• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.141-145
• /
• 2003

The rotary compressor is widely used for the air conditioner because it is efficient and compact. In recent, the need for silent compressors is much stronger than the past. The new type muffler was invented to reduce noise level and to improve sound quality. The new type muffler that has two side discharge holes represents much lower overall noise level, especially noise levels around 1KHz than the old type one that has one center discharge hole in acoustic spectra and dynamic pressure spectra. The noise reduction effects of the new type muffler were verified by noise tests for rotary compressors and air conditioners.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2014.10a
• /
• pp.753-759
• /
• 2014

In this paper, it is investigated that noise generation mechanism of a rotary compressor using experimental method. The measurement was carried out for primary parameters which influence noise characteristics. By using STFT(short time fourier transform), noise sources of a rotary compressor were identified and vibrating modes that increase the noise are verified. Also, it was studied that the correlation between operating speed and noise. Main factors that affect the variation of noise level were considered by the comparison of the experimental results. In addition, a dynamic characteristic of crank shaft was studied and the critical speed was analyzed.

• 유체기계공업학회:학술대회논문집
• /
• 2004.12a
• /
• pp.533-539
• /
• 2004

The rotary compressor is widely used for the air conditioner because it is efficient and compact. In recent, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce noise level and to improve efficiency. The new type muffler that has two side discharge holes and dome shape represents much lower overall noise level, especially noise levels around 1kHz than the old type one that has one center discharge hole In acoustic spectra. Also it has higher air conditioner efficiency by lower oil discharging amount of a compressor than old type one that has rectangular shape and two side discharge holes. The noise reduction and efficiency improvement effects of the new type muffler were verified by tests for rotary compressors and air conditioners.

• Korean Journal of Computational Design and Engineering
• /
• v.8 no.3
• /
• pp.175-183
• /
• 2003

This paper introduces a Web-based vibration analysis system for rotary-type refrigerator compressors. Concern for vibration reduction in compressors has been growing for many years. What is important in vibration reduction is to easily predict the vibration without using a physical compressor. The dynamic model of the compressor is represented as a multi-body dynamic system. Solving the dynamic model is run on a high-performance server. The interfaces of the system are accessible via Web browsers, such as Netscape or Explorer. Anyone who wants to analyze the vibration of the rotary compressor or share the results data can access the system over the Internet regardless of their OS, platform, or location.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.12
• /
• pp.1197-1203
• /
• 2004

This study investigates the air leakage and heat transfer characteristics of a rotary-type air-to-air heat exchanger with a fiber polyester matrix. The leakage airflow rate is measured using a tracer gas method for various ventilation rates and rotational speeds of the matrix wheel. A correlation equation for air leakage is obtained by combining the pressure leakage and the carryover leakage. The pressure leakage is observed to be a function of ventilation airflow rate only, and the carryover leakage is found to be a linear function of rotational speed. The real efficiency of the heat exchanger can be obtained from its apparent efficiencies by taking into account the air leakage ratio. As the ventilation rate increases, the heat recovery efficiency decreases. As the rotational speed of the matrix increases, the efficiency increases initially but reaches a constant value for the rotational speeds over 10 rpm.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.05a
• /
• pp.1129-1130
• /
• 2010

• Proceedings of the SAREK Conference
• /
• 2003.07a
• /
• pp.38-38
• /
• 2003

• Journal of Dental Rehabilitation and Applied Science
• /
• v.27 no.1
• /
• pp.99-107
• /
• 2011

The main objective of nonsurgical retreatment is to disinfect the root canal space for periradicular healing. Thus, efficient removal of the filling material from the root canal system is essential to ensure a favorable outcome. Traditionally, the removal of root canal filling material was performed by stainless steel hand instrument and this procedure is time and effort-consuming. Recently, rotary NiTi retreatment instruments are developed to effective removal of root canal filling material. The aim of this study was to evaluate the effectiveness of stainless-steel hand instrument and rotary NiTi retreatment instrument when removing gutta-percha in curved root canals. For the remaining materials, there were no significant differences between groups. But the rotary NiTi system proved to be faster than hand instruments in removing root filling materials.

• Journal of Aquaculture
• /
• v.19 no.4
• /
• pp.242-246
• /
• 2006

Comparisons of growth and survival rate in different culture systems for juvenile abalone were determined in the West Coast of South Korea from June, 2000 to April, 2001. Daily growth rate reached at the maximum by $148.6{\pm}48.96\;{\mu}m/day$ with a stagnant system and at the minimum by $95.3{\pm}21.45\;{\mu}m/day$ with a sprinkler culture system. Survival rate of the juvenile abalone was significantly higher than that in sprinkler culture with a rotary culture (P<0.05). The highest survival rate was 50.0% in the rotary culture and 38.3% was observed in the stagnant culture system. The results from this study indicate that effective survival and growth rate could be predicted in the rotary culture system.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.27 no.1
• /
• pp.1-8
• /
• 2015

Recently, constructions of coastal structure including wind turbine structure have increased at southwest shore of Korea. There is a big difference of tide which rage from 3.0 m to 8.0 m at south and wet shore of Korea, respectively. In such ocean circumstance, large scour may occur due to multi-directional tidal current and transverse stress of the wind. therefore scour surrounding wind turbine structure can make system unsafe due to unexpected system vibration. In this study, hydraulic resistance capacity, i.e., critical velocity and critical shear stress, was evaluated by RCT. Uni-directional and bi-directional hydraulic resistance capacities of the samples which were consolidated by different preconsolidation pressures were correlated with soil resistivities of same samples. According to the correlation, it is possible to estimate hydraulic resistance capacity from electrical resistivity of soil. Through the updating the correlation for various soil types, it is expected that the hydraulic resistance capacity of whole construction site will be simply determined from the electrical resistivity.