• Journal of Power System Engineering
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• v.14 no.3
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• pp.5-12
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• 2010

The purpose of this study is to analyze heterogeneous distribution of branch-like structure at downstream region of inner spray. The previous many studies about diesel spray structure have yet stayed in the analysis of 2-D structure, and there are very few of informations which are concerned with 3-D analysis of the structure. The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray, and also the combustion characteristics of the diesel engines. Therefore, in order to investigate 3-D structure of evaporative spray the laser beam of 2-D plane was used in this study. Liquid fuel was injected from a single-hole nozzle (l/d=5) into a constant-volume vessel under high pressure and temperature in order to visualize the spray phenomena. The incident laser beam was offset on the central axis. From the images analysis taken by offset of laser beam, we examine formation mechanism of heterogeneous distribution by vortex flow at the downstream of the diesel spray. As the experimental results, the branch-like structure formed heterogeneous distribution of the droplets consists of high concentration of vapor phase in the periphery of droplets and spray tip of branch-like structure. Also the 3-D spatial structure of the evaporative diesel spray can be verified by images obtained from 2-D measurement methods.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.70-76
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• 2013

For the safe handling of styrene, this study was investigated the explosion limits of styrene in the reference data. The flash points and AITs(auto-ignition temperatures) by ignition delay time were experimented. As a results, the lower and upper explosion limits of styrene recommended 0.9 Vol.% and 8.0 Vol.%, respectively. The lower flash points of styrene by using closed-cup tester were experimented $29^{\circ}C{\sim}31^{\circ}C$. The lower flash points of styrene by using open cup tester were experimented $32^{\circ}C{\sim}36^{\circ}C$. This study measured relationship between the AITs and the ignition delay times by using ASTM E659 tester for styrene. The experimental AIT of styrene was $460^{\circ}C$.

• Journal of the Korean Institute of Gas
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• v.13 no.4
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• pp.40-45
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• 2009

In order to investigate the compatibility of data in MSDS(Material Safety Data Sheet), the flash point of xylene isomer was measured by using Pensky-Martens closed cup (ASTM D93), Setaflash closed cup(ASTM D3278), Tag open cup(ASTM D1310), and Cleveland open cup (ASTM D92) testers. Also, the AITs(autoignition temperatures) of xylene isomers were measured by using ASTM E659-78 tester. The measured the flash points and the AITs were compared with literatures and MSDS in KOSHA(Korea Occupational Safety and Health Agency). The measured the flash points and the AITs were different from those in literatures and MSDS. As a result, this paper is shown that it is needed to investigate combustion characteristics of xylene isomer for the fire safety objectives.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.237-240
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• 2002

Micro catalytic reactors are alternative propulsion device that can be used on a nano satellite. When used with a monopropellant, $H_2O_2$, a micro catalytic reactor needs only one supply system as the monopropellant reacts spontaneously on contact with catalyst and releases heat without external ignition, while separate supply lines for fuel and oxidizer are needed for a bipropellant rocket engine. Additionally, $H_2O_2$ is in liquid phase at room temperature, eliminating the burden of storage for gaseous fuel and carburetion of liquid fuel. In order to design a micro catalytic reactor, an appropriate catalyst material must be selected. Considering the safety concern in handling the monopropellants and reaction performance of catalyst, we selected hydrogen peroxide at volume concentration of 70% and perovskite redox catalyst of lantanium cobaltate doped with strondium. Perovskite catalysts are known to have superior reactivity in reduction-oxidation chemical processes. In particular, lantanium cobaltate has better performance in chemical reactions involving oxygen atom exchange than other perovskite materials. In the present study, a process to prepare perovskite type catalyst, $La_{0.8}Sr_{0.2}CoO_3$, and measurement of its propellant decomposition performance in a test reactor are described.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.11-22
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• 1994

The pupose of this study is to measure droplet size and velocity simultaneously for a transient diesel fuel spray in a quiescent chamber at atmospheric temperature and pressure. Generally, diesel combustion phenomena is mainly governed by characteristics of injection system and fuel spray. Therefore we need to clarify these characteristics for developing more economical diesel systems. In this study, correlation between droplet size and velocity was measured at downstream distance from nozzle. Governing parameters are pump speed and fuel quantity for the detailed nature in this transient diesel fuel spray. It is observed effect to the droplet size and velocity distribution. Velocity(peak, mean, rms), number density and droplet size were investigated simulaneously using PDA in the spray. Various results are presented to illustrate the effects of operation factors and correlation between the droplet diameter and velocity.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.4
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• pp.519-526
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• 2012

Recently fuel cell is considered to be a new technology that can substitute the ICE(Internal Combustion Engine) as well as overcome environmental issues. In military applications, fuel cell has an unique advantages, which are quietness, namely, stealth. The environmental requirement such as shock and vibration in military application, however, is very severe comparing to civilian demand. Especially, the safety concerning hydrogen storage is the most important problem. Among the candidate methods to store hydrogen, the metal hydride storage is promising method owing to the storage mechanism of chemical absorption of hydrogen to metal hydrides. In this study, the new composition of Ti-Zr type metal hydride(A composition) was suggested and investigated to increase the hydrogen storage capacity. For comparison, the hydrogen charge-discharge properties were investigated with the commercialized Ti-Zr type metal hydride(B composition) using PCT(Pressure-Composition-Temperature) measurement. Also two hydrogen storage cylinders were loaded with each metal hydride and their hydrogen charging and discharging characteristics were investigated. As a result, it was found that the new Ti-Zr type metal hydride has a slightly higher hydrogen storage capacity compared to commercial Ti-Zr type metal hydride.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.5
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• pp.563-569
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• 2012

The superheater and reheater tubes of a heavy-load fossil power plant boiler can be damaged by overheating, and therefore, the degree of overheating is assessed by measuring the oxide scale thickness inside the tube during outages. The tube temperature prediction from the oxide scale thickness measurement is necessarily accompanied by destructive tube sampling, and the result of tube temperature prediction cannot be expected to be accurate unless the selection of the overheated point is precise and the initial-operation tube temperature has been obtained. In contrast, if the tube temperature is to be predicted analytically, considerable effort (to carry out the analysis of combustion, radiation, convection heat transfer, and turbulence fluid dynamics of the gas outside the tube) is required. In addition, in the case of analytical tube temperature prediction, load changes, variations in the fuel composition, and operation mode changes are hardly considered, thus impeding the continuous monitoring of the tube temperature. This paper proposes a method for the short-term prediction of tube temperature; the method involves the use of boiler operation information and flow-network-analysis-based tube heat flux. This method can help in high-temperaturedamage monitoring when it is integrated with a practical tube-damage-assessment method such as the Larson-Miller Parameter.

• 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 Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.127-133
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• 2020

The international cancer research institute under the WHO designated fine dust as a first-class carcinogen. Particular matter refers to dust that is small enough to be invisible and floating in the air. Particular matter is mainly emitted from the combustion process of fossil fuels such as coal and oil, and is a risk factor that can cause lung disease, pneumonia, and heart disease. The Ministry of Environment recently analyzed the output data of 10 fine dust measuring stations and, as a result, announced that about 60% had an error that the existing atmospheric measurement concentration was higher. In order to accurately predict fine dust, the wind direction and measurement position must be corrected. In this paper, in order to solve these problems, fuzzy rules are used to solve these problems. In addition, in order to calculate the fine particulate sensation index actually felt by pedestrians on the street, a computer simulation experiment was conducted to calculate the fine particulate sensation index in consideration of weather conditions, temperature conditions, humidity conditions, and wind conditions.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.5
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• pp.542-547
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• 2015

Since the oil price has been significantly jumped for several years, a heavy oil of low quality has been mainly used in the diesel engine of the merchant ship. Thus, a combustion chamber of the engine has been often exposed to severely corrosive environment more and more because temperature of the exhaust gas of the combustion chamber has been getting higher and higher with increasing of using the heavy oil of low quality. As a result, wear and corrosion of the engine parts such as exhaust valve, piston crown and cylinder head surrounded with combustion chamber are more serious compared to the other parts of the engine. Therefore, an optimum repair welding for these engine parts is very important to prolong their lifetime in a economical point of view. In this study, Inconel 625 filler metal were welded with GTAW method in the cast steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected and base metal zones were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% $H_2SO_4$ solution. The weld metal and base metal zones exhibited the highest and lowest values of hardness respectively. Furthermore, the corrosion current density of the weld metal zone revealed the lowest value, having the highest value of hardness. The corrosive products with red color and local corrosion like as a pitting corrosion were considerably observed at the base metal zone, while these morphologies were not wholly observed in the weld metal zone. In particular, the polarization characteristics such as impedance, polarization curve and cyclic voltammogran associated with corrosion resistance property were well in good agreement with each other. Consequently, it is suggested that the mechanical and corrosion characteristics of the piston crown can be predominantly improved by repair welding method using the Inconel 625 electrode.