• 대한기계학회논문집B
• /
• 제24권10호
• /
• pp.1399-1408
• /
• 2000

A 2-dimensional temperature field measurement technique using PLIF (Planar Laser Induced Fluorescence) was developed and it was applied to an axisymmetric buoyant jet. Rhodamine B was used as a fluorescent dye. Laser light sheet illuminated a two-dimensional cross section of the jet. The intensity variations of LIF signal from Rhodamine B molecules scattered by the laser light were captured with an optical filter and a CCD camera. The spatial variations of temperature field of buoyant jet were derived using the calibration data between the LIF signal and real temperature. The measured results show that the turbulent jet is more efficient in mixing compared to the transition and laminar jet flows. As the initial flow condition varies from laminar to turbulent flow, the entrainment from ambient fluid increases and temperature decay along the jet center axis becomes larger. In addition to the mean temperature field, the spatial distributions of temperature fluctuations were measured by the PLIF technique and the result shows the shear layer development from the jet nozzle exit.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2004년도 추계학술대회 논문집
• /
• pp.86-89
• /
• 2004

One most feasible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been successfully achieved so far due to various limitations in the light illumination and fluorescence signal detection. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having five(5) microns thickness by use of a micro focus laser line generator. The laser sheet beam illuminates an exact plane of concentration measurement field to increase the signal to noise ratio and considerably reduce the depth uncertainty. Nile Blue A was used as fluorescent dye for the present LIF measurement. The enhancement of the fluorescent intensity signals was performed by a solvent mixture of water $(95\%)$ and ethanol (EtOH)/methanol (MeOH) $(5\%)$ mixture. To reduce the rms errors resulted from the CCD electronic noise and other sources, an expansion of grid size was attempted from $1\times1$ to 3(3 or 5(5 pixel data windows and the pertinent signal-to-noise level has been noticeably increased accordingly.

• 대한기계학회논문집B
• /
• 제30권9호
• /
• pp.834-841
• /
• 2006

In the present wort the Laser-induced Fluorescence (LIF) technique and Confocal Laser Scanning Microscopy (CLSM) have been combined to measure the temperature distribution across a micro-scale liquid layer as a direct and non-invasive method. Only the fluorescent light emitted from a very thin volume around a focal plane can be selectively detected, and it enables us to measure the liquid temperatures even at the close vicinity of the walls. As an experimental verification, a test section consists of two flat plates (for heating and cooling, respectively) separated by about 240 microns was made, and the methanol mixed with a temperature-sensitive dye, Rhodamine B, was filled in the gap between them. The measured temperature distribution across the gap showed good linearity, which is a typical characteristic of conduction heat transfer through a thin liquid layer. In result, the CLSM-LIF technique proposed in the present study was found to be a promising method to measure the local temperatures in the liquid flow field in microfluidic devices.

• 전기학회논문지P
• /
• 제57권2호
• /
• pp.79-83
• /
• 2008

In this paper, we introduced a LIF measurement method and summarized the theoretical side. When an altered wavelength of laser and electric power, lamp applied electric power, we measured the relative density of the metastable state in mercury after observing a laser induced fluorescence signal of 404.8nm and 546.2nm, and confirmed the horizontal distribution of plasma density in the discharge lamp. Due to this generation, the extinction of atoms in a metastable state occurred through collision, ionization, and excitation between plasma particles. The density and distribution of the metastable state depended on the energy and density of plasma particles, intensely. This highlights the importance of measuring density distribution in plasma electric discharge mechanism study. The results confirmed the resonance phenomenon regarding the energy level of atoms along a wavelength. change, and also confirmed that the largest fluorescent signal in 436nm, and that the density of atoms in 546.2nm ($6^3S_1{\to}6^3P_2$) were larger than 404.8nm ($6^3S_1{\to}6^3P_2$). According to the increase of lamp applied electric power, plasma density increased, too. When increased with laser electric power, the LIF signal reached a saturation state in more than 2.6mJ. When partial plasma density distribution along a horizontal axis was measured using the laser induced fluorescence method, the density decreased by recombination away from the center.

• 한국자원식물학회지
• /
• 제35권4호
• /
• pp.417-427
• /
• 2022

본 연구에서는 섬괴불나무 열매(LIF), 잎(LIL) 그리고 줄기(LIS) 추출물의 면역증진 활성과 섬괴불나무 열매(LIF) 추출물의 항비만 활성을 평가하였다. 섬괴불나무 열매(LIF), 잎(LIL) 그리고 줄기(LIS) 추출물은 RAW264.7 세포에서 NO, iNOS, COX-2, IL-1𝛽, TNF-𝛼와 같은 면역증진인자의 생성을 증가시켰으며, IL-1𝛽의 발현은 NO생성과 관련된 것으로 보여진다. 면역증진인자은 TLR2/4를 통해 MAPKs중 p38 그리고 JNK를 자극하여 발현이 유도되는 것으로 판단된다. 항비만 실험에서, 섬괴불나무 열매(LIF) 추출물은 AMPK, HSL, ATGL의 발현 증가와 perilipin-1 발현 억제를통해 지질분해를 유도하여 세포 내 지질축적을 억제하는 것으로 나타났으며, 갈색지방세포로의 분화유도와 에너지 대사에 관여하는 인자인 PRDM16, PGC-1𝛼의 발현유도를 통해서도 지질축적을 억제하는 것으로 판단된다. 향후 섬괴불나무 추출물은 건강 보조제 및 기능성 식품으로의 활용이 가능할 것으로 판단되지만, 섬괴물나무 추출물의 어떠한 성분이 면역과 항비만 활성에 영향을 미치는지에 대한 성분분석이 필요하다. 또한, 본 연구는 세포를 이용한 실험으로 정확한 분석을 위해서는 동물모델을 이용한 섬괴불나무 추출물의 면역증진 및 항비만 활성에 관한 추가적인 연구가 진행되어야 할 것이다.

• 한국분무공학회지
• /
• 제7권4호
• /
• pp.42-49
• /
• 2002

In this study, quantitative measurement of nitric oxide concentration distributions were investigated in the laminar CH4/O2/N2 premixed flame by laser-induced fluorescence (LIF). The NO A-X (0,0) vibrational band around 226nm was excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interference from Rayleigh scattering and O2 fluorescence. The measurements were taken in CH4/O2/N2 premixed flame with equivalence ratios varying from $1.0{\sim}1.6$, and a fixed flowrate of 5slpm. NO was found to produce primarily between an inner premixed and an outer nonpremixed flame front, and total NO concentration is raised when equivalence ratios increase. These results suggest that prompt NO is likely to contribute to NO formation in CH4/O2/N2 premixed flame. Furthermore, this trend was well matched with previous works.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집B
• /
• pp.156-161
• /
• 2000

In this study, quantitative nitric oxide concentration distributions are investigated in the post-flame zone of laminar premixed $CH_4/O_2/N_2$, flames by laser-induced fluorescence (LIF). The measurements are taken in flames for different equivalence ratios varying from $0.8{\sim}1.4$, and flow rate is fixed as 5slpm. The NO A-X (0,0) vibrational band around 226 nm is excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interferences from Rayleigh scattering and $O_2$ fluorescence. NO concentration is rised when equivalence ratios increase at different vertical distances form nozzle tip. In any case, the maximum NO concentration reaches the maximum in reaction zone.

• 대한기계학회논문집B
• /
• 제33권5호
• /
• pp.311-317
• /
• 2009

Due to extremely small device size and velocity scale, mixing in microchannel take place very slowly by way of molecular diffusion transport. Mixing enhancement becomes a central issue in microfluidics for biomedical and chemical applications. In this work, The optimization results and validation through experiment and fabrication. In this efficient micromixer design, it is essential to evaluate mixing efficiency with good precision. Mixing efficiency for Y-channel micromixer is measured by fluorescence intensity using LIF(Laser Induced Fluorescence) Confocal Microscope. The Y-channel micromixers are fabricated with polydimethylsiloxane(PDMS). Nile Blue A is injected into the micromixer as a fluorescence dye for measuring of fluorescence intensity by He/Ne laser. Throughout the experiments and computer simulation, accurate mixing efficiency evaluation process for a PDMS Y-channel micromixer is established.

• 기계저널
• /
• 제33권12호
• /
• pp.1031-1042
• /
• 1993

연소현상에 대한 이해를 증가시키기 위하여 화염을 이용한 많은 실험적 연구가 이루어져 왔다. 특히 연소 모델의 개선과 증명을 위하여는 화염에서의 성분 농도 측정이 필수적이며, 최근에 들어 측정 가능해진 래디컬성분의 측정은 연소해석분야에 많은 진전을 가져왔다. OH, H 및 O는 연료의 분해 (decomposition) 및 연소 산화물생성 이외에도 CO와 NO 같은 공해물질의 형성등 연소과정에서 매우 중요한 래디컬들이며, 특히 화염영역에서의 OH의 전파(transport)는 화염의 점화 및 안정성 (stability)에도 큰 영향을 미친다. OH래디컬은 연소과정에서 가장 중요한 성분 중 하나이며, 또한 스펙트럼이 비교적 잘 알려져 있어 레이저 유도 형광의 적용이 용이하므로 화염에서의 OH농도 측정에 LIF(laser induced fluorescence) 또는 PLIF(planar laser induced fluorescence)가 널리 사용되고 있다. 따라서 LIF 및 PLIF의 원리 및 연소분야에서의 응용을 OH농도 측정을 중심으로 소개하고자 한다.

• 한국분무공학회지
• /
• 제20권1호
• /
• pp.1-6
• /
• 2015

Visualization of the mixing pattern in a non-element mixer was carried out using laser induced fluorescence(LIF) to evaluate characteristics of mixer consisting of the main flow pipe and branch flow pipes. The branch flows were injected periodically with the period $T_{in}$ normal to the main flow, and rhodamine B was mixed into the most upstream branch flow to visualize mixing pattern in the main flow pipe by LIF. The length of boundary line L of the LIF image was measured. In this study, a numerical analysis was performed to identify the mixing process of the non-element mixer, and the results were compared with experimental results. Each result was almost the same. When the number of branch flows is increased, the mixing pattern became complicated and was supposed to become chaotic. The length of boundary line L increased exponentially with an increase in the number of branch flows.