• Journal of Ecology and Environment
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• 제33권3호
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• pp.195-204
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• 2010

In the study, the effects of elevated $CO_2$ and temperature on the photosynthetic characteristics, chlorophyll content, nitrogen content, carbon content, and C/N ratio of Phytolacca insularis and Phytolacca americana were examined under control (ambient $CO_2+$ ambient temperature) and treatment (elevated $CO_2+$ elevated temperature) for 2 years (2008 and 2009). The photosynthetic rate, transpiration rate and water use efficiency of two plant species were higher under the treatment than the under the control. The stomatal conductance of P. insularis was higher under the control, but that of P. americana was not significantly affected by $CO_2$ and temperature under the treatment. The chlorophyll contents of two species were decreased about 72.5% and 20%, respectively, by elevated $CO_2$ and temperature. The nitrogen contents of two species were not significantly altered by increase in $CO_2$ and temperature. The carbon contents of the two species were higher under the treatment than under the control. The C/N ratio of P. insularis was higher under the treatment but that of P. americana was not significantly affected by $CO_2$ and temperature. These results demonstrated that the physiological responses of P. insularis native plants might be more sensitively influenced by a $CO_2$-mediated global warming situation than those of the P. americana invasive plants.

• 열처리공학회지
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• 제15권5호
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• pp.219-227
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• 2002

This study has been performed to investigate the effect of $CO_2$ content on the growth characteristics of the compound layer, porous layer and corrosion characteristics of carbon steels after gaseous nitrocarburizing in $70%-NH_3-CO_2-N_2$ at $580^{\circ}C$ for 2.5 hrs. The results obtained from the experiment were the thickness of the compound and porous layers increased with increasing $CO_2$ contents. At the same fixed gas composition the thickness of the compound and porous layer increased with increasing carbon content of the specimens. X-ray diffraction analysis showed that compound layer was mainly consisted of ${\varepsilon}-Fe_{2-3}(N,C)$ and ${\gamma}^{\prime}-Fe_4N$ as the increased with $CO_2$ contents in atmosphere, compound layer was chiefly consisted of ${\varepsilon}-Fe_{2-3}(N,C)$ phase. With increasing $CO_2$ content and total flow rate in gaseous nitrocarburizing, the amount of ${\varepsilon}-Fe_{2-3}(N,C)$ phase in the compound layer was increased. The current density of passivity decreased with increasing $CO_2$ content due to the development of porous layer at the out most surface of ${\varepsilon}-Fe_{2-3}(N,C)$.

• 한국수소및신에너지학회논문집
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• 제22권4호
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• pp.465-473
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• 2011

To find the optimum mixing ratio of WGS catalyst with $CO_2$ absorbent for SEWGS process, water gas shift reaction tests were carried out in a fluidized bed reactor using commercial WGS catalyst and sand (as a substitute for $CO_2$ absorbent). WGS catalyst content, gas velocity, and steam/CO ratio were considered as experimental variables. CO conversion increased as the catalyst content increased during water gas shift reaction. Variations of the CO conversion with the catalyst content were small at low gas velocity. However, those variations increased at higher gas velocity. Within experimental range of this study, the optimum operating condition(steam/CO ratio=3, gas velocity = 0.03 m/s, catalyst content=10 wt.%) to get high CO conversion and $CO_2$ capture efficiency was confirmed. Moreover, long time water gas shift reaction tests up to 20 hours were carried out for two cases (catalyst content = 10 and 20 wt.%) and we could conclude that the WGS reactivity at those conditions was maintained up to 20 hours.

• 한국식품영양과학회지
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• 제26권6호
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• pp.1021-1027
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• 1997

$CO_2$production in fermentation of dongchimi was measured and interrelated with changes in pH and titratable acidity. The effects of salt content and temperature on $CO_2$production rate were analysed. Fermentation of dongchimi showed drastic pH decrease in early stage and subsequent levelling off around 3.9, with linearly increased acidity up to 0.3~0.4% optimum quality. $CO_2$production of dongchimi could be analysed to consist of two consecutive stages of constant rate. The first stage $CO_2$production of higher rate moved to the second stage of lower rate when acidity rose beyond 0.3%. When compared to those of 1 and 2% salt content, dongchimi of 3% salt showed lower $CO_2$production rate in the 1st stage and slower acidity change through the whole fermentation period. However, it resulted in the product of highest $CO_2$accumulation at optimal ripeness because of consistent $CO_2$production of longer 1st stage period and relatively high $CO_2$production rate in 2nd stage. $CO_2$production depended on temperature less compared to acidity change(activation energy: 57.3 and 44.3kJ/mol for $CO_2$production of 1st and 2nd stages, respectively; 79.3kJ/mol for acidity change), which means higher ratio of $CO_2$production rate relative to acidity increase at lower temperature. Slower increase in acidity at low temperature also was shown to extend the period of 1st stage $CO_2$production. Therefore, low temperature fermentation was effective in producing the high $CO_2$content dongchimi at adequate acidity, which is desirable organoleptically.

• 아시안잔디학회지
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• 제18권2호
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• pp.97-104
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• 2004

Putting green의 높은 이산화탄소 함량은 많은 골프장 관리자들에게 있어서 green 관리시 항상 난제로 여겨져 왔다. 무기성 토양은 green 근권(根圈:토양 중에서 뿌리의 영향이 미치는 범위)에서 이용 가능한 자유산소를 제한하며 그로 인하여 뿌리발달을 방해하며 잔디성장을 위한 영양분이 용도를 제지시킨다. 이 실험은 현 운영되는 골프장 (South illinois, Carbondale, U,S,A) 에서 선택 되어진 아홉 개의 green 에서 근권의 $CO_2$ 함유량과 잔디품질 (Turf qualify Index) 사이의 관계성을 조사하기 위하여 실행되어졌다. 아홉개의 putting green에서 각 green 의 다섯 곳의 소구획을 무작위로 선택하여 1998년 8월 부터 1999년 8월 까지 일곱번의 반복으로 잔디품질, $CO_2$ 함유량, 수분함량과 수분 침투율 (Infiltration rate) 을 측정하였다. $CO_2$ 함유량은 이른 봄 보다 늦은 여름에 높았으며 $CO_2$ 함유량이 높아짐에 따라 잔디품질은 급격히 낮아졌다. 수분함량이 많을수록 $CO_2$ 함유량이 높았으며 반대로 수분 침투율은 낮아짐을 보였다. 높은 수분 침투율은 $CO_2$ 함유량을 감소시켰다. 결론적으로 알맞은 토양의 물리적 조건(수분 함량과 침투율)이 $CO_2$ 함유량과 잔디성장에 있어서 매우 중요한 역할을 함을 알 수 있다. 잔디품질의 향상을 위해 putting green root zone의 알맞은 배수와 함께 근권의 공기 조건이 매우 중요함이 이 실험을 통해 조사되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.419-422
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• 2001

The electrical properties of Pr$_{6}$O$_{11}$-based ZnO varistors composed of ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-Dy$_2$O$_3$- based ceramics were investigated with CoO content in the range of 0.5~5.0 mol%. As CoO content is increased, the average grain size and the density were increased in the range of 9.86~27.22 $\mu$m and in the range of 5.25-5.55 g/cm$^3$, respectively. The varistor voltage was decreased in the range of 235.32~86.01 V/mm due to the increase of average grain size with CoO content. The varistors doped with CoO in the rage of 1.0~2.0 mol% exhibited a high nonlinearity, in which is above 55 in the nonlinear exponent and below 1.5 $\mu$A in the leakage current. Increasing CoO content further greatly decreased the nonlinearity.ity.ity.

• 한국표면공학회지
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• 제36권3호
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• pp.256-262
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• 2003

The current efficiency and the composition of Zn-Cr and Zn-Cr-X (X : Co, Mn) alloy electrodeposits were investigated by using chloride bath with EDTA auditive and flow cell plating system. The current efficiency of Zn-Cr alloy decreased with increasing current density, while it increased with the content of Co and Mn of the Zn-Cr-X alloy bath in high current density region. The Cr content in Zn-Cr alloy increased from 1.4-2.7 to $28wt\%$ with increasing current density and the phase structure of the alloys changed from $\eta-Zn$ through $\eta-Zn+\gamma'-ZnCr\;to\;\gamma'-ZnCr$ with Increasing Cr content of the alloys. The Co content in Zn-Cr-Co alloys increased with Co content of the bath, while Cr content of the alloy increased or decreased in low current density region $(10-75A/dm^2)$ or high current density region $(75-100A/dm^2)$, respectively. $\gamma-ZnCo$ phase was formed in the Zn-Cr-Co alloy with above $9.0wt\%$ Co. The content of Mn and Cr in Zn-Cr-Mn alloys increased or decreased with the increase of current density in high current density region, respectively while Cr content of the alloy decreased noticeably with the increase of Mn content in the bath. Two phases of $\delta_1-ZnMn$ and $\gamma'-ZnCr$ were formed in the Zn-Cr-Mn alloy with above $8.6wt\%$ Mn.

• 원예과학기술지
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• 제35권3호
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• pp.300-313
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• 2017

'Unicon' cherry tomato (Solanum lycopersicum) is one of the most highly perishable horticultural crops due to its high water content and respiration rate. This study was carried out to assess the effect of continuous application of $CO_2$ (control [air], 3%, and 5%) on the quality and shelf life of cherry tomato fruits stored at $10^{\circ}C$ and $85{\pm}5%$ relative humidity (RH) at two maturity stages (pink and red). Continuous application of $CO_2$ did not affect the soluble solids content (SSC) or titratable acidity (TA) of the fruit at either maturity stage during storage. However, there was a significant difference among treatments in terms of flesh firmness, cell wall thickness, pectin content, vitamin C content, skin color, lycopene content, weight loss, ethylene production rate, respiration rate, and acetaldehyde and ethanol production. Fruits treated with 5% $CO_2$ maintained their high quality with regards to vitamin C, skin color ($a^*$), lycopene content, weight loss, physiological parameters (ethylene production rate, respiration rate, and volatile compounds), flesh firmness, cell wall thickness, and pectin content at both maturity stages compared with 3% $CO_2$ treatment and the control. Continuous application of $CO_2$ (5%) reduced the ethylene production rate and the production of volatile compounds during storage. Therefore, cherry tomato 'Unicon' fruit can be stored for two weeks without losing fruit quality at both maturity stages under continuous application of 5% $CO_2$ as a postharvest treatment.

• Journal of Ecology and Environment
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• 제42권1호
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• pp.1-11
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• 2018

Background: In the study, the effects of elevated $CO_2$ and temperature on the nitrogen content, carbon content, and C:N ratio of seven rare and endangered species (Quercus gilva, Hibiscus hambo, Paliurus ramosissimus, Cicuta virosa, Bupleurum latissimum, Viola raddeana, and Iris dichotoma) were examined under control (ambient $CO_2$ + ambient temperature) and treatment (elevated $CO_2$ + elevated temperature) for 3 years (May 2008 and June 2011). Results: Elevated $CO_2$ concentration and temperature result in a decline in leaf nitrogen content for three woody species in May 2009 and June 2011, while four herb species showed different responses to each other. The nitrogen content of B. latissimum and I. dichotoma decreased under treatment in either 2009 and 2011. The leaf nitrogen content of C. virosa and V. raddeana was not significantly affected by elevated $CO_2$ and temperature in 2009, but that of C. virosa increased and that V. raddeana decreased under the treatment in 2011. In 2009, it was found that there was no difference in carbon content in the leaves of the six species except for that of P. ramosissimus. On the other hand, while there was no difference in carbon content in the leaves of Q. gilva in the control and treatment in 2011, carbon content in the leaves of the remaining six species increased due to the rise of $CO_2$ concentration and temperature. The C:N ratio in the leaf of C. virosa grown in the treatment was lower in both 2009 and 2011 than that in the control. The C:N ratio in the leaf of V. raddeana decreased by 16.4% from the previous year, but increased by 28.9% in 2011. For the other five species, C:N ratios increased both in 2009 and 2011. In 2009 and 2011, chlorophyll contents in the leaves of Q. gilva and H. hamabo were higher in the treatment than those in the control. In the case of P. ramosissimus, the ratio was higher in the treatment than that in the control in 2009, but in 2011, the result was the opposite. Among four herb species, the chlorophyll contents in the leaves of C. virosa, V. raddeana, and I. dichotoma did not show any difference between gradients in 2009, but decreased due to the rise of $CO_2$ concentration and temperature in 2011. Leaf nitrogen and carbon contents, C:N ratio, and chlorophyll contents in the leaves of seven rare and endangered species of plant were found to be influenced by the rise and duration of $CO_2$ concentration and temperature, species, and interaction among those factors. Conclusions: The findings above seem to show that long-term rise of $CO_2$ concentration, and temperature causes changes in physiological responses of rare and endangered species of plant and the responses may be species-specific. In particular, woody species seem to be more sensitive to the rise of $CO_2$ concentration and temperature than herb species.

• 한국세라믹학회지
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• 제40권2호
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• pp.191-197
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• 2003

지구온난화의 주요원인인 $CO_2$의 분해를 위해 다양한 조성의 Sr 페라이트를 이용하여 $CO_2$분해능을 비교하였다. Sr 페라이트를 80$0^{\circ}C$까지 환원시킨 결과, Sr 페라이트 내 Sr 함량이 감소할수록 높은 온도에서 환원반응이 시작되었지만, 온도가 증가함에 따라 그 환원반응성은 높아졌다. 환원된 Sr 페라이트를 이용한 $CO_2$분해 반응에서는 Sr:Fe 조성비에 따라CO나 C의 생성량이 달라졌다. 이 반응에서 Sr 페라이트 내 Sr의 비율이 감소할수록 CO의 생성량은 증가하였으며, Sr의 비율이 증가할수록 페라이트 표면에 많은 양의 C가 흡착되었다. 따라서, $CO_2$분해 반응에 Sr 페라이트를 적용할 경우, 사용 조건에 따라 Sr:Fe의 조성비를 제어할 필요가 있다.