• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.18-25
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• 2013

It may occur health hazards or death by suffocation or acute poisoning in case of oxygen deficiency in ambient or exposure to harmful gas. As a part of accident prevention, we studied the change of activity and lethal dose by changing the concentration of several hazardous gas with inhalation exposure chamber and laboratory animals. We investigated the lethality and motility change during either the 4 hrs whole body exposure to oxygen, nitrogen, toluene, $H_2S$, CO and 48 recovery. As results, it is estimated that 5% oxygen concentration as lethal concentration and 5.5% as $LC_{50}$ (rat, 4 hrs) with statistics for dose-response. The results of lethality in oxygen deficient condition (approximately 6%), the lethalities were 40%, 20% with 20 ppm $H_2S$, 600 ppm CO respectively, and was not increased the lethality with 8% CO. Thus, it was confirmed that the $H_2S$, CO had influence to lethal dose, while toluene had low fluence.

• Journal of Korea Soil Environment Society
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• v.3 no.2
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• pp.41-51
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• 1998

The research was conducted to measure the heavy metal pollution of soils and vegetations adjacent to the closed Daeseong coal mine in Keumsan, Chungnam. The studied area was divided into two sites ; the coal-bearing polluted and the non-polluted without coal. The samples of the weathered soils and vegetations(Miscnthus sinenis(MS) and Pinus rigida(PR)) were collected from both area. Cr, Mo, Ni, and Fe concentrations were high in the polluted soils, whereas Co, Sc, and Zn concentrations were high in the non-polluted soils. In the vegetations, Co, Cr, Sc, and Fe concentrations in the roots of MS and PR growing on the polluted sites were higher than the above-ground. However, on the non-polluted sites, Mo and Ni concentrations had an opposite trend. In the above-ground parts, high heavy metal concentrations (except Cr) were shown in MS of the non-polluted sites, whereas in the roots, heavy metal concentrations (except Zn) were high in the polluted sites. In the average heavy metal concentrations of two plants, most elements (except Zn) were lower in the plants than the soils. Comparing with vegetations and adjacent forest soils, heavy metal concentrations of the MS were similar to those of soil concentrations relative to the PR, suggesting that absorptions of the elements were higher in the MS than the PR.

• Applied Biological Chemistry
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• v.19 no.2
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• pp.93-98
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• 1976

The experiment was made to investigate concentrations of $CO_2\;and\;O_2$ in the removal of astringency of persimmon fruits and to study the changes of total, reducing sugar and hardness during the removal of astringency. 1. During the removal of astringency of persimmon fruits, channel of tannin content showed the rapid decrease in high concentration of $CO_2$ and the gradual decrease in low concentration of $CO_2$. 2. Concentration of oxygen did not show effect on the removal of astringency at high concentration of $CO_2$ but at low concentration of $CO_2$ in Chungdo-Bansi. 3. Optimal concentration of the removal of astringency was $60{\sim}70%,\;CO_2$ and $6{\sim}8%\;O_2$ in Chungdo-Bansi and Sagoksi 4. In changes of sugar content total sugar was decreased and reducing sugar was increased.

• Food Science and Preservation
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• v.11 no.2
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• pp.246-249
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• 2004

This study was conducted to evaluate the inhibition efficacy of high CO$_2$ atmosphere (35, 60, and 100% ${\times}$ 24, 48, and 72 h) on growth of Botrytis cinerea in vitro in order to offer sterilizing method of horticultural crops including peach fruits. Botrytis cinerea was isolated from a naturally infected peach fruits. Growth of the fungus at 25$^{\circ}C$ declined with increased CO$_2$ concentration and treatment duration. Especially, 100% CO$_2$ provided completely inhibition effect of growth of the fungus for 72 h. After removal of high CO$_2$ condition, however, the fungus showed normal growth speed. The growth of fungus at low temperature was completely inhibited temporarily by short-term 100% CO$_2$ treatment, but resumed right after transferring to normal atmosphere at 25$^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1410-1412
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• 2003

PTC 자기발열기판을 사용해서 저전력 방폭형 CO센서를 제작하고 그 특성을 고찰하였다. CO가스센서의 감지특성을 향상시키기 위하여 Pt가 island 형상을 갖는 다층 Pt/$SnO_2$ 박막구조를 도입하였으며, 이와 같은 구조는 Pt/$SnO_2$ 위에 다시 $SnO_2$ 및 Pt cluster 층들을 연속적으로 증착함으로서 제작되었다. 200ppm의 CO가스농도에서 측정된 다층 $Pt/SnO_2$박막 센서의 감도는 1.72($R_{air}/R_{CO}$)로, 단충 Pt/$SnO_2$ 박막 센서의 최대감도(1.23)보다 훨씬 더 높았다 이것은 Pt와 $SnO_2$사이의 계면적 증대에 기인하는 것으로 생각된다. 제작된 Pt/$SnO_2$ 가스센서의 평균 소비전력은 38.5mW이며, 측정농도범위($30{\sim}1,000ppm$)에서 매우 양호한 감지특성을 나타내었다.

• The Journal of Natural Sciences
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• v.4
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• pp.95-102
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• 1991

The influences of various concentrations of thallium carbonate on the hydration of tricalcium silicate which is widely used to the inorganic materials have been studied using an isothermal microcalorime-ter. The experimental results indicate that the hydration of tricalcium silicate is accelerated in the presence of thallium carbonate, namely the concentration of thallium carbonate is increased, the rate of hydration is also increased. The x-ray diffraction analysis shows that the concentration of tricalcium silicate decreases rapidly in the presence of thallium carbonate. Differential thermal analysis of tricalcium silicate hydrated in the persence of thallium carbonate indicates the presence of calcium carbonate. The nonevaporable water content and the degree of hydration of tricalcium silicate show that the accelerating action of thallium carbonate is more pronounced only during the early period of hydration. Analytical results of the liquid phase in contact with the tricalcium silicate paste indicate that the concentrations of calcium and hydroxyl ions are changed considerably in the presence of thallium carbonate.

• FLOWER RESEARCH JOURNAL
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• v.17 no.1
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• pp.29-35
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• 2009

The study was conducted to examine effective concentration and fertilization time of $CO_2$ for the growth of potted Phalaenopsis in growth chambers. Enrichment level of $CO_2$ was 1,000 or $2,000{\mu}mol{\cdot}mol^{-1}$ and fertilization time was 06:00~12:00, 00:00~06:00, or 18:00~24:00. Two, seven, or twelve month-old clonal micropropagules of Phalaenopsis cultivars were cultured for 99 days. Leaf number, leaf length, leaf width, root length and fresh weight of all Phalaenopsis cultivars in $2,000{\mu}mol{\cdot}mol^{-1}$ $CO_2$ were significantly greater than that of $1,000{\mu}mol{\cdot}mol^{-1}\;CO_2$. $CO_2$ fertilization time was the greatest growth in 0:00~06:00.

• Journal of the Korean Electrochemical Society
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• v.9 no.4
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• pp.141-150
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• 2006

Nanocrystalline CoW thin/thick film alloys were electodeposited from citrate baths to investigate the influences of metal ion concentration, current density and solution pH on chemical composition, current efficiency, residual stress, surface morphology, and microstructure of the film. Deposit W (tungsten) content in CoW thin/thick film increased with increasing W ion concentration, current density, and solution pH in the plating bath. It was observed that residual stress in CoW thin/thick film decreased with increasing W ion concentration and solution pH. CoW thin film exhibited mixed phases of hop Co [(100) and (002)] and hcp $Co_3W$ [(002) and (201)] at W ion concentration with 0.02 to 0.08 M. The microstructure of CoW thin film at W ion concentration of 0.1 to 0.2 M was close to amorphous phase. The dominant phases were found to be hop Co (002) and hop $Co_3W$ [(200), (002) and (201)] at the current densities of 5, 10, 25, and $100mA{\cdot}cm^{-2}$ CoW thin film at the current densities of 50 and $75mA{\cdot}cm^{-2}$ was close to amorphous phase. At solution pH 8.7, CoW thin film exhibited hcp Co (002) and hop $Co_3W$ [(200), (002) and (201)]. Below solution pH 8.7, CoW thin film exhibited amorphous microstructure. The optimum electrodeposition conditions for CoW thin/thick film were found to be W ion concentration of 0.08 M, current density of $10mA{\cdot}cm^{-2}$, and solution pH 8.7.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2007.10a
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• pp.265-267
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• 2007

• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.17-22
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• 2013

In this study, a pH control method by carbon dioxide ($CO_2$) was applied to coagulation process in water treatment plant (WTP) to investigate the coagulation efficiency and residual dissolved aluminum when high pH raw water is flowing into the plant during algal blooming. Existing coagulant dose (1 mg/L in raw water) resulted in the pH reduction of 0.0384 by LAS, 0.0254 by PAC, 0.0201 by A-PAC, and 0.0135 by PACS2, respectively. And then the concentration of dissolved aluminum was 0.02 mg/L at pH 7.44, 0.07 mg/L at pH 7.96, 0.12 mg/L at pH 8.16, 0.39 mg/L at pH 8.38 showing the concentration increase with pH in the coagulation process. It was noteworthy that rapid increase was observed at pH above 8.0 next the rapid mixing. Therefore it is necessarily required to control pH below 7.8 in the coagulation process in order to meet drinking water quality standard of aluminum for high pH raw water into WTP, $CO_2$ injection could control pH successfully at about 7.3 even for the raw water of high pH above 8.0. In addition it was found that the pH control by $CO_2$ injection was significantly effective for coagulation in terms of turbidity removal, coagulant dosage, and residual dissolved aluminum concentration.