• Journal of radiological science and technology
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• v.37 no.4
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• pp.323-330
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• 2014

Image reconstruction is one of the most important processes in CT (Computed tomography) technology. For fast scanning and low dose to the objects, iterative reconstruction is becoming more and more important. In the implementation of iterative reconstruction, projection and backprojection processes are considered to be indispensable parts. However, many approaches for projection and backprojection may result severe image artifacts due to their discrete characteristics and affects the reconstructed image quality. Thus, new approaches for projection and backprojection are highly demanded these days. In this paper, distance-driven approach was evaluated and compared with other conventional methods. The numerical simulator was developed to make the phantoms, and projection and backprojection images were compared using these approaches. As a result, it turned out that there are less artifacts during projection and backprojection in parallel and fan beam geometry.

• Food Science of Animal Resources
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• v.23 no.2
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• pp.137-144
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• 2003

This study was carried out to investigate safety evaluation of IGEs separated and refined from bovine milk and commercial recombinant human IGFs. In order to evaluate toxicity of these samples, acute toxicity test and short term toxicity test were investigated with IGF-I separated and refined from colostrum and commercial recombinant human IGF-I from R&D systems company. for acute toxicity test, we selected recombinant human IGF-I from R&D systems company and establish one control group and three dose-level groups(0, 10, 20 and 50 $\mu\textrm{g}$ per rat). We have intravenously injected tail of rats with selected sample once. After 20 days, pathological cellular tissue analyses were investigated with liver, kidney and spleen of 12 rats in all test groups. However, Morbid tissue and abnormal statistical results were not discovered in all cellular tissues. For short term toxicity test, we selected IGF-I separated and refined from colostrum and establish one control group and three dose-level groups(0, 5, 10 and 15 $\mu\textrm{g}$/day per rat). Rats were orally injected with selected sample once a day during two weeks. After short term toxicity test period, Pathological cellular tissue analyses were investigate with liver, kidney and spleen of 12 rats in all test groups. However, Morbid tissue and abnormal statistical results were not discovered in all cellular tissues. These results suggest that IGF-I treated groups show no significant toxicological findings with changes of body weight, food consumption, water consumption, and pathological findings compared with control groups.

• Applied Microscopy
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• v.39 no.2
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• pp.199-204
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• 2009

In this study, we observed the effects of repeated perms on the morphology of virgin hair of a healthy thirteen year-old girl with scanning electron microscopy. After the first treatment, the outer parts of cuticle cell were broken unevenly and roughly. Cuticle cells were lifted upward making a space. After the third treatment, cuticle cells were lifted off one another and the folded scales showed irregular surface areas. Broken pieces of cells were stuck on the surface and an empty hole was present in the endocuticle of the cytoplasm. We observed that cortex separated from cuticle layer more easilywith repeated treatments.

• Journal of fish pathology
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• v.9 no.1
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• pp.95-109
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• 1996

This work was carried out to investigate the functional heterogeneity of peripheral blood lymphocytes(PBLs) in carp, Cyprinus carpio. PHA, Con A, LPS and BCG were injected intraperitoneally into carp to determine the blastogenic response and rosette formation activity. In each group of fish treated with stimulators, the cell numbers and DNA contents of lymphocytes were higher than those of untreated control group and reached the highest level between 1 week and 2 weeks after injection with mitogens. These results showed that BCG and Con A were strong stimulators of proliferation compared to PHA and LPS. However, PHA-treated fish twice showed the highest rosette formation response among the consecutive stimulations with the same mitogen. Alase, the results on consecutive mitogen stimulation revealed that carps reinjected by different mitogens led to an increased stimulation higher than the one reinjected after 1 week with same mitogen. It seems that different mitogens may stimulate different cell populations and implies functionally separated subpopulations of lymphocytes in carp.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.3
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• pp.261-268
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• 2001

An investigation on nondestructive evaluation of thermal stress-nduced damage in the composite laminates (3mm in thickness and $[+45_6/-45_6]_s$ lay-up angles) has been performed using the thermo-acoustic emission technique. Reduction of thermo-AE events due to repetitive thermal load cycles showed a Kaiser effect. An analysis of the thermo-AE behavior determined the stress free temperature of composite laminates. Fiber fracture and matrix cracks were observed using the optical microscopy, scanning electron microscopy and ultrasonic C-sean. Short-Time Fourier Transform of thermo-AE signals offered the time-frequency characteristics which might classily the thermo-AE as three different types to estimate the damage processes of the composites.

• Korean Journal of Materials Research
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• v.10 no.2
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• pp.128-137
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• 2000

A study has been made to investigate the effects of hot isostatic pressing(HIPing) on the microstructure and high temperature fatigue lives of the IN738LC, Ni-base superalloy used in turbine blades, with emphasis on the elimination of casting microporosity and fatigue damage through HIP treatments. Microstructure was observed using OM, SEM and the fatigue life was investigated with rotate bending fatigue tester. The results show that the fatigue lives of properly HIP-processed specimens could be extended be extended by a factor of about sixty. In contrast, no comparable life improvement was achieved with heat treatment only. The repetitive HIP treatment was shown to be very effective as a means of rejuvenating the fatigue life of intentionally fatigue-damaged IN738LC by restoration of the initial alloy microstructure and additional removal of fine casting defects which remained in the HIP-processed material.

• Polymer(Korea)
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• v.38 no.5
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• pp.650-655
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• 2014

The degradation characteristics of perfluoropolyether (PFPE) derivatives currently being used as computer hard disk lubricants have been investigated. Especially, we considered the effects of end group on degradation behavior of PFPE derivatives. It was found that the degradation of PFPE derivatives in the presence of $Al_2O_3$ involves two degradation mechanisms such as thermal degradation and Lewis acid disproportionation by $AlF_3$ which was mainly formed by oxide-to-halide reaction between $Al_2O_3$ and the degraded PFPE. The end groups were strongly related to Lewis acid disproportionation of PFPE derivatives, and it is due to the difference of electron donating ability in the each end groups. Even if PFPE derivatives have same repeating unit in the main chain, Lewis acid disproportionation was prohibited by higher electron donating ability by the end group which caused the high electron density at the acetal group in the repeating unit.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.1
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• pp.77-83
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• 2019

With the recent development of medical technology, the diagnosis rate of type 1 diabetes is increasing and patients are increasing. However, diabetes education content is not aligned with the interest level of children. As a result of the interviews with experts, It was found that the measures of coping with the change of blood sugar and the behavior therapy require steady and repetitive learning. Therefore, this study proposes Edutainment content which can be repeatedly Learned by 10~11year old children. For effective learning, the contents of the laboratory practice were constructed and the hybrid method was used for the repetitive learning. Usability test showed that this configuration is effective. This study is expected to contribute to the study of diabetic education content that is suitable for the children's level of understanding which will be developed easily in the future.

• Archives of Hand and Microsurgery
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• v.24 no.1
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• pp.63-67
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• 2019

Spontaneous rupture of the extensor pollicis longus (EPL) tendon can occur in the 3rd extensor compartment after a distal radius fracture involving Lister's tubercle, steroid injections, or rheumatoid arthritis. We report a case of spontaneous rupture of the EPL tendon in a 26-year-old male patient who played a rhythm game, which requires repetitive wrist motions to play the drums. We also provide a comprehensive literature review along with the case report. From the authors' point of view, excessive and repetitive motion of the wrist, as shown in our case, can be a potential cause of spontaneous rupture of the EPL tendon.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.331-338
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• 2008

A new ground water sampler was developed and evaluated for target depth sampling under most rigorous field conditions. This new concept sampler comprises an air-cylinder, a hypodermic needle and a sampling bottle. Pressurized air or nitrogen gas can be used as a mechanical power source to operate the sampler. The air-cylinder is used to jab the hypodermic needle into the rubber cap of the sampling bottle. The hypodermic needle functions as a pathway to inject groundwater into the sampling bottle. Field test was conducted in a seawater intrusion monitoring well located at Handong district of Jeju Island. Water qualities in this well are periodically changed from the effects of sea water. Water sampling fir the same target depth in this well were tried at various times, and variations in electrical conductivity and pressure at the inside and outside of the sampler were measured using CTD divers. We found that the device could collect water samples only when it was actuated, and the pattern and range of variations in electrical conductivities and pressures measured at the inside and outside of the sampler were nearly identical. These results indicate that water samples using the sampler presented in this study represent correctly water qualities in which the samplings were made at a specific target depth in a well.