• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.351-357
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• 2019

This research was performed to propose domestic standard for design and management of flexible hose by analyzing chlorine leak caused by breakage of the hose in Ulsan, 2018. The leak had multiple causes but this paper focuses on analyzing the cause of breakage of flexible hose, the direct cause. According to the analysis, flexible hose that the company of the accident used for chlorine transfer was inappropriate in several aspects including material and wall thickness. And even pressure test had been conducted below operating pressure. Upon investigation on five companies that handle chlorine in Ulsan, four companies were using inappropriate flexible hose for chlorine transfer. Since there is no domestic standard for the design of flexible hose for chlorine transfer at present, it is hard to examine its design adequacy. Design standard of flexible hose used in chlorine transfer that is applicable domestically is proposed based on this research. It will contribute to the reduction in risk of breakage of the hose if the proposed standard could be applied in design and examination of flexible hose.

• Computational Structural Engineering
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• v.9 no.2
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• pp.143-151
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• 1996

The optimal design for Electro-magnetic Launcher (EML : Rail Gun) considering structural and electrical constraints are presented. For the structure of EML under high pulsed currency, the cross section is minimized subject to maximum stress of each element(rail, side wall, ceramic, and steel) within allowable stress and preload limits. The electrical constraint is the effective ceramic thickness which prevents the eddy current effect reducing the performance of EML. The stress analysis and optimization procedure of 90mm EML is conducted with ANSYS Code. The optimal design under preload is reduced to 53% of area compared with optimal design without preload. In case of rail with arc angle .theta.=45.deg., the performance of EML is the best among the other rail arc angles. The optimal design for rail with arc angle .theta.=45.deg., results in the reduction of 9% of area and 10.4% of deformation compared with Fahrenthold's design. The optimal preload 59.8MPa is much lower than Fahrenthold's design(186MPa). The results show that the optimal design of EML meets the design requirements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4713-4718
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• 2013

Nowadays, three-dimensional computer added design(3D CAD) tool are widely and actively used for design of mechanical machine. Because using the tool is more effective to understand design concept and to collaborate with other operation than using two-dimensional design tool. In this study, the 3D CAD tool which is called I-DEAS was applied for three-dimensional modeling of main parts and assembling of modeled parts for identification the entire shape of a injection molding machine. In addition, a study was also performed regarding reduction for the weight of main plates for saving production cost and energy in the machine. A finite element method(FEM) program in I-DEAS tool was used for the improvement study. First, the current main plates were structural analysed and then the plate deformations, weak regions and stress distributions were graped. By the FEM results, the 2nd improved designing of the plates was conducted such as reinforcement or slimming of the plate wall thickness. The 2nd structural FEM was performed for verification of the redesigned plates and then the FEM results were compared with the 1st FEM's result. The weight of the main plates were averagely reduced approximately 3 - 7%. By these results, it was seemed that the improved plates have a useful availability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.248-252
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• 1999

This study examined the effects of growth retardants and midsummer drainage on lodging-related characters in direct seeding rice culture on flooded paddy surfaces. Treatments included in this study were continuous flooding, two time midsummer drainages (TTD), and inabenfide or trinexapac-ethyl application after TTD. Culm length was reduced most by 11.4cm in trinexapac-ethyl treatment after TTD, followed by 4.1cm in inabenfide treatment after TTD compared to TTD treatment. A significant reduction in culm length occurred at the 3rd internode in inabenfide treatment applied at 40 days before heading (DBH), while trinexapac-ethyl application at 8 DBH reduced the 3rd>2nd>1st internode. The culm diameter of the 4th internode was increased by the application of trinexapac-ethyl following TTD compared to TTD treatment. Thickness of culm wall was significantly increased by trinexapac-ethyl but not by inabenfide applications. Lodging index was the highest in continuous flooding and the lowest in trinexapac-ethyl treatment after TTD. Subsequently, field lodging did not occur in plots treated by trinexapac-ethyl. Rice plants subjected to midsummer drainage or growth retardants showed higher ripened grain ratio and 1000-grain weight, resulting in higher rice yield. These results indicate that trinexapac-ethyl, which can be applied at the relatively later growth stage after proper judgement of lodging occurrence, could be a useful tool for reducing lodging in direct seeding rice culture on flooded paddy fields.

• Progress in Medical Physics
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• v.16 no.1
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• pp.16-23
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• 2005

The objective of this study was to construct multi-element ultrasound applicators for the treatment of gynecologic cancer with high dose rate brachytherapy. For the treatment of uterus, piezo-ceramic crystal transducer (PZT -5A) with outer diameter of 4 mm, wall thickness of 1.3 mm, and length of 24.5 mm was selected. For the treatment of cervix or vagina, it should be possible to insert the applicator into the vagina. Thus, a cylindrical PZT -8 material with outer diameter of 24.5 mm, wall thickness of 1.3 mm, and length of 15.2 mm was selected. The operating frequencies determined by vector impedance measurement were 3.2 MHz for the PZT 5A cylinder (OD=4 mm) and 1.7 MHz for the PZT -8 cylinder (OD: 24.5 mm). The ratios of generated acoustic output power to applied electric power were 33% and 61% for the tandem type crystal and the cylinder type crystal, respectively. The radiated acoustic pressure fields from both transducers were calculated using a Matlab code and measured in water using hydrophone. There was good agreement between measured and calculated acoustic pressure field distribution. For a tandem type transducer, the calculated acoustic pressure field decreased from 0.023 MPa at 10 mm to 0.010 Mpa at 30 mm, the reduction of 57%. For the cylinder type transducer which will be used for the treatment of vagina showed 78% reduction at 15 mm and 66% at 25 mm as compared to values at 5 mm from the surface. Based on the characteristics of the transducers, this study demonstrated the possibility of using the crystals as a heating source. Finally, a 3-element and 4-element prototype applicators were constructed. The 3-element applicator is 75 mm long and 4 mm thick and will be used for the treatment of uterus. The 4-element applicator is 61 mm long and 24.5 mm thick and will be used for the treatment of vagina. Using these applicators, it is possible to generate enough power to increase temperature to therapeutic level.

• Animal Bioscience
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• v.34 no.3_spc
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• pp.417-426
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• 2021

Objective: Effects of inulin supplementation in diet of Haidong chicks under hypoxic conditions on production performance, intestinal morphologic change, microflora contents and the incidence of ascites were studied. Methods: Commercial male chicks (360) were randomly divided into 6 groups and were fed diets supplemented with 0, 0.05, 0.075, 0.1, 0.125, and 0.15 g/kg of inulin, respectively. Results: The body weight gain and feed intake were improved in chicks fed the diets supplemented with 0.1 and 0.125 g/kg of inulin, from d 1 to d 42 (p<0.05); moreover, blood parameters were positively affected when inulin was included in the diets and the thickness of the intestinal wall and muscle tissue in duodenum, jejunum, and ileum tended to increase (p<0.05), and the villi height and crypt depth in duodenum, jejunum, and ileum (p<0.05). Regarding the number of goblet cells in duodenum, jejunum and ileum tended to increase when chicks were fed the diets supplemented with 0.075, 0.1, 0.125, and 0.15 g/kg (p<0.05) of inulin. When chicks were fed diets supplemented with 0.75 or 0.1 g/kg of inulin, a significant reduction of Escherichia coli counts in the cecum was observed; for a contrary, a significant increment of Bifidobacterium and Lactobacillus was observed in cecum and ileum. Finally, supplementing the feed with inulin determined an overall reduction of ascites incidences in comparison to the control group. Conclusion: Thus, the results observed in the present study clearly suggest that the diet supplementation with a quantity of inulin ranging between 0.1 and 0.125 g/kg, can improve growth performances, intestinal morphology, internal microbial balance and ascites incidence, in broiler chicks raised at high altitude area. Even though these findings may be of interest for the poultry industry, they may particularly be relevant in those areas characterized by high altitude such as Northwest China regions.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.1
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• pp.7-16
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• 2016

Purpose : This study aimed to compare and evaluate between the efficiency of two respective devices, 3D-bolus and step-bolus when the devices were used for the treatment of patients whose chest walls were required to undergo the electron beam therapy after the surgical procedure of modified radical mastectomy, MRM. Materials and Methods : The treatment plan of reverse hockey stick method, using the photon beam and electron beam, had been set for six breast cancer patients and these 6 breast cancer patients were selected to be the subjects for this study. The prescribed dose of electron beam for anterior chest wall was set to be 180 cGy per treatment and both the 3D-bolus, produced using 3D printer(CubeX, 3D systems, USA) and the self-made conventional step-bolus were used respectively. The surface dose under 3D-bolus and step-bolus was measured at 5 measurement spots of iso-center, lateral, medial, superior and inferior point, using GAFCHROMIC EBT3 film (International specialty products, USA) and the measured value of dose at 5 spots was compared and analyzed. Also the respective treatment plan was devised, considering the adoption of 3D-bolus and stepbolus and the separate treatment results were compared to each other. Results : The average surface dose was 179.17 cGy when the device of 3D-bolus was adopted and 172.02 cGy when step-bolus was adopted. The average error rate against the prescribed dose of 180 cGy was -(minus) 0.47% when the device of 3D-bolus was adopted and it was -(minus) 4.43% when step-bolus was adopted. It was turned out that the maximum error rate at the point of iso-center was 2.69%, in case of 3D-bolus adoption and it was 5,54% in case of step-bolus adoption. The maximum discrepancy in terms of treatment accuracy was revealed to be about 6% when step-bolus was adopted and to be about 3% when 3D-bolus was adopted. The difference in average target dose on chest wall between 3D-bolus treatment plan and step-bolus treatment plan was shown to be insignificant as the difference was only 0.3%. However, to mention the average prescribed dose for the part of lung and heart, that of 3D-bolus was decreased by 11% for lung and by 8% for heart, compared to that of step-bolus. Conclusion : It was confirmed through this research that the dose uniformity could be improved better through the device of 3D-bolus than through the device of step-bolus, as the device of 3D-bolus, produced in consideration of the contact condition of skin surface of chest wall, could be attached to patients' skin more nicely and the thickness of chest wall can be guaranteed more accurately by the device of 3D-bolus. It is considered that 3D-bolus device can be highly appreciated clinically because 3D-bolus reduces the dose on the adjacent organs and make the normal tissues protected, while that gives no reduction of dose on chest wall.

• Progress in Medical Physics
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• v.11 no.2
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• pp.109-116
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• 2000

One consideration of radiation delivery in cervical cancer is the complication of critical organs, e.g., bladder and rectum. The absorbed dose of bladder and rectum in HDR intracavitary brachytherapy is measured indirectly with TLD dosimetry A method for the complication reduction of bladder and rectum is suggested. For two-hundred cervical cancer patients, follow-up MRI images were reviewed and distances from cervical central axis to bladder and rectum and vaginal wall thickness were measured. The sealed TLDs were placed upon the gauze packing of the ovoids and the distances to the TLDs from the ovoid center were measured in the simulation film and actual doses of bladder and rectum were calculated. From published data, maximal tolerance doses of bladder and rectum were derived and based on the permissible doses per fraction in HDR brachytherapy the packing thicknesses were determined in both directions. The required minimal packing thicknesses for bladder and rectum were 0.43 and 0.92 cm, respectively. The results were compared with computer calculation using the Meisberger polynomial approach. It is our hope this study can be used for a guideline for users in clinic in estimating critical organ dose in bladder and rectum in HDR brachytherapy in vivo dosimetry.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.307-320
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• 1998

Tunnel lining is the final support of a tunnel and reflects the results of the interaction between ground and support system. Recently it is very difficult to support and manage the tunnel because the cracks on tunnel lining cause many problems in supporting and managing tunnels. Therefore the analysis of the cracks is quite strongly required. In this study, mechanical behaviour of a tunnel lining was examined by model tests and by numerical analyses. Especially the model test was examined for double linings including shotcrete and concrete lining. The model tests were carried out under various conditions taking different loading shapes, horizontal stresses, thicknesses of linings and double lining, vault opening behind the concrete lining and rock-like medium surrounding the lining. Due to horizontal stress, compressive stress prevailed on the lining. Thus the bearing capacity of the lining increased. The existence of a vault opening behind the concrete lining reduced the bearing capacity by the similar amount of reduction of concrete lining thickness. Rock-like medium cast around the side wall of the lining restrained the deflection of the lining, and the bearing capacity for cracking and failure increased vary much. In numerical analyses a algorithm which can analysis the double lining by introduction of interface element was developed. And the results of the numerical analyses were compared with the results of the model tests.

• Progress in Medical Physics
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• v.19 no.4
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• pp.276-284
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• 2008

A computed tomography (CT) is a powerful system for the effectively fast and accurate diagnosis. The CT system, therefore, has used substantially and developed for improving the performance over the past decade, resulting in growing concerns over the radiation dose from the CT. Advanced CT techniques, such as a multidetector row CT scanner and dual energy or dual source CT, have led to new clinical applications that could result in further increases of radiation does for both patients and workers. The objective of this study was to review the international guidelines of the shielding requirements for a CT facility required for a new installation or when modifying an existing one. We used Google Search Engine to search the following keywords: computed tomography, CT regulation or shield or protection, dual energy or dual source CT, multidetector CT, CT radiation protection, and regulatory or legislation or regulation CT. In addition, we searched some special websites, that were provided for sources of radiation protection, shielding, and regulation, RSNA, AAPM, FDA, NIH, RCR, ICRP, IRPA, ICRP, IAEA, WHO (See in Table 1 for full explanations of the abbreviations). We finally summarized results of the investigated materials for each country. The shielding requirement of the CT room design was very well documented in the countries of Canada, United States of America, and United Kingdom. The wall thickness of the CT room could be obtained by the iso-exposure contour or the point source method. Most of documents provided by international organizations were explained in importance of radiation reduction in patients and workers. However, there were no directly-related documents of shielding and patient exposure dose for the dual energy CT system. Based international guidelines, the guideline of the CT room shielding and radiation reduction in patients and workers should be specified for all kinds of CT systems, included in the dual energy CT. We proposed some possible strategies in this paper.