• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.468-472
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• 1999

평면 레이저 유도 형광법을 사용하여, 가시와 엔진내부에서 연소 과정이 진행되느 동안 OH라디칼 분포에 대한 2차원 영상을 계측하였다. Rayleigh 산란광을 차단하기 위해서 광대역 필터인 UG11을 사용하였으며, OH 형광 영상은 ICCD카메라로 수집하였다. OH라디칼 은 Q1(11)과 P2(8) 파장으로 여기하였다. 엔진 연료로는 iso-octane을 사용하였으며, 이 연료에서는 자체 형광이 발생하지 않았다. 난류를 암시하는 주름진 화염 경계면을 명확하게 관측하였으며, 어떤 영상에서는 화염 섬(flame island)이 나타나기도 한다.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.169-175
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• 1995

레이저 계측기술의 일반적인 장점인 비접촉방식에 의한 측정 가능, 측정의 정밀 정확도 향상, 높은 검지도 등의 장점으로 연소현상을 진단하기 위하여 여러 가지 레이저 게측지술이 사용되고 있다. 레이저를 이용한 연소진단 기술 중 가장 널리 사용되고 있는 CARS, 레이저 형광유도 기술, 축퇴사광파 혼합기술에 대한 연구를 수행하였다. CARS 기술은 관련 측정기술과 실제 화염의 구조를 분석하는 응용연구를 하였으며, 산업적인 응용을 위한 장비를개발하였다. 그리고, 레이저 형광 유도 기술을 적용하여 화염 내부에서의 OH 농도를 측정하였다. 최근 활발히 연구되고 있는 축퇴사광파 혼합기술을 이용한 연소기체 진단법을 연구하기 위하여, 분광기를 구성하고 화염 내에서 OH 농도를 측정하여 레이저 유도형광법으로 측정한 결과와 비교 하여 서로 일치하는 결과를 얻었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.12
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• pp.4044-4052
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• 1996

Planar images of OH and $O_{2}$ with tunable KrF excimer laser which has a) 0.5 $cm^{-1}$ / linewidth, b) 0.5 nm tuning range, c) 150 mJ pulse energy, and d) 20 ns pulse width are obtained to determine spatial distributions of OH and $O_{2}$ in premixed $C_{3}$H$_{8}$ /O$_{2}$ flame. The technique is based on planar laser induced pre-dissociative fluorescence(PLIPF) in which collisional quenching is almost avoided because of the fast pre-dissociation. Dispersed LIPF spectra of OH and $O_{2}$ are also measured in a flame in order to confirm the excitation of single vibronic state of OH and $O_{2}$, OH and $O_{2}$ are excited on the P$_{2}$(8) line of the $A^{2}$.SIGMA.$^{+}$(v'= 3)-X$^{2}$.PI.(v'||'||'&'||'||'quot;= 0) band and R(17) line of the Schumann-Runge band B$^{3}$.SIGMA.$_{u}$ $^{[-10]}$ (v'= 0)- X$^{3}$.SIGMA.$_{g}$ $^{[-10]}$ (v'||'||'&'||'||'quot;= 6), respectively. Dispersed OH and $O_{2}$ spectra show an excellent agreement with simulated spectrum and previous works done by other group respectively. It is confirmed that OH widely distributed around flame front area than $O_{2}$.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2004.11a
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• pp.310-311
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• 2004

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.710-719
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• 1996

Laser applied combustion diagnostic techniques-laser induced fluorescence (LIF) and coherent anti-Stokes Ramann spectroscopy (CARS)-are demonstrated. The profiles of hydroxyl radical (OH) and temperature in the counterflow burner are measured and compared with the numerical results. OH radical is excited on the Q$_1$(6) line of the $A^2$$\sum^+$$\leftarrow$$X^2{\prod}$(1, 0) band transition (281.1 nm) and LIF signal is measured at the the bands of (0, 0) and (1, 1) transition (306~326 nm). Absolute OH radical is obtained by using the laser absorption technique. The quenching effects are considered. Temperature is measured using broadband CARS system. Two dimensional OH radical profile is also obtained. The profiles of OH radical and temperature are found to agree well with those of numerical calculation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.11
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• pp.1393-1402
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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.$^{+.leq.X2}$ .PI.(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. axis.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.3
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• pp.169-180
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• 2002

Rayleigh scattering and laser induced predissociative fluorescence are used to obtain two-dimensional images of temperature and species concentration in a laminar non-premixed flame of a diluted hydrogen jet. Rayleigh scattering cross-sections are experimentally obtained at 248nm. Planar images of OH and $O_2$ with tunable KrF excimer laser which has a) $0.5cm^{-1}$ linewidth, b) 0.5nm tuning range, c) 150mJ pulse energy, and d) 20ns pulse width are obtained to determine spatial distributions of OH and $O_2$. The technique is based on planar laser induced predissociative fluorescence (PLIPF) in which collisional quenching is almost avoided because of the fast predissociation. Dispersed LIPF spectra of OH and $O_2$ are also measured in a flame in order to confirm the excitation of single vibronic state of OH and $O_2$. OH and $O_2$ are excited on the $P_2$(8) and $Q_1$(11) line of the $A^2{\Sigma}^{+}({\nu}^{'}=3)-X^{2}{\Pi}({\nu}^{''}=o)$ band and R(17) line of the Schumann-Runge band $B^{3}{\Sigma}_{u}{^-}(\nu^{'}=0)-X^{3}{\Sigma}_{g}{^-}({\nu}^{''}=6)$, respectively. Fluorescence spectra of OH and Hot $O_2$ are captured and two-dimensional images of the hydrogen flame field are successfully visualized.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.4
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• pp.91-99
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• 1994

Tunable KrF Excimer Laser is used here for measuring OH and $O_2$ density distribustion in an open $H_2$/air premixed flame and in a combustion bomb. Laser Rayleigh Scattering(LRS) and Planar Laser Induced Predissociative Fluorescence(PLIPF) methods are used to obtain two-dimensional images of total and specific densities. Laser Excitation wavelengths are calibrated via flame images and combustion bomb images show good qualitative a greement with theoretical calculation. Furthermore images in a combustion bomb can be developed to study real Spark-Ignition engine combustions. Our experimental images show that there are no more collisional quenching problem at high pressure environment(including atmospheric pressure) using predissociative fluorescence technique. Further development to obtain two-dimensional temperature dustribution is ready to use eventhough it is not reported in this paper.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.51-52
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• 2003

대기 중에서 HOx(OH, H $O_2$) 라디칼은 매우 중요한 산화제로, 대류권내 광화학 반응에 있어 그 역할이 핵심적이라 할 수 있다. 이러한 OH 라디칼의 정확한 농도를 측정하는 것은 대기의 산화능, 기후 변화 및 대기 중의 광화학 반응을 보다 정확히 이해하기 위해 매우 필요한 연구이다. 그러나 OH를 비롯한 HOx 라디컬의 농도 측정은 이들이 라디칼이기 때문에 매우 어려운 것이 사실이다. 즉, 이들은 대기 내에 존재하는 양이 절대적으로 적고 (OH: $10^{6}$molecules cm-$^3$, H $O_2$: $10^{8}$molecules cm-$^3$), 반응성이 커서 수명이 짧기 때문에 측정에 많은 어려움이 따른다. (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.11a
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• pp.319-320
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• 2003

대기 중에서 HOx(OH, H $O_2$) 라디칼은 중요한 산화제로, 대류권내 광화학 반응에서 핵심적인 역할을 한다 이러한 OH 라디칼의 정확한 농도를 측정하는 것은 대기의 산화능력, 기후 변화 및 대기 중의 광화학 반응을 보다 정확히 이해하기 위해 필수적이다. 그러나 OH를 비롯한 HOx 라디컬의 농도 측정은 대기 내에 존재하는 양이 절대적으로 작고 (OH: $10^{6}$molecules $cm^{-3}$, H $O_2$: $10^{8}$molecules $cm^{-3}$), 반응성이 커서 수명이 짧기 때문에 측정에 많은 어려움이 따른다. (중략)