• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.197-205
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• 2020

With the purpose of designing companion planting of groundcover plants for ornamental uses, this study identified the yearly growth characteristics of nine species of different life forms, analyzed the coverage characteristics of individual plants, and suggested combinations of plants suitable for each life form. Polygonatum odoratum var. pluriflorum, Liriope platyphylla and Hosta capitata, as short-grained plants that can grow to more than 20 cm, tended to grow for 60 days after planting in April and maintain their shape thereafter. Their aerial parts started to wither and enter dormancy after September. Saxifraga stolonifera, Dianthus chinensis and Sedum middendorffianum tended to continuously grow until September after planting in April and their growth declined after September. Lysimachia nummularia, as a creeping plant that grows creeping on the ground, started to show a rapid growth three months after planting. Sedum sarmentosum grew slowly until August and the aerial parts started to wither from September when the temperature decreases. The coverage characteristics of these nine species that grow differently after companion planting were surveyed and the growth of Sedum sarmentosum showed the highest number of companions. It was found that Hosta capitata can be companion planted with Sedum middendorffianum, Saxifraga stolonifera, and Lysimachia nummularia. These results indicate that among different shoot growth types species propagated with their stems creeping on the ground or those that can grow vegetatively with non-rhizome parts are more suitable for companion planting with others than those of which rhizomes branch.

• The Korean Journal of Applied Statistics
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• v.26 no.1
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• pp.151-162
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• 2013

Due to a growing demand for the second-hand product, especially for the expensive one, the warranty and maintenance policies for such products have been studied to improve the product reliability of late. In this paper we study a periodic maintenance model for the second-hand product which is purchased by the customer at the age of $x$. When purchased, the dealer provides a warranty of a fixed length during which the product is maintained periodically to reduce the failure rate of the product and thus, to improve the reliability after each maintenance is served. If a failure occurs between two successive maintenances, only minimal repair is conducted. As for the warranty policy, we adopt free non-renewing repair action on each failure, in addition to the periodic maintenance service during the warranty period. Thus, under the given warranty policy, all the maintenance and repair costs incurred during the warranty period are charged to the dealer. For the proposed periodic maintenance scheme, we formulate a cost model to evaluate the expected total cost charged to the dealer during the warranty period and derive an optimal upgrade level of the failure rate at each maintenance to minimize the expected total warranty cost from the perspective of the dealer. We also present numerical results for an optimal upgrade level based on the proposed methods.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.63-76
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• 2009

On the basis of a Stochastic Frontier Approach (SFA), this paper analyses revenue efficiencies for the same sample of Korean and Japanese railways in the papers which analyze cost efficiencies using a generalized translog functional form. The paper also compares the results of revenue efficiencies with cost efficiencies and evaluates the effects of managerial autonomy and privatization on the firm-specific efficiencies. The results show that the average estimate of revenue inefficiency is 7.02% when the term of inefficiency is assumed to be distributed as a half-normal and 6.98% as a exponential for the total sample. Also, standardized inefficiencies in revenues (7.5%) are greater than those in costs (2.1%). JR East and JR West are found to be most efficient on the revenue side and on the cost side respectively while JNR and JR Kyushu are worst efficient on the both sides. Finally, the correlations between efficiencies in revenues and costs also between efficiencies and privatization are positively correlated. The results suggest that the most independent companies, with increased managerial autonomy via privatization, are the most efficient in both revenues and costs.

• Journal of Veterinary Clinics
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• v.21 no.1
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• pp.45-48
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• 2004

A five months old, female Himalayan cat was referred to the Veterinary Medical Teaching Hospital at Konkuk University, because of suspecting peritoneopericardial diaphragmatic hernia (PPDH). After consecutive examination, the patient was diagnosed as PPDH and hepatic dysfunction. In spite of medical therapy for a month, the serum chemistry profiles for liver enzymes (aspartate transferase: 469 U/L, alanine transferase: above analysis, gamma-glutamyl transferase: above analysis) did not decrease to the normal range. In operation, some of liver was necrotized and was adhesive to diaphragm, these were gently dissected from thoracic structures, and resected. After debriding, the edges of the defect of diaphragm were closed with a simple continuous suture pattern. One month after operation, the cat had normal condition, recovery was uncomplicated, and the serum chemistry profiles for liver enzymes decrease to the normal range.

• 한국해양학회지
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• v.30 no.4
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• pp.237-249
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• 1995

To understand the cross-sectional structures of temperature, salinity and current across the Korea Strait, field measurements were carried out for the period of May 2 to 20, 1994. Using the R/V Tam Yang, detailed CTD profiles and ADCP records were obtained and used to examine the mean and variability field on two time scales (15 days and 25 hours). A sharp coastal front in the middle of the Korea Strait exists across which two different water masses, i.e., warm and saline water in the eastern side and cold and less saline water in the western side are neighboring. We observed highly variable field of T and S apparently caused by the westward movement of warm and saline water mass. Short-term fluctuations of T and S in the middle layer are remarkable and their importance was analysed as the first Eigen mode accounting for more than 50% of total variances. The currents in th Korea Strait are strongly influenced by tidal currents with spring and neap variation whose maximum speed ranges 80-90 and 60-70 cm/s respectively near the central portion of the channel. Strong southward tidal current could even mask the Tsushima Current completely. Results of harmonic analysis show that the magnitudes of semidiurnal, diurnal and mean components of currents are comparable to each other at spring and neap tide conditions. The volume transport across the western channel of the Korea Strait were estimated to be 2.1 Sv at neap tide condition and 3.4 Sv at spring tide condition.

• Research in Plant Disease
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• v.17 no.1
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• pp.78-81
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• 2011

Soft rot caused by Rhizopus oryzae occurred on unshiu orange (Citrus unshiu Marc.) sampled from commercial markets in Jinju, Korea, 2010. The first symptom of soft rot on orange is a water-soaked appearance of the affected tissue. The infected parts later disintegrated into a mushy mass of disorganized cells followed by rapid softening of the diseased tissue. The lesion on orange was rapidly softened and rotted, then became brown or dark brown. Optimum temperature for mycelial growth of the causal fungus on potato dextrose agar was $30^{\circ}C$ and growth was still apparent at $37^{\circ}C$. Sporangiophores were $6{\sim}20\;{\mu}m$ in diameter. Sporangia were globose and $40{\sim}200\;{\mu}m$ in size. The color of sporangia was brownish-grey to blackish-grey at maturity. Sporangiospores were sub-globose, brownish- black streaked and $4{\sim}10\;{\mu}m$ in size. Columella were globose to sub-globose and $85{\sim}120\;{\mu}m$ in size. On the basis of mycological characteristics, pathogenicity test, and the ITS sequence analysis, the causal fungus was identified as Rhizopus oryzae. To our knowledge, this is the first report of soft rot caused by R. oryzae on unshiu orange in Korea.

• Korean Journal of Weed Science
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• v.10 no.4
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• pp.338-343
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• 1990

The intraspecific susceptibility of twelve Echinochloa colona(L.) Link ecotypes to herbicides was studied at three different stages of growth. At germination and post-germination stage, the Batangas ecotype was most susceptible to both butachlor (N-butoxymethyl-2-chloro-2', 6'-diethylacetanilide) and thiobencarb (S-4-dichlorobenzyldiethylthiocarbamate), whereas the Bukidnon ecotype was the most tolerant. The susceptibility of the ecotypes used was not associated with the seed weight and maturity. When the preemergence herbicides were applied at the 2-leaf stage of the ecotypes, the Nueva Ecija ecotype was least susceptible to butachlor at 1 ppm, but it was most susceptible to thiobencarb. The reverse was exhibited by the Cagayan ecotype. Differential susceptibility of the ecotypes to propanil (3', 4'-dichloropropionanilide) as determined by the necrotic length of the third leaf of 20-day-old seedlings was pronounced in the Camarines Sur, Iloilo, and IRRI (red) ecotypes. However, no necrotic tip appeared in the Cagayan and Batangas ecotypes. The differential responses varied with the type and the concentration of the herbicide studied and the growth stage of the ecotypes.

• Journal of the Korean Wood Science and Technology
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• v.28 no.1
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• pp.42-47
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• 2000

This study was designed to investigate the effect of treatment variables on CCA treatment of Japanese red pine (Pinus densiflora), Japanese larch (Larix leptolepis), and ezo spruce (Picea jezoensis) round posts. Variables included were duration of initial vacuum (30, 45, or 60 minutes) and maximum pressure applied (8.5, 10.5, or 14.0 kg/$cm^2$), and maximum pressure was maintained until refusal point was reached. Regardless of wood species, extending the duration of initial vacuum more than 30 minutes did not affect treatability. Increasing pressure did not affect preservative penetration; however, preservative retention was affected by pressure levels, particularly at higher level (14.0 kg/$cm^2$). Preservative penetration depth of Japanese red pine met a minimum requirement specified by Notification of Korean Forestry Administration (No. 1999-8) for hazard class H5 of CCA-treated wood. Penetration of preservative in both Japanese larch and ezo spruce was not deep because of shallow sapwood thickness of these species, so pretreatment such as incising should be considered if these species are treated with preservatives. Although retention in Japanese red pine was not significantly increased even with 14.0 kg/$cm^2$, that of refractory Japanese larch and ezo spruce was significantly increased with the application of 14.0 kg/$cm^2$. Effect of treatment variables on refusal time was unclear; however, it is cleared that the refusal time was shortened with the increase in sapwood thickness.

• Journal of The Korean Society of Grassland and Forage Science
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• v.30 no.4
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• pp.283-290
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• 2010

Guineagrass (Panicum maximum Jacq.) is an important warm-season forage grass as well as biomass crop. It has both sexual and asexual mode of reproduction (apomictic) depending on cultivar. We developed efficient plant regeneration system for an apomictic (cv. Natsukaze) and a non-apomictic (Noh-PL1) guineagrass by optimizing the level of L-proline in the callus induction and that of $AgNO_3$ in plant regeneration medium. Among the L-proline concentrations tested, the best callus induction was achieved by using 2g/L L-proline in both the genotypes. Immature embryos proved to be the best explant source for tissue culture of guineagrass. The highest frequency of shoot regeneration was obtained on MS plant regeneration medium supplemented with 2 mg/L $AgNO_3$. These results provide a foundation for efficient tissue culture and genetic improvement of guineagrass.

• Journal of The Korean Society of Grassland and Forage Science
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• v.31 no.1
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• pp.1-8
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• 2011

Molecular techniques such as genetic transformation are powerful tools that can be used for the genetic modification of warm-season grasses. The P. meyerianum with high regeneration ability was used for establishing an Agrobacterium-mediated transformation system. We investigated various factors affecting Agrobacterium infection by examining GUS gene expression of pCAMBIA1304 vector. Among various concentration of acetosyringone and betaine tested for inoculation and co-cultivation, 10 mg/L acetosyringone and 60 mg/L betaine resulted in the highest transformation frequency in terms of GUS expression. The calli of 4 species of Panicum spp. with excellent tissue culture response were inoculated with Agrobacterium under the optimal infection conditions. The high activity of GUS gene was observed in all species and hygromycin-resistant calli expressing GFP were obtained in P. meyerianum, P. longijubatum, P. stapfianum and guineagrass Noh-PL1. Co-cultivated calli were transferred onto the selection medium containing hygromycin, and the hygromycin resistant calli were selected after 3 months. Hygromycin-resistant plantlets were then successfully regenerated from the calli and grown in a greenhouse. We confirmed stable insertion of hpt gene among the hygromycin-resistant plantlets of P. meyerianum by PCR analysis.