• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.2
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• pp.263-271
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• 2008

Compressor radiated noise is one of the dominant noise for the outdoor unit of the air conditioner. Therefore, air conditioner makers are trying to reduce it continuously. Even though noise absorption and isolation technology are one of the important parts for reducing the noise from the compressor, it is usually treated to the substitute technology when the noise from the compressor is very difficult to reduce by the compressor noise control only. In this paper, we focus on the property of the sound insulation for the cabinet and measure it applying the theory of the sound transmission loss and insertion loss of the simple enclosure. The insertion loss is evaluated by the experiments according to the thickness and the aperture of the partition in the cabinet.

• Fire Science and Engineering
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• v.21 no.3
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• pp.91-96
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• 2007

Performance analysis of the butterfly valve in water fire extinguishing has been carried out. Performance analysis of the butterfly valve are investigated for torque characteristics, pressure loss and cavitations. The torque characteristics of disc are corrected for the angles of attack of valve disc by theoretical torque equation, and correction equation is added. The pressure loss coefficient on opening angle of valve has been formulated by applying the Carnot's equations. The torque characteristics, pressure loss and cavitations of the butterfly valve are analyzed for the ratio of disc thickness to the valve diameter. Cavitations are analyzed from the pressure loss coefficient of valve. The analysis of pressure loss and cavitation has been carried out change of the thickness ratio on opening angle of valve. These analysis data are utilize to necessary engineering data to develope of the butterfly valve.

• Journal of Magnetics
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• v.13 no.3
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• pp.92-96
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• 2008

There are few reports of high frequency loss behavior in the near-field for magnetic films with semiconducting properties, even though semiconducting magnetic materials, such as soft magnetic amorphous alloys and nanocrystalline thin films, have been demonstrated. The electromagnetic loss behavior of multilayer magnetic films with semiconducting properties on the microstrip line in quasi-microwave frequency band was analyzed numerically using a commercial finite-element based electromagnetic solver. The large increase in the absorption performance and broadband characteristics of the semiconducting/insulating layer magnetic films examined in this study were attributed to an increase in the loss factor of resistive loss. The electromagnetic reflection increased significantly with increasing conductivity, and the loss power deteriorated significantly. The numerical results of the magnetic field distribution showed that a strong radiated signal on the microstrip line was emitted with increasing conductivity and decreasing film thickness due to re-reflection of the radiated wave from the surface of the magnetic film, even though the emitted levels varied with film thickness.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.5
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• pp.351-358
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• 2008

Extinction characteristics of hydrogen-air diffusion flames at various pressures are investigated numerically by adopting counterflow flame configuration as a model flamelet. Especially, effect of radiative heat loss on flame extinction is emphasized. Only gas-phase radiation is considered here and it is assumed that $H_2O$ is the only radiating species. Radiation term depends on flame thickness, temperature, $H_2O$ concentration, and pressure. From the calculated flame structures at various pressures, flame thickness decreases with pressure, but its gradient decreases at high pressure. Flame temperature and mole fraction of $H_2O$ increase slightly with pressure. Accordingly, as pressure increases, radiative heat loss becomes dominant. When radiative heat loss is considered, radiation-induced extinction is observed at low strain rate in addition to transport-induced extinction. As pressure increases, flammable region, where flame is sustained, shifts to the high-temperature region and then, shrunk to the point on the coordinate plane of flame temperature and strain rate. The present numerical results show that radiative heat loss can reduce the operating range of a combustor significantly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.241-246
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• 2001

This study considered the transmission loss and frequency characteristecs of window, and examined the transmission loss for each type of windows to design an optimized window for blocking external noise. Moreover this has detect the transmission loss which depending on the thickness and the types(single and fair glass) of window as several major factors of transmission loss design. With this result, this study suggests a window design guide for much silent condition which is below the level of noise standard recommended.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.2
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• pp.171-177
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• 2013

The aim of the present study was to determine the evidence of post-parturient disorders and backfat loss during lactation in sows raised in tropical areas in relation to their backfat thickness before farrowing and postpartum intravenous supportive treatment. Backfat thickness was measured using A-mode ultrasonography at farrowing and weaning ($25.5{\pm}1.4$ d) in 70 sows. The sows were divided into three groups according to backfat thickness before farrowing, i.e., 15.0 to 20.0 mm (n = 21), 20.5 to 25.0 mm (n = 35), >25.0 mm (n = 14) and were categorized into two groups according to the postpartum supportive treatment, i.e., control (n = 31) and treatment (n = 39). After farrowing, the sows in treatment group received the same medications as in control sows. Furthermore an intravenous supportive treatment with amino acids and vitamins was administered in treatment groups. Rectal temperature and clinical signs of the sows including vaginal discharge, udder problems and appetite were determined at d 0, 1, 2 and 3 of parturition. It was found that, on average, the backfat thickness was $22.4{\pm}3.9$ mm at farrowing and $19.9{\pm}2.9$ mm at weaning. The backfat loss and the relative backfat loss during the lactation period were 2.6 mm and 10.6%, respectively. The sows with a backfat of 15.0 to 20.0 mm before farrowing lost less backfat than those with a backfat of 20.5 to 25.0 mm and >25.0 mm (p<0.05). Sows with a backfat of 15.0 to 20.0 mm had a better appetite on d 1 postpartum than sows with a backfat of 20.5 to 25.0 mm (p = 0.020). The percentage of sows losing backfat >10% during lactation were higher in sows with a backfat of >25.0 mm before farrowing (85.7%) than sows with a backfat of 15.0 to 20.0 mm before farrowing (35.0%) (p = 0.008). The percentage of sows with a reduced appetite on d 1 (90.3% vs 71.8%, p = 0.018) and d 2 (61.3% versus 33.3%, p = 0.005) postpartum in the treatment group was lower than the control group. In conclusion, the backfat thickness of sows at farrowing influenced backfat loss during lactation under hot and humid climates. The intravenous supportive treatment of sows with amino acid and vitamins significantly improved the appetite of postpartum sows.

• Journal of the Korean Wood Science and Technology
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• v.37 no.4
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• pp.293-299
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• 2009

In manufacturing the crack-free carbonized boards using fiberboards, shrinking ratio, weight loss and density variation of carbonized boards at each carbonization temperature were investigated. Fiberboards with thickness of 3, 4.5, 6, and 18 mm were carbonized while pressed with pressure plates at different temperature from $400^{\circ}C$ to $1,000^{\circ}C$ using a ordinary laboratory furnace. Either of crack or twist was not observed in fiberboards by adapting the pressing carbonization method. The ratios of shrinkage of length, width, and thickness were 10~25%, 12~25%, and 28~48%, respectively, and shrinkage ratio of thickness was higher than those of length and width with increasing the carbonization temperature. Weight loss tended to increase with increasing the carbonization temperature, but low correlation between weight loss in thickness of fiberboards and carbonization temperature was observed. Density of 3 mm carbonized hardboard had the highest value and it tended to increase with increasing the carbonization temperature.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.7 s.112
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• pp.690-696
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• 2006

Thickness of damping layer in sandwich plate needs to be optimized in order to make modal loss factor of the sandwich plate maximum. Since previous studies were interested in noise reductions over high frequency range, the modal properties were derived based on simply supported boundaries. This conventional formula is approximately applicable to other boundary conditions over high frequency range only. The purpose of this study is to propose a method to determine optimum damping layer thickness of sandwich plate for maximum modal damping in low frequency range when the boundary condition is not a simple support. The conventional RKU equation based on simply supported boundary is modified to reflect other boundary conditions and the modified RKU equation is subsequently applied to determine the optimum damping layer thickness for arbitrary conditions. In order to reflect frequency-dependent characteristics of elastic modulus of the damping layer, an iteration method is proposed in determining the modal properties. Test results on sandwich plates for optimum damping layer thickness are compared with predictions by the proposed method and conventional method.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.2
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• pp.273-276
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• 2001

The storage time of citrus fruit at two different storage temperatures was predicted by quality changes such as weight loss, %Brix and skin thickness. The less weight loss of citrus fruits during storage at $3^{\circ}C$ was observed, compared to those stored at $25^{\circ}C$, whereas %Brix of citrus fruits increased slightly without any difference between storage temperatures. Skin thickness of fruit, represented by pixel, also changed more rapidly at the higher storage temperature. Above parameters with a storage time followed the 0 order reaction pattern. The relationship of skin thickness and storage time of the citrus fruit were resolved to a simple linear equation, and storage time could be predicted using this equation.

• Journal of electromagnetic engineering and science
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• v.16 no.3
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• pp.150-158
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• 2016

This paper reports on a study of LiNiZn-ferrite composite as a radiation absorbent material (RAM). The electromagnetic (EM) wave absorbers are composed of an EM wave absorbing material and a polymeric binder. The surface morphology, chemical composition, weight percent of the ferrite composite of the toroid sample, magnetic properties, and return loss are investigated using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and network analyzer. For preparing the absorbing sheet, chlorinated polyethylene (CPE) is used as a polymeric binder. The EM wave absorption properties of the prepared samples were studied at 4 - 8 GHz. We can confirm the effects of the thickness of the samples for absorption properties. An absorption bandwidth of more than a 10-dB return loss shifts toward a lower frequency range along with an increase in the thickness of the absorber.