• 대한기계학회논문집B
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• 제30권2호
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• pp.177-185
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• 2006

This study aims deriving analysis the flow characteristic of kitchen hood system with using 3-D numerical analysis method and improving the system to expel pollutes more efficiently. To understand the flow characteristics of four models, this study only focuses on velocity field, temperature field, and concentration field varying with followings whether separation plate is set or not and the shapes of separation plates. The quantity of air, speed of exhaust fan and temperature and concentration of heating source are concerned as constant values. The three models having different shapes have one exhaust port and the model which has the vent at the closest position to where pollutes are generated is discovered to be the most efficient model. Compare to the initial model (having no separation plate), it was $1.4-1.9\%$ more efficient at temperature distribution and $9.4-11.9\%$ more at $CO_2$ concentration distribution.

• 도시과학
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• 제9권2호
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• pp.31-44
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• 2020

This study aims to analyze the relations among greenbelt, air pollution empirically in order to assess the environmental effects of the greenbelt in the Seoul metropolitan area, objectively. For this purpose, this study conducts an empirical analysis of impacts of greenbelt on urban air pollution using a multiple-regression model. The major findings are summarized as follows. As a result of an empirical analysis of the impacts of greenbelt on air pollution, it is found that the characteristics of the city have impacts on air pollution concentration. It is found that the population and employment are the causes of increases in CO and NO2 concentrations, and the number of employees in the manufacturers has impacts on increases of O3 and SO2, while power plants have impacts on PM10, CO and NO2. Intersections have impacts on O3 and SO2, while the areas of the roads have impacts on CO and NO2. In addition, as for the spatial distribution of air pollutants, it is found that CO and NO2 concentrations are relatively higher in the center of the Seoul metropolitan area, while PM10, O3 and SO2 concentrations are relatively higher in the suburbs. It is found that air pollution concentration is low in greenbelt zone. In the greenbelt zone, PM10, CO and SO2 concentrations are low.

• 환경위생공학
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• 제24권4호
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• pp.1-26
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• 2009

We conclude the following with air pollution data measured from city measurement net administered and managed in Gwangju for the last 7 years from January in 2001 to December in 2007. In addition, some major statistics governed by Gwangju city and data administered by Gwangju as national official statistics obtained by estimating the amount of national air pollutant emission from National Institute of Environmental Research were used. The results are as follows ; 1. The distribution by main managements of air emission factory is the following ; Gwangju City Hall(67.8%) > Gwangsan District Office(13.6%) > Buk District Office(9.8%) > Seo District Office(5.5%) > Nam District Office(3.0%) > Dong District Office(0.3%) and the distribution by districts of air emission factory ; Buk District(32.8%) > Gwangsan District(22.4%) > Seo District(21.8%) > Nam District(14.9%) > Dong District(8.1%). That by types(Year 2004~2007 average) is also following ; Type 5(45.2%) > Type 4(40.7%) > Type 3(8.6%) > Type 2(3.2%) > Type 1(2.2%) and the most of them are small size of factory, Type 4 and 5. 2. The distribution by districts of the number of car registrations is the following ; Buk District(32.8%) > Gwangsan District(22.4%) > Seo District(21.8%) > Nam District(14.9%) > Dong District(8.1%) and the distribution by use of car fuel in 2001 ; Gasoline(56.3%) > Diesel(30.3%) > LPG(13.4%) > etc.(0.2%). In 2007, there was no ranking change ; Gasoline(47.8%) > Diesel(35.6%) > LPG(16.2%) >etc.(0.4%). The number of gasoline cars increased slightly, but that of diesel and LPG cars increased remarkably. 3. The distribution by items of the amount of air pollutant emission in Gwangju is the following; CO(36.7%) > NOx(32.7%) > VOC(26.7%) > SOx(2.3%) > PM-10(1.5%). The amount of CO and NOx, which are generally generated from cars, is very large percentage among them. 4. The distribution by mean of air pollutant emission(SOx, NOx, CO, VOC, PM-10) of each county for 5 years(2001~2005) is the following ; Buk District(31.0%) > Gwangsan District(28.2%) > Seo District(20.4%) > Nam District(12.5%) > Dong District(7.9%). The amount of air pollutant emission in Buk District, which has the most population, car registrations, and air pollutant emission businesses, was the highest. On the other hand, that of air pollutant emission in Dong District, which has the least population, car registrations, and air pollutant emission businesses, was the least. 5. The average rates of SOx for 5 years(2001~2005) in Gwangju is the following ; Non industrial combustion(59.5%) > Combustion in manufacturing industry(20.4%) > Road transportation(11.4%) > Non-road transportation(3.8%) > Waste disposal(3.7%) > Production process(1.1%). And the distribution of average amount of SOx emission of each county is shown as Gwangsan District(33.3%) > Buk District(28.0%) > Seo District(19.3%) > Nam District(10.2%) > Dong District(9.1%). 6. The distribution of the amount of NOx emission in Gwangju is shown as Road transportation(59.1%) > Non-road transportation(18.9%) > Non industrial combustion(13.3%) > Combustion in manufacturing industry(6.9%) > Waste disposal(1.6%) > Production process(0.1%). And the distribution of the amount of NOx emission from each county is the following ; Buk District(30.7%) > Gwangsan District(28.8%) > Seo District(20.5%) > Nam District(12.2%) > Dong District(7.8%). 7. The distribution of the amount of carbon monoxide emission in Gwangju is shown as Road transportation(82.0%) > Non industrial combustion(10.6%) > Non-road transportation(5.4%) > Combustion in manufacturing industry(1.7%) > Waste disposal(0.3%). And the distribution of the amount of carbon monoxide emission from each county is the following ; Buk District(33.0%) > Seo District(22.3%) > Gwangsan District(21.3%) > Nam District(14.3%) > Dong District(9.1%). 8. The distribution of the amount of Volatile Organic Compound emission in Gwangju is shown as Solvent utilization(69.5%) > Road transportation(19.8%) > Energy storage & transport(4.4%) > Non-road transportation(2.8%) > Waste disposal(2.4%) > Non industrial combustion(0.5%) > Production process(0.4%) > Combustion in manufacturing industry(0.3%). And the distribution of the amount of Volatile Organic Compound emission from each county is the following ; Gwangsan District(36.8%) > Buk District(28.7%) > Seo District(17.8%) > Nam District(10.4%) > Dong District(6.3%). 9. The distribution of the amount of minute dust emission in Gwangju is shown as Road transportation(76.7%) > Non-road transportation(16.3%) > Non industrial combustion(6.1%) > Combustion in manufacturing industry(0.7%) > Waste disposal(0.2%) > Production process(0.1%). And the distribution of the amount of minute dust emission from each county is the following ; Buk District(32.8%) > Gwangsan District(26.0%) > Seo District(19.5%) > Nam District(13.2%) > Dong District(8.5%). 10. According to the major source of emission of each items, that of oxides of sulfur is Non industrial combustion, heating of residence, business and agriculture and stockbreeding. And that of NOx, carbon monoxide, minute dust is Road transportation, emission of cars and two-wheeled vehicles. Also, that of VOC is Solvent utilization emission facilities due to Solvent utilization. 11. The concentration of sulfurous acid gas has been 0.004ppm since 2001 and there has not been no concentration change year by year. It is considered that the use of sulfurous acid gas is now reaching to the stabilization stage. This is found by the facts that the use of fuel is steadily changing from solid or liquid fuel to low sulfur liquid fuel containing very little amount of sulfur element or gas, so that nearly no change in concentration has been shown regularly. 12. Concerning changes of the concentration of throughout time, the concentration of NO has been shown relatively higher than that of $NO_2$ between 6AM~1PM and the concentration of $NO_2$ higher during the other time. The concentration of NOx(NO, $NO_2$) has been relatively high during weekday evenings. This result shows that there is correlation between the concentration of NOx and car traffics as we can see the Road transportation which accounts for 59.1% among the amount of NOx emission. 13. 49.1~61.2% of PM-10 shows PM-2.5 concerning the relationship between PM-10 and PM-2.5 and PM-2.5 among dust accounts for 45.4%~44.5% of PM-10 during March and April which is the lowest rates. This proves that particles of yellow sand that are bigger than the size $2.5\;{\mu}m$ are sent more than those that are smaller from China. This result shows that particles smaller than $2.5\;{\mu}m$ among dust exist much during July~August and December~January and 76.7% of minute dust is proved to be road transportation in Gwangju.

• 터널과지하공간
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• 제8권1호
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• pp.8-16
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• 1998

The first purpose of this study is to verify the application of computer modelling to a enclosed space fire. The second one is to determine temperature distribution for the three different ventilation types in case of a enclosed space fire. The third one is to find out the ventilation direction and ventilation quantity to remove effectively heat and combustion products generated by a fire in variable air volume(VAV) system. Firstly, compared with experimental results of Lawrence Livermore National Laboratory(LLNL), numerical results show good agreements. Secondly, among three different ventilation types, the numerical analyses show the highest temperature distribution in occupied zone(up to 1.8 m from bottom) from firing moment to 100 sec. when supply ducts are placed in ceiling and extract duct is placed close to the bottom on side walls. This is due to disadvantageous position of extract duct in ventilating high temperature air which rise because of buoyancy force. Thirdly, this study finds out effective ventilation direction and ventilation quantity to remove heat and combustion products generated by a fire by using VAV system. $CO_2$ concentration is used as a fire fume removal index. As soon as a fire happens, ventilation direction is changed in order to gather and drive out fire fumes. In case of three times ventilation quantity of ordinary one, $CO_2$ concentration and temperature have begun to decrease at 120 sec. after firing, i.e.fire fumes have begun to be removed.

• 한국대기환경학회지
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• 제29권5호
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• pp.634-641
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• 2013

Condensing species behaviour downstream of a combustor was discussed with particle size distribution in this study. The effects of operating conditions in a biomass combustion facility, i.e. concentration of condensing species, temperature gradient, residence time and injection of adsorbents, on particle size distribution were investigated. Pyroligneous liquid which was completely vaporized at the temperature higher than $350^{\circ}C$ was used as a representative of condensing gaseous species. We found that particle size downstream of a combustor increased with increasing heating temperature (i.e. concentration of condensing species) and residence time. However, temperature gradient was not an important factor to control the particle size. The addition of $SiO_2$ precursor as an adsorbent could effectively prevent the particle formation by adsorbing condensing gaseous species on $SiO_2$ particles, and increased the particle size up to 300 nm, resulting in increasing particle removal efficiency in a conventional air pollution control device.

• 대한환경공학회지
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• 제30권2호
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• pp.225-233
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• 2008

지구 온난화에 대한 기여도가 50% 이상인 CO$_2$를 제어하려는 국제적 관심에 따라 CO$_2$ 제어에 대한 새로운 기술개발이 진행되고 있다. 따라서 본 연구에서는 PVA함량 및 소성온도에 따라 흡수제를 제조하여 고정층에서 CO$_2$ 흡수/재생 연속 실험 및 SO$_2$ 농도에 관한 실험을 수행하였다. 연구 결과, 비표면적은 832.79 m$^2$/g로 나타났고, SEM 측정결과 미세기공이 발달하여 건식흡수제로서의 가능성을 보였으며, CO$_2$ 흡수/재생 연속 실험에서는 SO$_2$ gas가 존재할 경우 부반응물질인 $Na_2SO_3$와 $Na_2SO_4$생성으로 CO$_2$ 흡수능 저하를 보였다.

• Macromolecular Research
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• 제12권2호
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• pp.233-239
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• 2004

We prepared thermally robust fully crosslinked poly(methyl methacrylate-co-divinyl benzene) ［poly(MMA-co-DVB)］microspheres successfully by precipitation polymerization in the absence of a stabilizing agent. The DVB concentration plays a pivotal role not only in the formation of the individually stable microspheres but also in the polymerization characteristics, including the particle size, the uniformity of size, the polymerization yield, and the thermal properties. The number-average diameter of the microspheres increased linearly, from 0.72 to 2.15 $\mu\textrm{m}$, and the particle size distribution became narrower, by elevating the uniformity from 1.35 to 1.12, as the DVB concentration increased from 20 to 75 mol%. In addition, the yield of the polymerization increased, from 73.4 to 98.6%, as the DVB concentration increased. Since the prepared particles possess fully crosslinked microstructures, no glass transition temperatures were observed, but all the samples prepared with DVB concentrations ranging from 20 to 75 mol% possess enhanced thermal properties. Based on the DSC and TGA data, the thermal stability of the mesospheres prepared by the precipitation polymerization is significantly improved as a result of crosslinking with DVB.

• 한국재료학회지
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• 제13권11호
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• pp.737-741
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• 2003

Polycrystalline $Ti_{l-x}$ $Co_{x}$ $O_2$thin films on $SiO_2$ (200 nm)/Si (100) substrates were prepared using liquid-delivery metalorganic chemical vapor deposition. Microstructures and ferromagnetic properties were investigated as a function of doped Co concentration. Ferromagnetic behaviors of polycrystalline films were observed at room temperature, and the magnetic and structural properties strongly depended on the Co distribution, which varied widely with doped Co concentration. The annealed $Ti_{l-x}$ $Co_{x}$ $O_2$thin films with $x\leq$0.05 showed a homogeneous structure without any clusters, and pure ferromagnetic properties of thin films are only attributed to the X$l-x_{l-x}$ $Co_{x}$X$O_2$phases. On the other hand, in case of thin films above x = 0.05, Co-rich clusters formed in a homogeneous $Ti_{l-x}$ $Co_{x}$ $O_2$phase, and the overall ferromagnetic (FM) properties depended on both FMTCO and FMCo. Co-rich clusters with about 10-150 nm size decreased the value of Mr (the remanent magnetization) and increased the saturation magnetic field.

• 한국농림기상학회지
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• 제24권4호
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• pp.275-284
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• 2022

기후변화에 따른 대기 온도 및 이산화탄소 농도의 상승은 농업 생산성에 큰 영향을 미칠 것으로 예상된다. RCP 8.5 시나리오에 따른 21세기말(2071~2100) 기후조건에서는 전 생육기간에 걸쳐 군락광합성이 크게 증가하였으나 이러한 효과가 종실 수량 증가로는 이어지지 않았다. 특히 높은 광합성능으로 인한 바이오매스의 증가는 분지 수 확보에 긍정적으로 작용하여 협수와 립수는 큰 변동이 없었던 반면 립중은 단독 고온 조건과 유사하게 현저히 감소하였다. 이는 등숙기간 중 고온에 의한 동화산물의 축적 및 전류 불량이 주요 요인으로 판단된다. 이러한 결과는 미래 기후 환경에서 종실 수량 감소가 협수와 립수 보다는 립중의 감소에 의한 것임을 의미한다. 이와 같은 결과들은 우리나라 남부지역에서 기후변화에 따른 콩 생육의 불확실성을 해소하고 피해 대책을 마련하기 위한 기초자료로써 유용하게 활용될 것으로 기대된다.

• 한국환경복원기술학회지
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• 제19권6호
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• pp.19-30
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• 2016

The projection of climate-related range shift is critical information for conservation planning of Korean fir (Abies koreana E. H. Wilson). We first modeled the distribution of Korean fir under current climate condition using five single-model species distribution models (SDMs) and the pre-evaluation weighted ensemble method and then predicted the distributions under future climate conditions projected with HadGEM2-AO under four $CO_2$ emission scenarios, the Representative Concentration Pathways (RCP) 2.6, 4.5, 6.0 and 8.5. We also investigated the predictive uncertainty stemming from five individual algorithms and four $CO_2$ emission scenarios for better interpretation of SDM projections. Five individual algorithms were Generalized linear model (GLM), Generalized additive model (GAM), Multivariate adaptive regression splines (MARS), Generalized boosted model (GBM) and Random forest (RF). The results showed high variations of model performances among individual SDMs and the wide range of diverging predictions of future distributions of Korean fir in response to RCPs. The ensemble model presented the highest predictive accuracy (TSS = 0.97, AUC = 0.99) and predicted that the climate habitat suitability of Korean fir would increase under climate changes. Accordingly, the fir distribution could expand under future climate conditions. Increasing precipitation may account for increases in the distribution of Korean fir. Increasing precipitation compensates the negative effects of increasing temperature. However, the future distribution of Korean fir is also affected by other ecological processes, such as interactions with co-existing species, adaptation and dispersal limitation, and other environmental factors, such as extreme weather events and land-use changes. Therefore, we need further ecological research and to develop mechanistic and process-based distribution models for improving the predictive accuracy.