• Journal of Korean Society for Atmospheric Environment
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• v.20 no.E1
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• pp.35-41
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• 2004

Aerosol wall loss is an important factor affecting smog chamber experiments, especially with chambers made of Teflon film. In this work, the aerosol wall loss was investigated in 2.5 and $5.8-m^3$ cubic-shaped Teflon film chambers filled with ambient air. The natural change in the particle size distribution was measured using a scanning mobility particle sizer in a dark environment. The rate of aerosol wall loss was obtained from the deposition theory suggested by Crump and Seinfeld (1981). The measured rates of aero-sol wall loss were In a good agreement with the theoretical and experimental values given by McMurry and Rader (1985), implying that the electrostatic effect enhances particle deposition on the chamber wall. The significance of aerosol wall loss correction was demonstrated with the photochemical reaction experiments using the ambient air.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1637-1639
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• 2001

Air arc interruption used in low rated voltage breaker, ACB and MCCB, have used the arc chamber composed of metal plates and insulating laminates which supposed these mechanically. and geometry and materials of arc chamber are very different by breaker manufacturer. These breakers have required to be smaller and to interrupt higher current by user. therefore the arc chamber geometry and material in breaker have been small, complex and various. The purpose of this study is to examine the effects of insulating laminates and contact materials on air arc interruption. Contacts were surrounded by a rectangle chamber of insulating laminates. Contact concoctions were composed of AgW, AgCdO that have used in low rated voltage breaker, and insulating laminates were polyester, epoxy. We found strong dependance of arc voltage on insulating material. The ablated vapor on polyester increased arc voltage that was useful in air arc interruption.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.4
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• pp.201-209
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• 1996

This study describes the combustion characteristics of methance-air mixture with various equivalence retio and initial conditions of mixture in constant volume combustion chamber. Combustion characteristics of methane-air mixture such as combustion pressure, combustion temperature, and heat release were investigated by the measurement of combustion pressure and temperature in the combustion chamber. The results show that maximum combustion pressure, gas temperature and rate of heat release have peaks at equivalence ratio of 1.1. Combustion duration is also the shortest at the equivalence ratio of 1.1 and it is shortened as initial mixture temperature increases.

• Journal of Korean Port Research
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• v.10 no.1
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• pp.25-36
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• 1996

Generally, it is pointed out that a nonlinear analysis is needed to estimate accurately the water surface fluctuation and dynamic responses of a floating structure in case of large wave reflection. In this study, a frequency-domain method is applied and newly developed to analyze the nonlinear characteristics of the air-chamber floating breakwater. The air-chamber floating breakwater in this study can control well the wave transformation, motions of the structure and its natural frequency by adjusting the air depth in the chamber. Experiments are carried out to verify the numerical results. It is appeared that the mean water level is setup in the anti-node and setdown in the node, while the nonlinearity in wave profile is larger in the node than in the anti-node. Because of vertical mooring system, the sway, especially the time-independent nonlinear component, plays predominant role in the motion. On the other hand, the time-dependent component, as well as the time-independent one to the tensile force of mooring line contributes greatly, and the time averaged value presents tensional force oriented to the onshore side due drift force.

• Journal of the Korean Society of Visualization
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• v.14 no.3
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• pp.51-58
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• 2016

New concept spark plug was developed to study its influence on the combustion characteristics of SI engine. It has pre-ignition chamber at the lower end of spark plug and flame hole, in which fresh mixture gas can be put in through the flame hole without any fuel supply system. This spark plug was tested in a single cylinder engine dynamometer for different air fuel ratio to measure the fuel consumption rate, emission gases, and MBT timing. And constant volume combustion chamber was made to understand flame characteristics of spark plug. New spark plug induced fast burn compared to the conventional spark plug and its effects were increased in lean air fuel ratio. Pre-ignition chamber spark plug with 5 holes which had adjusted size was more stable and effective in combustion performance than pre-ignition chamber spark plug with 1 hole. And its effects showed larger differences in lean air fuel ratio than stoichiometric condition. Flame kernel and flame growth process of conventional spark plug and pre-ignition chamber spark plug studied by flame visualization of schlieren method.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.277-282
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• 2006

In order to predict the indoor air pollutant, the VOCs emission rate is used through small chamber in the design process. However, the small chamber method has limitations as the convective mass transfer coefficient, the most important factor when predicting VOCs contamination of indoor air, is different between the small chamber result and the measured data in the actual building. Furthermore, the existing studies which analyzed mass transfer coefficient in the small chamber were directed on the small chambers developed at the time and FLEC(Field and Laboratory Emission Cell), thus, are different from the current small chamber which has been changed with improvements. The purpose of this study is to determine the emission rate of pollutant in double-layered building materials through the CFD(Computational of Fluid Dynamics) and Numerical analysis based on the mass transfer coefficient on singled-layered building material by using the current small chamber widely used in Korea. Futhermore, this study used the new convective mass transfer coefficient($h_m'$) which indicates the existing convective mass transfer coefficient($h_m$) including VOC partition coefficient(k). Also, formaldehyde was selected as target pollutant.

• Journal of the Korean Society of Combustion
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• v.11 no.2
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• pp.28-36
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• 2006

A constant volume combustion chamber was used to investigate the combustion characteristics. of homogeneous charge of methane-air mixture under various initial pressure, equivalence ratio and ignition times. The constant volume combustion chamber(CVCC) mostly has been studied by the experiments of visualization until now. So it is needed the numerical analysis of fluid and combustion characteristics in chamber by the more detail simulation. In this paper, the numerical analysis is tried to approach basically the homogeneous charge combustion phenomena under the various conditions, and the combustion phenomena in chamber is numerically analyzed by the commercial FIRE code. As a results, the combustion phenomena which were mean temperature, OH radical and reaction rate in chamber were investigated and it showed that the smallest flame growth occurs for the lean state and the increase of initial charged pressure condition due to the reduced OH radical.

• Journal of Environmental Health Sciences
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• v.43 no.1
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• pp.87-94
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• 2017

Objectives: This study was conducted to determine the impact of aquariums on indoor air quality for improving humidity and reducing indoor air pollutants. Methods: An air-conditioning chamber was used to determine humidity increase by aquarium volume at three different temperatures ($20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$). Humidity increase was measured for 21 hours ($20^{\circ}C$) and 12 hours ($25^{\circ}C$, $30^{\circ}C$) while placing five different volume of aquarium in the chamber. Concentrations of several volatile organic compounds and formaldehyde were measured after a known amount was injected into the chamber with and without an aquarium. Results: The humidity inside the chamber increased when the aquarium was inside the chamber. Humidity change was similar at $20^{\circ}C$, $25^{\circ}C$, and $30^{\circ}C$, but slightly higher at higher temperatures. The bigger the aquarium volume, the higher was the humidity increase that occurred. Humidity increase by the aquarium was sufficient to increase indoor humidity in winter and negligible in summer. Concentrations of some water-soluble indoor air pollutants and formaldehyde were decreased with the aquarium inside the chamber. Conclusions: An aquarium could increase indoor humidity in winter, while the humidity increase is negligible in summer. An aquarium could decrease some water-soluble indoor air pollutants, including formaldehyde. This result implies that an aquarium may have positive effects on indoor environmental quality.

• Journal of Biosystems Engineering
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• v.32 no.3
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• pp.166-172
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• 2007

Egg quality indices are related with freshness, size of air chamber, loss of weight, and viscosity of the yolk and the protein. However, since the described quality parameters require measured in a destructive way, it is not suitable to inspect the egg quality with complete enumeration. Therefore, this study was performed to investigate the potential of image analysis method for evaluation of internal egg quality. Samples of 90 fresh eggs were collected immediately after laying and stored up to 24 days. Five eggs were randomly drawn from each storage condition (packing vs unpacking) at a regular interval and loss of weight, specific gravity and size of air chamber were measured. The image analysis for nondestructive measurement of size of air chamber was also studied. Results showed that the egg weight and gravity gradually decreased with increasing of storage days, while the size of air chamber linear increased caused by evaporation of water through the shell. A relationship a between conventional method and the image analysis method for measuring the size of air chamber was developed with the correlation coefficient of 0.928. The new finding implied that image analysis might provide a useful nondestructive tool to assess internal egg quality.

• Particle and aerosol research
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• v.9 no.3
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• pp.149-161
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• 2013

Experiments on photochemical reactions of purified air alone in an indoor smog chamber were carried out after flushing Teflon bags with purified air for many hours in order to check the level of contamination on the chamber wall. Ozone concentrations were linearly increased from <4 ppb up to about 8 ppb with irradiation time for four hours. Outgassing of NOx from the chamber wall was found to be less than 1 ppb. New ultrafine particles were formed and grown up to about 70 nm during the photochemical reactions, and then total number and mass concentrations of particles were increased from <10 particles/$cm^3$ up to about 4,000 particles/$cm^3$ and $1.3{\mu}g/m^3$, respectively. The wall conditions of these Teflon bags flushed with purified air might not severly affect the chamber experimental results for photochemical reactions of polluted urban ambient air. The difference of gaseous species between two chambers was 2.4 ppb of ozone at most, indicating that the wall cleaning performance of two chambers was nearly similar.