• Development and Reproduction
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• v.4 no.2
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• pp.175-180
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• 2000

The reproductive cycle of ovoviviparous melania snail, Semisulcospira libeytina libertina was studied in the valley near Naewon Temple in Yangsan, Korea. Water temperature (WT) of the habitat ranged from 1.3$^{\circ}C$ to 22.5$^{\circ}C$ The meat weight rate (MWR) reached the maximum with the beginning of WT increase in March and the minimum in August. Monthly changes in average oocyte diameter showed the maximum (249.6$\pm$2.6 ${\mu}{\textrm}{m}$) in July and the minimum (134.3$\pm$2.8 ${\mu}{\textrm}{m}$) in December S. libertina libertina seemed to be a year-round breeder except for mid-summer and mid-winter. Two main reproductive cycle of the species could be divided into five successive stages: multiplicative (March, October), growing (April and May, November), mature (June and July, December), ovulation (August, January), parturition (September and October, March to May) and resting (September, February) stages in female and multiplicative (March, October), growing (April, November), mature (March to June, December), copulatory (July and August, January), resting (September, February) stages in male.

• Environmental Analysis Health and Toxicology
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• v.22 no.2 s.57
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• pp.119-128
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• 2007

The present study was conducted to find out effect of PFOS on survival, activity, growth and organ structure of the melania snail, Semisulcospira gottschei. Experimental groups were composed of one control condition and four PFOS exposure condition (0.1, 0.5, 1.0 and 5.0 mg/L). After 16 week exposure, survival rate and activity were not significantly influenced at the two lower exposure groups, 0.1 and 0.5 mg/L, but they were significantly reduced in 1.0 and 5.0 mg/L groups. Total weight and meat weight rate (MWR) were reduced in PFOS exposure group in comparison to control group. Also, histological degenerations such as acidification of mucous, necrosis and split of muscular fiber bundle, atrophy of anterior pedal gland were recognized in the foot. Hepatopancreas showed the atrophy and degeneration of the digestive cell, vacuolation of digestive gland and closure of lumen in digestive gland.

• The Journal of the Acoustical Society of Korea
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• v.9 no.3
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• pp.11-23
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• 1990

In order to investigate the acoustical characteristics of the Hae-keum (Korean traditional musical instrument) tone quality, the spectrum and wave form of Hae-keum sounds were analyzed by the FFT Analyzer. The analysis was carried out by the varying of the tension of Hae-keum strings, the positions of bridge and the top plate's thickness of Hae-keum respectively. According to the experiment, the following results are obtained ; the over tone's amplitude nearby the top plate resonance frequency is greater than the fundamental tone's amplitude because the top plate resonance frequency is higher than the fundamental tone's frequency. Tone qualities are better when the bridge is situated in the middle of top plate and the tension of strings is larger. The inharmonicity coefficient of the Hae-keum's second string is 0.049 cents/$n^2$. The brilliance and richness is poor, because we seldom found the over tone over 5kHz and the inharmonicity of the Hae-keum is greater than that of a violin. Also we confirmed that we are able to get the best tone quality in 4.5mm thickness of the Hae-keum's top plate.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.848-851
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• 2010

The essential factor for house cultivation is water management. Water requirement of crop is the most important for the water management. The water requirement of crop is different according to the area as well as climate condition and growth stage. However, the measurement of PET (Potential Evapo-Transpiration) and crop coefficient (Kc) is very difficult especially in house cultivation. Therefore, the PET and Kc of red pepper are estimated based on the lysimeter experiments carried out by the RDA for 11 years about the ratio of house cultivation to wild cultivation. Periodic PET, mean water requirement (MWR) and accumulated water requirement (AWR) of red pepper cultivated in house are evaluated.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3824-3836
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• 2021

Workers' safety from radiological exposure in a 1 ton/day capacity spent resin treatment facility was evaluated according to the operating times and outflow rate due to process related leakages. The conservative annual dose based on the operating times of the workers exceeded the dose limit by at least 7.38E+01 mSv for close work. The realistic dose range was derived as 1.62E+01 mSv-6.60E+01 mSv. The conservative and realistic annual doses for remote workers were 1.33E+01 mSv and 3.00E+00 mSv respectively, which were less than the dose limit. The MWR was identified as the major contributor to worker exposure within the 1 h period required for removal of radioactive materials. The dose considering both internal and external exposures without APF was derived to be 1.92E+01 mSv for conservative evaluation and 4.00E+00 mSv for realistic evaluation. Furthermore, the dose with APF was derived as 7.27E-01 mSv for conservative evaluation and 1.51E-01 mSv for realistic evaluation. Considering the APF for leakage from all parts, the dose range was derived as 1.25E+00 mSv-2.03E+00 mSv for conservative evaluation and 2.61E-01 mSv-4.23E-01 mSv for realistic evaluation. Hence, it was confirmed that radiological safety was secured in the event of a leakage accident.