• 한국대기환경학회지
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• 제22권1호
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• pp.85-97
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• 2006

The PAMS data collected at four sites in Seoul metropolitan area in 2004 were analyzed using the positive matrix factorization (PMF) technique, in order to identify the possible sources and estimate their contributions to ambient VOCs. Ten sources were then resolved at Jeongdong, Bulgwang, Yangpyeong, and Seokmo, including vehicle exhaust, LPG vehicle, petroleum evaporation, coating, solvent, asphalt, LNG, Industry & heating, open burning, and biogenic source. The PMF analysis results showed that vehicle exhaust commonly contributed the largest portion of the predicted total VOCs mass concentration, more than $30\%$ at four sites. The contribution of other resolved sources were significantly different according to the characteristics of site location. In the case of Jeongdong and bulgwang located in urban area, various anthropogenic sources such as coating, solvent, asphalt, residual LPG, and petroleum evaporation contributed about $40\%$ of total VOCs mass. On the other hand, at yangpyeong and Seokmo located in rural and remote area, the portion of these anthropogenic sources was reduced to less than $30\%$ and the contribution of natural sources including open burning and biogenic source clearly observed. These results were considerably corresponding to the emission inventory investigated in this region.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제13권2호
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• pp.75-85
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• 2007

현재 시장에는 PVR, DVR, 캠코더 등과 같이 기록 가능 cd, dvd와 같은 광매체에 멀티미디어 스트림을 저장하고, 재생하는 많은 임베디드 시스템들이 많이 있다. 이 논문에서는 다양한 응용과 임베디드 시스템에서 사용할 수 있도록 명확한 구조와 문서를 가진 운영체제 독립적 광매체 API의 설계하고 공개 소스 형태로 구현한 내용을 기술한다. 연구에서는 실시간 광매체 기록을 위하여 ISO-9660 표준을 따르는 새로운 매체 레이아웃과 API를 제안하고 구현하였다. 또 개발된 API의 유용성을 검증하기 위해, 잘 알려진 CD 버닝 프로그램인 cdrecord를 대치할 수 있는 텍스트 응용 프로그램과 그래픽 응용 프로그램도 개발하였다. 모든 초기 개발은 Linux PC 환경에서 진행되었으며, 이후 pSOS를 운영체제로 하는 상용 임베디드 시스템에도 이식되었다.

• 한국대기환경학회지
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• 제17권2호
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• pp.133-145
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• 2001

The receptor modeling is one of the statistical methods to achieve reasonable air pollution strategies. The pur-pose of this study was to survey the concentration variability oi inorganic elements and ionic species in the PM-10 particles, to qualitatively characterize emission sources by an advanced algorithm called positive matrix factoriza-tion(PMF) as a receptor model that can strictly provide results in every loading matrix. A total of 254 samples was collected by a PM-10 high volume air sampler from Mar. 1997 to Feb. 1998 in Kyung Hee University at Suwon Campus. Fourteen chemical species(Zn, Cu, Fe, Pb, Al, Mn, $Na^{+}$, NH$_4$+, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$, $SO_4^{2-}$, $NO_{3}^{-}$, and $Cl^{-}$) were determined by AAS and IC methods. The study results showed that the average monthly concentration of PM-10 particles were 86.3$\mu\textrm{g}$/$\textrm{m}^3$ in March (maximum) and 28.5$\mu\textrm{g}$/$\textrm{m}^3$ in August(minimum), respectively. The concentrations of Na+, NH$_4$+, $K^{+}$ and $Cl^{-}$ in winter, $Mg^{2+}$, $Ca^{2+}$ and $NO_{3}^{-}$, in spring, and $SO_4^{2-}$ in summer showed the largest peak concentration for the respective season. Through and app-lication of a PMF program of Pm-10 concentration data of Suwon, 9 sources were qualitatively identified , such as incineration source, oil burning source, soil related source, open burning source automobile source, coal burning sources, secondary sulfate related source, and secondary nitrate related source.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2934-2939
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• 2008

We conducted a test of a direct burning of crude Jatropha oil (CJO) in a commercial boiler system. The fuel, crude Jatropha oil is not biodiesel which comes from transeterification process of bio oil, but it is pure plant oil. The higher heating value (HHV) of the CJO is 39.3 MJ/kg (9,380 kcal/kg) and is higher than that of a commercial heating oil, 37.9 MJ/kg. The kinematic viscosity of CJO is 36.2 mm2/s at $40^{\circ}C$ and 8.0 mm2/s at $100^{\circ}C$. The burner used in the test is a commercial burner for a commercial heatingoil and its capacity is 140 kW (120,000 kcal/h). We did a preliminary test whether the combustion is stable or not. The preliminary test was a kind of open air combustion test using the commercial burner with crude Jatropha oil. We found that the combustion can be stable if the crude Jatrophaoil temperature is higher than $90^{\circ}C$. We measured the flue gas concentration by using a gas analyzer. The NOx concentration is $80{\sim}100\;ppm$ and CO concentration is nearly 0 ppm at flue gas O2 concentration of 3.0 and 4.5%.

• Advances in environmental research
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• 제5권4호
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• pp.237-249
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• 2016

The management of municipal solid waste (MSW) is essential for every community; and, it is currently a major challenge in Nigeria. This paper provides an overview of the current MSW management trends in Nigeria and proposes new sustainable MSW management systems. Across Nigerian cities, MSW management is characterized by inefficient collection and transportation to disposal sites. Collection services do not reach some unplanned areas and slums due to poor street network. Even some planned areas are not reached by collection services. The informal sector contributes to waste collection, resource recovery and recycling; however, their activities are not recognized by the governments. Markets exist for recovered materials but more efforts need to be geared towards intensive recovery of materials and expansion of these markets. Despite the high proportion of putrescible matter in MSW, the only form of treatment commonly used currently is open burning for volume reduction. The high organic fraction presents a great opportunity for composting and anaerobic digestion. Ultimate disposal is currently done in open dumpsites. This needs to be upgraded to engineered landfills that are properly sited and adequately operated by well trained personnel. There is an emerging waste stream of concern, electronic-waste (e-waste), that requires urgent sustainable management as e-waste are currently co-disposed with other waste streams or burnt in the open posing detrimental health impacts.

• Journal of Biosystems Engineering
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• 제7권1호
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• pp.53-61
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• 1982

As an attempt to reduce the consumption of petroleum resources and to improve the performance of a kerosene engine, a series of experiments was conducted using several kinds of ethanol-kerosene blends under the various compression ratios. The engine used in this study was a single-cylinder, four-cycle kerosene engine having a compression ratio of 4.5. To investigate the feasibility of ethanol-kerosene blends in the original engine, kerosene and blends of 5-percent, 10-percent, and 20-percent-ethanol, by volume, with kerosene were used. And to investigate the feasibility of improving the performance of the kerosene engine, a portion of the cylinder head was cut off to increase the compression ratio up to 5.0 by reducing the combustion chamber volume. Kerosene and blends of 30-percent and 40-percent-ethanol, by volume, with kerosene were used for the modified engine with an increased compression ratio. Variable speed tests at wide-open throttle were also conducted at five speed levels in the range of 1000 to 2200 rpm for each compression ratio and fuel type. Volumetric efficiency, engine torque, and brake specific fuel consumption were determined, and brake thermal efficiency based on the lower heating values of kerosene and ethanol was calculated. The results obtained in the study are summarized as follows: A. Test with the original engine: (1) No abnormal conditions were found when burning ethanol-kerosene blends in the original engine. (2) Volumetric efficiency increased with ethanol concentration in blends. When burning blends of 5-percent, 10-percent, and 20-percent ethanol, by volume, with kerosene, average volumetric efficiency increased 1.6 percent, 2.6 percent, and 4.1 percent respectively, than when burning kerosene. (3) Mean engine torque increased 5.2 percent for 5-percent-ethanol blend, 9.3 percent for 10-percent-ethanol blend, and 11.5 percent for 20-percent-ethanol blend than for kerosene. Increase in engine torque when using ethanol-kerosene blends was due to the improved combustion characteristics of ethanol as well as an increase in volumetric efficiency. (4) Up to ethanol concentration of 20 percent, mean brake specific fuel consumption was nearly constant inspite of the difference in heating value between ethanol and kerosene. (5) Brake thermal efficiency increased 0.3 percent for 5-percent-ethanol blend, 3.8 percent for 10-percent-ethanol blend, and 6.8 percent for 20-percent-ethanol blend than for kerosene. B. Test with the modified engine with an increased compression ratio: (1) When burning kerosene, mean volumetric efficiency, engine torque, and brake thermal efficiency were somewhat lower than for the original engine. (2) Engine torque increased 15.1 percent for 30-percent-ethanol blend and 18.4 percent for 40-percent-ethanol blend than for kerosene. (3) There was no significant difference in brake specific fuel consumption regardless of ethanol concentration in blends. (4) Brake thermal efficiency increased 15.0 percent for 30-percent-ethanol blend and 19. 5 percent for 40-percent-ethanol blend than for kerosene.

• 대한화학회지
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• 제19권3호
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• pp.186-192
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• 1975

燃炭을 燃燒시킬 때 흙통중에서 一定量의 煉炭을 一定時間 燃燒를 持續시키기 위하여 空氣의 供給을 制限하게 되므로 많은 量의 一酸化炭素가 發生한다. 그러므로 一酸化炭素의 發生을 抑制하는 基本實驗으로 窒素, 酸素 및 一酸化炭素의 混合가스 및 炭素의 存在下에서 一酸化炭素의 燃燒率을 測定한 結果 一酸化炭素 燃燒溫度는 $700^{\circ}C$以上이고 空氣의 供給이 增加 할수록 一酸化炭素의 燃燒率이 改善됨을 알았다. 이러한 事實에서 燃燒時間의 延長과 一酸化炭素의 發生 抑制는 서로 相反되므로 두 가지 條件을 滿足시키는, 보다 效果的 燃燒裝置를 考案하였다. 즉 內徑이 다른 二重鐵筒으로 暖爐를 만들어 若干의 二次空氣가 에어자켓 下部에서 들어가 上部의 작은 구멍에서 나오게끔 하면 燃燒中인 煉炭과 熱交換되어 燃燒雰圍氣의 溫度는 低下된다. 따라서 燃燒時間은 길어지면 또 二重鐵筒을 通하여 上昇하는 豫熱空氣는 一酸化炭素의 再演燒를 促進시키게 되므로 一酸化炭素의 發生量은 흙통을 使用하였을때 보다도 1/20 程度로 減少된다.

• Journal of Plant Biology
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• 제17권4호
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• pp.18-22
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• 1974

Counts of herb stems were made with each systematic grid sized 10cm by 1300cm within six apparently homogeneous herb layers under the open young Japanese red pine, Pinus densiflora, stands. The stands had often been subjected to strong human interferences such as burning, cutting, grazing, and denuding since human settlement until the conservation scheme practiced in these stands for last decade. In addition, amounts of loss of ignition and field capacity were determined to detect soil heterogeneity among and within the stands. The values of information measure of diversity(H), and Hurlbert's probability of interspecfic encounter(Δ), obtained here do not show any consistent correlation. The amount of interspecific competetion(Δ1), the ratio of interspecific to intraspecific competetion(Δ4), Levin's niche breadth(Sh), and species evenness(V), increase, while the amount of intraspecific competetion decrease, as the soil factors become favorable. One stand examined does not follow the above trends, which is more young and shows strong within site heterogeneity of the soil factors. The stand includes pioneer species which is not detectable without detailed observation. It is argued that in stable or favorable environment more intense interspecific competetion and less intraspecific competetion might occur, but this situation does not necessarily always bring smaller niche breadth. In this connection, the results support Hurlbert's contention that the two components of diversity should be analyzed separately.

• 한국조리학회지
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• 제13권1호
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• pp.204-211
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• 2007

In order to develop a pot lid that would not overflow, three parts were created, each different in size. One cover (A") had a small hole (dia. 10 cm) for the vapor to escape (dia. about 2.5 mm). Another, cover A' had a medium-sized hole (dia. about 5 cm) for the vapor to escape. Cover A (dia. 300 mm, $120\;mm^H$) had a large hole (dia. 100 mm) for the vapor to escape. Because the new cover was partially open while soy paste solution cooking, it showed that it could not only prevent overflow, but also extend the burning approaching and salinity increase time, reducing both cooking time and the amount of energy necessary to cook.

• Journal of Advanced Marine Engineering and Technology
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• 제24권2호
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• pp.38-49
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• 2000

A diesel engine has been studied for many years to improve fuel economy and to reduce emissions as important factors governing the emission performance of diesel engines. This study addresses to swirl effects on combustion characteristics in a large diesel engine. The transport equations of flows and chemical reactions are given for fully compressible fluid. The simulations have been done for compression and expansion strokes and the results are given at several crank angles which are the angles at just before injection start, TDC, ATDC 90 and just before exhaust valve open. The results show that the strength of the swirl flow makes many effects on burning fuel and forming emissions.