• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2004년도 학술발표회
• /
• pp.463-467
• /
• 2004

Rosette-type diffusers with four-ports per riser are constructed in relatively shallow water in Korea. However, the trajectorial bending phenomena due to lower-pressure inside the surrounded buoyant jets on the riser was not considered in most models and was not observed without any experimental results. The buoyant jet behavior affected by the bending effect where there have been growing interests need to be verified experimentally and need to be preceded in the analysis of the characteristics of the buoyant jets oil a riser. The hydraulic model experiments have been carried out to investigate the characteristics of the behavior of horizontal buoyant jets discharged from a Rosette-type riser with four ports as well as single port over a certain range of the experimental conditions including initial momentum and initial buoyancy using LIF (Laser Induced Fluorescence) system to obtain concentration fields. The intensity of the fluorescent light in each pixel on the images obtained from LIF system with the tracer of Rhodamine H was converted to the local dye concentration with a set of calibration procedures to account for the non-uniform distribution of light intensity and the attenuation of light energy by water medium. The experimental results shows that the trajectories from Your ports tend to bend more and more to the inner side with the increase of the densimetric Froude number while the buoyant jet from a single port rises up without any bending phenomena. The previous models, VISJET and Seo et al. (2002), do not simulate the trajectories well except the region before the bending section. This study will focus on the analysis of the behavior of the buoyant jets for mainly a Rosette-type riser by conducting hydraulic model experiments using LIF system.

• Reproductive and Developmental Biology
• /
• 제36권1호
• /
• pp.21-26
• /
• 2012

Suspension culture is a useful tool for culturing embryonic stem (ES) cells in large-scale, but the stability of pluripotency and karyotype has to be maintained $in$ $vitro$ for clinical application. Therefore, we investigated whether the chromosomal abnormality of ES cells was induced in suspension culture or not. The ES cells were cultured in suspension as a form of aggregate with or without mouse embryonic fibroblasts (MEFs), and 0 or 1,000 U/ml leukemia inhibitory factor (LIF) was treated to suspended ES cells. After culturing ES cells in suspension, their karyotype, DNA content, and properties of pluripotency and differentiation were evaluated. As a result, the formation of tetraploid ES cell population was significantly increased in suspension culture in which ES cells were co-cultured with both MEFs and LIF. Tetraploid ES cell population was also generated when ES cells were cultured alone in suspension regardless of the existence of LIF. On the other hand, the formation of tetraploid ES cell population was not detected in LIF-free condition, in which MEFs were included. The origin of tetraploid ES cell population was turned out to be E14 ES cells and not MEFs by microsatellite analysis and the basic properties of them were still maintained despite ploidy-conversion to tetraploidy. Furthermore, we identified the ploidy shift from tetraploidy to near-triploidy as tetraploid ES cells were differentiated spontaneously. From these results, we demonstrated that suspension culture system could induce ploidy-conversion generating tetraploid ES cell population. Moreover, optimization of suspension culture system may make possible mass-production of ES cells.

• 한국응용과학기술학회지
• /
• 제33권1호
• /
• pp.136-142
• /
• 2016

무질서 매질에서 형광, 산란과 응집의 영향은 파장과 산란된 형광세기로 나타내는데, laser induced fluorescence(LIF) 분광학에 의한 분자특성으로 나타난다. 산란매질에서 광학적 효과는 광학적 파라미터들(${\mu}_s$, ${\mu}_a$, ${\mu}_t$)에 의해 표현되고 응집은 고-액상 분리공정과 Photodynamic therapy에서 중요하게 활용되고 있다. 따라서 입자가 서로 접근될 때 콜로이드 입자들의 상호작용을 LIF와 응집효과로 분석하였다. 우리는 레이저 광원에서 검출기까지 거리의 함수에 의해 in vitro 시료의 산란과 형광 스펙트라를 측정하였다. 산란계수 ${\mu}_s$는 산란체의 입자가 증가함에 크게 나타났다. 그리하여 purple membrane vesicle과 ${\beta}$-carotene의 혼합물의 매질에서 광원에서 검출기에 의한 거리에 대한 측정된 값(I, ${\delta}$)이 거리가 가까워짐에 따라 크게 나타났다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회B
• /
• pp.2585-2590
• /
• 2007

In this paper, a technique of simultaneously measuring the velocity and the temperature in micro-scale flow is proposed. This method uses particle tracking velocimetry (PTV) for measuring the velocity and laser induced fluorescence (LIF) for measuring the temperature. To measure the accurate velocity and temperature, images for PTV and for LIF are separated by using two light sources and a shutter which is synchronized with a camera. By using only one camera, measurement system can be simplified and the error from complicate optical system can be minimized. Error analyses regarding the concentrations of fluorescent dye and particle and the light source fluctuation are also conducted. It is found that the error of the temperature and the velocity highly depends on the concentration of fluorescent particles which are used for PTV. This technique is applied to the simultaneous measurement of the velocity and the temperature in the electrokinetic flow. It is found that the velocity and temperature vary with the electric field strength and the concentration of electrolyte.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
• /
• pp.61-68
• /
• 1997

The morphology and size distribution of chromium oxides and the concentration measurement of atomic arsenic have been studied in laminar diffusion flames. Nitrogen was added to vary flame temperatures in hydrogen flames. Ethene flames were used in order to investigate the potential for interaction between the soot aerosol that is formed in these flames and the chromium aerosol. Two sources of chromium compounds were introduced: chromium nitrate and chromium hexacarbonyl. A detailed investigation of the morphology was carried out by scanning electron microscopy (SEM). The amounts of Cr(VI) and total Cr were determined by a spectrophotometric method and by X-ray fluorescence spectrometry, respectively. Also, LIF was used for the measurement of atomic arsenic, which was excited at 197.2 nm and was detected at 249.6 nm. Results showed that the morphology of the particles varied with the flame temperature and with the chromium source. The particles were characterized by porous structures, cenospheres and agglomerated dense particles when chromium nitrate solution was added to the flames. At low to moderate temperatures, porous sintered cenospheric structures were formed, in some cases with a blow hole. At higher temperatures, an agglomerated cluster which was composed of loosely sintered submicron particles was observed. It was also found that the emission of Cr(VI) from the undiluted $H_2$ flame was more than 10 times larger than in the 50% $H_2$ / 50% $N_2$ flame on a mass basis. Single point LIF measurement of atomic arsenic indicated that arsenic exist only in the low temperature, fuel rich region.

• 에너지공학
• /
• 제10권4호
• /
• pp.379-386
• /
• 2001

본 연구는 산업용 고부하 버너연소에서의 NO$_{x}$ 저감에 관한 실험적 연구이다. 본 연구에서는 NO$_{x}$의 정량적 농도 분포 측정을 위하여 레이저 유동 형광법을 사용하였다. XeCL 엑시머 레이저를 사용하여 NO A-X (0, 0) 진동밴드를 226 nm로 여기하였다. 또한 P$_{21}$+Q$_1$(14.5)/R$_{12}$+Q$_2$(20.5)/P$_1$(23.5) 전이를 여기라인으로 하였으며 다른 간섭의 영향을 최소화 하였다. 본 실험에서 이중선회 확산화염에서의 NO 농도 분포를 측정하였으며, 이 스월버너에서의 화염의 후류에 있어서 NO 농도는 1차/2차 공기비가 증가할 때 감소함을 알수 있었다.

• 한국연소학회지
• /
• 제7권4호
• /
• pp.1-9
• /
• 2002

The morphology of deposits on $15-{\mu}m$ thin SiC filaments has been investigated with SEM and compared with UV-excited laser induced broadband fluorescences in co-flowing, propane laminar diffusion flames in a reduced oxidizer environment. The homogeneous morphology of droplet-like deposits inner flame zone and the agglomeration of condensed-phase deposits and the transition to soots from grown up droplet-like precursors with approaching the flame surface can be observed in a barely sooting flame. The average size of the mature soots deposited in the luminous flame edge is scarcely dependent on their axial position in a confined flame under reduced oxidizer condition. A double structure of PAH fluorescence is observed in near-extinction flames with further decreasing of oxidizer. A comparison of the PAH fluorescence with the morphologies of deposits indicates that appearance of the "dark" hollow zone is caused by a decreased number density of developed liquid-phase large molecules and the outer weak fluorescence zone is caused by the diffusion of gas-phase small molecules.

• 한국응용과학기술학회지
• /
• 제23권4호
• /
• pp.340-346
• /
• 2006

The influences of fluorescence, scattering, and flocculation in turbid material by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by the spectroscopy of laser induced fluorescence (LIF). The effects of optical properties in scattering media have been found by the optical $parameters({\mu}_s,\;{\mu}_a,\;{\mu}_t)$. Flocculation is an important step in many solid-liquid separation processes and is widely used. When two particles approach each other, interactions of several colloid particles can come into play which may have major effect on the flocculation and LIF process, The value of scattering coefficient ${\mu}_s$ is large by means of the increasing particles of scatterer it has been found that the slope decays exponentially as a function of distance from laser source to detector. It may also aid in designing the best model for oil chemistry, biopharmaceutical products, laser medicine and application of medical engineering on LIF and coagulation in particle transport mode.

• 한국약용작물학회지
• /
• 제10권4호
• /
• pp.237-242
• /
• 2002

It was found that the purified extract from A. gigas Nakai (polysaccharide, M.W., 25 kD) controled differentiating human ES cells. Its optimal supplementation concentration was decided as 0.8 $({\mu}g/ml)$ to efficiently control the differentiation. It also enhanced the cell growth, compared to the control. However, most widely used and commercially available differentiating agent, Leukemia Inhibitory Factor (LIF) negatively affected on the cell growth even though it controls the differentiation of ES cells, down to 40-50 % based on morphological observation and telomerase activity. It was presumed that the extract first affected on cell membrane and resulted in controlling signal system, then amplify gene expression of telomere, which enhanced the telomerase activity up to three times compared to the control. LIF only increased the enzyme activity up to two times. It was confirmed that the extract from A. gigas Nakai could be used for substituting currently used differentiation controlling agent, LIF from animal resources as a cheap plant resource and not affecting the cell growth. It can broaden the application of the plants not only to functional foods and their substitutes but also to fine chemicals and most cutting-edge biopharmaceutical medicine.

• Journal of Mechanical Science and Technology
• /
• 제15권12호
• /
• pp.1808-1815
• /
• 2001

The characteristics of a pulsed plasma jet originating from an electrothermal capillary discharge have been investigate using laser-induced fluorescence (LIF) measurement. Previous emission measurements of a 3.1 kJ plasma jet show trial upstream of the Mach disk the temperature and electron number density are about 14,000 K and and 10$\^$17/ cm$\^$-3/, while downstream of the Mach dick tole values are about 25,000 K and 10$\^$18/ cm$\^$-3/, respectively. However, these values are barred on line-of-sight integrated measurements that may be misleading. Hence, LIF is being used to provide both spatially and temporally resolved measurements. Our recent work has been directed at using planar laser-induced fluorescence (PLIF) imaging of atomic copper in the plasma jet flow field. Copper is a good candidate for PLIF studies because it is present throughout the plasma and has electronic transitions that provide an excellent pump-detect strategy. Our PLIF results to date show that emission measurements may give a misleading picture of the flow field, as there appeals to be a large amount of relatively low temperature copper outside the barrel shock. which may lead to errors in temperature inferred from emission spectroscopy. In this paper, the copper LIF image is presented and at the moment, relative density of atomic copper, which is distributed in the upstream of the pulsed plasma jet, is discussed qualitatively.