• Journal of Mechanical Science and Technology
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• 제16권7호
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• pp.999-1008
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• 2002

The spray structures and distribution characteristics of liquid and vapor phases in non-evaporating and evaporating Gasoline Direct Injection (GDI) fuel sprays were investigated using Laser Induced Exciplex Fluorescence (LIEF) technique. Dopants were 2% fluorobenzene and 9% DEMA (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to study internal structure of the spray, droplet size and velocity under non-evaporating condition were measured by Phase Doppler Anemometry (PDA). Liquid and vapor phases were visualized at different moments after the start of injection. Experimental results showed that the spray could be divided into two regions by the fluorescence intensity of liquid phase: cone and mixing regions. Moreover, vortex flow of vapor phase was found in the mixing region. About 5㎛ diameter droplets were mostly distributed in the vortex flow region. Higher concentration of vapor phase due to vaporization of these droplets was distributed in this region. Particularly, higher concentration of vapor phase and lower one were balanced within the measurement area at 2ms after the start of injection.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.96-104
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• 2001

The present study experimentally investigates the concentration distribution of liquid and vapor phase with different injection timings in the in-cylinder flow field of a optically accessible engine. The conventional MPI, DOHC engine was modified into DI gasoline engine. The images of liquid and vapor phases in the motoring engine were captured by using exciplex fluorescence method. Dopants used in this study were 2% fluorobenzene and 9% DEMA(diethyl-methyl-amino) in 89% solution of hexane by volume respectively. Two dimensional spray fluorescence images of liquid and vapor phases were acquired to analyze spray behaviors and fuel distribution in the in-cylinder flow field. Measurements were carried out fur four different injection timings, namely BTDC 270$^{\circ}$, 180$^{\circ}$, 90$^{\circ}$, and 50$^{\circ}$. Experimental results indicate that behaviors and distribution of vapor phase were largely affected by in-cylinder tumble flow, and mixture formation process was also greatly affected by in-cylinder flow at early injection mode and by ambient pressure at late injection mode.

• 대한기계학회논문집B
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• 제25권6호
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• pp.868-875
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• 2001

The objective of this study is to investigate the average droplet size distributions of a GDI spray by simultaneous fluorescence/scattering image technique. GDI engine is recently very popular because of high engine efficiency and low emissions. However, the injectors must have good spray characteristics because the fuel is directly injected into the cylinder. The fuel mixtures used in this study were 2% of fluorobenzene, 9% of DEMA(diethyl-methyl-amine) and 89% of hexane by volume. The system for obtaining 2-D fluorescence/scattering images of fuel spray was constituted of a laser sheet, a doubling prism, optical filters, and an ICCD camera. Using the ratio of the fluorescence to the scattering intensities, SMD distributions were obtained. SMD measured by the technique was compared with that obtained by PDA. It was found that average droplet size was bigger at spray center in the early stage of injection and at the outer periphery of the spray in the late stage of injection.

• Journal of Mechanical Science and Technology
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• 제14권10호
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• pp.1143-1150
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• 2000

The effects of ambient conditions on vaporizing sprays from a high-pressure swirl injector were investigated by an exciplex fluorescence method. Dopants used were 2% fluorobenzene and 9% DEMA (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to examine the behavior of liquid and vapor phases inside of vaporizing sprays, ambient temperatures and pressures similar to engine atmospheres were set. It was found that the ambient pressure had a significant effect on the axial growth of spray, while ambient temperature had a great influence on the radial growth. The spatial distribution of vapor phase at temperatures above 473K became wider than that of liquid phase after half of injection duration. From the analysis of the area ratio for each phase, the middle part (region II) in the divided region was the region which liquid and vapor phases intersect. For liquid phase, fluorescence-intensity ratio was greatly changed at lms after the start of injection. However, the ratio of vapor phase was nearly uniform in each divided region throughout the injection.

• 대한기계학회논문집B
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• 제25권5호
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• pp.688-696
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• 2001

Vaporizing characteristics of two GDI injectors with different spray angles were investigated using exciplex fluorescence method. Injector I has narrower spray angle, while injector II has wider one. The exciplex system of fluorobenzene and DEMA in a non-fluorescing base fuel of hexane was employed. In quantifying concentration of fuel vapor, quenching of concentration and temperature was corrected. Droplet size and velocity were also measured by PDPA under non-vaporizing condition. From obtaining the images of liquid and vapor phases, vaporizing GDI sprays could be divided as two regions: cone and mixing regions. For injector I, vortex region was not developed. High concentration of fuel vapor due to vaporization of many fine droplets was distributed near the spray axis. For injector II, droplets with the diameter of about 10 $\mu$m were distributed in the vortex region. The vortex region had high concentration of fuel vapor due to vaporization of these droplets. Particularly, higher and lower concentrations of fuel vapor were balanced at 2ms after the start of injection for injector II.

• 동의생리병리학회지
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• 제19권4호
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• pp.1027-1031
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• 2005

In the present study, wogonin, a major flavone isolated from Scutellaria Radix were examined for its imunosuppressive activity on the 2,4-dinitro-fluorobenzene (DNFB)-induced delayed type hypersensitivity (DTH) in C3H/HeN mice. This compound inhibited selectively $TNF-\alpha$ and IL-4, but not IL-6, IL-10 and $IFN-\gamma$ on DNFB-induced Th1 and Th2 cytokines in a concentration-dependent manner. Interestingly, this compound increased the expression of heme oxygenase-1 (HO-1) in a concentration-dependent manner The above results reveal that wogonin possesses anti-inflammatory, humoral and cellular immunomodulatory, and stress reducing activities on the DNFB-induced DTH in mice and these properties may contribute to the anti-atopic dermatitis activity of Scutellaria Radix.

• 사상체질의학회지
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• 제26권2호
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• pp.180-193
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• 2014

Objectives The present study was carried out to investigate effects of HBPDS on allergic contact dermatitis (ACD) induced by 2,4-Dinitro-1-fluorobenzene (DNFB) in mice. Methods In this experiment, effects of HBPDS on body weights, skin thicknesses, skin weights, histopathological changes, clinical aspects, erythema index, melanin index, production levels of cytokines in ACD mice were investigated. In addition, effects on proliferation rates, release of ${\beta}$-hexosaminidase and histamine were also investigated in vitro. Results & Conclusions 1) HBPDS inhibited enlargement of skin thickness and weight significantly (P < 0.05). 2) HBPDS treatment prevented spongiosis, edema and immune cell infiltrations. 3) Erythema, desquamation and keratosis were diminished by oral administration of HBPDS. 4) Production levels of TNF-alpha and IFN-gamma in serum were decreased by HBPDS treatment in vivo. 5) More than 200 ${\mu}g/ml$ of HBPDS treatment decreased ${\beta}$-hexosaminidase release and more than 400 ${\mu}g/ml$ of HBPDS treatment also decreased histamine release in vitro.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.82-89
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• 2005

This study was performed to investigate the behavior and spatial distribution of fuel mixtures with different wall angle and diameter of piston cavity in a DI gasoline engine. The spatial distribution of fuel mixtures after impingement of the spray against a piston cavity is one of the most important. factors for the stratification of fuel mixture. Thus, it is informative to understand in detail the behavior and spatial distribution of fuel mixtures after impingement in the cavity. Two dimensional spray fluorescence images of liquid and vapor phase were acquired to analyze the behavior and distribution of fuel mixtures inside cylinder by exciplex fluorescence method. The exciplex system of fluorobenzene/DEMA in non-fluorescing base fuel of hexane was employed. Cavity wall angle was defined as an exterior angle of piston cavity. Wall angles of the piston cavity were set to 30, 60 and 90 degrees, respectively. The spray impinges on the cavity and diffuses along the cavity wall by its momentum. In the case of 30 degrees, the rolling-up moved from the impinging location to the round and fuel-rich mixture distributed at periphery of cylinder. In the case of 60 and 90 degrees, the rolling-up recircurated in the cavity and fuel mixtures concentrated at center region. High concentrated fuel vapor phase was observed in the cavity with 90 degrees. From. present study, it was found that the desirable cavity wall angle with cavity diameter for stratification in a Dl gasoline engine was demonstrated.

• 한국식품과학회지
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• 제33권1호
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• pp.146-148
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• 2001

5가지 식용식물인 신이(Flos magnoliae), 지실(Poncirus trifoliata), 시호(Bupleurum falcatum), 황금(Scutellaria baicalensis), 및 오미자(Schisandra chinensis)의 열수 추출물(10 mg/20 g B.W.)이 제IV형 알레르기 반응에 미치는 억제효과를 관찰하기 위하여 DNFB로 감작된 6주령의 웅성 BALB/C mouse에 1, 2차 시료를 투여한 후, 유도된 접촉성 피부염에 의한 부종도를 측정하였으며 대조 약물로는 cyclosporin(0.005 mg/20 g B.W)을 사용하였다. DNFB의 피부염증반응에 대한 귀 두께 측정은 1차 감작에서 황금, 오미자, 지실 군이 대조 군에 비하여 유의한 감소를 나타냈고(p<0.05), 약물 대조군인 cyclosporin과 같은 억제효과를 보였다. 시호, 신이 군은 대조 군에 비해 감소하는 경향을 보였으나 유의한 차이는 없었다. 억제 효과는 황금>오미자>지실>시호>신이의 순으로서 황금 군의 활성이 가장 높았다. 2차 감작에서는 오미자, 지실, 황금, 신이 군이 대조 군에 비하여 유의한 감소를 나타냈고 오미자와 지실은 약물 대조군인 cyclosporin과는 유의적인 차이는 없었지만 억제 효과가 더 컸다. 시호군은 대조 군과 유의적인 차이가 없었으며 오미자>지실>황금>신이>시호의 순으로서 오미자 군이 가장 높은 억제효과를 나타냈다.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.3049-3052
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• 2009

Methyl tert-butyl ether (MTBE) is added to gasoline to enhance the octane number of gasoline, tert-butyl alcohol (TBA) is major degradation intermediate of MTBE in environment, and benzene, toluene, ethyl benzene and xylene (BTEX) are also major constituents of gasoline. In this study, a simplified headspace analysis method was adapted for simultaneous determination of MTBE, TBA and BTEX in ground water samples. The sample 5.0 mL and 2 g NaCl were placed in a 10 mL vial and the solution was spiked with fluorobenzene as an internal standard and sealed with a cap. The vial was placed in a heating block at 85 $^{\circ}C$ for 30 min. The detection limits of the assay were 0.01 ${\mu}$g/L for MTBE and BTEX, and 0.02 ${\mu}$g/L for TBA. The method was used to analyze 110 ground water samples from various regions in Korea, and to survey the their background concentration in ground water in Korea. The samples revealed MTBE concentrations in the range of 0.01 - 0.45 ${\mu}$g/L (detection frequency of 57.3%), TBA concentrations in the range of 0.02 - 0.08 ${\mu}$g/L (detection frequency of 5.5%), and total BTEX concentrations in the range of 0.01 - 2.09 ${\mu}$g/L (detection frequency of 87.3%). The developed method may be used when simultaneously determining the amount of MTBE, TBA and BTEX in water.