• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2828-2836
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• 2015

Evaluation items were deducted by based on literature materials to supplement the evaluation system of rock cut-slope in national road. Delphi survey of experts were conducted to review the final evaluation items. As a result of reviewing the significance through stepwise multiple linear regression, all of deducted items were statistically significant because these had lower P-value than 0.05. And It was confirmed that the items were selected appropriately as they had relatively similar levels of the weight. In consideration of CVR and reliability both suggested items and existing items, the exclusible items was selected and new items can complement existing evaluation system were added. Finally 18 rock cut-slope evaluation items was deducted.

• Journal of Surface Science and Engineering
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• v.50 no.4
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• pp.237-243
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• 2017

We demonstrated the thin film deposition of sodium phosphorous oxynitride (NaPON) via RF magnetron sputtering of $Na_3PO_4$, as a solid-state Na-ion conductor similar to lithium phosphorous oxynitride (LiPON), which is a commonly used solid electrolyte. The deposited NaPON thin film was characterized by scanning electron microscopy, X-ray diffractometry, and electrochemical impedance spectroscopy, to investigate the feasibility of the solid-state electrolyte in several different cell configurations. The key properties of a solidstate electrolyte, i.e., ionic conductivity and activation energy, were estimated from the complex non-linear least square fitting of the measured impedance spectra at various temperatures in the range of $27-90^{\circ}C$. The ionic conductivity of the NaPON film was measured to be $8.73{\times}10^{-6}S\;cm^{-1}$ at $27^{\circ}C$, which was comparable to that of the LiPON film. The activation energy was estimated to be 0.164 eV, which was lower than that of the LiPON film (0.672 eV). The obtained values encourage the use of a NaPON thin film in the future as a reasonable solid-state electrolyte.

• Journal of Korean Home Economics Education Association
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• v.15 no.4
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• pp.23-35
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• 2003

The purpose of this research is to analyse the composition of theories and practical activities in clothing and textiles in Technologyㆍ Home economics textbooks in the 7th National Curriculum and find out learning requirement of students in the area. For this research, a survey was conducted using questionnaires with 280 high school students living in Daegu and the rate of response was 78.9%. The results of this study are as follows. 1. After analysing the curriculum of Practical Arts subject in elementary school and Technology´ Home Economics subject in secondary school, we could find out that more emphasis is put on practical activities in elementary school and high school. On the other hand, theories are considered more important in middle school. 2. Students have similar preference both for theories and for practical activities as a way of learning in class and show positive responses to practical activities unless they´re giving too much pressure as a part of performance test. 3. According to their learning requirement. several teaching-learning contents in clothing and textiles in Technology Home economics are selected such as materials,. clothes designs, how to set dressed well, how to make a reasonable purchase on clothes, and the process of manufacturing various clothes, etc. Therefore it would be desirable to provide the students with the learning opportunity to the extent where even the students who haven´t chosen the selected-advanced course can take part in class actively.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.57-64
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• 2004

This is the study for the removal of a toxic heavy metal ions and the recycling of expanded polystyrene wastes. Thus expanded polystyrene wastes collected from the packing materials of TV or chemicals and dissolved by $80wt.\%$ solvent(N, N-Dimethylacrylamide), electrospun in DC 20kV by power supply. Generally, the electrospinning is a process of manufacture to the fibers of nanosize from polymer solution. Manufactured nanofiber mats by electrospinning were sulfonated by cone.-sulphuric acid with $Ag_2S_O_4$ catalysts for the exchange capacity of heavy metal ions and the properties of structure with sulfonated time investigated by FESEM(Feild Emission Scaning Electron Microscope). The ion exchange capacity of light metal$(Na^+)$, Cd(II) and Ni(II), and by a nanofiber mats were 1.94[mmo1/g-dry-mat), 1.72(mmol/g-dry-mat), 1.24(mmol/g-dry-mat), respectively., and water uptake content showed a similar trend with IEC. and The selectivity coefficients $K^M_H$ of Cd(II), Ni((II) ions showed 0.324, 0.228. respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.5
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• pp.701-711
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• 2006

Sewage treatment plants located near to large cities emit extremely higher concentration of odorous materials. This study evaluated flux profiles of ammonia emitted from the water surface of sewage treatment plants using a dynamic flux chamber. Also, an ammonia overall mass transfer coefficient and a mass transfer model was developed in order to estimate fluxes of ammonia using environment parameters and the flux from the sewage treatment plants. The developed mass transfer model was evaluated through a fitness analysis. Comparison modeled flux applying empirical overall mass transfer coefficients of ammonia and measured ammonia flux show a high linearity with 0.977. The flux ratio of 1.282 demonstrated highly statistical fitness, also. Modeled flux using the mass transfer model was compared with measured flux. In result, it indicated that empirical overall mass transfer coefficients were similar to measured flux. The mass transfer model using the empirical overall mass transfer coefficient developed in this study was proved to be an easy and effective method to make accurate and precise predictions for ammonia flux discharged from sewage treatment plants.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.1 s.149
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• pp.106-114
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• 2006

This research aims to identify the recent changes in construction, design, and technical vocabularies between North and South Korea of the Korean woman's top(Jeogori), which is a main part of her traditional costume(Hanbok). After Korea War, Korea was divided into two countries(the division), and there was little communication between the two until 1972(the interexchange). Thus, this study will compare two time periods: 1953-1972 and 1972 to recent times. Hanbok construction books published in both Koreas are evaluated here to see what similarities and differences existed during these two periods. Women in the North continued to wear their traditional costume(renamed the Chosunot in the North) as daily clothing, but women in the South began saving the Hanbok only for parties and ceremonies. As the North Korean government controlled its peoples dress and continued to make changes, the North kept developing new technical vocabularies, but the South continued to use the same terms fur the Hanbok. From the end of the 1990s, the Chosunot had become more and more similar to the Hanbok in colors, shapes, and materials.

• Economic and Environmental Geology
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• v.31 no.5
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• pp.375-388
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• 1998

The purpose of this study is to investigate the ore genesis and occurrence of the Wondong polymetallic mineral deposits. The Pb-Zn, Fe and W-Mo mineralizations are found in skarn zones which formed mainly in or along the fault shear zones with the $N25-40^{\circ}W$ and $N10-50^{\circ}E$ directions, whereas the Cu-Mo mineralization is appeared hydrothermal replacement zone. The skarn minerals consist mainly of garnet and epidote, which were the last alteration phases between pneumatolytic and hydrothermal stages. The mineral paragenesis toward the late stage are as follows: arsenopyrite, scheelite, magnetite, pyrite, pyrrhotite, sphalerite, galena, chalcopyrite and molybdenite. Average ore grades are 0.33 g/t Au, 46.29 g/t Ag, 0.06% Cu, 4.4% Pb, 2.61% Zn and 29.39% Fe in tunnels, and 0.31 % Cu, 0.52% Pb, 6.29% Zn, 29.29% Fe, 0.03% Mo and 0.12% $WO_3$ in drill cores. Fluid inclusion data shows that Type I (liquid-rich), Type II (vapor-rich) and Type III (halite-bearing) inclusions are coexisted and their homogenization temperatures are quite similar. This indicates that boiling conditions have been reached during the mineralization. It is also likely that the ore solutions were evolved through the mixing between magmatic and meteoric waters. Rhyolite and quartz porphyry far the mineralization probably are not responsible of the Wondong polymetallic mineral deposits.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.10 no.6
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• pp.44-52
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• 2007

Recently, oystershell wastes cause serious environmental problem and the need for the researches on the recycling of oystershell have been increased and various methods are already in operation. Field plate bearing tests and numerical analysis were performed to investigate the bearing capacity of oystershell filled geotextile gabion which utilized the waste oystershell at the coastal oyster farm site. The waste oystershell mixed soil specimens were prepared for the laboratory test and field test in terms of varying blending ratio of granite soil and oystershell. Based on the cyclic plate load test results, the spring constant, subgrade modulus of ground, and the reinforcing parameters were determined. The field plate load test results indicate that the bearing capacity of the soil ground with the oystershell mixed ratio of 20% is greater than that of the original ground. Two-dimensional numerical analysis was evaluated the expected deformation in the given conditions. Analysis results show a similar characteristics on bearing capacity with the results of the field plate load test. These findings suggest that the oystershells are very promising construction materials for landfill and earth embankment in coastal area.

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.4
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• pp.329-344
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• 1997

To improve germination and growth of forages of hill pasture seeds of several forages were osmotically primed with polyethylene glycol (PEG) under different PEG concentrations, treatment periods, and temperatures. Seeds were coated with several materials, and tested for germination. The best primed or coated seeds in germination tests were surface sow on hilly area. The results obtained are summarized as follows; 1. Osmotic priming with PEG accelerated germination of forages and reduced time taken for germination. 2. Germinability was best when the seeds of Tama ryegrass or orchardgrass were treated for 6-9 days at 30g PEG1100 ml water, red clover or white clover for 3, or 9 days in 20g PEG1100 ml water at $10^{\circ}C$. 3. Priming seeds of Tama ryegrass or orchardgrass in 30% PEG solution for 6 days, and seeds of red clover or white clover in 20% PEG solution for 6 days at $15^{\circ}C$ were most effective in germination, similar to priming at $10^{\circ}C$ . 4. Priming seeds of Tama ryegrass at 15C, and orchardgrass, red clover, or white clover at $10^{\circ}C$ were effective in germination than priming at other temperatures. 5. Osmotic priming with PEG accelerated germination of forages compared to coated seeds in Petri-dishes, while coated seeds germinated more slowly, but showed better emergence and superior growth to those of primed or intact seeds in the field. 6. Priming seeds increased yield slightly, and coating seeds significantly increased its yield on hilly area.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_1
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• pp.531-539
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• 2020

When injection mold is repeatedly used for mass production, fatigue phenomenon due to cyclic stress may occur. The surface and interior of structure might be damaged due to cyclic stress or strain. The objective of this study was to analyze failure of SCM435 high-tension bolts connecting upper and lower parts of a three-stage injection molding machine. These bolts have to undergo an accurate heat treatment to prevent the formation of chromium carbide and the action of dynamic stresses. Bolts were fractured by cyclic bending stress in the observation of ratchet marks and beach marks. Damaged specimen showed an acicular microstructure. Impurity was observed. Chromium carbide was observed near the crack origin. Both shape parameters of the Vickers hardness were similar. However, the scale parameter of the damaged specimen was about 20% smaller than that of the as-received specimen. Much degradation occurred in the damaged specimen. Bolts should undergo an accurate heat treatment to prevent the formation of chromium carbide. They must prevent the action of dynamic stresses. Bolts need accurate tightening and accuracy of heat treatment and screws need compression residual stress due to peening.