• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.60-63
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• 2002

Metal/intermetallic laminated composites have been manufactured by SHS reactions between Ni and Al elemental metal foils. Microstructure showed that the intermetallic volume fraction was 55%, 45%, 35% in the 1:1, 2:1, 4:1 thickness ratio(Ni:Al) specimen and the main phases of the intermetallic were transformed from $Ni_2Al_3$ to NiAl when the thickness ratio was increased. Tensile strength and elongation were increased when the volume fraction of Ni metallic phase was increased. Under assumptions of isostrain condition, the tensile strength of metal/intermetallic laminated composites didn't obey the ROM due to the thermal residual stress and this was confirmed by X-ray residual stress analysis. Fracture toughness results by the SENB test showed R-curves with upward curvature based on LSB condition. Bridging stress based on LSB condition was determined by the curve fitting analysis, In-situ observed microstructure during fracture test showed that the various bridging mechanism such as crack bridging, crack branching and ductile failure of metallic layer were occurred

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.237-240
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• 2004

High strain-rate deformation behavior of NiAl/Ni micro-laminated composites was characterized by split hopkins on pressure bar(SHPB). When the strain rate increased, the compressive stress of micro-laminated composites were increased a little. When the intermetallic volume fraction increased, the compressive stress of micro-laminated composites increased linearly irrespective of strain rate. Absorbed energy during the quasi-static and SHPB tests was calculated from the integrated area of stress-strain curve. Absorbed energy of micro-laminated composites deviated from the linearity in terms of the intermetallic volume fraction but merged to the value of intermetallic as the strain rate increased. This was due to high tendency of intermetallic layer for the localization of shear deformation at high strain rate. Microstructure showing adibatic shear band(ASB) confirmed that the shear strain calculated from the misalignment angle of each layer increased and ASB width decreased when the intermetallic volume fraction. Simulation test impacted by tungsten heavy alloy cylinder resulted that the absorbed energies multiplied by damaged volume of micro-laminated composites were decreased as the intermetallic volume fraction increased. Fracture mode were changed from delamination to single fracture when the intermetallic volume fraction and this results were good matched with previous results[l] obtained from the fracture tests.

• Korean Journal of Community Nutrition
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• v.14 no.5
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• pp.531-544
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• 2009

This study was conducted to survey multiple factors of aversion to vegetables and preferences for vegetable-related recipes in school meal services among elementary school children in order to help develop various menus and recipes for school meal services. Questionnaire survey was carried out with the study subjects, who were 401 children in 6th grade attending elementary schools in Chonnam and Kwangju metropolitan regions. Results from the survey can be summarized as follows: 65.1% of respondents answered they try to eat vegetables and other namul side dishes served in school meal service for health. As for the frequency of taking vegetables and namul side dishes out of daily meals, 47.4% of respondents chose 'once or twice'. The reasons for aversion to vegetables in boys were taste and cooking method, while girls were taste and feeling between teeth. In boys there were no differences between regions of Kwangju and Chonnam but the tendency of aversion to vegetables was significantly high in girls. As for the aspects of vegetable aversion of subjects, 46.9% of respondents took up 'black & purple' in the unfavorable color of vegetables. 49.1% in 'bitterness' and 39.2% in 'greasiness' were in terms of the aversive taste of vegetables. The aversive vegetable recipes were 58.6% in 'raw & seasoned' and the unfavorable feeling of vegetables were 53.1% in 'squashiness'. There were differences between regions of Kwangju and Chonnam with boys in color and cooking method in girls. Results from the survey on their preferences for vegetable recipes showed that leafy vegetables like crown daisy (raw/slightly seasoned) and pak choi (broth/pot stew) fell to the most aversive category, while bean sprouts (broth/pot stew) were chosen as the most favorable one. Among root vegetables bell-flowers were found to belong to the least preferred recipe, while potatoes were proven to be most preferable in terms of recipes. As for fruit vegetables and other vegetables, all respondents didn't like 'fatsia shoots' vegetable and it's cooking method and they preferred 'green pumpkins (broth/pot stew)'. In respect of mushrooms, enoki mushroom (broth/pot stew) was found most preferred and had high tendency of preferences in boys and girls in Kwangju compared with Chonnam region. The study results indicated that respondents did not show big differences in factors influencing them to be averse to vegetables and their preferences for vegetable recipes depending on regions. In order to have high preference and intake in children's diets, it needs to study in reform of menu about using namul or vegetables mixed with meats and fruits that children preferred or applying roasted and fried other less than namul.

• The Korean Journal of Mycology
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• v.37 no.2
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• pp.144-149
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• 2009

The occurrences of the major diseases and the densities of air-born microbes were surveyed in the cultivation facilities for oyster mushroom (Pleurotus ostreatus), king oyster mushroom (Pleurotus eryngii), and enoki mushroom (Flammulina velutipes) in different areas of Korea. Green mold disease was most often developed in oyster mushroom bed cultivation with the disease incidence rate of approximate 10% while the disease incidences from bottle and plastic envelop cultivation were less than 1~2%. In the bed cultivation, the major air-born microbes in the growth room were Aspergillus, Penicillium, Trichoderma, and Curvularia with the total fungal population density of 567~1,297 CFU/$m^3$ . However, only Trichoderma and Penicillium were detected in the growth rooms and innoculation rooms of bottle and plastic envelop cultivation with the densities of 350~700 CFU/$m^3$ and 160~260 CFU/$m^3$, respectively. The bacterial diseases become evident in the growth rooms of bottle and plastic envelop cultivation with the approximate incidence rate of 10%. The identified bacterial species were Brevibacillus levelkil, Rhizobium radiobacter, Brevundimonas vesicularis, Pseudomonas mosselii, Microbacterium testaceum. Sphingomonas panmi, Sphingomonas yabuuchiae, Paracocus dinitrificans, Curtobacterium flaccumfaciens pv. flaccumfaciens and some unidentified bacteria with the densities of 40~6,359 CFU/$m^3$ in the growth rooms and 9 CFU/$m^3$ in the inoculation room. This study indicated that the green mold disease by fungal strains was the major mushroom disease in the bed cultivation and suggested that the contamination of bacteria and fungi together in the growth media could result in severe production loss. The plastic envelope and bottle cultivation were evidenced to be less susceptible to such contaminations.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.666-672
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• 2012

The present study was carried out in order to assess the dietary exposure as well as the risk for lead (Pb) and cadmium (Cd) exposure through mushrooms among the Korean population. Various samples (n=536) covering 17 kinds of mushrooms were collected from retail outlets and markets in Korea. The contents of Pb were 0.005 (King oyster)-0.026 (Matsutake) mg/kg in raw mushrooms and 0.014 (Oyster)-16.411 (Manna lichen) mg/kg in dry mushrooms, respectively. The contents of Cd were 0.002 (Enoki)-0.205 (Hericium erinaciium) mg/kg in raw mushrooms and 0.021 (Vegetable worms)-2.650 (Agaricus blazei Muill) mg/kg in dry mushrooms, respectively. The mean dietary exposure of Pb for the general population was $0.053{\mu}g/day$, taking 0.03% of provisional tolerable weekly intake (PTWI). The mean dietary exposure of Cd for the general population was $0.168{\mu}g/day$, corresponding to 0.37% of provisional tolerable monthly intake (PTMI). Therefore, the level of the overall dietary exposure to heavy metals through mushroom for the Korean population was far below the recommended JECFA levels, indicating little possibility of concern.

• Journal of Mushroom
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• v.12 no.3
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• pp.201-208
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• 2014

The separation of the bacteria inhibiting Trichoderma sp. mold, the strain causing blue mold disease that occurs frequently when cultivating mushroom while carrying out the efficient fermentation of mushroom medium, from the growth was done. In about 200 strains isolated primarily from fungus garden samples, 6 strains were secondly isolated, which had fast growth rates and a clear zone on the plate medium of SM, AM, and CM. Among the 6 strains isolated, the C-1 strain showed high enzymatic activity of cellulase, amylase, and protease, and strong antibacterial activity for the T. virens and T. harzianum, selected finally. The selected C-1 strain was identified as Paenibacillus polymyxaby the result of the identification by Bergey's Manual of Systematic Bacteriology and the analysis of the nucleotide sequence of 16S rRNA, and named as P. polymyxa CK-1. In reviewing the growth conditions of the P. polymyxa CK-1 strain, the optimum cultivation temperature was $45^{\circ}C$, and the optimum pH for growth was in the range of 6.0~7.0. Appropriate incubation time of P. polymyxa CK-1 for the growth inhibition of the fungus T. virens and T. harzianum was 22 to 36 hours. And the fungal growth was not observed, even when leaving two molds inoculated on each petri dishes, which were treated with 24 hour culture solution of P. polymyxa CK-1 strain for 10 days. As a result of studying the thermal stability of the antagonists produced by the P. polymyxa CK-1 strain, no mycelial growth of the two fungi was observed in the test group treated for 20 minutes at $60^{\circ}C$ and $100^{\circ}C$, but mycelial growth was slightly observed in the test group treated for 20 minutes at $121^{\circ}C$. As aresult of reviewing the impact of the P. polymyxa CK-1 culture medium on mushroom mycelial growth, it showed no effect on a variety of mushroom mycelial growth including enoki mushroom and shiitake mushroom.