• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.11
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• pp.745-750
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• 2010

Since the implementation of the LMO Law in Korea, the importance of the design qualification of BSL3 lab. is emphasizing. In this study, multizone simulation for three kind of biohazard scenarios using CONTAM is performed for design qualification of BSL3 lab. Also, in the case of unexpected spread of contaminants such as Influenza A virus(H1N1) in BL3 zone, the design qualification is carried out for diffusion and decontamination of contaminants according to differential pressure of BSL3 anteroom and door area of BSL3 lab. Also, in this study, appropriateness of laboratory room differential pressure and air flow rate to maintain pressure difference between laboratory rooms, and energy consumption due to air change rate variation according to door area in BL3 lab. Simulation results show that these approach methods are used as a tool for the design and verification of BL3 lab.

• International Journal of Automotive Technology
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• v.6 no.2
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• pp.141-148
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• 2005

In order to reduce the time and costs of improving the performance of vehicle suspensions, the techniques for optimizing damping and air spring characteristic were proposed. A full vehicle model for a bus is constructed with a car body, front and rear suspension linkages, air springs, dampers, tires, and a steering system. An air spring and a damper are modeled with nonlinear characteristics using experimental data and a curve fitting technique. The objective function for ride quality is WRMS (Weighted RMS) of the power spectral density of the vertical acceleration at the driver's seat, middle seat and rear seat. The objective function for handling performance is the RMS (Root Mean Squares) of the roll angle, roll rate, yaw rate, and lateral acceleration at the center of gravity of a body during a lane change. The design variables are determined by damping coefficients, damping exponents and curve fitting parameters of air spring characteristic curves. The Taguchi method is used in order to investigate sensitivity of design variables. Since ride and handling performances are mutually conflicting characteristics, the validity of the developed optimum design procedure is demonstrated by comparing the trends of ride and handling performance indices with respect to the ratio of weighting factors. The global criterion method is proposed to obtain the solution of multi-objective optimization problem.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.8 no.1
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• pp.27-32
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• 1997

Recently, many people suffering from voice color change visit otolaryngologist. There is no specific data which can be evaluated objectively for voice color change in korean. In aerodynamic study, maximum phonation time, mean air flow rate, phonatory flow volume and subglottal pressure were tested by using Aerophone II voice function analyzer in korean. 112 male and 122 female aged from 10 to 69 years were randomly selected. Maximum phonation time was 20.8${\pm}$6.4sec in male and 17.2${\pm}$4.1sec in female. Mean air flow rate was 167.1${\pm}$61.4ml/sec. in male and 129.6${\pm}$49.3ml/sec in female. Phonatory flow volume was 3184.5${\pm}$646.0ml in male and 2122.1${\pm}$670.5ml in female. Subglottal pressure was 4.1${\pm}$1.8 cmH2O in male and 3.5${\pm}$1.4cm $H_2O$ in female. There was no statistically significant difference among age groups in all above results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1298-1303
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• 2008

Respiration is induced by muscular contraction of the chest and abdomen, resulting in the abdominal volume change. Thus, continuous measurement of the abdominal dimension enables to monitor breathing activity. Conductive rubber cord has been previously introduced and tested to develop wearable application for respiratory measurements. This study implemented respiratory monitoring system with the conductive rubber cord in the patient's pants in purpose of quantitative estimation of tidal volume. Air mixed with $0{\sim}5%$ $CO_2$ was inhaled and the respiratory air flow rate, abdominal dimension change, and end tidal $CO_2$ concentration were simultaneously measured in steady state. $CO_2$ inhalation significantly increased the tidal volume in normal physiological state with the subject unawared. The tidal volume estimated from the abdominal dimension change linearly correlated with the tidal volume measured by a pneumotachometer with a correlation coefficient of 0.88. Customized calibration for each subject resulted in relative errors less than 10%. Therefore, the tidal volume was accurately estimated by measuring the abdominal dimension change.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.1
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• pp.54-62
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• 2015

Small scale paint overspray booths are being operated nationwidely, for repair of passenger car body parts. paint aerosols are emitted from the paint overspray booth in operations. In paint overspray booth operations without ventilation system and air pollutants collection unit, it may land on nearby equipment. In this study a removal of sticky paint aerosol for application of the small-scale overspray paint booth. it's cause the surface of filter bag from generated sticky paint aerosol. To remove adhesion of paint aerosol the agglomerating agents are injected and mixed with sticky paint aerosols prior to reach the filter bag. The paint spray rate was set as $10{\pm}5g/min$ from air-atomized spray guns in the spray booth, injection rate of agglomerating was $10{\pm}5g/min$ in the mixing chamber. The filtration velocity including air pollutants varied from 0.2 m/min to 0.4 m/min. Bag cleaning air pressure was set as $5.0kg_f/min$ for detaching dust cake from surface of filter bag. Bag cleaning interval at the filtration velocity of 0.2 m/min was around 3 times longer than that of the 0.4 m/min. The residual pressure drop maintained highest value at the highest filtration velocity. Fractional efficiency of 99.952%~99.971% was possible to maintain for the particle size of 2.5 microns. Total collection efficiency at the filtration velocity of 0.2 m/min was 99.42%. During this study we could confirm high collection efficiency and long cleaning intervals for the test with filtration velocity of 0.2 m/min indicating an optimal value for the given dimensions of the test unit and test operating conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.51-60
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• 2002

An analysis method to predict performance of a vehicle cooling system which is composed of radiator, A/C condenser, cooling fan, and etc. is suggested. Air flow through the heat exchanger system and heat rejection rate which dominate the cooling performance are analyzed. Heat transfer with A/C refrigerant phase change is also considered in the analysis. Some predicted results are compared with experimental data for various operating conditions. This evaluation procedure will be useful for the design of optimal vehicle cooling system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.1
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• pp.29-38
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• 1994

Particle contamination into and out of a cavity-cylindrical cavities with aspect ratios(width/depth) less than, equal to 1 and langer than 1, and also three dianensional T's attached to a cylindrical flow tube was studied numerically, using a finite difference method. In the process of unsteady particle diffusion, the particles contained in a concentration boundary layer near the tube wall plays an important role in the initial stage, after which a quasi-steady concentration profile is developed inside the cavity, resulting in an exponential change of concentration with time. Average concentration and its rate of change are observed to be closely correlated by a power law function in terms of Reynolds number and the logarithm of Schmidt number. Effects of the three parameters-Re, Sc, and aspect ratio-are analysed and well explained.

• Journal of Mechanical Science and Technology
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• v.18 no.5
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• pp.857-864
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• 2004

The change in the NO emission indices (EINO) in a two-dimensional plane has been investigated, which is due to the interaction between a vortex and methane-air flames established at different equivalence ratios, by solving the field equation. After solving the field equation, the spatial distribution of G-values is obtained. The NO emission index is calculated after applying the appropriate relation between the G-values and the NO production rate or the mass fraction of methane obtained from the library of freely propagating flames created from detailed simulations. When a vortex exists in a reacting flow field, in general EINO slightly increases, whereas ElNO is lowered in the vicinity of the vortex regardless of flow direction. A change in vortex size has negligible impact on EINO$\_$T/ but increasing the vortex strength slightly increases EINO$\_$T/ in the domain of this study.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.1-11
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• 2000

This study investigates the problem of phase change from liquid to solid in the inviscid stagnation flow. The solution of dimensionless governing equations is determined by the three dimensionless parameters of (temperature ratio/conductivity ratio), Stefan number, and diffusi-vity ratio. The solution at the initial stage of freezing is obtained by expanding it in powers of time, and the final equilibrium state is determined from the steady-state governing equations. The equilibrium state is dependent on (temperature ratio/conductivity ratio), but is independent of Stefan number and diffusivity ratio. The effect of fluid flow on the pure conduction problem can be clearly seen from the solution of the initial stage and the final equilibrium state, and the characteristics of the solidification process for all the dimensionless parameters are elucidated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.6 s.261
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• pp.531-538
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• 2007

In this study, an air conditioning system using carbon dioxide as a refrigerant was developed for automotive cabin cooling. Experiments have been carried out to examine the steady state and dynamic characteristics of this system. The system consists of a compressor, a gas cooler, an evaporator, an expansion device, an internal heat exchanger and an accumulator. The compressor is a variable displacement type, driven by the electric motor, and the gas cooler and the evaporator are aluminum extruded heat exchangers of micro channel type. The $CO_2-refrigerant$ charge, the compressor speed, the air inlet temperature of the gas cooler, the air inlet temperature and the air flow rate of the evaporator and the cooling load are varied and the performance of the system is experimentally investigated. As the compressor speed increased, cooling capacity increased, but the coefficient of performance was deteriorated. As the cabin air temperature or the air flow rate to the cabin was set high, both the cooling capacity and the COP increased. In the cool down experiment with 1.0 or 2.0 kW of heat load, the dynamic characteristics of the air-conditioning system were investigated. For a given capacity of compressor, cool down speed was monitored, and the temperature change was acceptable fur low heat load condition.