• Journal of Energy Engineering
• /
• v.10 no.3
• /
• pp.206-213
• /
• 2001

Gasification kinetics of an Indonesian sub-bituminous coal-char with $CO_2$at elevated pressure was investigated with a pressurised drop tube furnace reactor. The effects of reaction temperature (900~140$0^{\circ}C$), partial pressure of carbon dioxide (0.1~0.5 MPa), and total system pressure (0.5, 0.7, 1.0, 1.5MPa) on gasification rate of the coal char with $CO_2$have been determined. It was found that the gasification rate was dependent on the total system pressure with the same partial pressure and temperature. The $n^{th}$ order rate equation (R=k $P^{g}$ $_{asn}$) was modified to be R=k $P^{g}$ $_{asn}$ $P^{m}$ $_{total}$ to describe the gasification rate where the total system pressure was changed. The gasification reaction rate of char-$CO_2$at high temperature and elevated pressure may be expressed as dX/dt=(174.1)exp(-71.5/RT)( $P_{CO2}$)0.40( $P_{total}$ )0.65(1-X)$^{2}$ 3/.X> 3/.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.7
• /
• pp.569-576
• /
• 2014

Sensor node means a device to include sensor, amplifier, and data acquisition (DAQ) equipment. The sensor converts physical signals to electric signals and weak signals from the sensor can be amplified through the amplifier. DAQ equipment converts analog signal to digital signal and collects converted digital signal. Since the sensor node is sensitive to the environment so that selection of mounting position and fixture design of sensor are applied differently depending on the characteristics of a target. This study is about designing and manufacturing sensor node to be used in a machine tool. The environment of machine tool is very severe due to noise, temperature fluctuation, and dust, etc. Hence, the sensor and amplifier must be designed and manufactured by considering the environmental issues. The designed and manufactured sensor node was tested for the reliability and effectiveness of the developed sensor nodes in the study.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.1
• /
• pp.89-94
• /
• 2011

The EGR system is one of important components in diesel engine. The regulation on NOx emission has been tightened up. Therefore, it is a significant issue to develop and commercialize the high efficient EGR cooler system that reduces NOx emission in DI diesel engine. Key performance factor of the EGR cooler system is how to properly design both wavy cooling fins and gas tubes. This paper proposes a high efficient EGR cooler that has been upgraded with both the optimized wavy cooling fins and the improved shape of structure. The evaluation of the heat exchange efficiency, outlet temperature, and gas pressure drop of the EGR cooler is performed with the prototype of the proposed EGR cooler. The result shows a good solution and will be implemented to the model of a clean diesel engine being developed for both domestic and overseas market.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.19 no.6
• /
• pp.81-90
• /
• 2015

In order to know the characteristics of the hypersonic air-breahting engine, high altitude and Mach number ground test is necessary. Therefore, high pressure and high temperature condition should be simulated to do ground test of the hypersonic air-breathing engine. In this paper, the hypersonic air-breathing engine ground test facility of the Korea Aerospace Research Institute was introduced and the composition and characteristics were described.

• The KSFM Journal of Fluid Machinery
• /
• v.19 no.3
• /
• pp.19-24
• /
• 2016

Oil sands are a mixture of sand, clay, and a high-viscosity petroleum called bitumen. Steam-Assisted Gravity Drainage (SAGD) is the most viable and environmentally safe recovery technology for extracting bitumen. It extracts the viscosity-lowered bitumen by high pressure, high temperature steam injected into the bitumen reservoir. The steam is produced at the Central Processing Facility (CPF). Typically, more than 90% of the energy consumed in producing bitumen are used to generate the steam. Fuels are employed in the process, which cause economic and environmental problems. This paper explores the retrofit of heat exchanger network to reduce the usage of hot and cold utilities. The hot and cold utilities are reduced respectively 6% and 37.3% which in turn resulted in 5.3% saving of total annual cost by improving the existing heat exchanger network of the CPF.

• Journal of Hydrogen and New Energy
• /
• v.21 no.4
• /
• pp.264-270
• /
• 2010

Recently, the most promising methods for high purity hydrogen production are membranes separation such as polymer, metal, ceramic and composites. It is well known that Pd and Pd-alloys membranes have excellent properties for hydrogen separation. However, it has hydrogen embrittlement and high cost for practical applications. Therefore, most scientists have studied new materials instead of Pd and Pd-alloys. On the other hand, TiN powders are great in resistance to acids and chemically stable under high operating temperature. In order to get specimens for hydrogen permeation, the TiN powders synthesized were consolidated together with Co, Ni powders by hot press sintering (HPS). During the consolidation of powders at HPS, heating rate was 10 K/min and the pressure was 10 MPa. It was characterized by XRD, SEM. Also, we estimated the hydrogen permeability by Sievert's type hydrogen permeation membrane equipment.

• Journal of computational fluids engineering
• /
• v.7 no.3
• /
• pp.9-16
• /
• 2002

Most of modem aerospace gas turbines must be operated at a gas temperature which is several hundreds of degrees higher than the melting temperatures of the materials used in their construction. Complicated cooling schemes need to be employed in the combustor walls and in the high pressure turbine stages. Internal passages are cast or machined into the hot sections of aero-gas turbine engines and air from the compressor is used for cooling. In many cases, the cooling system is engineered to utilize jets of high velocity air, which impinge on the internal surfaces of the components. They are categorized as 'Impinging Cooling Method' and 'Vortex Cooling Method'. Specially, research of new cooling system(Vortex Cooling Method) that overcomes inefficiency of film cooling and limitation of space. The focus of new cooling system that improves greatly cooling efficiency using less amount of cooling air on surface heat transfer elevation. Therefore, in this study, a numerical analysis has been peformed for characteristics of flow and heat transfer in the swirl chamber and compared with the flow measurements by LDV. Especially, for understanding high heat transfer efficiency in the vicinity of wall, we considered flow structure, vortex mechanism and heat transfer characteristics with variation of the Reynolds number.

• Proceedings of the KIEE Conference
• /
• 1991.07a
• /
• pp.300-303
• /
• 1991

Sulphur-hexafluoride has extensively been used as an insulating gas of electric power equipment in substation for its high dielectric strength, non-toixity and non-flammable properties. But it is very expensive and is liquidizable under the condition of low temperature and high pressure. And it is very sensible to the locally high electric field strength. To resolve these problems, we studied 50% FOV and V-t characteristics of $SF_6-N_2$ mixtures under positive and negative lightning impulses using a 25mm rod-plane gap. 50% FOV of $SF_6-N_2$ 50% mixture was about 85% of pure $SF_6$ and it was known that $SF_6-N_2$ mixtures can be used as an economic substitution insulating gas for $SF_6$.

• The Journal of Engineering Geology
• /
• v.20 no.3
• /
• pp.271-279
• /
• 2010

Time-dependent behavior similar to secondary deformation related to mineral dissolution is easily observed when performing a laboratory pressure experiment. In this research, to observe the dissolution of quartz found in bentonite used as buffer material for the geological disposal of high-level waste (HLW) under conditions of high pH, we calculated the diffusion of $OH^-$ ions and the behavior of quartz dissolution using the homogenization analysis method. The results reveal that the rate of quartz dissolution is proportional to the temperature and interlayer water thickness. In particular, in a high-pH environment, the reacted area (and therefore the dissolution rate) increases with decreasing interlayer water thickness.

• Journal of the Korean Applied Science and Technology
• /
• v.15 no.4
• /
• pp.45-56
• /
• 1998

Methyl fructoside oleic acid polyester(MFPE), fructose-based sugar polyester, was synthesized by solvent-free, soap-free transesterification of methyl oleate with methyl fructoside(MF) as a sugar starting material in the presence of conventional potassium carbonate basic catalyst. Methyl fructoside was found to be an effective sugar starting material, because of its low softning point, high heat stability, high miscibility, and high reactivity than other sugars. Yield 98% of purified MFPE based on initial weight of MF was obtained at 1:5 of the molar ratio of methyl fructoside to methyl oleate, 2%(w/w) of potassium carbonate catalyst content, 20${\sim}$200mmHg of reduced pressure and $180^{\circ}C$ of reaction temperature. MFPE structure was confirmed by infrared and proton nuclear magnetic resonance spectroscopy. Physical properties of methyl of fructoside oleic acid polyester such as viscosity, HLB, solubility, color, refractive index, specific gravity, and density were similar to physical properties of sucrose polyesters(SPE) and vegetable oils. Then, it was elucidated that MFPE was sufficient to replace the SPE and conventional oils.