• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.416-422
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• 2007

The application analysis of bubble pump on the domestic solar water heater system is presented. The system investigated in this study is a passive device, self pumping and self regulating. It was test to use the bubble pump on solar water heater system. The test experiment has been taken on the existed vacuum tube about the efficiency, working fluid temperature and pressure and circulated power. In order to check the working temperature and working pressure effectively, the bubble pump was test separated from the solar water heater. The equipment consists of the bubble pump, heater and heat exchanger. The main structure of bubble pump was design depend on the character of two phase flow. The complete system was instrumented to measure pressures, temperatures and their relationship with the solar radiation intensity. The theory analysis of design bubble pump has been given and the experiment result analysis has been included in the paper.

• 한국음향학회지
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• 제41권3호
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• pp.255-267
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• 2022

본 논문에서는 오리피스형 공기분사기에서 생성된 기포소음 특성을 고찰하였다. 전반적인 기포소음 특성을 파악하기 위해 Strasberg와 Blake가 각각 제안한 기포소음 스펙트럼을 살펴보았고, 기포소음 계측을 위해 선박해양플랜트연구소의 대형캐비테이션터널에서 공기분사 실험을 수행하였다. 본 실험은 5종의 공기분사기를 이용하여 정지 유체 조건과 유동 조건에서 수행되었다. 계측결과로부터 실험 조건에 따른 기포소음 스펙트럼 특성을 관찰하였고, 회귀분석을 통해 기포소음에 대한 인자별 영향을 분석하였다. 끝으로 회귀분석 결과를 기반으로 기포소음 추정식을 제안하였고 제안된 추정식은 계측결과와 잘 일치함을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2309-2314
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• 2007

The application analysis of bubble pump on the domestic solar water heater system is presented. The system investigated in this study is a passive device, self pumping and self regulating. It was test to use the bubble pump on solar water heater system. The test experiment has been taken on the existed vacuum tube about the efficiency, working fluid temperature and pressure and circulated power. In order to check the working temperature and working pressure effectively, the bubble pump was test separated from the solar water heater. The equipment consists of the bubble pump, heater and heat exchanger. The main structure of bubble pump was design depend on the character of two phase flow. The complete system was instrumented to measure pressures, temperatures and flow-rates at various locations. The theory analysis of design bubble pump has been given and the experiment design has been included in the paper.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.220-223
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• 2002

본 연구에서는 자체 제작한 2L 규모의 bubble-column photobioreactor에서 H. pluvialis의 배양을 시도하였고 astaxanthin의 축적량 증가를 유도하기 위하여 배양시작 20일 후에 light stress를 주었다. 이 방법을 통하여 대조구에 비하여 68%의 건조균체중량 증가와 215%의 astaxanthin 축적량 증가를 유도할 수가 있었고, bubble-column photobioreactor를 이용한 유도배양이 H. pluvialis의 배양에 적합함을 알 수가 있었다.

• 한국멀티미디어학회논문지
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• 제21권3호
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• pp.369-381
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• 2018

Nowadays a personalization algorithm is gaining huge attention. It gives users selective information which is helpful and interesting in a deluge of information based on their past behavior on the internet. However there is also a fatal side effect that the user can only get restricted information on restricted topics selected by the algorithm. Basically, the personalization algorithm makes users have a narrower perspective and even stronger bias because users have less chances to get views of opponent. Eli Pariser called this problem the 'filter bubble' in his book. It is important to understand exactly what a filter bubble is to solve the problem. Therefore, this paper shows how much Google's personalized search algorithm influences search result through an experiment with deep neural networks acting like users. At the beginning of the experiment, two Google accounts are newly created, not to be influenced by the Google's personalized search algorithm. Then the two pure accounts get politically biased by two methods. We periodically calculate the numerical score depending on the character of links and it shows how biased the account is. In conclusion, this paper shows the formation process of filter bubble by a personalization algorithm through the experiment.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.353-356
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• 2006

A set of solutions of the Navier-Stokes equation for the gas inside a spherical bubble with heat transfer through the bubble wall permits to predict correctly behavior of an ultrasonically driven bubble in aqueous solutions of sulfuric acid. Calculation results of the minimum velocity of bubble wall and the peak temperature and pressure are in excellent agreement with the observed ones. Further the calculated bubble radius-time curve displays alternating pattern of bubble motion as observed in experiment.

• Journal of Advanced Marine Engineering and Technology
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• 제12권4호
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• pp.46-52
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• 1988

The cavitation inception in oil hydraulic pipeline was investigated experimentally and numerically. In the experiment, negative pressures below-1 MPa(absolute pressure) were measured, associated with the transient flows in oil hydraulic pipeline. These experimental results show that the common hydraulic oil in the experimental pipeline withstands large tensions. In order to interpret the experimental results on cavitation inception, the growth of a spherical bubble in viscous compressible fluid due to a stepwise pressure drop was investigated by numerical analysis, and the critical bubble radius was obtained. The calculated value of the critical bubble radius corresponding to the negative pressure measured in the experiment is so small that the premised conditions about the bubble shape in the analysis is unsatisfactory. The physical significance of this calculated result implies the fact that there hardly exist free bubbles which can act as cavitation nuclei in the experimental pipeline.

• 수산해양기술연구
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• 제23권3호
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• pp.127-130
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• 1987

유압관로에서의 캐비테이션 발생 기구를 조사할 목적으로, 과도흐름에 수반하여 발생하는 캐비테이션 초생에 관한 실험 및 압력이 급강하 할 때의 기포 성장에 대한 계산을 행하였다. 실험에서 얻은 결과를 기초로 한 계산에서, 작동유가 절대압 영이하의 부압에 노출되어도 캐비테이션이 발생하지 않을 정도의 장력을 갖기 위해서는 소위 말하는 기포(기포 주위의 액체가 연속체로 간주될 수 있을 정도의 크기를 갖는 기포)가 유중에 존재할 가능성은 거의 없음이 입증되었다.

• 지구물리와물리탐사
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• 제26권1호
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• pp.8-17
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• 2023

해양 환경에서의 기포는 바람, 파도, 선박 및 해저 가스 누출을 포함한 여러 요인에 의해 생성된다. 수중에서의 기포는 강력한 산란 신호를 생성하여 음향 신호를 측정하는데 영향을 미친다. 이러한 기포의 특성은 음파 신호의 세기를 감쇠시켜 소음 차단 목적으로 주로 이용되고 있으며, 최근에는 해저에서 대규모로 누출되는 메탄가스 탐지를 위한 연구가 진행되고 있다. 이러한 가스 누출은 기포플룸의 형태를 취하며, 기포의 물리적 특성과 분포 구조를 이해하는 것은 누출된 가스를 기후 변화와 연관성을 파악하는데 중요한 요소 중 하나이다. 본 연구에서는 탄성파 영상화 기법을 이용하여 기포플룸의 분포를 추정하고자 수조환경에서 실험을 수행하였으며, 별도로 제작된 인공기포 발생기, 자료 취득 시스템을 이용하여 기포에 의한 음향 신호를 취득하였다. 기포플룸을 영상화하기 위해 지진파 영상기법 중 역시간 구조보정을 이용하였으며, 획득한 음향 신호의 포락선 신호를 이용하여 기포 분포 패턴을 효과적으로 추정하였다. 영상화 결과의 검증을 위해 추정된 기포플룸의 분포와 광학카메라 영상을 비교하였다. 실험결과 탄성파 영상화 기법 통해 인공 기포플룸의 산란신호를 이용한 영상화가 가능함을 확인하였다.

• 한국연소학회지
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• 제7권1호
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• pp.52-57
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• 2002

A numerical investigation using a commercial CFD program of the Inter-Phase Slip Algorithm has been carried out for detail characteristics of particle motions and bubble behaviors in a two dimensional fluidized bed. The bed simulated has been operated with three different distributor geometries, such as bubble cap, nozzle, and perforated plate types. Experiments using a slit-type two-dimensional fluidized bed and a cylinder-type fluidized bed have been performed in order to confirm the simulation model. In addition, the numerical results are compared with the wellknown correlation of bubble sizes and bubble rising velocities by Mori and Wen [1]. The simulation model that we applied is shown to be useful to understand the relation between bubble behaviors and distributor geometries.