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기포 측정을 위한 단일 층으로 구성되는 망구조 센서 최적화
심재민(Jaemin Sim),박형민(Hyungmin Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Recently, it is highly required to develop the sensor to accurately measure the flow rate or velocity and size of bubbles in two-phase flow. The wire-mesh sensor (WMS) that measures the electrical conductivity of the medium and converts it into the void fraction makes it possible to measure the size and speed of the bubble passing through the sensor without visualization. In our previous work, we reported that the single-layer WMS has enough accuracy in measuring even sub-millimeter scale bubbles. In order to improve the sensor, this study analyzes electrical signal of the single-layer WMS. We apply not only positive-ground pulse voltage but also positive-negative pulse voltage to the transmitter. In addition, based on the electrochemical properties, we suggest the optimal pulse voltage condition for transmitter. Compared to the positive-ground pulse voltage case, more data is expected to be acquired while using positive-negative pulse voltage.
기포 측정을 위한 단일 층으로 구성되는 망구조 센서 최적화
심재민(Jaemin Sim),박형민(Hyungmin Park) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
Recently, it is highly required to develop the sensor to accurately measure the flow rate or velocity and size of bubbles in two-phase flow. The wire-mesh sensor (WMS) that measures the electrical conductivity of the medium and converts it into the void fraction makes it possible to measure the size and speed of the bubble passing through the sensor without visualization. In our previous work, we reported that the single-layer WMS has enough accuracy in measuring even sub-millimeter scale bubbles. In order to improve the sensor, this study analyzes electrical signal of the single-layer WMS. We apply not only positive-ground pulse voltage but also positive-negative pulse voltage to the transmitter. In addition, based on the electrochemical properties, we suggest the optimal pulse voltage condition for transmitter. Compared to the positive-ground pulse voltage case, more data is expected to be acquired while using positive-negative pulse voltage.
3D 프린터를 이용한 상자기성 양친매성 입자 생성기 제작
신성훈(Seonghun Shin),심재민(Jaemin Sim),송륜근(Ryunguen Song),이진기(Jinkee Lee) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12
The amphiphilic particle having multi surface properties is one of the materials that are possibly used to separate the oil/water. By forming a stable paramagnetic Janus emulsion and polymerizing it, the functional particle can be fabricated. This particle absorbs oil from water and its motion is controllable by electromagnetic force. Even though a large advantage of these particles, the production of uniform Janus emulsion and continuous polymerization has been limited. To resolve this problem, we built a 3D printed microfluidic platform for monodispersed Janus emulsion mass production. The fabricated particle had an amphiphilic characteristic with bowl-like shape. We analyzed the relationship between capillary number and the particle diameter and observed the change of interfacial tension and morphology as the surfactant concentration changes. And we confirmed that the particles we fabricated adsorb the oil and are attracted to the permanent magnet. It is expected that mass-production of these Janus particles would be effective on enhance the efficiency of oil separation.
조성수(Seongsu Cho),신성훈(Seonghun Shin),심재민(Jaemin Sim),이진기(Jinkee Lee) 한국가시화정보학회 2021 한국가시화정보학회지 Vol.19 No.2
River and stream are the important water supply source in our lives. Eutrophication causes excessive green algae growth including microcystis, which makes harmful to ecosystem and human health. Therefore, the water purification process to remove green algae is essential. In Korea, green algae alarm system exists depending on the concentration of green algae cells in river or stream. To maintain the growth amount under control, green algae monitoring system is being used. However, the unmanned, small and automatic monitoring system would be preferable. In this study, we developed the 3D printed device to measure the concentration of green algae cell using microfluidic droplet generator and deep learning. Deep learning network was trained by using transfer learning through pre-trained deep learning network. This newly developed microfluidic cell counter has sufficient accuracy to be possibly applicable to green algae alarm system.
조성수(Seongsu Cho),신성훈(Seonghun Shin),심재민(Jaemin Sim),이진기(Jinkee Lee) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
River is the major water source for city. When eutrophication is occurred, green algae in water is increased abnormally, and it is harmful to ecosystem in river, and human health. To resolve this problem, additional purification procedure is needed. So, monitoring the green algae in river is important to manage the quality of water supply in city. Korean government manage the green algae alarm system based on the concentration of green algae cell in river. To maintain this system well, effective green algae concentration measurement device is needed. In this study, we developed the microfluidic device to measure the concentration of green algae cells in sample based on droplet generation and deep learning. We compared the result with the result measured by haematocytometry and confirmed that it had enough accuracy to apply on green algae alarm system.