• 한국가시화정보학회지
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• 제4권2호
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• pp.32-36
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• 2006

Recently there are many researches about single flow and two-phase flow phenomena in the mini and microchannel. But from this result the principle in the microchannel was not explained clearly. In this paper two-phase flow pattern was visualized in the micro-multi-branched-channel using a high speed camera. Microchannel was fabricated with PDMS and glass slide. The velocity profile was obtained by a Micro PIV. Then flow boiling at the near inlet area was occurred and vapor was moved in the micro-multi-branched-channel.

• Journal of Mechanical Science and Technology
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• 제20권6호
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• pp.840-848
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• 2006

We carried out numerical studies to investigate the single- and two-phase flow characteristics in the single- and multi-channels. We used the finite volume method to solve the mass and momentum conservation equations. The volume of fluid model is used to predict the two-phase flow in the channel. We obtained the distribution of velocity fields, pressure drop and air volume fraction for different water mass flow rates. We also calculated the distribution of mass flow rates in the multi-channels to understand how the flow is distributed in the channels. The calculated results for the single- and two-phase flow are partly compared with the present experimental data both qualitatively and quantitatively, showing relatively good agreement between them. The numerical scheme used in this study predicts well the characteristics of single-and two-phase flow in a multi-channel.

• 한국군사과학기술학회지
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• 제27권1호
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• pp.43-50
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• 2024

Large planar military antenna boasts a range of electrical components, including TRA(Transmit-Receive Assembly), signal processors, etc. which engage in computations and calculations. These processes generate a significant amount of heat, leading to unforeseen consequences for the equipment. To mitigate these adverse effects, it's imperative to implement a cooling system that can effectively reduce heat-related issues. Given the antenna's intricate nature and the multitude of components it houses, a two-step estimation process is necessary. The first step involves a comprehensive model calculation to determine the total flow characteristics, while the second step entails a thermal analysis of individual TRA set. In this study, we depicted an antenna set using simplified 3D models of its components, considering their material and thermal properties. The sequential analysis process facilitated the calculation of branched flow rates, providing insights into the individual TRA. This approach also allowed us to design a cooling system for the TRA set, assessing its thermal stability in high-temperature environments. To ensure the optimal performance of TRA, breaking down the analysis into stages based on the cooling system's structure can assist operators in predicting numerical results more effectively.

• 한국전자파학회논문지
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• 제23권2호
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• pp.244-250
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• 2012

본 논문에서는 소형화된 대칭형 다이폴 안테나와 이를 이용한 배열 구조를 제안하였다. 제안된 안테나 배열 구조는 표재성 암 치료를 위한 고온 온열 치료의 전자기파 방사체에 사용된다. 소형화된 다이폴 안테나는 가온 균일성 향상을 위하여 양 갈래 다이폴과 정합 구조가 대칭형으로 설계되었고 이를 이용하여 $2{\times}2$ 배열 구조가 제작 및 측정되었다. 제작된 배열 구조는 전자파 흡수율과 생체열 방정식에 의하여 모의 실험되고, 다중 채널 온도계를 사용하여 30분 및 60분 간의 온도 분포가 측정되었다. 그 결과, 다이폴 안테나에 각각 2 W의 전력을 공급하였을 때 2.7도와 3.3도의 온도가 상승하였다. 측정 환경에서의 모의 실험 결과와 측정 결과가 일관성을 보였으며, 실제 치료 환경을 가정한 모의 실험을 통하여 실제 의료 기기 활용에 많은 도움이 될 것으로 기대된다.