• Journal of Forest and Environmental Science
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• v.34 no.2
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• pp.153-161
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• 2018

Ozone absorbs ultraviolet light which is harmful to life. However, the recent increase of ambient ozone level due to climate change is becoming the cause of stimulating human eyes, affecting respiratory system, and damaging crops. In this paper, a study was conducted at the Taehwa Research Forest (TRF) of Seoul National University with the purpose of analyzing the characteristics of forest air chemistry based on the measurement of BVOCs emitted from forests and investigating the correlation of BVOCs with ozone generation. The results showed that levels of isoprene and MVK (Methyl Vinyl Keton)+MACR (Methacrolein) were high in summer, but level of monoterpene was high in spring. Ozone level was high from the middle of May to the middle of June, which was before the rainy season. Comparison of the correlation between ozone and isoprene during the measurement period at the TRF showing limited NOx showed that the $R^2$ was correlated with a low value of about 0.4. However, when the isoprene was actively produced from 6:00 AM to 6:00 PM, correlation analysis showed that $R^2$ was about 0.9, while monoterpene started to increase in the afternoon, and decreased level of ozone at night. Correlation analysis showed negative correlation. Forests have two characteristics: not only the formation of ozone but also the decomposition of ozone.

• New & Renewable Energy
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• v.5 no.2
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• pp.15-24
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• 2009

As new small scale LFG (landfill gas) energy project model which can improve economic feasibility limited due to the economy of scale, LFG-Microturbine combined heat and power system with $CO_2$ fertilization into greenhouses was proposed and investigated including basic design process prior to the system installation at Gwang-ju metro sanitary landfill. The system features $CH_4$ enrichment for stable microturbine operation, reduction of compressor power consumption and low CO emission, and $CO_2$ supplement into greenhouse for enhancement plant growth. From many other researches, high $CO_2$ concentration was found to enhance $CO_2$ assimilation (also known as photosynthesis reaction) which converts $CO_2$ and $H_2O$ to sugar using light energy. For small scale landfills which produce LFG under $3\;m^3$/min, among currently available prime movers, microturbine is the most suitable power generation system and its low electric efficiency can be improved with heat recovery. Besides, since its exhaust gas contains very low level of harmful contaminants to plant growth such as NOx, CO and SOx, microturbine exhaust gas is a suitable and economically advantageous $CO_2$ source for $CO_2$ fertilization in greenhouse. The LFG-Microturbine combined heat and power generation system with $CO_2$ fertilization into greenhouse gas to enhance plant growth is technologically and economically feasible and improves economical feasibility compared to other small scale LFG energy project model.

• Journal of Power System Engineering
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• v.19 no.3
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• pp.16-21
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• 2015

Nitrous oxide($N_2O$) concentration in the atmosphere has been constantly increased by the human activities with industrial growth after the industrial revolution. One of factors to increase $N_2O$ concentration in the atmosphere is the $N_2O$ emission caused by the combustion of marine fuel. Especially, a sulfur component included in marine fuel oils is known as increasing the $N_2O$ formation in diesel combustion. Form this point of view, $N_2O$ emission from a ship is not negligible. On the other hand, Exhaust gas recirculation(EGR) that have thermal, chemical and dilution effect is effective method for reducing the NOx emission. In this study, an author investigated $N_2O$ reduction by using EGR on a direct injection diesel engine. The test engine was a 4-stroke diesel engine with maximum output of 12 kW at 2600rpm, and operating condition of the engine was a fixed load of 75%. The experimental oil was a blend-fuel that were adjusted with sulfur ratio of 3.5%, and EGR ratio of 0%, 10%, 20% and 30%. In conclusion, diesel fuel that contained 3.5% sulfur component increased $SO_2$ emission in exhaust gas, and increment of EGR ratio reduced NO emission. Moreover, $N_2O$ emission was decreased as over 50% at EGR ratio of 10% and reduced 100% at EGR ratio of 30% compared with $N_2O$ emission of 0% EGR ratio.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.34-39
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• 2006

1. 철도, 도로, 항공, 해운 등 교통수단별 현황을 조사한 결과, 현재까지의 교통정책이 도로교통 우선 위주였기 때문에 철도는 뛰어난 환경성 및 경제성을 가지고 있음에도 불구하고 수송분담율이 비교적 저조한 편이었다. 그러나, 향후 정부의 사회기반시설 구축에 있어서 국가 기간 철도망 확대와 대도시 지하철 및 경량전철 건설을 통한 도심철도망과 간선철도망의 연결 등을 통하여 철도의 이용이 훨씬 용이해질 것으로 보이며 이에 따라 철도의 이용률도 크게 상승할 것으로 예상된다. 2. 교통수단별 일반현황은 다음과 같다. 1) 철도교통은 여객수송량이 다소 증가하고 있는 추세였는데, 2004년 KTX의 개통으로 인하여 여객수송량이 급증하였으나, 화물수송은 약간 감소하는 추세이다. 2) 도로교통은 공로의 경우 이용량이 크게 감소하고 있으나, 자가용의 경우에는 승용차의 급증에 의하여 도로의 분담률이 증가하고 있다. 그러나, 도로망의 확충이 자동차의 증가량을 따르지 못하는 것과 자동차가 도시에 밀집됨에 따른 교통체증에 따라 자가용 차량의 1일 평균 주행거리가 짧아지는 등 수송량이 크게 증가하지는 않고 있다. 3. 각 교통수단별 환경경제성을 조사한 결과는 다음과 같았다. 1) 단위수송량당 에너지 소비율은 여객의 경우 철도가 75.97kcal/인 km에 불과한 반면에 버스는 415.43, 택시는 1,192.24kcal/인 km에 달하여 각각 철도의 5.5배 및 15.7배나 많은 에너지를 소비하는 것으로 나타났다. 화물의 경우에도 철도는 105.98kcal/톤 km에 불과한 반면에 도로는 1,674.21kcal/톤 km에 달하여 철도의 무려 15.8배의 에너지를 사용하는 것으로 나타나, 철도가 에너지 효율성 면에서 도로 교통수단보다 월등히 앞서는 친환경적이면서 경제적인 교통수단임을 알 수 있다. 2) 도로와 철도의 단위수송량 당 CO의 배출량은 도로가 1,531.2kg/백만인 km로 철도의 167.4kg/백만인 km에 비하여 9배나 되었다. 그러나, 탄화수소의 경우는 도로가 216.5kg/백만인 km으로 철도의 68.0kg/백만인 km의 3배를 넘는다. 미세먼지의 경우는 도로가 철도보다 약간 더 많은 수준이었으나, NOx와 $SO_2$는 오히려 철도가 오히려 약간 더 높게 나타났다.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.156-165
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• 2014

This paper is the first investigation on the effect of flow control methods on the part load performance in a spark ignition engine. For comparison of the methods, two control devices, port throttling and masking, were applied to a conventional engine without any design change of the intake port. Steady flow evaluation shows that steady flow rates per unit opening area and swirl ratio are very low compared with the port throttling and saturated from mid-stage valve lift, however, swirl increases slightly as the lift is higher in case of 1/4 masking control. In the part load performance, the effect of simple port throttling on lean misfire limit expansion is limited and insufficient; on the other hand a masking improves the limit considerably without any port modification for increasing swirl. Also the results show that the intake flow control improves the combustion with following two mechanisms: stratification induced by the combination of the flow pattern and the fuel injection timing attribute to ignition ability and the intensified flow ensure fast burn. In addition fuel consumption reduces under the flow controls and the reduction rate is different according to the operation conditions and control methods. At the Stoichiometric and/or low speed and low load the throttling method is more advantageous; however vice versa at lean and high load condition. Finally, the throttling is more efficient for HC reduction than masking, on the other side the NOx emissions increase under the masking and decrease under the port throttling compared with conventional port scheme.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.81-89
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• 2014

This study researched on the effect of HP/LP-EGR system to improve fuel consumption of Low Temperature Combustion Engine. Firstly, low temperature combustion engine with HP/LP-EGR system was established using 6.0L wastegate turbocharger HDDI engine. And suppliable EGR rate of the engine was proven to be enough to realize stable low temperature combustion. Then, optimum operating strategy was founded to develop fuel consumption of the engine. Control parameters were HP/LP-EGR valve and IPCV(Intake Pressure Control Valve) duty. Experiments method was that characteristics of the engine were measured and analyzed according to HP/LP-EGR strategies while EGR rate was fixed. Operating range for the strategy were divided into three parts, low load for low temperature combustion, high load for conventional diesel combustion, and transient condition. Finally, with the above strategy of this study, BSFC of the engine was improved about 2% compared to the base engine, and emission level, NOx and PM, met Tier4Final emission regulation.

• Journal of Power System Engineering
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• v.20 no.2
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• pp.51-57
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• 2016

Non-esterified biodiesel fuel is cheaper than esterified that because of a simple manufacturing process that only consists of filtering. Applicability of this on diesel engine with electronic control system was accomplished, then optimization adopting a fractional factorial design and response surface methodology was carried out at 25% and 50% of engine load in this study. Pressure of common rail and injection timing mainly effected on responses as specific fuel oil consumption and nitrogen oxides regardless of engine load. Estimations were 310.3 g/kWh of specific fuel oil consumption and 237 ppm of nitrogen oxides at 25% load, and 233.2 g/kWh of specific fuel oil consumption and 730 ppm of nitrogen oxides at 50% load. Tests to verify these estimations were accomplished and as the results, specific fuel oil consumption was 300.4 g/kWh and NOx was 277 ppm at 25% load and 236.8 g/kWh and 573 ppm at 50% load.

• Journal of Korea Soil Environment Society
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• v.4 no.2
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• pp.185-192
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• 1999

To assess the soil quality of Chonan City, soil analyses were conducted according to the 14 different sampling sites. The soil pH of the agricultural area near the expressway was lower than that of the other farming area, which indicated that this acidification was probably attributed to the acid rain caused by the traffic exhaust gas such as SOx and NOx. Acidification was more severe in the dry farming area than in the rice paddy area. All concentration of 6 different heavy metals (As, Cu, Cd, $Cr^{6+}$, Hg, Pb) and organic contaminants (cyanide, organic-p, PCBs, phenols) were found to be lower than the standard of soil pollution. The concentration of BTEX also lower than the standard of soil pollution. An assessment using the SPI (Soil Pollution Index). which was developed to estimate an overall soil quality, was performed. Each SPC (Soil Pollution Score) were evaluated with the results of the data from this study. The soil quality of most area of Chonan City was determined to Class 1 , which indicated that the soil was healthy.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.116-116
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• 2011

바이오 가스 플랜트의 혐기소화 공정에서 발생하는 바이오 가스는 중 유해가스인 황하수소($H_2S$)는 부식성 가스로 수천 PPM농도를 함유하여, 발전기나 가스보일러로 이용하는 경우에는 $H_2S$를 제거하는 탈황공정이 반드시 필요하다. 탈황방식에는 산화철 탈황(건식 탈황)과 생물 탈황이 현재 많이 사용되고 있어나 산화철 탈황은 산화철 pellet이 유화철에 변화하면 탈황능력이 저하되어 pellet을 교환해야 하며 많은 비용이 발생한다. 생물 탈황 방식은 유황산화세균의 서식활동조건(온도, 반응시간, 산소량)확보가 반드시 필요하여 높은 운전기술을 필요로 한다. 본 연구에서는 바이오가스 전처리 기술 중 활성탄 또는 약액을 이용한 기존의 탈황정제방식보다 흡착성능이 뛰어난 이온교환섬유를 이용하여, 황화수소($H_2S$)를 95% 이상 제거할 수 있는 고효율 섬유상 이온촉매 악취제거 시스템 개발을 수행하였다. 이온교환섬유는 방사선 조사를 이용하여 부직포에 라디칼을 인위적으로 형성시켜(그라프트 중합) 양이온 또는 양이온을 교환할 수 있도록 제조된 섬유상의 흡착제로, 이온교환 섬유의 화학적 이온교환과 물리적 흡착 및 탈착반응이 동시에 발생되고, 활성탄/실리카켈 보다 흡착능력이 2~4배 높다. 또한 이온섬유의 재생기능을 이용하여 장기적 다양한 악취($H_2S$, $NH_3$, 아민계, 메르갑탄류, 알데히드 등) 및 유해가스(VOCs, NOx, SOx) 등을 95% 이상 제거할 수 있다.

• Journal of Biosystems Engineering
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• v.28 no.1
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• pp.53-58
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• 2003

This study was carried out to design, construct, and test a greenhouse monitoring system fur the environment and status of control devices in a greenhouse from a remote site using internet. The measuring items selected out of many environmental factors were temperature, humidity, solar radiation, CO$_2$, SOx, NOx concentration, EC, pH of nutrient solution, the state of control devices, and the image of greenhouse. The developed greenhouse monitoring system was composed of the network system and the measuring module. The network system consists of the three kinds of monitors named the Croup Monitor. the Client Monitor and the Server Monitor. The results of the study are summarized as follows. 1. The measuring module named the House Monitor. which is used to watch the state of the control device and the environment of the greenhouse, was developed to a embedded monitoring module using one chip microprocessor 2. For all measuring items. the House Monitor showed a satisfactory accuracy within the range of ${\pm}$0.3%FS. The House Monitors were connected to the Croup Monitor by communication method of RS-485 type and could operate under power and communication fault condition within 10 hours. The Croup Monitor was developed to receive and display measurement data received from the House Monitors and to control the greenhouse environmental devices. 3. The images of the plants inside greenhouse were captured by PC camera and sent to the Group Monitor. The greenhouse manager was able to monitor the growth state of plants inside greenhouse without visiting individual greenhouses. 4. Remote monitoring the greenhouse environment and status of control devices was implemented in a client/server environment. The client monitor of the greenhouse manager at a remote site or other greenhouse manager was able to monitor the greenhouse environment and the state of control devices from the Server Monitor using internet.