• Journal of Korean Society of Environmental Engineers
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• 제31권7호
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• pp.505-514
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• 2009

Aqueous potassium salt of serine was proposed as an alternative $CO_2$ absorbent to monoethanolamine (MEA) and its $CO_2$ absorption characteristics were studied. The experiment has been conducted using screening test equipment with NDIR type gas analyzer and vapor-liquid equilibrium apparatus. $CO_2$ absorption/desorption rate and net amount of $CO_2$ absorbed in cyclic process are the criteria to assess the $CO_2$ absorption characteristics in this study. Effective $CO_2$ loading of potassium salt of serine and MEA are 0.425 and 0.230 respectively. Cyclic capacities are 0.354 and 0.298 for potassium salt of serine and MEA. The absorption rate of the potassium serinate decreased sharply at $CO_2$ loading is 0.1 and were maintained approximately at half of MEA. To enhance the absorption rate of aqueous potassium salt of serine, small quantities of rate promoters, namely piperazine and tetraethylenepentamine were blended, so that rich $CO_2$ loading were increased by 13.7% and 18.7% respectively. The rich $CO_2$ loading of potassium salt of serine was 29.2% and 35.0% higher than those of aqueous sodium and lithium salt of serine, respectively. The absorption rate of potassium salt of valine and isoleucine which have similar molecular structures to serine were lower than that of serine because of the presence of bulky side group. Precipitation phenomena during $CO_2$ absorption were discussed by the aid of literatures.

• Journal of Korean Society of Forest Science
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• 제34권1호
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• pp.63-71
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• 1977

${\times}$Populus albaglandulosa has been needed optimum stand density according to various site and its wood usage. It is assumed that optimum stand density can be estimated by investigating of response of ${\times}$P. albaglandulosa to the light factor of stand. For that reason, the photosynthesis of ${\times}$Populus albaglandulosa grown under the controlled planting density was studied in relation to its leaf age by the aid of the Infrared gas analyzer. Rate of net photosynthesis was smaller in matured leaves than young leaves below $8^{\circ}C$, while, it was larger than young leaves above $8^{\circ}C$. Temperature for the maximum net photosynthesis of young leaves and old leaves was about $30^{\circ}C$ and $25^{\circ}C$ respectively. Saturated light intensity varied slightly as leaf age from 28 Klux to 35 Klux, but net photosynthesis rate in the range of light intensity showed deep differences. Old leaves marked the lowest rate, $1.6\;CO_2\;mg/dm^2/hr$, young leaves marked the medium rate, 1.7 to $2.2\;CO_2\;mg/dm^2/hr$, and matured leaves marked the most efficient photosynthesis, 2.9 to $3.5\;CO_2\;mg/dm^2/hr$. Young leaves of 5 days old had the highest light compensation point, while matured leaves of 35 days-old had the lowest point. Rates of dark respiration in both young leaves and old leaves were higher than that of matured leaves. Trees which were planted at space $80cm{\times}80cm$ showed productive assimilation function over the one-third of height where relative light intensity is 35%.

• Ecology and Resilient Infrastructure
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• 제8권1호
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• pp.32-43
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• 2021

Multichannel automated chamber systems (MCACs) were developed for the continuous monitoring of soil CO2 efflux in forest ecosystems. The MCACs mainly consisted of four modules: eight soil chambers with lids that automatically open and close, an infrared CO2 analyzer equipped with eight multichannel gas samplers, an electronic controller with time-relay circuits, and a programmable logic datalogger. To examine the stability and reliability of the developed MCACs in the field during all seasons with a high temporal resolution, as well as the effects of temperature and soil water content on soil CO2 efflux rates, we continuously measured the soil CO2 efflux rates and micrometeorological factors at the Nam-san experimental site in a Quercus mongolica forest floor using the MCACs from January to December 2010. The diurnal and seasonal variations in soil CO2 efflux rates markedly followed the patterns of changes in temperature factors. During the entire experimental period, the soil CO2 efflux rates were strongly correlated with the temperature at a soil depth of 5 cm (r2 = 0.92) but were weakly correlated with the soil water content (r2 = 0.27). The annual sensitivity of soil CO2 efflux to temperature (Q10) in this forest ranged from 2.23 to 3.0, which was in agreement with other studies on temperate deciduous forests. The annual mean soil CO2 efflux measured by the MCACs was approximately 11.1 g CO2 m-2 day-1. These results indicate that the MCACs can be used for the continuous long-term measurements of soil CO2 efflux in the field and for simultaneously determining the impacts of micrometeorological factors.

• Journal of Food Hygiene and Safety
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• 제39권3호
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• pp.250-259
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• 2024

In this study, we investigated in pesticide residues and heavy metals in fermented liquor products (wine, beer, makgeolli). Targeted analysis of 400 pesticide residues in the sample was performed using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method, followed by gas chromatography-tandem mass spectrometry (MS/MS) and LC-MS/MS. The contents of heavy metals (Pb, Cd) were determined by ICP-MS using the microwave method. The mercury was measured using a mercury analyzer. From the analysis of 150 cases, 102 (68.0%) cases of fermented liquor were detected, and 35 pesticide residues (including metalaxyl, mandipropamid, azoxystrobin, and fenhexamid) were detected among the 400 pesticide residues tested. Pb, Cd, and Hg were tested in 150 samples. Lead was detected in 73 samples (48.7%), cadmium in 9 samples (6.0%), and mercury in 36 samples (24.0%). Exposure assessment was conducted to determine the safety of the detected pesticide residues and heavy metals. According to this assessment, the pesticide residues and heavy metals showed very low %ADI values (less than 1%).