• Journal of the Korean Society of Tobacco Science
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• v.23 no.1
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• pp.60-64
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• 2001

The variability of a ventilated filter cigarette depends on the details of its construction and one properties of its components and the variations in filter ventilation is effected by many factors such as tobacco column pressure drop, filter pressure drop, tipping paper and plug wrap permeability, and vent position. In this study, the effects of combination of tipping paper and plug wrap on filter ventilation of cigarettes were studied for the target ventilation level under the specific tobacco column and filter tip in order to reduce the variation of filter ventilation. When Nicolas Baskevitch\`s equation on filter ventilation was used to try out Monte Carlo Simulation, at the combination where tipping paper permeability is high and plug wrap permeability is low, even the small change in tipping paper and plug wrap permeability showed high variation of target ventilation level. Also, according to the analysis data of filter ventilation in cigarettes designed at the level of 45% filter ventilation by the combinations with tipping paper and plug wrap, the variation in cigarette filter ventilation was increased as increasing tipping paper permeability and decreasing plug wrap permeability. As the results of this study, the variation of filter ventilation can be reduced by increasing plug wrap permeability/tipping paper permeability ratio in the cigarette design, considering 2-3% of tipping paper permeability variation(%CV) and about 10% of plugwrap permeability variation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.2
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• pp.142-148
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• 2007

The purpose of this study is to suggest the effective ventilation strategies and control methods that can minimize energy cost maintaining acceptable IAQ level in apartment house. The effects of the air-cleaning and heat-recovery ventilation system on IAQ under various operating conditions are investigated based on the experimental and CFD analyzed results. The results can be summarized as follows. (1) When a ventilator is not operated, the concentration of several pollutants may highly show in the house even though environment-friendly building materials are applied. Therefore, a mechanical ventilation system is required to obtain proper ventilation. (2) The pollutant concentration is noticeably deceased under air-cleaning/ventilation mode of air-clinic system, however, pollutant of kitchen is stagnant, because fresh air is not carried into the kitchen. (3) When air-clinic system is only equipped at master bedroom and living room, the system does not effectively deliver fresh air throughout the whole house, and then high pollutant concentration is obtained in each room. In contrast the average pollutant concentration meets the guideline when air-clinic system is installed at each room. (4) The air-cleaning/ventilation mode significantly affects on room ventilation in comparison with ventilation mode only.

• Journal of the Korean Society of Clothing and Textiles
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• v.16 no.1 s.41
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• pp.53-63
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• 1992

The purpose of this study is to investigate the method of trace gas technique by G.C and the effects of the type of blouse on ventilation. The experimental system employed a trace gas technique in which ventilation was monitored to determine oxigen exchange rate. The experimental variables were tested with three types of blouse depending on the sizes of neckline, armhole and waist line. Exercise conditions include standing and walking position. The results and discussion forcused on the construct validity of the apparatus/testing protocol. the effect of experimental variables on ventilation was also discussed.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.26 no.2
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• pp.136-143
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• 2019

Purpose: The feasibility and differential effects of two music therapy methods (interventions with preferred music vs. classical relaxation music) were done to examine the effects on agitation and anxiety in patients weaning off mechanical ventilation. Methods: This pilot study was conducted using a crossover design. Six patients listened to preferred music choices and classical relaxation music. Anxiety scores were measured using the Richmond Agitation Sedation Scale (RASS), State-Trait Anxiety Inventory (STAI), and visual analog scale (VAS). Results: Patients showed a significant decrease in agitation and anxiety after both the preferred and classical relaxation music interventions. The difference in the effects of preferred music and that of classical relaxation music was not significant. As for feasibility, patients exhibited a change in agitated behaviors after the music interventions by not trying to take off medical devices and quietly listening to the music, and by smiling and moving lips along with the lyrics while listening. Conclusion: Music interventions which centered on either patients' preferences or classical relaxation music to enhance relaxation, helped reduce agitation and anxiety during the mechanical ventilation weaning process.

• Wind and Structures
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• v.20 no.3
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• pp.449-468
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• 2015

Current wind-resistance designs of large-scale indirect dry cooling towers (IDCTs) exclude an important factor: the influence of the ventilation rate for radiator shutter on wind loads on the outer surfaces of the tower shell. More seemingly overlooked aspects are the effects of various ventilation rates on the wind pressure distribution on the tower surfaces of two IDCTs, and the feature of the flow field around them. In order to investigate the effects of the radiator shutter ventilation rates on the aerodynamic interference between IDCTs, this paper established the numerical wind tunnel model based on the Computational Fluid Dynamic (CFD) technology, and analyzed the influences of various radiator shutter ventilation rates on the aerodynamic loads acting upon a single and two extra-large IDCTs during building, installation, and operation stages. Through the comparison with the results of physical wind tunnel test and different design codes, the results indicated that: the influence of the ventilation rate on the flow field and shape coefficients on the outer surface of a single IDCT is weak, and the curve of mean shape coefficients is close to the reference curve provided by the current design code. In a two-tower combination, the ventilation rate significantly affects the downwind surface of the front tower and the upwind surface of the back tower, and the larger positive pressure shifts down along the upwind surface of the back tower as the ventilation rate increases. The ventilation rate significantly influences the drag force coefficient of the back tower in a two-tower combination, the drag force coefficient increases with the ventilation rate and reaches the maximum in a building status of full ventilation, and the maximum drag coefficient is 11% greater than that with complete closure.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.778-783
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• 2008

In this paper, numerical method was calculated on evaluation of underground ventilation system to keep servicing a fresh air. The tunnel length for simulation is 18.2 km with various located seven ventilation shaft. Generally, owing to thermal generation in cable tunnel under about 50 m depths, cable tunnel ventilation system is more important than that of other tunnels. So, we conducted that the effects of ventilation systems was simulated depending on the difference of electrical power tunnel length, the number of shaft tunnel, forced ventilation and duct was or not. Test results show that the main conditions in order to enhance the underground cable tunnel are that ventilation systems have to be designed with forced ventilation and with duct.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.337-343
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• 2015

This paper investigates the ventilation characteristics in a two-dimensional underground network junction composed of four main lines interconnected by eight ramps. Simple one-dimensional models cannot be applied to network junctions since there are interferences of traffic piston effects in the main lines and at the ramps. A numerical algorithm was developed to analyze the pressure and airflow distributions iteratively. The Darcy-Weisbach equation was used to calculate the piston effects by traffic flows, and a Hardy Cross iteration was conducted for network analysis at the interconnected junction. The results show interesting ventilation characteristics and CO concentration distributions depending on system parameters such as vehicle speed, tunnel diameter, and other junction configurations.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.8
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• pp.1387-1395
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• 1997

Effects of the ambient air temperature and the opening position on the pattern of the clothing ventilation of a thermal manikin wearing an impermeable blouse were investigated by the trace gas method. Under an isothermal condition, the ventilation was governed by diffusion, and the ventilation rate through the wrist-openings was greatly affected by the distance from the openings. Under non-isothermal conditions, however, the ventilation was accelerated by the convection driven by the temperature gradient between the clothing microclimate and the surrounding air; the greater the temperature gradient, the greater the ventilation. Even though it was certainly affected by the ambient air temperature, the ventilation rate was more significantly influenced by the position of openings. The ventilation patterns at the arm and the body were distinctive.

• The Korean Journal of Emergency Medical Services
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• v.26 no.3
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• pp.37-46
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• 2022

Purpose: TThe experiment was designed to compare the efficiency of ventilation between conventional BVM ventilation and a newly devised A-BVM ventilation method with Tidal volume, total ventilation rate, average Ventilation speed, and average Ventilation volume. Methods: 40 Paramedical students who agreed to participate in the study were analyzed. Values were measured using IMB PASS after 2 minutes of Brayden Pro manikin with BVM and A-BVM ventilation. The difference in general characteristics was assessed by t-test and ANOVA and the difference in ventilation methods was analyzed by IBM SPSS. Results: A significant difference was found between the two ventilation methods in terms of tidal volume (t=-11.203, p<.001), ventilation time (t=-3.834, p<.001), and optimum ventilation probability (t=10.770, p<.001). A-BVM ventilation method, rather than BVM ventilation method, showed a value close to the appropriate amount recommended by Korean Advanced Life Support (500~600mL) in tidal volume, and higher in optimum ventilation probability. Conclusion: We could identify the a better mode of ventilation. Further studies on the efficacy of existing BVM ventilation methods as compared to device augmented BVM ventilation methods should be carried out to ensure that adequate ventilation is available to patients in clinical practice.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.6
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• pp.543-550
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• 2003

In order to saving the energy for HVAC system of buildings, utilization of wind-induced cross ventilation is thought to be promising. However, utilization of natural ventilation alone is not sufficient for maintaining the human thermal-comfort such as in hot and humid regions. A hybrid air conditioning system with a controlled natural ventilation system, or combination of natural ventilation with mechanical air conditioning is thought to overcome the deficiency of wind-driven cross ventilation and to have significant effects on energy reduction. This paper describes a concept of hybrid system and propose a new type of hybrid system using radiational cooling with wind-induced cross ventilation. Moreover, a radiational cooling system is compared with an all-air cooling system. The characteristics of the indoor environment will be examined through CFD (Computational Fluid Dynamics) simulation, which is coupled with a radiation heat transfer simulation and with HVAC control in which the PMV value for the human model in the center of the room is controlled to attain the target value.