• Transactions of the Korean hydrogen and new energy society
• /
• v.24 no.4
• /
• pp.334-339
• /
• 2013

In this study, as a candidate of the carbon dioxide ($CO_2$) absorbents, the mixture solution of polyethylene glycol dimethyl ether (PEGDME) and tetrahydrofuran (THF) were investigated. $CO_2$ absorption rate was measured by using high pressure $CO_2$ screening equipment in the range of 1 - 10wt% THF. Absorption capacity of the mixture solution was also estimated. Based on the results, we found that mixture solution containing THF had higher absorption rate and $CO_2$ loading capacity compared to PEGDME at $25^{\circ}C$.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2011.04a
• /
• pp.436-440
• /
• 2011

본 연구는 산불발생에 따른 온실가스 배출량 추정을 위한 기초 data 제공에 주안점을 두고 산림연료를 대상으로 연소실험을 수행하였다. 연료의 대상은 참나무(굴참, 떡갈, 신갈, 갈참, 졸참, 상수리)를 대상으로 부위별(생엽, 가지, 수피) 채취하여 사용하였으며, 콘칼로리미터를 이용하여 $CO_2$ 배출량을 분석하였다. 중량 50g의 연료 기준에 대한 $CO_2$ 배출량은 생엽 42.38~95.41g, 가지 82.92~113.10g, 수피 72.64~100.70g 정도 범위에서 $CO_2$를 배출하는 것으로 나타났다. 부위별 평균배출량을 살펴보면, 생엽 72.10g, 가지 101.88, 수피 86.46g 정도의 값을 보여 가지부위가 가장 많은 $CO_2$를 배출하는 것을 알 수 있었으며, 또한, $CO_2$를 상대적으로 많이 배출한 수종으로는 상수리나무인 것으로 나타났다.

• Food Science and Biotechnology
• /
• v.15 no.1
• /
• pp.13-18
• /
• 2006

Mandarin juice was processed using a continuous high pressure $CO_2$ system. Response surface methodology was used to investigate the effects of the processing parameters such as temperature, pressure, residence time, and %(w/w) ratio of $CO_2$ to juice on total aerobic count (TAC), pectinesterase (PE) activity, cloud level, $^{\circ}Brix$, pH, and titratable acidity (TA) of the juices. Maximum log reduction (3.47) of TAC was observed at $35^{\circ}C$, 41.1 MPa, 9 min residence time, and 7% $CO_2$. PE was inactivated by 7-51%. The cloud was not only retained but was also enhanced by 38%. Lightness and yellowness increased, and redness decreased. The processing temperature and % $CO_2$/juice ratio significantly affected high pressure $CO_2$ processing of the juice in terms of pasteurization, PE inactivation, cloud increase, and color change. The $^{\circ}Brix$, pH, and TA before and after treatment remained unchanged.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.1652-1655
• /
• 2008

Indoor air quality (IAQ) of subway becomes a key issue as the IAQ guidelines for public transportation published. There are two major sources regarding IAQ of subway; One is the sources coming from outdoor air and the other is sources of inside. Particulate matters smaller than 10 micrometer (PM10) and carbon dioxide ($CO_2$) are recognized as the one of the most severe pollutants in Korea. The source of PM10 is mainly coming from outdoor air, however, the source of $CO_2$ is coming from passengers exhaust. According to the guidelines, the level of $CO_2$ should be lower than 2500ppm for normal operating time and lower than 3500ppm for rush hour. In order to satisfy these guidelines, the volume of mechanical ventilation should be increase which consumes extra energy for heating or cooling. Therefore, the optimum volume of mechanical ventilation should be calculated for energy saving. In this study, we measured the natural ventilation rate by door-opening which can reduce the load of mechanical ventilation. The $CO_2$ generator and sensors were used to measure the change of $CO_2$ by periodic door-opening of subway.

• Textile Coloration and Finishing
• /
• v.31 no.1
• /
• pp.14-24
• /
• 2019

In this study, dyeability of PET fabric was investigated depending on dyeing temperature, pressure, and leveling time using laboratory scale supercritical $CO_2(scCO_2)$ dyeing machine. Dyeing temperature, pressure, leveling time were varied from 100, 120, $130^{\circ}C$, 150, 200, 250bar, 40, 60, 80, 100min, respectively. It is proved that the higher temperature of $scCO_2$ dyeing process, the higher K/S value and the lower $L^*$ value, which in turn means the lower amount of dyeing molecules remained after process done. Compared 200bar with 250bar of dyeing pressure, $scCO_2$ dyeing fabrics under 250bar appeared to have a lower $L^*$ value, a higher K/S value than those from 200bar, meaning that dyeing color turns to darker with higher dyeing pressure. The experiments showed that the most ideal condition for $scCO_2$ dyeing process is $120^{\circ}C$, 250bar for 60 - 100min of leveling time.

• Journal of the Korean Applied Science and Technology
• /
• v.31 no.3
• /
• pp.394-401
• /
• 2014

In order to minimize a building energy consumption with ventilation, a development of smart ventilation system is very important. In this study, a dry adsorbent that is main element of smart ventilation system was developed for removing indoor $CO_2$, and evaluate the adsorption performance. Specific surface area, pore characteristic and crystal structure of the modified sorbent was measured to analyze physical properties. From this analysis, it was found that the developed absorbent has a low specific surface area, due to mesopores of substrate was filled with metal contained raw material. Additionally, through analysis of the adsorption properties, the developed adsorbent was shown a adsorption form of mesopore (type IV), which means adsorption amount was rapidly increased at the part of high-pressure. Order to applying for the field, chamber test was performed. Continuous column tests (2,500 ppm) and batch chamber tests ($4m^3$, 5,000 ppm) showed $CO_2$ removal efficiency of 95% and 88% within 1 hour, respectively.

• Clean Technology
• /
• v.9 no.4
• /
• pp.179-187
• /
• 2003

The technology of fluidized bed to use dry sorbent can be new technology that reduce the operating cost and make efficient operation. Therefore, this study investigated $CO_2$ control by dry sorbents with operating variables in a fluidized bed, compared with fixed bed for $CO_2$ adsorption capacity and pressure drop, and presented the $CO_2$ adsorption capacity of activated carbon, molecular sieve 5A, molecular sieve 13X, and activated alumina. As the results of this study, the basic data could be achieved for operation of fluidized bed process, and fluidized bed process presented relatively high $CO_2$ adsorption capacity and low pressure drop with the increase of gas velocity. In addition, molecular sieve 5A showed 1.1~3.0-fold later breakthrough point and 1.1~2.7-fold higher adsorption capacity than the other dry sorbents.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.1
• /
• pp.63-68
• /
• 2018

This paper presents an integrated photochemical reaction system (i.e., an artificial leaf) that uses earth-abundant catalysts for artificial photosynthesis with a carbon dioxide ($CO_2$) fixation process. The performance of the system was investigated in terms of the energy capture and conversion capabilities. A wireless configuration was achieved by directly doping cobalt oxide as an oxygen-evolving catalyst for water splitting reaction on the illuminated surface of photovoltaic (PV) cell, as well as molybdenum disulfide ($MoS_2$) as an efficient catalyst for $CO_2$ reduction on the back substrate surfaces of the PV cell. The system produces hydrogen and carbon monoxide (CO) as sustainable fuels (i.e., synthesis gas) at around 4.5% efficiency, which implies more than 75% catalytic efficiency at the cathode. The process of solar-driven $CO_2$ conversion and water-splitting reaction is contained in one system, which is one step closer to the successful realization of artificial photosynthesis.

• Journal of Korean Society of Environmental Engineers
• /
• v.37 no.11
• /
• pp.597-606
• /
• 2015

This work investigates the carbonation of KOH-dissolved methanol and ethanol solution systems carried out for $CO_2$ fixation. Potassium methyl carbonate (PMC) and potassium ethyl carbonate (PEC) were synthesized during the reaction in each solution as the solid powder, and they were characterized in detail. The amount of $CO_2$ chemically absorbed to produce the PMC and PEC precipitates were calculated to be 97.90% and 99.58% of their theoretical values, respectively. In addition, a substantial amount of $CO_2$ was physically absorbed in the solution during the carbonation. PMC precipitates were consisted of the pure PMC and $KHCO_3$ with the weight ratio of 5:5, respectively. PEC precipitates were also mixture of the pure PEC and $KHCO_3$ with the weight ratio of 8:2, respectively. When these two precipitates were dissolved in excess water, methanol and ethanol were regenerated remaining solid $KHCO_3$ in the solutions. Therefore, the process has the potential to be one of the efficient options of CCS and CCU technologies.

• Journal of Bio-Environment Control
• /
• v.26 no.2
• /
• pp.140-145
• /
• 2017

This study was conducted to find out the effects of $CO_2$ fertilization (1,000ppm) on the quality and storability of 'Maehyang' strawberry fruits. Qualities such as firmness, soluble solid, and acidity of strawberry fruits showed higher numbers in those treated with $CO_2$ fertilization compared to those after harvest. Strawberry fruits were stored at $8^{\circ}C$; MA condition using $20,000cc{\cdot}m^{-2}{\cdot}day^{-1}{\cdot}atm^{-1}$ OTR (oxygen transmission rate) films and conventional condition using unsealed PE box stored for 20 and 10 days, respectively. Fresh weight loss rate was less than 1.0% in MA storage regardless of $CO_2$ fertilization treatment. Concentrations of oxygen, carbon dioxide, and ethylene in OTR films did not show any significant difference between $CO_2$ fertilization treatment and control (nontreatment) during storage. $CO_2$ fertilization treatments maintained higher firmness after storage regardless of storage methods, but soluble solid, acidity, and surface color did not differ among the treatments. Visual quality and off-flavor based on sensory evaluation was the highest in $CO_2$ fertilization treated strawberry and stored at a MA condition, and was the lowest in $CO_2$ fertilization treated strawberry and those stored in a conventional condition, respectively. The fungal incidence rate of strawberry fruits showed less in $CO_2$ fertilization treatment than control during both MA and conventional storage. These results suggest that $CO_2$ fertilization can improve firmness, increase visual quality after harvest and storage at $8^{\circ}C$, and the MA storage method enhances the shelf-life of 'Maehyang' strawberry fruits.