• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.133-138
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• 2007

Influence of changing combustor pressure on flame stabilization and emission index in the swirl-stabilized flame was investigated The combustor pressure was controlled by suction fan at combustor exit. Pressure index ($P^{\ast}=P_{abs}/P_{atm}$), where $P_{abs}$ and $P_{atm}$ indicated the absolute pressure and atmosphere pressure, respectively, was controlled in the range of $0.7{\sim}1.3$ for each equivalence ratio conditions. The flammable limits of swirl flames were largely influenced by changing combustor pressure and they showed similar tendency with laminar flames. $NO_x$ emission index decreased with decreasing pressure index for overall equivalence ratio conditions. R.m.s. of pressure fluctuations is increased with decreasing combustor pressure. This flame fluctuation caused incomplete combustion , hence CO emission index increased. These oscillating flames were measured by simultaneous $CH{\ast}$ chemiluminescence time-series visualization and pressure fluctuation measurement.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2354-2359
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• 2007

Influence of changing combustor pressure on flame stabilization and emission index in the swirl-stabilized flame was investigated. The combustor pressure was controlled by suction fan at combustor exit. Pressure index ($P^{\ast}$=Pabs/Patm), where Pabs and Patm indicated the absolute pressure and atmosphere pressure, respectively, was controlled in the range of 0.7${\sim}$1.3 for each equivalence ratio conditions. The flammable limits of swirl flames were largely influenced by changing combustor pressure and they showed similar tendency with laminar flames. NOx emission index decreased with decreasing pressure index for overall equivalence ratio conditions. R.m.s. of pressure fluctuations is increased with decreasing combustor pressure. This flame fluctuation caused incomplete combustion, hence CO emission index increased. These oscillating flames were measured by simultaneous $CH^{\ast}$ chemiluminescence time-series visualization and pressure fluctuation measurement.

• The Journal of Korean Physical Therapy
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• v.22 no.2
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• pp.1-6
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• 2010

Purpose: Our study sought to investigate differences in plantar foot pressure as a function of type of pack carried and of changing weight during gait and stance. Methods: Subjects were 40 students with no disabilities. Plantar foot pressure was measured with different types of packs carried and with changing weight of the pack during both gait and stance and while changing feet. During stance while carrying a satchel on the shoulder caused a disproportionate change in plantar foot pressure. An even great imbalance occurred for plantar foot pressure during gait. Results: Using a satchel can influence diseases such as scoliosis that are caused by unbalanced muscle activation and by a disproportionate distribution of the weight of the body. Conclusion: Knowing how to use a pack correctly and how to appropriately adjust the weight of bag should be taught.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.128-133
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• 2006

Influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOx) emission in the swirl-stabilized flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P{\ast}=P_{abs}/P_{atm}$), where $P_{abs}$ and $P_{atm}$ indicated the absolute pressure and atmosphere pressure, was controlled in the range of $0.7{\sim}1.3$ for each equivalence ratio conditions. The flammable limits of swirl flames were largely influenced by changing combustor pressure and they showed different tendency compared with laminar flames. Emission index showed maximum value near atmospheric condition and decreased with decreasing pressure index for overall equivalence ratio conditions. R.m.s of pressure fluctuations also showed similar tendency with nitric oxide emission. By injecting secondary fuel into flame zone, the flammable limits were extended significantly. Emission index of nitric oxide and r.m.s. of pressure fluctuations were also controlled by injecting secondary fuel. The swirl flames were somewhat lifted by secondary fuel with high momentum, hence low nitric oxide emission. This NOx reduction technology is applicable to industrial furnaces and air conditioning system by adopting secondary fuel injection.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.275-280
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• 2005

At previous study, nitrogen oxide emission was decreased with decreasing pressure index. This tendency was explained by the flame oscillation with changing combustor pressure. In this study, the characteristics of flame oscillation with changing combustor pressure were investigated. It can be found that flame length is extended and flame width is narrowed by decreasing combustor pressure. It can be observed that pilot flame and the surrounding air converge on the inner flame in the $P^{\ast}{\geqq}1$ conditions and that surrounding air and flow pattern was widely dispersed in the $P^{\ast}<1$ conditions. In the respect of average flame length, low fluctuation was shown in the $P^{\ast}<1$ conditions. On the other hands, large fluctuation was shown in the $P^{\ast}<1$ conditions. Flame oscillation are observed from $P^{\ast}=$ 0.98 in the condition of $P^{\ast}<1$ and the amplitude of flame oscillation becomes larger when $P^{\ast}$ is lowered. These results demonstrate that low NOx phenomenon was caused by flame oscillation with changing combustor pressure.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.269-271
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• 2012

To investigate emission characteristics of laminar premixed CH4/air flame, combustion experiments were conducted at three flow rates (5.3L/min, 10.6L/min, 15.5L/min) with changing the combustor pressure(-30Kpa-30Kpa). It was found that with increasing flow rate, NOx emission increased in high pressure condition, while decreased in low pressure condition; and the emission of CO decreased with increasing flow rate. For the influence of pressure, emission of NOx increased with increasing pressure regardless of flow rates, while CO emission decreased on the contrary.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.10 s.241
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• pp.1148-1155
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• 2005

In this study, the influence of changing combustor pressure on nitric oxide emission was investigated. Expansion of reaction region was more clear in the P$^{*}$ <1 conditions compared to the P$^{*}\geq1$ conditions, and it could be observed that flames are distinct in the P$^{*}\geq1$ conditions and that brightness is relative low and wide distribution is shown in the P$^{*}$ <1 conditions. In the respect of temperature distribution, narrow and high-temperature region was shown in the P$^{*}\geq1$ conditions. On the other hands, overall uniform temperature distributions were shown in the P$^{*}$ <1 conditions. Nitric oxide emission decreased with decreasing combustor pressure. This tendency was explained by the mean flame temperature distribution. Low NOx combustion is ascribed to wide-spread reaction region in the low combustor Pressure and oscillation were shown P$^{*}\leq0.97$, and strength and sizes of oscillation were more increased with lower pressure index. These results demonstrate that flame shape and nitric oxide emission can be controlled with changing combustor pressure.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.569-572
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• 2006

In present study, the influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOX) emission in the swirl flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P^*=Pabs/Patm$), where Pabs and Patm indicated the absolute pressure and atmosphere pressure, was controlled in the range of 0.7~1.15 for each equivalence ratio conditions. It could be observed that flame stable region became narrower with decreasing equivalence ratio and pressure index. In this combustion system, stable flames were formed until $P^*=\;0.7$. Emission index decreased with decreasing pressure index for overall equivalence ratio conditions and NOx reduction rates were almost identical for $P^*<1$ regardless of equivalence ratio though EINOx values showed different level with change of equivalence ratio for $P^*{\geq}1$. It is also observed that EINOx decreased with increasing secondary fuel injection ratio. Emission index of nitric oxide was controllable by adjusting the changing combustor pressure and injecting secondary fuel and this NOx reduction technology is applicable to industrial furnaces and air conditioning system.

• Journal of the Korean Society of Combustion
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• v.14 no.4
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• pp.41-47
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• 2009

An experimental study was performed to confirm the effect of the changing combustor pressure(-30~30 kpa), combustion characteristics were investigated by measuring the local chemiluminescence intensity, the local temperature distribution and emission. In order to investigate combustion ones, the combustor pressure index($P^*$) was controlled in the range of 0.7~1.3 for each equivalence ratio in the present combustion system, where $P^*$ is defined as the ratio of absolute pressure to atmospheric one. The local mean temperature showed the uniform distributions for lower pressure index, which increased with increasing equivalence ratio. The mean $OH^*$ chemiluminescence intensity, showed high level for lower pressure index for ${\Phi}{\get}1.0$ conditions. EINOx decreased with decreasing pressure index for overall equivalence ratio conditions.

• Proceedings of the KSR Conference
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• 2002.05a
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• pp.228-233
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• 2002

The transition between bridge or tunnel and plain track has different rail pressure and distributed stress on formation. This paper shows distribution of rail pressure on transition at which spring stiffness are changed. By this study, it is revealed that the changing into relatively high stiffness causes increased rail pressure visibly and draw up dynamic track force. A medium stiffness structure and reinforced rail could be effective for reducing track force on the transition.