• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.662-665
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• 2005

In this study acoustical characteristics of system air conditioner in different ceiling systems was investigated in anechoic and real conditions. Same Types of air conditioners were installed in two different rooms. The results showed that motor's tonal component was emphasized at near fart of air blast blower in the exposed type while fan's harmonic component is emphasized rather in the enclosed type. This confirms tile result of acoustical intensity mapping which showed that Intensity level of 125Hz octave band increased in the exposed type while there was no noticeable difference at the frequency band in the enclosed type.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.345-346
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• 2010

The HVAC(Heating Ventilation and Air Conditioning) system is only controlled by turn on/turn off operations against to AC 380V input. Therefore, the efficiency of the system is reduced and noise occurs. Also, the blower is shut down at the AC power failure. In this paper, the inverter system with UPS function for the A/C(Air Conditioning) blower is proposed. Proposed inverter system which is powered from the AC and DC voltage can control speed, operation mode, and soft-start time using CAN communication. In case of the CAN communication failure, RS-232 communication could be used to control the hardware directly by the engineer that can solve existing problems. To verify the validity of proposed inverter system, simulations and experiments are carried out.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.293-294
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• 2008

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.7
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• pp.460-467
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• 2010

In housing units constructed recently in Korea, the length of ondol coil is different in each room, so the flow rate of hot water is adjusted by setting valve opening. If the flow rate is not appropriate for heating load, the room temperature seriously deviates from the set temperature range for comfort. In particular, too small valve opening can induce a noise by cavitation. In order to adjust the valve opening, two methods by zone area and a new method by return temperature rise were modelled and simulated using TRNSYS and EES. As a result, heating energy consumption during one week was the same on three methods, but the room temperature of the new method minimally deviated from the range of set temperature with a low possibility of noise.

• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.116-116
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• 2004

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.376-380
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• 2009

The transmission noise characteristics through the ventilating duct was conducted numerically using SYSNOISE. A ventilating system is usually composed of mufflers for preventing noise transmission from the ventilator into indoors through the ducts and distributors for transferring air to or from each room. The transmitted noise characteristics of distributors which have different branch angles and of mufflers having different shapes were analyzed numerically. New duct element combining a muffler and a T-shaped distributor was developed for better noise reduction in this paper. New element's performance was shown numerically.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.148-154
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• 1994

The dynamic analysis of S/N ratio in this study to improve EER has proven to be very effective. The optimized condition can improve EER during the developing process without increasing noise and any other investment. If this method is used widely to design valve systems of compressor for refrigeration and air-conditioning, output capacity will be greatly increased for industry.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.5
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• pp.206-211
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• 2014

The objective of the present study was to identify ventilation problems, and also to suggest new axial fan systems for the improvement of IAQ in the underground parking lots. Numerical results for air mean-velocity, local mean age, and sound power level are presented along with some of fan angles. The results showed the influence of airflow patterns on the fan performances installed in the underground parking lots. Discharge air volume is increased with the angle of the blade. And also, the main factors affecting the noise of the ventilation fan was found to be a rotational speed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.2
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• pp.87-93
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• 2009

Slim telecommunication cabinet cooler, equipped with parallel flow heat exchangers and operating with R-22, is developed. The performance is compared with imported one, equipped with fin-tube heat exchangers and operating with R-134a. Test results show that the newly-developed cooler increases the cooling capacity by 6% and EER by 33%. The refrigerant charge for the developed cooler is 500g compared with 1250g for the imported one. The adoption of parallel flow heat exchanger appears to have reduced the refrigerant charge. In addition, it is shown that the reduced air flow rates through parallel heat exchangers as compared with those through fin-tube heat exchangers are beneficial to the reduction of the equipment noise.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1895-1898
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• 2017

This paper discusses methods for the torque ripple and noise reduction of DC motors for automotive air-conditioning based on electromagnetic field analysis. The target of the motor is a blower motor, and to reduce cogging torque and the torque ripple, the optimum model was selected by deforming the brush or commutator shape. In addition, to reduce the cogging torque, the model design was carried out by applying the skew method and the magnetization method of a magnet to the rotor. For optimization, the shape, material, and drive system of the motor were selected using an electromagnetic field as the analysis tool, and the method of reducing the cogging torque was applied to 4-pole, 12- and 13-slot motors considering the mechanical part. Lastly, this paper confirmed thatthemethod, which proposed how much noise, cogging torque, and vibration are reduced, improves through practical analysis.