• 한국연소학회:학술대회논문집
• /
• 2012.04a
• /
• pp.7-8
• /
• 2012

The effects of interaction between partially premixed and premixed swirl flames on CO and NOx emissions were experimentally investigated using a hybrid/dual swirl jet combustor for a micro-gas turbine. Under the condition of constant angle ($45^{\circ}$) for outer swirl vane, the angle and direction of inner swirl vane installed for a partially premixed flame were varied as main parameters with a constant fuel flow rate for each nozzle. It was found that for all conditions, CO and NOx emissions were measured below 4 ppm and 15 ppm at 15% $O_2$, respectively, in a wide range of equivalence ratio (0.6~0.9). For co-swirl flows, CO emission increased dramatically as the angle of inner swirl vane increased from $15^{\circ}$ to $45^{\circ}$ near lean-flammability limit (i.e. equivalence ratio of 0.5). On the other hand, the case of swirl $angle=45^{\circ}$ provided the lowest NOx emission at higher equivalence ratios than 0.6. For counter-swirl flows, the case of swirl $angle=45^{\circ}$ extended the lean-flammability limit but higher NOx emissions were found compared to those of co-swirl flows. These results could be inferred by interaction between (inner) partially premixed and (outer) premixed swirl flames. However, these estimations were not clear yet because there was insufficient data on turbulent flow structure and fuel-air mixing in the present experimental approach.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.16 no.3
• /
• pp.66-72
• /
• 2008

Fuel reforming technology for the fuel cell vehicles could be adopted to internal combustion engine for the reduction of engine out emissions. Since syngas which is reformed from fossil fuel has hydrogen as a major component, it has abilities to enhance the combustion characteristics with wide flammability and high speed flame propagation. In this paper, syngas was feed to 2.0 liter gasoline engine during the cold start and early state of idle condition. Not only cold start HC emission but also $NO_x$ emission could be dramatically reduced due to the fact that syngas has no HC and has nitrogen up to 50% as components. Exhaust gas temperature was lower than that of gasoline feeding condition. Delayed ignition timing, however, resulted in increased exhaust gas temperature approximated to gasoline condition. It is supposed that the usage of syngas in the gasoline internal combustion engine is an effective solution to meet the future strict emission regulations by the reduction of cold start THC and $NO_x$ emissions.

• Fashion & Textile Research Journal
• /
• v.6 no.5
• /
• pp.565-574
• /
• 2004

The purpose of this study is to investigate the historical background and basic composition of costume of the Baekje period. Main official hats of Baekje include the transformed hat, jougwan and daeryun-style ipsikgwan. Daeryun-style ipsikgwan employed chowha shape in most cases, symbolizing good auspice under the harmony of the male and female principles. Main types of costume of the Baekje period are po, yu, go and sang. The king, governmental officials and the common people all put on po of jikryeong gyoim style. Yu' is classified into two styles, chaksu with the narrow sleeve and daesu with the broad one. 'Go' has two styles, gunggo and gwango. The former is narrow in the breadth of the trouser and the latter, wide. 'Sang' is classified into various style according to whether it contains stripes of many colors, thin wrinkles or thick wrinkles. For the decoration of official hat used in the period of the Three Kingdoms, Baekje employed chowha in shape, Kokuryo, chowha and joik and Shilla, joik. In Baekje, rhythmic patterns of flame were applied to official hats, presenting brilliance. In Shilla, shaking geumyeongrak was used for official hats to show movement. In Kokuryo, such hats used flapping feathers, symbolizing dynamic power. Most necklaces and bracelets of the Baekje period were simple and plain.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.3
• /
• pp.174-182
• /
• 2007

Fuel reforming technology for the fuel cell vehicles could be applied to internal combustion engine for the reduction of engine out emissions. Since syngas which is reformed from fossil fuel has hydrogen as a major component, it has abilities to enhance the combustion characteristics with wide flammability and high speed flame propagation. In this study, syngas was added to a gasoline engine to improve combustion stability and exhaust emissions of idle state. Syngas fraction is varied to 0%, 50%, 100% with various ignition timing and excess air ratio. Combustion stability, exhaust emissions, fuel consumption and exhaust gas temperature were measured to investigate the effects of syngas addition on idle performance. Results showed that syngas has ability to widely extend lean operation limit and ignition retard range with dramatical reduction of engine out emissions.

• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.807-814
• /
• 1995

Accurate measurements of ozone precursors are required to understand the process and extent of ozone formation in rural and urban areas. Nonmethane hydrocarbons (NMHCs) have been identified as important ozone precursors. Identification and quantification of NMHCs are difficult because of the large number present and the wide molecular weight range encountered in typical air samples. A major plan of the research team of the Climate and Air Quality Taiwan Station (CATs) was the measurement of atmospheric nonmethane hydrocarbons. An analytical method has been development for the analysis of the individual nonmethane hydrocarbons in ambient air at ppb (v) and subppb(v) levels. The whole ambient air samples were collected in canisters and analyzed by GC-FID with $Al_2O_3$/KCl PLOT column. Our targeted for quantitative analysis 43 compounds that may be substantial contributors to ozone formation. The retention indices and molar response factors of some commercially available $C_2{\sim}C_{10}$ hydrocarbons were determined and used to identify and quantify air samples. A quality assurance program was instituted to ensure that good measurements were made by participating in the International Nonmethane Hydrocarbon Intercomparison Experiments (NOMHICE).

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.8
• /
• pp.43-54
• /
• 1999

The effects of equivalence ratio and pressure on burnt gas temperature in premixed fuel rich propane-oxygen-inert gas combustion are investigated over the wide ranges of equivalence ration from 1.5 to 2.7 and pressure from 0.1 to 7 MPa by using a specially designed disk -type constant-voume combustion chamber, The premixtures are simultaneously ignited by eight spark plugs located on the circumference of combustion chamber with 45 degree interals. The eight converging flames compress the end gases to high pressures. The burnt gas temperature is meausured by the nmodifie dtow-colr pyrometry method. The transmissivity in the chamber center during the final stage of combustion at the hightest pressure is meausred by in situ laser extinction method. It is found that a temperature difference between the burnt gas temperature measured by mofidied and conventrational two-color method is 10 to 20 K, but the accuracy of the modified two-color methdo is higher if the local transmissivity in observed region is uniform , and the combustion at higher pressures results gas density conditions and the burnt gas temperature increases as the volume fraction of argon is increased because the specific heat of argon is lower compared to that of nitrogen with a constant equivalence ratio.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.2
• /
• pp.115-128
• /
• 2006

A technical analysis of current scramjet and combined-cycle engine is presented. Substantial research has been pursued to characterize the operation mechanism of scramjet propulsion, especially in the areas of flame stabilization and system integration, dramatically over the years in support of both military and space access application. Major technology that had significant impact on the maturation of scramjet propulsion technology are dual combustion ramjet, dual mode ramjet, and combined cycle engine to cover a typical wide rage of flight, up to flight Mach number 10. Notable are the fundamental and practical techniques, for instance, scram propulsion itself, thermal relaxation and protection using endothermic fuel and/or CSiC composit materials, and design/manufacture of movable intake and nozzle, to realize high speed propulsion system in near future.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.8
• /
• pp.508-513
• /
• 2017

Ultraviolet (UV) photodetectors are used in various industries and fields of research, including optical communication, flame sensing, missile plume detection, astronomical studies, biological sensors, and environmental research. However, general UV detectors that employ Schottky junction diodes and p-n junctions have high fabrication cost and low quantum efficiency. In this study, we investigated the characteristics of materials used to manufacture UV photodetectors in a low-cost solution process that requires easy fabrication of flexible substrates. We fabricated p-type NiO and n-type ZnO substrates with wide band gap by the sol-gel method and compared the characteristics of substrates prepared under different spin-coating and heat-treatment conditions.

• Toxicological Research
• /
• v.33 no.4
• /
• pp.299-304
• /
• 2017

Thallium and its compounds are a class of highly toxic chemicals that cause wide-ranging symptoms such as gastrointestinal disturbances; polyneuritis; encephalopathy; tachycardia; skin eruptions; hepatic, renal, cardiac, and neurological toxicities; and have mutagenic and genotoxic effects. The present research aimed to evaluate the efficacy of the chelating agents deferasirox (DFX) and deferiprone (L1) in reducing serum and tissue thallium levels after the administration of thallium (III), according to two different dosing regimens, to several groups of Wistar rats for 60 days. It was hypothesized that the two chelators might be more efficient as a combined therapy than as monotherapies in removing thallium (III) from the rats' organs. The chelators were administered orally as either single or combined therapies for a period of 14 days. Serum and tissue thallium (III) and iron concentrations were determined by flame atomic absorption spectroscopy. Serum and tissue thallium (III) levels were significantly reduced by combined therapy with DFX and L1. Additionally, iron concentrations returned to normal levels and symptoms of toxicity decreased.

• Journal of the Korean Burn Society
• /
• v.24 no.2
• /
• pp.46-49
• /
• 2021

An anatomically normal first web space is essential for optimal prehensile movements of the thumb and hand. A 28-year-old woman presented with severe scarring and contractures of the first web space of both hands, following a flame burn injury sustained 25 years prior to presentation. First web space contracture may occur secondary to severe injuries, burns (as observed in our patient), or congenital hand anomalies. A significant amount of additional skin is required to release a severe first web space contracture. Reconstruction of wide areas of contractures using only local flaps is challenging. Among other free flaps used in clinical practice, the thinned lateral arm free flap provides flexible vascularized tissue for reconstruction of the skin after severe first web space contracture release. Reconstruction using lateral arm free flaps facilitated thumb abduction and opposition (which were initially difficult) and improved hand function in our patient.