• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.2
• /
• pp.319-333
• /
• 2017

The construction of long sub-sea tunnel does not provide the favorable condition for the installation of ventilation system to be used during construction due to the constrained construction space. For the ventilation system required during construction, the artificial island where ventilation shaft is located is constructed at some location along the sub-sea tunnel route, which requires a high construction cost. Therefore, it is intended, as much as possible technically, to minimize the construction of artificial island. However, this requires a longer distance between ventilation shafts, there-by causing increased air leakage at the ventilation duct connection points due to the higher fan pressure being required to deliver ventilation air. Previously the air leakage was studied as an important issue. In this study experiments were carried out to develop the improved duct connection method considering various conditions such as, tunnel length, etc. Additionally, its performance results with leakage rates are shown and compared to the "S" class leakage rate of SIA. As a result, the new duct coupling type of improved method is analyzed as applicable to such a 30 km long tunnel with the leakage rate of $1.46mm^2/m^2$, which is better performance than SIA leakage rates.

• Journal of Korean Academy of Nursing
• /
• v.21 no.3
• /
• pp.268-280
• /
• 1991

The nursing intervention for the prevention of the pulmonary complication and of the function lowering of pulmonary ventilation which emerge with high generation frequency during the nursing of operation patient is necessary for performing the qualitative nursing for operation patient. So, this researcher tried this study so as to obtain the data which can be utilized for the trial of nursing intervention, by grasping the effect that the deep breathing with Incentive Spirometer has on the function of pulmonary ventilation, analysing the factor to have influence on the function of pulmonary ventilation, and applying the effective method of deep breathing to the clinic. By making 42 patients who underwent the operation of upper abdomen after admitting G Hospital in Seoul from Mar. 7, 1991 to Apr.30, 1991 as the object, they were classified into the experiment group that the deep breathing was made with the use of Incentive Spiromenter and the comparison group that the deep breathing exercise was made without the use of Incentive Spirometer. And then, by measuring Tidal Volume and Forced Vital Capacity with Respirometer and $O_2$ Saturation with Pulse Oximeter at preoperation postoperation 24 hours, 72 hours, and 120 hours data were collected. The collected data were analyzed with of, average, standard deviation, x$^2$-test, t-test and ANOVA by SPSS. The result of this study is as follows : 1. As for the hypothesis that the function of pulmonary ventilation at postoperation 24 hours, 72 hours and 120 hours will be better in the experiment group that the deep breathing was made with the use of Incentive Spirometer, in comparison with the comparison group that deep breathing was made without the use of Incentive Spirometer, experiment group and comparison group didn't show the significant difference in Tidal Volume, Foreced Vital Capacity and $O_2$ Saturation at postoperation 24 hours and 72 hours. But experiment group and comparison group showed the significant difference in Tidal Volume at postoperation 120 hours (p＜0.01). So, this hypothesis was supported partially. 2. The variables that there were the significant differences about the function of pulmonary ventilation in experiment group at postoperation 24 hours stastically were smoking existence (p＜0.05), and the variables that there were not significant differences about the function of pulmonary ventilation were distinction of sex, age, anesthetic duration, smoking extent, body weight, surface area of body, existence of narcotic use, regular exercise existence, and past experience existence of respiratory disease. As above result, it appeared that the method of deep breathing with the use of the Incentive Spirometer is more effective for the function recovery of pulmonary ventilation, in comparison with the deep breathing without use of Incentive Spirometer and that smoking existence was the factor to have influence on the function of pulmonary ventilation. In the aspect of clinic, the trial of nursing intervention of deep breathing with use of Incentive Spirometer is expected. And, in the aspect of study, the study through various operative site patients about the effect of Incentive Spirometer use at the clinic will have to be confirmed.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.4
• /
• pp.610-619
• /
• 2022

Hydrogen is emerging as an alternative fuel for eco-friendly ships because it reacts with oxygen to produce electrical energy and only water as a by-product. However, unlike regular fossil fuels, hydrogen has a material with a high risk of explosion due to its low ignition point and high flammability range. In order to safely use hydrogen in ships, it is an essential task to study the flow characteristics of hydrogen leakage and diffusion need to be studied. In this study, a numerical analysis was performed on the effect of leakage, ventilation, etc. on ventilation performance when hydrogen leaks in an enclosed space such as inside a ship. ANSYS CFX ver 18.1, a commercial CFD software, was used for numerical analysis. The leakage rate was changed to 1 q, 2 q, and 3 q at 1 q = 1 g/s, the ventilation rate was changed to 1 Q, 2 Q and 3 Q at 1 Q = 0.91 m/s, and the ventilation method was changed to type I, type II, type III to analyze the ventilation performance was analyzed. As the amount of leakage increased from 1 q to 3 q, the HMF in the storage room was about 2.4 to 3.0 times higher. Furthermore, the amount of ventilation to reduce the risk of explosion should be at least 2 Q, and it was established that type III was the most suitable method for the formation of negative pressure inside the hydrogen tank storage room.

• Journal of Advanced Marine Engineering and Technology
• /
• v.21 no.3
• /
• pp.229-235
• /
• 1997

The comparison of radiative and convective heat transfer in a room air ventilation is investi¬gated by a numerical simulation. The room air temperature distributions with radiation are appeared more uniform than without radiation at Gr= 1460 and Re=50. The mean Nusselt number in the radiative heat transfer shows less value than convective heat transfer. The total mean Nusselt number is found Wall 1> Wall 3${\fallingdotseq}$Wall 2 7 Wall 4.

• Journal of Advanced Marine Engineering and Technology
• /
• v.30 no.2
• /
• pp.267-274
• /
• 2006

There are no solar loads through windows and heat transfer from outer walls of the building to the interior This study analyzes indoor air temperature and air flow distribution for the interior of buildings or vessels occupying space. Numerical method is adopted to visualize the indoor side environmental situation. that is without heat transmission to outside the building in various cooling load conditions; supply ventilation lighting. occupancy and infiltration in conditioned spaces. Reaching time of an air conditioner is predicted theoretically by cooling load variations. Theoretical modelling of the reaching time shows good agreement with experimental results.

• The Journal of the Acoustical Society of Korea
• /
• v.32 no.1
• /
• pp.43-55
• /
• 2013

The window ventilation system based on the heat recovery device was developed which make air ventilation possible without opening the windows. However, mechanical and aerodynamic noises were come to pass which annoyed people in rooms. In the present study, noise of new window ventilation system was measured in both general room and anechoic chamber. Also, the noise path was detected to find cause of noise generation and vulnerable area of the device. Sound absorptive and insulation materials were applied to mitigate the noise. Finally, an alternative noise control method was suggested which can satisfy with the indoor noise standards. As a result, it was shown that the cause of noise was the low transmission loss in the ventilation system. As a result, it was shown that the main noise source of the ventilation system was the blower and the major cause of noise was the low transmission loss of the ventilation system. It is also concluded that the noise levels complies with the noise standards of 40 dBA when 2 mm rubber sheet is applied inside the ventilation system.

• KIEAE Journal
• /
• v.15 no.6
• /
• pp.81-86
• /
• 2015

Purpose: Condensation in the apartment housing is one of the most significant defects and complaints for condensation are rapidly increasing according to the growing interest in residential environment. Korea government established a regulation for reducing condensation in the apartment housing and TDR is adapted as a standard. However prevention of condensation depend on improving the performance of building envelop has limitation because of the increase of the cost. Centralized Hybrid ventilation system is suggested to prevent condensation. Method: Field measurement was conducted to verify the ventilation rate of the ventilation system. Based on the measurement, air network and CFD simulation was conducted to analyze ventilation rate for each room. Surface temperature was calculated by regulated TDR according to the regions and surfaces. The performance of condensation prevention was evaluated by the ventilation rate and surface temperature. Result: In the results, it was found that condensation was prevented in more than 90% of households by the centralized hybrid ventilation system which provided 0.19 ~ 0.81ACH for each room.

• 유체기계공업학회:학술대회논문집
• /
• 2006.08a
• /
• pp.269-272
• /
• 2006

The heat and smoke which generated by subway under fire is one of the most harmful factor in air tighten underground station. To prevent this, Trackway Exhaust System(TES) can be used. The heat released from the train running in the tunnel raises the temperature at the platform and the trackway, and thus proper ventilation system is required for comfortable underground environment. When the fire is occurred, TES is operated as smoke exhaust mode from normal ventilation mode. In the present study, the subway station which is one of the line number 9 in Seoul subway is modeled, and fired situation is simulated with several ventilation mode of ventilation system in trackway. For this simulation whole station is modeled. Non steady state 3D simulation which considered train under fire is entering to the station is performed. Temperature and smoke distribution in platform and trackway are compared. To represent heat by fire, heat flux was given to the fired carriage, also to describe smoke by fire, concentration of CO is represented. As the result of present study, temperature and smoke distribution is different as the method of ventilation in trackway and platform is changed. In over side of trackway, the fan must be operated as exhaust mode for efficient elimination of heat and smoke, and supply mode of fan operation in under side shows better distribution of heat and smoke. The ventilation system which is changed from ventilation mode to exhaust mode can be applied to control heat and smoke under fire.

• Journal of Mechanical Science and Technology
• /
• v.19 no.4
• /
• pp.1001-1005
• /
• 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.

• Proceedings of the SAREK Conference
• /
• 2008.11a
• /
• pp.469-474
• /
• 2008

The objective of this study is to propose basic design guidelines for more effective air ventilation system in apartments. It is well known that ventilation depends on whether the room doors are open or closed as well as people's living patterns. This study considers 84 ㎡-sized apartment which has extended living room without balcony. Ventilation of bathroom and kitchen is not considered. The height of the building, external air pressure and air infiltration through the windows are also neglected. The regulation on indoor air quality made it mandatory that the air change per hour be more than 0.7. Four models are suggested to study the effect of open and closed doors. Models 1 and 3 are open door types and models 2 and 4 are closed door types. The open types have 50 mm hole near the top of the door to substitute exhaust outlet. The ventilation effectiveness was evaluated by 3-dimensional numerical simulation using finite volume method by a commercial software. This work compares air flow, temperature of air, age of air and the efficiency of ventilation of apartments with wooden doors of bedroom 1 and 2, which are open or closed.