• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.3
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• pp.263-270
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• 2015

Using Diesel-Water Emulsion fuel in commercial diesel engine can reduce NOx and soot when it is injected through the injector. Because water in Diesel-Water Emulsion fuel is vaporized ahead of diesel particle and it cause decrease of combustion temperature. Furthermore, research about the possibility of applicating Diesel-Water Emulsion fuels to commercial diesel engine is demanded in order to prove that Diesel-Water Emulsion fuel is able to apply commercial diesel engine without any replacement of equipments. This research analyzed applicable possibility of Diesel-Water Emulsion fuels to commercial diesel engine's fuel injection system refering injection and spray characteristics. In this research, there are 3 experiments, that is injection quantity, spray visualization, and injection rate. Diesel-Water Emulsion fuel has less injection quantities compared to diesel fuel, and spray penetration length is more longer than diesel. Furthermore, emulsion fuels have less dispersed than diesel fuel. In conclusion, comparing with diesel fuel with only spray characteristics, Diesel-Water Emulsion fuel has bad effects about dispersion and vaporization.

• Journal of the Korean Society of Combustion
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• v.22 no.3
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• pp.23-28
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• 2017

The fuel and oxidizer mixing process in the shock tube driven section is simulated numerically. The boundary condition is set based on an shock tube experimental condition. The objective is to predict the gas mixing time for experiments. In the experiment, the amount of fuel to be injected is determined in advance. Then, according to duration of fuel injection, 5 cases with the same fuel mass but different fuel mass flow rate are simulated. After fuel is injected into the driven section, the fuel and air will be mixed with each other through convection and diffusion processes. The mixing time is predicted numerically for experiments.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.6
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• pp.145-151
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• 2010

The performance of a direct-injection diesel engine often depends on the strength of swirl or squish, the shape of combustion chamber, the number of nozzle holes, etc. This is natural because the combustion in the cylinder was affected by the mixture formation process. Since the available duration to make the mixture formation of air-fuel is very short, it is difficult to make complete mixture. Therefore, an early stage of combustion is violent, which leads to the weakness of noise and vibration. In this paper, the combustion process of a common-rail diesel engine was studied by employing two kinds of pistons. One has several grooves with inclined plane on the piston crown to generate swirl during the compression and expansion strokes in the cylinder in order to improve the atomization of fuel. The other is a toroidal piston, generally used in high speed diesel engines. To take photographs of flame and flaming duration, a four-stroke diesel engine was remodeled into a two-stroke visible single cylinder engine and a high speed video camera was used.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.1
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• pp.226-229
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• 2004

We investigated the comparative effect with different frequency and duration time of electroacupuncture(EA) for suppression of pain. Inflammation was induced by an intraplantar injection of 1 % carrageenan into the right hind paw. Bilateral EA stimulation with 2 Hz, 15 Hz and 120 Hz were delivered at those acupoints corresponding to Zusanli and Sanyinjiao in man via the needles in carrageenan-injected rats. The paw and tail thermal hyperalgesia were measured in 30-minute intervals after carrageenan injection using hot plate and tail flick analgesia meter, respectively. The significant difference was found between the control and any of EA frequencies examined. Especially 2 Hz EA presented more effective inhibitory effects compared with other frequency of EA in tail flick latency. The hyperalgesia induced by carrageenan was strongly inhibited by 2 Hz EA from 5 min post and reached sufficient effects from 20 min post EA treatment. These results suggest that EA treatment might be a useful therapy for mitigation of inflammatory pain.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.16 no.4
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• pp.248-253
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• 2013

Purpose: The aim of this study was to compare the efficacy and safety of band ligation and injection sclerotherapy in the endoscopic treatment of children with variceal bleeding. Methods: The study population included 55 children, all of whom were treated at the time of endoscopic diagnosis of esophageal varices at Asan Medical Center, Seoul, Korea, between January 1994 and January 2011. The primary outcomes included initial success rates and duration of hemostasis after endoscopic management (band ligation vs. injectionsclerotherapy). Results: The mean age was $6.7{\pm}5.2$ years and the mean follow-up time was $5.4{\pm}3.7$ years. The most common cause of esophageal varices was biliary atresia. Of 55 children with acute variceal bleeding, 39 had band ligation and 16 had injection sclerotherapy. No differences between groups were observed in terms of the size, location, and presence of red color sign. The success rates of band ligation and sclerotherapy in the control of acute bleeding episodes were 89.7% and 87.5%. The mean duration of hemostasis after endoscopic intervention was $13.2{\pm}25.1$ months. After one year, 19 of 39 patients (48.7%) treated with band ligation and 7 of 16 patients (43.8%) with injection sclerotherapy had experienced rebleeding episodes. Complications after the procedures were observed in 10.3% and 18.8% of children treated with band ligation and injection sclerotherapy. Conclusion: The results of our current study suggest that band ligation and injection sclerotherapy are equally efficient treatments for the control of acute variceal bleeding and prevention of rebleeding.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.38-46
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• 2008

An object of this study is to understand the correlation between the characteristics of an engine performance and combustion characteristics, applying BD20 fuel reformed by ultrasonic energy irradiation to diesel engines. Before conducting the main experiment, an experiment was performed to determine the optimum injection timimg of reformed BD20 by ultrasonic energy irradiation. To control the duration of the ultrasonic energy irradiation, the capacity of an ultrasonic energy fuel supply system was tested with 550cc and 1100cc chambers. As the result of the analysis of the regular BD20 and reformed BD20 by ultrasonic energy irradiation, the BSFC and the Power of the reformed BD20 was improved 3% and 6%, respectively compared to those of non-irradiated BD20. When the fuel injection timing was delayed by $5^{\circ}$, the engine power was improved by 3%, and the BSFC was improved by 2%. The maximum cylinder pressure of reformed BD20 was improved by a maximum of 6% in comparison to that of regular BD20, and demonstrated a synergistic effect of 3% by delaying the injection timing $5^{\circ}$.

• Journal of Digital Contents Society
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• v.18 no.4
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• pp.699-706
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• 2017

This study aims to investigate the effects of a massage device with vibration and pressure functions and a manual massage on the degree and duration of pain among patients after intramuscular injection. This study used a quasi-experimental design with nonequivalent control group. The experimental group had lower pain scores (t= 7.40, p =.001) and shorter durations of pain (t= 5.25, p=.001) than the control group. The results showed that after intramuscular injection, a massage device with vibration and pressure functions effective to reduce the degree and duration of pain than a manual massage. Therefore, the application of a massage device with vibration and pressure functions after intramuscular injection will contribute to the promotion of patient safety and the reduction of nurse workload.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.457-464
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• 2006

Controlled auto ignition (CAI) combustion, also known as HCCI (homogeneous charge compression ignition), offers the potential to simultaneously improve fuel economy and reduce emission. CAI-combustion was achieved in a single cylinder gasoline DI engine, with a cylinder running in a CAI mode. Standard components were used the camshafts which had been modified in order to restrict the gas exchange process. The effects of air-fuel ratio, residual EGR rate and injection timing such as early injection and late injection on the attainable CAI combustion region were investigated. The effect that injection timings on factor such as start of combustion, combustion duration and heat release rate was also investigated. From results early injection caused the mixture to ignite earlier and burn more quickly due to the exothermic reaction during the recompression and gave rise to good mixing of the fuel-air.

• Journal of Dental Anesthesia and Pain Medicine
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• v.15 no.2
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• pp.63-68
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• 2015

Background: Conventional anesthetic nerve block injections into the mandibular foramen risk causing nerve damage. This study aimed to compare the efficacy and safety of the anterior technique (AT) of inferior alveolar nerve block using felypressin-propitocaine with a conventional nerve block technique (CT) using epinephrine and lidocaine for anesthesia via the mandibular foramen. Methods: Forty healthy university students with no recent dental work were recruited as subjects and assigned to two groups: right side CT or right side AT. Anesthesia was evaluated in terms of success rate, duration of action, and injection pain. These parameters were assessed at the first incisor, premolar, and molar, 60 min after injection. Chi-square and unpaired t-tests were used for statistical comparisons, with a P value of < 0.05 designating significance. Results: The two nerve block techniques generated comparable success rates for the right mandible, with rates of 65% (CT) and 60% (AT) at both the first molar and premolar, and rates of 60% (CT) and 50% (AT) at the lateral incisor. The duration of anesthesia using the CT was $233{\pm}37min$, which was approximately 40 min shorter than using the AT. This difference was statistically significant (P < 0.05). Injection pain using the AT was rated as milder compared with the CT. This difference was also statistically significant (P < 0.05). Conclusions: The AT is no less successful than the CT for inducing anesthesia, and has the added benefits of a significantly longer duration of action and significantly less pain.

• Journal of ILASS-Korea
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• v.10 no.1
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• pp.17-23
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• 2005

Even though a relatively complete knowledge base has been established for diesel sprays, much of the knowledge cannot be directly translated to correlate the characteristics of gasoline spray. The macroscopic characteristics of gasoline impingement spray was investigated with photographic and image processing technique by Particle Motion Analysis System. The injector with single hole nozzle diameter of 0.28 mm was used in this experiment and the injection duration was selected as 10 msec. The injection pressure with 0.3, 0.35, and 0.4 MPa, impingement distance or 70, 100 and 130m, impingement angle or 0.15, 30 and $45^{\circ}$ were employed for the variables to affect the spray characteristics of impinging spray. It is clear that there is the analogy on the spray tip penetration between the gasoline impinging jet and diesel free jet. The spray tip penetration of impinging gasoline spray is proportional to the quarter power of the time after start of injection. The maximum height of impinging gasoline spray is also proportional to the quarter power of the time regardless of impingement distance, impingement angle and injection pressure. In addition, the effect of impingement angle on the spray tip penetration is significant according to the time after start of injection, even though there is minor effect in the initial stage of time after start of injection. Moreover, there is no remarkable effect of injection pressure on the spray tip Penetration under the experimental condition used in this study.