• Tribology and Lubricants
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• v.37 no.4
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• pp.136-143
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• 2021

This paper presents the loosening behavior that occurs after the application of an external load to internal and external connection types of dental implants using the finite element method. We use fastening force between an abutment and a fixture to clamp the dental implant system; however, loosening and breakage may occur owing to cyclic external loads. In this study, we considered the initial fastening condition in the pre-load analysis and then investigated the change in stress and contact surface status when applying external loads. After the application of the initial fastening load, we verified that the internal connection-type model exhibited a relatively lower stress distribution than that of the external connection-type one. Moreover, we found that the former model showed a lower stress concentration after the application of the external load. In addition, after the application of this load, we found that the higher the shear load acting on the implant system, the higher the possibility of loosening. The study results showed the change in stress distribution and contact surface according to the connection type of the dental implants and the phenomenon of loosening by cyclic loads. We expect that the results of this study will be useful for the study of reliability and design of dental implant systems.

• Smart Structures and Systems
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• v.13 no.4
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• pp.567-585
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• 2014

The piezoelectric transverse $d_{15}$ shear sensing mechanism is firstly assessed experimentally for a cantilever smart sandwich plate made of a piezoceramic axially poled patched core and glass fiber reinforced polymer composite faces. Different electrical connections are tested for the assessment of the sensor performance under a varying amplitude harmonic (at 24 Hz) force. Also, the dynamic response of the smart sandwich composite structure is monitored using different acquisition devices. The obtained experimentally sensed voltages are compared to those resulting from the benchmark three-dimensional piezoelectric coupled finite element simulations using a commercial code where realistic features, like equipotential conditions on the patches' electrodes and mechanical updating of the clamp, are considered. Numerically, it is found that the stiffness of the clamp, which is much softer than the ideal one, has an enormous influence on the sensed voltage of its adjacent patch; therefore, sensing with the patch on the free side would be more advantageous for a cantilever configuration. Apart from confirming the latter result, the plate benchmark experimental assessment showed that the parallel connection of its two oppositely poled patches has a moderate performance but better than the clamp side patch acting as an individual sensor.

• Journal of Mushroom
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• v.11 no.1
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• pp.1-8
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• 2013

In this study, twelve of Lepista nuda were collected from various localities in Korea. Also thirteen exotic L. nuda species were collected from Japan, France, Switzerland and Portugal. Spores were isolated under optical microscope. These spores were placed on the surface of YM medium for inducing to germination. Eleven mating-groups were selected by morphological characters of fruit body such as size, color and stipe patterns. Intra-isolate crosses were made between two single-spore isolates derived from mating-groups. Also, dikaryotic crossing using the isolates from L. nuda were carried out to evaluated tetrakaryon formation. Cross-mating compatibility tests also verified its dikaryotic state by microscopic or molecular genetic observation of clamp connection and Random Amplified Polymorphic DNA (RAPD) band pattern. To analyze the growth rate of hybrids and parents mycelium in dikaryons obtained from compatible mating groups were placed on PDA medium. Intra-isolate crosses determined eleven mating-groups within L. nuda. The typical clamp connection were mostly observed in mating-groups of Korean L. nuda in $K1{\times}K2$, $K1{\times}K3$, $K1{\times}K4$, $K1{\times}K6$, $K1{\times}K5$, $K2{\times}K4$, $K2{\times}K3$, $K2{\times}K6$, $K3{\times}K4$, $K4{\times}K5$, and $K4{\times}K6$. Korean L. nuda type of dikaryon, shown to cross-incompatibility with L. sordida, it seemed that mating induce more rapidly than wild types in a view of growth rate. In conclusion, it would be useful to improve mass production with better morphological characteristics through a special mating of L. nuda.

• The Korean Journal of Mycology
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• v.16 no.2
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• pp.79-86
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• 1988

Interspecific fusion products were obtained from fusion of Ganoderma applanatum and Ganoderma luridum. Frequency of fusion was 0.77-1.38%. Fusion products were selected by the comparision of morphology and color of colony. Fusion Products had chracteristics of two parental strains and generally grew faster than the parents. Some fusants were segregated on GCM. Fusion products were confirmed by mycelial morphology and electrophoretics pattern of esterase isozyme from mycelium. Most of fusion products were lack in clamp connection but those fusion products, that were segregated produced mycelium with and without clamp connection. Some of the fusion products produced fruit body on sawdust medium.

• Land and Housing Review
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• v.2 no.4
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• pp.509-516
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• 2011

Compared with the traditional RC system, precast stairs can save construction time, reduce the cost of concrete casting, etc. This paper focuses on an investigation of improved continuous longitudinal joint details for PC stair systems. The performance of the precast concrete stair connections subjected to displacement control cyclic loading is compared with that of the monolithic connection. The developed connection is composed of U-rods and clamp joint metals. This paper proposes precast stair connection with improved structural performance and experimentally evaluates the structural performance of the proposed joints in terms of maximum load, displacement ductiliy, strain, crack and failure modes.

• The Korean Journal of Mycology
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• v.29 no.1
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• pp.72-74
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• 2001

A destructive collar rot of water cress (Oenanthe javanicav) occurred in the commerical farm at Karye-myon, Uiryong-gun, Kyongsangnam-do in 2000. The causal fungus caused stem rot, crown rot, wilt or blight of water cress and the disease incidence in 3 fields ranged from 28.6 to 42.8%. White mycelia spread over tissues near the soil surface or stems, and sclerotia developed on the lesions at late season. The fungus grew well on PDA at $20^{\circ}C$ and the typical clamp connection was formed on its tough white mycelia $4.1{\sim}10.3{\mu}m$. The fungus also formed white mycelia mats and sclerotia at $20^{\circ}C$ on PDA. The sclerotia were globoid and sized $1.0{\sim}6.3{\times}1.0{\sim}5.2mm$ (av. $2.4{\sim}2.2mm$). The causal fungus of collar rot disease was identified as Sclerotium rolfsii on the basis of mycological characteristics and pathogenicity test, This is the first report on the collar rot of water cress caused by Sclerotium rolfsii in Korea.

• Research in Plant Disease
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• v.10 no.1
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• pp.21-24
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• 2004

A destructive stem rot of pepper (Capsicum annuum) was found from the often field sporadically in Jingyemyon, Hadong-gun in July 2002 and vinyl houses in Moonsan-eup, Jinju City in October 2003. The same fungus also caused collar and crown rot and systemic wilt or blight of whole plant. White mycelium spread over stems of infected plants and sclerotia formed on the old lesions and near the soil surface. The fungus showed maximum mycelial growth around 3$0^{\circ}C$. The mycelial color is white and width of hyphae ranges 3.6∼10.2 ${\mu}{\textrm}{m}$, and formed clamp connection. Numerous sclerotia were farmed in artificial media such as PDA at 3$0^{\circ}C$. The shape of sclerotia were sphere and 1.0∼2.1 mm in diameter, The fungus was isolated repeatedly from the infected tissues and the pathogenecity of fungus to pepper (Capsicum annuum) was confirmed, and identified as Sclerotium rolfsii. This is the first report on the stem rot of pepper (Capsicum annuum) caused by Sclerotium rolfsii in Korea.

• The Korean Journal of Mycology
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• v.37 no.1
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• pp.41-48
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• 2009

This study was conducted to investigate optimum cultural conditions for Amanita hemibapha isolated in Korea and its hyphae characteristics. Micrographs shows the presence of clamp connection. A. hemibapha grows as mycelial form(M-phase) 2-4 ${\mu}m$ and yeast-like form(Y-phase) 7-8 ${\mu}m$. The fungal spores were broadly elliptical and papillate, 8-11 ${\times}$ 6-9 ${\mu}m$ in size. The nucleotide sequence analysis of the ITS of nuclear ribosomal DNA from sporocarps and in-vitro-grown mycelium supported the fungal species is Amanita hemibapha. A. hemibapha showed sequence similarity in the ITS rDNA with A. caesarea(97.5) and A. jacksonii(98.5%) which are morphologically similar species to A. hemibapha. The optimal pH and temperature for mycelial growth of A. hemibapha were pH 6.0 and $28^{\circ}C$, respectively. The fungal species showed best growth in SYP and GYS medium. A. hemibapha grew well with mannitol and glucose as carbon sources and peptone as a nitrogen source.

• The Korean Journal of Mycology
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• v.39 no.3
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• pp.254-255
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• 2011

Stem rot symptoms of Euphorbia marginata were occurred in the herb exhibition field at Gyeongsangnam-do Agricultural Research and Extension Services in Korea. The typical symptom was started with watersoaking lesion on the stem then gradually rotted, wilted, and blighted, the severely infected plants were eventually died. The sclerotia of the pathogen were globoid in shape, 1~3mm in size and white to brown in color. The optimum temperature for mycelial growth and sclerotia formation on PDA was $30^{\circ}C$. The hyphal width was 4~9 ${\mu}m$, and the typical clamp connection structures were observed in the hyphae of the fungus grown on PDA. On the basis of mycological characteristics and pathogenicity to host plants, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report of stem rot on E. marginata caused by S. rolfsii in Korea.

• Research in Plant Disease
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• v.16 no.3
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• pp.323-325
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• 2010

The stem rot of sunflower (Helianthus annuus) occurred sporadically in the experimental field of Gyeongsangnam-do Agricultural Research and Extension Services, on September, 2009. The infected plants were wilted and water-soaked brown spots were formed on the stem, than infected stems were mostly died. White mycelial mats were spread over lesions, and then sclerotia were formed on stem and near soil line. The sclerotia were globoid in shape, 1~3 mm in size and white to brown in color. The optimum temperature for mycelial growth and sclerotia formation on PDA was $30^{\circ}C$ and the hyphal width was $4{\sim}8\;{\mu}m$. The typical clamp connections were observed in the hyphae of the pathogenic fungus. On the basis of mycological characteristics and pathogenicity to host plants, this fungus was identified as Sclerotium rolfsii. This is the first report on the stem rot of sunflower by S. rolfsii in Korea.