• Journal of the Korean earth science society
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• v.37 no.7
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• pp.408-419
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• 2016

To investigate the in-situ sound velocity of sediment in the southwestern part of the East Sea, the laboratory sound velocity was measured using the pulse transmission technique. The sediment sound velocity measured in laboratory was corrected to in-situ sound velocity based on the seafloor temperature, seawater sound velocity, Kim et al. (2004) model, and Hamilton (1980) model. The distribution of the corrected in-situ sound velocity applying Kim et al. (2004) and Hamilton (1980) models reflects the characteristics of sediments of the study area and shows a similar distribution pattern. The correction for in-situ sound velocity was mostly influenced by seafloor temperature. Then, correction of sound velocity using seafloor sediment temperature data should be accomplished for conversion of laboratory data to in-situ sound velocity.

• Journal of the KSME
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• v.50 no.8
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• pp.41-45
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• 2010

동맥에서의 맥파전달 속도는 동맥 혈류와 혈관벽의 상호작용에서 유발되며, 동맥경화, 당뇨합병증 등의 진단 등에 널리 사용되고 있다. 증가된 맥파전달속도는 혈관 노화 및 여러 병리학적 상황과 연관된 것으로 보고되고 있다. 따라서 이 글에서는 이러한 동맥 맥파전달속도의 생체유체역학적 발생 기전 및 의학적 중요성에 대하여 논의하며, PWV진단의 문제점 및 향후 발전방향에 대해서도 기술한다.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.67.2-67.2
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• 2010

구형 분자운에서의 복사전달문제를 탈출확률방법에 기초하여 non-local method로 풀었다. 매질을 여러 개의 구간으로 나누고 각 구간에서 물리량이 일정하다고 가정하여 복사전달식을 전개하였고 뉴턴방법을 채택하여 수렴속도를 빠르게 하였다. 이번 연구에서는 분자운 내부의 속도구배가 작든 크든 상관없이 복사전달식을 풀 수 있도록 수치코드를 개발하였다. 우리의 계산 결과는 속도구배가 큰 경우에는 LVG방법을 사용한 결과와 일치하고, 분자운이 정적인 경우에도 이전 연구의 결과와 일치한다. 앞으로 이 방법에 line-overlap과 saturation효과를 추가하여 만기형 별에서의 SiO메이저 연구에 활용할 계획이다.

• Journal of the Korean Wood Science and Technology
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• v.28 no.2
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• pp.19-24
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• 2000

Effects of the cross-sectional dimension and moisture profile of wood specimens on the ultrasonic sound velocities of radiata pine heartwood and sapwood. Each moisture profile model specimen was made by composing five wood pieces with various moisture contents. As the cross-sectional dimensions decreased the ultrasonic velocities of both heartwood and sapwood decreased by 4~8%. In the ultrasonic signals transmitted through the specimens low frequency components more dominated than high frequency components as the dimension of cross section increased. The specimens with the same average MCs and different moisture profiles showed different ultrasonic velocities. By plotting the ultrasonic velocities against the average moisture contents of the inner three pieces of the moisture profile model specimens it was revealed that three distinct plot patterns existed.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.320-327
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• 2015

This study implicates a quality evaluation technique for lining concrete using the ultra-sonic technique and proposed a classification for quality evaluation. From the comparison of test results, an improved result comparable to the results by destructive test can be obtained by using averaged transmission velocity of velocities obtained at pure space and central space between two sensors of ultrasonic tester. It is also shown that strength evaluation by ultra-sonic method is not reliable and an evaluation according to the transmission velocities can be improved method for the strength evaluation of concrete.

• Journal of the Korean Magnetics Society
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• v.22 no.4
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• pp.136-141
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• 2012

In the this research, two simultaneous peaks of radial artery pulse wave and ECG pulse wave measured by using clip-type pulsimeter and ECG were investigated in order to analyze pulse wave velocity. The measured value of a pulse wave velocity is about 5~7 m/s, it is proved one new method to measure an exact value of pulse wave velocity more than the typical biomedical signal monitoring system. This result implies that data measured by the oriental medical diagnosis apparatus as pulsimeter is clinically used in future.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.277-282
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• 1989

Xanthan gum is a biopolymer produced by Xanthomonas campestris. In xanthan gum fermentation, the fermentation broth changes to highly viscous non-Newtonian fluid as xanthan gum concentration increases. Maximum xanthan gum concentration is limited by high viscosity of the broth since mass transfers of nutrient and oxygen are inhibited. Int this study the mass transfer effects were investigated in batch and fed-batch fermentations at various agitation speeds and by separate oxygen transfer experiments. Xanthan gum production rate was observed to be largely dependent on oxygen transfer coefficient; while cell growth rate was not affected highly by this factor.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1997.05a
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• pp.83-86
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• 1997

• Microbiology and Biotechnology Letters
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• v.26 no.6
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• pp.529-536
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• 1998

In a 20 L fermentor experiments the level of dissolved oxygen (D.O.) strongly affected growth and PHBV production of Azotobacter vinelandii UWD. A higher D.O. (5%) increased specific cell growth rate two folds but PHBV production was 17 folds higher (62.3 wt%) at a lower D.O.(1%) level. D.O. level was not a good criterion to evaluate the effect of aeration on fermentation characteristics of A. vinelandii UWD. This strain maintained an equal D.O. (5%) by decreasing its oxygen consumption rate when oxygen transfer rate (OTR) was decreased by changing agitation speed at a fixed aeration rate. OTR rather than D.O. was a criterion to explain the effect of aeration on the cell growth and PHBV production. At 5% D.O. with a lower 0TR cell growth rate decreased but PHBV production (57.3 wt%) approached to that (62.3 wt%) of the lower (1%) D.O.

• Journal of Biomedical Engineering Research
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• v.24 no.2
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• pp.121-126
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• 2003

The purpose of this work was to assess and quantify whether the beneficial effects in long-term gas exchange at exciting frequency were obtained at different frequencies as well and then to develop a vibrating intravascular lung assist device(VIVLAD), for Patients suffering from acute respiratory distress syndrome(ARDS) or chronic respiratory problems. We investigate the optimal condition of the frequency band excited with new vibrator at state of limit hemolysis when blood hemolysis came to through a membrane vibration action. The experimental design and procedures were given for a device used to assess the effectiveness of membrane vibrations. Quantitative experimental measurements were performed to evaluate the performance of the device . and to identify membrane vibration dependence on blood hemolysis. We developed an analytical solution for the hydrodynamics of flow through a bundle of sinusoidally vibrated hollow fibers that is used to provide some insight into how wall vibrations might enhance the performance of the VIVLAD. In the result, it was measured that the effect of various excited frequencies in gas transfer rate and hemolysis from the maximum gas transfer rate at no vibration when the maximum gas transfer rates showed at module type 6, module type 6 consisted of 675 hollow fiber membranes The maximum oxygen transfer rate was caused by the occurrence of maximum amplitude and transfer of vibration to hollow fiber membranes when it was excited by the frequency band of 7Hz at each blood flow rate. because this frequency became the End mode resonance frequency of the flexible in blood flow. Also, when module type 6 was excited at an excited frequency of 7Hz. blood hemolysis was low. Therefore, we decided that the limit of hemolysis frequency is 7Hz . because maximum amplitude occurred at this frequency.