• Journal of the Korean Ceramic Society
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• v.56 no.6
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• pp.534-540
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• 2019

Carbon dioxide emissions involved in global warming are one of the most important issues in the world, and carbon dioxide emissions from the cement industry are about 7% of total carbon dioxide emissions. Thus, reduction in the amount of utilized cement can contribute to a reduction of carbon dioxide emissions. The average life of concrete is 20 ~ 30 years, and if concrete life can be improved by ten years, cement use will be much lower. In this study, we examined the use and effect of fructan from microbes as a method for the densification of the pore structure of cement. The effect of fructan on the hydration reaction and pore distribution, as well as the water absorption of hardened cement mortar were studied. Pores distribution increased in mesopore OPC, and absorption rate was found to decrease with the use of fructan, which has a glue-like and swelling character.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.8
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• pp.742-752
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• 2010

In case of the working machine that using in the loud-noisy workplace, as it generates the loud-noise, it is influencing a physical, mental bad effect to those workers. Accordingly, though the noise countermeasure for the loud-noisy workplace is acutely requiring, until now, those methods that wearing the soundproof-protection tool, or restriction the working hours, and minimize the noise exposure volume, were mainly used. However, such noise countermeasures occur many problem points. On such point of view, using the acoustic simulation technique, let the workers to choose the workplace where suffering many damages due to the noise of working machine, and after grasp the physical property of working machine and indoor acoustic characteristic, this Study has attempted to grasp the reduction degree of noise level at before-improvement?after-improvement, through the sound-absorption measure. Passing through such preceding step, using auralizational technique based on the noise of working machine of before-improvement after-improvement, and by conduct psycho-acoustics evaluation, this study intended to investigate the change degree of subject reaction. As the result of evaluation, it is considering that the noise-reduction countermeasure method for the loud-noisy workplace could be much effective, through the sound-absorption measure.

• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.653-660
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• 2008

The purpose of this study is to analyze the optimal mix design of the sound absorption material that is made from perlite and various binder systems for noise barrier wall. The polymer cement slurry which is made from two types of polymer dispersions, and silicone type inorganic material are used as binder. The test specimens are prepared with various polymer cement ratios, binder ratios, and tested for strengths, freezing and thawing and sound absorption performance by the tube and the reverberation room methods. From the test results, the difference of sound absorption coefficient by the tube method is a little recognized, however, noise reduction coefficient (NRC) of test specimens bound by the polymer cement slurry is in the ranges of 0.48 to 0.51. They are a little higher than those bound by cement only, and are lower values than recommended value of 0.7 by the Ministry of Environment. However, the sound absorption coefficient of test specimens at low frequency range of 250 to 500 Hz by reverberation room method shows very high values as 0.84 to 1.00, and 0.57 to 0.77 at the high frequency. The test specimens with polymer cement slurry binder have a good balance between performance and cost, and have proper properties in strengths, freezing and thawing resistance as sound absorption material for noise barrier wall. It is apparent that the good sound absorption material can be produced according to the optimum mix design that is recommended from this study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.595-600
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• 2012

In this paper, it is investigated the characteristics of DSSC(Dye Sensitized Solar Cell) with cell area(0.25, 1, 2.25 $cm^2$) and dye absorption time(12, 24, 36 h). Thus, we obtain the following results by using the EIS, UV-VIS, I-V measurement. When the cell area increases, the efficiency decreases to 21~32 percent because of the increase about 40~$60{\Omega}$ of internal impedance regardless of dye absorption time. When the absorption time increases up to 24 hours, the efficiency increases to over 40 percent cause of the reduction of internal impedance regardless of cell area. When the dye absorption time becomes 36 hours, the internal impedance increases and at the same time, in the range of 600~700 nm, as the optical absorption reduces. Therefore, the efficiency decreases to 19~31 percent. When it is absorbed the dye for 24 hours in the smallest cell area which is 0.25 $cm^2$, the DSSC has the best efficiency (7.11 %).

• International Journal of Human Ecology
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• v.4 no.1
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• pp.35-44
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• 2003

This study investigated the effects of dietary phyate reduction on the apparent absorption and biochemical parameters of iron status in young Korean women. Fourteen healthy, young women consumed low and high phytate diets for ten days of each experimental period. Duplicate diet samples, a fasting blood sample on day 9, and complete fecal samples for five consecutive days starting from day 5 of each diet period were collected. The iron content of diet and fecal samples were analyzed to calculate apparent absorption. Serum samples were analyzed for iron, ferritin, transferrin receptor and TIBC; transferrin saturation was also calculated. The apparent absorption of iron tended to increase in the low phytate period (32.51%) compared to the high phytate period (17.91%), but the difference was not significant (p=0.06). Serum ferritin decreased and serum transferrin receptor increased significantly during the low phytate diet although the mean values were within the normal range. Serum iron and transferrin saturation did not change significantly. In conclusion, the results indicated that reducing dietary phytate for ten days negatively affected iron nutritional parameters, but it moderately and positively affected apparent iron absorption in young Korean women. Further research on the long-term effects of a low phytate diet with an adequate iron content for vows Korean women is necessary.

• Journal of the East Asian Society of Dietary Life
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• v.3 no.2
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• pp.129-137
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• 1993

This study was attempted to determine the effect of reduction of phytate and phenol compound on the functional properties of sesame protein concentrate. The concentrates were prepared by using dist-water, HCI and butanol. The content of phytate and phenol compound in defatted sesame meal were 4.55% and 3.42% respectively. Considerable amount of phytate was reduced by using HCI, and butanol was effective in removing phenol compounds, Higher bulk density and fat absorption were found in sesame protein concentrate prepared by butanol but higher water absorption was found in the concentrate prepared by dist-water. Also, emulsifying and foaming properties were improved by butanol treatment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.833-838
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• 2005

In this paper, we propose SAR(Specific absorption rate) reduction methods based on surface electric field distribution relation for mobile handsets. Proposed the new method that is able to consider improvement of the SAR from the very beginning step of developing the mobile handsets. Analysis of mobile handset with human body(head) using finite element method(FEM). Results of this method, SAR reduced about $50\;\%$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1241-1246
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• 2009

In this paper, stealth technology, which minimizes detection from the enemy, was analyzed and it was confirmed that Most RCS reduction comes from shaping and in specific parts, by applying RAM. Therefore, we designed and manufactured RAM that absorbs 98% of electromagnetic wave at 94 GHz with 17dB of radar absorption property to minimize RCS at milimeter wave range. As a result, we had 62% reduction in the detection range from the enemy by using developed RAM.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.870-873
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• 2014

Green roof systems has widely been used on rooftop of buildings by considering environmental benefits in aspects of bio-diversity, storm-water runoff as well as noise reduction. To predict noise reduction effect by green roof systems, it is necessary to measure in-situ acoustical properties of the components by devices enabling in-situ measurements. In this study, Micro-flown, which is the state of the arts device to measure in-situ normalized impedance and absorption coefficient has been used to measure acoustical properties of green roof materials according to different water saturation condition in the materials.

• Journal of Biosystems Engineering
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• v.20 no.2
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• pp.127-132
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• 1995

In the first part of this paper, an analysis of the cab noise of a selected agricultural tractor was presented. In this study, using the results of the previous analysis, two passive noise control measures of the sound insulation and absorption were conducted to reduce the noise level inside the cab. These measures of noise control reduced the total noise level by 6.2㏈(A) at the operator position inside the cab. In order to further reduce the cab noise, particularly, of lower frequencies than 630Hz, stiffness and damping of the floor panel should be enforced. It was also suggested that a proper suspension for the cab mounting is necessary to reduce the level of structure-born noises.