• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.62-68
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• 2004

In this study, SHS process has been employed to fabricate porous $MoSi_2$ material with electric-resistive heating capability through the control of pore size. The preform for SHS reaction was consisted of molybdenum powder with different sizes and silicon powder with different contained quantity. The size of the $MoSi_2$ particles thus formed was determined by the generated heat of combustion, not by the size of molybdenum powder. However, the pore size of $MoSi_2$ composite was proportional to the particle size of molybdenum powder. that is the coarser the molybdenum powder used, the larget the formed pore size. Based on these results, the porous $MoSi_2$ composite could be fabricated with a desired pore size. By orienting the porous molybdenum disilicide-based material in the form of pore size gradient, porous materials used for filters with improved dirt-holding capacity can be manufactured.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05b
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• pp.102-105
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• 2005

가스센서는 응용 분야와 기능 및 종류가 다양하고 최첨단 분야로서 학문적으로는 물리, 화학, 전기, 전자 및 기계 등의 배경을 필요로 하며 산업적으로는 공업 전 분야와 농림, 축산, 사무기기에서 뿐만 아니라 공해 방진용(자동차 연소제어 및 배출가스 제어, 대기오염 감시등), 민생용(조리, 환기, 공조 등), 교통 보안용(음주운전측정 및 음주운전 방지장치 등), 방재용(가스 누설 탐지기, 불완전 연소 방지, 산소 결핍, 화재 등), 의료용(호기, 마취가스의 분석 등) 매우 광범위하며 점점 더 확대되어 가고 있다. 본 연구에서는 검출 가스 종류에 따라 졸-겔법으로 감응막을 최적 설계하고, 최적으로 설계된 감응막을 디핑법으로 코팅처리한 후 최적으로 열처리하여 센서를 제작하였다. 또한, 자체 제작한 가스검출 시스템에 제작된 센서를 장착하여 센서의 가스 검출 특성을 측정하고, 측정 데이터를 이용하여 휴대용 가스 검출 시스템을 설계 제작하였다.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.23-30
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• 2006

A thery was developed to design a high pressure vessel with combined structure of the metal and the composite to withstand the pressure of several tens of thousands psias to reduce the weight of the impulse motor which produces high level of thrust within several tens of seconds. The elastic-plastic stress analyses were carried out to prove the validity of the design theory. A combustion chamber of the impulse motor was designed by the design theory, fabricated, and tested by the hydraulic pressure and the static firings. The bursting pressures from the tests were compared to those predicted by the design theory and the stress analyses and found to be almost the same. It will be possible to design the high pressure vessel with combined structure of the metal and the composite very easily by the proposed design theory.

• Plant Journal
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• v.13 no.2
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• pp.34-38
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• 2017

To reduce global warming, there are so many studies, investments and efforts. The Post Combustion $CO_2$ Capture technology is one of these efforts. But the technologies are having trouble with reducing operating prices. And CCS technology which is using amine solvent uses high price amine solvent. There is solvent losses naturally when operating plant. The solvent loss makes operating and maintenance price higher. In this study, how the washing column of treated flue gas affects the losses of amine solvent and operating was studied.

• Fire Science and Engineering
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• v.32 no.3
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• pp.8-13
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• 2018

It was conceived from the realization that there was a lack of studies on the fire risk compared to utility and importance of plastic which is widely used. In this study, the fire hazard of five types of plastic products was measured by Cone Calorimeter (ISO 5660-1). As a result, the time to ignition (TTI) of polyvinyl Chloride (PVC) plate delayed TTI (196 s), and polystyrene (PS) plate had the shortest TTI of 19 s. The total heat release (THR) of PS plate was measured at 213.07 % higher than the lowest measured PVC plate. Also, the PS plate will have 1.45 to 4.21 times higher $CO_2$ than other plastics, resulting in the highest incomplete combustion and the greatest possible damage of life. Thus, assessing the risk of fire revealed that PS plate is the most dangerous and PVC is the safest.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.45-50
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• 2015

The goal of this research is the create novel magnets with no rare-earth contents, with larger energy product by comparison with currently used ferrites. For this purpose we developed nano-sized hard-type/soft-type composite ferrite in which high remanent magnetization (Mr) and high coercivity (Hc). Nano-sized Ba-ferrite, Ni-Zn ferrite and $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ composite ferrites were prepared by sol-gel combustion method by use of glicine-nitrate and citric acid. Nanocomposite ferrites were calcined at temperature range $700-900^{\circ}C$ for 1h. According to the X-ray diffraction patterns and FT-IR spectra, single phase of NiZn-ferrite and Ba-ferrite were detected and hard/soft nanocomposite ferrite was indicated to the coexistence of the magnetoplumbite-structural $BaFe_{12}O_{19}$ and spinel-structural $Ni_{0.5}Zn_{0.5}Fe_2O_4$ that agreed with the standard JCPDS 10-0325 data. The particle size of nanocomposite turn out to be less than 120 nm. The nanocomposite ferrite shows a single-phase magnetization behavior, implying that the hard magnetic phase and soft magnetic phase were well exchange-coupled. The specific saturation magnetization ($M_s$) of the nanocomposite ferrite is located between hard ($BaFe_{12}O_{19}$) and soft ferrite($Ni_{0.5}Zn_{0.5}Fe_2O_4$). The remanence (Mr) of nanocomposite ferrite is much higher than that of the individual $BaFe_{12}O_{19}$ and $Ni_{0.5}Zn_{0.5}Fe_2O_4$ ferrite, and $(BH)_{max}$ is increased slightly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.662-668
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• 2018

Most electric rooms are located in the underground spaces of buildings. When a fire occurs in electrical equipment, the fire expands to cable insulation material, resulting in toxic smoke and combustion products. If the smoke and combustion products quickly move vertically and horizontally, the evacuation of occupants and firefighting activities will be hindered. Therefore, it is necessary to design optimal equipment for smoke control in cases of fires in electric rooms. This study analyzes the characteristics of smoke and combustion products in fires in a cubicle-type switchboard in an electric room using PyroSim, which is based on the program Fire Dynamics Simulator (FDS). The fire modeling consists of four scenarios according to the operation mode of the mechanical ventilation equipment, the amount of air supply and exhaust, and the location of the air supply slot. The analysis shows that the mechanical ventilation equipment improves the smoke density, visibility, carbon monoxide concentration, and temperature characteristics. The visibility and temperature characteristics were improved when the air flow rate and the location of the air supply slot from fire defense regulations were applied.

• Fire Science and Engineering
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• v.15 no.1
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• pp.16-22
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• 2001

Thermal properties of PP and LLDPE dusts from chemical plant and their risks of coexisting with oxidizer were investigated by a pressure vessel. The thermal decomposition of PP and LLDPE dusts with temperature using DSC and the weight loss with temperature using TGA were also investigated to find the thermal hazard of PP and LLDPE dusts. Using the pressure vessel which can estimate ignition and explosion of PP and LLDPE dusts coexisting with oxidizer, a series of bursting of a rupture disc, experiments has been conducted by varying the orifice diameters the weight ratio of the sample coexisting with oxidizers and the species of oxidizer. And fire gases was measured by gas analyser ($ECOM-A^+$). According to the results of the thermal analysis of PP and LLDPE dusts, the decomposition temperature range of PP and LLDPE dusts was 200 to 350 and 300 to $500^{\circ}c$, respectively. The risk of PP and LLDPE dusts coexisting with oxidizer was increased as the orifice diameter was decreased. On the other hand, it was increased as the weight ratio of the sample to the oxidizer were increased. In addition, the risk of PP and LLDPE dusts coexisting with oxidizer was affected by the decomposition temperature of the sample and oxidizer. It is found that the risk of fire becomes high when the decomposition temperature of the sample is about same as that of oxidizer. Also, the fire gases was occurred carbon monoxide and carbon dioxide. The amount of carbon monoxide generated was found to be much higher in PP decomposition than in LLDPE due to incomplete combustion of PP which has high content of carbon in chemical compound.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.911-917
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• 2015

The objective of this work focuses on the analysis of injection rate and macroscopic spray behavior characteristics with injection pressures as well as combustion and exhaust emission characteristics with injection timing and injection pressure by using a common rail single-cylinder diesel engine. The injection rate was measured by applying the Bosch method, and macroscopic spray behavior characteristics were analyzed with a constant-volume vessel and a high-speed camera. In addition, combustion and emission characteristics were analyzed in a common-rail single-cylinder diesel engine with precise control of fuel injection timing and pressure. For injection pressures of 30MPa and 50MPa, the injection rate was higher at 50 MPa, and the spray development (penetration) was also higher in the same elapsed time. The peak in-cylinder pressure and rate of heat release showed a tendency to decline as injection timing was delayed, and the peak in-cylinder pressure and rate of heat release were slightly higher for higher injection pressures. Higher injection pressures also reduced the mean effective pressure, while the indicated mean effective pressure and torque increased as injection timing was delayed to TDC. Nitrogen oxides had a peak level at injection timings of $BTDC20^{\circ}$(30MPa) and $BTDC15^{\circ}$(50MPa); carbon monoxide emissions were reduced by delaying injection timing from $BTDC30^{\circ}$.

• Journal of Environmental Science International
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• v.6 no.3
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• pp.267-276
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• 1997

It has been studded that combustion and the production of air pollution of anthracite - bituminous coal blend In a fluidized bed coal combustor, The objects of thIns study were to investigate mixing characteristics of the particles as well as the combustibility of the low grade domestic anthracite coal and Imported h19h calorific bltununous coal in the fluidized bed coal combustor. They were used as coal samples ; the domestic low grade anthracite coal with heating value of 2,010kca1/kg and the Imported high grade bituminous coal with beating value of 6,520kca1/kg. Also, the effects of air flow rate and anthracite fraction on the reaching time of steady state condition have been studied. The experimental results are presented as follows. The time of reaching to steady state was affected by the temperature variation. The steady state time was about 120 minute at 300sc1h which was the fastest. It has been found that $O^2$ and $CO^2$ concentration were reached steady state at about 100 minute. It has been found that $O^2$ concentration decreased and $CO^2$ concentration increased as the height of fluidlzed bed Increased. It was found that splash zone was mainly located from 25cm to 35cm above distributor. Also, as anthracite traction Increased, the mass of elutrlatlon particles Increased, and $CO^2$ concentration decreased. As gk flow rate Increased,$O^2$ concentration decreased and $CO^2$ concentration increased. Regardless of anthracite fraction and flow rate, the uncombustible weight percentage according to average diameter of elutriation particles were approldmately high In the case of One Particles. As anthracite traction and k now rate Increased, elutriation ratio Increased. As anthracite fraction was increased, exit combustible content over feeding combustible content was Increased. Regardless of anthracite fraction, size distribution of Ued material from discharge was almost constant. Over bed temperature 85$0^{\circ}C$ and excess air 20% , the difference of combution efficiencies were little. It is estimate that the combustion condition In anthracite-bituminous coal blend combustion is suitable at the velocity 0.3m/s, bed temperature 85$0^{\circ}C$, the excess air 20%.