• 통합자연과학논문집
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• 제7권2호
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• pp.120-123
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• 2014

When a hydrophobic and hydrophilic environments of bis(2,2'-bipyridyl) copper(II) ($Cu(bpy)_2{^{2+}}$) are produced in the presence of anionic surfactant sodium dodecyl sulfate (SDS), cyclic voltammetry is used to investigate the microscopic environments which occurs at the glassy carbon electrode. In order to see the relation between ${\Delta}E_p$ and a critical micelle concentration (CMC), ${\Delta}E_p$ vs. -Log[SDS] for the redox couples are plotted. The concentration at the intersection of two lines is 2.57 mM SDS, and this concentration can be determined as the CMC (relative error: below 0.03%; 2.63 mM SDS by surface tensiometry).

• 제어로봇시스템학회논문지
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• 제8권5호
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• pp.407-412
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• 2002

A measurement device for gas concentration and flow rate using hot wire is developed for the utilization in industrial applications. The device has two cells of measuring and reference, and a bridge circuit is installed to detect electric current through the hot wire in the cells. An amplification of the signal and conversion to digital output are conducted for the on-line measurement with a personal computer. The flow rate of air and carbon dioxide gas is separately measured for the performance examination of the device. Also, the concentration of air-carbon dioxide and carbon dioxide-argon mixtures is determined for the same evaluation. The outcome of the performance test indicates that the accuracy and stability of the device is satisfactory for the purpose of industrial applications.

• 한국습지학회지
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• 제21권4호
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• pp.257-266
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• 2019

본 연구에서는 함평만에 속하는 무안 지역의 갯벌에서 갈대가 서식하는 식생 지역과 갈대가 없는 비식생 지역을 6개 지점씩 선정하여 저조시에 계절별로 이산화탄소 농도와 플럭스 및 지온의 변화를 관측하였다. 관측은 2012년 5월 30일(봄)과 8월 8일(여름), 2013년 1월 31일(겨울)에 각각 수행되었다. 관측 결과, 식생 지역의 이산화탄소 평균농도는 전체적으로 겨울에 가장 높았고 봄, 여름 순으로 나타났으며, 비식생 지역도 식생 지역과 같은 농도변화를 보였다. 식생 지역의 이산화탄소 플럭스는 봄과 여름에 모두 양(+)의 값으로 방출(emission)의 형태를 보이나, 겨울에는 반대로 흡수(uptake)하는 음(-)의 값으로 나타났다. 이산화탄소 플럭스의 평균값은 봄이 가장 높았으나 여름과 거의 유사하였고, 겨울은 낮은 음의 값으로 나타났다. 비식생 지역은 봄에 양의 값으로 방출의 형태를 보였고, 여름과 겨울에는 흡수하는 음의 값으로 나타났다. 평균값은 봄이 가장 높았고, 여름과 겨울의 차는 작게 나타났다. 연구지역 이산화탄소 플럭스의 계절적인 변화특성은 봄의 경우 식생과 비식생 지역 모두 호흡에 의한 방출이 우세하였으며, 여름은 식생 지역에서 방출이 우세하였고 비식생 지역은 식물플랑크톤의 광합성에 의한 흡수가 확인되었으나 매우 미미하였다. 겨울은 식생 지역에서 이산화탄소 플럭스의 변화가 거의 나타나지 않았으며, 비식생 지역은 흡수가 일부 확인되었으나 매우 미미하였다.

• Carbon letters
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• 제9권4호
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• pp.275-282
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• 2008

Chemically activated carbons were prepared from maize cobs, using phosphoric acid of variable concentration. The textural parameters of the activated carbons were determined from the nitrogen adsorption isotherms measured at 77 K. The chemistry of the carbon surface was determined by measuring the surface pH, the pHPZC and the concentration of the carbon - oxygen groups of the acid type on the carbon surface. Kinetics of Cr(VI) sorption/reduction was investigated at 303 K. Two processes were investigated in terms of kinetics and equilibrium namely; Cr(VI) removal and chromium sorption were studied at various initial pH (1-7). Removal of Cr(VI) shows a maximum at pH 2.5. At pH<2.5, sorption decreases because of the proton competition with evolved Cr(III) for ion exchange sites. The decrease of sorption at pH>2.5 is due to proton insufficiency and to the decrease of the extent of Cr(VI) reduction. The chemistry of the surface of activated carbon is an important factor in determining its adsorption capacity from aqueous solutions particularly when the sorption process involves ion exchange.

• The Korean Journal of Ecology
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• 제27권2호
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• pp.67-71
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• 2004

This study was carried out to evaluate soil carbon and nutrient storage of three adjacent coniferous plantations (Larix leptolepis, Pinus densiflora and Pinus rigitaeda) growing on a similar site with a same planting age (42-year old) in the Sambong Exhibition Forests, Hamyang-gun, Gyungsangnam-do. The soil carbon concentration among three plantations was not significantly different in 0∼10cm soil depth, but other two depths (10∼20cm and 20∼30cm) showed higher carbon concentration in P. densiflora plantation than the other two plantations. The exchangeable cation concentrations (Ca and Mg) in 0∼10cm depth were significantly lower in L. leptolepis plantation than in the other two plantations, while nitrogen and phosphorus concentrations were not significantly different among three plantations except for nitrogen at 10∼20cm depth in P. rigitaeda plantation. Soil carbon storage in 0∼20cm depth of three plantations was unaffected by the stand types. Soil nutrient storage was not significantly different at each depth except for nitrogen storage at 10∼20cm depth in P. rigitaeda plantation because of the variation of bulk density and coarse fragment. This result demonstrates that soil carbon and nutrient concentrations among the plantations on a similar soil condition can be altered significantly by tree species effects over 40 years after plantation establishment.

• Carbon letters
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• 제8권2호
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• pp.101-107
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• 2007

Activated carbons were prepared by impregnation of crushed clean date pits in concentrated solutions of phosphoric acid or zinc chloride followed by carbonization in absence of air at $600^{\circ}C$. Steam-activated carbon was prepared by gasifying $600^{\circ}C$-carbonization product at $950^{\circ}C$ to a burn-off = 50%. KOH- activated carbon was prepared by impregnating date pitscarbonization product obtained at $450^{\circ}C$ in concentrated KOH solution followed by carbonization at $840^{\circ}C$. Textural properties of these carbons were determined from nitrogen adsorption at $-196^{\circ}C$ and the chemistry of the carbon surface was investigated by determination and of the surface carbon-oxygen (C-O) groups using bases of variable strength and dilute HCl. The adsorption of endosulphan at $27^{\circ}C$ on all the carbons prepared was undertaken. Adsorption of this pesticide at 32 and $37^{\circ}C$ was also undertaken for steam-activated and KOH-activated carbons. Phosphoric acid-activated carbons and steamactivated carbons are mainly microporous and have high surface concentration of C-O groups of acidic nature. Steamactivated and KOH-activated carbons exhibited surface areas > 1000 $m^2/g$ and contain micro and non-micrpores. The adsorption of endosulphan was related to the surface area of non-micropores and was retarded by the high concentration of surface C-O groups. The thermodynamic properties indicated the feasibility of the adsorption process and the possible regeneration of the carbon for further use.

• 한국지반환경공학회 논문집
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• 제25권3호
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• pp.5-11
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• 2024

이산화탄소 포집 및 지중 저장을 위해 유망한 지질학적 구조로는 대수층, 폐유전 및 가스전 등이 존재한다. 이 중 대수층은 다른 지질학적 구조에 비해 많은 양의 이산화탄소 저장이 가능한 것으로 판단됨에 따라 그 관심이 증가하고 있으며, 대수층의 특성을 반영하여 이산화탄소 저장 효율 향상을 위한 기술 개발이 필요한 실정이다. 따라서, 본 연구에서는 음이온성 계면활성제를 활용하여 공극수가 존재하는 마이크로모델 내 계면활성제 선 주입 후 초임계 이산화탄소 후속 주입에 따른 이산화탄소 저장 효율 평가를 수행하였다. 그 결과 선 주입되는 계면활성제 수용액의 농도가 증가함에 따라 이산화탄소 저장 효율이 개선되며, 농도가 낮을수록 이산화탄소 저장 효율 개선을 위한 더 많은 계면활성제의 주입이 필요한 것으로 나타난다. 또한 동일한 계면활성제 농도 조건에서 선행 연구의 계면활성제-초임계 이산화탄소 치환보다 계면활성제 선 주입 방식에서 이산화탄소 저장 효율은 약 30% 낮은 값을 나타내며, 본 연구의 최대 농도 조건에서 선행 연구와 유사한 이산화탄소 저장 효율을 나타낸다. 이러한 결과는 향후 대수층 내 이산화탄소 저장 효율 향상을 위한 계면활성제 적용 시 농도 결정에 활용될 것으로 기대된다.

• 한국환경보건학회지
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• 제23권2호
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• pp.57-63
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• 1997

This study was carried out to find the adverse health effects of ozone by papers, the potential indoor sources of ozone by papers, and then the removal mechanism of ozone by experiments. The exposure of individuals to excessive levels of ozone both in the industrial and ambient environment is a continuing public health concern. Ozone indoors may play a role in generating secondary pollutants that may have adverse health effects. The removal efficiency of ozone was studied by (1) the effect of concentration on breakthrough time, (2) the effect of flow rate on breakthrough time, (3) the effect of adsorbent's weight on breakthrough time, (4) the effect of temperature on breakthrough time, (5) the application of Langmuir's isotherm equation in using activated carbon. The followings are the conclusions that were derived from this study. 1. In the effect of concentration on breakthrough time, the adsorption capacity of activated carbon was inversely proportional to ozone concentratuion (0.1, 0.2, 0.3 ppm). 2. In the effect of flow rate on breakthrough time, the service life of activated carbon was inversely proportional to flow rate (2, 8, 14l/min). 3. The difference in removal efficiency of ozone between weights(100 mg and 150 mg) was seen. And when weight of activated carbon was 100 mg and 150 mg, pressure loss was 4-5mmHg and 6-7mmHg, respectively. It is required to study relations among flow rate and adsorbent's weight and ventilation quantity, too. 4. Generally, Langmuir's equation, one of the oldest and most used frequently isotherm equation, applies to chemisorption. In case of ozone, when the weight of activated carbon was 70 mg and temperature 40, slope(1/a) was $6.25\times 10^{-1}$ and intercept(1/ab) was $1.9\times 10^{-4}$ (average r=0.94).

• 대기
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• 제25권1호
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• pp.85-97
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• 2015

This study is to investigate future changes in carbon cycle using the HadGEM2-Carbon Cycle simulations driven by $CO_2$ emissions. For experiment, global carbon budget is integrated from the two (8.5/2.6) representative concentration pathways (RCPs) for the period of 1860~2100 by Hadley Centre Global Environmental Model, version 2, Carbon Cycle (Had-GEM2-CC). From 1985 to 2005, total cumulative $CO_2$ amount of anthropogenic emission prescribed as 156 GtC. The amount matches to the observed estimates (CDIAC) over the same period (136 GtC). As $CO_2$ emissions into the atmosphere increase, the similar increasing tendency is found in the simulated atmospheric $CO_2$ concentration and temperature. Atmospheric $CO_2$ concentration in the simulation is projected to be 430 ppm for RCP 2.6 at the end of the twenty-first century and as high as 931 ppm for RCP 8.5. Simulated global mean temperature is expected to rise by $1.6^{\circ}C$ and $3.5^{\circ}C$ for RCP 2.6 and 8.5, respectively. Land and ocean carbon uptakes also increase in proportion to the $CO_2$ emissions of RCPs. The fractions of the amount of $CO_2$ stored in atmosphere, land, and ocean are different in RCP 8.5 and 2.6. Further study is needed for reducing the simulation uncertainty based on multiple model simulations.

• 한국재료학회지
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• 제33권3호
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• pp.106-114
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• 2023

The carbon concentration in the carburized steels was measured by electron probe microanalysis (EPMA) for a range of soluted carbon content in austenite from 0.1 to 1.2 wt%. This study demonstrates the problems in carbon quantitative analysis using the existing calibration curve derived from pure iron (0.008 wt%C) and graphite (99.98 wt%C) as standard specimens. In order to derive an improved calibration curve, carbon homogenization treatment was performed to produce a uniform Kα intensity in selected standard samples (AISI 8620, AISI 4140, AISI 1065, AISI 52100 steel). The trend of detection intensity was identified according to the analysis condition, such as accelerating voltage (10, 15, 30 keV), and beam current (20, 50 nA). The appropriate analysis conditions (15 keV, 20 nA) were derived. When the carbon concentration depth profile of the carburized specimen was measured for a short carburizing time using the improved calibration curve, it proved to be a more reliable and accurate analysis method compared to the conventional analysis method.