• Korean Journal of Agricultural Science
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• v.24 no.1
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• pp.21-28
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• 1997

For the investigation of occurrence of insect pests and their natural enemies, total number of 353 controlled agricultural farms were visited and surveyed. In the 73% of total controlled agricultural farms, 52 species insect pests were occurred. Among these pests, the western flower thrip (Frankliniella occidentalis), the two spotted spider mite (Tetranychus urticae), the greenhouse whitefly (Trialeurodes vaporariorum), the cotton aphid (Aphis gossypii) and the green peach aphid (Myzus persicae) were mainly occurred. On the other hand, small numbers of natural enemies were sustained in 40 controlled agricultural farms, which was 11% and 17% of visited farms and pest occurred farms, respectively. For the most part of collected natural enemies, there were included in Braconid, Coccinellid and Anthocorid, as 63, 20 and 8% of them, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.05a
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• pp.11-14
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• 2000

Wastewater sludge and composted food wastes were examined as the alternatives of a landfill cover for soils to eliminate the emission of VOCs. The benefit of these alternatives is in their high sorption capacity, which is 5 to 50 times higher than natural soils. After sorption is finished, biodegradation is an important mechanism in decrease of VOCs concentration. In order to investigate appropriate VOCs degradation condition, biodegradation batch experiment is being conducted with isolated strain X9-c. Both benzene and TCE were degraded only in soil with 12%(water volume/sorbent volumn) water condition. When the water condition varied from 12 to 48% in compost, optimum water conditions of composted food waste was 36%.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.05a
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• pp.37-40
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• 2000

Acoustically enhanced soil flushing method is a newly developed in-situ remediation technique. However, there has not been an analytical method that can be used to evaluate the effectiveness of ultrasonic wave under different conditions. This study was undertaken to investigate the degree of enhancement in contaminant removal due to ultrasonic energy on the soil flushing method. The test conditions included different levels of ultrasonic power and hydraulic gradient. The test soils were Ottawa sand, a fine aggregate, and a natural soil, and the surrogate contaminant was a Crisco Vegetable Oil. The test results showed that sonication could increase contaminant removal significantly. Increasing sonication power increased pollutant removal. The faster the flow is, the smaller the degree of enhancement will be. The pollutants in dense soils are more difficult to be removed than in loose soils.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.3
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• pp.53-64
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• 2001

Bathing beach may be one of the ocean resorts in popular, which peoples can easily access in summer. Three beaches in Jeiu island are surveyed about natural environmental conditions using coastal engineering technique and questionnaire are carried out. Also the satisfaction index on the sand size, wave height, water temperature, transparency and bottom slope is gained very well. The results obtained from this study can be utilized making a new artificial bathing beach in the future.

• 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.

• Journal of Environmental Science International
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• v.21 no.9
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• pp.1087-1095
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• 2012

The investigation was made about distribution and ecological characteristics of host plant for Phellinus linteus at habitats in Gangwon-Do. The habitats of P. linteus are the place where the fog is much generated and there is lots of the moisture. The flora of the vascular plants in P. linteus habitats were consisted of 76 taxa; 62 species, 10 varieties and 4 formas of 62 genera of 40 families. The plants of infiltration type were found 70% around P. linteus habitats. This results shows that the natural environments of P. linteus habitat is very stable condition. The categories of vegetation were classified into two types. The host plant for P. linteus appeared 61.6% from Populus tomentiglandulosa. The first type showed up above the sea about 600m and west exposure region. The second type was investigated around the facing north region of the steep slope-land.

• Ocean and Polar Research
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• v.33 no.3
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• pp.255-263
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• 2011

The aim of this investigation was to evaluate antioxidant activity of crude extracts from the halophyte Vitex rotundifolia, their solvent fractions, and isolated compounds (1-3). Antioxidant capacity was determined by measuring DPPH radical, and authentic $ONOO^-$ and $ONOO^-$ generated from 3- morpholinsydnonimine (SIN-1) in vitro as well as degree of occurrence of intracellular ROS, NO and GSH in mouse macrophage Raw 264.7 cells. From comparative analysis, MeOH extract, n-BuOH, and 85% aq. MeOH solvent fractions showed significant antioxidant effect in DPPH radical and $ONOO^-$ assay systems. Activity-guided purification of n-BuOH and 85% aq. MeOH fractions led to the isolation of flavonoids 1-3. Among them, compound 1 exhibited excellent antioxidant effect in all bioassay systems tested. On the other hand, compounds 2 and 3 revealed potent inhibitory effect against $ONOO^-$ generated from SIN-1, comparable with the positive control penicillamine.

• Smart Structures and Systems
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• v.25 no.6
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• pp.693-705
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• 2020

In the current investigation, large amplitude free vibration behavior of shallow curved pipes (tubes) made of functionally graded materials is investigated. Properties of the tube are distributed across the radius of the tube and are obtained by means of a power law function. It is also assumed that all thermo-mechanical properties are temperature dependent. The governing equations of the tube are obtained using a higher order shear deformation tube theory, where the traction free boundary conditions are satisfied on the top and bottom surfaces of the tube. The von Kármán type of geometrical non-linearity is included into the formulation to consider the large displacements and small strains. Uniform temperature elevation of the tube is also included into the formulation. For the case of tubes which are simply supported in flexure and axially immovable, the governing equations are solved using the two-step perturbation technique. Closed form expressions are provided to obtain the small and large amplitude fundamental natural frequencies of the FGM shallow curved tubes in thermal environment. Numerical results are given to explore the effects of thermal environment, radius ratio, and length to thickness ratio of the tube on the fundamental linear and non-linear frequencies.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.800-809
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• 2007

Current payment methods have many faults which are detrimental to the formation and completion of a project. This includes the use of unfair payment terms, pricing strategies and payment mechanisms between the contracting parties. This resulted in being criticised and remain in doubt, the use of current payment methods to reward good contractors and to distinguish poorly performed construction firms. In order to have an insight into this issue, a structured survey was conducted amongst UK construction practitioners. It was found that traditional pricing methods (i.e. lump sum and unit price), payment methods (i.e. interim valuation) and retention still dominate current practice. The empirical findings show that there are significant differences in the use of pricing and payment methods (when making and receiving payments) in construction. Significant differences also found in the factors affecting the choice of pricing methods when making (and receiving) construction payments. The paper concludes with analysis of the findings and future direction of research in payment systems is also provided.

• Journal of Korea Water Resources Association
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• v.54 no.11
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• pp.985-998
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• 2021

In general, the upstream dam changes downstream flow regime dramatically, i.e., from natural flow regime to hydropeaking flows. This study investigates the impact of the natural flow pattern on downstream fish habitat in a regulated river in Korea using the physical habitat simulation. The study area is a 13.4 km long reach of the Geum-gang River, located downstream from the Yongdam Dam, Korea. A field monitoring revealed that three fish species are dominant, namely Zacco platypus, Coreoleuciscus splendidus, and Opsariichthys bidens, and they account for 70% of the total fish community. Specially, Opsariichthys bidens is an indigenous species in the Geum-gang River. The three fish species are selected as target fish species for the physical habitat simulation. The Nays2D model, a 2D shallow water equation solver, and the HSI (Habitat Suitability Index) model are used for hydraulic and habitat simulations, respectively. To assess the impact of the natural flow pattern, this study uses the annual natural flow regime and hydropeaking flows from the dam. It is found that the natural flow regime increases significantly the Composite Suitability Index (CSI) in the study reach. Then, using the Building Block Approach (BBA), the scenarios for the modifying dam operations are presented in the study reach. Both Scenario 1 and scenario 2 are proposed by using the hydrological method considering both magnitude and duration of the inflow and averaging the inflow over each month, respectively. It is revealed that the natural flow regime embodied in scenario 1 and scenario 2 increases the Weighted Usable Area (WUA) significantly, compared to the hydropeaking flows. In conclusion, the modifying the dam operations by restoring to the natural flow pattern is advantageous to fish community.