• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.2
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• pp.46-54
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• 2015

Nitrous oxide is known as green and safe propellant, and can be supplied by its own vapor pressure. So, many liquid propulsion research institutes and university laboratories use nitrous oxide as oxidizer of experimental liquid rocket engine. However, the unknown explosions occurred twice during hot fire experiments using subscale ethanol/nitrous oxide thruster. In this paper, we surmised that the explosions were caused by the decomposition of nitrous oxide in the injector body and the recondensation of nitrous oxide. Improvement and the safe handling methods are suggested.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.107-113
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• 2005

A calorimeter of 2-ton thrust level rocket engine chamber has been developed to measure the wall heat flux. The liner of the chamber is made of copper-chromium alloy to maximize the heat transfer performance and structural strength. 1-D design code based on empirical correlations has been used for the prediction of the global thermal characteristics while 3-D CFD has been applied for the verification of local cooling performance. The predicted average wall heat flux at the throat is 43 $MW/m^{2}$ for the combustion chamber pressure of 53 bar. The chamber structure is confirmed to be safe at the pressure of 150 bar through 2-D stress analysis and measurement of the strain of the test species. Finally, the test of pressurizing the calorimeter chamber has been performed with water at the pressure of 150 bar in room temperature environment. No thermal damage has been detected after the hot-fire test in the test nozzle of same cooling performance with the developed calorimeter though the measured throat heat flux is higher than the design value by 10%.

• The Korean Journal of Air & Space Law and Policy
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• v.33 no.1
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• pp.205-226
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• 2018

For sustainable development of air transport, the establishment and application of international standards of environmental protection area is significant. The development and use of alternative fire extinguishing agent to Halon, which is used for the fire extinguishing systems of engine nacelles/APU and cargo compartments, has been requested in order to protect the ozone layer. The ICAO has been active in preparing international standards and recommended practices (SARPs); however, certification of alternative fire extinguishing agents has been postponed due to technical readiness problem.. Consequently, the implementation of SARPs has also been postponed by two years from the end of 2016. to the end of 2018. As such consequences have caused confusion among Member States regarding its implementation, it is necessary to discuss and pay more attention to this issue. ICAO Council and Air Navigation Commission should consider between setting the implementation time frame earlier or giving enough time for mature readiness and preparedness. Also in order to minimize the unnecessary discharge of Halon owned by Member States, it is necessary to consider efficient management methodologies; for example, requesting fire extinguisher manufacturers to recharge in professional ways. For the successful implementation of the SARPs, ICAO developed an implementation task list as including notification of differences, establishment of a national implementation plan, drafting of the modification to the national regulations and means of compliance, adoption of the national regulations and means of compliance. Member States can develop their own rule making process in reference with the ICAO implementation task list. This issue was presented and discussed during the 54th Conference of Directors General of civil aviation, Asia and Pacific Regions which was held in Ulaanbaatar, Mongolia in 2017 with significant attention among participated Contacting States. In this regards, ICAO Council and Air Navigation Commission should consult with Legal Bureau lawyers regarding SARPs preparing process to eliminate difficulties and confusions for proper implementation within effective date.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.1
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• pp.30-35
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• 2000

The experimental study on the lift-off height of diffusion flames was conducted to investigate the damage of swirl-coaxial injector used in $GO_2$/kerosene rocket engine during initial stage of ignition. To investigate the causes of damage and to prevent further damage of the injector, experimental injector was designed and hot fire tests were performed with varying propellant momentum ratio($\frac{Momentum of {GO_2}}{Momentum of Kerosene}$) from 1 to 12. In experimental coaxial injector, kerosene is sprayed from the central nozzle with swirl and $GO_2$ sprayed around the kerosene nozzle in the direction parallel to the axis of combustion chamber. Chamber pressure are close to the atmospheric condition. Lift-off height was measured by still images from camcoder and average values were used as data.

• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.111-117
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• 2011

This paper suggests the passenger model considered evacuation behavioral characteristics on the passenger ship fire using a rules-based agent technique. The existing evacuation simulation system was modeled only passenger speed. The speed-based model considered passenger's physical characteristics, so it couldn't consider evacuation behavioral characteristics. For solving this problem, we modeled the passenger model using a rule-based agent applied evacuation behavioral characteristics. The rule-based agent consists of knowledge base and inference engine. In knowledge base, we represented evacuation behavioral characteristics, and chose the examples of the evacuation behavioral characteristics to show various patterns of behavior. And we simulated in the IMO MSC/Circ.1238 example 8 and we proved the simulation results could represent variety patterns of human behavior.

• The Journal of the Society of Stroke on Korean Medicine
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• v.11 no.1
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• pp.61-69
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• 2010

Objective : To investigate the syndrome differentiation's types and herbal medicine of migraine through Chinese journals review Methods : Journal search was performed using the searching engine of China Academic Journal(CAJ) in China National Knowledge Infrastructure(CNKI) from January 2000 to November 2010. Searching key words were "migraine", "chinese traditional medicine" and "syndrome differentiation". We included all kinds type of journals that explained or referred definite syndrome differentiations. The methods of treatment and Herbal medications by syndrome differentiation in contents of finally selected journals were extracted and summarized. Results : Eighteen chinese journals were selected finally. Fifteen kinds of syndrome differentiations about migraine were investigated, which included blood stasis due to qi stagnation (氣滯血瘀) quoted 15 times, middle obstruction of phlegm-dampness (痰濕中阻) 11 times, liver yang transforming into wind (肝陽化風) 10 times, deficiency of qi and blood (氣血虧虛) 6 times, wind-cold invading 風寒侵襲 淸陽鬱遏 4 times, cold invading reverting yin (寒犯厥阴) 4 times, liver-kidney deficiency (肝腎虧虛) 3 times, liver qi depression and qi stagnation (肝鬱氣滯) 2 times, liver depression transforming into fires (肝鬱化火) 2 times, wind-fire of liver-gallbladder (肝膽風火) 3 times, intense stomach fire and heat (胃火熱盛) 2 times, insufficiency of blood deficiency (血虛不榮) 2 times, insufficiency of qi deficiency (氣虛不充) 2 times, insufficiency of kidney qi and sea of marrow deficiency (腎氣不足, 髓海空虛) 2 times, and qi depression due to wind invading (風邪侵襲, 氣鬱不宣) 2 times. Conclusion : We suggests the first choice of oriental treatment for migraine can be considered among syndrome differentiation's types of blood stasis due to qi stagnation, middle obstruction of phlegm-dampness, liver yang transforming into wind, deficiency of qi and blood, and cold invading reverting yin. further systematic study will be needed.

• Journal of the Korean Institute of Gas
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• v.25 no.2
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• pp.22-27
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• 2021

This paper is a purpose to study the failure examples for LPG vehicle. The first example, the researcher certified the incongruity phenomenon decreased engine power by ignition fire leakage because of spark plug threaded part damage assembling in cylinder head. The second example, the timing mark that accurately adjusting the camshaft and crankshaft position were twisted about 0.5 block each other. Finally, the researcher seeked the disharmony phenomenon as it couldn't set ignition timing. The third example, the researcher knew the failure phenomenon by interrupted the closing period for intake valve moving with air flow in the number 3 port of cylinder head as the foreign substance in cylinder head didn't remove. Therefore, the manager of a car has to thorough going inspect and the manufacture of a car must remove the cause of failure with quality assurance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.4
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• pp.76-81
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• 2003

To investigate the convective heat transfer phenomena inside the Lox/Kerosene liquid rocket combustion chamber, hot fire tests were performed by using a water-cooled calorimetric chamber. The calorimetric chamber consists of one cylindrical section and nozzle section with independent cooling passage. To measure the heat flux, thermocouples were installed inlet and outlet of cooling passage of each section. The investigated range of combustion chamber pressure is from 100 psi to 300psi at fixed O/F ratio of 2.0 and radiation heat transfer from the hot gas to the surface is not considered. The measured heat flux was almost linearly depended on the chamber pressure.

• Journal of Astronomy and Space Sciences
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• v.28 no.3
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• pp.233-239
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• 2011

A series of computational analyses was performed to predict the cooling process by the cooling channel of preburners used for kerosene-liquid oxygen staged combustion cycle rocket engines. As an oxygen-rich combustion occurs in the kerosene fueled preburner, it is of great importance to control the wall temperature so that it does not exceed the critical temperature. However, since the heat transfer is proportional to the speed of fluid running inside the channel, the high heat transfer leads to a trade-off of pressure loss. For this reason, it is necessary to establish a certain criteria between the pressure loss and the heat transfer or the wall surface temperature. The design factors of the cooling channel were determined by the computational research, and a test model was manufactured. The test model was used for the hot fire tests to prove the function of the cooling mechanism, among other purposes.

• The Korean Journal of Health Service Management
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• v.7 no.3
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• pp.29-44
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• 2013

The purpose of this study is to give the users, who wants to know the information about CPR and AED on the Internet, more accurate information which is analyzed and considered with the factors to improve the contents of them. The source of the instrument for this study is from the contents of twenty four websites which is able to join in and searched by the Web Search Engine with four keywords: 'Cardiopulmonary Resuscitation', 'CPR', 'Automated External Defibrillator', and 'AED'. According to the results of the study, frequency questions of more than 50% among 53 questions on whether to suggest were investigated as 22 questions from content analysis results of the websites, and it showed that the highest frequency, which were examined to that chest compressions and respiratory rate; 79.2%. The correctness of the contents of the all websites of the study is as low as 36.00 point full marks at 100 points.