• KOREAN POULTRY JOURNAL
• /
• v.36 no.7 s.417
• /
• pp.70-74
• /
• 2004

최근 육종개량의 발전과 성과로 인하여 대형화되었지만 고밀도 사육에 의해서 하절기 열사병과 심한 더위로 인한 생산성 저하가 큰 문제로 혹서기에 대두되고 있어 그 대응책을 반드시 세워야 할 것이다. 하절기 온도관리 대책으로서는 계사내의 공기유통을 좋게 하는 것이 가장 기본이므로 충분한 환기에 의해 닭의 체감온도를 낮추어 주게 되는 것이다. 그러나 우리나라와 같이 여름철의 기후 특성이 고온다습한 경우는 습도가 높아지게 되면 체감온도는 낮아지지 않는다. 그러므로 계사내의 습도를 저하시키기 위해서 환기휀 등을 이용해 깔짚과 계분을 건조시키는 것도 한가지방법이다. 일반적으로 열사병 대책으로 실시하고 있는 방법으로서는 입기구에 물 분무, 지붕에 물 분무, 계사내의 미세한 분무냉각 등 물을 이용하는 방법이나, 환풍기의 설치, 닥트송풍을 이용한 방법, 거칠고 얇은 그물에 의한 차광 등의 방법으로 온도를 낮게 할 수가 있다. 특히 산란계의 경우 여러 연구보고 자료에 의하면 산란계를 고온 환경에서 사육할 경우 난각질이 저하된다고 하는 보고가 많이 있다. 1일 중에 환경온도를 주기적으로 변화시킨 경우는 일정하게만 유지해 주는 환경온도에 비해서 난각질과 난각강도는 낮아지게 된다. 또한 산란계에 있어서 간헐점등에 대해서는 에너지 수준을 줄이는 기술, 또는 사료절감을 유도하는 방법은 계속 연구되고 있다. 따라서 다음은 하절기 산란$\cdot$육계사의 적온유지를 위한 온도관리 사례에 대하여 이야기하고자 한다.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.7 no.1
• /
• pp.13-25
• /
• 2005

In general, tunnel ventilation is analyzed with the assumption of equal vehicular speed for both directions in bidirectional traffic tunnels. This practice is likely to result in minimizing the piston effects and cannot take into consideration the effects of real situations, since in most cases, speeds of vehicles moving in opposite directions are not equal. Therefore, The ultimate goal of this study is to review the effects of unequal vehicular speeds on the planning of local bidirectional tunnel ventilation. To apply unequal vehicular speed for the bidirectional tunnel ventilation plan, the following requirements are necessary; (1) Adoption of strict smoke concentration standards for 'free-flow & congested' traffic conditions, (2) Selection of an appropriate ratio of heavy directional traffic volume, and (3) Selection of reasonable stepwised magnitude of speed difference. Based on the importance of research topic, this study aims at comparing the differences of the capacity of ventilation equipment for the cases with equal and unequal vehicular speeds in local bidirectional tunnels.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.3
• /
• pp.409-420
• /
• 2017

The amount of ventilation required in making the tunnel ventilation plan is an important factor for determining the capacity of the ventilation system. The amount of pollutant emission for each type of vehicle (basic emission amount for the design of ventilation volume) for estimating the required ventilation amount is based on the 'Standard for Allowing the Emission for the car manufacturing', proposed by Ministry of Environment. However, in 2013, the Ministry of Environment announced the 'Regulations on the calculation method of total emissions from vehicles' as a regulation for calculating the pollutants emitted from vehicles. In this regulation, there are the 'Emission factors for each type of vehicle'. Therefore, it is necessary to review the application of the Regulation to the estimation of the required ventilation volume for the road tunnel. In this study, the influence of the strengthened emission regulation in 2015 caused by the case of manipulation of emission volume for the diesel vehicle on the calculation of the required ventilation volume in the road tunnel has been checked. In addition, in this study, the required ventilation volume calculated according to the Standard for Allowing the Emission for the car manufacturing revised by Ministry of Environment and "Emission factors for each type of vehicle" and that calculated according to the EURO emission standard were compared for analysis. This study has implications that it provides the basic design data for calculating the reasonable ventilation capacity of the ventilation system based on the ground for calculating the required ventilation volume.

• Journal of Bio-Environment Control
• /
• v.22 no.1
• /
• pp.7-12
• /
• 2013

Environmental measurements in the many different types of horticultural farms were carried out to evaluate the ventilation performance for multi-span plastic greenhouses according to the eaves height, the number of spans, the existence of side wall vents and the position of roof vents. Hydroponic tomatoes were being cultivated in all experimental greenhouses, and ventilation rates of the greenhouses were analyzed by the heat balance method. It showed that the ventilation rate in the greenhouse with 4 m eaves height increased about 22% compared to the greenhouse with 2 m eaves height. The ventilation rate in the greenhouse with 9 spans decreased about 17% compared to the greenhouse with 5 spans. In the greenhouse with 9 spans, if there were no side wall vents, the ventilation rate showed about a third of the case that side wall vents were open. Overall, as the eaves height was higher and the number of spans was smaller in multi-span greenhouses, the natural ventilation performance was better. And the ventilation performance was best in the greenhouse which the eaves height was high and the position of roof vents was ridge, not gutter. Therefore, in order to maximize the natural ventilation performance, multi-span plastic greenhouses need to improve their structures such as that make the eaves height higher, place the roof vents on the ridge, install the side wall vents as much as possible, and the number of spans is limited to about 10 spans.

• Journal of Bio-Environment Control
• /
• v.32 no.3
• /
• pp.197-204
• /
• 2023

Heat stress causes a decrease in immunity and disease occurrence in livestock, increasing mortality and impairing productivity. In particular, chickens are very vulnerable to high temperatures compared to other livestock species because their entire body is covered with feathers and sweat glands are not developed. Currently, air conditioning systems are essential in broiler houses to prevent high-air temperature damage to broilers, but conventional cooling facilities are greatly affected by the external environment, so there are limits to their use. In this study, to propose a cooling method, thermal insulation paint and a heat pump were apply in the broiler houses to evaluate the temperature reduction effect. The heat pump experiment was to analyze the cooling effect according to the change in ventilation rate and propose an appropriate. As a result of the experiment, the heat-insulating paint reduced the temperature of the broiler houses by maximum 1-2℃, and in the broiler houses where the heat pump was operated, the temperature decrease was the largest when the ventilation rate was the lowest. When the air temperature in the house is similar to or lower than the outside air temperature, it is considered to be most effective to use a heat pump while maintaining only the minimum ventilation rate.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.7
• /
• pp.4047-4051
• /
• 2014

Modern apartment houses are constructed to be relatively airtight with a high heat insulation system to increase the energy efficiency. Such a system has a range of deleterious effects due to the insufficient ventilation. In this study, the ondol system, which is used as a heat source typical of winter in Korea, was set as the default system to evaluate the indoor heat environment according to the ventilation method, the factors of energy reduction by the ventilation system was analyzed. The experimental apparatus was used to simulate the ambient conditions for a certain constant temperature and humidity chamber. The experimental results showed that the supply water temperature higher air volume decreases with increasing supply air temperature in the following order: floor supply/exhaust > total heat exchange supply/exhaust > forced supply/exhaust. Through this study, the applicability of various ventilations could be examined.

• Journal of the Korean Society of Radiology
• /
• v.13 no.4
• /
• pp.667-674
• /
• 2019

Because examination with technegas produces images through simple diffusion accumulation, the examination room can become contaminated after scan. Therefore, radiation workers and patients awaiting examination will be affected by internal exposure from technegas inhalation. Before and after gravity ventilation, I am trying to find a way to reduce the exposure dose of waiting patients according to a comparative analysis of horizontal spatial dose rates over time. Spatial dose ratio were measured for 10 minutes from various distances and angles around ventilator's location before and after gravity ventilation. Then, mean values, standard deviation and reduction ratio were calculated. The highest reduction rate of gravity ventilation was 95.31% and the highest reduction ratio was 1 to 3 minutes. Therefore, the gravity ventilation could reduce the exposure dose of radiologic technologists, waiting patients, patient guardians and nurses. In conclusion, the reduction of the exposure dose during the technegas ventilation study through gravity ventilation will play a role in optimiging the protection and it is in accordance with the recommended reduction of the medical exposure by ICRP 103.

• Proceedings of the Acoustical Society of Korea Conference
• /
• autumn
• /
• pp.325-328
• /
• 2000

초음파 변환기의 정합을 위해서는 초음파 변환기의 등가회로 구성이 중요하다. 전통적인 등가회로의 경우 비교적 안정적인 등가회로를 예측하게 해 주지만 초음파변환기 구성에서 일어나는 초음파 변환기 외의 구성품 즉 Backing Material, Acoustic Window Material, Radiation Impedance 등에 의한 부가적인 효과를 모델링하는 데는 한계가 있다. 따라서 좀 더 일반적인 방법으로 초음파 변환기를 모델링하는 방법이 필요하다. 그런 방법의 하나로 주파수 영역 측정에 의한 초음파변환기 등가회로 추정법을 제안한다. 이 방법은 초음파 변환기 제작 시 많이 쓰는 임피던스 분석의 결과를 그대로 사용할 수 있고 또 그것이 없어도 일반 함수발생기와 오실로스코프만으로 측정할 수 있어서 랜덤함수를 발생시키고 이에 대한 출력을 저장해야 데이터를 얻을 수 있는 시간영역 추정법에 대해서 장점을 갖는다.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.14 no.4
• /
• pp.375-395
• /
• 2012

According to the local highway tunnel ventilation guideline, ventilation capacity calculation should be performed at the speed ranging from 10 km/h to 80 km/h. This is so reasonable method considering uncongested and congested traffic conditions in urban tunnels. But recently due to low traffic volume and very low congestion frequency in rural highway tunnels, it seems to be an inadequate way to apply the guideline. Therefore the calculation should be performed separately for the free flow and congested traffic cases classified by the appropriate decision model. This paper aims at determining unnecessary running speed range for reasonable tunnel ventilation design, considering free flow and congested traffic conditions. Firstly, traffic volumes in highway tunnels were collected and if any, the causes of congestion were investigated. And with concept of 'margin speed'($u-u_m$), the decision model on traffic congestion was developed. Applicability of the decision model was also analyzed with case study. According to the results, when design speed is 100 km/h, with V/C less than 0.1, then the range of unnecessary speed in tunnel ventilation design is less than 40 km/h; for $V/C{\leqq}0.35$, $V/C{\leqq}0.6$ and $V/C{\leqq}0.75$, the unnecessary speed ranges are found to be ${\leqq}30$, ${\leqq}20$ and ${\leqq}10km/h$, respectively.

• Horticultural Science & Technology
• /
• v.34 no.6
• /
• pp.845-859
• /
• 2016

This study was conducted to examine the effect of nighttime ventilation and heating on changes in temperature and humidity, the occurrence of white rust, and growth of standard chrysanthemum (Dendranthema grandiflorum) 'Baekma' in a greenhouse. For the ventilation treatments, the mean nighttime humidity in the control greenhouse, which had a closed side window, was higher (94.5%), but the humidity in the natural and natural+fan ventilation treatments was lower (74.3% and 72.8%, respectively). The rate of occurrence of white rust at 34 days after treatment was 100, 98.3, 75.6, and 43.3% for the control, fan ventilation, natural ventilation, and natural+fan ventilation treatments, respectively. The number of infected leaves and telia were the lowest in the natural+fan ventilation treatment compared with the other treatments. The growth of the chrysanthemum 'Baekma' was significantly suppressed in the control because of the occurrence of white rust and high humidity, while plant height, number of leaves, stem diameter, and fresh weight were the greatest in the natural+fan ventilation treatment. For the heating treatments, the mean nighttime temperature of the control (RH 95% heating), which was heating and held at 95% humidity, was $18.4^{\circ}C$, while the temperature of the heating treatment, which was held at 70% relative humidity (RH 70% heating) was $25.8^{\circ}C$. The rate of occurrence of white rust (34.4%), number of infected leaves (0.9), and telia (1.0) were the lowest in the RH 70% heating treatment compared with the other heating conditions. Also, the RH 70% heating treatment showed the best growth in terms of plant height, stem diameter, number of leaves, and fresh weight. Therefore, the natural+fan ventilation and RH 70% heating treatments were effective for the control of white rust and the growth of standard chrysanthemum 'Baekma' in a greenhouse.