• The Korean Journal of Rheology
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• v.10 no.4
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• pp.256-258
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• 1998

An experimental study was done to improve the processability and optical property of linear low density polyethylene(LLDPE) film. By modifying the molecular structure of LLDPE with electron beam we could get the improved processability and optical property of film. By appropriate dosing of electron beam and a small addition of UV-stabilizer it was possible to produce gel-free film with low haze. The proceassability was also improved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.143-146
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• 1994

In older to investigate the properties of electric conduction in low density polyethylene(LDPE) for power cable, the thickness of specimen was the 30, 100($\mu\textrm{m}$) of LDPE. The experimental condition for conductive properties was measured until the breakdown occurs at temperature ranges from 30 to 110[$^{\circ}C$] and in the electric field of 1 to 5 ${\times}$10$^2$[Mv/m]. As for increase of temperature, the current density of LDPE was increased with constant ratio in low field, but changes with exponential function in high field. The tunnel current of pre-breakdown region is shifted toward low field as much as thermal excitation energy.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.3
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• pp.248-258
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• 1997

The analytical solutions of the Fraunhofer Diffraction(FD) theory and the principle for measurement of the dispersion relation of plasma wave is presented. Especially, the method for measurement of low-frequency wave is discussed. The wavenumbers of the density fluctuations are obtained from the curve fitting between the expremental FD profile and theoretical one for each frequency component. In measurement of the wavenumber of the low -frequency region, the information of the wavenumber is easily obtained from the ratio of the intensity at = 0 to the intensity at =0.5. The millimeter wave FD apparatus was designed to measure low-frequency density fluctuations. The determined wavenumbers are in the range of =0.1~ 1.0cm. Thus, the millimeter wave FD method was shown to be useful for the measurement of low-frequency density fluctuations, which are impossible to be measured by using a convention. Thomson scattering. The obtained dispersion relations will be useful information for plasma waves.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.557-566
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• 2011

The surfactants facilitate the formation of foam bubbles under a proper condition and provide stability of foam bubbles by decreasing the surface tension of solutions and increasing the viscosity of foam surface. However, there have been almost no practical data of foam concrete in this regard so far. This study aims to understand the effects of foaming agents such as anionic synthetic surfactant and anionic natural material surfactant on the low density foamed concrete. From the experiment, the vegetable soap of anionic natural material surfactants showed a higher foaming rate, more open pores, slightly lower compressive strength, and a higher permeability coefficient compared to the vegetable soap of anionic synthetic surfactants. It is believed that the natural material surfactants make not only the surface tension of the solution low but also the viscosity of slurry high.

• Journal of the Korean Vacuum Society
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• v.5 no.1
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• pp.85-92
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• 1996

The external electricla characteristics of helicon wave plasmas were measured over a wide range of RF power and magnetic filed. External parameters. such as antenna voltage , current, phase shift, and interanl parameter, electron density were measured at 7MHz, 1mTorr Ar discharge . The equivalent discharge resistance and reactance, and the power transfer efficiency were calculated through these measurements. There are a helicon mode which produces high density plasma by helicon wave and a lowmode which produces low density plasma by capaictive electric field. In case of the helicon mode, the anternna voltage and current were lower than those of the low-mode. The phase difference between voltage and current decreased suddenly at the transition point from the low-mode to the helicon mode. Equivalent resistance and power efficiency increased and reactance decreased suddenly at the transition point. These results mean that the power transperred to plasma and the nutual coupling between the antenna and plasma increase as the mode changes from the low-mode to the helicon mode.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.612-615
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• 2005

Low cycle fatigue tests are performed on the Incollel 617 that be used fur a hot gas casing. The relation between strain energy density and numbers of cycles to failure is examined in order to predict the low cycle fatigue life of Inconel 617. The life predicted by the strain energy method is found to coincide with experimental data and results obtained from the Coffin-Mansun method. Also the cyclic behavior of Inconel 617 is characterized by cyclic hardening with increasing number of cycle at room temperature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.2986-2999
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• 2019

The uncertainties of the uncertain graph make the traditional definition and algorithms on mining dense graph for certain graph not applicable. The subgraph obtained by maximizing expected density from an uncertain graph always has many low edge-probability data, which makes it low reliable and low expected edge density. Based on the concept of ${\beta}$-subgraph, to overcome the low reliability of the densest subgraph, the concept of optimal ${\beta}$-subgraph is proposed. An efficient greedy algorithm is also developed to find the optimal ${\beta}$-subgraph. Simulation experiments of multiple sets of datasets show that the average edge-possibility of optimal ${\beta}$-subgraph is improved by nearly 40%, and the expected edge density reaches 0.9 on average. The parameter ${\beta}$ is scalable and applicable to multiple scenarios.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.1
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• pp.46-56
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• 2002

The low temperature, low salinity and low density sea water which was originated from the southern part of the Yellow Sea and distributed from the surface to 20 m depth was transported by the northwesterly wind during the period from the middle of March to the beginning of April, 1998 and had an influence on the northern coastal sea area of Cheju Island. Accordingly, this kind of accumulated data may supply the fundamental data for the realtime monitoring of oceanographic conditions and may improve degree of the forecasting accuracy of fishing and oceanographic conditions.

• Korean Journal of Organic Agriculture
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• v.18 no.3
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• pp.387-399
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• 2010

This experiment was conducted to investigate the effects of dietary supplementation of oriental herb extracts (Alpha $Plus^{(R)}$ (AP)+Dried Foxglove Powder (DFP)) on growth performance and proliferation of splenocytes in broiler chicken raised under low or high density stocking conditions. A total of 240 male broiler chicks were randomly divided into four treatment groups with three replicates composed of ten birds in low density stocking groups and thirty birds in high density stocking groups. The four treatment groups were as follows: Cl (low density without AP and DFP); T1 (low density with AP 0.2% and DFP 0.03%); C2 (high density without AP and DFP); T2 (high density with AP 0.2% and DFP 0.03%). The feed intake of the high density stocking group was significantly lower than that of low density stocking groups during overall experimental period (p<0.05). The body weight of high density stocking groups was lower than that of low density stocking groups (p<0.05). The decrease of feed intake and body weight gain in growing stage (7~25day) under the high density stocking condition seems to be recovered in final stage (26~34day). Meanwhile dietary supplementation of AP+DFP in low and high density stocking groups tended to have higher daily body weight gain than control groups. The proliferation of splenocytes in treatment groups was significantly higher than control groups (p<0.05). In conclusion, the result of the present study suggested that the oriental herb extracts (AP+DFP) could be used as an alternative feed additive resources to improve growth performance and immune activity in broiler chickens.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.2
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• pp.42-54
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• 2023

The population is concentrated in the metropolitan areas in Korea, and low-density residential areas are transforming into high density residential areas through redevelopment to meet this demand. However, large-scale redevelopment in a short period of time has a negative impact on the urban climate, such as generating a heat island effect due to the reduction of urban green areas. In this study, the change in surface temperature from 2013 to 2022 in the redevelpment areas of Godeok-dong and Dunchon-dong, Gangdong-gu, Seoul, was analyzed using Landsat 8 satellite images. In the Godeok-dong area, the difference in surface temperature was analyzed for the target redevelopment area, forest area, mixed forest and urban area, and low density residential area. In the Dunchon-dong area, the difference in surface temperature was analyzed for the target redevelopment area, forest area, and low density residential area. The difference in surface temperature was analyzed through multiple regression analysis conducted yearly over the three different stages in redevelopment period. The results from the multiple regression analysis show that in both areas, the land surface temperature of target redevelopment area was higher than that of the forest area and lower than low density residential area. It can be seen that these results occurred because the low-density residential area in Godeok-dong and Dunchon-dong had a lower green area ratio and a higher building-to-land ratio than the target redevelopment area. The results of this study suggest that even if low-density residential areas are transforming into high-density areas, adjusting the management of green areas and building-to-land ratio can contribute to lessen urban heat island effect.