• The Korean Journal of Ecology
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• 제21권5_3호
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• pp.665-673
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• 1998

This study was conducted to clarified the relationship between bird community and forest structure and present the counterplan for protection and management of bird community from February 1993 to July 1995 at deciduous and coniferous forest within Mt. Nam area, Seoul, Korea. DBH distribution has not significant differences in each study site. Deciduous forest had more foliage coverage in all layers than coniferous forest. Total 41 species of birds, which were 16 species of resident, 14 species of summer visitor, 4 species of winter visitor, and 7 species of passage migrant were recrded in two study sites. Leaf use rate of birds was increased the increase of coverage. The number of breeding species and pairs, breeding density, and diversity index were greater in deciduous forest than coniferous forest. The number of species and pairs on bush-nesting and foraging guild were greater than other guilds. And the nuber of species and pairs on hole nesting guild were the fewest in nesting guild. Use rate of artificial nests for improvement of habitat quality was greater in coniferous forest than deciduous forest. Maintenance of bush layer, increase of coverage and leaf layer diversity, supply of artificial nests, management of large trees, and control of natural enemy were necessary for protection and management of bird community in Mt. nam area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.59-62
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• 1999

Inception and propagation of electrical tree and properties of Partial discharge(PD) pulses accompanying with tree as a function of needle tip radius in low density polyethylene were discussed. To study on these characteristics in different tip radius, we used specimens with needle-plane electrode system made of LDPE, observed inception and propagation of electrical tree by optical microscope with computer and investigated the characteristics of the phase resolved PD pulses accompanying with propagation of electrical tree. The PD quantities detected and analysed were PD magnitude, mean phase angle, average discharge, and the statistical characteristics of the PD pulses. As the tip radius ${\gamma}$ increases, tree inception stress E$\sub$i/ converges to constance value. This result suggests that tree inception stress E$\sub$i/ increases due to stress relaxation when the tip radius is small. Branch-type electrical tree was formed When E$\sub$i/ is 640-750[kV/mm]. bush-type electrical tree when E$\sub$i/ is 370∼400[kV/mm], branch-like electrical tree when E$\sub$i/ is 370-400[kV/mm].

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제16권6호
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• pp.619-626
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• 2006

Body-on-frame type vehicle has a set of frame bushes between body and frame for vibration isolation. Such frame bushes are important vibration transmission paths to passenger space for excitations during driving. In order to reduce the vibration level of passenger space, therefore, change of complex stiffness of the frame bushes is more efficient than modification of other parts of the vehicle such as body, frame and suspension. The purpose of this study is to reduce the vibration level for ride comfort by optimization of complex stiffness of frame bushes. In order to do this, a simple finite element vehicle model was constructed and complex stiffness of the frame bushes was set to be design variables. The objective function was defined to reflect frequency dependence of passenger ride comfort. Genetic algorithm and sub-structure synthesis were applied for minimization of the objective function. After optimization level at a position of interest on the car body was reduced by about 43.7 % in RMS value. Causes for optimization results are discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제20권10호
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• pp.907-914
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• 2010

While rubber components are extensively used in automobile vehicle, there are still a lot of difficulties in designing the rubber components applied in complex shapes and preloaded states because of the complicated material properties. In this paper, an efficient experimental method is suggested, which estimates the dynamic stiffness of a rubber component using rubber material test and static stiffness of the bush. And it is verified by comparing with FEM predictions and experimental results. This method is capable of predicting the dynamic stiffness of a rubber bush under various load conditions from minimized test data. Also it estimates dynamic characteristics of a rubber component using rubber material test and FEM calculation.

• Tribology and Lubricants
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• 제38권6호
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• pp.227-234
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• 2022

Recently, the demand for improving energy efficiency has rapidly increased because of the growing concerns over environmental issues. In this work, the tribo-test and simulation for the initial wear and lubrication performance were performed for the piston pin in the small end system of the connecting rod of a marine engine, to obtain useful data for improving the efficiency of marine engine systems. In addition, a diamond-like carbon (DLC) coating was applied to the piston pin to explore feasibility of eliminating the bush used in the system. The initial wear and lubrication characteristics between the uncoated piston pin and bush were compared with that between the DLC-coated piston pin and connecting rod in the tribo-test. The simulation for the wear and lubrication performance according to the wear progression was conducted based on the data obtained from the test. The wear characteristics were quantitatively assessed by the wear depth and wear volume, and the lubrication performance was characterized with the change of pressure and minimum oil film thickness with respect to the crank angle. It was found that the DLC-coated piston pin may provide better initial wear characteristics and lubrication performance. The results of this work may provide fundamental information for marine engines with improved efficiency.

• Korean Journal of Legislative Studies
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• 제15권1호
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• pp.209-235
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• 2009

This articles examines a war of history among American conservatives over the survival strategies of the Republican Party. The traditionalists 'construct' and employ a history originating from Goldwater's libertarianism for criticizing the Bush administration and calling for the restoration of conservative principles of limited, small government. The reformists counter with a history of repeated failures of building "conservatism of the working class."

• Korean Journal of Environment and Ecology
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• 제16권1호
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• pp.22-33
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• 2002

This study was conducted to investigate the effects of fragmentation on the bird community in Seongduck-ri and Hanggum-ri agricultural landscapes of Kangha-myon, Yangpyong-gun, Kyonggido. We analyzed the composition of tree species, forest environmental structures, structures of agricultural landscapes, avifaunas and guild structures. Number and density of tree species ranging from 6 to 10cm in D.B.H. were high in Seongduck-ri, but basal area was high in Hanggum-ri. Coverages of foliage layers under two meters and over 12 meters were high in Hanggum-ri. Meanwhile, Seongduck-ri agricultural landscapes consisted of twelve patches, dominated by Larix leptolepsis and Robinia pseudoacacia Hanggum-ri landscapes was composed of eleven patches, and dominated by Pinus rigida, Castanea crenate, Larix leptolepsis and paddy field. Dominant bird species showed the same order in two study areas, thirty-six species of birds were observed in Hanggum-ri landscapes, but twenty species were in Seongduck-ri landscapes. Number of species and density belonging to hole-, bush-, ground-nesting and water-, bush-, ground-foraging guild were high in Hanggum-ri landscapes. Number of species and density belonging to hole-nesting guild showed the high value in Hanggum-ri landscapes that was not fragmented. It could be attributed to the low human disturbance and relative high density of medium and large trees in D.B.H. Also, number of species and density belonging to bush-, ground- and water- foraging guild showed the high value in Hanggum-ri landscapes that had the high foliage amounts in the foliage layer under two meters. It will be related with the paddy field, dry field and brook, which patches covered the 28.4% of Hanggum-ri landscapes. Therefore, road not only dominate the heterogeneous patch in agricultural landscapes, but also easily cause the human disturbance. Thus, road construction would decrease the natural patch diversity and edge effects that are important for sustaining the diverse avifauna in agricultural landscapes.

• Journal of Bio-Environment Control
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• 제29권4호
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• pp.421-427
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• 2020

In this study, we investigated the effect of nutrient supply periods on the fruit growth and quality of 'Duke' blueberry. The nutrient solution was contained with NO₃-N 4.6, NH₄-N 3.4, PO₄-P 3.3, K 3.0, Ca 4.6, and Mg 2.2 mmol·L^-1, and EC in the nutrient solution was 1.5 ds.m^-1. In 2017 and 2018, an individual blueberry bush was supplied with 8 L of the nutrient solution per week. In 2018, the drainage water quality of growing medium and fruit quality was investigated. The nutrient supply was started from April 01, and stopped at 15 days intervals as follows, 15 days before final harvest, at the final harvest date (June 30), 15 days after final harvest (DAFH), 30 DAFH, 45 DAFH, and 60 DAFH. The content of inorganic components in the growing medium was not significantly different by the stop time of nutrient supply, but the content of phosphorus (P₂O₅) tended to increase with the delay of stop time of nutrient supply. There were no significant differences in the fruit quality characteristics in terms of size, sugar content, and acidity among the different stop time of nutrient supply. The blueberry yield was tended to decrease with the delay of periods of nutrient supply, while the lowest yield of 1.8 kg was recorded when nutrient supply stopped at 45 and 60 DAFH.

• Korean Journal of Agricultural Science
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• 제4권1호
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• pp.61-65
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• 1977

To select some salt tolerant pasture species for grassland establishment on the west coastal saline land in Korea, this work was carried out from March to October in 1976 with 5 pasture seeds mainly were introduced from Australia. On the soil salt content was 0.4%, all seeds germination were failure, but all species were survived on the 0.2% salt content land. The yield of forage were much better from Kikuyu grass and Pearl millet but poor from other species. The Meadow grass could be used for protect soil erosion by lot of tillers. By the result from this experiment, only Kikuyu grass and Pearl millet were possible to use for forage crops. But to continue this work, it is suggested to introduced more effective species such like Saltwater couch, Saltshore ryegrass, Puccinella, Salt bush, Blue buch, Samphire and so on.

• Journal of the Korean Society of Food Science and Nutrition
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• 제16권3호
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• pp.75-84
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• 1987

Lipids in Bush Clover (Lespedza bicolor) seed were extracted with the mix ture of chloro-form-methanol (2 : 1, v/v) and then fractionated into neutral lipids, glycolipids and phospholipids by silicic acid column chromatography. Components and fatty acid composition of each fraction were determined by thin layer and gas chromatographies. The results were summarized as follows. In Bush Clover seed, the contents of neutral lipids, glycolipids and phospholipids were 71.75%, 23.26% and 4.99% respectively. Triglycerides(61.90%) and free fatty acids(22.04%) were the major components among the neutral lipids. Esterified sterols, free sterols, diglycerides and monoglycerides were the minor components. The major components of glycolipids were monogalactosyl diglycerides(38.19%) the others were esterified steryl glycosides, cerebrosides and digalactosyl diglycerides. The major components of the phospholipids were phosphatidyl cholines(36.46%), phosphatidyl inositols(21.52%) and phosphatidyl ethanolamines(17.29%). The major fatty acid of total lipid, neutral lipids and glycolipids were linoleic acid, linolenic acid, oleic acid and palmitic acid. On the other hand, predominate fatty acid of phospholipids were linoleic acid, palmitic acid, linolenic acid and stearic acid.