• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.273-277
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• 2009

This paper presents a basic energy performance data of micro gas turbine, Renewable Energy(BIPV and Solar Collector System, geothermal system) and a hybrid energy system(geothermal system and microturbine) installed in Hospital Building. The efficiency of solar collector and BIPV system was 30%, 10% individually, and lower than micro gas turbines. Micro gas turbines are small gas turbines that bum gaseous and liquid fuels to produce a high-energy exhaust gas and to generate the electrical power. Recently, the size range for micro gas turbines is form 30 to 500kW and power-only generation or in combined heat and power(CHP) systems. Finally, in energy performance aspect, Micro gas turbine system and hybrid energy system were high-efficiency system in hospital building. Hybrid energy system also give us a powerful alternative energy system economically.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.209-214
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• 1998

A thermodynamic simulation method is developed for the process design and the performance evaluation of the gas turbine in IGCC power plant. The present study adopts four clean coal gases derived from four different coal gasification and gas clean-up processes as IGCC gas turbine fuel, and considers the integration design condition of the gas turbine with ASU(Air Separation Unit). In addition, the present simulation method includes compressor performance map and expander choking models for considering the off-design effects due to coal gas firing and ASU integration. The present prediction results show that the efficiency and the net power of the IGCC gas turbines are seperior to those of the natural gas fired one but they are decreased with the air extraction from gas turbine to ASU. The operation point of the IGCC gas turbine compressor is shifted to the higher pressure ratio condition far from the design point by reducing the air extraction ratio. The exhaust gas of the IGCC gas turbine has more abundant wast heat for the heat recovery steam generator than that of the natural gas fired gas turbine.

• Journal of Energy Engineering
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• v.18 no.4
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• pp.230-238
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• 2009

We study about small gas engine and fuel cell CHP (Combined Heat and Power) as the technologies for energy conservation and $CO_2$ emissions reduction. Korea government plans to use them in near future. This study quantitatively analyzed energy consumption and $CO_2$ emissions reduction potential of small CHP instead of existing electric power plant (coal steam, combined cycle and oil steam) using LEAP (Long-range Energy Alternative Planning system) as energy-economic model. Three future scenarios are discussed. In every scenario similar condition for each CHP is used. Alternative scenario I: about 6.34% reduction in $CO_2$ emissions is observed in 2019 due to increase in amount of gas engine CHP and fuel cell CHP while coal use in thermoelectric power plant is almost stagnant. In alternative scenario II: a small 0.8% increase in $CO_2$ emission is observed in 2019 keeping conditions similar to alternative scenario I but using natural gas in combined cycle power plant instead of coal. During alternative scenario II overall $CO_2$ emission reduction is observed in 2019 due to added heat production from CHP. Alternative scenario III: about 0.8% reduction in $CO_2$ emissions is observed in 2019 using similar CHP as AS I and AS II. Here coal and oil are used in thermoelectric power plant but the quantity of oil and coal is almost constant for next decade.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.1
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• pp.40-49
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• 2004

In this paper, vibration response of aerial gas pipeline due to vehicle loads was quantitatively estimated through experiment and analysis in open cut construction site. The vehicle vibration of various construction machines causes serious effect to the aerial gas pipeline. The new vibration prediction equations presented in this study can estimate the vibration velocity response of the aerial gas pipeline. In the nitration prediction equations, the vehicle′s weight and traveling velocity, which are the sources of vibration, are combined into the term called, "scaled weight" Methods to reduce vibration were proposed in case the vibration velocity response of the gas pipeline exceeded the vibration criterion, using the vibration prediction equations presented in this study. One was to limit the vehicle′s traveling velocity and the other to install the isolation equipment. Both methods can be estimated quantitatively.

• International Journal of Air-Conditioning and Refrigeration
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• v.6
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• pp.56-66
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• 1998

The absorption process of water vapor in a liquid film is an important process in LiBr-Water absorption system. The composition of the gas phase, in which a non-absorbable gas is combined with the absorbate, influences the transport characteristics. In the present work, the absorption processes of water vapor into aqueous solutions of lithium bromide in the presence of non-absorbable gas are investigated. The continuity, momentum, energy and diffusion equations for the solution film and gas are formulated in integral forms and solved numerically. It is found that the mass transfer resistance in gas phase increases with the concentration of non-absorbable gas. However the primary resistance to mass transfer is in the liquid phase. As the concentration of non-absorbable gas in the absorbate increases, the interfacial temperature and concentration of absorbate in solution decrease, which results in the reduction of absorption rate. The reduction of mass transfer rate is found to be significant for the addition of a small amount of non-absorbable gas to the pure vapor, especially at the outlet of tube where the non-absorbable gas accumulates. At higher non-absorbable gas concentration, the decrease of absorption rate seems to be linear to the concentration of non-absorbable gas.

• The Journal of Korean Academy of Sensory Integration
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• v.16 no.1
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• pp.1-13
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• 2018

Objective : The purpose of this study was to investigate the effects of sensory integration intervention combined with oral activity on eating of child with sensitive oral senses. Methods : The study subject was 6 years old boy and diagnosed with developmental disorder. The experiment period was 15 sessions from April 21, 2017 to June 2, 2017. Experimental design used AB design in single-subject design, baseline (A) phase (sensory integration therapy) was 5 sessions and intervention phase (B) (sensory integration therapy combined oral activity) was 10 sessions. During the experiment, the child used the Goal Attainment Scale (GAS) to measure behavioral changes in eating. Results : The GAS score of voluntary eating of favorite foods was 0 on the baseline phase and increased to 1.9 on the intervention phase. The GAS score of voluntary eating of disliking foods was 0 on average during the baseline phase and increased to 1.7 on average during the intervention phase. Conclusion : This study suggests that sensory integration intervention combined with oral activity program may have a positive effect on eating of children with sensitive oral senses and limited food intake.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.594-600
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• 2016

The present study numerically investigated the gas leakage characteristics in a simplified underground combined cycle power plant. The effect of obstacles near a crack location on the gas concentration in the confined space was analyzed by using the lower flammable limit (LFL) of methane gas. When the jet flow was close to the vertical walls, the longitudinal leakage distance increased by about 60% (when an obstacles was present) compared to the case without any obstacle, because these obstacles prevented transverse flows. In addition, when an air filter was installed near to the trajectory of the gas flow, the longitudinal leakage distance was similar to the distance between the crack and obstacle, whereas the transverse leakage distance increased up to 8 times compared to the case without any obstacle. As the jet flow impacts on the obstacle and changes its direction, the gas flows recirculate. Therefore, it is necessary to consider the effect of the structure and facility locations on the trajectory of the jet flow to propose an accident prevention system in confined spaces.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.118-124
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• 2017

In this study, a numerical simulation was performed using commercial code Fluent(v.17.1). The underground Combined Cycle Power Plant (CCPP) was simplified to analyze the methane gas leakage with the crack size and position. In addition, extensive numerical simulations were carried out for different crack sizes from 10 mm to 20 mm. The crack position is the gas leakage, which is assumed to be near the pipe elbow and the gas turbine. A total of 4 cases were compared and analyzed. To analyze the gas leakage, the concept of the Lower Flammable Limit (LFL) was applied. The leakage distance was defined in the longitudinal direction, and the transverse direction was estimated and quantitatively analyzed. As a result, the leakage distance in the longitudinal direction varies by 52.3 % depending on the crack size at the same crack position. Moreover, the maximum difference was 34.8 % according to the crack position when the crack sizes are identical. As jet flow impacts on the obstacle and changes its direction, the recirculation flows are formed. These results are expected to provide useful data to optimize the location and number of gas detections in confined spaces, such as underground CCPP.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.4
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• pp.619-624
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• 2016

Chlorine dioxide ($ClO_2$) gas treatment (75 ppmv, 30 min) has been suggested to improve the microbial safety of postharvest paprika in a previous study. Based on these results, in this study, an additional combined treatment using low-concentration $ClO_2$ gas-generating sticks (3 ppmv) in paprika samples during storage was carried out at $8^{\circ}C$ and 90% relative humidity to further enhance the quality and reduce the decay rate of paprika for the purpose of lengthy storage. After the combined treatment, the initial populations of total aerobic bacteria as well as yeast and molds in the paprika samples decreased by 3.04 and 2.70 log CFU/g, respectively, compared with those of the control samples, and this microbial inactivation was maintained by the low-concentration $ClO_2$ gas-generating sticks during storage. In particular, the decay rate of samples with combined treatment was significantly lower than that of the control. Vitamin C content, hardness, and color quality parameters of paprika samples were not altered by treatment, while weight loss of the samples treated with the combined $ClO_2$ gas was lower than that of the control during storage. These results indicate that the combination of two different $ClO_2$ gas treatments is effective for retaining the quality of paprika during prolonged storage.

• Agricultural and Biosystems Engineering
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• v.2 no.1
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• pp.31-36
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• 2001

Based on the viscous flow characteristics of gas through capillary tube, a simple and cheap gas mixing system was developed for controlling gas compositions in CA chambers. The gas flow rate through capillary tube had a linear relationship with pressure, (length)$^{-1}$ and (radius)$^4$ of capillary tube, which agreed well with Hagen-Poiseuille’s law. The relationship between flow rate and combined parameters was described as Q=0.000209724($\pi$ r$^4$P/$\mu$L) and the coefficient of determination was 0.9984. The developed system could control gas concentrations in CA chambers within $\pm$0.3% deviation compared to the preset concentrations. It was possible to predict the required time and required gas flow rate for exchanging the gs in CA chamber to a certain concentration of gas by using the mathematical model developed in this study.