• The Korean Journal of Ecology
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• v.21 no.3
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• pp.233-241
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• 1998

In order to test of intermediate disturbance hypothesis that an intermediate level of disturbance maximize biodiversity and to elucidate the effect of disturbance during the early old-field succession, the response of plant community along an experimental disturbance gradient was investigated in a five-year old-field. Response of plant community along an experimental disturbance gradient was connected with light condition because artificial disturbance gradient had been treat by clipping of plants and removing of litter. Artificial disturbance in five-year old-field plant community retarded rate of succession by increasing invasion and performance of the earlier successional species in the initial and middle stage of disturbance treatment. The species richness in the blocks of intermediate disturbance level showed the peak in early and mid-summer. This result did correspond with the prediction of intermediate disturbance hypothesis.

• Animal cells and systems
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• v.8 no.4
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• pp.281-288
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• 2004

The change in relationships between methane production and sulfate reduction was investigated in reclaimed rice field soils at different time points after reclamation of tidal flat in Korea. Sulfate concentrations of soils in the ca. 60-year-old and 26-year-old reclaimed rice fields were much lower than that in a natural tidal flat. During 60 d of anaerobic incubation, total methane production and sulfate consumption of the soil slurries were 7.0 ${\mu}$mol $CH_4$/g and 8.2 ${\mu}$mol $SO_4^{2-}$/g in the 60-year-old rice field, 5.6 ${\mu}$mol $CH_4$/g and 12.7 mmol $SO_4^{2-}$/g in the 26-year-old rice field, and ca. 0 mmol $CH_4$/g and 22.4 ${\mu}$mol $SO_4^{2-}$/g in a natural tidal flat. Relative percent electron flow through sulfate reduction in the 60-year-old rice field was much lower (50.8%) compared with the 26-year-old rice field (69.3%) and the tidal flat (99.9%). The addition of an inhibitor of methanogenesis (2-bromoethanesulfonate) had no effect on sulfate reduction in the soil slurries of the reclaimed rice fields. However, instant stimulation of methane production was achieved with addition of an inhibitor of sulfate reduction (molybdate) in the soil slurries from the 26-year-old reclaimed rice field. The specific inhibitor experiments suggest that the relationship of methanogenesis and sulfate reduction might become mutually exclusive or syntrophic depending on sulfate content in the soil after reclamation. Sulfate, thus sulfate reduction activity of sulfate-reducing bacteria, would be an important environmental factor that inhibits methane production and determines the major pathway of electron and carbon flow in anaerobic carbon mineralization of reclaimed rice field soils.

• Journal of Korean Medicine for Obesity Research
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• v.22 no.1
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• pp.21-29
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• 2022

Objectives: This study aimed to examine the changes in ingredients according to its cultivation method by examining the content of saponin and non-saponin components of ginseng. Methods: Ginseng saponin component analysis was compared and reviewed using the high-performance liquid chromatography method, and acidic polysaccharide component was measured using the carbazole sulfuric acid method. Results: The comparative analysis of ginseng saponin content of 4 and 6 years old fresh ginseng showed the following results. According to the cultivation method, upland field cultivation fresh ginseng showed higher average content of crude saponin than paddy field cultivation fresh ginseng. Whereas, paddy field cultivation fresh ginseng showed higher average content of total saponin than upland field cultivation fresh ginseng. Ginsenoside Rb1 showed higher content of paddy field cultivation fresh ginseng than upland field cultivation fresh ginseng in 6 years old ginseng. However, it showed higher content of upland field cultivation fresh ginseng than paddy field cultivation fresh ginseng in 4 years old ginseng. Additionally, ginsenoside Rg1 showed higher content of paddy field cultivation fresh ginseng than upland field cultivation fresh ginseng in 6 years old ginseng, whereas upland field cultivation fresh ginseng showed higher content of paddy field cultivation fresh ginseng in 4 years old ginseng. The effect on the content of ginseng saponins and acidic polysaccharides according to paddy field and upland field cultivation methods is considered to be small. Conclusions: The paddy field cultivation method, which is more efficient in production cost due to depletion of farmland and long-distance cultivation, is considered to be an economical cultivation method.

• International Journal of Highway Engineering
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• v.18 no.5
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• pp.21-29
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• 2016

PURPOSES : The purpose of this study is to suggest a specific investigation guideline to decide priority of repairing old concrete pavements that pile up substantially. METHODS : In this study, a principle of division of homogeneous sections was proposed to reflect the characteristics of the pavement reasonably in the specific investigation results. In addition, a checklist and guideline of field investigation were suggested for the old concrete pavement sections, which require inspection toward their durability and structural performance. Furthermore, the items of laboratory test necessary to the old concrete pavement were suggested based on the existing laboratory test considering characteristics of the old concrete pavement. The present condition of the old concrete pavement could be analyzed by the test results. RESULTS : A method of division of homogeneous sections suitable for the specific investigation of the old concrete pavement was suggested. The proportions of distress severity of pavement sections were compared by distress type to figure out the present state of the old concrete pavement. Scaling, durability cracking (or alkali-silica reaction), and longitudinal spalling were selected as the most severe distress types. The detailed positions of the sections were also suggested. The checklist of the specific investigation was categorized by field survey and laboratory test, and its evaluation criteria were proposed. The three types of the sections of durability cracking (or alkali-silica reaction), bridge connection, and asphalt overlay were selected as the sections of the field survey. The compressive strength, void structure, and chloride penetration depth were suggested as the items of the laboratory test. CONCLUSIONS : A fundamental level of the guideline was suggested in this study to resolve the problem of old concrete pavement. Appropriate guidelines related to the repair of the old concrete pavement should be provided by performing additional research efforts.

• Journal of the Korean Society of Clothing and Textiles
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• v.24 no.8
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• pp.1266-1275
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• 2000

This study was to research the actual condition of a dropworts working environment and to develope the clothing to reduce the work road. The actual conditions of working environment, working position and clothing were surveyed. Experiments were performed in the chamber and in the field. In the chamber, rectal temperature, 11 points skin temperatures(forehead, chest, abdomen, upperarm, forearm, dorsum manus, palm, thigh, calf, dorsum pedis and pelma), heart rates, microclimates inside clothing on the chest and subjective sensations were measured for comparing between 2 different types o garments. In the field, rectal temperature, abodomen skin temperature, 3 points microclimates inside clothing(chest, back and thigh), heart rates, the volume of EMG and subjective sensations were measured. The results were as follows; 1. There were no significant differences in rectal temperature between a old type protective clothing and a new type both in the chamber and the field. 2. Subjects wearing a old type clothing responded \"a little cold\", \"a little uncomfortable\" and subjects wearing a new type protective clothing responded \"normal\", \"comfortable\" both in the chamber and the field. 3. In the field test results, abodemen skin temperature in a old type clothing was higher and microtemperatures inside clothing of chest, back and thigh in a new type protective clothing were higher. 4. The volume of EMG was lower in the new type protective clothing than in the old one.protective clothing than in the old one.

• The Korean Journal of Ecology
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• v.19 no.4
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• pp.341-351
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• 1996

In order to elucidate the differences in early successional development among similary aged old-fields having different soil nitrogen (N), caused by the land use history before at abandonment, the response of plant community along an experimental nitrogen gradient (control plot (No), plot NI with 5.8g $N/m^2$, plot N2 with 11.7g $N/m^2$ and plot N3 with 23.3g $N/m^2$) was investigated in a five-year-old abandoned field. Although the N content in soil among treatments was similar at the end of the growing season, N concentrations in plant tissue increased with the amount of N supplied. These results suggest that almost all the N contained in N-enriched soil might be absorbed by plants during the growing season after N supply. Vegetation tended to grow vigorously by nitrogen supply, and the standing biomass increased significantly in plots NI and N2 . Species richness of plants, especially of annuals and perennials, was more reduced than the control plot, and the species diversity was also reduced by N supply. The importance value (IV) of species by N supply differed in each species along the position on the successional sere: Artemisia princeps var. orientalis as the dominant species in this old-field decreased slightly; annuals as the earlier successional species decreased clearly along nitrogen gardients; Erigeron annuals as the earlier successional species and as a strong competitor with Artemisia princeps var. orientalis had the highest IV by small N supply; Miscanthus sinensis and Rubus crataegifolius as the later successional species increased by large N supply. These results suggest that old-fields with high soil N might show the structural and functional characteristics of the earlier successional stages, but community composition in those old-fields might be changed more quickly from the sarlier successional species than the later successional species.

• Journal of Ecology and Environment
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• v.29 no.3
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• pp.227-235
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• 2006

Changes of the species diversity and development of vegetation structure during abandoned field succession after shifting cultivation were investigated in Pyoungchang, Gangwon-Do, Korea. The height of top layer tended to increase rapidly during the earlier successional stages and stabilize in the later successional stage. The heights of top layer in the 10, 20, 50 and 80 year old-field were 4, 9, 18 and 18 m, respectively. In this region, thirty five year after abandonment need for the development to the normal forest formed by 4 stratum structure, tree, sub-tree, shrub and herb layer. Among the vegetation values, Ivc showed a tendency to increase logarithmically, and Hcl a tendency to increase linearly during abandoned field succession. Species diversity showed the peak in mid-successional stages ($10{\sim}20$ year old-field) and declined slightly thereafter. Species diversity was correlated closely with the species richness than the evenness. The most woody species established in the earlier stage ($2{\sim}6$ year old-field) and turned over their dominance step by step during succession. These results support the IFC model proposed by Egler (1954).

• Korean Journal of Veterinary Service
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• v.16 no.1
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• pp.70-75
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• 1993

To determine the prevalence of bovine rotavirus Infection in Chungbuk area, fecal specimen were collected from calves nth diarrhea and tested using ELISA. The positive rates were 53.8%(1 to 30days old), 19.0%(31 to 60days old), and 3.2%(over 60days old). Electrophoretic migration patterns of genomic RNA from field isolates were similar to that of NCDV strain, prototype of bovine rotavirus. Bovine rotavirus field isolate showed characteristic morphology of rotavirus particle with 80nm in diameter, using EM.

• Journal of Ginseng Research
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• v.8 no.1
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• pp.57-64
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• 1984

In order to clarify an effect of seedling weight on the growth pattern of ginseng, seedlings ranged from 0.4g plant to 1.8g plant were transplanted, and then the characters of 5- and 6-year-old ginseng were investigated. The characters of root and leaf, such as length and diameter of main root, root weight, leaf area, and leaf dry weight of 5- and 6-year-old ginseng originated from large seedlings were superior as compared with those from small seedlings, and percentage of missing plant was increased with the increase of seedling weight. There were, however, no significant difference in stem length, stem dry weight, number of seeds per plant and number of palmate leaves and leaflets per plant in 5- and 6-year-old ginseng and these characters were not affected by the weight of seedings transplanted. Root field per unit area was higher in seedings of above 0.6g/plant than in small seedlings.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.3
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• pp.35-45
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• 2003

This study was performed to suggest growth status data of the large old trees as the natural monuments of Korea. Field investigation of 70 large old trees as the natural monuments of Korea was carried out in Seoul, Inchon, Kyungki, Chungbuk, Chungnam, Chonbuk, Chonnam. The main field of this study is classified into the growth condition, soil state and management situation. The results of this study are below : The age distribution of the large old trees as the natural monuments of Korea is as follows : above l00years in 5.9%, above 200years in 8.9%, above 300 years in 11.8%, above 400 years in 16.2%, above 500 years in 16.2% and above 600years in 41.1%. Location types of the large old trees as the natural monuments of Korea are found in 11 types; the types are hill side(22.9%), historical monument area(15.7%), field(l4.3%) and building area(12.9%), etc. Also, growth type of the trees is individually placed. In the aspect of soil environment, the acidification of soils has been appearing in all surveyed areas, and the soil of Seoul area has much acidum phosphoricum because of excessive fertilizer. Finally, in management situation. major factors inhibiting growth of the large old trees as the natural monuments of Korea are soil covering of protruded root above ground, soil hardening by human, embankments, small area that has been surrounded fence. Continuous monitoring and accumulation of status data are necessary to preserve the large old trees as the natural monuments of Korea.