• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.135-148
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• 2005

In the stage of conceptual design for the construction and operation of the geologic repository for radioactive wastes, it is important to consider a repository ventilation system which serves the repository working environment, hygiene & safety of the public at large, and will allow safe maintenance like moisture content elimination in repository for the duration of the repositories life, construction/operation/closure, also allowing safe waste transportation and emplacement. This paper describes the possible ventilation system design criteria and requirements for the prospective Korean radioactive waste repositories with emphasis on the underground rock cavity disposal method in the both cases of low & medium-level and high-level wastes. It was found that the most important concept is separate ventilation systems for the construction (development) and waste emplacement (storage) activities. In addition, ventilation network system modeling, natural ventilation, ventilation monitoring systems & real time ventilation simulation, and fire simulation & emergency system in the repository are briefly discussed.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.1-11
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• 2017

Most of the local limestone mines are developed as large-opening underground mines, while mine ventilation is heavily dependent on the natural ventilation and auxiliary systems, rather than the mechanical ventilation system using main fans. The current auxiliary ventilation system with fan and ducting requires optimization since enhanced deployment of diesel equipment demands higher airflow rate and the associated cost is expected to be too excessive for the local mine operators. This paper aims at optimizing the fan capacity for the working site ventilation through comparing the fan pressure in the mine airway and the ventilation efficiency of an axial-flow fan and a propeller fan developed in this study.

• Journal of Korean Society of Forest Science
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• v.9 no.1
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• pp.1-44
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• 1969

The important results which have been obtained in the investigation can be recapitulated as follows. 1. As demostrated by the experimental results and analyses concerning their effects in the on-ground type mushroom house, the constructions in relation to the side wall and ceiling of the experimental houses showed a sufficient heat insulation on effect to protect insides of the houses from outside climatic conditions. 2. As the effect on the solar type experimental mushroom house which was constructed in a half basement has been shown by the experimental results and analyses, it has been proved to be effective for making use of solar heat. However there were found two problems to be improved for putting solar houses to practical use in the farm mushroom growing: (1) the construction of the roof and ceiling should be the same as for the on-ground type house, and (2) the solar heat generating system should be reconstructed properly. A trial solar heat generating system is shown in Fig. 40. 3. Among several ventilation systems which have been studied in the experiments, the underground earthen pipe and ceiling ventilation, and vertical side wall and ceiling ventilation systems have been proved to be most effective for natural ventilation. 4. The experimental results have shown that ventilation systems such as the vertical side wall and underground ventilation systems are suitable to put to practical use as natural ventilation systems for farm mushroom houses. These ventilation systems can remarkably improve the temperature of fresh air which is introduced into the house by heat transfers within the ventilation passages, so as to approach to the desired temperature of the house without any cooling or heating operation. For example, if it is assuming that x is the outside temperature and y is the amount of temperature adjustment made by the influence of the ventilation system, the relationships that exist between x and y can be expressed by the following regression lines. Underground iron pipe ventilation system ${\cdots}{\cdots}$ y=0.9x-12.8 Underground earthen pipe ventilation system ${\cdots}{\cdots}$y=0.96x-15.11 Vertical side wall ventilation system${\cdots}{\cdots}$ y=0.94x-17.57 5. The experimental results have shown that the relationships existing between the admitted and expelled air and the $Co_2$ concentration can be described with experimental regression lines or an exponent equation as follows: 1) If it is assumed that x is an air speed cm/sec. and y is an expelled air speed in cm/sec. in a natural ventilation system, since the y is a function of the x, the relationships that exist between x and y can be expressed by the regression lines shown below: 2) If it is assumed that x is an admitted volume of air in $m^3/hr$ and y is an expelled volume of air in $m^3/hr$ in a natural ventilation system, since the y is a function of the x, the relationships that exist between x and y can be expressed by the regression lines shown below. 3) If it is assumed that the expelled air speed in cm/sec and replacement air speed in cm/sec. at the bed surface in a natural ventilation system are shown as x and y, respectively, since the y is a function of the x, the relationships that exist between x and y can be expressed by the following regression line: G.E. (100%)- C.V. (50%) ventilation system${\cdots}$ y=0.54X+0.84 4) If it is assumed that the replacement air speed in cm/sec. at the bed surface is shown as x, and $CO_2$ concentration which is expressed by multiplying 1000 times the actual value of $CO_2$ % is shown as y, in a natural ventilation system, since the y is a function of the x the relationships that exist between x and y can be expressed by the following regression line: G.E. (100%)- C.V. (50%) ventilation system${\cdots}{\cdots}$ y=114.53-6.42x 5) If it is assumed that the expelled volume of air is shown as x and the $CO_2$ concentration which is expressed by multiplying 1000 times the actual of $CO_2$ % is shown as y in a natural ventilation system, since the y is a function of of the x, the relationships that exist between x and y can be expressed by the following exponent equation: G.E. (100%)-C.V. (50%) ventilation system${\cdots}{\cdots}$ $$y=127.18{\times}1.0093^{-X}$$ 6. The experimental results have shown that the ratios of the crass sectional area of the G.E. and C.V. vent to the total cubic capacity of the house, required for providing an adequate amount of air in a natural ventilation system, can be estimated as follows: G.E. (admitting vent of the underground ventilation)${\cdots}{\cdots}$ 0.30-0.5% (controllable) C.V. (expelling vent of the ceiling ventilation)${\cdots}{\cdots}$ 0.8-1.0% (controllable) 7. Among several heating devices which were studied in the experiments, the hot-water boilor which was modified to be fitted both as hot-water toiler and as a pressureless steam-water was found most suitable for farm mushroom growing.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.7
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• pp.688-693
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• 2005

Nowaday the natural ventilation rate decreases because the apartment housing is being air-tight. Therefore, Indoor Air Quality (IAQ) and indoor environment grow worse. Especially, Formaldehyde (HCHO), Volatile Organic Compounds (VOCs) which is emitted from the building materials and coating material etc. occur Sick House Syndrome that cause negative impact on resident's respiratory system and body. Therefore in construction field, it will be a important issues that development of a ventilation system with high effectiveness which can exhaust the contaminant out of the building quickly. In this research we evaluated 'wall attachable duct-less Heat Recovery Ventilation (HRV) system with air cleaning function'. We executed a synthetic evaluation about indoor air environment under various operating condition installing the system in real scale apartment house that is built in Anyang city. HRV system with air cleaning function showed good performance by removing HCHO, VOCs with less ventilation energy.

• Journal of Fisheries and Marine Sciences Education
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• v.21 no.2
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• pp.269-277
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• 2009

Ventilation equipment performs a central role to maintain comfort subway environment. So ventilation equipment of Busan subway line No.1 is required to improve thermal environment. In this study, conditions of thermal environment are presented to improve ventilation equipment at existing subway station platforms by measuring thermal environment of platforms operated ventilation equipment at 14 stations of Busan subway line No.1. AWS of data in comparison with the neighbouring platforms and thermal environment analysis. Thermal environment status of subway platform analysis results are as follows. 1)Daytime platform temperature was higher than outdoor temperature, but night time platform temperature was lower than outdoor temperature. 2)Train wind had effect on improving thermal comfort in platform. 3)When outdoor temperature is below $24^{\circ}C$, inlet air is able to lower than platform temperature. 4)Considering existing ventilation system, night purge systems is useful to improving platform thermal environment.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1238-1243
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• 2009

As Social Overhead Capital(SOC) has been expanded, the highway road construction has been accelerated and city road system has been more complicated. So, long road tunnels have been increased and traffic flow rate also has been raised. Accordingly, the exhausting gas of vehicle cars seriously deteriorates the tunnel inside air quality and driving view. In order to improve tunnel inside air quality, it is needed to introduce a compulsory ventilation system as well as natural ventilation mechanism. The former, that is, a special compulsory ventilation facility is very useful and helpful to prevent a tunnel of being contaminated by traffic in most case. In the case of obtaining clearer and longer driving view, the ventilation systems have to be considered in order to remove floating contaminants or exhaust gas from engines. In this paper, discharge electrode design technology will be discussed.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.3
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• pp.201-209
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• 2016

Supercavitation is a technology that reduces frictional resistance of an underwater vehicle by surrounding it with bubbles. Supercavity is divided into natural supercavity and ventilated supercavity which is formed by artificially supplying gas. Planing forces are present when a section of the underwater vehicle goes outside of the cavitation region in the supercavity condition. Planing often leads to an unstable flight because it acts vertically on the body suddenly. In this paper, a relationship between the ventilation rate and the cavitation number is determined. Based on the relationship, desired cavitation number which can avoid to planing is determined and then ventilation controller is designed. The performance of the ventilation controller is verified with a depth change controller using the cavitator. Simulation results show that the ventilation controller can minimize the planing force and moment.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.7-10
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• 2011

According to the requirement of Res.MSC.285(86) for natural gas-fueled engine installations in ships, pump and compressor rooms should be fitted with effective mechanical ventilation system of the under pressure type, providing a ventilation capacity of at least 30 air changes per hour. It generally considered that gas leakage is more likely from a Fueled Gas Supply System(FGS) room as compared to other places, where installed in many kind of machinery or equipments like gas supply high-pressure pipes, valves, flanges and etc. Furthermore, leaked gas may be dispersed in a short time in an enclosed space, especially a FGS room, due to high pressure. However, the present requirement in Res.MSC.285(86) just considers the ventilating capacity of air changes per hour but the capacity of leaked gas. Hence, the current requirements may not meet effectively when enforcing the new propulsion systems as marine fuel. This study is conducted for the purpose of safety evaluation about the dispersion and ventilation efficiency with estimated leakage scenario. Numerical analysis predictions as the result of this paper are explained to know the features of flow pattern and the diffusion of natural gas concentration.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.5
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• pp.468-476
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• 2005

The purpose of this study is to investigate actual air quality in newly-constructed multi-family houses and to improve Indoor Air Quality (IAQ). The field measurement was conducted in four different newly-constructed multi-family house complexes in Seoul and one existing multi-family house complex in Kyong-gi province. The result of the measurement shows that indoor concentrations of Formaldehyde and TVOC in newly-constructed multi-family houses are much higher than the foreign standards. To establish a proper process for reducing indoor air pollutants, various experiments have been conducted; application of natural materials, bake-out practice, closure of all openings without ventilation, and use of mechanical ventilation system. The result indicates that three practices (natural materials, bakeout, mechanical ventilation) can reduce the level of indoor air pollutants almost in half during the experiments. However, each practice has its limitation and is insufficient to satisfy IAQ standards. Therefore, the study proposes a proper reduction process of indoor air pollutants which combines four different practices in time sequence.

• Agricultural and Biosystems Engineering
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• v.1 no.2
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• pp.73-80
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• 2000

Aerodynamics in a naturally ventilated multi-span greenhouse with plants was analyzed numerically by the computational fluid dynamics (CFD) simulation. To investigate the potential application of CFD techniques to greenhouse design and analysis, the numerical results of the CFD model were compared with the results of a steady-state mass and energy balance numerical model. Assuming the results of the mass and energy balance model as the standard, reasonably good agreement was obtained between the natural ventilation rates computed by the CFD numerical model and the mass and energy balance model. The steady-state CFD model during a sunny day showed negative errors as high as 15% in the morning and comparable positive errors in the afternoon. Such errors assumed to be due to heat storage in the floor, benches, and greenhouse structure. For a west wind of 2.5 m s$^{-1}$ , the internal nonporous shading screens that opened to the east were predicted to have a 15.6% better air exchange rate than opened to the west. It was generally predicted that the presence of nonporous internal shading screens significantly reduced natural ventilation if the horizontal opening of the screen for each span was smaller that the effective roof vent opening.