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UV광 측정용 아조벤젠 코팅된 FBG의 열적 효과 제거 및 파장 의존성에 대한 연구
최동석,김현경,안태정,Choi, Dong-Seok,Kim, Hyun-Kyoung,Ahn, Tae-Jung 한국광학회 2011 한국광학회지 Vol.22 No.2
본 논문에서는 ultraviolet (UV) 광의 세기를 원격으로 측정하기 위한 아조벤젠 (azobenzene) 코팅된 fiber Bragg grating (FBG)를 구현하였다. 아조벤젠 폴리머는 UV 광에 의해서 탄성이 변화하여 FBG의 코어 격자의 주기 변화를 유도하여 중심파장을 이동시킨다. 중심파장의 이동은 UV 광과 UV 이외의 파장대역의 빛에 의해서 복합적으로 발생하는데 중심파장의 이동량은 약 0.18 nm 이다. 측정의 정확성을 향상시키기 위해서 광원의 복사열에 의한 중심파장의 이동을 열차단 필터(thermal filter)를 사용하여 제거한 결과 중심파장의 이동량은 약 0.06 nm로 다소 감소하였지만 분석 결과 열에 의한 이동량이 충분히 제거된 것을 확인하였다. 또한 서로 다른 방법인 열경화법과 UV 경화법으로 각각 제작된 아조벤젠 폴리머를 이용하여 아조벤젠 코팅 FBG를 제작하였고, 각 제조법에 따른 UV센서로서의 적합성을 확인하였다. 몇 개의 밴드패스 필터(band pass filter)를 사용하여 파장에 대한 민감도를 측정한 결과, 단위 UV 세기당 중심파장의 이동량은 370nm 파장 밴드에서 가장 큰 값인 0.029로, 단파장 영역에서 반응성이 우수하다는 사실을 확인 하였다. 아조벤젠 폴리머의 흡수 스펙트럼과 아조벤젠 코팅 FBG의 파장 의존도가 서로 잘 일치하는 것을 확인하였다. In the paper, we have demonstrated an azobenzene-coated fiber Bragg grating (FBG) for monitoring ultraviolet light (UV) intensity in remote measurement. The elasticity of the coated azobenzene polymer is changed by the UV light, which induces a center wavelength change corresponding to the change of the FBG's grating period. The wavelength shift resulting from both UV light and other light with the wavelength out of the UV range was about 0.18 nm. In order to improve the accuracy of the measurement, the center wavelength shift caused by radiant heat of the light source was sufficiently removed by using a thermal filter. The amount of the center wavelength shift was consequently reduced to 0.06 nm, compared to the result without the thermal filter. Also, the FBGs coated by using azobenzene polymer were produced by two different methods; thermal casting and UV curing. Considering temperature dependence, UV curing is more suitable than thermal casting in UV sensor application of the azobenzene-coated FBG. In addition, we have confirmed the wavelength dependence of the optical sensor by means of four different band pass filters. Thus, we found out that the center wavelength shift per unit intensity is 0.029 [arb. unit] as a maximum value at 370 nm wavelength region and that the absorption spectrum of the azobenzene polymer was very consistent with the wavelength dependence of the azobenzene-coated FBG.
최동석,류경훈,차건종,김덕줄,Choi, Dong-Seok,Ryu, Kyung-Hoon,Cha, Keun-Jong,Kim, Duck-Jool 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.10
High-pressure swirl injectors have usually been employed in Gasoline direct injection engines due to their spray characteristics and the feasibility of their control. Thus the microscopic characteristics of high-pressure swirl spray were investigated by PDA. The correlation between axial and radial velocities and the correlation between droplet size and axial velocity were examined with different axial and radial positions. Two dimensional droplet velocity and its number distribution with size-classified droplets were illustrated. The mean droplet velocity and its SMD were also analyzed at the center of spray, the position having maximum mean axial velocity, and the spray periphery using time dividing method. Finally, the structure of high-pressure swirl spray was presented with the size distribution and velocity profile of droplets.
최동석,김덕줄,고장권,Choi, Dong-Seok,Kim, Duck-Jool,Ko, Chang-Kwon 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.8
The disintegration process of initial spray from high-pressure swirl injector was investigated at different injection pressures. The transient breakup phenomena that were difficult to observe at high injection pressure were easily observed at the low injection pressure of 0.4MPa. The effect of fuel remained inside a nozzle hole volume on the penetration of initial spray was also investigated. The disintegration process of initial spray could be classified four regions: the formation of mushroom shape, the first collision, the second collision, and the development of spray, The liquid film of cup shape was particularly found in the second collision region, and the growth ratio of its length and width at low and high injection pressures were compared.
최동석(DS Choi),김윤하(YH Kim),임종신(JS Lim),송태복(TB Song) 대한산부인과학회 1989 Obstetrics & Gynecology Science Vol.32 No.1
1980년1월부터 1987년 7월까지 만 7년 7개월동안 전남대학병원 산부인과에서 분만하였던 총 8205명의 임산부중 35세이상의 임산부 280명을 조사군으로 하고 동기간에 분만하였던 경우에서 무작위로 추출한 20-30세의 임산부 285명을 대조군으로하여 다음과 같은 결론은 얻었다. 1. 35세이상 임산부의 발생빈도는 전체분만중 3.7%이었으며, 35세이상 초산부의 발생은 전체분만의 0.6%이었다. 2. 산모체중, 고혈압, 태반조기박리 및 제왕절개술은 노령임산부군에서 대조군보다 의의있게 높았고, 임신주수, 진통시간, 전치태반, 요로계감염, 산후출혈, 다태임신 및 조기파막은 두군간에 의의있는 차이가 없었다. 3. 낮은 Apgar점수와 자궁내 태아사망 및 거대아는 노령군에서 의의있게 높았고 태아성비와 태아기형은 두군간에 의의있는 차이가 없었다. 4. 노령임산부군에서의 안 좋은 infant outcome에 대해 산모체중, 고혈압, 또는 태반조기박리는 그 단독으로 통계학적으로 유의성있는 영향을 미치지 않았다. 결론적으로 노령임산부에서의 안 좋은 infant outcome은 산모체중, 고혈압, 또는 태반조기박리의 어떤 한 경우에 의해 영향받지 않았고 이는 아마도 여러 가지 복합적인 것에 의한 것으로 사료되며, 노령임신은 고위험임신으로 간주되어야 하고 철저한 임신 및 분만관리가 필요할 것으로 생각된다. With the changing life patterns for women in current society, there is often a postponement of childbearing . Thus the impact of older maternal age on pregnancy outcome becomes increasingly important . It has been known that pregnancy outcome of women 35 years of age or older are considered to be less favorable. To examine this hypothesis, 280 pregnancy in women whose age was 35 or more years at delivery were compared with 285 pregnancy in women whose age 20 to 30 years at delivery at Department of Obsterics and Gyunecology, Chonnam University Hospital from January 1980 to July 1987. The fetus under 1000 gm was excluded. the results obtained were as follows; 1. Study group was 3.7% of total delivery 8205 cases .Primiparous women were 15% and multiparous women were 85% in the study group . 2. The older women had higher weights. There was also an increased frequency of hypertension, placental abruption and cesarean section in the older women, But gestational age, length of labor , the frequency of placenta previa urinary tract infection postpartum hemorrhage, multifetal pregnancy, preterm delivery, and PROM were not statistically difference between two group . 3. Low Apgar scores, intrauterine fetal death, and macrosomia were more frequency in the older women but there was a no statistically difference between two groups in the fetal sex ratio, fetal anomaly, and LBW infant. 4. There was no infuence in the infant outcomes when women with obesity, placental abruption , or hypertension was exclued from analysis. This investigation indicated that the pregnancy outcomes of women 35 years of age or older are considered to be less favorable than those of younger women. So careful antenatal and intrapartal care should be performed for the old aged pregnancy women.
코팅 형태에 따른 아조벤젠 코팅 FBG 자외선 센서의 특성 연구
최동석 ( Dong Seok Choi ),정회석 ( Hoe Seok Jeong ),김찬영 ( Chan Young Kim ),송일신 ( Il Shin Song ),김현경 ( Hyun Kyoung Kim ),안태정 ( Tae Jung Ahn ) 조선대학교 공학기술연구원 2012 공학기술논문지 Vol.5 No.2
In this study, we have characterized a ultraviolet (UV) sensor based on a fiber Bragg grating (FBG) coated with azobenzene-containing polymer material. The elasticity of the azobenzene polymer as a photo-responsive material that undergoes reversible refractive index change on exposure to ultraviolet light, which induces the center wavelength shift corresponding to the variation of the azobenzene-coated FBG`s period. In comparison with thermal casting method and UV curing method to polymerize the functional material, it turns out that UV curing method is more suitable than thermal curing method for the UV sensors. We prepared an azo-coated FBG attached on slide-glass and made by a homemade Teflon mold. It was found out that azo-coated FBG fabricated by using the Teflon mold is more suitable than the other method for the UV sensors. In order to confirm the reproducibility and reliability of the proposed UV sensor, we repeatedly tested the UV-induced response of the sensor at 60 times for 120 minute.
최동석(D.S.Choi),김덕줄(D.J.Kim),오승묵(S.M.Oh),황의상(E.S.Hwang),정용일(Y.I.Jeong) 한국자동차공학회 1996 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1996 No.6_2
The OH molecule is a highly reactive combustion intermediate and relatively abundant in combustion systems. It also has the availability of convenient UV -laser systems to excite the A²Σ-X²?? electronic transition. The spectroscopic parameters describing this transition are well known. In this research, the OH molecule was measured in the laminar flame burner and constant volume combustion chamber(CVCC) in order to use it as the fundamental data for studying combustion phenomena. The LIF images of the OH molecule in the laminar 리ame burner were caught by using KrF excimer laser and ICCD camera. The natural fluorescence<br/> of OH was also measured by the interference filter(310 nm) and spectrometer in the CVCC at different equivalence ratios.