• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.85-90
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• 1996

석탄 직접연소의 신기술인 Cyclone 연소기술은 환경오염저감 기술증의 하나로서, 고온 연소로 인해 회분이 연소실 내부에서 용융, 제거된 후 고온의 청정연소가스만 보일러로 유입된다. 또한 연소기의 fuel-rich 연소조건하에서 생성된 고온의 불완전연소가스는 보일러 입구에서 충분한 재연소공기를 공급함으로서 완전연소시킬 수 있으므로 적은 시설투자 비용으로 기존 오일이나 가스용 보일러를 석탄용으로 전환이 용이할 뿐만 아니라 이러한 다단 연소방식을 채택하여 NOx 제어도 가능하다는 이점이 있다. Cyclone 연소기술의 개발은 석탄의 청정연소 뿐만 아니라 그 기술을 토대로 석탄가스화, MHD 발전, 가연성 폐기물 소각등에도 활용할 수 있다. 따라서 국내 기술자립을 위해 실험용 Cyclone 연소기를 설계, 제작 및 연소실험을 수행한 결과, Peco-semi탄을 연료로 공급량 약 30 kg/hr, 공기비 약 1.0 일 때 탄소전환율은 약 95% 이며 회분제거율은 약 70%임을 확인할 수 있었다.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.17-22
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• 2001

This paper is the first of companion papers, which investigate port-masking effects on lean misfire limit. Port-masking was applied to commercial SOHC 3-valve and DOHC 4-valve engine by inserting masking plates between manifold and port. To induce various conditions of stratification, six types of masking plates were applied. The masking plates were placed in the upstream of injector to prevent wall wetting and two ports were not separated to permit both fuel and air entering through masked port. The results were compared with those by conventional port throttling. The results show that lean misfire limit mainly depends on masking direction, that is, high lean misfire limit is achieved when the port near the spark plug is masked. The mechanism of stratification by masking is different from axial stratification by port throttling. In this case, the rich mixture entering through masked port plays a very important role in the stratification process.

• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.105-115
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• 1999

The structure of a non-axisymmetric propane diffusion flame was investigated. Tomographic reconstruction method to convert the line-integrated self-emission data of a fuel-rich diffusion flame with square cross-section was applied to get the spatially reconstructed emission data. Modified Shepp-Logan filter and concentric squares raster were chosen for reconstructing arbitrarily shaped object in this process. Spatially reconstructed emission data were then interpreted to several physical quantities, such as flame edge, FWHM, perimeter and 3-D flame temperature distribution. Necessary assumptions were discussed and the results were interpreted. In comparison with axisymmetric flame, flame edge was developed higher, and sooting region of upstream was broader than in this non-axisymmetric one. At some height, the flame was shrunk very rapidly and finally formed circular cross-section.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.10
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• pp.767-772
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• 2009

The demand for a boiler with low NOx burner is increasing with the recent strict NOx regulation. Staged burner is a common low NOx burner to suppress the formation of thermal NOx by yielding local fuel rich and lean condition. The staged burner gives fire with bigger frontal area and length compared with a conventional burner, which changes heat transfer characteristics in the combustion chamber. The heat transfer and exhaust gas characteristics have been studied in the present study for a 0.5 t/h class furnace type boiler adopting the staged burner. A numerical simulation has been conducted to clarify the detailed physics inside the combustion chamber.

• Journal of Energy Engineering
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• v.6 no.2
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• pp.162-169
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• 1997

The particle size effect on the combustion characteristics of pulverized coal was investigated in the cylindrical-shape, horizontal furnace, fired in the range of 8.8∼10.6 kw. Three differently-sized fractions (5, 30, and 44 microns in average diameter) of high-volatile bituminous coal, were burned in the test furnace. Burnout behavior of pulverized coal flame were determined through the measurement of stable species concentrations (CO$_2$and H$_2$O). Concentrations of CO$_2$were compared with the theoretical values and the result showed good agreement. Thermal behavior of pulverized coal flame were determined as maximum flame temperatures occurred at fuel-rich conditions in every case. Flame lengths were also determined by decreasing with the particle size decrease. The flame length of the fine sized coal sample was comparable to that produced by distillate oil. The color of the coal flames ranged from orange to yellow, with the flame of the fine size fraction being brighter and yellower than the others.

• Journal of the Korean Society of Combustion
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• v.4 no.2
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• pp.85-95
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• 1999

The objective of this study was to obtain basic data for the staged combustion toward the NOx reduction in coal combustion. Combustion and NOx emission/reduction were investigated by using DTF. NOx emission was decreased with decreasing air ratio and with increasing volatile content in coal. In particular, effective NOx reduction was achieved at high temperature at the onset of combustion with fuel rich condition.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.767-779
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• 2017

Automated mission planning for unmanned aerial vehicles (UAVs) is difficult because of the propagation of several sources of error into the solution, as for any large scale autonomous system. To ensure reliable system performance, we quantify all sources of error and their propagation through a mission planner for operation of UAVs in an obstacle rich environment we developed in prior work. In this sequel to that work, we show that the mission planner developed before can be made robust to errors arising from the mapping, sensing, actuation, and environmental disturbances through creating systematic buffers around obstacles using the calculations of uncertainty propagation. This robustness makes the mission planner truly autonomous and scalable to many UAVs without human intervention. We illustrate with simulation results for trajectory generation of multiple UAVs in a surveillance problem in an urban environment while optimizing for either maximal flight time or minimal fuel consumption. Our solution methods are suitable for any well-mapped region, and the final collision free paths are obtained through offline sub-optimal solution of an mTSP (multiple traveling salesman problem).

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.149-154
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• 1999

The influences of air staging on NOx emission and burnout of coal flames were investigated using 1MWth combustion test facility. The experiments showed that variation of overall excess air ratio led to a relatively higher NOx emission level for ${\lambda}=1.2.$ When air staging was applied to the combustion air, it was confirmed that a fuel rich primary combustion zone was established and unburned char was burened completely by mixing with the staged air supplied radially around the flame. The NOx emissions were redued by increasing the staged air flow rate, and staging air was suggested to be more than 40% of the total combustion air for the substantial NOx reduction.

• Journal of the Korean Chemical Society
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• v.4 no.1
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• pp.62-66
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• 1957

With the intention of preparing cation exchangers from the domestic coals, and using these for softening hard water and some other purposes, seven kinds of raw coal were tested and the results are as follows. 1) The following conditions of preparation were given the good results. Reaction time 5 hours Reaction temperature $95^{\circ}$ Concentration of sulfuric acid 98% Amount of sulfuric acid 10 times to the sample (as weight) 2) The raw coals which is rich in fixed carbon and have the fuel ratio 0.8 to 1.0 were suitable, and Kampo lignite has shown the best results. 3) The cation exchangers from coals were able to exchange the cation, both hydrogen and sodium type dynamically and statically, like the synthetic ion exchange resin. The exchange capacities were as follows. Total capacity 1.60 meq/g. Breakthrough capacity 1.30 meq/g. Usable breakthrough capacity 1.20 meq/g National Central Research laboratory

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.217-220
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• 2009

This paper presents experimental results of Recess Characteristic of Swirl Coaxial Injector of fuel-rich gas generators. It was revealed that the internal impinging phenomenon played an important role in the spray characteristics, such as spray angle and breakup length.