• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.253-259
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• 2006

The effect of DC electric fields on the flame extinction was investigated experimentally in counterflow configurations for the methane/oxygen/nitrogen diffusion flame. The electric fields was applied by connecting the high voltage and ground terminals to the upper and lower burners, respectively. In case of having electric fields, several modes of flame extinction was observed according to the electric field intensity and strain rate defined by the exit velocity. To visualize and characterize the flame structure and intensity, planar LIF technique was adopted for OH radicals. Consequently, several length scales, including the flame width, thickness, and height from the burner tip, were introduced to explain the various flame behaviors and to characterize the flame extinctions. It was found that the variation of flame width and the chemical reaction are strongly related to a critical electric field intensity, thus the various modes of diffusion flame extinction could be observed due to the electric fields.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.23-32
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• 1997

Characteristics of the lifted flame which is generated by issuing of the fuel through the miniature nozzle, d=0.164 mm, are studied using the planar laser induced fluorescence technique. OH radical is excited on the $Q_1$(8) line of the $A^2{\Sigma}\ ^+{\leftarrow}\ X^2{\prod}$ (1,0) band transition(283.55 nm) and LIF signals are captured at the bands of (0,0) and (1,1) transition(306-326 nm) using the filters and ICCD camera. Hydroxyl radical(OH) profile for nozzle attached flame shows that OH radical populations at the flame sides and flame tip are larger than those at the base. But for the lifted flame (tribrachial flame) case, those are larger at the flame base than at the flame tip and flame sides. The OH radical is more dense near the center line of flame base at the blowing out. This fact proves the Chung and Lee's blowout theory - blowout occurs when the flame is anchored at the flame axis.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.95-95
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• 2016

반도체 및 디스플레이 공정용 플라즈마 장치에서 플라즈마 변수를 측정하기 위한 방법들이 많이 개발되어 왔다. 전자 밀도와 온도는 정전 탐침이나 컷오프 프로브 등을 사용하여 활성종이나 중성종에 비해 상대적으로 쉽게 측정할 수 있고, 활성종과 중성종은 LIF (Laser Induced Fluorescence) 방법, OES (Optical Emission Spectrometry) 방법, 그리고 QMS (Quadrupole Mass Spectrometry) 방법 등을 이용하여 측정할 수 있으나 절대적인 크기를 측정할 수 있는 경우는 제한적인 것으로 알려져 있다. 이러한 문제를 극복하기 위해 측정한 전자 밀도와 전자 온도를 기반으로 하여 고려되는 종들의 밀도를 계산할 수 있는 프로그램도 제작된 바 있다. 개발된 프로그램의 입력 값으로 사용되는 플라즈마 화학반응 데이터베이스는 계산 결과의 정확성과 밀접한 관계가 있으며, 이런 이유로 신뢰성 높은 데이터베이스를 확보하기 위한 연구도 진행되었다. 개발된 프로그램을 이용하여 계산한 플라즈마 변수의 장비 변수에 대한 의존성이 진단 데이터와도 잘 부합하는 것으로 확인되었다.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.241-246
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• 2001

Vortices terminating at free surface have been investigated extensively. Most of investigations, however, are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LIF technique are discussed for the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.3
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• pp.365-370
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• 2004

Simultaneous measurement with PLIF(Planar Laser-Induced Fluorescence) and Stereo-PIV(Stereo Particle Image Velocimetry) was performed to investigate the structural characteristics of flow field in Rushton Turbine Mixer. Instantaneous 3D velocity fields are measured by two 2K${\times}$2K CCD cameras focused on an object plane with the angular displacement methods while the concentration fields are obtained through the measurement of the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. Finally, the spatial structures of turbulent flow around Rushton turbine were identified by the calculation of synchronized data of the velocity field and concentration field.

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.234-234
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• 2004

수정란이식 기술이 활성화되고, 한우의 가격이 상승하여, 젖소에 한우 체외수정란이식이 성행하고 있으나, 수정란이식에 의한 수태율은 수정란이식의 성과를 내고 있다고 할 정도는 아니다. 쥐, 돼지 및 사람에서 착상에 관련되는 인자에 대한 연구가 활발히 이루어지고 있으며, 가장 착상에 관여를 많이 하고 있는 인자는 LIF, IGF와 TGF-β인 것으로 보고되고 있다. 따라서 본 연구는 임신과 관련된 주요기관인 난관의 상피세포를 체외배양하고, 그때 착상을 유도하는 것으로 알려진 IL-1α와 β를 첨가하여 IGF-I의 생산을 조사하였다. (중략)

• Proceedings of the KSAR Conference
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• 2004.06a
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• pp.235-235
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• 2004

Although studies for important genes concerned in preimplantation stage that encompasses the period from fertilization to implantation were reported for mice and cows, little information relevant to this subject is known in pigs. (omitted)

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.6
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• pp.817-822
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• 2002

Sooting characteristics of counterflow ethylene/propane mixture flames have been experimentally studied to investigate the fuel structure effect on PHM and soot formation. Laser-induced incandescene and laser-induced fluorescene techniques were employed to measure soot volume fraction and polycyclic aromatic hydrocarbon (PAH) concentration, respectively. Importance of $C_{3-}$species on PAH growth as well as the H-abstraction-C$_2$ $H_2$addition (HACA) mechanism has been emphasized, considering that PAH growth rate is greater for with mixed fuel than fer pure fuel flames. It was also confirmed that HACA pathways are the dominant soot growth mechanism. A new PAH growth model including both $C_{2-}$ and $C_{3-}$growth mechanisms is proposed based on the experimental results.

• Journal of Power System Engineering
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• v.15 no.1
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• pp.5-10
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• 2011

The spatial fuel vapor distribution of the homogeneous charge by a 6-hole injector was examined in a optically accessed single cylinder direct injection spark ignition(DISI) engine. The effects of in-cylinder charge motion, and fuel injection pressure, and coolant temperature were investigated using a planar LIF (Laser Induced Fluorescence) technique. It was confirmed that the in-cylinder tumble flow played a little more effective role in the spatial fuel vapor distribution than the swirl flow during the compression stroke at 10 mm and 2 mm planes under cylinder head gasket and the increased fuel injection pressure activated spatial distributions of the fuel vapor. In additions, richer mixtures were concentrated around the cylinder wall by the increase of the coolant temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.7-12
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• 2003

Mixture formation in the cylinder of a lean bum engine has been observed by Laser Induced Fluorescence technique. XeCl laser (308nm) was used to produce a laser sheet. 3-pentanone has been added to iso-octane fuel to produce fluorescence, the intensity of which is proportional to the concentration of the fuel. The laser sheet was introduced through the piston window and the fuel distribution in the vertical plane was observed through a side window. Comparison has been made for the cases of selected fuel injection timing as 0, 360, 405, and 450 CA. For the case of 0 and 360 CA injection, uniform fuel distribution in the combustion chamber has been obtained at the ignition time which is favorable for the high load mode. And the late injection cases, 405 and 450 CA, revealed the stratified formation of rich mixture around the spark plug. That extends the lean misfire limit and reduces cyclic variation in the low load mode.