• Korean Journal of Food Science and Technology
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• v.24 no.5
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• pp.404-407
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• 1992

This study was conducted to determine the effect of the physical and chemical factors on the absorbance when the chemical component of food was rapidly and effectively analyzed with near infrared reflection spectrophotometer. The absorbance was measured within the wavelength range of 1100 and 2500m and at the various sample temperatures. The absorbance was greatly increased with the rising sample temperature. When the grinding time of samples prolonged, the absorbance was decreased. The absorption peaks occurring in the near infrared spectra of meat, meat protein, pork fat and water were attributed to the overtone and combination vibration of C-H, N-H, O-H or C=O bond within the macromolecules of each sample. The absorbance was lower for meat protein than other meat components. Pork fat was characterized by the ${\cdot}CH_2{\cdot}$ absorption peak at the wavelength of 1700 and 2300 nm and water by the relatively high absorption peak at the wavelength of 1450 and 1930 nm. As a result, the absorbance of near infrared reflection spectrum of meat was affected mainly by fat and water in meat.

• Advances in concrete construction
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• v.11 no.1
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• pp.81-88
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• 2021

Rice Husk Ash (RHA) geopolymer paste activated by sodium aluminate were characterized by X-ray diffractogram (XRD), scanning electron microscope (SEM), energy dispersion X-Ray analysis (EDAX)and fourier transform infrared spectroscopy (FTIR). Five series of RHA geopolymer specimens were prepared by varying the Si/Al ratio as 1.5, 2.0, 2.5, 3.0 and 3.5. The paper focuses on the correlation of microstructure with hardened state parameters like bulk density, apparent porosity, sorptivity, water absorption and compressive strength. XRD analysis peaks indicates quartz, cristobalite and gibbsite for raw RHA and new peaks corresponding to Zeolite A in geopolymer specimens. In general, SEM micrographs show interconnected pores and loosely packed geopolymer matrix except for specimens made with Si/Al of 2.0 which exhibited comparatively better matrix. Incorporation of Al from sodium aluminate were confirmed with the stretching and bending vibration of Si-O-Si and O-Si-O observations from the FTIR analysis of geopolymer specimen. The dense microstructure of SA2.0 correlate into better performance in terms of 28 days maximum compressive strength of 16.96 MPa and minimum for porosity, absorption and sorptivity among the specimens. However, due to the higher water demand to make the paste workable, the value of porosity, absorption and sorptivity were reportedly higher as compared with other geopolymer systems. Correlation regression equations were proposed to validate the interrelation between physical parameters and mechanical strength. RHA geopolymer shows comparatively lower compressive strength as compared to Fly ash geopolymer.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.4
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• pp.291-298
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• 2015

In this study, the reverberation time of apartment living room was measured and distribution of the reverberation time was analyzed. In addition, sound field characteristics of mock-up test room similar with living room and timber structured bedroom was investigated with addition of furniture and sound absorption material. Average reverberation time of unfurnished apartment unit was 1.11 s, and reverberation time in 630 Hz~2000 Hz bands were longer than 1.2 s. It was found that from the field measurement results, reverberation time characteristic of furnished apartment living room was uniform in most of frequency bands. Averaged reverberation time of furnished living room was 0.48 s and the reverberation time of bedroom was 0.44 s. Standardized sound pressure level correction values were calculated from the average reverberation time of furnished and unfurnished apartment units. The correction value of unfurnished living room was −3.4 dB and that of furnished living room was 0.2 dB. Measured reverberation time of furnished and unfurnished apartment units indicated that reference reverberation time; 0.5 s, in KS and ISO standards is reasonable also in Korean residential environment.

• Ocean Systems Engineering
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• v.9 no.4
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• pp.369-390
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• 2019

Herein, we present numerical simulation based model to study the use of a 'Tuned Mass Damper (TMD)' - particularly spring mass systems - to control the displacements at the deck level under seismic and ice loads for an offshore jacket structure. Jacket is a fixed structure and seismic loads can cause it to vibrate in the horizontal directions. These motions can disintegrate the structure and lead to potential failures causing extensive damage including environmental hazards and risking the lives of workers on the jacket. Hence, it is important to control the motion of jacket because of earthquake and ice loads. We analyze an offshore jacket platform with a tuned mass damper under the earthquake and ice loads and explore different locations to place the TMD. Through, selected parametric variations a suitable location for the placement of TMD for the jacket structure is arrived and this implies the design applicability of the present research. The ANSYS^*TM mechanical APDL software has been used for the numerical modeling and analysis of the jacket structure. The dynamic response is obtained under dynamic seismic and ice loadings, and the model is attached with a TMD. Parameters of the TMD are studied based on the 'Principle of Absorption (PoA)' to reduce the displacement of the deck level in the jacket structure. Finally, in our results, the proper mass ratio and damping ratios are obtained for various earthquake and ice loads.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.535-540
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• 2005

In environmental impact assessment, noise impact assessment usually consists of three stages surveying the existing noise levels by measurements, predicting noise levels induced by construction works and predicting noise levels after the completion of project. When predicting noise level in urban area, this method does not consider acoustic phenomena like multi reflection, diffraction and absorption due to complex topographic configuration of building and terrains. For the purpose, a noise mapping tool is utilized to produce a series of noise maps, which are those for the present, for the works of construction and for the future. For accurate noise mapping, acoustical and topographic information is essential. Standard sound power levels and directivities of various construction equipments are required and scheduling of construction processes and locations of the equipments should be provided. In the case of exceeding legal limit, mitigation measures are applied to satisfy the legal limits and subsequent noise map is obtained and checked.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.687-691
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• 2007

It is important to increase the sound proof performance of building for reducing the influence of aircraft noise on the bais of actual survey of existed buildings. The purpose of this study is to propose the basic data for designing sound insulation of residential house. In this study, field measurement of aircraft noise Interior and outside noise level difference were carried out for 7 days in 2 residential houses. As the result, aircraft noise levels showed to be Leq $71.8{\sim}74.5$dB(A), WECPNL $82.2{\sim}83.4$ and indoor noise level were NC-55 ${\sim}63$ over acceptable NC-30 in 2 measured houses. Noise reduction effect showed to be $15.8{\sim}23.1$dB(A) in measured houses, and houses with double window were preferable to those with single window in sound proof performance. The outside sound pressure level for residential house was a little different according to the type of source. In measuring by using aircraft noise it was effected by angle and distance from measuring point, to aircraft, window area, and sound absorption of room, and so on.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.112-120
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• 2008

Today, the use of a vacuum cleaner gave us the higher quality of life than past time, but sometimes made us w1comfortable in the house because of the specific noise that is annoying. So we need to study how sound absorbtion materials affect sound power level and sound quality with sound metrics. In this paper, we will measure and calculate sound power level for vacuum cleaner and analyze characteristics of the noise for 10 Signals according to materials positioned in vacuum cleaner. The multiple regression analysis can estimate the nonlinear characteristics of relation between subjective evaluation and sound metrics. So we will develop sound quality index for vacuum sound.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.7
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• pp.253-260
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• 2001

A Study of interior noise reduction in the magelv train is presented. Tarin speed of interest is low such that aero-dynamic noise is negligible and power supply system is a dominant noise source. Based on the measurements of interior noise and acceleration levels during running and zero speed conditions, dominant noise sources are identified. After spectra characteristics of noise sources are investigated several noise reducing methods are studied such as STL increasement of floor panels. sealing. and absorption treatment It is found that the most important noise sources are VVVF inverter and SLM in running condition, whereas air conditioner and DC/DC converter are dominant in zero speed. Sine the major noise sources are under the floor complete sealing and high STL of the floor panel are shown to be the most crucial factors in noise reduction After sound absorbing material, which is polyurethan foam of 50 mm thickness, is thickness, is attached to the downward side of the floor in addition to sealing treatment, the interior noise is reduced by 3~4 dB.

• Structural Engineering and Mechanics
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• v.65 no.6
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• pp.657-678
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• 2018

Sandwich structures are well known for their use in aircraft, naval and automobile industries due to their high strength resistance with light weight and high energy absorption capability. Sandwich beams with soft core are very common and simple structures that are employed in day to day general use appliances. Modeling and analysis of sandwich structures is not straight forward due to the interactions between core and face sheets. In this paper, formulation of Super Convergent finite elements for analysis of the sandwich beams with soft core based on Euler Bernoulli beam theory are presented. Two elements, Eul4d with 4 degrees of freedom assuming rigid core in transverse direction and Eul10d with 10 degrees of freedom assuming the flexible core were developed are presented. The formulation considers the top, bottom face sheets and core as separate entities and are coupled by beam kinematics. The performance of these elements are validated by results available in the published literature. Number of studies are performed using the formulated elements in static, free vibration and wave propagation analysis involving various boundary and loading conditions. The paper highlights the advantages of the elements developed over the traditional elements for modeling of sandwich beams and, in particular wave propagation analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.33-41
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• 2008

Architectural acoustics design of Namsadang exclusive use theaters should be designed to utilize variously to performance space that can fill flavor and taste of Namsadang performance of the Namsadang six yards. Also, analyze special quality that is sound enemy who follow in sound-absorbing materials fare arrangement of innards that is design material of architectural acoustics laying stress on tradition, use purpose and disappointment size that Namsadang exclusive use theaters seeks on the basis of specific space theme that is experience, disappointment form, seat and passageway Wall and ceiling etc. research and sound and meaning of a character wave motion powerful engineering phenomenon and reduction reverberation loss that is happened from indoor manufacturing thing reduction SCALE model of oval structure research and background of AL composition absorbing material of perforate 25% to heighten acoustic absorptivity of practical use internal organs sound absorption material emir quality sound-absorbing materials insert and layer of air most suitable reverberation time of Namsadang exclusive use theaters that 2.2m volume is $42,218\;m^3$ to become 1.2Sec architectural acoustics design do.