• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.1
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• pp.62-67
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• 2011

Nanoparticles-coated and impact-damaged carbon-fiber reinforced plastics(CFRP) laminates were tested under compression-after-impact(CAI) mode and the propagation of damage due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. CFRP laminates were made of carbon prepregs prepared by coating of conductive nano-particles directly on the fibers and the coupons were subjected to simulated lightning strikes with a high voltage/current impulse of 10~40 kA within a few microseconds. The effects of nano-particles coating and the degree of damage induced by the simulated lightning strikes on the AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terms of damage area by using ultrasonic C-scan images. From the results assessed during the CAI tests of damaged CFRP showed that AE monitoring appeared to be very useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1982.05a
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• pp.6.2-7
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• 1982

We have observed foreign bodies in food and air passage in 270 cases during the period from Sep. 1976 to Aug. 1981 in E.N.T. department of Han Gang Sacred Heart Hospital. The following results were obtained. 1) Distribution of location was 256 cases (94.8%) in food passage and 14 cases(5.2%) in air passage. 2) Age distribution was predominent in under 5 years old showing 198 cases(77.7%) in food passage and 10 cases (71.4%) in air passage. Under 5 years old group in the cases of food passage, coin was the most frequent material : 175 cases(87.9%), and in the cases of air passage, plastic material was the most frequent material : 5 cases(50.0%). Over 40 years old group in the cases of food passage, bony pieces was the most frequent material : 8 cases(47.1%), and meats was second frequent material: 6 cases. 3) Male seems to be more frequently involved than female in cases of food and air passage. Food passage - Male: Female - 151 : 105 (1.4:1) Air passage - Male : Female - 10:4 (2.5:1) 4) Coin was the most frequent foreign body in food Passage (199 cases-77.7%). Others were metals, bony pices, and meats. Plastic material was the most frequent foreign body in air passage (7 cases-50%). 5) In the locality of food passage, the first narrowing of the esophagus was the most frequent site, and air passage, the bronchus-especially right bronchus-was the most frequent site. 6) During of lodgement was 218 cases (85.2%) within 24 hours in food passage and 9 cases (64.3%) within 24 hours in air passage, and in air passage one case visited 5 months later after the accident.

• Fire Science and Engineering
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• v.20 no.3 s.63
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• pp.35-41
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• 2006

In this study, we presented the problems in the insulation cover of 22.9kV transformer bushing through investigating actual conditions. After thermal stress applied to the insulation cover, deterioration patterns, thermogravimetric and infrared characteristics were analyzed, and the results were applied to the cause analysis of accidents and judgement of safety. The insulation covers are used to protect exposed terminals of transformer, but they had improper size and length. Therefore, they could not show efficient insulation function. In case that thermal stress of $150^{\circ}C$ was applied to the insulation covers, plastic insulation covers(A, B, D, E) damaged severely, whereas rubber insulation cover(C) showed normal shapes. In the result of thermogravimetric analysis, the thermal gravity of plastic covers(A) decreased about 33.3% at $307.8^{\circ}C\;to\;405.9^{\circ}C$. and he thermal gravity of rubber covers (C) decreased about 53.7% at $258.8^{\circ}C\;to\;32.9^{\circ}C$. In the result of FT-IR analysis, plastic covers showed peaks characteristic of $CH_2,\;CH_3$, C=O and C=C bonds, whereas rubber covers showed peaks characteristic of OH, $CH_2,\;CH_3$, C=O, C=N and C=C bonds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.419-425
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• 2014

This study applied finite element analysis (FEA) to the body frame of the 200-meter class multi-legged subsea walking robot known as Crabster (CR200). The body frame of the CR200 is modeled after the ribcage of a human so that it can disperse applied external loads. It is made of carbon-fiber-reinforced plastic (CFRP). Therefore, the frame is lighter and stronger than it would be if it were made of other conventional materials. In order to perform FEA for the CFRP body frame, we applied the material properties of the CFRP as obtained from a specimen test to an FE model of CFRP frame. Finally, we performed FEA with respect to the load conditions encountered when the robot is launched into and recovered from the sea. Also, we performed FEA for the frame, assuming that it was fabricated using a conventional material, in order to compare its characteristics with CFRP.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.256-260
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• 1999

Purpose : An investigation has been carried out on the factors which affect the response reading of thermoluminescent dosimeters (TLD-100) loaded with thin material in high energy Photon. The aim of the study was to assess the energy response of TLD-100 to the therapeutic ranges of photon beam. Materials and Methods : In this technique, TLD-100 (abbreviated as TLD) chips and three different thin material (Tin, Gold, and Tissue equivalent plastic plate) which mounted on the TLD chip were used in the clinical photon beam. The thickness of each metal plates was 0.1 mm and TE plastic plate was 1 mm thick. These compared with the photon energy dependence of the sensitivities of TLD (normal chip), TLD loaded with Tin or Gold plate, for the photon energy range 6 MV to 15 MV, which was of interest in radiotherapy. Results : The enhancement of surface dose in the TLD with metal plate was clearly detected. The TLD chips with a Gold plate was found to larger response by a factor of 1.83 in 10 MV photon beam with respect to normal chip. The sensitivity of TLD loaded with Tin was less than that for normal TLD and TLD loaded with Gold. The relative sensitivity of TLD loaded with metal has little energy dependence. Conclusion : The good stability and linearity with respect to monitor units of TLD loaded with metal were demonstrated by relative measurements in high energy Photon ($6\~15$ MV) beams. The TLD laminated with metals embedded system in solid water phantom is a suitable detector for relative dose measurements in a small beam size and surface dose.

• Journal of Bio-Environment Control
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• v.9 no.3
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• pp.156-160
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• 2000

The Plasma film treated with a high electric voltage was developed to enhance flow down of condensation drops on inside plastic film. Arch type greenhouse framed with iron pipe of 25mm diameter defand 1.5mm thickness were covered with either the developed plasma film or surfactant film(control). Green pepper seedlings raised for 40 days in plug trays were transplanted at a density of 110cm by 30cm in each greenhouse. The mount of condensational water on film surface, generated by 7$0^{\circ}C$ water bath chimney systems and flew down, was collected and measured. The amount of collected water after 150 minutes was 2.56 mL.100c $m^{-2}$ and 0.94mL.100c $m^{-2}$ , respectively, in the plasma film and surfactant film-covered greenhouses. The amount of condensational water drops attached on the cover at 08:20 a.m. at 60 days filter covering was 0.34mL.100c $m^{02}$ and 0.32mL.100c $m^{-2}$ , respectively, in the plasma film- and surfactant film-covered greenhouses. Solar irradiance transmitted into greenhouse was 2.0% higher in the greenhouse covered with the plasma film tan that in the greenhouse covered with the surfactant film. Air temperature in the plasma film-covered greenhouse was higher than the surfactant film-covered greenhouse by 0.5$^{\circ}C$. However, there was no difference in relative humidity between the two greenhouse. Plant height, leaf area, dry weight and early yield showed no significant differences.s.

• Journal of the Korean Wood Science and Technology
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• v.37 no.4
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• pp.357-363
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• 2009

This study was carried out to investigate whether adhesive used in manufacturing glulam can be used to bond wood and GFRP, when considering working process and economical efficiency. The six different glulams were manufactured, changing the adhesives and the mixing ratios of the adhesives, and investigated by the block shear test and the delamination of the water soaking or boiling water soaking. The three glulams were manufactured, using the resocinol resin based adhesive, the PVAc resin based adhesive and the epoxy resin adhesive, and the other three glulams, using the adhesives mixing resocinol resin and PVAc resin. The block shear strength is higher than $7.1N/mm^2$ in all types, which is standard of KS F3021. However, in the wood failure the block shear strength was the highest as 65.9% in the PVAc. The delamination of glulams glued with PVAc adhesive, which was 1.08% in water soaking and 4.16% in boiling water soaking, was lower than 5.00% which is the standard of KS F 3021, and the adhesive strength is good. In glulams glued with only resocinol resin adhesive, the wood layers were good as 1.26% in the water soaking delamination and 0.00% in the boiling water soaking delamination. The GFRP layers were not good as 21.85% in the water soaking delamination but were good as 1.45% in the boiling water soaking delamination.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.4
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• pp.315-322
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• 1990

In order to find out the most favorable shape and structure of pot for conger eel, Astroconger myriaster(Brevoort), the box type, tube type and flat box type of net pots and the pipe type of plastic pot were prepared. Then, the ability of the pots attracting the eel into them were investigated through a tank experiment. The attracting ability was highest in the pipe type without distinction of its length, 50cm and 60cm. In the flat box type, the effective height of pot and the diameter of entrance tip turned out 5cm respectively. But the ability was very poor in the rest pots, especially in the tube type. Thus, the pipe type and flat box type of pots were employed again in a field experiment for comparing their catches with those of the conventional bamboo and plastic pots. In the experiment, the catches were the most in the pipe type and second in the flat box type. But the bamboo and plastic pots both produced comparatively low catches, showing no significant difference between them. It was therefore concluded that the pipe type of pot might be the most favorable one for catching the conger eel.

• Korean journal of food and cookery science
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• v.14 no.1
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• pp.21-24
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• 1998

The purpose of this study was to evaluate the microbiological quality of kitchen utensils in institutional foodservices in Seoul. Total plate count of plastic container, knife, wiping clothes and cutting board are 1${\times}$$10^3$-1${\times}$10/sup/5(CFU/100 $cm^2$). There were many coliforms in plastic container (2${\times}$$10^1$CFU/100 $m^2$), knife (2-3${\times}$$10^1$CFU/100 $cm^2$), wiping clothes (4-6${\times}$$10^1$CFU/100 $cm^2$) and cutting board (4-9${\times}$$10^1$CFU/100 $cm^2$). The results of microbiological test of kitchen utensils indicated that the sanitary conditions of plastic container, knife, wiping clothes and cutting board should be improved promptly. Electron microscopic observation showed that there were too many bacteria in plastic containers.

• Journal of Bio-Environment Control
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• v.25 no.3
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• pp.193-199
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• 2016

The research discussed experimental results on slip resistance force of rafter-purlin connection of plastic greenhouse and suggested a test method for evaluating slip resistance performance of the connection. Slip resistance forces were measured by four kinds of constraint conditions for specimens, for example, fixing or rolling the end of specimen. According to tests, it is noticed that constraint condition is able to significantly affect the slip resistance force. From a post-hoc comparison result, slip resistance force of test under fixing ends condition was larger than those under the other three constraint conditions. But the slip resistance force results in the fixing ends condition had greater measure of dispersion and three times of standard deviation than those from other constraint conditions. Based on the results obtained, effect of constraint condition for specimen on the slip test should be studied to enhance reliability of evaluation test of the slip resistance performance.