• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.4
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• pp.238-243
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• 2006

This paper presents novel ignition method for automotive 35W metal halide discharge lamp electronic ballast. At this study, the novel method of ignition is developed to reduce costs and size of the ballast. By use of the novel method, the voltage needed in ignition is decreased, which result in use of the lower voltage rating power devices compared with conventional method and product compactness was achieved by deleting a circuit generating negative voltage needed in ignition at an conventional circuit. In terms of luminosity, color rendering, light efficiency(lm/W) and lifespan, the metal halide lamp is superior to, but unlike halogen lamp, it have more complicated transient characteristics to reach its steady state than the conventional halogen lamp. Therefore, in this paper, the electronic ballast was designed such that the metal halide lamp could be optimized for the automotive, by applying a method of microcontroller-based digital control. The results of the proposed system is verified through various experiment results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.5
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• pp.491-496
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• 2008

New concept ramjet propulsion system with liquid bipropellant rocket using "Green Propellant" hydrogen peroxide for launch stage is proposed. In this novel concept, hydrogen peroxide gas generator produces hot oxygen at launch stage and kerosene injects to this jet in combustor. For basic study of this new concept ramjet system, investigation of auto-ignition characteristics and combustion of decomposed hydrogen peroxide and kerosene was conducted. In various test cases, auto-ignition and stable combustion was verified. The combustion temperature of 400°C and Fuel/Oxidizer mixture ratio of 0.6 were the limit of auto ignition. Through the experiment results, the possibility of novel concept combined propulsion system using hydrogen peroxide gas generator is ascertained.

• Advances in aircraft and spacecraft science
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• v.2 no.4
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• pp.445-467
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• 2015

The paper presents some details of the CFD modeling of a novel design where jet ignition devices replace the traditional spark plugs for a faster and more complete combustion. The numerical simulations show how the pre-chamber jet ignition in a Wankel engine differs from reciprocating piston engine applications. The jets issuing from the jet ignition pre-chamber have many different speeds in the different directions as the pressure build-up at the trailing edge of the rotating chamber makes extremely fast the ignition of the chamber mixture in the direction of rotation. Conversely it prevents the jet ignition in the opposite direction. Careful positioning along the periphery and design of the connecting pipes and the prechamber volume with the help of CFD simulations permits to achieve extremely fast and complete combustion as impossible with spark plugs. The paper proposes results of CFD simulations of the combustion evolution within a jet ignited Wankel engine rotor, detailing challenges and opportunities of the application, as well as a first assessment of the impact the faster and more complete combustion permitted by jet ignition may have on the performances of Wankel engines for unmanned aerial vehicles applications.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.215-218
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• 2015

Simultaneous laser ignition and spectroscopy is a scheme that enables rapid determination of the local equivalence ratio and condensed fuel concentration during a reaction in a two phase spray flame. We have conducted quantitative analysis of the LIBS signals according to the equivalence ratio, droplet size, droplet number density and droplet concentration as a part of novel feedback control strategy proposed for flame ignition and stabilization with simultaneous in situ combustion flow diagnostics. This is a desirable scheme since such real time information onboard an engine for instance can be constantly monitored and fed back to the control loop to enhance the mixing process and minimize emissions of unwanted species and potential combustion instability.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.229-230
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• 2013

The conventional Three-Stage electronic ballast is stable, but Two-Stage electronic ballast has been researching because of efficiency. Three-Stage electronic ballast is consisted of PFC circuit, buck converter, and inverter circuit, but Two-stage is consisted of PFC circuit, Buck-Inverter full bridge circuit. The Buck-Inverter full bridge inverter consists of two half bridge inverters for low frequency switching, and high frequency switching. In the case of street lamp it is far from a lamp to a ballast, the conventional pulsed high voltage ignitor can not turn on the HID lamps because of reduction of ignition voltage. Therefore, it needs to do the research on a resonant ignition to turn on the HID lamps. Therefore, in the Two-Stage electronic ballast which has the resonant tank for ignition, the transient resonant current because of low frequency changing is analyzed, the novel algorithm is proposed to resuce the transient current.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.1
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• pp.1-8
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• 2014

The conventional Three-Stage electronic ballast is stable, but Two-Stage electronic ballast has been researching because of efficiency. Three-Stage electronic ballast is consisted of PFC circuit, buck converter, and inverter circuit, but Two-stage is consisted of PFC circuit, Buck-Inverter full bridge circuit. The Buck-Inverter full bridge inverter consists of two half bridge inverters for low frequency switching, and high frequency switching. In the case of street lamp it is far from a lamp to a ballast, the conventional pulsed high voltage ignitor can not turn on the HID lamps because of reduction of ignition voltage. Therefore, it needs to do the research on a resonant ignition to turn on the HID lamps. Therefore, in the Two-Stage electronic ballast which has the resonant tank for ignition, the transient resonant current because of low frequency changing is analyzed, the novel algorithm is proposed to resuce the transient current.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.8-17
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• 2010

This paper proposes a novel LCD CCFL-backlight electronic ballast using the phase-shift full-bridge inverter. The proposed electronic ballast reduces the ignition voltage and eliminates current spikes using the new digital dimming control applied with soft-starting. Thus the electronic ballast improves ignition behavior of the CCFL and hence increases the CCFL's life span. For this, this paper analyzes the full-bridge inverter topology of the proposed electronic ballast and explains the new digital dimming control algorithm applied to the ballast, briefly. And this paper shows a design example of the prototype circuit and explains an implementation method of the digital dimming control which is implemented on a single-chip microcontroller with software. This was implemented as actual prototype electronic ballast, and its experimental results showed that the proposed electronic ballast operates correctly. The ignition voltage of the prototype in the digital dimming operation was reduced about 30[%] compared with the conventional electronic ballast and there were not any current spikes.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.3
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• pp.1-8
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• 2019

In this study, Arc plasma was employed for the thermal decomposition of nitrous oxide($N_2O$). Conventional ignition systems such as torch, spark, and catalyst systems, have disadvantages in that they are not reliable and do not provide rapid responses. Therefore, this study suggests the plasma application of plasma to overcome the problems of conventional ignition methods. A gas temperature and combustion experiment was carried out to investigate the feasibility to a novel igniter. The gas temperature was measured around $960^{\circ}C$ at 1 g/s, 0.7 A at the nearest wall. In addition, a combustion test was successfully conducted in 3.1 sec after the plasma discharge was initiated with a main flow rate of 10 g/s. The energy consumption for ignition was 1,780 J(574 W).

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.601-604
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• 2004

Precise position and attitude control of pico-satellite requires huge number of impulses of the order of 10$^{-6}$ Ns. MEMS solid rocket array is a promising propulsion system but the higher degree of miniaturization causes unreliable operation mainly due to quenching. In order to breakthrough this situation, a novel design of solid micro-rocket is proposed, which generates tiny impulses repetitively from a single rocket not from array. This unique micro-rocket is based on the utilization of quenching, which causes propellant reaction to sustain only in a small area. A test chip of a micro solid propellant tank and micro heater array is fabricated and ignition test is conducted. Obtained results show the feasibility of this concept and future direction of this quenching-based propulsion is discussed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.506-510
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• 2008

Ramjets are capable of much higher specific impulse than liquid rocket engines for high speed flight in the atmosphere. Ramjets, however, cannot generate thrust at low flight speed. Therefore, an additional propulsion device to accelerate the ramjet vehicle to a supersonic speed is required. In this study, we propose a novel ramjet propulsion system with a $H_2O_2$/Kerosene rocket as the accelerator for initial stage. In order to test the feasibility of this concept, consecutive reactors was built; one for the decomposition of $H_2O_2$ and the other for kerosene combustion. Decomposed $H_2O_2$ jet was injected to combustor through converging nozzle from gas generator and over this hot oxygen jet, kerosene was injected by spay injector. Through the various test cases, hypergolic ignition test was carried out and steady combustion was achieved.