• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.9-16
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• 2019

The experiment on the liquid jet in crossflow in supersonic BFS (backward-facing step) flow was conducted to investigate the mixing characteristics. The working fluids are nitrogen and water. The shadow graph technique was used to visualize the flow field. Images captured by the high-speed camera were applied to analyze the flow phenomena. The liquid jet was injected at the re-circulation zone created by the supersonic jet flow. Experimental conditions are defined based on the pressure of the nitrogen gas chamber and pressurized liquid tank. In respective cases, the penetration depth of liquid jet and location of the Mach disc were observed to be proportional to the momentum ratio of gas and liquid jets.

• Journal of Acupuncture Research
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• v.27 no.4
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• pp.9-18
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• 2010

Objectives : This study will broaden understanding of acupotomy therapy through comparison of side effects and complication which can be caused by the mechanism of treatment, surgical methods, and procedure by acupotomy therapy and epidural neuroplasty. Moreover, through an in-depth analysis of headache affected by two procedures, this research is supposed to find prospective cures for headache after acupotomy therapy. Methods : To compare acupotomy therapy with epidural neuroplasty this research was done using a comparative analysis eight theses about acupotomy therapy since 1995, as well as eleven theses about epidural neuroplasty since 2000. Other theses and data were used as references in the process of comparative analysis. Results : Acupotomy therapy and epidural neuroplasty, new treatments of damaged discs in the spine and stenosis made in 1990s, have the mechanism of treatment in common in that adhesion, a node or scar caused by the soft tissue damage is removed by putting catheter or acupuncture into the lesions. Epidural neuroplasty has additional injection into the lesions, which is different from acupotomy therapy in the process of surgical procedure. There are various reports of positive effects about curative effect in these two treatments. The two procedures may cause various complications. Headache may be a complication after surgery. The headache after acupotomy therapy is characterized as being an ache in the body, which is similar to that of post-dural puncture headache in the outbreaks and symptom. Headache after percutaneous epidural neuroplasty appears in general, which is similar to a headache as a result of the increased pressure of the brain spinal cord regardless of posture. Conclusions : Although they are alike in the mechanism of treatment, surgical methods and side effects, and complication after they are carried out as a result of analyzing theses related to acupotomy therapy and percutaneous epidural neuroplasty, there is a difference in aspects and mechanism of headaches experienced after the procedure.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.85-87
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• 1990

Silicon nitride film was deposited on a silicon wafer using a laser CVD(LCVD) technique, which is based on direct photolysis of $SiH_4/NH_3$ gas mixture by ArF laser beam(${\lambda}=193\;nm$). The refractive index of deposited SiN film is 1.9 at the temperature of $300^{\circ}C$, pressure of 5 torr. The breakdown field strength of LCVD SiN film was 10MV/cm. In IR spectrum, the absorption peak of Si-H, N-H, and Si-N is detected and it is shown that hydrogen is included in SiN film. From analysis of absorption band. it is calculated that density of Si-H, N-H bond is higher than $5{\times}10^{22}cm^{-3}$. LCVD MIS capacitor and PECVD MIS capacitor have injection-type hysteresis but it is known that hysteresis loss of LCVD MIS capacitor is smaller than that of PECVD MIS capacitor. It means that Interface state density of LCVD capacitor is smaller than that of PECVD capacitor. In addition, the flatband voltage($V_{FB}$) of LCVD is smaller than that of PECVD capacitor. And it means that fixed charged density($Q_{FIX}$) of LCVD capacitor is smaller than that of PECVD MIS capacitor.

• Journal of Biomedical Engineering Research
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• v.16 no.2
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• pp.209-216
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• 1995

Recently, a new tailored RF gradient echo (TRFGE) sequence was reported. This technique not only enhances the magnetic susceptibility effect but also allows us to measure local changes in brain oxygenation. In this study, a phantom and cat brain experiments were performed on a 4.7 Tesla BIQSPEC (BRUKER) instrument with a 26 cm gradient system. We have demonstrated that the signal intensity (SI) of the TRFGE sequence varies according to the concentration of susceptibility contrast agent. Three capillary tubes with different concentrations of Gd-DTPA (0.01, 0.05, 0.1 mMOI/l) were placed at the middle of a cylindrical water phantom. Using both TRFGE and conventional gradient echo (CGE) sequences, phantom images of the slices which contain all three tubes were obtained. For the animal experiment, cats were anesthetized and ventilated using halotane (0.5%) and a $N_2O/ O_2$ mixture (2:1), and blood pressure and heart rate were monitored and kept normal. For the observation of tue first pass of Gd- DTPA, imaging was started at t = 0. At t = 8 ~ 12s, 0.2 mMol/Kg Gd-DTPA was manually injected in the femoral vein. The imaging parameters were TRITE = 25/10 msec, flip angle = $30^{\circ}$, FOV = 10cm, image matrix size = $128{\times}128$ with 64 phase encodings and the image data acquisition window was 10 msec. SI-time curves were then obtained from a series of 30 images which were collected at 2 sec intervals using both CGE and TRFGE pulse sequences before, during, and following the contrast injection.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.5
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• pp.626-639
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• 2003

Statement of problem : Recently, in attempts to reinforce the acrylic resin and to reduce the polymerization shrinkage, it has been reported that adding vinyloligo-silsesquioxane (vinyl-POSS) to PMMA significantly compensates for polymerization shrinkage and somewhat increases the fracture resistance. Purpose : There haven't been any studies on abrasion that can affect the adaptation of the denture in long-term use. In this study abrasion resistance was compared between acrylic resin with vinyl-POSS and commercialized acrylic resin for denture base. In addition, the difference in abrasion resistance according to molding methods was compared. Material and method : Using PaladentR 20 including vinyl-POSS. PaladentR 20, Lucitone 199R, SR IvocapR, denture bases were fabricated using compression molding technique and continuous-pressure injection technique. Surface hardness and abrasion were measured for each group, and the worn surfaces were observed under a scanning electron microscope. Results : 1. When surface hardness was measured for each material and molding technique, there was no statistically significant difference among the materials. (p<0.05) 2. When same denture base material and molding technique were used, the abrasion due to toothpaste solution was 5 times as severe as the abrasion due to soap solution. 3, When toothpaste solution was used, the abrasion decreased in the order of PaladentR20, PaladentR 20 including vinyl-POSS, SR IvocapR, and Lucitone 199R. However statistically significant difference was seen only among PaladentR 20, SR IvocapR, and Lucitone 199R. (p<0.05). 4. When soap solution was used, the abrasion was more severe in PaladentR 20 and including vinyl-POSS PaladentR 20 groups than in SR IvocapR and Lucitone 199R groups. (p<0.05). Conclusion : Addition of vinyl-POSS doesn't improve the abrasion resistance, and the abrasion resistance was similar to those of existing materials. Additional studies under different conditions are needed. For clinical application of vinyl-POSS, further investigations with different requirements and conditions are necessary.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1022-1027
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• 2011

A diesel engine works in high compression ratio due to injection of diesel fuel after compression of air. Therefore the engine has a high thermal efficiency, while nitrogen oxide is produced a lot in high flame temperature regions. In order to solve the problem this study HHO gas is added into the intake air of the industrial diesel engine. The test conditions are loads of 0%, 50% and 100% and engine speeds of 700 to 1900 rpm. The results show the maximum torque and pressure is increased, fuel consumption, smoke and CO emissions are decreased and NOx emission is remained at same level.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.130-136
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• 2011

This study describes the effect of EGR rate on the combustion and emissions characteristics of a four cylinder CRDI diesel engine using biodiesel (soybean oil) blended diesel fuel. The test fuel is composed of 30% biodiesel and 70% ULSD (ultra low sulfur diesel) by volumetric ratio. The experiment of engine emissions and performance characteristics were performed under the various EGR rates. The experimental results showed that ignition delay was extended, the maximum combustion pressure and heat release gradually were decreased with increasing EGR rate. Comparing biodiesel blended fuel to ULSD, the injection quantity of biodiesel blended fuel was further increased than ULSD. The emission results showed that $NO_x$ emission of biodiesel blended fuel becomes higher according to the increase of EGR rate. However, in the case of biodiesel blended fuel, HC, CO and soot emissions were decreased compared to ULSD.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.7
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• pp.619-625
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• 2015

Swirl injectors are widely used for Liquid Rocket Engine(LRE) as fuel injection system and following researches are also being carried out throughout the world. Especially, solving combustion instability problem is essential for every type of LREs. In this study, cold test was carried out for open type swirl injector as a fundamental research to solve combustion instability problem. Pressure fluctuation was applied to the inlet flow coming into the injector and the following response characteristics were observed. The effect of swirl chamber geometry was also studied by changing both swirl chamber length and diameter.

• Journal of Korean Biological Nursing Science
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• v.16 no.3
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• pp.182-191
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• 2014

Purpose: The aim of this study was to identify necessary emergency treatment and nursing activities for severe trauma patients according to elapsed time and vital signs. Methods: A survey was conducted with 121 patients over 15 points ISS on EMR from June 1, 2011 to May 31, 2012. Collected data were analyzed with descriptive statistics, applying McNemar's test using SPSS 12.0. Results: Almost all of the subjects were men and the mean age was 46.9. Run-time for primary diagnosis, treatment decision, and leaving for the hospital room was 0.19, 4.36, and 4.21 hours, respectively, and stayover time was 9 hours. Regardless of vital signs, emergency treatments involving ambu-bagging, intubation, ventilator, and central vein catheterization insertion were offered within an hour. Central venous pressure, Foley catheter/Levin tube preparation and maintenance were performed in cases of unstable vital sign patients within an hour. Unrelated to vital signs, nursing activities for consciousness assessment, skin assesment and wound care, bed sore/fall down assesment and care, intravenous injection insertion and maintenance were conducted for all severe trauma patients within an hour. Foley catheter/Levin tube drainage care was performed for patients who had unstable vital signs within an hour. Conclusion: Emergency treatment and nursing activities for severe trauma patients were specific according to elapsed time and vital signs.

• Journal of Korean Neurosurgical Society
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• v.58 no.1
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• pp.1-8
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• 2015

Treatment of Leptomeningeal carcinomatosis (LMC) from solid cancers has not advanced noticeably since the introduction of intra-cerebrospinal fluid (CSF) chemotherapy in the 1970's. The marginal survival benefit and difficulty of intrathecal chemotherapy injection has hindered its wide spread use. Even after the introduction of intraventricular chemotherapy with Ommaya reservoir, frequent development of CSF flow disturbance, manifested as increased intracranial pressure (ICP), made injected drug to be distributed unevenly and thus, the therapy became ineffective. Systemic chemotherapy for LMC has been limited as effective CSF concentration can hardly be achieved except high dose methotrexate (MTX) intravenous administration. However, the introduction of small molecular weight target inhibitors for primary cancer treatment has changed the old concept of 'blood-brain barrier' as the ultimate barrier to systemically administered drugs. Conventional oral administration achieves an effective concentration at the nanomolar level. Furthermore, many studies report that a combined treatment of target inhibitor and intra-CSF chemotherapy significantly prolongs patient survival. Ventriculolumbar perfusion (VLP) chemotherapy has sought to increase drug delivery to the subarachnoid CSF space even in patients with disturbed CSF flow. Recently authors performed phase 1 and 2 clinical trial of VLP chemotherapy with MTX, and 3/4th of patients with increased ICP got controlled ICP and the survival was prolonged. Further trials are required with newly available drugs for CSF chemotherapy. Additionally, new LMC biologic/pharmacodynamic markers for early diagnosis and monitoring of the treatment response are to be identified with the help of advanced molecular biology techniques.