Study on correlation between cavitation and pressure fluctuation signal using high-speed camera system

This paper is presenting the correlation between the cavitation and the pressure fluctuation of a propeller. Cavitation images and pressure fluctuation signals were simultaneously acquired by a high-speed camera system connected to pressure sensors for the correlation analysis. The analysis is focusing on the growing and collapsing process of the cavitation and its corresponding patterns of pressure signals. Especially, the relationship between the shape variations of the pressure fluctuation signal and the variations of pressure amplitudes for both the first and second blade frequency components is also studied. From the analysis on the correlation between cavitation behaviors and pressure fluctuation signals, comprehensive explanations on the fundamental mechanisms of the pressure signal generation and on the moment of the peak creation in the pressure signals are found. The shape of overall pressure fluctuation signal on hull surface is affected by not only the effect of cavitation from a single blade but also the superposition of the pressure signals from two adjacent blades when the collapsing of the foregoing blade's cavity and the growing of the following blade's cavity are happening at the same time. In this manner, the overlapping phenomena cause the changes of combination of amplitude levels of each blade frequency.http://deepblue.lib.umich.edu/bitstream/2027.42/84231/1/CAV2009-final27.pd

The impact of IT vendor to firm’s IT outsourcing

This study seeks to better understand the impact of IT vendor to firm’s IT outsourcing in Korea. Using the event study methodology, we empirically analyze the impact of IT vendor in Korea. IT vendors’ characteristics (such as services with asset specificity, size, and nationality) that may affect the success of IT outsourcing are considered. We find that IT outsourcing announcements significantly increase firms’ market value in Korea. In terms of IT vendors’ characteristics, our study find that IT outsourcing announcements with large vendors are statistically significant while with small vendors are not. We also find that the market response to Korean IT vendor is significantly greater than to foreign vendor. However, unlike the US, the difference between IT outsourcing for high asset-specific service and for low asset-specific service is not found

FOOT ARCH STRAIN OF EXCESSIVE PRONATORS DURING TWO-LEGS AND ONELEG STANDING AND WALKING

INTRODUCTION: The movement of plantar fascia under the foot has been characterized by foot arch strain in vitro (Kogler, Solomonidis, & Paul, 1995). The characteristics of the foot arch strain under the static and dynamic conditions in excessive pronators are not well known. Therefore, the purpose of this study is to investigate the foot arch strain during two legs, one-leg standing and walking in excessive pronation

Analysis of Building Energy Savings Potential for Metal Panel Curtain Wall Building by Reducing Thermal Bridges at Joints Between Panels

AbstractTo achieve national greenhouse gas reduction in the building sector, heating and cooling energy in buildings should be reduced. The government has strengthened regulations on insulation performance for building energy savings. However, the building envelope has various thermal bridges. In particular, a metal panel curtain wall comprises a number of thermal bridges at joints between the panels and the fixing units, thus degrading the overall thermal performance. To reduce building energy, it is necessary to reduce thermal bridges in building envelopes. This study aims to analyze the energy saving potential achieved by reducing thermal bridges. For this, the insulation performance and building energy needs of the existing and alternative metal panel curtain wall were evaluated. The alternative metal panel curtain wall that uses plastic molds at joints between panels and the thermally-broken brackets was suggested to reduce heat loss through thermal bridges. As results, the effective U-value of the alternative metal panel curtain wall was reduced by 72% compared with the existing metal panel curtain wall. In addition, annual heating energy needs of the alternative metal panel curtain wall building was reduced by 26%, and annual total energy needs was reduced by 6% because annual cooling energy needs of it slightly increased compared with the existing metal panel curtain wall. In conclusion, the alternative metal panel curtain wall considerably influenced the savings in building energy needs by reducing thermal bridges