• Tuberculosis and Respiratory Diseases
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• 제79권4호
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• pp.234-240
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• 2016

Transmission of tuberculosis (TB) is a recognized risk to patients and healthcare workers in healthcare settings. The literature review suggests that implementation of combination control measures reduces the risk of TB transmission. Guidelines suggest a three-level hierarchy of controls including administrative, environmental, and respiratory protection. Among environmental controls, installation of ventilation systems is a priority because ventilation reduces the number of infectious particles in the air. Natural ventilation is cost-effective but depends on climatic conditions. Supplemented intervention such as air-cleaning methods including high efficiency particulate air filtration and ultraviolet germicidal irradiation should be considered in areas where adequate ventilation is difficult to achieve. Personal protective equipment including particulate respirators provides additional benefit when administrative and environmental controls cannot assure protection.

• 설비공학논문집
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• 제4권4호
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• pp.253-262
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• 1992

A numerical procedure is introduced to calculate local ventilation effectiveness using the definitions of local decay rate and local mean age. A low Reynolds number $k-{\varepsilon}$ model is implemented to calculate steady state turbulent velocity distributions, and a step-down method is used to calculate transient concentration distributions. Simulations are carried out for several different values of air change rates and several different diffuser angles in a two-dimensional model of a half scale office room. The results show that the local ventilation effectiveness within a room could vary significantly from one location to another. The nominal air change rate based on the assumption of complete mixing of room air does not provide the local ventilation effectiveness information. It is numerically proved that the local mean age distribution obtained from the transient calculation is equivalent to the steady state concentration distribution with homogeneously distributed contaminant sources.

• 한국농공학회논문집
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• 제54권2호
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• pp.55-65
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• 2012

In the winter season, when the ventilation system is operating, the fresh cold air from the slot-type openings of broiler house which directly reached the animal zone can cause various problems such as thermal stress, decreasing of feed and water consumption, occurrence of respiratory disease, and etc. Therefore it is very important to control the trajectory of aero-flow from the slot openings to induce an efficient thermal heat change. Jet-drop distance model was proposed to predict and control the jet-trajectory. However their study was restricted due to the small scaled model and difficulties of measuring the Jet-drop distance. In this study, CFD was applied to analyze qualitatively and quantitatively the jet-drop distance in a real broiler house. The various variables were considered such as installed slot-angle, designed ventilation rate, and the outdoor ambient temperature. From the present study, two linear-regression models using the Jet-drop factor and corrected Archimedes number, and their R-squared values 0.744 and 0.736, respectively, were used. From this study, the applicability of CFD on the analysis of Jet-drop distance model was confirmed.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1392-1397
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• 2008

This study is to measure the change of the $CO_2$ and floating dust concentration depending on the volume of the ventilation and the state of on/off the ventilation for the estimation of the air pollution in classroom. The results could be summarized as follows: the test cell was the two full scaled model and the one is set up with ventilation system another was not. the volume of classroom is 170.1m3 and the number of persons are 35. 1)when the ventilation system was not installed, The experimental results of the $CO_2$ concentration showed the average of 2,150ppm and the maximum of 2,740ppm in the classroom. This was the higher than 1,000ppm, the standard value of ASHRAE and the enforcement regulations of School Sanitation Code in Ministry of Education & Human Resources Development, 1000ppm. The $CO_2$ concentration was relatively increasing during school hours. 3)In case of the volume of ventilation of $800m^3$/h, the $CO_2$ concentration of classroom showed the average of 962 ppm and the maximum of 1,380 ppm. This was higher than 1,000ppm, the standard of ASHRAE and the enforcement regulations of School Sanitation Code in Ministry of Education & Human Resources Development. 4)The floating dust(PM10) was the maximum of 0.52 mg/$m^3$, the minimum of 0.25 mg/$m^3$, and the average of 0.32 mg/$m^3$ in case of the ventilation system off. Those were higher than the standard value 0.15 mg/$m^3$. In case of the ventilation system on, the floating dust(PM10) was the maximum of 0.174 mg/$m^3$ , the minimum of 0.048 mg/$m^3$, and the average of 0.078 mg/$m^3$. These were the lower than 0.15 mg/$m^3$, the standard of the enforcement regulations of School Sanitation Code in Ministry of Education & Human Resources Development. 5)The concentrations of $CO_2$ and PM10 were largely depending on the number of students and the ventilation system, The installation of the ventilation system is necessary for the amenity environment and the management of the indoor air quality.

• 원예과학기술지
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• 제34권6호
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• pp.845-859
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• 2016

본 연구는 스탠다드 국화 '백마'의 시설재배에 있어서 야간 환기 방법과 난방처리 조건에 따른 온습도의 변화, 흰녹병 발생 및 절화의 생육에 미치는지 영향을 알아보고자 수행되었다. 환기 방법에 관한 실험에서 측창을 밀폐시킨 대조구의 평균 상대습도 94.5%에 비해 자연환기는 74.3%, 자연+Fan환기 처리구에서는 72.8%로 낮았다. 흰녹병 발생률은 대조구 100%, Fan환기 98.3%, 자연환기 75.6%, 자연+Fan환기 처리구에서 43.4%로 나타났다. 또한 발병엽수와 동포자퇴수도 다른 처리들보다 자연+Fan환기 처리는 가장 적었다. 대조구에서는 과습과 흰녹병 발생으로 절화의 생육이 크게 억제되었는데, 자연+Fan환기 처리구는 초장, 엽수, 줄기직경, 절화의 생체중 등 절화의 생육이 양호하였다. 난방 조건에 따른 시설 내의 야간 평균 온도는 대조구인 RH 95% 난방처리에서 $18.4^{\circ}C$ 인데 반하여 RH 70% 난방처리에서 $25.8^{\circ}C$ 로 나타나 $7.4^{\circ}C$ 상승하였다. RH 70% 난방처리에서도 흰녹병 발생률 34.4%, 주당 발병엽수 0.9개, 발병엽당 동포자퇴수 1.0개로 대조구보다 흰녹병 발생이 크게 억제되었다. 또한 RH 70% 난방 처리구에서 습도가 높은 대조구보다 초장, 엽수, 줄기직경, 생체중 등 절화의 생육이 양호하였다. 따라서 시설 내에서 국화 '백마'를 재배시 자연+Fan환기와 난방처리는 흰녹병을 크게 억제할 수 있을 뿐만 아니라 절화의 생육에도 효과적이었다.

• 대한조선학회논문집
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• 제52권3호
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• pp.206-221
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• 2015

Supercavitation is a modern technique which can be used to surround an underwater vehicle with a bubble in order to reduce the resistance of the vehicle. When the vehicle is at low speed in the deep sea, the cavitation number is relatively big and it is difficult to generate a cavity large enough to envelope the vehicle. In this condition, the artificial cavity, called ventilated cavity, can be used to solve this problem by supplying gas into the cavity and can maintain supercavitating condition. In this paper, a relationship between the ventilation gas supply rate and the cavity shape is determined. Based on the relationship a ventilation rate control is developed to maintain the supercavitating state. The performance of the ventilation control is verified with a depth change control. In addition, dynamics modeling for the supercavitating vehicle is performed by defining forces and moments acting on the vehicle body in contact with water. Simulation results show that the ventilation control can maintain the supercavity of an underwater vehicle at low speed in the deep sea.

• 한국입자에어로졸학회지
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• 제9권2호
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• pp.59-67
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• 2013

One of purposes in this study was to confirm the behavior of coughed particles under different ventilation conditions. Three types of ventilation systems were applied for this experiment and the properties of coughed particles were measured using computational fluid dynamics (CFD) in an intensive care unit. The changes of total airborne particles for each case showed different trends according to the ventilation type and time, but the deposited particles were similar in all conditions. Although the time taken for 50% of the particles to be deposited was the fastest in case 2, the portion of deposited particles after 300 seconds was only 5% in all conditions. In case 1, a relatively small number of particles were deposited on the wall, but the particle exhaust and deposition on the occupants were the highest. In case 3, the downward ventilation was applied as that recommended by the US Center for Disease Control and Prevention (CDC) and showed different exhaust efficiencies according to the particle size.

• 한국응급구조학회지
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• 제9권2호
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• pp.55-78
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• 2005

The purpose of this study was to provide basic data for the improvement of the guidelines and training programs regarding the cardiopulmonary resuscitation performance of bystanders who can respond to the incidents in earlier times as the first responder of the cardiac arrest incident, by reviewing the performance of basic CPR and the influencing factors after providing 70 students of Department of Emergency Medical Technology with the CPR training. For the purpose of the study, the collected data were computerized and analyzed by SPSS-WIN program(ver. 10.1). The results for this study were as follows The duration of session between the groups in the BLS CPR were 3 minutes and 36 seconds, 2 minutes and 32 seconds respectively. The average compression number per minute were 24.3 times and 33,2 times respectively(p=.000), and the average compression rate per minute were 112 times and 122 times respectively(p=.000). The average ventilation number per minute were 3.54 times and 5.1 times respectively(p=.000). The errors in compression "Too shallow" were 20.73 times(34.6%) and 23,23 times(38,7%) out of 60 times in 4 cycles with the standard of 38 nun. In CPR performance results according to gender in the first episode, males showed better results in compression depth as 41.5 mm comparing to females average 38.2 mm(p=.015). When ventilation results were compared according to the use of FS, the average ventilation number per minute, total ventilation per minute and the average volume per episode were significantly higher when FS was not used(<.040), There was no significant difference in ventilation accuracy between two groups. According to the results, we need to improve and distribute portable barrier devices, and to be familiar with those devices. We need to enforce ventilations as well as to include compressions so that faster and more accurate CPR can be performed. Additionally, we need to exclude ventilation only cases, minimize the interference time of chest compression due to inaccurate ventilation, simplify or minimize the complicatedness of CPR performance and responding time related to breathing, provide first responders with various training programs such as initial assessment and ventilations only, or initial assessment and chest compression-only CPR and than provide advanced training with AHA BLS education including CPR for more than two people according to CPR skills and target characteristics.

• Journal of Mechanical Science and Technology
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• 제19권4호
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• pp.1001-1005
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• 2005

This paper evaluates the performance of ventilation for the removal of indoor pollutants as a function of ventilation rate and the number of occupants in a test room and school classroom. An experimental apparatus consists of a test room, a tracer gas supply system, a gas detector, and a fan for ventilation air supply with a controller. The ventilation performance is evaluated in a step-down method based on ASTM Standard E741-83 using $CO_{2}$ gas as a tracer gas in the test room of 35 $m^{3}.$ For the ventilation air flow rate of 1.0 ACH, a recommended ventilation flow rate of Korea school standard for acceptable indoor air quality in the case of one person, CO_{2}$ gas concentration decreases up to $55{\%}$ within 50 minutes without occupancy and increases up to $75{\%}$ in the case of one occupant. Also indoor air quality at the school classroom is investigated experimentally.

• Asian-Australasian Journal of Animal Sciences
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• 제12권8호
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• pp.1310-1315
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• 1999

Air quality in confinement pig houses is important to production and health. Mechanical ventilation and confinement is known to be the most practical tool for maintaining adequate air quality in pig houses through extensive researches since Millier (1950) invented the 'slotted inlet' ventilation system. A variety of mechanical ventilation systems have been applied to confined nursery pig houses in Korea without scientific verification of their ventilation effectiveness. Ventilation systems with three feasible combinations (NA, NB, and NC) of inlets and outlets in a confined nursery pig house were tested to evaluate their ventilation efficiency, of which the one with the performance was supposed to be taken as a standard ventilation system for nursery pig houses in Korea. Field data of air velocity and temperature fields, and ammonia concentration with three ventilation systems were taken and compared to determine the best system. The air velocity and temperature fields predicted by the PHOENICS computer program were also validated against the available experimental data to investigate the feasibility of computer simulation of air and temperature distribution with an acceptable accuracy in a confined house. NC system with duct-induced in-coming air, performed best among the three different ventilation systems, which created higher velocity field and evener distribution ($2.5m/s{\pm}0.3m/s$) over the space with a Reynolds number of $10^4$. The experimental data obtained also fitted well with the simulated values using the modified PHOENICS, which suggested a viable tool for the prediction of air and temperature field with given calculation geometries.