• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.6
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• pp.1286-1292
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• 2011

The paper deals with the vibration isolation of a large structure using an experimental technology. In the case of vibration isolation for the vicinity of a subway or a railroad station, most of vibration isolation techniques using isolation materials with high isolation efficiency only, have been applied. Therefore, the quantitative evaluation and design technologies are required for a vibration isolation of large structures. In this study, firstly, vibration characteristics due to train or subway are analyzed. Secondly, the performance of existing vibration isolation materials such as precision isolation material, elastomer is estimated through the experiments. Thirdly, the performance of a tire isolation material and its frame is tested and evaluated. Finally, it is shown that tire isolation materials can be applied to the vibration isolation or vibration reduction of large structures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.415-420
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• 2000

This paper describes a part of the results obtained in the process of the development of thin sound isolation sheets filled mineral compound powder with PVC. The raw materials used are pyrophillite, pottery stone and graphite. The physical properties such as the crystal structures, compositions, and specific gravities, etc. of raw materials are analyzed and discussed from a point of view of sound isolation material. From the analysis of experimental results, the particle size and the additive amount of mineral compound powder for manufacturing sample isolation sheets are decided. The resistant capability against fire of sound isolation sheets including mechanical, thermal and physical properties is tested. The transmission loss measuremenst of sound isolation sheets are performed using two-microphone method in an impedance tube. It is shown that the sound isolation capability of thin sheets has an excellent performance in excess of the object of development.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.537-542
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• 2006

This paper deals with the vibration isolation techniques for a large structure using experimental research. In the case of vibration isolation for the vicinity of a subway or a railroad station, most of vibration isolation techniques using isolation materials with high isolation efficiency only, have been applied. Therefore, the quantitative evaluation and design technologies are required for a vibration isolation of large structures. In this study, firstly, vibration characteristics due to train or subway are analyzed. Secondly, the performance of existing vibration isolation materials such as precision isolation material, elastomer is estimated through the experiments. Thirdly the performance of tire isolation material and its frame is tested and evaluated.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.61-61
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• 1992

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.3
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• pp.105-113
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• 2003

This study developed a practical two-microphone impedance tube method to measure the sound transmission loss of sound isolation materials without the use of an expensive reverberation room or an acoustic intensity probe. In order to evaluate the validation and applicability of the two-microphone impedance tube method, sound transmission losses for several sound isolation materials with different surface density and bending stiffness were measured, and the measured values were compared with the results from the reverberation room method and the theory. From the experimental results, it was found that the accuracy of sound transmission loss obtained by the impedance tube method depends upon the diameter size of the impedance tube (i.e., tested sample size). For sound isolation materials having relatively large bending stiffness such as acryl, wood, and aluminum plates, it was found that the impedance tube method proposed by this study was not valid to measure the sound transmission loss. On the other hand, for sound isolation materials having relatively small bending stiffness such as rubber, polyvinyl, and asphalt sheets, the comparisons of transmission loss between the results from the impedance tube method and the theory showed a good agreement within the range of the frequencies satisfying the normal incidence mass law. Therefore, the two-microphone impedance tube method proposed by this study can be an effective measurement method to evaluate the sound transmission loss for soft sound isolation sheets having relatively small bending stiffness.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.269-274
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• 2004

The aims of this study were to Investigate the floor impact noise isolation performance of floating floor with isolation materials and propose the improvement direction of floor impact noise measurement method and evaluation classes using impact ball. Reduction of light-weight impact sound pressure level can be achieved by the finishing materials, such as vinyl finishing material and wooden flooring with isolation materials. Floor impact noise Isolation material which satisfy the properties of the floor impact noise isolation materials cause resonance in the low frequency band and worsen heavy-weight impact sound pressure level. Heavy-weight impact sound level can be reduced by using noise reduction flooring, ceiling and increase of slab thickness. Strong impact force in low frequency bang below 63Hz of bang machine is not similar to human impact source and causes some problem in evaluating heavy-weight impact noise but heavy-weight impact noise measurement and evolution using impact ball which is very similar to human impact is more reliable than bang machine. Correction value on the background noise and sensitivity of residents should be considered on the floor impact noise evaluation classes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.883-888
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• 2002

This study describes the limit and application of the two-microphone impedance tube method to the sound transmission loss measurement of several sound isolation materials with different physical properties. For the sound isolation materials having small flexural rigidity, it is shown that the two-microphone impedance tube method is validated to practically measure the sound transmission loss. For the sound isolation materials having large flexural rigidity, on the other hand, it is found that the two-microphone impedance tube method is no longer valid to measure the sound transmission loss because the regions of resonance and mass law are moved into the higher frequencies. In addition, in order to accurately measure the sound transmission loss of sound isolation materials, their size should be decided based on the consideration of the effect of acoustic excitation on their vibration response.

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05b
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• pp.67-67
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• 1992

• Korean Journal of Clinical Laboratory Science
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• v.39 no.2
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• pp.76-85
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• 2007

The total number of clinical materials collected from Dec 1, 2005 to Nov 30, 2006 in C. hospital was 63,133. Among these materials, the isolation of Staphylococcus spp. was 5,252 strains. The proportions of Staphylococcus species infection were as follows ; 46.7% in S. aureus, 39.3% in S. epidermidis, 4.7% in S. hominis, 3.8% in S. haemolyticus, 2.9% in S. capitis and 2.5% in others. Seventeen strains of Staphylococcus species were identified with an isolation range of 0.02-46.7%. The isolation ratios of Staphylococcus species were 7.8% (2,134/27,362) in female, 8.7% (3,118/35,807) in male and 8.3% (5,252/63,133) in both. The age-related frequencies of Staphylococcus species were 22.1% in the 60-69 year group, 19.3% in the 70-79 year group and 17.1% in the 50-59 year group. The isolation ratio of the 0-49 year group to the 50-over 80 year group were 1.74 times in female, 1.92 in male and 1.85 in both. The isolation frequency of Staphylococcus spp. was at its highest in April (9.9%) and at its lowest in February (6.8%) according to monthly analysis. According to seasonal variation, the isolation frequencies of Staphylococcus spp. were 27.0% in Summer, 25.9% in Spring, 23.9% in Fall and 23.2% in Winter. The clinical departments showing over 9% isolation rate against Staphylococcus spp. were critical care medicine (12.9%), department of pediatrics (11.6%), department of urology (9.8%) and department of neuro-surgery (9.1%). On the other hand, the lowest number was observed in the department of family medicine. The clinical material showing over 15% isolation rate against Staphylococcus spp. were 32.1% in urine (random urine and catheterized urine), 20.6% in blood and 16.0% in sputum.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.427-431
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• 2017

Recently, complaints of floor noise have been growing up with the rapid increase of the residential buildings. This demands the effective floor noise isolation system. Since the construction of high-rise the residential buildings will be increased even more in future, the noise isolation is a more important technology in the market. In this study, a new floor noise isolation panel (FNIP) was designed and manufactured using waste rubbers. The noise isolation was investigated at both laboratory and field conditions. Light and heavy weight shock wave showed 52 dB and 48 dB in the field test, respectively. The new system could reduce the total floor thickness by 22~42 mm.