• Journal of Mechanical Science and Technology
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• v.18 no.11
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• pp.2058-2065
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• 2004

A light collecting probe named Multi-color Integrated Cassegrain Receiving Optics (MICRO) is applied to spark-ignited spherical spray flames to obtain the flame propagation speed in freely falling droplet suspension produced by an ultrasonic atomizer. Two MICRO probes are used to monitor time-series signals of OH chemiluminescence from two different locations in the flame. By detecting the arrival time difference of the propagating flame front, the flame propagation speed is calculated with a two-point delay-time method. In addition, time-series images of OH chemiluminescence are simultaneously obtained by a high-speed digital CCD camera to ensure the validity of the two-point delay-time method by the MICRO system. Furthermore, the relationship between the spray properties measured by phase Doppler anemometer (PDA) and the flame propagation speed are discussed with three different experimental conditions by changing the fuel injection rate. It was confirmed that the two-point delay-time method with two MICRO probes is useful and convenient to obtain the flame propagation speed and that the flame propagation speed depends on the spray properties.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.305-308
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• 2009

This paper presents the design and analysis of RF Front End for Wireless Heartbeat measurement System. In this work LNA, an inductor connected at the gate of the cascode transistor and capacitive cross-coupling are strategically combined to reduce the noise and the nonlinearity influences of the cascode transistors in a differential LNA. The Mixer is implemented by using the Gilbert-type configuration, cross pmos injection technique and the resonating technique for the tail capacitance. The resulting LNA achieves 1.26 dB NF, better than 1.88dB NF Typical Also Mixer resulting achieves 9.8dB at 100KHz.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.92-96
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• 1997

Recently, the life cycle of products is rapidly shortened and then the disposal of the used mold applied in development of the product is a difficult thing. In this study, we proposed the feasibility of new 3plate type mold base for recycling by analyzing of the existing standard mold base. And in order to apply new 3plate mold base in mold design and making, we constructed the specifications for parts such as runner stripper plate, cavity plate, core plate and slide core unit. Also, we confirmed the possibility of recycling mold base by testing a used 3plate mold for a Audio front pannel.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.20-25
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• 2004

In order to obtain the flame Propagation speed in freely falling droplet suspension Produced by an ultrasonic atomizer, a light collecting probe named Multi-color Integrated Cassegrain Receiving Optics (MICRO) is applied to spark-ignited spherical spray flames. Two MICRO probes are used to monitor time-series signals of OH chemilumine-scence from two different locations in the flame. The flame propagation speed is calculated by detecting the arrival time difference of the propagating flame front. In addition, time-series images of OH chemiluminescence are simultaneously obtained by a high-speed digital CCD camera to ensure the validity of the MICRO system. Furthermore, relationship between the spray properties measured by phase Doppler anemometer (PDA) and the flame propagation speed are discussed with k different experimental conditions by changing the fuel injection rate. It was confirmed that the MICRO probe system was very useful and convenient to obtain the flame propagation speed and that the flame propagation speed was different depending on the spray properties.

• Journal of the korean Society of Automotive Engineers
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• v.12 no.1
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• pp.33-39
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• 1990

This study has been conducted by experiments for distribution of concentration of helium gas, which is jetted into stationary atmosphere at the normal temperature and pressure. It is able to obtain the data for concentration of helium and air mixtures by the use of hot wire probe which has fast response. At an up stream, the concentration gradient which is attained is steep. At a down stream, the mixing time of helium and air is gradually shortened with the lapse of time in front of a jet. The arrival frequency of a jet in an unsteady area is mostly constant from 0% to 100% up to 80mm, but the time which is reaching to 100% is gradually to lengthen as a descending downstream. After starting a jet and the point of 90%, the mixing time is especially to lengthen. This reason comes from the turbulent intensity which causes for mixing of helium and air. This time difference which causes according to lengthen a jet should be considered in the design of combustion chamber.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.228-235
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• 2004

In this thesis, it is designed efficient electrode formation on the organic luminescent device. ITO electrode is treated with $O_2$plasma. In order to inject hole efficiently, there is proposed the shape of anode that inserted plasma polymerized films as buffer layer between anode and organic layer using thiophene monomer. It is realized efficiently electron injection to aluminum due to introduce the quantum well in cathode. In the case of device inserted the buffer layer by using the plasma poiymerization after $O_2$plasma processing for ITO transparent electrode, since it forms the stable interface and reduce the moving speed of hole, the recombination of hole and electronic ate made in the omitting layer. Compared with the devices without buffer layer, the turn-on voltage was lowered by 1.0(V) doc to the introduction of buffer layer Since the quantum well structure is formed in front of cathode to optimize the tunneling effect, there is improved the power efficiency more than two times.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.8
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• pp.1371-1376
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• 2008

A Steer-by-Wire system has so many advantages comparing with conventional mechanical steering system that it is expected to take key role in future environment friendly vehicle and intelligent transportation system. The mechanical connection between the hand wheel and the front axle will become obsolete. SBW system provides many benefits in terms of functionality, and at the same time present significant challenges - fault tolerant, fail safety - too. In this paper, failure analysis of SBW system will be performed and than sensor fusion technique will be proposed for fail safety of SBW system. A sensor fusion logic of steering angle sensor by using steering angle sensor, torque sensor and rack position sensor will be developed and simulated by fault injection simulation.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.630-638
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• 2009

A computational fluid dynamics(CFD) model is developed and validated with on-site experiments for a urea-based SNCR(selective non-catalytic reduction) process to reduce the nitrogen oxides($NO_x$) in a municipal incinerator. The three-dimensional turbulent reacting flow CFD model having a seven global reaction mechanism under the condition of low CO concentration and 12% excess air and droplet evaporation is used for fluid dynamics simulation of the SNCR process installed in the incinerator. In this SNCR process, urea solution and atomizing air were injected into the secondary combustor, using one front nozzle and two side nozzles. The exit temperature($980^{\circ}C$) of simulation has the same value as in situ experiment one. The $NO_x$ reduction efficiencies of 57% and 59% are obtained from the experiment and CFD simulation, respectively at NSR=1.8(normalized stoichiometric ratio) for the equal flow rate ratio from the three nozzles. It is observed in the CFD simulations with varying the flowrate ratio of the three nozzles that the injection of a two times larger front nozzle flowrate than the side nozzle flowrate produces 8% higher $NO_x$ reduction efficiency than the injection of the equal ratio flowrate in each nozzle.

• Journal of the Korean Society of Combustion
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• v.17 no.1
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• pp.37-47
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• 2012

Experimental study on comparison of diffusive-thermal self-excitation with buoyancy-driven one due to accumulation of partially premixed, preheated mixture in front of edge flame was conducted in horizontally and vertically injected laminar free-jet flames with an applied DC electric field of -10 kV. The application of horizontal injection method with the DC electric field to jet flames was experimentally designed to suppress heat-loss-induced self-excitation and thereby to highlight the definite difference between both diffusive-thermal and buoyancy-driven self-excitations with the same order of O(1.0 Hz), in that diffusive-thermal self-excitation has not been so far found experimentally in laminar jet flames. Flame stability maps in vertically and horizontally injected jet flames are presented. The distinct modes of individual self-excitation are shown to be well described by their own phase diagrams. The results show that buoyancy-driven self-excitation due to the accumulation of partially premixed, preheated mixtures in front of edge flame is branched from the buoyancy-induced self-excitation with O(10 Hz) due to a flame flicker. Once the buoyancy-driven self-excitation appears, it suppresses buoyancy-induced as well as diffusive-thermal self-excitation. The key characteristics for individual self-excitation are discussed and their functional dependencies of Strouhal number upon related physical parameters are also presented.

• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.54-61
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• 2005

An aquifer thermal energy storage (ATES) system can be very cost-effective and renewable energy sources, depending on site-specific parameters and load characteristics. In order to develop the ATES system which has certain hydrogeological characteristics, understanding the thermohydraulic process of an aquifer is necessary for a proper design of an aquifer heat storage system under given conditions. The thermohydraulic transfer for heat storage was simulated according to two sets of simple pumping and waste water reinjection scenarios of groundwater heat pump system operation in a two-layered aquifer model. In the first set of the scenarios, the movement of the thermal front and groundwater level was simulated by changing the locations of injection and pumping wells in a seasonal cycle. However, in the second set the simulation was performed in the state of fixing the locations of pumping and injection wells. After 365 days simulation period, the shape of temperature distribution was highly dependent on the injected water temperature and the distance from the injection well. A small temperature change appeared on the surface compared to other simulated temperature distributions of 30 and 50 m depths. The porosity and groundwater flow characteristics of each layer sensitively affected the heat transfer. The groundwater levels and temperature changes in injection and pumping wells were monitored and the thermal interference between the wells was analyzed to test the effectiveness of the heat pump operation method applied.