• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.311-311
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• 2009

Carbon nanotubes (CNTs) belong to an ideal material for field emitters because of their superior electrical, mechanical, and chemical properties together with unique geometric features. Several applications of CNTs to field emitters have been demonstrated in electron emission devices such as field emission display (FED), backlight unit (BLU), X-ray source, etc. In this study, we fabricated a CNT cathode by using filtration processes. First, an aqueous CNT solution was prepared by ultrasonically dispersing purified single-walled CNTs (SWCNTs) in deionized water with sodium dodecyl sulfate (SDS). The aqueous CNT solution in a milliliter or even several tens of micro-litters was filtered by an alumina membrane through the vacuum filtration, and an ultra-thin CNT film was formed onto the alumina membrane. Thereafter, the alumina membrane was solvated by acetone, and the floating CNT film was easily transferred to indium-tin-oxide (ITO) glass substrate in an area defined as 1 cm with a film mask. The CNT film was subjected to an activation process with an adhesive roller, erecting the CNTs up to serve as electron emitters. In order to measure their luminance characteristics, an ITO-coated glass substrate having phosphor was employed as an anode plate. Our field emitter array (FEA) was fairly transparent unlike conventional FEAs, which enabled light to emit not only through the anode frontside but also through the cathode backside, where luminace on the cathode backside was higher than that on the anode frontside. Futhermore, we added a reflecting metal layer to cathode or anode side to enhance the luminance of light passing through the other side. In one case, the metal layer was formed onto the bottom face of the cathode substrate and reflected the light back so that light passed only through the anode substrate. In the other case, the reflecting layer coated on the anode substrate made all light go only through the cathode substrate. Among the two cases, the latter showed higher luminance than the former. This study will discuss the morphologies and field emission characteristics of CNT emitters according to the experimental parameters in fabricating the lamps emitting light on the both sides or only on the either side.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.959-965
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• 2014

In the present study, we aimed to obtain design data that can be used for the side members of lightweight cars by experimentally examining the types of effects that the changes in the section shape and outermost layer of an aluminum (Al)/carbon fiber reinforced plastic (CFRP) composite structural member have on its collapse characteristics. We have drawn the following conclusions based on the test results: The circular Al/CFRP composite impact-absorbing member in which the outermost layer angle was laminated at $0^{\circ}$ was observed to be 52.9 and 49.93 higher than that of the square and hat-shaped members, respectively. In addition, the energy absorption characteristic of the circular Al/CFRP composite impact-absorbing member in which the outermost layer angle was laminated at $90^{\circ}$ was observed to be 50.49 and 49.2 higher than that of the square and hat-shaped members, respectively.

• Research in Plant Disease
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• v.21 no.1
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• pp.27-31
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• 2015

In April 2014, Fusarium wilt was found on kohlrabi seedlings in Iksan, Korea. Symptoms included wilting of foliage, drying and withering of older leaves, and stunting of the plants. The infected plants eventually died during growth. Colonies on potato dextrose agar were pinkish white, and felted with cottony and aerial mycelium. Macroconidia were falcate to almost straight, thin walled and usually 3-septate. Microconidia were usually formed abundantly in false-heads on short monophialides on the hyphae and were hyaline, smooth, oval to ellipsoidal, aseptate or medianly 1-septate, very occasionally 2-septate, slightly constricted at the septa, $4-11{\times}2.5-5{\mu}m$. On the basis of the morphological characteristics and phylogenetic analyses of molecular markers (internal transcribed spacer rDNA and translation elongation factor $1{\alpha}$), the fungus was identified as Fusarium oxysporum. Pathogenicity of a representative isolate was proved by artificial inoculation, fulfilling Koch's postulates. To our knowledge, this is the first report on the occurrence of Fusarium oxysporum on kohlrabi in Korea.

• Journal of Korean Society of Steel Construction
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• v.25 no.5
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• pp.519-530
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• 2013

Cyclic tests on modular building units for low-rise buildings composed of stud panels and a light-weight steel perimeter frame, were performed to evaluate the earthquake resistance such as stiffness, load-carrying capacity, ductility, and energy dissipation per load cycle. The strap-braced and sheeted stud panels were used as the primary lateral load-resistant element of the modular building units. Test results showed that the modular building units using the strap-braced and sheeted stud panels exhibited excellent post-yield ductile behaviors. The maximum drift ratios were greater than 5.37% and the displacement ductility ratios were greater than 5.76. However, the energy dissipation per load cycle was poor due to severe pinching during cyclic loading. Nominal strength, stiffness, and yield displacement of the modular building units were predicted based on plastic mechanisms. The predictions reasonably and conservatively correlated with the test results. However, the elastic stiffness of the strap-braced stud panel was significantly overestimated. For conservative design, the elastic stiffness of the strap-braced stud panel needs be decreased to 50% of the nominal value.

• Tuberculosis and Respiratory Diseases
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• v.60 no.4
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• pp.464-468
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• 2006

The incidence of Mycobacterium kansasii pulmonary diseases are on the increase in Korea with the higher probability of occurrence in middle-aged and older men with underlying lung diseases Among nontuberculosus mycobacterial (NTM) infections, the clinical features of M. kansasii pulmonary infection are most similar to those of tuberculosis (TB). The chest radiographic findings of M. kansasii infection are almost indistinguishable from those of M. tuberculosis (predominance of an upper lobe infiltration and cavitary lesions), even though some suggest that cavities are more commonly thin-walled and have less surrounding infiltration than those of typical TB lesions. Although there are reports on the rare manifestations of M. kansasii infections, such as endobronchial ulcer, arthritis, empyema, cutaneous and mediastinal lymphadenitis, cellulites and osteomyelitis, the association with bronchial anthracofibrosis has not yet been reported. This report describes the first case of M. kansasii infection presenting as a lung mass in the right lower lobe with accompanying bronchial anthracofibrosis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.2
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• pp.127-134
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• 2020

High supersonic aircraft are exposed to high temperature environments by aerodynamic heating during supersonic flight. Thermal protection system structures such as double-panel structures are used on the skin of the fuselage and wings to prevent the transfer of high heat into the interior of an aircraft. The thin-walled double-panel skin can be exposed to acoustic loads by supersonic aircraft's high power engine noise and jet flow noise, which can cause sonic fatigue damage. Therefore, it is necessary to examine the behavior of supersonic aircraft skin structure under thermal-acoustic load and to predict fatigue life. In this paper, we designed and fabricated thermal-acoustic test equipment to simulate thermal-acoustic load. Thermal-acoustic testing of the titanium specimen under thermal-acoustic load was performed. The analytical model was verified by comparing the thermal-acoustic test results with the finite element analysis results.

• Research in Plant Disease
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• v.12 no.3
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• pp.290-293
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• 2006

A fruit rot of sweet persimmon(Diospyros kaki cv. 'Fuyu') that infected with blue mold was found during the storage and transport in Jinju Gyeongnam Province, Korea. Fruit surfaces that infected with the fungus were formed water soaked lesion at first then gradually colonized with the fungus and formed mycelial mats. From the point of infection, fruits become sunken and mostly ruptured. The pathogenic fungus was isolated from infected fruits and cultured on potato dextrose agar. The colonies of the pathogenic fungi were white at frist then became greyish green on malt extract agar. Conidia were ellipsoidal and $2.6{\sim}3.8{\times}2.4{\sim}3.8{\mu}m$ in size. Phialides were ampulliform, verticilate of 3-7, $8.0{\sim}9.2{\times}2.0{\sim}3.0{\mu}m$ in size. Metulae were verticils of 2-4, smooth, $9.0{\sim}12.6{\times}3.0{\sim}4.6{\mu}m$ in size. Ramuli were groups 1-3, smooth, $11.0{\sim}17.6{\times}2.3{\sim}3.0{\mu}m$ in size. Rami were groups 1-2, $7.5{\sim}32.6{\times}2.6{\sim}4.2{\mu}m$ in size. Stipes were septate, smooth, thin walled, $56{\sim}302{\times}2.8{\sim}4.0{\mu}m$ in size. Penicilli were mostly quaterverticillate. Based on the cultural and mycological characteristics as well as pathogenicity test on host plants, the fungus was identified as Penicillium expansum. This is the first report on the blue mold of sweet persimmon(Diospyros kaki) caused by P. expansum in Korea.

• Research in Plant Disease
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• v.24 no.1
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• pp.75-80
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• 2018

From 2014 to 2016, Fusarium wilt disease was found on fassionfruit in Iksan and Jeju, Korea. Symptoms included wilting of foliage, drying and withering of leaves, and stunting of the plants. The infected plants eventually died during growth. Colonies on potato dextrose agar were pinkish white, and felted with cottony and aerial mycelia with 35 mm after one week. Macroconidia were falcate to almost straight, thin-walled and usually 2-3 septate. Microconidia were usually formed on monophialides of the hyphae and were hyaline, smooth, oval to ellipsoidal, aseptate or medianly 1-septate, very occasionally 2-septate, slightly constricted at the septa, $3-12{\times}2.5-6{\mu}m$. On the basis of the morphological characteristics and phylogenetic analyses of two molecular markers, internal transcribed spacer rDNA and translation elongation factor $1{\alpha}$, the fungus was identified as Fusarium oxysporum. Pathogenicity of a representative isolate was proved by artificial inoculation, fulfilling Koch's postulates. To our knowledge, this is the first report on the occurrence of F. oxysporum on fassionfruit in Korea.

• Journal of Navigation and Port Research
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• v.31 no.5 s.121
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• pp.435-445
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• 2007

Ship structures are thin-walled structures and lots of cutouts, for example, of inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed. In the present paper, we investigated several kinds of perforated stiffened model from actual ship structure and series of elasto-plastic large deflection analyses were performed to investigate into the influence of perforation on the buckling and ultimate strength of the perforated stiffened plate varying the cutout ratio, web height, thickness and type of cross-section by commercial FEA program(ANSYS). Closed-form formulas for predicting the ultimate strength of the perforated stiffened plate are empirically derived by curve fitting based on the Finite Element Analysis results. These formulas are used to evaluate the ultimate strength, which showed good correlation with FEM results. These results will be useful for evaluating the ultimate strength of the perforated stiffened plate in the preliminary design.

• Applied Microscopy
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• v.40 no.4
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• pp.237-244
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• 2010

Utricularia forms small, but complex carnivorous trap along the stem either in water or in soil depending upon species. The shapes and sizes of the traps, appendages, and trichomes are known to differ among aquatic, terrestrial and epiphytic species. In the present study, the morphology and microstructure of the trap in aquatic Utricularia japonica and terrestrial U. livida were examined using light and electron microscopy. The aim of this study was to compare the characteristics of trap features between the aquatic and terrestrial species. The trap was found to be comprised of a thin walled bladder with numerous capitate trichomes, two-armed bifid and four-armed quadrifid glands in both species; however, the traps of the two species were different in size, and number and morphology of the trichomes and glands. Aquatic Utricularia was chlorenchymatous with chloroplasts distributed throughout the body, whereas the terrestrial species was translucent without plastids due to an adaptation to underground habitats. Furthermore, the former differed considerably in that the traps developed antenna and appendages around the entrance area. A peculiar trap entrance was also noted in U. livida, which exhibited radiating rows of various trichomes within funnel-shaped tissue. A large number of glandular trichomes covered the entrance area and door surface with four trigger hairs each in the aquatic form but only two in the terrestrial form. The glandular trichomes near the door secreted a large amount of mucilage that temporarily composed the velum in the U. japonica, however, it was not observed in the terrestrial species. All of the aforementioned features were highly related in their structure and function during carnivorous mechanism in Utricularia. The current findings provide important data for further comparison of the different life forms within Utricularia.