• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.323-330
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• 2018

This study investigated effects of absorbent gypsum board in the ceiling on low-frequency heavyweight floor impact sound through sound absorption coefficient and floor impact sound measurement. The sound absorption coefficients were measured with sound absorbent gypsum board, glass wool on gypsum board, and a double panel absorbent gypsum board (absorbent gypsum board + glass wool + absorbent gypsum board). Result showed that the absorbent gypsum board had sound absorption coefficient of 0.1 ~ 0.7 from 200 and 630 Hz octave band. The sound absorption coefficient was increased in all frequency range by adding glass wool. Additional absorbent gypsum board increased sound absorption coefficient up to 250 Hz octave band, but decreased over 250 Hz. Heavyweight floor impact sounds were measured in test building for three materials above, gypsum board, and bare slab. Result showed that glass wool on gypsum board and a double panel absorbent gypsum board reduced by 3 dB ~ 4 dB (single number quantity) heavyweight floor impact sound. Comparing with bare slab condition, floor impact sound reduction was mainly found from 125 Hz to 500 Hz octave band, and the maximum reduction was shown in the 250 Hz octave band.

• Journal of the Korean Wood Science and Technology
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• v.47 no.5
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• pp.644-654
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• 2019

In this study, the gas permeability, sound absorption coefficient, and sound transmission loss of the Paulownia tomentosa wood were estimated using capillary flow porometry, transfer function method, and transfer matrix method, respectively. The longitudinal specific permeability constant of the Paulownia tomentosa wood with a thickness of 20 mm was 0.254 for the control sample and 0.279, 0.314, and 0.452 after being subjected to heat treatments at $100^{\circ}C$, $160^{\circ}C$, and $200^{\circ}C$, respectively. The gas permeability was observed to be slightly increased by the heat treatment. The mean sound absorption coefficients of 20-mm thick Paulownia tomentosa log cross-section for the control sample and after being subjected to heat treatments at $100^{\circ}C$, $160^{\circ}C$, and $200^{\circ}C$ were 0.101, 0.109, 0.096 and 0.106, respectively. Further, the noise reduction coefficients of 20-mm thick Paulownia tomentosa log cross-section of the control sample and after being subjected to heat treatment at temperatures of $100^{\circ}C$, $160^{\circ}C$, and $200^{\circ}C$ were 0.060, 0.067, 0.062 and 0.071, respectively. The mean of sound transmission loss of the 20-mm thick Paulownia tomentosa log cross-section was approximately 36.93 dB. Furthermore, the gas permeability and sound absorption coefficient of the heat-treated Paulownia tomentosa discs slightly increased depending on the heat treatment temperature; however, the rate of increase was insignificant.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.8
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• pp.884-890
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• 2003

In order to reduce the specific absorption rate(SAR) in a human head exposed to electromagnetic fields radiated by a cellular phone, we have analyzed an electromagnetic wave absorber attached to the handset. A manufactured electromagnetic wave absorber was composed of Mn - Zn, which had complex relative permittivity of 7.30-j0.05 and permeability of 2.20-i1.55. The SAR value from the electromagnetic wave absorber attachment was calculated by using the nonuniform finite difference time domain(FDTD) algorithm and measured by phantom model at 835 MHz. The SAR reduction due to the electromagnetic wave absorber are about 18 % at 835 MHz. The V.S.W.R and radiation pattern of antenna are good agreement with the normal antenna. The gain reduction due to the electromagnetic wave absorber are only 0.3 dB at 835 MHz. But the sensitivity of cellular phone generally improves about 1 dB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.615-616
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.717-718
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• 2013

• Applied Chemistry for Engineering
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• v.19 no.6
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• pp.645-651
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• 2008

In this study, the new solubility data at high pressure condition applicable to pre-combustion $CO_2$ capture system were found. Experiments were conducted within the temperature range of $40{\sim}80^{\circ}C$ while increasing the pressure from 0 to 50 bar. The effect of MDEA (N-methyldiethanolamine) concentration was studied by varying the concentration from 30 to 50 wt%. In order to improve the absorption rate of MDEA, piperazine was added in ranging of 5~10 wt% into the MDEA solution as a activator. From this experiment, the equilibrium partial pressure was increased with increasing MDEA concentration in absorbent and reaction temperature. Also absorption rate was increased with increasing the reaction temperature. It was noted that the mixture of piperazine and MDEA aqueous solution showed faster absorption rate by 2.5 times than only the MDEA aqueous solution with 40 wt% cencentration at initial reaction stage and also increased absorption capacity by 16%.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.145-151
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• 2019

In this study, the effects were analyzed by applying the vibration absorption liner into the guide rail bracket as a part of method to reduce the vibration and noise on the high-rise apartment. As the result of vibration absorption liner performance, it was checked that the level of vibration and noise was reduced around 65.49% in the car side and around 90.05% in the counterweight side. Therefore, the vibration absorption effect by the vibration absorption liner of elevator guide rail bracket became fairly good. In case of the vibration absorption liner application, there was an effect on the reduction of 7.26 to 22.22% at hoistway section area, 3,840,000 to 9,780000 KRW at the cost of material and installation by comparing with the damping beam application. Also, in case of the vibration absorption liner application with light weight instead of damping beam with heavy weight, it was thought to become significant effect at preventing the safety from the accidents on installation site.

• The Korean Journal of Food And Nutrition
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• v.14 no.4
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• pp.346-354
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• 2001

Physicochemical properties of dough and bread supplemented with onion (Allium cepa L.) powder were investigated. Farinographic characteristics of dough showed that addition of onion by 2% and 4% increased water absorption, however, as the onion added more the water absorption decreased. Addition of 2% onion delayed time for development of dough a little, while more than 4% onion shortened the development time significant1y. A reduction in stability and an Increase in weakness of dough were observed by addition of onion. Addition of onion powder resulted in a reduction of extendibility and an increase in resistance to extension of dough as measured by extensograph. Amylographic analysis showed that addition of onion increased gelatinization temperature and decreased maximum viscosity. Moisture content, baking loss, height and volume of bread tended to decrease with the addition of onion powder. Lightness of bread crust and crumb decreased as the onion powder added more, while redness and yellowness increased. Bread tilth onion powder had mode free amino acid. especially, Arginine. aspartic acid, glutamic acid and alanine, than control. The addition of onion hardness of bread increased, but springiness decreased as the onion added more. Sensory evaluation of bread indicated that addition of 2% and 4% onion powder enhanced springiness, mouth feeling, appearance, hardness, moistness and overall acceptability.

• Korean journal of food and cookery science
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• v.12 no.1
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• pp.99-107
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• 1996

The cooking characteristics of Hicook with lecithin and GMS as emulsifier were examined for effect on the reduction of oil levels in fried foods. Hicook and soybean oil were used in stir-frying and pan-frying, and in case of Hicook the weight of oil absorbed and spattered during cooking were significantly lower than in case of soybean oil. Next this study attempt to standardize the recipe for preparation of selected Korean foods, especially in regards of the amount of oil used during cooking. The foods studied were all used frequently in Korea, they inculded stir-fried vegetables, stir-fried rice, and pan-fried fish and soybean curd. The results showed that Hicook, even in a half amount, made it possible cooking food with good properties, and calorie content of cooked foods could be lowered considerably. The trained panelists evaluated sensory characteristics of foods, flavor, appearance, and overall acceptability. Sensory qualities of food prepared with Hicook were highly acceptable, and rated better than controls in flavor and overall acceptability. But because stir-fried food was accepted greasy and oily in customarily, the appearance was rated lower than comtrol. In summary, application of hicook offers means of lowering fat levels while keeping sensory quality good. The emulsifier in Hicook is responsible for reduction of oil content and improvement of quality of fried foods.

• Carbon letters
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• v.18
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• pp.24-29
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• 2016

High pollutant-loading capacities (up to 319 times its own weight) are achieved by three-dimensional (3D) macroporous, slightly reduced graphene oxide (srGO) sorbents, which are prepared through ice-templating and consecutive thermal reduction. The reduction of the srGO is readily controlled by heating time under a mild condition (at 1 10⁻² Torr and 200℃). The saturated sorption capacity of the hydrophilic srGO sorbent (thermally reduced for 1 h) could not be improved further even though the samples were reduced for 10 h to achieve the hydrophobic surface. The large meso- and macroporosity of the srGO sorbent, which is achieved by removing the residual water and the hydroxyl groups, is crucial for achieving the enhanced capacity. In particular, a systematic study on absorption parameters indicates that the open porosity of the 3D srGO sorbents significantly contributes to the physical loading of oils and organic solvents on the hydrophilic surface. Therefore, this study provides insight into the absorption behavior of highly macroporous graphene-based macrostructures and hence paves the way to development of promising next-generation sorbents for removal of oils and organic solvent pollutants.