• Journal of ILASS-Korea
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• v.9 no.1
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• pp.21-29
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• 2004

The flow characteristics of a swirl injector were investigated with the variation of the flow condition and geometric dimensions, such as orifice length for considering the viscous effect and tangential entry port area for considering the swirl intensity. The liquid film thickness strongly influencing on the formed drop size of the spray was measured using a new technique. The film thickness measurement technique proposed here, used the attenuation of fluorescence signal near the injector exit. The breakup length that is important for the flame location as well as the spray cone angle which influences on the ignition performance was measured using a backlit stroboscopic photography technique. From the experimental results, it is found that an increase in injection pressure decreased the film thickness and breakup length, and also enlarged the spray cone angle. A decrease in orifice length and tangential entry port area has a similar tendency of thinner film thickness, shorter breakup length and larger spray cone angle. In the present study, we proposed empirical models of the flow characteristics of the swirl injectors.

• Journal of ILASS-Korea
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• v.24 no.4
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• pp.185-193
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• 2019

The effervescent atomizer is one of twin-fluid atomizers that aeration gas enters into bulk liquid and two-phase flow is formed in the mixing section. The effervescent atomizer requires low injection pressure and small amount of aeration gas, as compared to other twin-fluid atomizers. In this study, cold flow test was conducted to investigate the spray characteristics of aerated impinging jets. The present effervescent impinging atomizers were composed of the aerator device and like-on-like doublet impinging atomizer which had different impinging angles. To analyze the spray characteristics such as breakup length and droplet size distribution, the image processing technique was adopted by using instantaneous images at each flow condition. Non-dimensional parameters, induced by the homogeneous flow model, were used to predict the breakup length. The breakup length was decreased with the mixture Reynolds number and impinging angle increasing. The result of droplets showed that the size distribution was axisymmetric about the center of the injector and their diameter tended to decrease with increasing GLR.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.541-548
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• 2014

This study was performed to obtain high conversion efficiency of $C_7H_8$ using non-thermal plasma and metal-supported catalyst. Adsorption-desorption characteristics of toluene was performed using 4A type (Zeolite) filled in a concentration reactor. Through this test, it was found that the concentration reactor has 0.020 g/g of adsorption capacity (at ambient temperature and pressure) and 3,600 ppm of desorption property at $150^{\circ}C$ (with in 20 min). In case of developed catalyst, toluene decomposition rate of Pd-AO (Pd coated catalyst) was better than Pd/Cu-AO and Pd/Ag-AO (Pd/Ag composite metal catalyst). Developed non-thermal plasma system was obtained flame amplification effect using injection process of desorbed tolune, and 98% of removal efficiency.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.5
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• pp.9-17
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• 2008

Pseudo-3D spatial distribution of spray droplets is investigated by using Dual-mode Phase Doppler Anemometry (DPDA) in order to examine the disintegration and spreading behavior of spray exiting from liquid-propellant thruster injector. Spray injected from nozzle orifice with length-to-diameter ratio ($L/d_o$) of 1.67 and under the injection pressure of 27.6 bar is aligned to the vertical. Vertical and horizontal mean velocities of droplets, Sauter Mean Diameter (SMD), and volumetric flux decrease as droplets travel from center/upstream toward outer region/downstream of spray. Although the distribution of spray characteristic parameters is symmetric against the geometric axis of nozzle orifice, their absolute values are asymmetric.

• Natural Product Sciences
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• v.24 no.1
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• pp.36-39
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• 2018

Phytochemical analysis of Boehmeria nivea (Bn) leaves by medium pressure liquid chromatography led to the isolation of a flavonoid glycoside identified by spectroscopic analysis as rutin. The amount of rutin in the leaves of Bn harvested from nine regions in South Korea (Bn 1-9) which were collected on the months of June, July, August, and September was determined by HPLC-UV analysis. A gradient elution program that utilizes a $Discovery^{(R)}$ C18 ($4.6{\times}250mm$, $5{\mu}m$) column and mobile phase composed of 1% acetic acid-water: acetonitrile (90:10 to 60:40 for min) was followed. The injection volume and flow rate were $10{\mu}l$ and 1 mL/ min, respectively. UV detection was set at 350 nm. Results show that Bn-8 harvested in September reported the highest content of rutin among the samples analyzed. This study provides a basis for the optimal harvest time of Bn which maximizes the yield of rutin.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.652-656
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• 2004

Both surface wash and backwash are considered as one of the most important methods that can improve the filtration efficiency in the existing water treatment plant. This study has mainly focused on the improvement of filtering efficiency by controlling surface wash and backwash time, and water level before backwash (when drained up to the trough, when drained up to 10 cm above filter bed, and when drained below 10 cm filter bed). Filtration efficiency was shown a little bit of differences depending on the operating conditions like surface wash injection pressure, the distance control between filter bed and the facility, and the types of surface wash. When the water level before backwash was reached up to 10 cm below filter bed after draining, however, the filtration velocity and the turbidity removal efficiency in the filter bed was improved. When the surface wash followed by backwash is longer, it showed a similar result. Because the proper adjustment of surface washing time makes filtration efficiency higher, therefore, it is necessary to set up the backwash time moderately.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.87.1-87.1
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• 2011

For commercial applications, MEA development must be optimized in order to achieve high performance and low cost. There are many factors that affect the performance of MEA. Especially, the optimization of the method for preparing catalyst layer has great effect on the performance of MEA. Various methods have been used to prepare the catalyst layer of MEA. Among them, spraying method has a merit in that catalysis lay can be prepared with very flexible changes in catalyst layer as well as in the solvent composition of catalyst ink. In addition, in order to reduce the time required for manufacturing catalyst layer, an effort has been made to change the nozzle size and injection pressure of spray system. Further, the operation condition of spray system was changed in various ways in an effort to prepare optimum catalyst layer of MEA. Having optimized the operation condition of spraying system, comprehensive and diverse experiments were carried out concerning various factors that affect the performance of MEA. The present research report describes the results of more sub-categorized and more detailed experiments about the important factors (Nafion$^{(R)}$ ionomer, Relative humidity) which have been shown in previous experiments to exert greater effect on the performance of MEA.

• The Korean Journal of Pain
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• v.8 no.1
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• pp.159-163
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• 1995

Accidental high epidural block is a rare but serious complication. It can result from many factors, which include the volume and concentration of drug, posture, puncture site, age, pregnancy or intra-abdominal mass, and patients' height and weight. We had a case of accidental high epidural block recently. This is a case report which was confirmed by an epiduragram. A healthy 50-year-old woman with a huge uterine myoma was scheduled for a total abdominal hysterectomy under continous epidural analgesia. Epidural catheterization was carried out smoothly. However, an unexpected hypotension was noticed after an epidural injection of 2% lidocaine 25 ml. Thereafter, the patient was intubated and her respiration was controlled during the operation. Using the 5mg of ephedrine, her blood pressure and pulse were well maintained. The scheduled operation was carried out for one hour uneventfully, but after the operation, she felt paresthesia on her hands in the recovery room. To differentiate between the high epidural and the subdural blocks. We injected 5 ml of a water soluble Niopam 300 through the catheter postoperatively. It was observed on the epiduragram that the catheter was placed in the epidural space. It was suggested that the high epidural block was induced from the widespread diffusion through the narrowed epidural space due to the engorgement of the epidural venous plexus by the patient's huge uterine myoma.

• The Korean Journal of Pain
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• v.8 no.1
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• pp.43-50
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• 1995

The purpose of this study was to compare postoperative analgesic effect according to intravenous doses of ketorolac. The ninety-eight adult patients, scheduled for elective surgery under general anesthesia, were randomly assigned to receive saline or one of the five doses of ketorolac (10, 15, 30, 45, 60mg). After recoverg from anesthesia, saline or ketorolac was injected intravenously, and the visual analogue score, sedation secore, mean blood pressure, heart rate, and the incidence of nausea and vomiting were measured 30 minutes, 1 hour and 2 hours the injection. Saline or 10 mg of ketorolac had no postanalgesic effect. Above 15 mg of ketorolac had analgesic effect, but this analgesic effect was not increased with increasing doses of ketorolac (30, 45, 60 mg). Any side effects (nausea, vomiting, excessive sedation, cardiopulmonary depression, and renal and hematologic adverse events) was not observed associated with ketorolac administration. These results suggested that 15 mg of ketorolac is the most reliable dose for postoperative anlgesia in intravenous administration.

• The Korean Journal of Pain
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• v.1 no.1
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• pp.98-102
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• 1988

In order to control the pain after hemorrhoidectomy and anal fistulectomy, 6 mg of 0.5% hyperbaric tetracaine without(control, group I) or wilt 0.3 mg(group II) or 0.5 mg (group III) of 0.1% morphine was injected with a 22 gauge spinal needle into the subarachnoid space through L 3-4 interspace of patients in lateral position. About 30 minutes in Fowler' sposition after injection, operation was performed in lithotomy position. All the patients who ha4 morphine showed remarkable relief of postoperative pain for an average of 27 hours. However, the dosage(0.3 or 0.5 mg) of morphine administered did not affect the duration of pain relief. Blood pressure, pulse rate and pupil size were unchanged in all patients. Dysuria after block developed for on average of 5,6, 13.2 and 14.6 hours in group I, II and III respectively. Most of these cases required urethral catheterization. Minor complications such as nausea, vomiting, itching, fever, burning sensation and paresthesia were observed 16.7, 20 and 20% of cases in group I, II and III respectively; however, no treatment was required.