This study was aimed to determine the changes in CO2 concentration according to the temperatures of daytime and nighttime in the CO2 supplemental greenhouse, and to compare calculated supplementary CO2 concentration during winter and spring cultivation seasons. CO2 concentrations in experimental greenhouses were analyzed by selecting representative days with different average temperatures due to differences in integrated solar radiation at the growth stage of leaf area index (LAI) 2.0 during the winter season of 2022 and 2023 years. The CO2 concentration was 459, 299, 275, and 239 μmol·mol-1, respectively at 1, 2, 3, and 4 p.m. after the CO2 supplementary time (10:00-13:00) under the higher temperature (HT, > 18°C daytime temp. avg. 31.7, 26.8, 23.8, and 22.4°C, respectively), while it was 500, 368, 366, 364 μmol·mol-1, respectively under the lower temperature (LT, < 18°C daytime temp. avg. 22.0, 18.9, 15.0, and 13.7°C, respectively), indicating the CO2 reduction was significantly higher in the HT than that of LT. During the nighttime, the concentration of CO2 gradually increased from 6 p.m. (346 μmol·mol-1) to 3 a.m. (454 μmol·mol-1) in the HT with a rate of 11 μmol·mol-1 per hour (240 tomatoes, leaf area 330m2), while the increase was very lesser under the LT. During the spring season, the CO2 concentration measured just before the start of CO2 fertilization (7:30 a.m.) in the CO2 enrichment greenhouse was 3-4 times higher in the HT (>15°C nighttime temperature avg.) than that of LT (< 15°C nighttime temperature avg.), and the calculated amount of CO2 fertilization on the day was also lower in HT. All the integrated results indicate that CO2 concentrations during the nighttime varies depending on the temperature, and the increased CO2 is a major source of CO2 for photosynthesis after sunrise, and it is necessary to develop a model formula for CO2 supplement considering the nighttime CO2 concentration.

This study was carried out to investigate the effects of supercritical carbon dioxide (SC-CO2) extracts from sweet potatoes (SP) and watermelon (WM) on the oxidative stability of perilla seed oils (POs) over the existing ones. A comparison was done between the oxidative stability of perilla oil (PO) after the addition of 0.1% of SP, and WM extracts and PO without extract. The oxidative stability was measured based on the viscosity, acid value (AV), peroxide value (POV), antioxidant (DPPH) activity, p-anisidine value (p-AV), and fatty acid composition. The viscosities ranges were: PO without extract, from 53.99±0.99 to 74.38±1.61 cps, PO with SP extract, from 53.99±0.10 to 58.73±0.8 cps, and PO with WM extract, from 53.98±0.10 to 56.00±0.70 cps. While the PO containing the SC-CO2 extracts had significantly lower AV, POV, and p-AV, their antioxidant activity was approximately 10 times higher than that of the PO without extract. There were no significant differences in fatty acid composition between SC-CO2 extracts added groups and PO without extract (p<0.05). The findings of this study confirmed that the SC-CO2 extracts from sweet potatoes and watermelon enhanced the oxidative stability of perilla seed oils, and are potential natural antioxidants for use in the food industry.

전 세계 화석 연료 사용이 지속적으로 증가함에 따라 공기 중 이산화탄소(CO2) 농도가 수 세기에 걸쳐 증가하고 있다. 대기로의 CO2 배출을 줄이기 위한 방법으로, 주요 배출원인 발전소와 공장에 적용할 수 있는 이산화탄소 포집 및 저장 (carbon capture and sequestration, CCS) 기술이 개발되고 있다. 기후 변화 완화 정책에 따라 negative emission 기술로 언급 되는 공기 중 CO2 직접 포집 기술(direct air capture, DAC)은 CO2 농도가 0.04%로 매우 낮기 때문에 기존의 CCS 기술에 적 용된 기술과 달리 흡착제를 이용한 저농도 CO2 포집 연구에 집중되어 있다. DAC 분야는 주로 CO2의 흡착을 이용한 습식 흡 착제, 건식 흡착제, 아민 기능화된 소재, 이온교환 수지 등이 연구되었다. 흡착제 기반 기술은 흡착제 재생에 따른 고온 열처 리 공정이 필요하기 때문에 추가적인 에너지 소모가 없는 분리막 기반의 공기 중 CO2 포집 기술의 잠재력이 크다. 분리막은 특히 실내 공기 CO2 저감 환기 시스템 및 실내용 스마트팜(smart farm) 시스템의 연속적인 CO2 공급에 사용될 수 있을 것으 로 기대된다. CO2 처리 기술은 기후 변화를 완화하기 위한 수단으로 개발이 지속되어야 하며 효율적인 공정 설계와 소재 성 능 향상을 통해 공기 중 CO2 포집의 효율을 높일 수 있을 것이다.

본 연구에서는 이산화탄소 포집 및 물 재이용을 위한 통합 시스템으로서 정삼투 공정의 적용 가능성에 대한 평가를 수행하였다. 해당 통합 공정은 이산화탄소 배출 저감을 위해 화력발전소에 적용되고 있는 습식 이산화탄소 포집설비에 정삼투 기반 공정을 추가함으로써 이산화탄소 포집뿐만 아니라 물 재이용 및 냉각수 생산을 동시에 달성할 수 있다. CO2를 흡수한 5M의 모노에탄올아민(습식용매)을 유도용액으로 적용한 결과 40 LMH (FO mode) 및 85 LMH (PRO mode)라는 매우 높은 수투과도를 얻을 수 있었다.

The South Korean Ministry of the Environment has revised the laws relating to the management of interior air quality for multiple use facilities, and recommends maintaining carbon dioxide (CO2) concentration in passenger vehicles below 1000 ppm during operation in urban areas of large cities. However, the interior CO2 concentration of passenger vehicles can rapidly increase and exceed 5000 ppm within 30 min, as observed when two passengers are traveling in urban areas of the South Korean city of Jeonju with the air conditioner blower turned off and the actuator mode set to internal circulation mode. With four passengers, CO2 concentration can reach up to 6000 ppm within 10 min. To counter this, when the actuator is set to external mode, CO2 concentration can be maintained below 1000 ppm, even after a long period of running time. As part of the air conditioning system, alkali-treated activated carbon fiber filters are considered to be far superior to the commercial non-woven filters or combination filters currently commonly in use.

Insecticidal effect of carbon dioxide(CO2) was carried out for the environment-friendly control of insect in vegetable plug seedling greenhouse. Korean melon, pepper, tomato and strawberry were tested. Insects were performed on Myzus persicae, Tetranychus urticae, Bemisia tabaci. Plants and insect were placed in closed container and the 4 concentration(0%, 25%, 50%, 100%) injected into container and investigated plant damage and the insecticidal effect over time. Damage of korean melon was appeared in the all concentration. Pepper was not injured until the 3 hours at 50% concentration and tomato also was not injured until the 6 hours at all concentration. Strawberry was not injured all concentration. The 100% mortality of Myzus persicae was appeared over 3 hours-100%, 12 hours-50% and 24 hours-25%, Tetranychus urticae was appeared over 3 hour-100%, 12 hours-50% and 24 hours-25% and Bemisia tabaci was appeared over 6 hours-100% and 12 hour-50%.

The objective of this study was to evaluate size-different chitosan nanoparticles as a CO2 indicator. CO2 gas is dissolved to form H2CO3 which makes the solution acidic. Chitosan is acid soluble and its appearance (turbidity) changes depending on pH in aqueous solution. Two size-different chitosan nanoparticles were fabricated by ionic gelation between chitosan (0.30 and 0.50%, w/v) and 0.07% sodium tripolyphosphate (TPP) solution. The sizes of chitosan nanoparticles were 630.77 and 1194.87 nm, respectively. To investigate the effect of chitosan nanoparticles as CO2 indicator, the initial pH of chitosan nanoparticle suspension was adjusted to 8.0. Thereafter, 100% CO2 gas was injected into the chitosan nanoparticle suspension, and the changes of pH and absorbance (600 nm of absorption wavelength) of the suspension over time were measured for 28 min. Absorbance at the appearance transition and its corresponding time was calculated using logistic function (R2> 0.99).As a result, pH of chitosan nanoparticle suspension decreased rapidly under CO2 gas injection for 10 min and finally reached around 6.0. In addition, there was significant difference in appearance transition time which was6.62 and 12.45 min for small- and large-sized chitosan nanoparticle suspensions, respectively. This study suggests that chitosan nanoparticle suspension might be useful as a food quality indicator for CO2 emitting foods such as fermented foods.