• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.5
• /
• pp.627-633
• /
• 2001

Characteristics of a diesel spray impingement with the variation of ambient temperature, wall temperature and ambient pressure were investigated through shadowgraphy method by using high speed camera. The radial penetration of spray was increased with ambient temperature and wall temperature. It is resulted from the decrease of ambient gas density caused by the increase of temperature. The height of spray was also increased with ambient temperature and wall temperature, because the height of stagnate region is noticeably increased, although height of wall jet vortex is decreased. At the same ambient pressure, the area ratio of impinging spray of room temperature environment to high temperature environment was increased, as the temperature difference between room temperature and high temperature increases. And the increment of area ratio was higher at low ambient pressure than high ambient pressure.

• Asian-Australasian Journal of Animal Sciences
• /
• v.13 no.5
• /
• pp.625-629
• /
• 2000

Six yearling Suffolk ewes were used to study the effect of different roughage proportion diets (30%=LR, and 70%=HR) and intake levels (0.7 M and 1.3 M) on heat production and thermoregulatory responses in sheep exposed to different ambient temperatures (20 and $30^{\circ}C$). Sheep fed HR had higher heat production (HP) and time spent eating (TSE) and lower time spent standing (TSS) than those fed LR. But effect of roughage proportion on vaginal temperature (Tv) was obvious only at high intake and at $30^{\circ}C$. Sheep fed high intake had higher Tv, HP, TSS, and TSE than those fed low intake. Roughage proportion and intake level did not have an effect on respiration rate (RR), but ambient temperature did. Ambient temperature did not have an effect on HP, TSS and TSE. At $30^{\circ}C$ sheep had higher Tv and RR than those at $20^{\circ}C$. There were interactions between intake level and ambient temperature in TSS, between intake level and roughage proportion in TSE, and between roughage proportion and ambient temperature in HP. Results indicate that high roughage diet imposes a greater potential heat load on animals than low roughage diet when given at high ambient temperature, but not at low ambient temperature. And the effects is more pronounced at high intake.

• Journal of Information Display
• /
• v.4 no.4
• /
• pp.25-32
• /
• 2003

One of the important problems in ac PDP in recent years is the misfiring of ac PDP at high ambient temperatures which consequently degrades the image quality of the ac PDP. This may be due to the change of working gas pressure and/or MgO surface characteristics at high ambient temperatures. This paper deals with the effect of working gas pressure on the misfiring of ac PDP at high ambient temperature. From this study, we found that the main cause of the misfiring at high ambient temperature is the increase in discharge firing voltage induced by increased working gas pressure

• Journal of ILASS-Korea
• /
• v.21 no.1
• /
• pp.29-36
• /
• 2016

The effect of high ambient temperature and pressure conditions on the combustion performance of n-butanol, n-heptane and its mixing fuel (BH 20) were studied in this work. To reveal this, the closed homogeneous reactor model applied and 1000-1200 K of the initial temperature, 20-30 atm of initial pressure and 1.0 of equivalence ratio were set to numerical analysis. It was found that the results of combustion temperature was increased and the ignition delay was decreased when the ambient conditions were elevated since the combustion reactivity increased at the high ambient conditions. On the contrary, under the low combustion temperature condition, the combustion pressure was more influenced by the ambient temperature in the same ambient conditions. In addition, the total mass and the mass density of tested fuels were influenced by the ambient pressure and temperature. Also, soot generation of mixing fuel was decreased than n-heptane fuel due to the oxygen content of n-butanol fuel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.10
• /
• pp.1125-1131
• /
• 2004

Misfiring is usually observed at high ambient temperature in plasma display panel (PDP). This leads to bad image quality and limits the productivity of PDP industry. In this paper, experimental observations and improvement on the misfiring at high ambient temperature have been studied. In order to reduce the high ambient temperature misfiring different slope of ramp erase pulse corresponding to the temperature are applied. The experimental results show that the suggested method is quite effective for reducing the high temperature misfiring phenomena.

• The Research Journal of the Costume Culture
• /
• v.10 no.6
• /
• pp.793-801
• /
• 2002

The effects of ambient air temperature on the clothing ventilation were investigated numerically by a finite difference method. Numerical analysis using a 2-dimensional model comprising the air space between the skin and the clothing was conducted under the assumption that the clothing ventilation occurred only through the openings not through the fabric. The larger the temperature difference between the skin and the surroundings, the more apparent the thermal boundary layer As the ambient air temperature decreased, the air flow and the rate of the return of oxygen concentration to the atmosphere level in the clothing increased. Convection was dominant under low ambient air temperature, whereas conduction was dominant under high ambient air temperature. The ventilation rate was faster in the clothing microenvironment of the body part than that of the arm part.

• Journal of Biosystems Engineering
• /
• v.25 no.4
• /
• pp.273-278
• /
• 2000

The hybrid heat pump system of the air to air and / or air to water was composed and its COP was analyzed with the ambient temperature on the opened and closed loop system respectively. The results be indicated by the equation(7) that the COP(Coefficient of Performance) of air-source(air to air and / or air-water) heat pump is effected with the ambient air temperature and AVACTHE.(Automatic Variable Area Capillary Type Heat Exchanger) 2. The COP of air-to-water heat pump without AVACTHE decreased in accordance with the ambient temperature decrease, however in case of the heat pump with AVACTHE the COP was maintained at 2.8∼3.0 level when the ambient temperature decrease from -$5^{\circ}C$ to $-11^{\circ}C$. 3. The COP of the air-to-water heat pump operated on the open loop was higher 40∼58% than that of the heat pump operated on the close loop. 4. The lower ambient temperature air effect on the COP of the air-to-air heat pump operated on the semi closed loop could be controlled using the AVACTHE, and at the high ambient air temperature the COP increased using the Bypass circuit.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.946-951
• /
• 2001

This experimental study is to investigate the intermittent spray characteristics of a pintle nozzle. High speed camera used in this expreiment with 9000fps. The factor, which controls the diesel spray, is the Injection pressure, ambient pressure and ambient temperature. In this paper, experiments were conducted free spray for the ambient pressure(3, 4, 5Mpa), nozzle Injection pressure(10, 14, 18MPa) and ambient temperature(293, 473K). With the higher opening pressure, the spray tip velocity and spray penetration increases while the spray angle decreases, On the other hand, With the higher ambient pressure, the spray angle increase while the spray tip penetration and spray tip velocity decrease. also, With the higher ambient temperature, the spray penetration decrease while the spray angle decrease.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1999.12a
• /
• pp.211-218
• /
• 1999

The ambient air is commonly used as low-temperature heat sources for heat pump operation. However, the coefficient of performance (COP) of the air -water heat pump is decreased with the ambient air temperature drop. In this study to solve this problem , the AVACTHE(Automatic Variable Area Capillary Type Heat Exchanger) with 3 levels of heat exchange area(0, 1495.4, 1794.5$\textrm{cm}^2$) was installed in the refrigerant circuit of the heat pump. The AVACTHE effect on the performance of heat pump was tested with the ambient air temperature variation. The high level COP of the heat pump could be achieved by the AVACTHE installation when below -5$^{\circ}C$ of the ambient air temperature.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.65 no.4
• /
• pp.339-345
• /
• 2020

Recently, abnormal weather conditions, such as extreme high temperatures and droughts, have increased in frequency due to climate change, there has accordingly been growing concern regarding the detrimental effects on field crop, including soybean. Therefore, this study was conducted to examine the effects of increased temperatures on soybean growth and yield using a temperature gradient chamber (TGC). Two major types of soybean cultivar, a medium- seed cultivar such as Daepung-2 and a large-seed cultivar such as Daechan, were used and four temperature treatments, aT+1℃ (ambient temperature+1℃), aT+2℃ (ambient temperature+2℃), aT+3℃ (ambient temperature+3℃) and aT+4℃ (ambient temperature+4℃) were established to examine the growth response and seed yield of each cultivar. Seed yield showed a higher correlation with seed weight (r=0.713***) and an increase in temperature affected seed yield by reducing the single seed weight. In particular, the seed growth rate of the large-seed cultivar (Daechan) increased at high temperature, resulting in a reduction in the number of days for full maturity. Our results accordingly indicate that large-seed cultivar, such as Daechan, is potentially vulnerable to high temperature stress. The results of this study can be used as basic data in the development of cultivation technology to reduce the damage caused by elevated temperatures. Also, further research is required to evaluate the response of each process contributing to seed yield production under high temperatures.