• Tunnel and Underground Space
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• v.20 no.2
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• pp.82-91
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• 2010

Grouting technology is one of the ground improvement methods used in water controlling and reinforcement of rock mass in underground structure construction. It is necessarily required to find out the characteristics of grout flow through discontinuities in a rock mass for an adequate grout design and performance assessment. Laminar flow is not always applicable in simulating a grout flow in a rock mass, since the rock joints usually have apertures at a micro-scale and the flow through these joints is affected by the joint roughness and the velocity profile of the flow changes partially near the roughness. Thus, the influence of joint roughness and aperture on the grout flow in rough rock joint was numerically investigated in this study. The commercial computational fluid dynamics code, FLUENT, was applied for this purpose. The computed results by embedded Herschel-Bulkley model and VOF (volume of fluid) model, which are applicable to simulate grout flow in a narrow rock joint that is filled with air and water, were well compared with that of analytical results and previously published laboratory test for the verification. The injection pressure required to keep constant injection rate of grout was calculated in a variety of Joint Roughness Coefficient (JRC) and aperture conditions, and the effect of joint roughness and aperture on grout flow were quantified.

• Research in Plant Disease
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• v.12 no.2
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• pp.69-74
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• 2006

Basal rot of freesia caused by a Sclerotium sp. occurred at Incheon areas. Incidence of the disease reached up to 45% and averaged 17.0% in the fields. Typical symptoms consisted of sheath dry and leaf blight due to rots on basal leaves. The causal fungus was identified as Sclerotium sp. based on following mycological characteristics. The fungus formed sclerotia on cultural media and plant tissues, but did not produce asexual spores. On cultural medium, aerial mycelia of the fungus changed color from white to clay with cultural age and smelled musty odor. Numerous irregular and elliptical black microsclerotia of the fungus were formed on potato dextrose agar (PDA) after 5 days of incubation at $25^{\circ}C$ and sized $115{\sim}200{\times}95{\sim}150 (av. 145{\sim}126.5){\mu}m$. The fungus grew at $10{\sim}32^{\circ}C$ and $pH 4.0{\sim}8.5$. However, the optimal temperature and pH for mycelial growth of the fungus were $24^{\circ}C$ and 5.5 respectively. The isolate showed present pathogenicity to not only freesia but gladiolus in the pathogenicity test, and the symptoms were similar to those observed in the fields. Basal rot of freesia caused by Sclerotium sp. is firstly reported in Korea.

• Weed & Turfgrass Science
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• v.5 no.4
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• pp.256-259
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• 2016

An obligate plant pathogenic fungus Puccinia zoysiae Dietel, the causal agent of rust disease, which is implicated in the damage of zoysiagrass (Zoysia spp.) in Korea. The fungus is one of the important pathogens, which attacks and colonizes susceptible zoysiagrass. Zoysia rust disease was observed in Jangseong, Hoengseong and Hapcheon in 2014 and 2015, Korea. The typical symptoms of the disease appeared first as small white spots on the leaf and stem of zoysiagrass plants, and turn brownish, dark brown spores revealed on the lesions. Uredospores were light brown in color, ellipsoid or spherical in shape and $22.0{\sim}25.0{\times}15.0{\sim}17.5{\mu}m$ in size. On the basis of the morphological characteristics, the fungus was identified as P. zoysiae. Pathogenicity of the fungus was proved by artificial inoculation on Z. japonica. The rust disease firstly appeared approx. early or middle June and then increased middle of October in Korea. In field, Z. matrella ecotypes were more resistant than Z. japonica ecotypes against the pathogen. Disease response against the pathogen was different among ecotypes of each species, respectively.

• Radiation Oncology Journal
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• v.20 no.3
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• pp.274-282
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• 2002

Purpose : Measurement of transmission dose is useful for in vivo dosimetry. In this study, the algorithm for estimating the transmission dose for open radiation fields was modified for application to partially blocked radiation fields. Materials and Methods : The beam data was measured with a flat solid phantom with various blocked fields. A new correction algorithm for partially blocked radiation field was developed from the measured data. This algorithm was tested in some settings simulating clinical treatment with an irregular field shape. Results : The correction algorithm for the beam block could accurately reflect the effect of the beam block, with an error within ${\pm}1.0\%$, with both square fields and irregularly shaped fields. Conclusion : This algorithm can accurately estimate the transmission dose in most radiation treatment settings, including irregularly shaped field.

• Journal of Plant Biotechnology
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• v.29 no.3
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• pp.193-198
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• 2002

The objective of this study was to determine the effects of phenylacetic acid (PAA) on embryo production in anther and microspore culture of herbaceous peony (Paeonia lactiflora Pall.). The anthers of herbaceous peony were cultured on MS medium with 0 to 100 mg/L PAA according to two-step culture method. The ruptured anthers were transferred onto embryo formation medium without growth regulators. The MS medium with 2 mg/L PAA was effective in enhancing of direct embryogenesis and producing of normal embryo with two cotyledons from the cultured anthers. However, the increase of PAA concentration more than 5 mg/L PAA inhibited the embryo formation and promoted to callus formation from the anthers. The PAA affects significantly on the division of microspore and embryo formation in shed pollen culture and the best result was obtained from a medium supplement with 2 mg/L PAA. The preculture of anther for 10 days on solid medium with 2 mg/L PAA was effective for embryo formation from shed microspore of herbaceous peony.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.4
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• pp.243-252
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• 2002

To develop indicators for soil health evaluation, biological characteristics of native soils from the different parent materials were studied. Survival rate of fluorescent Pseudomonas in soils was the lowest as 0.1% while those of thermophilic Bacillus and alkaliphilic bacteria were over the 90% by the soil drying stress. There was positive relationship between soil microbial biomass and organic carbon exudated from the microbial biomass by the treatment. The average air-drying effect of soils was 39.7% with ranges of 9.7~95.0%. The propagules of mesophilic Bacillus and Gram negative bacteria were increased by the re-wetting of dried soils. Soil pH affected positively to the recovering rate of microbial number. Average recovering rate of microbes was 65.3%, and there was positive relationship between microbial biomass recovery and fluorescent Pseudomonas population.

• Parasites, Hosts and Diseases
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• v.36 no.1
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• pp.7-14
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• 1998

In order to understand the action mechanism of polyhexamethylene biguanide (PHMB) to the cyst of Accnthcnloebc on the morphological basis, the cysts of four corneal isolates of Acanthanoebc were treated with minimal cysticidal concentration (MCC) of PHMB and their ultrastructural changes were examined by transmission electron microscopy. The most striking change of cysts treated with PHMB compared with normal cysts was the shrinkage of intracystic amoebae, which resulted in the separation of the plasma membrane of intracystic amoeba from endocystic wall. Subplasmalemmal lipid droplets became irregularly shaped . In severely damaged cysts, cytoplasm was aggregated and organelles were severely deformed. Cytoplasmic materials were leaked out through the damaged plasma membrane. Most cysts showed aggregation of nuclear chromatin material. Number of mitochondrial cristae was also reduced. Ecto- and endo-cystic walls were relatively well tolerated. Findings in the present study revealed that PHMB affected mainly on plasma membrane, but lesser on organellar membrane of intracystic amoeba. It seemed likely that PHMB might kill cystic forms of Accnthamoebc by similar mechanism in which this environmental biocide can damage the cell wall of Escherichia coli by binding with acidic phospholipids.

• Journal of Plant Biotechnology
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• v.47 no.1
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• pp.78-89
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• 2020

Tomato fruit quality is determined by the contents of various functional metabolites in addition to fruit appearance. To develop tomato cultivars with higher amounts of functional compounds, an efficient quantification method is required to identify the natural variations in the compounds in the tomato germplasm. In this study, we investigated tomato varieties, which included 23 inbred lines and 12 commercial F₁ cultivars, for their contents of seven watersoluble vitamins (vitamin C, vitamins B1, B2, B3, B5, B6, and B9) and five polyphenolic compounds (quercetin, rutin, kaempferol, myricetin, and naringenin chalcone). The results of high performance liquid chromatography and liquid chromatography-mass spectrometry showed that vitamin C and naringenin chalcone were the major water-soluble vitamins and polyphenolic compounds, respectively, and their abundance was highly variable depending on the cultivar. By contrast, the contents of vitamin B1, quercetin, and kaempferol were lowest among the cultivars. With regard to the relationship between metabolic compounds and fruit characteristics, a significant association was found in fruit size, indicating that cherry tomato varieties contain higher amounts of the compounds compared to large fresh-type varieties. However, no direct association was detected in fruit color, except for naringenin chalcone. The results of this study provide new insights on the quantification of metabolic compounds and the selection of breeding materials, which are prerequisites for the development of functional tomato varieties.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.5 no.1
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• pp.39-50
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• 2002

Hepatitis B viral infection which affect about 10% of Korean population manifests asymptomatic carrier, chronic hepatitis and liver cirrhosis and even associates with hepatocellular carcinoma. Clinical manifestations induced by hepatitis B virus vary depending on the degree of immune response by cytotoxic T cells against viral epitope-presenting liver cells. Since hepatitis B virus presents high rate of mutaton that might change the presented epitope and eventually alter immune response, viral mutations, especially in promoters and enhancers, have an important implication in hepatic inflammation and viral replication. To identify mutations related to the hepatic inflammation, we investigated sequence variations of hepatitis B viral promotor regions in the presence or absence of symptoms in hepatitis B carriers. For this, sera from persistently hepatitis B virus-infected mother-child pairs were collected. After PCR amplifiation of all hepatitis B viral promoters (C promoter, S1 promoter, S2/S promoter, X promoter) using serum DNA from each pair, viral promotors were sequenced by automatic sequencer and then sequence data were analyzed by ClustalW. In most cases, the dominant type of maternal virus was transmitted to the child. However, in some children, some new host specific viral variants could be observed in Cp, S1p and S2/Sp. The mutations in C promoter did not seem to be vertically transmitted but arose in new host independently after the wild type had been transmitted. Enhancer I containing X promoter revealed high host specific variations as has been reported before. Two S promoters, S1p and S2/Sp, have shown some point mutations in children, but no deletion mutations were detected as in chronic hepatitis patients in whom deletion mutations are frequently found. In conclusion, the children with the vertically transmitted hepatitis B virus mostly retain the dominant type virus that had been transmitted. However, host specific variants tended to accumulate over time, possibly as clinical symptoms develop.

• Journal of Preventive Medicine and Public Health
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• v.33 no.4
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• pp.449-458
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• 2000

Objectives : To determine the prevalence of prostatitis symptoms in the general population by questionnaire survey and to measure the effect of prostatitis symptoms on quality of life(QOL). Materials & Methods : A cross sectional community-based epidemiologic study was performed on 2,034 men, living in the Seoul metropolitan area using stepwise random sampling. Out of 2,034 interviewees, 1,356 men who were older than 40 and provided sufficient information were selected for this study. The questionnaires were completed by well trained interviewers. Contents of the questionnaires included demographic data, the Prostatitis Symptom Index(PSI), the International Prostate Symptom Score(IPSS), a general health questionnaire section and a sexual health questionnaire section. The PSI was composed of a sum of the scores from three questions about dysuria, penile pain and perineal pain and it ranged 0 to 12. Incidence of prostatitis symptoms was defined by a score of 4 or more and the reference group was defined as consisting of those with a score of 3 or less. The rate of incidence of prostatitis symptoms was assessed according to age and the difference of QOL between the prostatitis symptoms group and the reference group. Results : The overall positive rate of prostatitis symptoms measured by the PSI, in men older than 40, living in the Seoul metropolitan area, was 4.5%(61/1,356), adjusted to 4.8% by the relative proportion of this age group in the general population of the Seoul metropolitan area as compared to Korea and the World. The proportion of the group with prostatitis symptoms assessed by the PSI did not increase with age although the proportion of participants with moderate to severe lower urinary tract symptoms (LUTS) did increase with age. The group with prostatitis symptoms suffered from a much greater incidence of LUTS compared to the reference group (p<0.05). The QOL scores of the IPSS, and the general health and sexual health status of the group with prostatitis symptoms, were worse than those of the reference group.(p<0.05). Conclusions : The positive rate of prostatitis symptoms in men older than 40, living in the Seoul metropolitan area, was 4.8% and it didn't increase with age. The general QOL of the group with prostatitis symptoms was much worse than that of the reference group.