• Korean Journal of Agricultural Science
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• v.40 no.4
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• pp.317-323
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• 2013

This research was conducted to obtain the basic information for establishment of standard guidelines in the design and installation of roof ventilation system in single-span plastic greenhouse. To achieve this, the greenhouse structure & characteristics, cultivation status, and ventilation system were investigated for single-span greenhouse with roof ventilation system cultivating the Cucurbitaceae vegetables, watermelon, cucumber, and oriental melon. Most of single-span watermelon greenhouse in Haman and Buyeo area were a hoop-style and the ventilation system in those greenhouses mostly consisted of two different types of 'roof vent (circular or chimney type) + side vent (hole) + fan' and 'roof vent (circular type) + side vent (hole or roll-up type)'. The diameter of circular and chimney-type vent was mostly 60cm and the average number of vents was 10.5 per a bay with vent spacing of average 6.75m. The ratio of roof vent area to floor area and side vent area in the single-span watermelon greenhouse with ventilation fan were 0.46% and 7.6%, respectively. The single-span cucumber greenhouse in Haman and Changnyeong area were a gable roof type, such as even span, half span, three quarter and the 70.6% of total investigated single-span greenhouses was equipped with a roof ventilation fan while 58.8% had a circulation fan inside the greenhouse. The ratios of roof vent area to floor area in the single-span cucumber greenhouse ranged from 0.61 to 0.96% and in the case of the square roof vent, were higher than that of the circular type vent. On average, the roof ventilation fan in single-span cucumber greenhouse was equipped with the power input of 210W and maximum air volume of $85.0m^3/min$, and the number of fans was 9.75 per a bay. The number of roof vent of single-span oriental melon greenhouse with only roll-up type side vent ranged from 8 to 21 (average 14.8), which was higher than that of other Cucurbitaceae vegetables while the vent number of the greenhouse with a roof ventilation fan was average 7 per a bay.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.136-141
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• 2012

Performance improvement of local exhaust system used in toilet and cooking place are main concern in a field of ventilation. In Korea, There are many high riser residential apartments in recent years. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depends on stack effect. This study investigates on the performance improvement of terminal device, roof fan, of vertical spiral duct used in high riser residential apartments. This paper focuses mainly on the effect of accessories, number or shape of blades, composed of roof fan with function of exhaust air volume of toilet and cooking place. Roof fan with 10 blades is observed at optimum exhaust performance in this study.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.2
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• pp.139-146
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• 2011

The ventilation performance of a vertical exhaust duct system in the high riser public house has been evaluated by a commercial software, Fluid Flow, which solves pressure losses through the duct system including bathroom fans and a hybrid roof fan. During the numerical simulations, outdoor wind condition and stack effects in summer and winter were considered as well as the operating conditions of a basement damper and the roof fan. The results show that the bathroom ventilation in summer is the most unsatisfactory. The opening of the basement damper has a problem that the polluted air in the lower floors is exhausted to the underground parking lot, not to the rooftop. If the basement damper is closed, the exhaust flow rate in the lower floors is not sufficient due to the strong flow resistance in the long vertical duct even though the roof fan is under operating.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.889-894
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• 2008

Exhaust system used in toilet and cooking place of high riser public house is roof fan of two basic types : natural roof ventilator and natural/forced roof ventilator. Natural/forced roof ventilator has a motor in the rotary shaft. There are many high riser public house in Korea. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depend on stack effect. This study investigates on stack pressure determined by exterior pressure and the difference pressure control in exhaust stack used in high riser public house. This paper focuses mainly on the effect of the time interval for power supply of motor installed in roof fan with function of natural wind velocity and of exhaust air volume of toilet. It is observed there are higher exhaust efficiency than the existing natural roof ventilator.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.334-342
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• 2016

In order to evaluate the modified installation methods of roof ventilation devices, derived from the previous experiment ('investigation into the optimum capacity of roof ventilation devices and their deployment'), the conventional and modified (improved) roof ventilation systems were installed in the single-span plastic greenhouse for growing oriental melons. The roof vents ($60{\varphi}$) and roof fans (maximum air capacity of $38m^3/min$) were installed in the spacing of 15m (FT, modified 'side vent+roof fan' ventilation) and 6m (TT, modified 'side vent+roof vent' ventilation) respectively on the roof of greenhouses for the modified roof ventilation treatments, and 20m (FC, conventional 'side vent+roof fan' ventilation) and 8m (TC, conventional 'side vent+roof vent' ventilation) for the conventional ones. The stem diameter, leaf blade lengh, petiole length, and leaf width were lower in the FT and TT treatments than those in the conventional treatments, FC and TC. Although the fruit weight and total yields were slightly lower in the FT and TT treatments, the marketable fruit ratio (%) were higher, as a result of increased fruiting ratio (%) in these treatments, than those of FC and TC. The marketable yields (kg/10a) in the FT and TT treatments were 8,391 kg/10a and 7,283 kg/10a, which were respectively 661 kg/10a and 487 kg/10a higher than those in the treatments of FC and TC. The modified installation methods of roof fan resulted in production of more female flowers and lower fruit drop ratio (%) compared to conventional meathods. In the treatment of the conventional ventilation with roof vent, the fruit weight, fruit length & width, and flesh thickness were higher than in other treatments, but there were no significant differences in the fruit width and flesh thickness among the treatments.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.3
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• pp.60-67
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• 2014

Exhaust system used in toilet and cooking place of high riser public house is roof fan of two basic types : natural roof ventilator and natural/forced roof ventilator. Natural/forced roof ventilator has a motor in the rotary shaft. There are many high riser public house in Korea. These buildings were not viewed as being major contributors to exhaust pollutants producted in indoor. It was because many engineers thought that exhaust in high riser building depend on stack effect. This study investigates on stack pressure determined by exterior pressure and the difference pressure control in exhaust stack used in high riser public house. This paper focuses mainly on the effect of the time interval for power supply of motor installed in roof fan with function of natural wind velocity and of exhaust air volume of toilet. It is observed there are higher exhaust efficiency than the existing natural roof ventilator.

• Wind and Structures
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• v.19 no.1
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• pp.15-33
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• 2014

This paper describes partial turbulence simulation and validation of the aerodynamic pressures on building models for an open-jet small-scale 12-Fan Wall of Wind (WOW) facility against their counterparts in a boundary-layer wind tunnel. The wind characteristics pertained to the Atmospheric Boundary Layer (ABL) mean wind speed profile and turbulent fluctuations simulated in the facility. Both in the wind tunnel and the small-scale 12-Fan WOW these wind characteristics were produced by using spires and roughness elements. It is emphasized in the paper that proper spectral density parameterization is required to simulate turbulent fluctuations correctly. Partial turbulence considering only high frequency part of the turbulent fluctuations spectrum was simulated in the small-scale 12-Fan WOW. For the validation of aerodynamic pressures a series of tests were conducted in both wind tunnel and the small-scale 12-fan WOW facilities on low-rise buildings including two gable roof and two hip roof buildings with two different slopes. Testing was performed to investigate the mean and peak pressure coefficients at various locations on the roofs including near the corners, edges, ridge and hip lines. The pressure coefficients comparisons showed that open-jet testing facility flows with partial simulations of ABL spectrum are capable of inducing pressures on low-rise buildings that reasonably agree with their boundary-layer wind tunnel counterparts.

• Korean Journal of Agricultural Science
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• v.42 no.4
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• pp.325-333
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• 2015

The ventilation systems composed three types of side vent (roll-up) 'SV', side vent+roof vent 'SV+RV', and side vent+roof fan 'SV+RF' with 7.5 m spacing, with specific set point temperatures for ventilation: SV ($35^{\circ}C$ open / $33^{\circ}C$ close), SV+RV or SV+RH ($35^{\circ}C$ open/$33^{\circ}C$ close for root ventilation and $37^{\circ}C$ open / $35^{\circ}C$ close for side vent). In the treatment of SV+RV, although the average daily maximum temperature inside the greenhouse temporarily increased by $38-40^{\circ}C$, thermal stress by high temperature did not occur and the disease incidence (%) of powdery mildew and downy mildew on the oriental melon were 25 - 75% lower than in the conventional SV treatment. In the SV treatment, the disease incidence (%) of powdery mildew and downy mildew were 1.4 - 7.7% and 4.2 - 15.9% for 'Deabakkul', and 20.3 - 22.8% and 2.8 - 11.3%, for 'Ildeungkkul'. The yield for one month was higher in the treatment of SV+RV than those in other treatments, with values of 2,105 kg/10a for 'Deabakkul' and 2,537 kg/10a for 'Ildeungkkul'. The simultaneous treatment with side vent and roof vent resulted in 16.2% higher yield (18.1% higher marketable yield) than that in the SV treatment for 'Deabakkul'.

• Journal of architectural history
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• v.21 no.2
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• pp.21-36
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• 2012

As wooden construction developed, it was observed that the rafters with corners changed to angled rafters. The change from rafters to angle rafters means that the angle rafters became the most important member in supporting the roof weight as the construction scale increased and structurally developed. The specific installation methods of angle rafters were all unique in Korea, China, and Japan. In East Asia, the angle of the angle rafter gradually decreased along with the development of construction. However, in Joseon Dynasty Korea, the angle of the angle rafter was larger than that of the Gorye era because the method of fixing the corner of the roof more firmly by building the fan-shaped rafter was utilized. The changes to the angle rafter installation method is a unique characteristic of Korea, in that it was developed in a totally different way from the methods used in China and Japan.

• Journal of Animal Environmental Science
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• v.4 no.1
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• pp.1-8
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• 1998

The objective of this study was conducted to develope a mobile pig nursery(MPN) for segregation of early weaned piglet. The units of MPN was consisted of 4 rectangle-type pens, 1 workroom, 2 doors, 3 windows, 1 air-inlet, 1 exhaust fan, and 1 cooling and heating system. Total of 40 piglet were weaned at 7 days of age. The period of the feeding test was 63 days. The results obtained are as follows: 1. The insulation thickness was 70, 70 and 50 mm of roof, floor and wall, respectively. R-value was 15.32 and 10.32 of roof and wall, respectively. 2. Exhaust fan( 30.48) was installed near back door 40cm from the bottom. When exhaust fan speeds were 15, 20, 30 and 35%, Air ventilation was required 9.75, 7.07, 1.72, 1.45 minutes of respectively. 3. Average temperature in the MPN was able to maintain 27∼28$^{\circ}C$ from 7∼28 days of age, 24∼25$^{\circ}C$ from 35∼56 days of age and 20∼21.5$^{\circ}C$ from 56∼70 days of age. 4. Average daily gain, feed intake and feed conversion were 420.6g, 761.5g, 1.81 respectively.