• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.211-220
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• 2005

The concrete structure is being considered for the main engineered barrier of low and intermediate level radwaste disposal facility. Concrete of low permeability can minimize infiltration of water and effectively prevent release of nuclide to ecosystem. But if concrete degrades, structural stability of disposal structure will decrease while permeability increase, resulting in increased possibility of nuclide release due to water infiltration. Therefore disposal concrete structure degradation shall be minimized to maintain capacity of nuclide isolation. The typical causes of concrete structure degradation are sulfide attack, reinforcement corrosion due to chloride attack, leaching of calcium hydroxide, alkali-aggregate reaction and repeated freezing-thawing. The common cause of these degradation processes is infiltration of water or adverse chemicals into concrete. Based on the study of these degradation characteristics and mechanisms of concrete structure, the methodology of design and service life evaluation of concrete structure as an engineered barrier are reviewed to ensure its long-term durability.

• Journal of Korea Soil Environment Society
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• v.1 no.1
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• pp.11-17
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• 1996

Trichloroethylene(TCE) is the organic compound which is used variously at the industrial areas. It contaminates soils and groundwater by leaked storage tank, careless treatment in field and the effluent from waste landfills. This study was carried out to identify adsorptive behavior of TCE by soil. Batch experiments were conducted at different soil-organic matter content and lime treatment to determine Freundlich isothermal adsorption equation constant, k and n, for TCE. Sewage sludge cake was applied to make different soil-organic matter content with the level of Oton/ha(S1), 50ton/ha(S2), 100ton/ha(S3). Lime(calcium hydroxide) was treated with the level of 2ton/ha, 4ton/ha, 6ton/ha, 10ton/ha. Freundlich isothermal adsorption equations obtained from experiment with sewage sludge cake were as follows (on condition that the level of TCE applied to soil ranged from 0.5ng/g soil to 2.5 ng/g soil.) : S1 :x/m = 0.393 $C^2$, S2 : x/m = 0.436 $C^2$, S3 : x/m = 0.636 $C^2$Value of k was increased in higher order of 51, 52, 53 with increased level of sewage sludge cake application. From this results, soil which was applied higher level of sewage sludge cake had a good ability on TCE adsorption. With increased the level of lime application, pH of the soil was increased and the ability of the soil in TCE adsorption was decreased.

• Journal of Biomedical Engineering Research
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• v.25 no.1
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• pp.11-19
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• 2004

Stage 1 sleep provides important information regarding interpretation of nocturnal polysomnography, particularly sleep onset. It is a short transition period from wakeful consciousness to sleep. Lack of prominent sleep events characterizing stage 1 sleep is a major obstacle in automatic sleep stage scoring. In this study, we attempted to utilize simultaneous EEC and EOG processing and analyses to detect stage 1 sleep automatically. Relative powers of the alpha waves and the theta waves were calculated from spectral estimation. Either the relative power of alpha waves less than 50％ or the relative power of theta waves more than 23％ was regarded as stage 1 sleep. SEM (slow eye movement) was defined as the duration of both eye movement ranging from 1.5 to 4 seconds and regarded also as stage 1 sleep. If one of these three criteria was met, the epoch was regarded as stage 1 sleep. Results f ere compared to the manual rating results done by two polysomnography experts. Total of 169 epochs was analyzed. Agreement rate for stage 1 sleep between automatic detection and manual scoring was 79.3％ and Cohen's Kappa was 0.586 (p＜0.01). A significant portion (32％) of automatically detected stage 1 sleep included SEM. Generally, digitally-scored sleep s1aging shows the accuracy up to 70％. Considering potential difficulties in stage 1 sleep scoring, the accuracy of 79.3％ in this study seems to be robust enough. Simultaneous analysis of EOG provides differential value to the present study from previous oneswhich mainly depended on EEG analysis. The issue of close relationship between SEM and stage 1 sleep raised by Kinnariet at. remains to be a valid one in this study.

• Korean Journal of Plant Resources
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• v.15 no.2
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• pp.164-171
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• 2002

Morphological characteristics and growth pattern of 10 Polygonatum collections indigenous to Korea were examined to select the promising medicinal, edible resources and horticultural crops. Plant heights of I0 collections ranged from 15 to 102cm. Stem type was ascending or erect, and node numbers per a stem was 6.2 to 23.2. Phyllotaxis type was alternate or verticillate, and leaf shape was elliptical or linear. Leave numbers per a stem was 5.2 to 63.4, and bract types were classified into bracteate and nonbracteate. Flowers bloomed from May 7 to May 30, and flowering period was 5 to 13 days. Inflorescence types were classified into racemose, corymbose, and umbellate. Flower numbers per a stem was 1.5 to 125.2, and flower length was 13.1 to 30.2㎜. Perianth shapes were classified into tubular, constrict and urceolate. Surface colors of rhizome were pale yellow, pale brown, brown, and dark brown. As a result of this experiment, P. sibiricum, P. odoratum var. pluriflorum and P. odoratum var. thunbergii were thought to be useful as the medicinal and edible resources plants. On the other hand, P. odoratum var. pluriflorum 'Variegata', and P. odoratum var. maximowiczii, P. lasianthum. P. involucratum, P. desoulavyi, P. humile, and P. inflatum were thought to be useful as horticultural plants.