• 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.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.799-804
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• 1989

A new method for measuring optical phase changes of reflection beam from optical mirror is proposed. The optical phase change is liable to change with varying atmosphere conditions. This optical phase changes are measured against air pressure, temperature, humidity and CO$\_$2/ concentration variations. It is clarified that the optical phase changes are most effected by humidity change.

• Journal of Technologic Dentistry
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• v.14 no.1
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• pp.91-94
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• 1992

This study was made to change dimension of self-curing resin by various curing technics. Specimens were fabricated 45 by 7 curing method. Six measurements(distances AB,BC,CD, AD, AC, and BD) were made of mold section and recorded with micrometer(1/20 mm). The results of the experiment were as follows : 1. The air pressure cured specimens exhibited more distoration than the bench-cured, watercured, and monomer atmosphere-cured specimens(P < 0.05). 2. The water pressure cured specimens exhibited more distoration sphere-cured specimens (P < 0.(15).

• Journal of Ship and Ocean Technology
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• v.7 no.3
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• pp.1-12
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• 2003

The influence of nonlinear phenomena on the behavior of stationary forced flexural-gravity waves on the surface of deep water is investigated, when the perturbation of external pressure moves with near-resonant velocity. It is shown that there are three branches of bounded stationary solutions turning into asymptotic solutions of the linear problem with zero initial conditions. For the first time ice sheet destruction by turbulent fluctuations of atmosphere pressure in ice adjacent layer in wind conditions is studied.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.11a
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• pp.235-238
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• 2008

High-rise buildings with stack effect caused by the foreclosure, which significantly delayed the spread of a fire in effects of these stack effect driving force said. In this research on the stack effect of the lobby if the pressurization of the stairwell analysis of the pressure distribution of the CONTAMW. Overall, the pressurization of the lobby makes it stairwell amount of pressure(+) to the zone in pressure designed to prevent the spread of smoke control performance and found that, the way a normal state and sub-pressurization in the stairwell with stack effect of the turbulence Such as the formation of the upper flow, but, in the upper atmosphere with pressurization was formed by the underlying trend.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.100-107
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• 1999

The purpose of the study is to investigate the effect of H$_2$ pressure on partial discharge (PD) activity and aging rate in turbine generator winding insulations. A series of field tests and laboratory tests were peformed to investigate the effect of $H_2$ pressure on PD activity. Field tests were conducted at two unit turbine generators in two conditions, in $H_2$ pressure and in air atmosphere. Obtained results are as follows ; 1) ${\Delta}tan{\delta}$ and maximum partial discharge are reduced with increase of $H_2$ pressure and partial discharge inception voltage. 2) The reduction ratio of ${\Delta}tan{\delta}$ due to $H_2$ pressure is higher than one of PD magnitude. 3) Partial discharge pulses suffer from attenuation and distortion when transmitted along windings, because of the complex L-C network between windings. From the result, partial discharge pulses are subjected to resonance phenomena in a generator winding.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.106-118
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• 2001

A rigorous study of single droplet vaporization under quiescent high pressure atmosphere is attempted adopting method of flash evaporation calculation for vapor-liquid equilibrium. Results due to flash method shows excellent agreement with measurement. Also shown is the present model fairly capable of depicting transients of droplet vaporization under high pressure environment, such as ambient gas solubility, property variation, and multicomponent transports. Systematic treatment of these effects with emphasis on vapor-liquid phase equilibrium revealed; conventional treatment for subcritical droplet vaporization, such as $d^2$-law, leads to erroneous prediction of droplet history, augmented gas solubility is significant under supercritical pressure, and vaporization rate proportionally increase with pressure.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.170-175
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• 2013

For this study, the domestically developed bootstrap reservoir of the aircraft is set up in accordance with the temperature and humidity conditions depicted on the qualification test, and the variation in the internal pressure of the bootstrap reservoir of the aircraft is examined. The study shows that the bootstrap reservoir has less variation in the internal pressure at room temperature than at low temperature($-40^{\circ}C$). As a result, the internal pressure can be maintained stably when the temperature of working fluid in the bootstrap reservoir and the atmosphere environment is over room temperature($25^{\circ}C$). Therefore the keeping of temperature above room temperature is very important to operate the bootstrap reservoir of the aircraft properly.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.409-414
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• 2009

Since cryogens are stored at very low temperatures, the cryogenic storage systems are quite sensitive to heat leaks. Even though the vessel operated under sealed condition with vacuum insulation and reflective coatings are used, the heat leakage into the vessel is still unavoidable. Therefore, this paper concerns with numerical study of self-pressurization used to analysis the optimum design with the variation volume fraction, effect of heat flux and storage pressure of liquid nitrogen. The result shows that as the volume fraction increases, the pressure rise reduces and the relatively at atmosphere pressure is better than the higher one. In addition, higher heat flux leads the pressure rise increases faster than low one. The additional of heat pipe system to reduce the pressure rise rate also has been done. By this comparison, the optimum design for storage umbilical cord blood can be selected.

• Atmosphere
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• v.23 no.2
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• pp.187-204
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• 2013

This study analyzed the synoptic distribution and vertical structure about four cases of precipitation occurrences using NCEP/NCAR reanalysis data and upper level data of winter intensive observation to be performed by National Institute of Meteorological Research at Bukgangneung, Incheon, Boseong during 63days from 4 JAN to 6 MAR in 2012, and Observing System Experiment (OSE) using 3DVAR-WRF system was conducted to examine the precipitation predictability of upper level data at western and southern coastal regions. The synoptic characteristics of selected precipitation occurrences were investigated as causes for 1) rainfall events with effect of moisture convergence owing to low pressure passing through south sea on 19 JAN, 2) snowfall events due to moisture inflowing from yellow sea with propagation of Siberian high pressure after low pressure passage over middle northern region on 31 JAN, 3) rainfall event with effect of weak pressure trough in west low and east high pressure system on 25 FEB, 4) rainfall event due to moisture inflow according to low pressures over Bohai bay and south eastern sea on 5 MAR. However, it is identified that vertical structure of atmosphere had different characteristics with heavy rainfall system in summer. Firstly, depth of convection was narrow due to absence of moisture convergence and strong ascending air current in middle layer. Secondly, warm air advection by veering wind with height only existed in low layer. Thirdly, unstable layer was limited in the narrow depth due to low surface temperature although it formed, and also values of instability indices were not high. Fourthly, total water vapor amounts containing into atmosphere was small due to low temperature distribution so that precipitable water vapor could be little amounts. As result of OSE conducting with upper level data of Incheon and Boseong station, 12 hours accumulated precipitation distributions of control experiment and experiments with additional upper level data were similar with ones of observation data at 610 stations. Although Equitable Threat Scores (ETS) were different according to cases and thresholds, it was verified positive influence of upper level data for precipitation predictability as resulting with high improvement rates of 33.3% in experiment with upper level data of Incheon (INC_EXP), 85.7% in experiment with upper level data of Boseong (BOS_EXP), and 142.9% in experiment with upper level data of both Incheon and Boseong (INC_BOS_EXP) about accumulated precipitation more than 5 mm / 12 hours on 31 January 2012.