• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.22-31
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• 1993

Spark-ignition engine knock is affected by engine operating conditions such as engine speed, spark timing and intake air temperature. In this study the effect of intake air temperature on knock characteristics was studied experimentally using a 4-cylinder carburetor spark-ignition engine. The cylinder pressure data at 2000rpm were taken for intake air temperature range of $30^{\circ}C$ to $80^{\circ}C$ with $10^{\circ}C$ interval. And 80 consecutive cycles were taken at each experimental condition. As the same spark timing, as the intake air temperature increased by $50^{\circ}C$, the mean knock intensity increased about 20kPa. This effect corresponds to that of spark timing advance of 3 crank angle degrees.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.93-94
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• 2008

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.740-750
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• 2003

It has been observed that the cooling capacity of an impinging water jet is affected by the seasonal conditions in large-scale steel manufacturing processes. To confirm this phenomenon, cooling experiments utilizing a hot steel plate cooled by a laminar jet were conducted for two initial ambient air temperatures (10$^{\circ}C$ and 40$^{\circ}C$) in a closed chamber, performing an inverse heat conduction method for quantitative comparison. This study reveals that the cooling capacity at an air temperature of 10$^{\circ}C$ is lower than the heat extracted at 40$^{\circ}C$. The amount of total extracted heat at 10$^{\circ}C$ is 15% less than at 40$^{\circ}C$ , These results Indicate the quantity of water vapor, absorbed until saturation, affects the mechanism of boiling heat transfer.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.8
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• pp.722-728
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• 2005

The present paper deals with heating energy estimation in Korean-style apartments, paying special attention to the effect of room condition settings. Two types of heating modes are considered: continuous single-zone and scheduled multi-zone. In the latter, zones during unoccupied periods remain unconditioned. Also analyzed are sensitivities in heating energy with respect to the air change rate and the set temperature. The energy use is estimated with TRNSYS 15, a dynamic load calculation program. Heating energy for the actual residential condition (1.0 ACH and $24^{\circ}C$) appears to be nearly the same as that for a typical design standard (1.5 ACH and $20^{\circ}C$). The air change rate affects heating energy as sensitive]y as the set temperature. For all the simulated cases, the scheduled multi-zone heating mode is more energy-efficient than the continuous single-zone. Heating energy depends appreciably on the shading factor. It is expected that considerable heating energy for apartment houses can be saved by employing a multi-zone mode along with appropriate control devices.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.326-331
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• 2018

Evaporative humidification using a humidifying element is used widely for the humidification of a building or a data center. The performance of a humidifying element is commonly expressed as the humidification efficiency, which is assumed to be independent of the air temperature or humidity. To verify this assumption, a series of tests were conducted under two air conditions - data center ($25^{\circ}C$ DBT, $15^{\circ}C$ WBT) and commercial building ($35^{\circ}C$ DBT, $21^{\circ}C$ WBT) - using humidifying elements made from cellulose/PET and changing the frontal air velocity from 1.0 m/s to 4.5 m/s. Three samples having a 100 mm, 200 mm, or 300 mm depth were tested. The results showed that the humidification efficiency is dependent on the air condition. Indeed, even dehumidification occurred at the inlet of the humidifying element at the air condition of commercial building. This suggests that a proper thermal model should account for the inlet area, where the amount of moisture transfer may be different from the other part of the humidification element. As the depth of the element increased from 100 mm to 200 mm, the humidification efficiency increased by 29%. With further increases to 300 mm, it increased by 42%. On the other hand, the pressure drop also increased by 47% and 86%.

• The Korean Journal of Ecology
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• v.23 no.4
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• pp.293-298
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• 2000

To study the effect of global warming on the growth of plants and plant populations throughout their life cycle under a field-like condition, we constructed a Temperature Gradient Chamber (TGC) in Tsukuba, Japan. The chamber had slender shape : 30 m long. 3 m wide, and 2.5 m high. That satisfactory performance was confirmed by a test throughout all seasons in 1998: the projected global warming condition in the near future was simulated. That is, independent of a great daily or seasonal change in ambient meteorological conditions, air temperatures at the air outlet were warmed 5$^{\circ}C$ higher than those at the ambient (the annual mean was 14.3$^{\circ}C$) with precision of ${\pm}$0.2$^{\circ}C$ (the annual means were 19.2$^{\circ}C$) with a rising rate of approximately 1$^{\circ}C$ every 5 m. This chamber will enable us to study the effects of global warming on growth of plants and plant populations because their abilities to control air temperature are excellent. TGC is expected that it would be utilized for studying the effect of global warming on plant growth under natural weather conditions.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.1
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• pp.13-22
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• 2004

This study presents the thermal analyses of a spent fuel dry storage cask under normal and off-normal conditions. The environmental temperature is assumed to be 15 $^{\circ}C$ under the normal condition. The off-normal condition has an environmental temperature of 38 $^{\circ}C$. An additional off-normal condition is considered as a partial blockage of the air inlet ducts. Two of the four air inlet ducts are assumed to be completely blocked. The significant thermal design feature of the storage cask is the air flow path used to remove the decay heat from the spent fuel. Natural circulation of the air inside the cask allows the concrete and fuel cladding temperatures to be maintained below the allowable values. The finite volume computational fluid dynamics code FLUENT was used for the thermal analysis. The maximum temperatures of the fuel rod and concrete overpack were lower than the allowable values under the normal and off-normal conditions.

• Journal of agriculture & life science
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• v.43 no.3
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• pp.27-34
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• 2009

Green tea was prepared by soaking 1.5 g of green tea leaves into 100 mL of distilled water at $75^{\circ}C$ for 5 min. The green tea was stored at three different conditions - (A) green tea was stored at not-artificially excluding natural light condition, at natural air condition, and without addition of vitamin C; (B) green tea was stored at artificially excluding natural light condition by wrapping a vial with aluminium foil, at nitrogen filling up condition, and with addition of 30 mg/100 mL of vitamin C; and (C) green tea was stored at artificially excluding natural light condition by wrapping a vial with aluminium foil, at nitrogen filling up condition, and without addition of vitamin C. After 28 days of storage at $4^{\circ}C$, the chemical quality of the green tea was evaluated. Total phenolic contents of (A), (B), and (C) green tea decreased to 71.50, 73.88 and 75.07%, respectively, after storing for 28 days compared to those of beginning state. DPPH radical scavenging activities of (A), (B), and (C) green tea were 87.87, 92.93 and 88.39%, respectively. Epigallocatechin gallate (EGCG), the main active compounds of green tea, contents of (A), (B), and (C) green tea were 130.61, 136.47 and 4.34%, respectively. The results indicated that light, air condition, and vitamin C were significantly important to the chemical quality of green tea during storage.

• Journal of ILASS-Korea
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• v.9 no.4
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• pp.17-23
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• 2004

Spray characteristics of a twin-hole air shrouded nonle designed for gasoline injectors was investigated by using laser diffraction particle analyzer (LDPA) and tomography reconstruction- A confined spray chamber which is optically accessible through a pair of glass windows was made to simulate the fuel injection condition in intake manifold of gasoline engine. The measurement was applied to the twin hole injector with and without an air shroud. It demonstrates that for the case with an air shroud, fine atomization is achieved and there exists a large number of fine droplets between the region of the main spray streams, which conforms with the spray visualization. The drop size distribution was investigated as a function of elapse time after fuel injection. The distribution was greatly affected by the measurement position from the injector exit. Also, the spatially resolved spray volume fraction and Sauter Mean Diameter (SMD) from line-of-sight data of the LDPA are tomographically reconstructed by Convolution Fourier transformation under the steady injection condition.

• Journal of the Korean Society of Safety
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• v.28 no.1
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• pp.52-56
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• 2013

The purpose of this study is to evaluate the influence of form-oil on steam-cured concrete surface condition. Based, viscosity(high, medium, low) and flash point($26^{\circ}C$, $70^{\circ}C$) of form oil were considered as test variables. The digital image process method was applied for the extraction of air-void area from concrete surface. Test result showed that oil-based form oil reduced air-void by approximately 46% compared to water-based form oil, and the higher the viscosity was, the smaller air-void rate was. In addition, it was conformed that flash point of form oil had a considerable influence on the surface condition of steam-cured concrete.