• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11b
• /
• pp.405-412
• /
• 2000

A natural air in-bin grain dryer with a grain circulator was developed for on farm use. Natural air drying test for rough rice was carried out to evaluate drying rate, uniformity of moisture content distribution in grain bed and energy consumption. It took 10 days to dry 8 ton of paddy rice from 21.9%(w.b) to 16.7%(w.b) moisture contents using the prototype dryer. The average drying rate was 0.52%/day. The uniformity of moisture content after drying was superior to the conventional natural air dryer where is grains were not circulated during drying periods. The dryer performance evaluation index was 738.3KJ/(kg.water), which was more effective than that of grain circulation t)pe hot air dryer(3,500-5,000 KJ/kg.water).

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.4
• /
• pp.523-528
• /
• 2013

In recent years, many efforts are increasingly being made to conserve the natural environment with enhanced emission standards and air quality standards. Also there are various methods necessary to be researched to minimize the emission of air pollutants. In particular, boilers of industrial facilities are major portions of the air pollution. The front duct which needs to be designed to reduce the gases to the electrostatic precipitator requires a bent tube, a reduction/extend tube and an auxiliary equipment, that is, a guide vane. This paper proposes an optimum design of the guide vane by a case study for electrostatic precipitator's flow uniformity. The operating conditions of this study are as follows: BMCR (Boiler Maximum Continuous Rate) and MGR (Maximum Guaranteed Rate) are 75%, 50%, and 30%; turbulent fluid dynamics model is based upon K-${\varepsilon}$ formulation. Presentation of the computed motion of particles is found to be quite useful to predict the precipitator performance by use CFD (Computational Fluid Dynamics).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.1 no.4
• /
• pp.276-289
• /
• 1989

The airflow characteristics in both the upper plenum and the clean space of clean room are investigated by measuring the pressure distribution of the upper plenum and the velocity profile in the clean space, at the various conditions of the supplied airflow rate, the volume of upper plenum and the air supply type. The performance of vertical air supply type and horizontal air supply type is analyzed in terms of the airflow uniformity which is frequently used in indicating the clean room performance, and the relations among the volume of upper plenum, the supplied airflow rate and the airflow uniformity are confirmed. The results of this experimental study can be applied to the designing of the upper plenum of clean room.

• 유체기계공업학회:학술대회논문집
• /
• 2005.12a
• /
• pp.796-802
• /
• 2005

Numerical analysis has been conducted for improving air flow characteristics in the exhaust aftertreatment system of diesel-fueled passenger cars by changing axial length and cone shape of a DPF diffuser. The results of air velocity and static pressure distributions along with air flow uniformity results suggest that a diffuser shape with 2D or 3D function type is better for air flow patterns in front of a DPF.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.4
• /
• pp.44-51
• /
• 2005

In this paper, a new polishing head with the variable pressure structure was studied to improve the planarization uniformity of the conventional template-metal head. Metal surface waviness and slurry distribution on the pad have been known to affect the polishing uniformity even in the synchronized quill and platen velocities. A polishing head with silicon rubber sheet was used to get a curved pressure distribution. In the experiment, the vertical deflection behavior on the pad was characterized with back pressure in the air chamber. Quill force increased linearly with backpressure. However, backpressure under a quill force made the upward movements of the quill. In the wafer polishing experiments, polishing rate and polishing thickness distribution were severely changed with backpressure. The best uniformity was observed with the standard deviation off.5％ level of average polishing removal 215nm at backpressure 12.1kPa.

• Journal of the Semiconductor & Display Technology
• /
• v.3 no.3
• /
• pp.41-44
• /
• 2004

The aim of this study is the confirmation of the coating uniformity affected by the surface tension and wall attachment angle in a slit-coater model. In this work, we use the commercial code (Fluent) to solve the two-phase flow formed with air and photo resist numerically. The results show that the surface tension is the most important factor to determine the coating efficiency in the view of coating uniformity, and the coating uniformity is 2% for our slit-coater model and conditions. To improve the coating uniformity, it is in need of minimization of the sidewall effect of slit-coater.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.1 no.2
• /
• pp.132-139
• /
• 2001

We considered the uniformity of fabricated micromirror arrays by characterizing the fabrication process and calculating the appropriate driving voltages of micromirrors used as virtual photomask in maskless photolithography. The uniformity of the micromirror array in terms of driving voltage and optical characteristics is adversely affected by factors, such as the air gap between the bottom electrode and the mirror plate, the spring shape and the deformation of the mirror plate or torsion spring. The thickness deviation of the photoresist sacrificial layer, the misalignment between mirror plate and bottom electrode, the aluminum deposition condition used to produce the spring and the mirror plate, and initial mirror deflection were identified as key factors. Their importance lies in the fact that they are related to air gap deviations under the mirror plate, asymmetric driving voltages in left and right mirror directions, and the deformation of the Al sring or mirror plate after removal of the sacrificial layer. The plasma ashing conditions used for removing the sacrificial layer also contributed to the deformation of the mirror plate and spring. Driving voltages were calculated for the pixel operation of the micromirror array, and the non-uniform characteristics of fabricated micromirrors were taken into consideration to improve driving performance reliability.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.566-569
• /
• 2006

The purpose of this study is to develop digital air meter used pressure sensor for measurement of air content in freshly mixed concrete by pressure method. The digital air meter can enhanced measurement accuracy and uniformity of air content in freshly concretes, according to use of pressure sensor and measuring process automation. Finally, the digital air meter in this study is improved reproducibility and reliability of measurement compared with analog air meter.

• Journal of Bio-Environment Control
• /
• v.30 no.4
• /
• pp.383-392
• /
• 2021

It has been known that oyster mushrooms cultivated in facilities with thermal insulation have been strongly affected by inner environments. Forced air-circulation fans exert much direct influence on disturbing air inside the facility so the matter is of particular interest. This study is carried out to investigate the measured levels of air uniformity in a cultivation facility for oyster mushroom in the various cases that reversibly controlled air-circulation fans which drove the flow in the upward and reverse direction by turn and unidirectional fans by which the wind blew upwards only were operated from July 1 to 10. The actual survey for the selection of ongoing operation cases presented that farmers, even though there were some discrepancies, have made use of fans in a way that it paused for 5-30min after running for 5-15min by turn. The level of air uniformity in the case of adopting reversible fans revealed a slight difference of 1.4-1.8℃ (Temp.) and 7.8-8.7% (R.H.) under the condition of not using a cooler during the investigation period. By contrast, unidirectional fans showed a noticeable difference of 3.2-3.7℃ and 14.0-15.4%, which meant that air uniformity driven by reversible fans much more increased compared to that for unidirectional fans. Among the twenty operational applications considered for reversible fans, the circumstance that the wind blew upwards for 10-15min and ceased for 5-10min and blew again in the reverse direction for 10-15min in succession gave minor improvements at the level of air uniformity, but at present there was somewhat difficult to make decision on which cases were optimally best. It seems necessary that the effects of reversible fans on air uniformity as well as qualities of oyster mushrooms have to be appraised in the cultivation period and the flow visualization needs to be done to ascertain the performance of air mixture.

• Journal of Biosystems Engineering
• /
• v.25 no.3
• /
• pp.227-232
• /
• 2000

A natural air in-bin grain dryer with a grain circulator was developed for on farm use. Natural air drying test for rough rice was carried out to evaluate drying rate, uniformity of moisture content distribution in grain bed and energy consumption. It took 10 days to dry 8 ton of paddy rice from 21.9%(w.b) of moisture contents to 16.7%(w.b), by prototype dryer and the average drying rate was 0.52%/day. The uniformity of moisture content after drying was superior to a conventional natural air dryer in which grains were not mixed during drying periods. The dryer performance evaluation index was 738.3kJ/(kg.water), which was more effective than that of grain circulation type hot air dryer(3,500∼5,000 kJ/kg.water)