• 대한건축학회논문집:구조계
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• 제36권5호
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• pp.187-194
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• 2020

This study presents the energy-saving sequential control algorithm to handle indoor CO₂ and PM2.5 for the improvement of the air quality of school classrooms. To solve indoor air quality (IAQ) problems, air cleaning and ventilation systems are mainly used for school classrooms. Although air cleaning is able to collect PM2.5, it is difficult to remove harmful gas substances. The ventilation system is suitable to tackle CO and CO₂, the volume ventilation, however, is relatively small. In this paper, to remove CO₂ and PM2.5, the pollutant balance equation for improving indoor air quality is reviewed. The sequential control algorithm of the ventilation and air cleaning system with four levels of criteria is introduced for the effective removal of pollutants. The proposed sequential control algorithm confirms that indoor CO₂ and PM2.5 can be properly controlled below the standard value. In addition, the sequential operation of air cleaning and ventilation systems has shown significant improvement in IAQ compared to the independent ventilation system operation. Particularly, such systems are efficient when outdoor PM2.5 is high.

• Corrosion Science and Technology
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• 제4권6호
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• pp.236-241
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• 2005

Hydrogen induced cracking (HIC) is one of the hydrogen degradation phenomena of linepipe steels caused by $H_2S$ gas in the crude oil or natural gas. However, NACE TM0284-96 standard HIC test method is hard to satisfy the steel requirements for sour service application since it uses more severe environmental conditions than actual conditions. Therefore, in order to use steels effectively, it is required to evaluate HIC resistance of steels in the practical range of environmental severity. In this study, HIC resistance of two high strength low alloy (HSLA) steels being used as line pipe steels was evaluated in various test solutions with different $H_2S$ pressures and pH values. The results showed that the key parameter affecting crack area ratio (CAR) is $H_2S$ partial pressure of test solution when the pH value of test solution is not over 4. Hydrogen diffusivity was not a constant value, but it was rather affected by the hydrogen ion concentration (pH value) in the solution.

• KEPCO Journal on Electric Power and Energy
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• 제4권1호
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• pp.33-38
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• 2018

This study applied upgrades to the processes of a 10 MW wet amine $CO_2$ capture pilot plant and conducted performance evaluation. The 10 MW $CO_2$ Capture Pilot Plant is a facility that applies 1/50 of the combustion flue gas produced from a 500 MW coal-fired power plant, and is capable of capturing up to 200 tons of $CO_2$. This study aimed to quantitatively measure efficiency improvements of post-combustion $CO_2$ capture facilities resulting from process upgrades to propose reliable data for the first time in Korea. The key components of the process upgrades involve absorber intercooling, lean/rich amine exchanger efficiency improvements, reboiler steam TVR (Thermal Vapor Recompression), and lean amine MVR (Mechanical Vapor Recompression). The components were sequentially applied to test the energy reduction effect of each component. In addition, the performance evaluation was conducted with the absorber $CO_2$ removal efficiency maintained at the performance evaluation standard value proposed by the IEA-GHG ($CO_2$ removal rate: 90%). The absorbent used in the study was the highly efficient KoSol-5 that was developed by KEPCO (Korea Electric Power Corporation). From the performance evaluation results, it was found that the steam consumption (regeneration energy) for the regeneration of the absorbent decreased by $0.38GJ/tonCO_2$ after applying the process upgrades: from $2.93GJ/ton\;CO_2$ to $2.55GJ/tonCO_2$. This study confirmed the excellent performance of the post-combustion wet $CO_2$ capture process developed by KEPCO Research Institute (KEPRI) within KEPCO, and the process upgrades validated in this study are expected to substantially reduce $CO_2$ capture costs when applied in demonstration $CO_2$ capture plants.

• 한국가스학회지
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• 제25권6호
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• pp.66-73
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• 2021

본 연구에서 인증을 위한 표준가스 종류의 변화가 대형 천연가스 엔진에 미치는 영향을 살펴보기 위해 전부하 시험과 WHTC 모드 시험 조건에서 엔진 성능 및 배기 특성을 비교하고 그 결과를 분석하였다. 실험에 사용된 연료는 표준 가스 두 종류(G_r, G₂₃)와 시중에 유통되고 있는 천연가스, 총 3종류를 적용하였다. 연료 조성이 다른 3가지 천연가스의 실험결과 엔진 성능 특성은 질소 함유율이 높은 G₂₃ 연료에 대해서 토크, 연료소모율, 열효율 결과가 모두 다른 연료에 비해 악화되는 결과를 보였다. 또한 인증시험모드인 WHTC 모드에서 평가하였을 때, G₂₃ 연료를 적용한 경우 다른 두 연료에 비해 이산화탄소 및 일산화탄소 배출량은 감소하고 메탄, 질소산화물 및 입자상물질의 개수 배출량은 증가하여 질소산화물의 경우 EURO VI 규제치를 만족할 수 없었다.

• 한국기후변화학회지
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• 제5권4호
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• pp.339-348
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• 2014

Agro-ecosystem plays an important role in the mitigation of atmospheric $CO_2$ concentration through photosynthesis and soil carbon fixation. The perennial crops have capacity of carbon accumulation because they have lived for years in the same position. Carbon dioxide fixation occurs in the fruit orchard by photosynthesis and soil carbon sequestration. The objectives of this review are to introduce the fruit orchard as a carbon dioxide sink and to summarize the methods that measure $CO_2$ flux in the orchard. There are three difference methods (chamber, biomass, and eddy covariance method) to measure $CO_2$ exchanges on sites. However, there is no standard method suitable for fruit cultivation condition in Korea. Thus the standard method have to be developed in order to exactly estimate the carbon accumulation. In foreign studies, the carbon assessments were conducted in apple, peach, olive, grape orchard and so on. On the other hand the estimation of $CO_2$ exchange was carried out for apple and mandarine orchard in Korea. According to these results, fruit orchard is a $CO_2$ sink even though amount of carbon accumulation is smaller than the forest. To introduce certainly fruit orchard as greenhouse gas sink, long-term monitoring and further study have to be conducted under each planting condition.

• 한국입자에어로졸학회지
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• 제9권2호
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• pp.79-87
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• 2013

In this study, the characteristics of turbulent flow and collection efficiency for an one-stage electrostatic precipitator(ESP) with slit type collecting electrode for urban railway underground tunnels were obtained using computational fluid dynamics(CFD) commercial code FLUENT 6.3 and lab-scale experiments. The electrostatic precipitator was operated under high gas velocity(3~12m/s). Five different designs of collecting electrode, flat plate-type and a slit-type of 3mm, 5mm, 7mm and 10mm slit width and four various gas velocity(3, 6, 9, and 12m/s) were used and applied. A standard k-${\varepsilon}$ model in CFD commercial code FLUENT 6.3 was used for flow simulation. The flow simulation results showed that the turbulent intensity of flat plate-type was higher than slit-type under all gas velocity conditions and also the turbulent intensity of flat plate-type was increased continuously, but in case of slit-type was maintained at constant range. And, the turbulent intensity was decreased according to increasing of slit width. The experimental results showed that the collection efficiency of slit-type was higher than flat plate-type under all gas velocity conditions. And, over 6m/s gas velocity condition, the collection efficiency of 5mm and 7mm was highest, when compared to 3mm and 10mm.

• 한국분무공학회지
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• 제20권3호
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• pp.149-155
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• 2015

With increasing of GDP, the registration number of passenger cars has exceeded 20 million last year in Korea. Especially, the registration number of the diesel engine vehicles has been increasing. However, the WHO(World Health Organization) IARC (International Agency for Research on Cancer) has reported that diesel engine exhaust gas is an one of HAPs, which has carcinogenic for human, and they have designated it to Group 1. To solve this problem, exhaust gas from diesel engines has to be controlled. Thus, it has been controlling by European regulatory standard in Korea. On the other hand, in order to meet the enhanced emission regulations, all manufacturing company applied $NO_x$ control device to vehicles such as EGR (Exhaust Gas Recirculation), SCR (Selective Catalytic Reduction) and so on. However, these devices (EGR, SCR) were operated by difference reaction mechanism respectively, and the composition of exhaust gas would be differenced from that of them. In this study, it was conducted to evaluate variety characteristics on changing of exhaust gas composition by each $NO_x$ control device, and the heavy duty diesel trucks were chosen as experimental vehicles. From the result, it revealed that vehicles (with EGR) were discharged higher THC as 52.5% than that of others (with SCR). However, it did not followed that trend, in the case of CO; it was discharged as 57.2% lower than that of others (with SCR). In the future, these data would be used to apply to efficient $NO_x$ control device for meeting to EURO 6.

• 한국농공학회논문집
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• 제56권6호
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• pp.55-62
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• 2014

Torrefaction is considered as a promising pre-treatment for thermochemical utilization of biomass. Torrefaction temperature and time are the critical operation parameters. In this study, investigated were the effects of reaction temperature and time on product composition of torrefaction. scanning electron microscope (SEM) images and thermo gravimetric analyzer (TGA) results were also compared for the effects of the operating parameters. SEM images showed that the pores were observed at the temperature of $250^{\circ}C$ for 30 minutes. Rapid decreases in weight were observed the temperature between 200 and$400^{\circ}C$. Higher heating value of the torrefied biomass was over 5,000 kcal/kg at the temperature of $250^{\circ}C$ for 45 minutes. Energy density, which is defined as the ratio of the energy yield over the mass yield was 1.36 at the temperature of $250^{\circ}C$ for 45 minutes. The energy density was higher up to 1.6 at the temperature of $280^{\circ}C$, which indicates greater loss in mass. The major components of the gas produced in the torrefaction were $CO_2$ and CO, with traces of methane. The total amount of gas was 31.54 l/kg and the calorific value of the gas was $1,164.4Kcal/Nm^3$ at the temperature of $250^{\circ}C$ for 30 minute reaction time. Based on the results of this study, the temperature of effective torrefaction is about $250^{\circ}C$ for 30 to 45 minutes of reaction time. Considering the heating value, it is desirable to utilize the gas for efficient process of torrefaction.

• 한국화재소방학회논문지
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• 제23권5호
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• pp.117-124
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• 2009

본 연구의 목적은 실내 유해가스의 제거효율 향상을 위하여 기계 환기시스템의 환기성능을 분석하는 것이다. 환기성능은 ASTM E741-83 기준에 의거하여 체강법을 사용하여 평가하였다. 추적가스($CO_2$) 기법을 사용하여 환기율과 급기/배기구 위치에 따른 환기성능이 평가되었다. 결과적으로 $CO_2$ 농도는 환기율 증가에 따라 지수적으로 감소하며 환기농도가 증가함을 파악하였다. 2종 환기방식 시스템의 환기성능이 1종 환기방식 또는 3종 환기방식 보다 더 우수하였다. 환경공조챔버에서 자연감쇠의 경우와 비교하여 급기량 570Lpm에서 1시간 후에 재실자가 없는 경우의 환기성능은 55%까지 증가하였고 1인 재실자가 있는 경우의 환기성능은 25%까지 증가하였다. 사무실에서 급기량 570Lpm인 경우 환기성능은 자연감쇠와 비교하여 15% 이상 크게 나타났다.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2003년도 추계학술대회 논문집
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• pp.362-363
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• 2003

지구 온난화가 심화되면서 국제적으로 기후변화 협약에서는 한층 강제력 있는 온실기체의 감축목표를 권고하고 있다. 지난 1998년에 교토 기후협약에 가입한 우리나라도 실질적인 감축목표를 결정해야 하고 능동적으로 대처해야 하는바, 이를 소홀히 한다면 무역뿐만 아니라 산업활동에도 차질이 빚어질 것이다. 이를 위해 가장 기본적인 자료라 할 수 있는 온실기체($CO_2$, CH$_4$, $N_2$O, CFCs, PFCs)의 지속적이고도 체계적인 관측과 세계적으로 인정받을 수 있는 정확한 측정값의 제시가 필수적이다. (중략)