023

In this study, we assessed the effect of reduction of tumor volume in the head and neck cancer by using RANDO phantom in Static Intensity-Modulated Radiation Therapy (S-IMRT) and Volumetric-Modulated Arc Therapy (VMAT) planning. RANDO phantom's body and protruding volumes were delineated by using Contour menu of Eclipse™ (Varian Medical System, Inc., Version 15.6, USA) treatment planning system. Inner margins of 2 mm to 10 mm from protruding volumes of the reference were applied to generate the parameters of reduced volume. In addition, target volume and Organ at Risk (OAR) volumes were delineated. S-IMRT plan and VMAT plan were designed in reference. These plans were assigned in the reduced volumes and dose was calculated in reduced volumes using preset Monitor unit (MU). Dose Volume Histogram (DVH) was generated to evaluate treatment planning. Conformity Index (CI) and R² in reference S-IMRT were 0.983 and 0.015, respectively. There was no significant relationship between CI and the reduced volume. Homogeneity Index (HI) and R² were 0.092 and 0.960, respectively. The HI increased when volume reduced. In reference VMAT, CI and R² were 0.992 and 0.259, respectively. There was no relationship between the volume reduction and CI. On the other hand, HI and R² were 0.078 and 0.895, respectively. The value of HI increased when the volume reduced. There was significant difference (p<0.05) between parameters (D_mean and D_max) of normal organs of S-IMRT and VMAT except brain stem. Volume reduction affected the CI, HI and OAR dose. In the future, additional studies are necessary to incorporate the reduction of the volume in the clinical setting.

• Progress in Medical Physics
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• v.33 no.4
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• pp.101-107
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• 2022

Purpose: Radiotherapy after bladder filling protocol (BFP) is known to enhance treatment quality and reduce side effects in prostate cancer, a common male solid cancer globally. However, due to the need to hold back urine during treatment, patients frequently complain of discomfort, and treatment is frequently suspended when patients urinate during treatment and urine penetrates the treatment device, causing malfunction. Therefore, the effect of minimizing treatment time when partial-arc volumetric modulated arc therapy (VMAT) was used instead of full-arc was assessed in this study. Methods: A total of 70 plans were created in 10 patients using 7 different arc sizes, and the treatment time for each plan was calculated. Results: Reduced arc size by half resulted in a 54.4% decrease in mean treatment duration, with a proportional tendency observed. Furthermore, the effect of VMAT arc size reduction on target dose homogeneity was significantly limited, and the effect on surrounding organs at risk (OAR) was negligible. It should be noted, however, that when the arc size decreases by >40%, the dose increases in the area without OAR around the target. Conclusions: The results of this study demonstrated that partial-arc VMAT for enhancing treatment convenience and efficacy of prostate cancer patients undergoing BFP can achieve a considerable reduction in treatment time while preserving treatment quality, and it is expected to be useful for partial-arc VMAT plan design and implementation in practice.

• Progress in Medical Physics
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• v.27 no.1
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• pp.14-24
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• 2016

Since the head and neck region is densely located with organs at risk (OAR), OAR-sparing is an important issue in the treatment of head and neck cancers. This study-in which different treatment plans were performed varying the head tilt angle on brain tumor patients-investigates the optimal head elevation angle for sparing normal organs (e.g. the hippocampus) and further compares the dosimetric characteristics of different types of radiation equipment. we performed 3D conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and tomotherapy on 10 patients with brain tumors in the frontal lobe while varying the head tilt angle of patients to analyze the dosimetric characteristics of different therapy methods. In each treatment plan, 95% of the tumor volume was irradiated with a dose of 40 Gy in 10 fractions. The step and shoot technique with nine beams was used for IMRT, and the same prescription dose was delivered to the tumor volume for the 3D-CRT and tomotherapy plans. The homogeneity index, conformity index, and normal tissue complication probability (NTCP) were calculated. At a head elevation angle of $30^{\circ}$, conformity of the isodose curve to the target increased on average by 53%, 8%, and 5.4%. In 3D-CRT, the maximum dose received by the brain stem decreased at $15^{\circ}$, $30^{\circ}$, and $40^{\circ}$, compared to that observed at $0^{\circ}$. The NTCP value of the hippocampus observed in each modality was the highest at a head and neck angle of $0^{\circ}$ and the lowest at $30^{\circ}$. This study demonstrates that the elevation of the patients' head tilt angle in radiation therapy improves the target region's homogeneity of dose distribution by increasing the tumor control rate and conformity of the isodose curve to the target. Moreover, the study shows that the elevation of the head tilt angle lowers the NTCP by separating the tumor volume from the normal tissues, which helps spare OARs and reduce the delivered dose to the hippocampus.

• Journal of Radiation Protection and Research
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• v.39 no.4
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• pp.168-175
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• 2014

This study was designed to assess whether the conventional tangential technique, using a multileaf collimator (MLC), allows a reduced dose to the organs at risk (OAR) in breast radiation therapy. A total of forty right and left 20 for each breast cancer patients that underwent radiation therapy after breast conserving surgery were included in this study. For each patient, the planning target volume (PTV) and OAR (heart, left anterior descending artery (LAD), liver and lung) were defined and dose distribution were produced for conventional tangential beams using 6 MV photons. The treatment plans were made using the following two techniques for all patients. For the first plan (P1), MLC was designed to shield as much of OAR as possible without compromising the coverage of PTV. In the second plan (P2), the treatment plan was created without using MLC. Dose-volume histograms for OARs were calculated for all plans. For left breast cancer, the percentage of maximum dose ($D_{max%}$) and mean dose ($D_{mean%}$) of OARs (heart and LAD) were calculated, and for right breast cancer, the percentage of the mean dose ($D_{mean%}$) of the liver was calculated. The $D_{mean%}$ of the lung was calculated in all patients. The mean values of $D_{max%}$ of the heart ($86.9{\pm}19.5%$ range, 35.1-100.6%) in P1 were significantly lower than in P2 ($98.3{\pm}3.4%$ range, 91.7-105.2%) (p=0.001). The mean values of $D_{max%}$ of LAD ($78.4{\pm}22.5%$ range, 26.5-99.7%) in P1 was significantly lower than in P2 ($93.3{\pm}8.1%$ range, 67.9-102.1%) (p<0.001). In P1, the mean values of $D_{mean%}$ of the liver ($4.8{\pm}2.0%$) were significantly lower than in P2 ($6.2{\pm}2.5%$) (p<0.001). The mean values of $D_{mean%}$ of the lung were significantly lower in P1 ($9.3{\pm}2.3%$) than in P2 ($9.7{\pm}2.4%$) (p<0.001). P1, by using MLC, allows a significantly reduced dose to OAR compared with P2. We can suggest that it is reasonable to routinely use MLC in the conventional tangential technique for breast radiation therapy considering the primary tumor location.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.73-81
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• 2018

Purpose : The aims of this study were to compare and assess the effectiveness of Volumetric Modulated Arc Therapy(VMAT) using jaw tracking(JT) and fixed jaw(FJ) in radiation therapy of multiple brain metastasis. Methode and material : Among the patients with Multiple Brain Metastasis treated with jaw tracking, 10 patients with more than 6 tumors and with the size of radiation field $14{\times}14cm^2$ or more were included. Each Treatment plans with jaw tracking(JT) and fixed jaw(FJ) was established with Eclipse (Ver. 13.6 Varian, USA). Gamma Index (3 mm, 3 % confidence interval - 95 %) and maximum dose difference were measured with an electronic portal imaging device(EPID). The $D_{max}$ and $D_{mean}$ of Organ At Risk(OAR) were assessed and compared, and the Conformity Index(CI) and Homogeneity Index(HI) were evaluated. Result : Evaluating jaw tracking(JT) and fixed jaw(FJ) outcomes, in all cases, Gamma Index met the permissible standard of 3 mm, 3 % confidence intervals of 95 %. The maximum dose difference value from the areas with leaf end transmission was measured at a maximum of 98.4 % and an average of 43.6 % in clockwise(CW), and 67.9 % and 41.0 % for each in Counter-Clockwise(CCW). With jaw tracking, the maximum value of $D_{max}$ for each normal organ in OAR decreased in 15.36 %~74.59 % with the average value decreasing in 2.84 %~39.80 %. The maximum value of $D_{mean}$ in OAR decreased in 27.90 %~65.23 %, with the average value decreasing in 7.70 %~41.71 %. No change has been found in Conformity Index and Homogeneity Index values. Conclusion : When Jaw tracking is used in treating patients with multiple brain metastasis with VMAT, the unnecessary exposure due to leakage and transmission of radiation in unspecified areas was reduced, without affecting the dose distribution of the planning target volume(PTV), and the availability of radiation therapy with lower doses in normal organs is expected.