• Journal of Ecology and Environment
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• v.33 no.3
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• pp.261-270
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• 2010

Increasing atmospheric $CO_2$ affects the soil carbon cycle by influencing microbial activity and the carbon pool. In this study, the effects of elevated $CO_2$ on extracellular enzyme activities (EEA; ${\beta}$-glucosidase, N-acetylglucosaminidase, aminopeptidase) in salt marsh sediment vegetated with Suaeda japonica were assessed under ambient atmospheric $CO_2$ concentration (380 ppm) or elevated $CO_2$ concentration (760 ppm) conditions. Additionally, the community structure of sulfate-reducing bacteria (SRB) was analyzed via terminal restriction fragments length polymorphism (T-RFLP). Sediment with S. japonica samples were collected from the Hwangsando intertidal flat in May 2005, and placed in small pots (diameter 6 cm, height 10 cm). The pots were incubated for 60 days in a growth chamber under two different $CO_2$ concentration conditions. Sediment samples for all measurements were subdivided into two parts: surface (0-2 cm) and rhizome (4-6 cm) soils. No significant differences were detected in EEA with different $CO_2$ treatments in the surface and rhizome soils. However, the ratio of ${\beta}$-glucosidase activity to N-acetylglucosaminidase activity in rhizome soil was significantly lower (P < 0.01) at 760 ppm $CO_2$ than at 380 ppm $CO_2$, thereby suggesting that the contribution of fungi to the decomposition of soil organic matter might in some cases prove larger than that of bacteria. Community structures of SRB were separated according to different $CO_2$ treatments, suggesting that elevated $CO_2$ may affect the carbon and sulfur cycle in salt marshes.

• The Korean Journal of Physiology
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• v.1 no.2
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• pp.185-191
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• 1967

In order to evaluate the elimination of CO through the lung comparing with the decrease of CO content in the blood, authors had induced acute CO poisoning on 9 dogs. Arterial CO-Hb saturation, CO concentration, %, in expired gas and eliminated CO amount through the lung were measured at 1,5,10,30,60, and 120 minutes after acute CO poisoning in 6 dogs breathing room air and 3 dogs breathing room air and oxygen alternately. Results obtained are summarized as follows. In room air breathing group, arterial CO-Hb saturation averaged 50.8% , and 53.67 ml of CO was blew off through the lung during 120 minutes and in alternately air and oBygen breathing group, the arterial CO-Hb saturation averaged 65.6% and 95.6 ml of CO was blew off through the lung. The amount of CO eliminated in expired gas for 120 minute was much less than the amount of decreased CO in arterial blood which was calculated with the decreased CO-Hb content in the estimated circulating blood volume. Such difference between the amount of eliminated CO in expired gas and the decreased CO in blood might be attributed to the oxidation of CO to $CO_2$ in the tissues. Concentration of CO in expired gas was markedly increased and the rate of decrease in arterial CO-Hb saturation is enhanced by oxygen breathing. In early period of recovery from acute CO poisoning, neither the CO concentration in expired gas, nor, the rate of CO elimination (unlit 2 minutes after CO poisoning) showed close correlation with the blood CO-Hb saturation level. The reason seemed to be due to irregularly depressed or unevenly stimulated respiration which were induced by acute CO poisoning.

• 한국연소학회:학술대회논문집
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• 2000.12a
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• pp.168-174
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• 2000

A diode laser sensor system based on absorption spectroscopy techniques has been developed to measure $CO_2$ concentration and temperature non-intrusively in high temperature combustion environments using a 2.0 ${\mu}m$ DFB(Distributed Feedback) laser. Two optics was fabricated in pig-tail fashion and all optical components were implemented in a single box. The evolution of measurement sensitivity was done using test cell by changing sweep frequency and $CO_2$ concentration. Gas temperature was determined from the ratio of integrated line strengths. Species concentration was determined from the integrated line intensity and the measured temperature. The result show that the system has 2% error in wide operation frequency range and accuracy of $CO_2$ concentration was about 3%. The system was applied to measure temperature and concentration in the combustion region of a premixed $CH_4$ +air triangular flame. The measurement results of gas temperature agreed well with thermocouple results. Many considerations were taken into account to reduce optical noise, etalon effect, beam steering and base line matching problem. The evaluations results and actual combustion measurement demonstrate the practical and applicability for in-situ and real time combustion monitoring in a practical system.

• Journal of Sensor Science and Technology
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• v.23 no.3
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• pp.170-172
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• 2014

$CO_2$ sensor was used only one solid electrolyte in many cases. To improve the sensing characteristics of $CO_2$ sensors, solid electrolyte $CO_2$ sensor has been developed by bi-electrolyte type sensor using Na-Beta-alumina and YSZ. However, in many further studies, bi-electrolyte type sensor was made by pellet pressed by press machine and additional treatment for formation of interface. In the aspect of mass production, using thick film and additional treatment is not suitable. In this study, $CO_2$ sensor was fabricated by bi-electrolyte structure which was made by an NBA paste layer deposited on YSZ pellet and fired at $1650^{\circ}C$ for 2 hour. The formation of stable interface between YSZ and NBA were confirmed by SEM image. When the type IV electrochemical cell arrangement represented by $CO_2,O_2,Pt{\mid}Li_2CO_3-CaCO_3{\parallel}NBA{\parallel}YSZ{\mid}O_2,Pt$ is used to measure the $CO_2$ concentration in air. This sensor EMF should depend only on the concentration of $CO_2$ by logarithmic. Also, sensor shows $P_{CO_2}$ and EMF relationship like nerstian reaction at a temperature of $450^{\circ}C$.

• Horticultural Science & Technology
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• v.30 no.5
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• pp.501-508
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• 2012

Reducing carbon dioxide ($CO_2$) exhaust has become a major issue for society in the last few years, especially since the initial release of the Kyoto Protocol in 1997 that strictly limited the emissions of greenhouse gas for each country. One of the primary sectors affecting the levels of atmospheric greenhouse gases is agriculture where $CO_2$ is not only consumed by plants but also produced from various types of soil and agricultural ecosystems including greenhouses. In greenhouse cultivation, $CO_2$ concentration plays an essential role in the photosynthesis process of crops. Optimum control of greenhouse $CO_2$ enrichment based on accurate monitoring of the added $CO_2$ can improve profitability through efficient crop production and reduce environmental impact, compared to traditional management practices. In this study, a sensor-based control system that could estimate the required $CO_2$ concentration considering emission from soil for cucumber greenhouses was developed and evaluated. The relative profitability index (RPI) was defined by the ratio of growth rate to supplied $CO_2$. RPI for a greenhouse controlled at lower set point of $CO_2$ concentration (500 ${\mu}mol{\cdot}mol^{-1}$) was greater than that of greenhouse at higher set point (800 ${\mu}mol{\cdot}mol^{-1}$). Evaluation tests to optimize $CO_2$ enrichment concluded that the developed control system would be applicable not only to minimize over-exhaust of $CO_2$ but also to maintain the crop profitability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.155-159
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• 2003

Polycrystalline $Ti_{1-x}Co_xO_2$ thin films on $SiO_2$ (200 nm)/Si (100) substrates were prepared using liquid-delivery metalorganic chemical vapor deposition. Microstructures and ferromagnetic properties were investigated as a function of doped Co concentration. Ferromagnetic behaviors of polycrystalline films were observed at room temperature, and the magnetic and structural properties strongly depended on the Co distribution, which varied widely with doped Co concentration. The annealed $Ti_{1-x}Co_xO_2$ thin films with $x{\leq}0.05$ showed a homogeneous structure without any clusters, and pure ferromagnetic properties of thin films are only attributed to the $Ti_{1-x}Co_xO_2$ (TCO) phases. On the other hand, in case of thin films above x=0.05, Co clusters formed in a homogeneous $Ti_{1-x}Co_xO_2$ Phase, and the overall ferromagnetic (FM) properties depended on both $FM_{TCO}$ and $FM_{Co}$. Co clusters with about 10nm-150nm size decreased the value of Mr (the remanent magnetization) and increased the saturation magnetic field.

• Journal of Practical Agriculture & Fisheries Research
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• v.18 no.1
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• pp.71-78
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• 2016

The present study was performed to examine the high temperature adaptability with CO₂ treatment for tomato under the condition of greenhouse cultivation during summer season. The plants with the CO₂ concentration of 1000 ppm recorded higher scores in Fm/Fo and Fv/Fm but lower score in Fo than others through the measurement of chlorophyll fluorescence, which implicated that the plants with the CO₂ concentration of 1000 ppm had more adaptability to high temperature than the others. At the condition of the same air temperature as 30℃ and 40℃, the photosynthetic rate was increased with the increase of CO₂ concentration. When in the high air temperature state of 40℃, although the photosynthic rate was low in comparison with 30℃, its value was about 18.5umolm^-2s^-1 in case of 1000ppm. The higher concentration of CO₂ made the more activated anti-oxidation enzyme (superoxide dismutase and peroxidase) for the both cultivars as 'momotaro' and 'minichal'. The cultivar of 'minichal' performed the high temperature limit as 41℃ at the CO₂ condition of 500 ppm and 43℃ at the CO₂ condition of 1000 ppm through the estimation on the variation of chlorophyll fluorescence Fo by CO₂ concentrations.

• Korean Journal of Plant Resources
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• v.11 no.2
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• pp.119-123
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• 1998

Effects of elevated CO2 and temperature on nitrogen (N) uptake , leaf N concentration, N partitioning , N use efficiency (NUE) and grain yield of pot and field grown rice (Oryza sativa. L.cv. Chukwangbyeo) under canopy-like conditions were studied over three years. Rice plants were grown in pots and in the field in temperature gradient chambers containing either ambient(350ppm) or elevated CO2 concentrations (690 or 650ppm) in conbination with either four or seven temperature regimes ranging form ambient temperature(AT) to AT plus 3$^{\circ}C$. There were three N supplies 94g or 6g m-2 to 20g or 48g m-2.Elevated CO2 increased N uptake in field-grown rice ; the magnitude of this effect was thelargest (+15%) at the highest N level. However, in pot-grown rice, N uptake was suppressed with the effect was the largest at high N levels. Leaf N concentration declined at elevated CO2 mainly due to a decrease in N partitiioning to the leaf blades. Air temperature had little effect on the N parameters mentioned previously, wherease NUE for spikelet production declined rapidly with increased temperature irrespective of CO2 concentration. The response of the biomass to elevated CO2 varied with N level, with the greatest response at 20g N m-2 (+30%) . At AT, where high temperature-induced sterility was generally not observed, elevated CO2 increased yield. However, the magnitude of this effect varied greatly (2-39%) with N level, and was mainly dependent on the magnitude of the increase in spikelet number.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.7
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• pp.35-44
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• 2004

In this study, a ventilation model was developed to determine a ventilation rate for the balance of heat, moisture and $CO_{2}$ in a mushroom house. Internal and external temperature, relative humidity and $CO_{2}$ concentration were measured and used to validate the ventilation model. The effects of various environmental factors on physiological responses of mushroom were also investigated. The verified model was simulated under the observed ventilation rates with a difference of$ 0.001{\~}0.065\;m^{3}{\cdot}S^{-1}$ (relative error of $0.3{\~}18.9\%$) when external temperature varied 22.5 to $24.8^{circ}C$ and average ventilation rates was $0.35m^{3}{\cdot}S^{-1}$. The optimal conditions for mushroom growth (internal temperature $22 ^{circ}C$, relative humidity $80\%$, $CO_{2}$ concentration 1,000 ppm) were used for the model application with external temperature, relative humidity and $CO_{2}$ concentration of $27.5{\~}33.5^{circ}C$, $60\%$, and 355 ppm, respectively. Thermal balance was a important factor for an optimum ventilation up to the external temperature of $32^{circ}C$, while $CO_{2}$ concentration balance was more important over $32^{circ}C$. This suggests that humidification for moisture balance is required to maintain temperature and $CO_{2}$ concentration at an optimal level by ventilation in a mushroom house.

• Journal of the Korean Institute of Educational Facilities
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• v.25 no.4
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• pp.19-30
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• 2018

The school classroom is a common living place where students spend 7 to 14 hours a day to prepare for their careers. Therefore, if the ventilation of the classroom is not properly performed, it may lead to the deterioration of learning ability due to the unclear air. The concentration of carbon dioxide in the classroom is reported to be high, and the increase in carbon dioxide concentration has a negative effect on the learner's academic performance. In this context, the purpose of this study is to propose a methodology for intelligent and responsive window opening-closing operation process that can reduce the concentration of $CO_2$ in the classroom in order to build a support space that can create an effective teaching-learning environment for adolescents. The specific objectives are as follows. First of all, we define the concept of window opening-closing operation. Secondly, twe develop the operation process of window opening-closing. Thirdly, we develop an algorithm for real-time window opening and closing (process) (Window Opening-Closing Operation Process). Finally, we verify the intelligent responsive window opening-closing operation process through developing examples of window opening-closing operation process using the parametric design program. This study is a preliminary study to develop algorithms necessary for window opening-closing operation. Based on the first-order algorithm, We simulated window opening-closing operations according to a hypothetical scenario. As a result, This study can show that the window is open and close depending on the $CO_2$ concentration, but the $CO_2$ concentration in the room is higher than outdoors. Consequentially, we suggest that it is necessary to develop an algorithm to supplement these results because window is often not working when the temperature difference between indoor and outdoor in winter is large.