• 한국조경학회지
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• 제30권1호
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• pp.61-74
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• 2002

The purpose of this study is to propose vegetation management devices through analyzing the actual vegetation, flora, plant community structure and soil chemical concentrations in Weolmi urban nature park, Incheon. The actual vegetation of Weolmi Park in various areas is composed of urbanization area(2 types, 25.9%), landscape planting area(4 types, 16.1%), grass and marsh area(5 types, 7.6%) and mountain forest areal(14 types, 50.4%). The flora is composed of 295 taxa with 80 families, 253 species, 35 varieties and 7 formas, and among them there are 16 naturalized plant families, 39 species, 3 varieties. In reflection of size, the number of the species seems high but most of the them are under influence of human disturbance. Nine survey plots of plant community structure are classified into two groups. One is the semi-natural plant community(Prunus sargentii-Acer palmatum, Quercus accutissma-Prunus sargentii, Quercus serrata-Quercus accutissma-Prunus sargentii, Prunus sargentii, and Zelkova serrata-Prunus sargentii) that migrated finn the planting forest to the natural forest and the other is planting forest(Pinus koraienssis-Pinus thunbergii-Abies holophylla-Chamaectparis obtusa, Prunus sargentii, Pinus thunbergii-Alnus firma, Zelkova serrata). The average pH is 4.65 which means the soil acidity is quite high. The concentration of K, Ca, Mg and base saturation is very low. It seems that the environmental pollutants from Incheon Port and industrial plants near by survey site and long-distance transport of air pollutants from China made the soil condition worse. On the basis of the results above, six vegetation management devices are suggested: 1) removing the hazard plants(Pueraia thunbergiana and Humulus japonica), 2) natural landscape management of the middle and long term, 3) increasing species diversity, 4) Robinia pseudoacacia management, 5) keeping the naturalized plants from being distributed any further inside the mountain forest, 6) improving soil acidification.

• 한국환경보건학회지
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• 제23권4호
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• pp.97-103
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• 1997

Carbofuran was incubated for four weeks in three differenf types of paddy soil samples at 25$\circ$C. The soil samples prepared in the present study were as follows: control soil, 3% cellulose added soil and 10% cellulose added soil. The degradation rate of carbofuran significantly decreased by the addition of cellulose to soil(p<0.05). The initial pH of soils was 5.0. After incubation for four weeks, the pH of 10% cellulose added soil sample was lower than those of control soil and 3% cellulose added soil. According to increased organic carbon content of the soil, redox potentials of soils decreased. The decreased degradation rate of carbofuran in 10% cellulose added soil was related to the highly negative redox potentials in contrast with the oxidised conditions of control soil and 3% cellulose added soil.

• Interaction and multiscale mechanics
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• 제6권4호
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• pp.339-356
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• 2013

This paper investigates the optimized parameters of Tuned Mass Dampers (TMDs) for vibration control of high-rise structures including Soil Structure Interaction (SSI). The Artificial Bee Colony (ABC) method is employed for optimization. The TMD Mass, damping coefficient and spring stiffness are assumed as the design variables of the controller; and the objective is set as the reduction of both the maximum displacement and acceleration of the building. The time domain analysis based on Newmark method is employed to obtain the displacement, velocity and acceleration of different stories and TMD in response to 6 types of far field earthquakes. The optimized mass, frequency and damping ratio are then formulated for different soil types; and employed for the design of TMD for the 40 and 15 story buildings and 10 different earthquakes, and well results are achieved. This study leads the researchers to the better understanding and designing of TMDs as passive controllers for the mitigation of earthquake oscillations.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.473-480
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• 2006

Liquefaction of soil foundation is one of the major seismic damage types of infrastructures. In this paper, deterministic and probabilistic approaches for the evaluation of liquefaction potential are briefly summarized and the risk assessment method is newly proposed using seismic fragility and seismic hazard curves. Currently the deterministic approach is widely used to evaluate the liquefaction potential in Korea. However, the there are a certain degree of uncertainties in the soil properties such as elastic modulus and resistant capacity, therefore the probabilistic approach is more promising. Two types of probabilistic approach are introduced including (1) failure probability for a given design earthquake and (2) the seismic risk of liquefaction of soil for a given service life. The results from different methods show a similar trend, and the liquefaction potential can be more quantitatively evaluated using risk analysis method.

• Mycobiology
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• 제36권1호
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• pp.1-9
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• 2008

Sixty three species and 5 varieties belonging to 30 fungal genera were collected from 75 soil samples. Cultivated (29 genera and 58 species + 5 var.), desert (22 and 35 + 2 var.) and saline soil (21 and 41 + 1 var.) fungi were recovered on glucose-, cellulose- and 50% sucrose-Czapek's agar at $28^{\circ}C$. The most common genera were Alternaria, Aspergillus, Emerieella, Fusarium, Mycosphaerella, Nectria and Penicillium. The most prevalent species from the three types of soils on the three types of media were Alternaria alternata, Aspergillus flavus, A. fumigatus, A. niger, A. terreus, Emerieella nidulans, Fusarium oxysporum, Myeosphaerella tassiana, Nectria haematococca and Penicillium ehrysogenum. Chaetomium globosum was in the top of fungi in producing endo-$\beta$-1,4-glucanases among the 42 tested isolates obtained from soils on cellulose-Czapek's agar. Maximum production of this enzyme by C. globosum obtained after 6 days of incubation at $30^{\circ}C$ with culture medium containing maltose as a carbon source and ammonium nitrate as a nitrogen source and pH initially adjusted to 6.

• Animal cells and systems
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• 제4권1호
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• pp.57-62
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• 2000

Soil samples were collected in thirteen Manitoba boreal forest sites. Spatial distribution of chytrids from diverse boreal forest microhabitats was investigated by baiting with jack pine pollen. After baiting, the pollen was surveyed for chytrids for 8 ten day period and individual species were counted. Total infestations of pollen by chytrids ranged from 5.8% to 90.2% from various soils. Each site with high infestation was characterized by litter with high needle content while mineral soil or soil with limited organic matter yielded low levels of pollen infestation. Species diversity tended to be higher in soils with higher pollen infestation and lower in soils with lower pollen infestation. Lower diversity was generally observed in mineral soils or soils with a limited organic horizon comprised, in part, of broad leaf litter. Based on coefficients of association and species in common among species across the collection sites, it was possible to relate dominant species assemblages in site groups. These species assemblages in the site groups suggest that the chytrids are distributed by litter and soil types. It can be concluded that the substratum characteristics of litter types and availability of litter may be important in describing chytrid distribution in boreal forest sites.

• 한국농공학회지
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• 제20권1호
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• pp.4599-4613
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• 1978

This study was intended to investigate the effects of bituminous material content of soil-cement mixtures on their durability. For the purpose, unconfined compressive strength test, Freeze-thaw test, and wet-dry test were performed with three types of soil. Each type of soil was mixed with three levels of cement content and each soil-cement mixture was mixed with four levels of bituminous material content. For the unconfined compressive strength test, Freeze-thaw test and wet-dry test, 324, 108, and 108-specimens were prepared respectively. Unconfined compressive strength was measured at age of 7-days, 14-days and 28-days using 108-specimens in each age. The soil-cement loss rate due to freeze-thaw and wet-dry were calculated after 12 cycles of test using 108-specimens in each test. The results are summarized as follows : 1. Optimum moisture content was increased with increase of cement content, but maximum dry density was changed irregulary with increase of the cement content. 2. The unconfined compressive strength was increased with increase of cement content, bituminous material content and curing age. Cement is more effective factor than bituminous material on unconfined compressive strength of soil-cement Mixture. 3. It is estimated as the most economical cement content that the recommended cement content of A.S.T.M. because increasing rate of unconfined compressive strength at age of 28-days was low when cement content is above the recommanded cement content of A.S.T.M. among all types of soil. 4. Although a portion of cement content is substituted for bituminous material, the necessary unconfined compressive strength can be obtained. 5. The soil-cement loss was more influenced by wet-dry than Freeze-thaw 6. The bituminous material is more effective on the decrease of soil-cement loss than increase of unconfined compressive strength 7. The void ratio of soil-cement mixture was changet irregularly with increase of cement content, but that was decreased in proportion to the increase of bituminous material content. 8. The regression equation between the unconfined compressive strength and soil-cement loss rate were obtained as table 7.

• 한국토양비료학회지
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• 제49권5호
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• pp.564-571
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• 2016

As the amount of rice straw collected increases, green manure crops are used to provide the needed organic matter. However, as green manure crops generate methane in the process of decomposition, we tested with different tillage depths in order to reduce the emission. The atmosphere temperature of the chamber was $25{\sim}40^{\circ}C$ during the examination of methane and soil temperature was $2{\sim}10^{\circ}C$ lower than air temperature. The redox potential (Eh) of the soil drastically fell right before irrigated transplanting and showed -300~-400 mV during the cultivating period of rice (7~106 days after transplant). When hairy vetch was incorporated to soil and the field was not irrigated, the generation of methane did not occur from 12 to 4 days before transplanting rice and started after irrigation. Regarding the pattern of methane generation during the cultivation of rice, methane was generated 7 days after transplanting, reached the pinnacle at by 63~74 days after transplanting, rapidly decreased after 86~94 days past transplanting and stopped after 106 days past transplanting. When tested by different soil types, methane emission gradually increased in loam and clay loam during early transplant, whereas it sharply increased in sandy loam. The total amount of methane emitted was highest in sandy loam, followed by loam and clay loam. In all three soil types, methane emission significantly reduced when tillage depth was 20 cm compared to 10 cm. The rice growths and yield were not affected by tillage depth. Therefore, reduction of methane emission could be achieved when application hairy vetch to the soil with tillage depth of 20 cm in paddy soil.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.562-568
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• 1999

The model using homogenization technique based on energy concept for the prediction of the failure criterion of staple fiber mixed soil was developed to increase the practice and the application of staple fiber as a reinforcement for improving soft ground and agrictural structures. Parameters of the model are aspect ration and volumetric ocntnet of fiber, cohesion and internal friction angle of soil, adhesiion intercept of soil and fiber. It is judged that the model developed in this study is applicable to the soil composed of clay, silt and sand mixed by linear types of fiber such as steel bar, steel fiber , natural fiber etc..

• 한국농공학회지
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• 제42권2호
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• pp.86-92
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• 2000

The model using homogenization technique based on energy concept for the prediction of the failure criterion of staple fiber mixed soil was developed to increase the practice and the application of staple fiber as a reinforcement for improving soft ground. Parameters of the model are aspect ratio and volumetric content of fiber, cohesion and internal friction angle of soil, adhesion intercept and interface friction angle of soil and fiber. It is considered that the model developed in this study is applicable to the soil composed of clay, silt and sand mixed by thread types of fiber such as steel bar, steel fiber, natural fiber etc.