• Journal of Preventive Medicine and Public Health
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• v.31 no.4 s.63
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• pp.616-627
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• 1998

In order to evaluate the cytogenetic hazard among hospital workers potentially exposed to low dose of radiation, the analysis of chromosome aberrations(CA) and sister chromatid exchanges(SCE) in lymphocytes were performed in 79 hospital workers and 79 non-exposed workers. The mean frequency of chromosomal exchange and deletion(respectively, $0.20\times10^{-2}/cell\;and\;0.39\times10^{-2}/cell$) in the exposed group were significantly higher than those$(0.07\times10^{-2}/cell\;and\;0.23\times10^{-2}/cell)$ in control group. The frequency of sister chromatid exchanges was 5.04/cell in the control vs. 6.57/cell in the exposed group. There were also significant differences in the mean frequencies of CA and SCE adjusted for age, sex, smoking, drinking between two groups. There were no evidence of significant increase of CA and SCE according to the department or duration of employment. But the frequency of cells having chromosome aberration was significantly higher in the exposed group than in the control group related to duration of employment. There was no dose-effect relationship between the cumulative doses and the frequency of CA and SCE. But in the case of last 1 yr cumulative dose, there were evidence of significant dose-dependant increase of chromosome type CA and percentage of cells with aberration. The result suggest that there is cytogenetic hazard in risk group like hospital workers handling low dose radiation. And the analysis CA and SCE are useful biological indicators for the exposure of low dose level of radiation.

• Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.75-78
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• 2002

The effects of Coehlodinium polykrikoides on the gill of red sea bream, Pagrus major, were examined to clarify the ichthyotoxic mechanisms of this plankton species. The gill of fish exposed to dense blooms over 3,000 cells/mL for 24 h showed severe epithelial separation: a severe edema was found in the secondary lamellar epithelium and interlamellar regions of primary filament. In addition, lipid peroxidation of gill tissue in Coehlodinium-exposed fish was about 2.5 times higher than that of control. The composition of glycoproteins in the gill mucus of Coehlodinium-exposed fish was also changed. These results suggest that the loss of structural integrity of cell membranes in fish gill may be deeply involved in fish death by C. polykrikoides.

• Journal of Plant Biology
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• v.26 no.3
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• pp.119-130
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• 1983

Algal vegetation in the subtidal zone between a small rock output and the Juckdo Island, eastern coast of Korea was investigated at several selected sites. The objectives of the survey were to descirbe the poorly known macroalgae community in this area and correlate the pattern of distribution as well as the change of zonatin with the environmental conditions. The water movement, light intensity and theinclinatin of substrate are considered as the environmental parameters. The upper and mid subtidal zones in sheltered area with less steep rocky surface are dominated by large brown algae Srgassum confusum; in the exposed area are characterised by species of Costaria costata. In the lower subtidal zone, the difference of vegetaton between the sheltered and the exposed areas is not recognized. At this depth the light intensity is an important ecological factor. Six narrow algal zones occur in the sheltered area, whereas two broad belts occur in the exposed area. the biomass value is 4 times greater in the sheltered area than in the exposed area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.778-784
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• 2017

We investigated the possibility of a bio-monitoring system for predicting toxic dinoflagellates (Genus Alexandrium) by the measuring shell valve movements(SVMs) of Pacific oyster, Crassostrea gigas (Mollusca: Bivalvia) using the Hall element sensor. We then described the SVMs of Pacific oyster exposed to the toxic algae under laboratory conditions. Pacific oyster used for experiment were fed Isochrysis galbana until they stabilized and kept under hunger conditions for three days to prevent the influence of food before the experiment. Pacific oyster were exposed to the toxic dinoflagellate, A. fundyense, and the potentially toxic dinoflagellate, A. affine. When Pacific oyster were exposed to A. fundyense, SVMs increased over 10 times/hr at low cell densities of 20 cells/mL. SVMs increased again at $14.1{\pm}5.7times/hr$ at 500 cells/mL, and $27.9{\pm}11.1times/hr$ at the high cell density of 5,000 cells/mL. However, in the presence of A. affine, SVMs increased at $6.7{\pm}3.9times/hr$ until 300 cells/mL, while they increased greatly to $15.3{\pm}10.8times/hr$ at 1,000 cells/mL. The SVMs of Pacific oyster indicated differences depending on species for toxic dinoflagellates. Therefore, the SVMs of Pacific oyster could be useful for A. fundyense, but would bedifficult to apply for A. affine.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.706-710
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• 2006

To evaluate impacts of the construction noise, Trionyx sinensis, inland fishers aquacultural organism, were exposed to control groups (about 55 dB) and noise groups (80 dB). The survival, growth rate and feeding efficiency of the juvenile Trionyx sinensis were measured at 10, 20 and 30 days intervals (each 9 hours/day). No significant mortality occurred during the experiments, but growth rates (1.7 times) and feeding efficiency (1.83 times) showed significant reduction in time-dependent manner. Also, serum cortisol (6.7 times) and corticosterone levels (1.37 times) in noise groups significantly increased by the noise exposure, compared to the controls, In conclusion, this study may provide the fundamental knowledge on adverse effects Trionyx sinensis and apply to assessments on the impacts of aquaculture industry by construction noise.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.183-188
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• 2005

Two mammalian receptors are reported (MT1A and MT1B). In this experiments, MT1A is expressed at a little enhanced level (about 8 times) in hypothalamus of the 9 hours exposed mice. In other part of the brain, the expression level of the MT1A and MT1B is elevated at nearly same level: 16 times in cerebellum, 128 times in hippocampus and in thalamus, respectively. But MT1B is expressed at very high level (about thousand times) in hypothalamus of the 9 hours exposed mice.

• Advances in concrete construction
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• v.8 no.2
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• pp.139-144
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• 2019

In this study, the mechanical properties of reactive powder concrete (RPC) with a constant cement to silica fume ratio of 4 were investigated. In the experimental program, reactive powder concretes with steel fiber at different ratios were produced. Five productions using quartz sand with a maximum grain size of 0.6 mm were performed. A superplasticizer with a ratio of 3% of the cement was used for all productions. $40{\times}40{\times}160mm$ prismatic specimens were prepared and tested for flexural and compression. The specimens were exposed to two different curing conditions as autoclave and standard curing condition. Autoclave exposure was performed for 3 hours under a pressure of 2 MPa. It was observed that the compressive strength of concrete, along with the flexural strength exposed to autoclave was quite high compared to the strength of concretes subjected to standard curing. The results obtained indicated that the compressive strength, along with the flexural strength of autoclaved concrete increased as the amount of cement used increases. Approximately 15% increase in flexural strength was achieved with a 4% steel fiber addition. The maximum compressive strength that has been reached is over 210 MPa for reactive powder concrete for the same steel fiber ratio and with a cement content of $960kg/m^3$. The relationship between compressive strength and flexural strength of reactive powder concrete exposed to both curing conditions was also identified.

• Korean Journal of Veterinary Research
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• v.34 no.3
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• pp.549-557
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• 1994

This study was done to find the method of the extermination of Fasciola hepatica matacercariae. And the artificial infection was carried out with 30 metacercarae exposed to 5% ammonia water and not-exposed to 5% ammonia water. Serial determinations of live weight, red blood cell, hemoglobin, packed cell volume, and eosinophils were performed in rats at 7 days interval for 16 weeks after infection (WAI). Recovery of worm burden and microscopic findings of livr was performed in rats at 10 WAI. The results in this work were summarized as follows; 1. Fasciola spp metacercariae exposed to 5% ammonia water have lost their ability of infection. 2. In teh exposed group, the mean of worm recovered was 2.25 and the common bile duct was swelling up to 0.71cm in diameter. 3. The value of live weight was different in two groups as the not-exposed group and the exposed group were 321.28, 384.38 at 10 WAI, respectively. 4. In the not-exposed group, at 7 WAI, hemoglobin at 5 WAI and packed cell volume at 7 WAI wre minimally decreased to $5.84{\times}10^{-6}/mm^3$, 11.53g/dl and 43.2%, respectively. But those three values were slowly increased at 10 WAI. Rercent cosinophil was increased to 12.2% at 4 WAI and slightly decreased to 7.9% at 10 WAI. But there are no stastistical singnificance between the exposed group and the normal control group. 5. In histolgical findings in the not-exposed group, the dilated common bile ducts and intrahepatic bile ducts showed distinct hyperplasia of the epithelium. Lymphocytes and eosinophils were infilterated around the bile ducts. The hepatic cells and Kupffer cells showed swollen appearance.

• Journal of Environmental Health Sciences
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• v.21 no.3
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• pp.67-76
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• 1995

The frequencies of chromosome aberrations and sister chromatid-exchanges in peripheral blood lymphocyte of 44 nurses handling anticancer drugs were compared with those in 44 age-match controls. The frequencies of dicentric chrdmosome were $2.4\times 10^{-3}$ in the exposed and $0.5\times 10^{-3}$ in the control. The frequencies of sister cromatid exchanges in the exposed were slightly higher (5.68 SCEs/cell) than those in the control (5.04 SCEs/cell). The frequencies of chromosome aberrations and sister cromatid exchanges were not associated with duration of drug handling and types of anticancer drugs, but associated with use of safety cover.

• Environmental Analysis Health and Toxicology
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• v.20 no.3 s.50
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• pp.223-228
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• 2005

Rockfish Sebastes schlegeli was exposed to fluoranthene, a ubiquitous polycyclic aromatic hydrocarbon, at 1 and 10 $\mu$g/L for 4 weeks followed by depuration period of 8 weeks. Although the fluoranthene in the p]asma reached only 1.8$\~$1.9 times seawater concentration, it was 6.5 $\~$ 15.7 times higher in the liver, spleen and bile indicating efficient accumulation in the lipid -containing body tissues. When the exposed fish were then maintained in clean water, rapid fluoranthene decline occurred in the initial 2 weeks followed by a rather slow phase. This result suggests that fluoranthene accumulates efficiently provided the existence in the culture medium, but the contaminant disappears rapidly once the chemical source is removed. The fluoranthne residue in fish tissues my be a good indifator for relent PAHs exposure.