• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.1
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• pp.112-121
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• 2007

Grain filling is a crucial factor that determines grain yield in crops since it is the final process directly associated with crops' yield performance. Grain filling process can be characterized by the interaction of rate and duration of grain filling. This study was conducted, using 16 temperate japonica rice genotypes, with aims to (1) seek variations in grain filling duration and rate on area basis, (2) compare the contribution of grain filling duration and rate to grain yield, and (3) examine the influence of temperature and solar radiation for effective grain filling on grain yield in relation to grain filling duration and rate. Grain filling rate and duration exhibited highly significant variations in the ranges of $20.7{\sim}46.3\;g\;m^{-2}d^{-1}\;and\;11.2{\sim}35.5$ days, respectively, depending on rice genotypes. Grain yield on unit area basis was associated positively with grain filling duration but negatively with grain filling rate. Grain filling rate and duration were negatively correlated with each other. Final grain weight increased linearly with the rise in both cumulative mean temperature and cumulative solar radiation for effective grain filling. Higher cumulative mean temperature and cumulative solar radiation for effective grain filling were the results of longer grain filling duration, but not necessarily higher daily mean temperature and daily solar radiation for effective grain filling. Grain filling rate demonstrated an increasing tendency with the rise in daily mean temperature for effective grain filling but their relationship was not obviously clear. It was concluded that grain filling duration, which influenced cumulative mean temperature and cumulative solar radiation for effective grain filling, was the main factor that determined grain yield on unit area basis in temperate Japonica rice.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.2
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• pp.184-190
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• 1992

The combustion characteristics, ignition delay, p-t, dp/dt, Q-t of diesel oil and fish oil blended diesel oils was investigated according to pressure and temperature in a constant volume combustion bomb. The results are as follows: 1) The influence of temperature and pressure on the ignition delay was almost constant in high temperature, regardless of the blending rates, and the ignition delay was shortest in the 60% blend. 2) The maximum pressure was high in order of with pure diesel oil, with the 20% blend and the 60% blend. 3) The rate of pressure rise was high in order of with pure diesel oil, with the 20% blend and the 60% blend. The rate of maximum pressure rise was significantly higher with pure diesel oil than with two blends. 4) The amount of accumulative heat release was large in order of with pure diesel oil, with the 20% blend and the 60% blend.

• Journal of the Korean Society of Safety
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• v.15 no.4
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• pp.95-100
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• 2000

This study was performed in Hartmann type dust explosion apparatus in order to research the dust explosion characteristics of hydroxypropyl methyl cellulose(HPMC): minimum explosive limit, minimum ignition energy, limiting oxygen concentration, maximum explosion pressure, rate of pressure rise, etc. The samples of HPMC dust were distributed into 120-140 mesh, 170-230 mesh and 325 under, and the gap distance of the discharge electrode was setted up at 5mm. The experimental results were obtained as follows: (1) The minimum explosive limit for HPMC dust was founded at 180g/㎥. the minimum ignition energy at 9.8mJ and the limiting oxygen concentration at 12%. (2) The maximum explosion pressure of HPMC dust was $8.1kg/cm^2\;{\cdot}\;$abs at the concentration of $500g/m^3$ and the maximum rate of pressure rise was 203.98 bar/sec at the concentration of $480g/m^3$ for 325 under.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2348-2352
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• 2017

The electrical contact characteristics including temperature rise, contact resistance and arc erosion rate of the $Ag-SnO_2$ materials with increased $SnO_2$ content were investigated during the repeated make-and-break operations. The thickness of arcing melting layer reduces by half and the arc erosion rate decreases more than 70% under 10000 times operations at AC 10 A with the $SnO_2$ content increasing from 15 wt.% to 45 wt.%, on one hand, temperature rise and contact resistance increase obviously but could be reduced to the same order of conventional $Ag-SnO_2$ materials by increasing the contact force. The microstructure evolution and the effect of $SnO_2$ on the arc erosion, contact resistance were analyzed.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.519-520
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• 2011

In Gas Insulated Substation(GIS), Very Fast Transient Overvoltages(VFTOs) are generated by the switching operation of disconnector or circuit breaker and it is propagated to each component of GIS. Each component of GIS is modeled by lumped line model and distributed line model based on equivalent circuits. The various cases which can be operated and the various closing point-on-wave are considered. In this paper, magnitude and rate-of-rise of VFTO are simulated and analyzed by comparing the simulation results. Measurements are performed at transformer and circuit breaker.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.109-114
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• 2001

Explosive characteristics of the city gas were determined by using the gas explosion apparatues. The explosive range is determined between lower explosive limit of 5.0% and upper explosive limit of 15.3% at atmosphere and even though the oxygen concentration is decreased, lower explosive limit is not changed, but upper explosive limit is rapidly decreased. The minimum oxygen for combustion is determined 10%. The maximum explosion pressure is determined 5.72$\textrm{cm}^2$ and the maximum rate of explosion pressure rise is oxygen concentration of 12% to determined 160.12$\textrm{cm}^2{\cdot}$sec.

• Journal of the Korean Society of Safety
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• v.5 no.3
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• pp.51-55
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• 1990

This study describes the engineering approach adopted to investigate sprinkler head during the early stage of a fire when they are subjected to convective heating and low gas velocities. Comparions are made between the parameters derived using basic methods, ie. ramp test, for evaluating sprinkler parameters(time constant, response time index) is illustrated. Evidence is presented that the propotion of heat loss by conduction from a sprinkler element may very typically employed in the rate of rise test. This fact alone may justfy the precautionary need to perform a limited number of rate of rise tests to confirm a sprinklers capacity to function correctly in reasonably unfavourable yet realistic conditions. The work is aimed primarily at meeting the needs of sprinkler industry.

• Speech Sciences
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• v.6
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• pp.145-161
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• 1999

21 normal Korean native speakers participated as subjects to investigate the acoustic and aerodynamic study of Korean fricatives and affricates and to make good use of the results for the patients with articulation problems. Their productions of [sa], [s'a], [ca], [$c^{h}a$], [c'a], [asa], [as'a], [aca], [$ac^{h}a$], and [ac'a] were analyzed with CSL and AP II instruments. The results are as followings: (1) Fricatives showed higher frequency in minimum and maximum frequency and longer duration than affricates. (2) Fricatives showed higher peak flow rate and longer rise time than affricates. (3) When we compared the different phonemes with each other, their differences were usually statistically significant, but when we compared CV and VCV syllables, they did not show significant difference, even VCV's showed higher and longer values than CV syllables. (4) Normaly, lax fricatives and affricates showed lower frequency and higher peak flow rate, shorter frication duration, and longer rise time.

• Journal of Power System Engineering
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• v.13 no.4
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• pp.31-37
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• 2009

The purpose of this numerical study was to investigate performance characteristics for cooling tower axial fans with sweep. Performance data for the fans with various sweep angles were obtained in terms of the setting angle at a constant flow rate. Viscous flow calculations were carried out to obtain Performance data of the total pressure rise and hydraulic efficiency. A solution of the Ffowcs Williams-Hawkings equations was used to calculate the sound pressure level at three times fan diameter away from the fan. The calculated performance data well represented performance characteristics of the cooling tower axial fan. The total pressure rise and hydraulic efficiency at the same setting angle decreased with sweep angle. Sound pressure level slightly decreased for the fan with a sweep angle of 10 degree. No significant effect of the sweep geometry was found on the sound pressure level.

• 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.