• Fire Science and Engineering
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• v.28 no.3
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• pp.1-9
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• 2014

In this study, it was developed to the design program optimization the design factors of the carbon dioxide fire extinguishing system on the basis of design theory for the carbon dioxide fire extinguishing system, national emergency management agency (NEMA) notice No. 2012-11, KS B 6261 and steepest descent method of optimization. The design program was developed to C++ compiler based on established the logic and algorithms and was to operate on the Windows operating system. The optimization of design factors for the carbon dioxide fire extinguishing system are minimized subject to constraint on agent flow rate, emission time and design variables (pipe size etc.). It was verified to the design program performance for test system, and it was provided to the foundation for optimal design in fire fighting field. Also, it is considered to improve the efficiency of the fire extinguishing system and to maximize of fire suppression as the construction of the carbon dioxide extinguishing system based on the optimal design factors.

• Journal of Environmental Health Sciences
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• v.41 no.6
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• pp.389-396
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• 2015

Objectives: A hospital is a complex building that serves many different purposes. It has a major impact on patient's well-being as well as on the work efficiency of the hospital staff. Thermal comfort is one of the major factors in indoor comfort. The purpose of this study was to determine thermal comfort in various locations in a hospital. Methods: Various indoor environmental conditions in a general hospital were measured in February 2014. The predicted mean vote (PMV) and carbon dioxide ($CO_2$) concentration were measured simultaneously in the lobby, office, restaurant, and ward. Results: The ward was the most thermally comfortable location (PMV=0.44) and the lobby was the most uncomfortable (PMV = -1.39). However, the $CO_2$ concentration was the highest in the ward (896 ppm) and the lowest in the lobby (572 ppm). The average PMV value was the most comfortable in the ward and the lowest in the lobby. In contrast, for concentration of carbon dioxide, the highest average was in the ward and the lowest in the lobby. Due to air conditioner operation, during operating hours the PMV showed values close to 0 compared to the non-operating time. Correlation between PMV and $CO_2$ differed by location. Conclusion: The PMV and concentration of carbon dioxide of the hospital lobby, office, restaurant and ward varied. The relationship between PMV and carbon dioxide differed by location. Consideration of how to apply PMV and carbon dioxide is needed when evaluating indoor comfort.

• Fire Science and Engineering
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• v.29 no.4
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• pp.26-32
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• 2015

Carbon dioxide principally extinguishes fires by smothering, but an acceptable amount of extinguishing agent is needed. To assure the performance of carbon dioxide systems in Korea, computer programs certified by NEMA are being applied in system design. But the design errors can occur because the geometry of a model test facility is not the same as that of the actual fire area. Since the discharge rate tends to vary considerably with the flow pattern in a pipe, an on-site discharge test is necessary to ensure the performance of the system, especially with low pressure carbon dioxide. Technical standards for carbon dioxide systems do not give detailed guidelines for discharge tests at present. Based on comparative analysis of standards and practical tests, this paper suggests a methodology for on-site discharge tests.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.129-136
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• 2012

In this century, scientists realized that carbon dioxide gas in the atmosphere cause a greenhouse effect which affects the planet's temperature. Therefore lots of attempts have carried out to decrease the discharge of carbon dioxide gas in the field. The dissolved carbon dioxide flotation (DCF) process was developed as an alternative of DAF process to decrease the discharge and reuse of carbon dioxide as well as to save energy consumption. To investigate the particle separation characteristics and the flotation efficiency of carbon dioxide, SCC model was employed in the DCF process which has been applied extensively for the evaluation and simulation in the DAF process. The simulation results by the SCC model revealed the predicted curve of flotation efficiency became decreased gradually over the optimal pressure range of saturator about 1.6 atm in accordance with the experiment results of the DCF pilot plant and the size distribution and the bubble volume concentration of $CO_{2}$ bubbles depending on the operation pressure of saturator. The findings through the simulation results led to the conclusion that there was no significant difference between $CO_{2}$ bubbles and air bubbles, affecting on the practical flotation efficiency, in terms of the initial collision and attachment efficiency.

• Journal of Sensor Science and Technology
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• v.26 no.3
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• pp.179-185
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• 2017

This article describes the characteristics of nondispersive infrared carbon dioxide gas sensor according to the temperatures and humidifies. In this researches, a thermopile sensor that included application-specific integrated circuit (ASIC) was used and the White-cell structure was implemented as an optical waveguide. The developed sensor modules were installed in gas chamber and then the temperature of gas chamber has been increased from 283 K to 313 K with 10K temperature step. In order to analyze the effects of humidity levels, the relative humidity levels were changed from 30 to 80%R.H. with small humidifier. Then, the characteristics of sensor modules were acquired with the increment of carbon dioxide concentrations from 0 to 2,000 ppm. When the initial voltages of sensors were compared before and after humidifying the chamber at constant temperature, the decrements of the output voltages of sensors are like these: 9mV (reference infrared sensor), 41 mV (carbon dioxide sensor), 2 mV (temperature sensor). With the increment of ambient temperature, the averaged output voltage of carbon dioxide sensor was increased 19 mV, however, when the humidity level was increased, it was decreased 14mV. Based upon the experimental results, the humidity effect could be alleviated by the increment of temperature, so the effects of humidity and temperature could be only compensated by the ambient temperature itself. The estimated carbon dioxide concentrations showed 10% large errors below 200 ppm, however, the errors of the estimations of carbon dioxide concentrations were less than ${\pm}5%$ from 400 to 2,000 ppm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6590-6596
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• 2013

Carbon dioxide should be removed to increase the productivity of dimethyl ether(DME) from the DME manufacturing process. In this study, carbon dioxide can be removed using a physical absorbent through a solvent absorption method and membrane separation method. After performing the simulation for the carbon dioxide removal process, the energy consumption of the processes was compared. Methanol was used as a physical absorbent for the rectisol process, dimethyl ethers of polyethylene glycol for the Selexol process and N-methyl pyrrolidone for the Purisol process. By performing the simulation for each process, the energy consumption was compared. The Purisol process had the lowest energy consumption, followed in order by the Selexol process, Rectisol process and Membrane process. Therefore, the Purisol process was the most suitable method for the carbon dioxide process in the DME manufacturing process.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.10
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• pp.673-679
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• 2016

Because of the growing interest in supercritical carbon dioxide power cycle technology owing to its potential enhancement in compactness and efficiency, supercritical carbon dioxide cycles have been studied in the fields of nuclear power, concentrated solar power (CSP), and fossil fuel power generation. This study introduces the current status of the research project on the supercritical carbon dioxide power cycle by Korea Institute of Energy Research (KIER). During the first phase of the project, the un-recuperated supercritical Brayton cycle test loop was built and tested. In phase two, researchers are designing and building a supercritical carbon dioxide dual Brayton cycle, which utilizes two turbines and two recuperators. Under the simulation condition considered in this study, it was confirmed that the design parameter has an optimal value for maximizing the net power in the supercritical carbon dioxide dual cycle.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.128-134
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• 2012

The pilot scale experiments can handle the flue gas up to 1,000 $Nm^3/hr$ for separation of carbon dioxide included in real flue gas at coal-fired power plant. The operational characteristics was analyzed with the main experimental variables such as flue gas flow rate, absorbent circulation rate using chemical absorbents mono-ethanolamine( MEA) and 2-amino-2-methyl-1-propanol(AMP). The more flue gas flow rate decreased in 100 $m^3/hr$ in the MEA 20 wt% experiments, the more carbon dioxide removal efficiency was increased 6.7% on average. Carbon dioxide removal efficiency was increased approximately 2.8% according to raise of the 1,000 kg/hr absorbent circulation rate. It also was more than 90% at $110^{\circ}C$ of re-boiler temperature. Carbon dioxide removal efficiency of the MEA was higher than that of the AMP. In the MEA(20 wt%) experiment, carbon dioxide removal efficiency(85.5%) was 10% higher than result(75.5%) of ASPEN plus simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4635-4642
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• 2013

The advanced absorbent that used amine mixture with different order were developed to separate carbon dioxide emitted from fossil fuel power plant. The carbon dioxide absorption capacity for mixtures with different amine(primary, secondary and tertiary) were investigated according to $CO_2$ partial pressure. The carbon dioxide absorption capacity at the same pressure is ordered as 3DMA1P 30wt%>3DMA1P 27wt%+MEA 3wt%>3DMA1P 27wt%+DEA 3wt%. The result indicates that mixing tertiary amine with primary amine yields more efficient carbon dioxide absorbent than mixing tertiary with secondary amine does. Finally, the predicted semi-empirical gas-liquid equilibrium model fitted with experimental results.

• Membrane Journal
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• v.16 no.4
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• pp.252-258
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• 2006

A numerical analysis was performed for a separation process of carbon dioxide from a flue gas stream using polyethersulfone hollow fiber membranes. Countercurrent flow governing equations were regarded to be two point boundary-value problem and the nonlinear ordinary differential equation were simultaneously solved using the finite- difference method. A computer program was developed using the Compaq Visual Fortran 6.6 software. The carbon dioxide permeate driving force and the fred gas residence time at the inside of membrane were found to be very important factors affecting the permeation characteristics of carbon dioxide. The carbon dioxide concentration in the permeate and the flow rate of the permeate were found to be slightly larger by a few percent with a countercurrent flow analysis than those with a cocurrent flow analysis.