• Progress in Medical Physics
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• v.25 no.1
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• pp.8-14
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• 2014

The amounts of radioactive wastes to be disposed in the medical institute have been increased due to development of radiation diagnosis and therapy rapidly. They are produced mostly by the very short lived radioisotopes such as $^{18}F$ used in PET/CT, $^{99m}Tc$, $^{123}I$, $^{125}I$ and $^{201}Tl$, etc. IAEA proposed a criteria for the clearance level of waste which depends on the individual ($10{\mu}Sv/y$) and collective dose (1 man-Sv/y), and concentration of each nuclide (IAEA Safety Series No 111-P-1.1, 1992 and IAEA RS-G-1.7, 2004). Radioactive wastes of $^{18}F$, $^{99m}Tc$, $^{123}I$, $^{125}I$ and $^{201}TI$ in the several types of container like Marinelli beaker, vial and plastic, were collected to measure the concentration of the waste of each nuclide in accordance with IAEA criteria. The measurement method and procedure of determining specific activity of the wastes using gamma emitters like MCA, gamma counter and beta emitters were developed. For the efficiency calibration of the detectors, CRM (certified reference material) which has the same dimension and shape was provided by Korea Research Institute of Standards and Science (KRISS). Correction factor of the radioactivity decay was calculated based on the measurement results, and the consideration of mutual relation with theoretical equation. The result of this study will be proposed as ISO standard.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.596-599
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• 2007

A comparative Life Cycle Assessment (LCA) among three types of Electric Motor Unit (EMU) Interior Panel (IP) was conducted. A functional unit for comparative LCA is a weight of IP for 1 EMU. It is assumed that Manufacturing stage and its upstream processes, Use stage and End of Life (EoL) stage are included in the boundary of product system. For Use stage, the weight of IP causes electricity consumption. It is assumed that aluminum IP is recycled and the other IPs are incinerated at the EoL stage. As a comparison results, aluminum IP has much larger environmental impact (5.162pt) than others (FRP IP; 4.069pt, Phenol IP; 4.053pt) even though recycling consideration is included. The manufacturing stage of aluminum IP has relative big environmental impact (1.824pt) and this point make the most important difference from other IPs (FRP IP; 0.1617pt, Phenol IP; 0.4534pt)). Despite of large weight difference between FRP IP (888.96kg) and phenol IP (316kg), the final environmental impact result has only little difference (0.016pt, 0.39%). With this result, the EMU designer can choose IP with a consideration of the environmental performance of IP.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.654-658
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• 1999

To investigate an efficient microalgal feed for lariat culture of the Pacific oyster Crassostrea gigas, we prepared three types of Isochrysis aff, galbana (T-iso) : 1) freshly Harvested feed, 2) concentrated feed and 3) freeze-dried feed. The chemical compositions and fatty acid content of these feeds were evaluated and survival rate and lipid content of oyster larvae fed by these feeds were also determined. There was no significant difference in all types of feed in the gross biochemical compositions, In the fatty acid composition, the freeze-dried feed showed a significant increase in the level of polyunsaturated fatty acid (PUFA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) than freshly Harvested feed, especially EPA was 7.35-fold higher than freshly Harvested feed. The survival rate of the oyster larvae was the highest when the larvae were fed with a diet of $10\%$ freeze-dried and $90\%$ concentrated feed; it was 2.1-fold higher than that fed with freshly Harvested food alone. Thereafter, the survival rate decreased with the increased substitutions of freeze-dried food, finally equalling that fed $100\%$ freshly harvested feed at the $30\%$ substitution. Larval lipid content of the oyster was also the highest when the larvae were fed with a diet of $10\%$ freeze-dried and $90\%$ concentrated feed. This increase was by 1.6-fold ver that fed $100\%$ freshly Harvested cells. Thus feed produced during slack times, on a seedling aquaculture farm, and preparedas a freeze-dried diet can be used, mixed with concentrated feed, to supply diets more efficiently and to improve the larvae survival rate of Pacific oyster.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.197-207
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• 2011

The study aimed at examining how different reline resins affect flexural strength and flexural modulus of denture base. A total of 80 specimens ($64{\times}10{\times}3.3$ mm, according to ISO 1567:1999) of heat-polymerized resin, 40 specimens for (Lucitone199(Dentsply Int., NewYork, USA), SR Ivocap(Ivoclar AG, Schaan, Liechtenstein)) respectively, were polymerized according to the manufacturer's instructions and divided into eight groups(n = 10). Control group specimens remained intact. Specimens in the other groups were abraded on both sides to 2 mm thickness, and were relined in 1.3 mm thickness with 3 types of resins (Lucitone199(Dentsply), SR Ivocap(Ivoclar), and Rebase II(Tokuyama Co., Ltd, Tokyo, Japan)). All specimens were preserved in distilled water at $37^{\circ}C$ for 50 hours, and then were subjected to flexural strength testing in a universal testing machine using 3-point loading. A crosshead speed of 5 mm/min was used, and the distance between the supports was 50 mm. Data analyses included one-way analysis of variance(ANOVA) and the Tukey Honestly Significant Difference test (p=.05). Both heat-polymerized resin groups and auto-polymerized resin groups showed statistically low flexural strength and flexural modulus than control groups. Specimens relined with Lucitone 199 showed significantly higher flexural strength and flexural modulus than those relined with SR-Ivocap. Specimens relined with auto-polymerized resin showed significantly lower flexural strength and flexural modulus than those relined with heat-polymerized resin. Relining with heat-polymerized resins showed superior mechanical properties to relining with an auto-polymerized resin. Relining with the same heat-polymerized resin as the denture base does not affect mechanical properties of a denture. Lucitone199 using a compression-mould technique resulted in the highest flexural strength.