• Korean Journal of Environmental Agriculture
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• v.13 no.3
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• pp.386-395
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• 1994

As a basic research on applying the microbial strains which had been isolated and proved to remove heavy metals, such as Pb, Cd, Zn, and Cu in This laboratory to actual wastewater treatment, optimum condition of the treatment system with addition of single or multiple species of pollutants and microorganisms were investigated at small scale. Concentration of the bacterial inoculum was 3000mg/L and 1500mg/L of MLSS for treatment with single and multiple species, respectively. Removal rates of heavy metals were expressed at HRT’s (Hydraulic Retention Time) of 12, 24, and 48 hr. Removal rates of Pb, Cd, Zn, and Cu after 12 days at HRT of 24hr with addition of single and multiple species were 93%, 90%, 80%, and 39%, and 75%, 90%, 74%, and 48%, respectively. Judging from these results, treatment capability of the isolated strains is excellent. Hence, the microorganisms are expected to be applicable to actual wastewater treatment.

• Journal of Life Science
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• v.12 no.6
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• pp.821-834
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• 2002

In order to measure the inter- and intraspecific genetic divergences within the genus Alexandrium, the variations within the internal transcribed spacer (ITS1 and ITS2) regions and 5.85 ribosomal RNA gene of eight Alexandrium species were examined for 33 strains from diverse geographical locations by direct sequencing. Five isolates of A. tamarense (AT-2, AT-6, AT-10, AT-A and AT-B) from Jinhae Bay, Korea were found to be completely identical to a Japanese strain OFX151-A. The length of the amplified ITSI-5.85-ITS2 region varied from 481 nucleotides (in A. margalefi) to 528 nucleotides (in A. affine CU1-1). ITS1 and ITS2 nucleotide lengths were negatively correlated, whereas a positive correlation was found between their G＋C content. The degree of sequence divergence ranged from 0.3% (1 bp) to a maximum of 53% (305 Up). Pairwise sequence comparisons revealed a small degree of divergence between A. tamarense and A. Pundyense isolates (1.2 - 2.3% ＝ 6-12 bp), but a high degree of divergence between A. tamarense and A. catenella (19.8% ＝ 102 bp), and between A. catenella and A. Pundyense (19.7%). Although most nodes were weakly supported by bootstrap values, some types tend to form independent molecular groups. A. catenella isolates also formed an independent molecular sub-group, with relaticula strong bootstrap values (94% or 85% and 79% or 98%, respectively in PAUP and NJ trees). Interestingly, A. cohorticula and A. frateculus always clustered within the same sub-group, this result being supported by strong bootstrap values. Our results indicate that the ITS regions provide useful informations on hierarchical population genetic structure and a high phylogenetic resolution in intraspecific and interspecific Alexandrium population.

• Journal of Preventive Medicine and Public Health
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• v.32 no.4
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• pp.505-512
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• 1999

Objectives : The purpose of this study was to assess the relationship between job strains and absenteeism from work. Methods : The study design was cross-sectional, and the study subjects consisted of 1,166 workers who were employed in the small-sized industries. A self administered questionnaire was used to measure the general characteristics, job characteristics(job demand, job control), and social support(coworker support, supervisor support) at work. The Job Content Questionnaire(JCQ) was used to assess job demand(2 items) and decision lattitude(10 items). Social support at work (10 items) was measured using JCQ. Sick absence was collected using self-report and were rechecked by the attendance record of their company. Odds ratios and 95% confidence intervals for the association between job strain and sick absence were estimated. The modifying effect of social support was evaluated by stratification. Logistic regression was used to estimate the relationship between job strain and sick absence. Results : In the bivariate analysis, the variables related to sick absence were age, marital status, occupation, job demand. Four distinctly different kinds of level of job strain were generated by the combination of job demand and job control: low strain group, high strain group, active group, and passive group. The crude odds ratio of high job strain was 1.78(95% CI: 1.26-2.53), and those of active group and passive group were 1.33(95% CI: 1.07-1.66) and 1.13 (95% CI: 0.88-1.47), respectively. The odds ratio of high job strain after adjusting for age and occupation were still significant The odds ratio of high job strain in low social support was 5.96(95% CI: 2.45-14.51), but that in high social support was 0.73(95% CI: 0.26-2.01). Conclusions : Job strain was associated with increased risk of absenteeism from work, and social support at work modified the association between job strain and sick absence.

• The Korean Journal of Zoology
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• v.17 no.1
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• pp.5-16
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• 1974

In order to see the single effect and interaction of potassium chloride(KCI) and calcium the chloride ($CaCl_2$) on the development of Drosophila melanogaster, the emergence rates of the five strains of the flies were examined from the media containing 0.0M, 0.5M, 0.1M, 0.2M, of $CaCl_2$ or KCI plus various concentrations of KCI or $CaCl_2$, and the results are presented as follows: 1. The emergence rate of D. melanogaster is not significantly different among strains but strikingly different among concentrations of KCI or $CaCl_2$; the emergence rate decreases as concentration of KCI or $CaCl_2$ increases. 2. The inhibitory effect of $CaCl_2$ on the emergence rates is greater than that of KCI, implying that the resistibility of the flies to KCI is greater than to $CaCl_2$. 3. The addition of small amount of $CaCl_2$ or KCI to KCI or $CaCl_2$ media counteracts the inhibitory effect of KCI or $CaCl_2$, but the addition of a little greater amounts of $CaCl_2$ or KCI to the KCI or $CaCl_2$ media enhance the inhibitory effect of the salts. 4. Thus, there may be some interaction of $K^+$ and $Ca^++$ ions in the inhibitory effect on the development(emergence rates) of Drosophila melanogaster.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.174-179
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• 2007

Seedlot disinfection techniques to control mung bean sprout rot caused by Colletoricum acutatum and C. gloeosporioides were evaluated for commercial production scheme. Soaking seedlots in propolis (100 X) and ethanol (20% for 30 min) appeared promising with control values of 85.5 and 80.8 respectively, but still resulted in up to 20% rot incidence. None of the C. acutatum conidia survived through hot water immersion treatment (HWT) for 10 min at temperatures of 55, 60 and $65^{\circ}C$, whereas the effective range of the dry heat treatment (DHT) was $60-65^{\circ}C$. Tolerance of mung bean seedlot, as estimated by hypocotyl elongation and root growth, was lower for HWT than for DHT. Germination and growth of sprouts were excellent over the range of $55-65^{\circ}C\;at\;5^{\circ}C$ intervals, except for HWT at $65^{\circ}C$ for 5 min. At this marginal condition, heat damage appeared so that approximately 2% of seeds failed to sprout to normal germling and retarded sprouts were less than 5% with coarse wrinkled hypocotyls. These results suggested that DHT would be more feasible to disinfect mung bean seedlots for commercial sprout production. Heat treatment at above ranges was highly effective in eliminating the epiphytic bacterial strains associated with marketed sprout rot samples. HWT of seedlot at 55 and $60^{\circ}C$ for 5 min resulted in successful control of mung bean sprout rot incidence with marketable sprout quality. DHT at 60 and $65^{\circ}C$ for 30 min also gave good results through the small-scale sprouting system. Therefore, we optimized DHT scheme at 60 and $65^{\circ}C$ for 30 min, considering the practical value of seedlot disinfection with high precision and accuracy. This was further proved to be a feasible and reliable method against anthracnose incidence and those bacterial strains associated with marketed sprout rot samples as well, through factory scale mung bean sprout production system.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.143-150
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• 2007

A new virus-like disease of tomato showing chlorotic spots, malformation and necrosis on leaves, and chlorotic blotching, rings, and necrosis on fruits was observed around Sacheon, Gyeongsangnam-do, Korea in 2004. Host range analysis could not differentiate 4 field isolates collected from tomatoes showing different symptoms but identified them as Tomato bushy stunt virus (TBSV). TBSV-tsf2 isolate induced symptoms in indicator plants similar to those caused by the TBSV-C, -S and -Nf. As the isolate could not systemically infect Chenopodium quinoa, the isolate might belong to the previously described TBSV-S isolate. TBSV-tsf2 isolate caused similar cytological alterations that were similar to that generally caused by previously reported TBSV isolates. TBSV-tsf2 isolate, however, could be considered to belong to new strain of TBSV because masses of small electron-dense patches that were not observed from the previously described TBSV. The complete nucleotide sequences of the genomic RNA of 4739 nt excluding non-translated sequences at both termini have been determined and compared to sequences of other TBSV strains. The complete nucleotide sequence identity among TBSV isolates was 98.9% to 99.7%, and to the other tombusviruses ranged from 80.8% to 94.9%. Comparison of the amino acid sequences all five ORFs with those of other TBSV strains shows a similar genomic organization, and high percentage of amino acid sequence homology with TBSV-Nf than TBSV-S isolate. Since the TBSV symptoms were only observed in Sacheon fields where imported seeds from Japan were planted, the TBSV incidence probably caused by the planting contaminated tomato seeds and thus require more through quarantine procedure to prevent settlement of TBSV in Korea. Altogether, these results support that the Korean isolate of TBSV infecting tomato might be new strain.

• Research in Plant Disease
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• v.13 no.1
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• pp.61-65
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• 2007

English ivy (Hedera helix) in Araliaceae family is an evergreen climbing vine. A severe bacterial disease of English ivy was observed and investigated in January 2005. Initial symptoms on the leaves appeared as small water-soaked lesions on the lower surface. As the spots enlarged, the center became brown to brownish black and greenish-brown water-soaked, irregular margins surrounded the center, The spots developed into large irregular blotches, sometimes 5$\sim$10 mm in diameter, then coalesced. Finally, the water-soaked margins raised, dried out, became corky and broke in the center. A bacterial organism, isolated from the advancing margins of the lesions, was tested for its pathogenicity according to the Koch's postulates and biochemical and physiological tests identified the isolated bacterium as a Xanthomonas. The representative Xanthomonas strains (SL4821 and SL4822) isolated from English ivy were compared with a reference strain X. hortorum pv. hederae for fatty acid profiles, metabolic fingerprints and 16s rDNA sequences, showing that all outcomes were indistinguishable between the representative and reference strains. This is the first report of bacterial leaf spot of English ivy in Korea.

• Korean Journal of Microbiology
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• v.31 no.4
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• pp.286-291
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• 1993

The $Km^{r}$ gene and plasmid of natural isolate and genetically modified microorganisms (GMM) rearranged by conjugation in water environments were comparatively analyzed by agarose gel electrophoresis and Southern analysis. The transfer rates of the $Km^{r}$ gene from GMM strains were generally 100 times higher than thosc of natural iso]ate(DKI) under laboratory cnvironments, but their transfer rate was not much different in Moosimcheon River water. The conjugants obtained in LB(Luria-Bertani broth) and FW(filtered river water) water under laboratory conditions showed same number of the plasmids. but the sizes of the plasmids were changed. The $Km^{r}$ gene in the conjugants was found in the same position as the pDKJO] $Km^{r}$ plasmid. In case of the GMM strains as donor. the large plasmids of 180 kb appeared in conjugants obtained in LB and FW water. Especially, the $Km^{r}$ gene in the donor of DKC600 was found to be inserted into chromosome of the conjugant obtained in FW water. However. in the conjugants obtained from DKl and DKB 701 in Moosimcheon River water, the plasmids were rearranged by 4 and 8. respectively, and all of them showed hybridization by the $Km^{r}$ probe. But the small plasmids of the recipient disappeared in the conjugant from DKC600 as donor, and the rearranged plasm ids and chromosome in the conjugants were observed to be hybridized with the $Km^{r}$ probe. Therefore, rearrangement of $Km^{r}$ gene and plasmids by conjugation was found to be afTected diversely by cellular characteristics as well as by environmental factors.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.413-421
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• 2004

In this paper, a structural analysis for the pressurized water reactor(PWR) spent nuclear fuel disposal canister which is deposited under the 500m deep underground is carried out to predict the creep deformation of the canister while the underground water and swelling bentonite pressure are applied on the canister. Usually the creep deformation may be caused due to the Pressure and the high heat applied to the canister even though additional external loads are not applied to the canister. These creep deformations depend on the time. In this paper, oかy the underground water and bentonite swelling Pressure are considered for the creep deformation analysis of the canister, because the heat distribution inside canister due the spent fuel is not simple and depends on time. A proper creep function is adopted for the creep analysis. The creep analysis is carried out during $10^8$ seconds. The creep analysis results show that the creep strains are very small and these strains occur usually in the lid and bottom of the canister not in the cast iron insert. A much smaller strain is found in the cast iron insert. Hence, the creep deformation doesn't affect the structural safety of the canister, and also the creep stress which shows the stress relaxation phenomenon doesn't affect the structural safety of the canister.

• KSBB Journal
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• v.24 no.2
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• pp.149-155
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• 2009

19 strains, which could be identified as Lactobacillus sp. were isolated. The Cucurbita maxima has been known as a traditional healthy food and variable positive effects on the human body were already reported. In this study we tried to develop a production process for a healthy fermented drink with Cucurbita maxima and strains originated from Kimchi. Many kinds of lacctobacci species existed in the fermented food cannot survive in the acidic conditions in the stomach. So we tried to search and select a strain, which can arrive to the small intestine. A species of a Lactobacillus named as C332 was identifed as Lactobacillus plantarum and selected for the fermentation process. With the treatment with artificial gastric juice and artificial bile the survival rate of the cells could be calculated. The physiological characteristics at the variable conditions have been tested. After fermentation process the sensoric tests on the product with panels were tried. The most of the cells could survive in the acidic conditions and falcultive anaerobe. Especially some antibacterial effects aganinst E.coli were also found. With all kinds of the results from our research the fermented Cucurbita maxima drink can be a successful item in the market.