• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.196-201
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• 2003

Axial fans are widely used for automotive engine cooling device due to their ability to produce high flow rate to keep engine cool. At the same time, the noise generated by these fans causes one of the most serious problems. Especially, engine cooling fan noise in idle condition of a car is noticeable. Therefore, the high efficient and low-noise fan is seriously needed. When a new fan system is designed, system resistance and non-uniform inflow are the key factors to get the high performance and low noise fan system. In this study, experimental study on the fan and system was carried out and brought a successful result of performance and noise from a designed fan. And through the modification of the fan system, the fan produced more flow rate and became less noisy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.211-212
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• 2009

• Journal of Sasang Constitutional Medicine
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• v.10 no.1
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• pp.143-160
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• 1998

PURPOSE This studied the biomechanical body segment parameters of Korean adults with reference to Sasang Constitutional Medicine(SCM). We anlyzed the characteristics of Sasang constitution through Body Measurement, Immersion Method, and Reaction Board Method. SUBJECT Subjects were 72 persons. There were made 49 and Female 23. Mean age was . And There were Taeumin 30, Soyangin 17, and Soeumin 25. METHOD The items of Body Measurement were 51. Limbs were measured right side. Volume was gained with Immersion Method and Weight was calculated with the density equation for limbs from Drills and Contini. Center of Mass was gained with Reaction Board Method. RESULT 1. In Body Measurement there were the significant differences with each constitution of man's circumference. 2. In Volume there were the significant differences between Taeumin and Soeumin in mand. And the volume rate of head and neck, hand, and foot was the lowest in Taeumin, but the highest in Soeumin. 3. In center of mass Soyangin was higher than others.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.11
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• pp.1107-1114
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• 2004

Axial fans are widely used for automotive engine cooling device due to their ability to produce high flow rate to keep engine cool. At the same time, the noise generated by these fans causes one of the most serious problems. Especially, engine cooling fan noise in idle condition of a car is noticeable. Therefore. the high efficient and low-noise fan is seriously needed. When a new fan system is designed, system resistance and non-uniform inflow are the key factors to get the high performance and low noise fan system. In this study, aerodynamic and acoustic calculations are carried out on the automotive cooling fan and system. Effects of various design parameters are studied through the free wake analysis and experiments. Better performance and noise characteristic are obtained for the new design fan using the methodology. Furthermore through the modification of the fan system geometry parameters, the fan system produce more flow rate and become less noisy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.858-861
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• 2006

In this paper, a study on the noise reduction in a mobile fuel cell system is presented. Among various fuel cell systems around 20W capacities designed for mobile electronic devices, the active direct methanol fuel cell (DMFC) systems have been recently developed. In such systems, the primary noise source is the air pump which provides sufficient air flow ($5{\sim}6$ liter/min) for electrochemical reaction with methanol fuel while the noise contributions from other auxiliary parts are relatively small. Especially, the discrete noise tones generated by the air pump are dominant and those frequency peaks related to the rotor harmonics are needed to be suppressed by a silencer. Therefore. the Herschel/Quinke (HQ) tubes, which use the out-of-phase cancellation of acoustic waves propagating through direct and indirect pathways, are applied to the inlet of the air pump. Performance of noise reduction with HQ silencer is analytically estimated by calculating the transmission. The length and number of thin HQ tubes are optimized to decrease the radiated noise. As a result, the sound pressure level could be successfully reduced by about 10 dB after applying three serially connected HQ tubes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.821-825
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• 2005

Tilt rotor aircraft was developed for satisfying VSTOL (vertical short take off and landing) capability and cruise performance. However the noise generated by tilt rotor system causes one of the most serious problems. In this paper, noise characteristics of tilt rotor system in hovering flight are predicted by using free wake method and Lowson's formula. The flow field of the tilt rotor is simulated by using time marching free wake method, and the free field acoustic pressure is calculated through Lowson's formula. The predicted results are compared with experimental data at various observing positions. In the near field, they show good agreement with experimental data regardless of rotating speed and collective pitch angles of 6, 8 and 10 degree, although there are some discrepancies between prediction and experiment in the far field and at the rotating axis in the near field. It seems that the reason of these discrepancies is difference of unsteady force fluctuation between experiment and calculation.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.305-308
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• 2000

본 논문에서는 한국어에 나타난 외래어 중에서 외국어(영어/독일어)의 $[\int]$음이 어떻게 인식되고 해석되었는지를 살펴보았다. 특히 본 논문에서는 $[\int]$음의 영어와 독일어 발음과 한국어의 대응되는 분절음이 일대일 대응을 이루고 있지 못하다는 것을 보이고 이런 대응관계를 설명하기 위해 어떤 정보가 필요한지에 대해 살펴보았다. 즉, 독일어와 영어에서 음절의 말음으로 쓰인$[\int]$음이 한국어에서는 [쉬/시]로 인식되는데 반해 본토어에서 $[\int]$음이 음절초음의 일부로 사용된 경우에는 한국어의 외래어에서 (슈)로 화자에게 인식되고 또 문자로 표현된다 따라서 본 논문에서는 음절초음의 일부로 나타나는 외국어의 $[\int]$음과 음절말음으로 나타나는 외국어 $[\int]$음의 음성학적 기호를 분석해보고 한국어에서 서로 다른 표면형을 형성하는 이유가 본토어의 (음절 초음/말음이라는) 음운론적 특성에 기인하는 것인지 혹은 현재까지 우리가 알고 있지 못했던 $[\int]$음의 발음 위치에 따른, 즉 동시조음(coarticulation) 현상 때문에 생긴 변이음 때문인지에 대한 규명을 시도하였다. 외국어 화자의 발성실험을 통해, 한국어에서 /쉬/로 인식되는 독일어와 영어의 $/\int/$음은 /슈/로 인식되는 $/\int/$음보다 마찰소음의 peak frequency가 높거나 지속시간이 길게 나타났다 이런 결과를 근거로 영어와 독일어의 $/\int/$ 음이 한국어의 /쉬/음과 /슈/음으로 구분될 때 사용되는 음성자질은 크게 2가지, 즉 마찰소음의 peak frequency와 지속시간이며, 둘 중 한가지만 있어도 구분은 가능하나 이 2가지가 동시에 존재할 때 /쉬/음과 /슈/음의 구분이 현저히 용이해진다는 가설을 세워보았다.