• Radiation Oncology Journal
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• v.13 no.3
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• pp.285-289
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• 1995

Purpose : We compared the calcualted percent depth dose curves of 6 MeV electron beam to that of measured to evaluate the usefulness of Monte-carlo simulation method in radiation physics. Materials and Methods : The radiation dose values of 6 MeV electron beam using EGS4 code with one million histories in water were compared values that were measured from the depth dose curve of electron beam irradiated by medical accelerator ML6M. The central axis dose values were calculated according to the changing field size. such as $5{\times}5,\;10{\times}10,\;15{\times}15,\;20{\times}20cm^2$. Results : The value calculated showed a very similar shape to depth dose curve. The calculated and measured value of $D_max$ at $10{\times}10cm^2$ cone is 15mm and 14mm respectively. The calculated value of the surface radiation dose rate is $65.52\%$ and measured one is $76.94\%$. The surface radiation dose rate has varied from $64.43\%$ to $66.99\%$. The calculated values of $D_max$ are in the range between 15mm and 18mm. The calculated value was fitted well with measured value around the $D_max$ area, excluding build up range and below the $90\%$ depth dose area. Conclusion : This result suggested that the calculation of dose value can be replace the direct measurement of the dose for radiation therapy. Also, EGS4 may be a very convenient program to assess the effect of radiation dose using by personal computers.

• Parasites, Hosts and Diseases
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• v.36 no.1
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• pp.7-14
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• 1998

In order to understand the action mechanism of polyhexamethylene biguanide (PHMB) to the cyst of Accnthcnloebc on the morphological basis, the cysts of four corneal isolates of Acanthanoebc were treated with minimal cysticidal concentration (MCC) of PHMB and their ultrastructural changes were examined by transmission electron microscopy. The most striking change of cysts treated with PHMB compared with normal cysts was the shrinkage of intracystic amoebae, which resulted in the separation of the plasma membrane of intracystic amoeba from endocystic wall. Subplasmalemmal lipid droplets became irregularly shaped . In severely damaged cysts, cytoplasm was aggregated and organelles were severely deformed. Cytoplasmic materials were leaked out through the damaged plasma membrane. Most cysts showed aggregation of nuclear chromatin material. Number of mitochondrial cristae was also reduced. Ecto- and endo-cystic walls were relatively well tolerated. Findings in the present study revealed that PHMB affected mainly on plasma membrane, but lesser on organellar membrane of intracystic amoeba. It seemed likely that PHMB might kill cystic forms of Accnthamoebc by similar mechanism in which this environmental biocide can damage the cell wall of Escherichia coli by binding with acidic phospholipids.

• ALGAE
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• v.29 no.2
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• pp.137-152
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• 2014

Mixotrophic protists play diverse roles in marine food webs as predators and prey. Thus, exploring mixotrophy in phototrophic protists has emerged as a critical step in understanding marine food webs and cycling of materials in marine ecosystem. To investigate the feeding of newly described mixotrophic dinoflagellate Ansanella granifera, we explored the feeding mechanism and the different types of species that A. granifera was able to feed on. In addition, we measured the growth and ingestion rates of A. granifera feeding on the prasinophyte Pyramimonas sp., the only algal prey, as a function of prey concentration. A. granifera was able to feed on heterotrophic bacteria and the cyanobacterium Synechococcus sp. However, among the 12 species of algal prey offered, A. granifera ingested only Pyramimonas sp. A. granifera ingested the algal prey cell by engulfment. With increasing mean prey concentration, the growth rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but became saturated at a concentration of $434ngCmL^{-1}$ (10,845 cells $mL^{-1}$). The maximum specific growth rate (i.e., mixotrophic growth) of A. granifera feeding on Pyramimonas sp. was $1.426d^{-1}$, at $20^{\circ}C$ under a 14 : 10 h light-dark cycle of $20{\mu}Em^{-2}s^{-1}$, while the growth rate (i.e., phototrophic growth) under similar light conditions without added prey was $0.391d^{-1}$. With increasing mean prey concentration, the ingestion rate of A. granifera feeding on Pyramimonas sp. increased rapidly, but slightly at the concentrations ${\geq}306ngCmL^{-1}$ (7,649 cells $mL^{-1}$). The maximum ingestion rate of A. granifera feeding on Pyramimonas sp. was 0.97 ng C $predator^{-1}d^{-1}$ (24.3 cells $grazer^{-1}d^{-1}$). The calculated grazing coefficients for A. granifera feeding on co-occurring Pyramimonas sp. were up to $2.78d^{-1}$. The results of the present study suggest that A. granifera can sometimes have a considerable grazing impact on the population of Pyramimonas spp.

• The Korean Journal of Nuclear Medicine Technology
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• v.21 no.1
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• pp.50-53
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• 2017

Purpose The change in uniformity due to the decreasement in dose should be known. $^{57}Co$ sealed sources are easy to manage and use as QC sources replacing $^{99m}Tc$. Overlapping sealed sources are expected to show variations in dose due to attenuation between sealed sources. Materials and Methods A total of three experiments were conducted. The first experiment is to observe the change in the degree of senescence of the $^{57}Co$ sealed source. The second experiment is to compare the single source and overlaped source at similar doses. In the third experiment, the sources of different doses were compared on each other to determine the changes due to the attenuation between the overlapping sources. Results The results of the first experiment did not exceed the acceptable range. but each crew showed a difference. There was no statistically significant difference in the measurement of uniformity on second and third experiment Conclusion It is believed that a $^{57}Co$ sealed source can be used as a superimposed source. It is not only economical but also convenient to use. daily uniformity measurements will help reduce scan time and speed up the testing process.

• Journal of the Korean Society of Food Culture
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• v.10 no.4
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• pp.321-326
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• 1995

This study was conducted to derive consumption of persimmon by the expansion of utilization of the persimmon flesh and peel. The valuable components were investigated in persimmon flesh and peel. Crude protein and fat contents in persimmon peel were higher than flesh but soluble sugar was more higher in flesh (with 71.3%) than peel (with 54.2%). Major free sugar in persimmon peel were glucose and fructose, the composition was similar to flesh. Major total amino acids in persimmon peel were glutamic acid, proline, methionine and aspartic acid. Proline, arginine, valine and alanine were relatively high in free amino acid. Oleic acid, linoleic acid and palmitic acid were the major fatty acid in persimmon peel, and the content of unsaturated fatty acid was more higher than flesh. Sugar cookies were processed using persimmon flesh and peel, when these powder were mixed with $5{\sim}10%$ to raw materials, the preference score was increased. Steamed rice cakes with persimmon were processed using persimmon flesh and peel, when sliced-dried persimmon was mixed to $10{\sim}20%$, the preference was increased, but persimmon peel was not. The quality of gruel which processed using persimmon flesh powder improved when mixed with flesh powder of 3%, rice powder, glutinous rice powder and skimmed milk, but persimmon peel was not suitable for gruel processing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4635-4642
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• 2010

Latex modification of concrete provides the material with higher flexural strength, as well as high bond strength and reduced water permeability. One of the most advantages of the very early-strength latex-modified concrete (VES-LMC) could be the similar contraction and expansion behaviour to normal concrete substrate, which enable to ensure long-term performance. The purpose of this study was to parametric nonlinear flexural nonlinear analysis of RC beam rehabilitated by VES-LMC. The results were as follows; The flexural nonlinear analysis model of RC beam overlaid by VES-LMC in ABAQUS was proposed to predict the load-deflection response, interfacial stress, and ultimate strength. The proposed FE analysis model was verified by comparison of an experimental data and the FE analysis results. The FE analysis results showed that yield point as well as flexural stiffness increased as the depth increased; the stiffness of beam overall increased as the bond stiffness became larger; the bond strength between two different materials is a key factor in composite beam. A parametric study showed that an overlay thickness was a main influencing factor to the behavior of RC beam overlaid by VES-LMC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.86-92
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• 2017

In this study, a running performance evaluation and roller rig test was conducted to evaluate the applicability of a composite bogie frame, which has the role of the primary suspension. The composite bogie frame was made of a GEP224 glass/epoxy prepreg. Vehicle dynamic analysis was carried out on the composite bogie with three different kinds of side beam thicknesses (50 mm, 80 mm, and 150 mm). From the results, the composite bogie with a side beam thickness of 80 mm satisfied all the dynamic design requirements. Although the composite bogie with the side beam thickness of 50mm also met the design requirements, its critical speed was just a 2% margin to the requirement. In contrast, the model of the side beam thickness of 150mm did not meet the ride comfort. In addition, a composite bogie frame with the side beam thickness of 80 mm was fabricated and installed on a complete bogie. Moreover, the roller rig test using the fully equipped bogie was performed to evaluate the critical speed. During the test, the lateral excitation was imposed on the wheelsets to realize the rail irregularity. There was no divergence of the lateral displacement of the wheelsets while increasing the speed. The measured critical speed was similar to the predicted result.

• Journal of Advanced Navigation Technology
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• v.22 no.4
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• pp.279-287
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• 2018

Flight tests for aircraft development and certification have higher air accidents risk than other aerospace industries. Accordingly risk identification necessary for risk management in the safety management system is a very important factor in preventing similar air accidents during flight tests. But internationally issued accident statistics are usually confined to commercial transport aircraft and they do not reflect characteristics of flight tests, also databases to hazards identification during flight tests are not established or available in Republic of Korea. Therefore, we identified flight test procedures and traced the major causes of aviation accidents based on the statistics and preventive materials for risk management which were issued by international organizations and advanced countries of aviation. A total of 312 final reports classified as flight test among air accident/incident database held by U.S. NTSB were researched and about 200 flight test hazard were identified. The results of this study will be used as basic data for establishing the safety management system of the national comprehensive flight performance test site.

• Journal of Korean Neurosurgical Society
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• v.30 no.sup2
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• pp.294-299
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• 2001

Objectives : CT-guided stereotactic evacuation for spontaneous intracerebral hemorrhage can minimize the brain damage and can be performed safely and simply under local anesthesia. But that procedure is time consuming and has a risk of rebleeding because of the stress during head pin fixation. So authors describe easy and precise guidelines for FHA of putaminal hemorrhage without stereotactic instrument. Methods and Materials : We analyzed the data of 298 patients who underwent CT-guided stereotactic aspiration of putaminal hematoma in our hospital between January 1990 and December 2000. We divided the patients into three groups according to the location of hematoma : anterior portion, middle portion and posterior portion of putamen. Total number of catheters inserted into the hematoma were 345 and there were with regard to the direction and depth of catheters. Results : Proposed guidelines of catheter insertion to putaminal hemorrhage in our institution. 1) hematoma at the anterior portion of putamen ; Direction of catheter was the midpupillary line of the eye and the point intersecting a line drawn from the burr hole to a point between external auditory meatus(EOM) and 1cm posterior to EOM. Depth of catheter was 6-6.5cm. 2) hematoma at the middle portion of putamen ; Direction of catheter was the midpupillary line of the the eye and the point intersecting a line drawn from the burr hole to a point between 1cm and 2cm posterior to EOM. Depth of catheter was 6.5-7cm. 3) hematoma at the posterior portion of putamen ; Direction of catheter was 15 degree laterally from the midpupillary line of the eye and the point intersecting a line drawn from the burr hole to a point between 2cm and 3cm posterior to EOM. Depth of catheter was 7-7.5cm. We have performed FHA of putaminal hemorrhage in 48 cases according to this guideline. All catheter were inserted exactly at the center of hematoma and average operation time was about 30 minutes. Conclusion : Our proposed guidelines for putaminal hemorrhage are considered to be safe and simple method with similar accuracy and rapid decompression compared with traditional stereotactic method. Main advantages of this technique were unnecessity of stereotactic frame application and less time requirement for hematoma removal.

• Restorative Dentistry and Endodontics
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• v.36 no.1
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• pp.19-25
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• 2011

Objectives: The purpose of this retrospective study was to evaluate the success rate of intentionally replanted mandibular second molar with C-shaped canal configurations and to access the impact of preoperative periapical lesion on the success of intentional replantation procedure. Materials and Methods: This retrospective chart review study evaluated 52 intentionally replanted mandibular second molar teeth treated at Seoul National University Dental Hospital Department of Conservative Dentistry from January 2005 to December 2007. Seventeen teeth were lost for the follow-up, and another 6 teeth did not meet inclusion criteria of C-shaped root canal configurations. Healing outcome such as success, uncertain healing, and failure after follow-up was evaluated by clinical criteria and radiographs. Results: The overall success rate was 72.4% for the 29 intentionally replanted C-shaped mandibular second molars. The success rate of replanted teeth with preoperative periapical lesions was similar to that of replanted teeth which have no periapical lesions. Conclusions: Therefore, root canal treatment failure on C-shaped mandibular second molar can be predictably treated by intentional replantation regardless of the presence of periapical lesion.