• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.3
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• pp.455-463
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• 2015

This study investigated the effects of low-dose electron beam irradiation treatment on the physicochemical and sensorial properties of imported navel oranges during storage at $20^{\circ}C$ for 12 days. The samples were irradiated at doses of 0.2, 0.4, 0.6, 0.8, and 1.0 kGy, after which changes in color value, hardness, Brix/acid ratio, total sugar contents, reducing sugar contents, vitamin C contents, and sensory evaluation were investigated. There were no significant differences between non-irradiated and irradiated samples in terms of color value, Brix/acid ratio, total sugar contents, total reducing sugar contents, and vitamin C contents. Hardness of irradiated samples significantly decreased in the early storage period in an irradiation dose-independent manner, and the difference between non-irradiated and irradiated samples decreased again at the end of storage. For the sensory evaluation, there was no significant difference between non-irradiated and irradiated samples up to 0.6 kGy, and all sensory item scores decreased at the end of the storage period regardless of irradiation. These results suggest that electron beam irradiation below 0.6 kGy does not affect physicochemical and sensory properties during storage at $20^{\circ}C$. Thus, electron beam irradiation up to 0.6 kGy applied to imported navel oranges is the optimum dose for minimizing quality changes and disinfestation treatment.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.507-516
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• 2014

The present study was conducted to determine the effect of electron beam irradiation on control of Botrytis cinerea and postharvest quality of cut roses. Electron beam doses of 0.1, 0.2, 0.4, 0.6, 0.8, 1, 2, 10, and 20 kGy were applied with a 10-MeV linear electron beam accelerator (EB Tech, Korea). Electron beams inhibited spore germination and mycelial growth of B. cinerea with increasing irradiation doses. Conidia of B. cinerea were more tolerant to irradiation than were mycelia: the effective irradiation doses for 50% inhibition ($ED_{50}$) of spore germination and mycelial growth were 2.02 kGy and 0.89 kGy, respectively. In addition, electron beam irradiation was more effective in reducing mycelial growth of B. cinerea at $10^{\circ}C$ than at $20^{\circ}C$. Analysis of in vivo antifungal activity revealed that elevated irradiation doses exhibited increased control efficacy for tomato gray mold. Flower longevity and fresh weight of cut roses decreased when the irradiation dose was increased. In addition, flower bud opening tended to be inhibited in a dose-dependent manner. Although 'Decoration', 'Il se Bronze', 'Queen Bee', and 'Revue' roses tolerated and maintained overall postharvest quality up to 0.4 kGy, 'Vivian' did not, demonstrating that the irradiation sensitivity of cut roses varies according to cultivar.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.380-386
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• 2000

Electron beam (EB) was applied to study the sterilizing techniques for powdered red pepper and ginger by determining their quality over gamma radiation (GR) from the microbiological and organoleptic points of view. The samples showed high microbial loads, such as $10^5{\sim}10^6\;CFU/g$ in total aerobic bacteria, negligible levels in yeasts & molds and $10^2\;CFU/g$ in coliforms. EB irradiation at 5 kGy resulted in the reduction of microbial loads by 2 to 3 log cycles, thereby decreasing the levels of total bacteria to $10^2{\sim}10^3\;CFU/g$ and resulting in negative in coliforms. Decimal reduction doses $(D_{10})$ value on the initial bacterial loads in red pepper were $1.50{\sim}1.54\;kGy$ in EB and $1.68{\sim}1.80\;kGy$ in GR, while powdered ginger showed $1.30{\sim}2.27\;kGy$ in EB and $1.45{\sim}2.77\;kGy$ in GR, respectively. EB and GR showed a similar effect on microbial decontamination for both samples. Microbial populations in stored samples for 4 months at room temperature were not remarkably different from the initial loads in all samples. Irradiation caused little changes in Hunter's color parameters, but that were changable during storage. Sensory evaluations on color and odor of powdered samples indicated that no significant differences were observed among the all samples compared. These results revealed that EB irradiation at optimal dose levels for microbial control was not detrimental to the sensory quality of powdered red pepper and ginger.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.1
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• pp.128-136
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• 2015

This study investigated the effects of low-dose electron beam irradiation treatment on physicochemical and sensorial properties of imported navel oranges during storage at $3^{\circ}C$ for 45 days. The samples were irradiated at doses of 0.2, 0.4, 0.6, 0.8, and 1.0 kGy, and changes in their color values, hardness, Brix/acid ratio, total sugar contents, reducing sugar contents, vitamin C contents, and sensory evaluation were investigated. There were no significant differences between non-irradiated and irradiated samples in terms of color values, Brix/acid ratio, total sugar contents, total reducing sugar contents, and vitamin C contents. Hardness of irradiated sample at 1 kGy decreased significantly in the early storage period, but the difference between non-irradiated and irradiated samples decreased again at the end of storage. For the sensory evaluation, scores of color, sweetness, flavor, and overall acceptability decreased as irradiation dose and storage period increased. Samples irradiated at over 0.8 kGy showed low preference in all scores except color. These results suggest that electron beam irradiation below 0.6 kGy does not affect physicochemical and sensory properties; thus, electron beam irradiation up to 0.6 kGy in imported navel oranges is optimum for minimizing quality changes and disinfestation treatment simultaneously.

• The Journal of the Korean dental association
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• v.58 no.10
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• pp.604-614
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• 2020

Objective: The purpose of this study was to analyze the Cone-beam computed tomograghy(CBCT) scan of endodontically treated maxillary first molars and investigate how second mesiobuccal (MB2) canal is treated, how the prognosis of mesiobuccal (MB) root is different compared to other roots and the prognosis factor on apical periodontitis. Methods: Subjects were endodontically treated maxillary first molars whose were collected from CBCT scans taken from January 2018 until December 2019. A total of 525 maxillary first molars were analyzed by an endodontist to determine the presence of the MB2 canal, the quality of the root canal filling, and the presence of apical periodontitis. The chi square test and Fisher's exact test was used to examine the relationship between each variable. Results: MB2 canals were found in 46.3%, of which 76.5% were not treated. The more main canal of mesiobuccal root (MB1 canal) was well filled, the more significantly MB2 canal was well filled (p<0.001). The apical periodontitis of MB root was not related to the filling quality of MB1 canal (p=0.370) and was related to the filling quality of MB2 canal (p=0.004). The apical periodontitis of MB root was related to the quality of canal filling of MB2 canal and the apical periodontitis of DB and P root. Conclusions: It was found that the majority of MB2 canals were not treated. The apical periodontitis of MB root was analyzed to be related to the quality of canal filling of MB2 canal. The apical lesion of the MB root was not correlated with the treatment of the MB1 canal, but it was significantly related to the quality of filling of MB2 canal.

• Progress in Medical Physics
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• v.32 no.4
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• pp.107-115
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• 2021

Purpose: The purpose of this study was to compare the clinical quality assurance results of portal dosimetry using an electronic portal imaging device, a method that is extensively used for patient-specific quality assurance, and the newly released Mobius3D for intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). Methods: This retrospective study includes data from 122 patients who underwent IMRT and VMAT on the Novalis Tx and VitalBeam linear accelerators between April and June 2020. We used a paired t-test to compare portal dosimetry using an electronic portal imaging device and the average gamma passing rates of MobiusFX using log files regenerated after patient treatment. Results: The average gamma passing rates of portal dosimetry (3%/3 mm) and MobiusFX (5%/3 mm) were 99.43%±1.02% and 99.32%±1.87% in VitalBeam and 97.53%±3.34% and 96.45%±13.94% in Novalis Tx, respectively. Comparison of the gamma passing rate results of portal dosimetry (3%/3 mm) and MobiusFX (5%/3 mm as per the manufacturer's manual) does not show any statistically significant difference. Conclusions: Log file-based patient-specific quality assurance, including independent dose calculation, can be appropriately used in clinical practice as a second-check dosimetry, and it is considered comparable with primary quality assurance such as portal dosimetry.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.94-100
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• 2011

Purpose: Basal/Acetazolamide-challenged brain perfusion SPECT is very useful to assess cerebral perfusion and vascular reserve. However, as there is a trade off between sensitivity and spatial resolution in the selection of collimator, the selection of optimal collimator is crucial. In this study, we examined three collimators to select optimal one for 1-day brain perfusion SPECT. Materials and Methods: Three collimators, low energy high resolution-parallel beam (LEHR-par), ultra resolution-fan beam (LEUR-fan) and super fine-fan beam (LESFR-fan), were tested for 1-day imaging using Triad XLT 9 (TRIONIX). The SPECT images of Hoffman 3D brain phantom filled with 99mTc of 170 MBq and a normal volunteer were acquired with a protocol of 50 kcts/frame and detector rotation of 3 degree. Filterd backprojection (FBP) reconstruction with Butterworth filter (cut off frequencies, 0.3 to 0.5) was performed. The quantitative and qualitative assessments for three collimators were performed. Results: The blind tests showed that LESFR-fan provided the best image quality for Hoffman brain phantom and the volunteer. However, images for all the collimator were evaluated as 'acceptable'. On the other hand, in order to meet the equivalent signal-to-noise ratio (SNR), total acquisition time or radioactivity dose for LESFR-fan must have been increased up to almost twice of that for LEUR-fan and LEHR-par. The volunteer test indicated that total acquisition time could be reduced approximately by 10 to 14 min in clinical practice using LEUR-fan and LEHR-par without significant loss on image quality, in comparison with LESFR-fan. Conclusion: Although LESFR-fan provides the best image quality, it requires significantly more acquisition time than LEUR-fan and LEHR-par to provide reasonable SNR. Since there is no significant clinical difference between three collimators, LEUR-fan and LEHR-par can be recommended as optimal collimators for 1-day brain perfusion imaging with respect to image quality and SNR.

• The Journal of Korean Society for Radiation Therapy
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• v.34
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• pp.13-20
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• 2022

Purpose : IMRT using Tomotherapy during nasopharyngeal cancer radiation therapy irradiate an accurate dose to tumor tissues and is effective to reduce a dose rapidly in normal tissues. However, this has high MU and long Beam On Time. This study aims to analyze differences in tumors, normal tissues and low-dose distributions and the efficiency of Split VMAT after applying Helical IMRT (Tomotherapy), VMAT (Linac : 2Arc) and Split VMAT (Linac : 4Arc) plans. Materials and Methods : This study targeted ten nasopharyngeal cancer patients of this hospital and compared three treatment plans (Helical IMRT, VMAT, Split VMAT). For Helical IMRT planning, Precision^® (Version 1.1.1.1, Accuray, USA) was used, and for VMAT and Split VMAT planning, Pinnacle^3® (Version 9.10, Philips, USA) was used. The total dose applied was 38.4 Gy / 32 Gy (Daily Dose 2.4 Gy (GTV + 0.3 cm) / 2 Gy (CTV + 0.3 cm) 16Fx), and for GTV + 0.3 cm (P_GTV), 95% of V_38.4Gy was prescribed. VMAT with an angle of 360° 2Arc was applied, and for Split VMAT, the field was divided into the right, the left, the top and the bottom and an angle of 360° 4Arc, 6MV was set. For evaluating the quality of the treatment plans, differences in tumors, normal tissues and low-dose area were compared, and Beam On Time was measured to analyze the efficiency. Results : When calculating the mean values of evaluation items of the three treatment plans (Helical IMRT, VMAT, Split VMAT) for the patients, the H.I (Homogeneity Index) of P_GTV was 1.04, 1.11 and 1.1 respectively, and the C.I (Confomity Index) of P_CTV was 1.03, 0.99 and 1.00 respectively. The mean dose of RT Parotid Gland (Gy) was 14.54, 17.06 and 14.76 respectively, the mean dose of LT Parotid Gland (Gy) was 14.32, 17.32 and 15.09 respectively, the maximum dose of P_Cord (Spinal Cord + 0.3 cm) (Gy) was 20.57, 22.59 and 21.06 respectively, and the maximum dose of Brain Stem (Gy) was 22.35, 23.99 and 21.68 respectively. The 50% isodose curve (cc) was 1332, 1132.5 and 1065.2 respectively. Beam On Time (sec) was 373.7, 130.7 and 254.4 respectively. Conclusion : Displaying a similar treatment plan quality to Helical IMRT, which is used a lot for head and neck treatment, Split VMAT reduced the low-dose area and Beam On Time and produced a better result than VMAT. Therefore, it is considered that Split VMAT is effective not only for nasopharyngeal cancer but also for other head and neck cancers.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.190-196
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• 2004

ACR(All Clear Reflector), also widely referred to as FFR(Free Form Reflector), were designed in general and intelligent ways using a NUDBS surface for the mathematical modelling of the reflector shape and artificial intelligence as the optimum design algorithm. An ACR, which consists of a continuous surface reflector and clear outer lens, offers styling advantages and provides a high quality light performance. The clear outer lens of an ACR remains efficient even with a highly inclined shape, as in the design of a sports car, as well as the complete clearness of the reflector surface eliminates the nuisance of stray light caused by the steps between adjacent segments of multi-faced reflectors. The application of an ACR to low beam lamp was so sucessful to obtain the sharp cut-off with the lens-free single-surfaced-smooth reflector. The design technique of ACR was tested with all types of lamps, including low beams, high beams, and fog lamps.

• The Journal of the Acoustical Society of Korea
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• v.39 no.3
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• pp.200-206
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• 2020

In this paper, we propose a broadband beamforming method using the Spatial Response Variation (SRV) which is defined to measure the fluctuation of the array spatial response within the desired frequency band. By applying the SRV to regularization term, we achieve a good quality main beam width variation less than 1 degree within the desired frequency band. In design experiments, we show that the proposed method is better than the existing method.