• 대한환경공학회지
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• 제30권3호
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• pp.302-313
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• 2008

본 연구는 포항지역 대기 중 PM$_{2.5}$의 물리 화학적 성분들의 농도분포특성을 파악하여 PM$_{2.5}$에 대한 배출원 기여도를 정량적으로 추정하고 PM$_{2.5}$농도 변동에 영향을 미치는 배출원을 알아보고자 하였다. 시료채취지점은 포항지역 내의 대조적인 두 지점인 공업지역과 주거지역에서 각 1개 지점을 선정하였다. 시료채취는 2003년 3월부터 12월에 걸쳐서 계절별 10$\sim$15일 동안 고용량공기시료채취기를 이용하여 24시간 연속 채취였다. PM$_{2.5}$ 시료에 함유된 화학성분들은 산추출하여 ICP와 이온크로마토그래피로 분석하였다. PM$_{2.5}$의 전체평균은 공업지역이 36.6 $\mu$g/m$^3$, 주거지역에서 30.6 $\mu$g/m$^3$로 나타났다. 계절별로는 두 지점 모두 봄철에 가장 높은 농도를 보이고 있으며 다음으로 겨울철, 가을철, 여름철의 순으로 나타났다. 두 측정지점에서 PM$_{2.5}$ 중 가장 많이 함유된 화학성분들은 이차생성입자를 형성하는 성분인 NO$_3^-$, SO$_4^{2-}$으로 나타났으며 각각의 농도는 공업지역에서 4.2 및 8.6 $\mu$g/m$^3$, 주거지역에서 3.7 및 6.9 $\mu$g/m$^3$로 나타났다. 반면, 공업지역에서는 Fe, Mn, Cr 등의 금속성분 농도가 주거지역에 비해 상당히 높게 나타나 공업지역이 철강산업의 영향을 반영하고 있는 것으로 추측된다. 포항지역 대기 중 PM$_{2.5}$의 농도 변동에 미치는 주요 영향인자를 파악하기 위하여 주성분 분석 및 다중회귀분석을 실시한 결과, 공업지역과 주거지역에서 가장 중요한 변수는 도로 비산먼지와 이차생성입자인 것으로 나타났으며, 이들 변수의 변동이 전체 PM$_{2.5}$ 농도변동에 가장 큰 영향을 미친다는 것을 알 수 있었다. 또한 포항지역 PM$_{2.5}$에 대한 주요 발생원의 기여도를 평가하기 위하여 CMB 모델링을 수행한 결과 공업지역의 경우 기여도가 큰 발생원은 토사 및 도로상의 비산먼지로 나타났고 그 다음으로 이차생성입자, 자동차, 해염입자, 금속산업의 순을 보였으며 주거지역도 이와 유사한 양상을 보였다. 이와 같은 결과를 토대로 국내에서 측정된 먼지시료를 대상으로 CMB 모델링 수행 시 그 적용한계성과 문제점 등을 고찰하였다.

• 한국대기환경학회지
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• 제28권5호
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• pp.538-555
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• 2012

The purpose of this study was to understand $PM_{2.5}$ chemical characteristics on the Suwon/Yongin area and further to quantitatively estimate $PM_{2.5}$ source contributions. The $PM_{2.5}$ sampling was carried out by a high-volume air sampler at the Kyung Hee University-Global Campus from November, 2010 to October, 2011. The 40 chemical species were then analyzed by using ICP-AES(Ag, Ba, Cr, Cu, Fe, Mn, Ni, Pb, Si, Ti, V and Zn), IC ($Na^+$, $K^+$, $NH_4{^+}$, $Mg^{2+}$, $Ca^{2+}$, $NO_3{^-}$, ${SO_4}^{2-}$ and $Cl^-$), DRI/OGC (OC1, OC2, OC3, OC4, OP, EC1, EC2 and EC3) and GC-FID (acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[a] pyrene, indeno[1,2,3-cd] pyrene, benzo[g,h,i]perylene and dibenzo[a,h,]anthracene). When applying PMF model after performing proper data treatment, a total of 10 sources was identified and their contributions were quantitatively estimated. The average contribution to $PM_{2.5}$ emitted from each source was determined as follows; 26.3% from secondary aerosol source, 15.5% from soil and road dust emission, 15.3% from vehicle emission, 15.3% from illegal biomass burning, 12.2% from incineration, 7.2% from oil combustion source, 4.9% from industrial related source, and finally 3.2% from coal combustion source. In this study we used the ratios of PAHs concentration as markers to double check whether the sources were reasonably classified or not. Finally we provided basic information on the major $PM_{2.5}$ sources in order to improve the air quality in the study area.

• Asian Journal of Atmospheric Environment
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• 제10권1호
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• pp.51-56
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• 2016

Particulate matter (PM) in the atmosphere has wide-ranging health, environmental, and climate effects, many of which are attributed to fine-mode secondary organic aerosols. PM concentrations are significantly enhanced by primary particle emissions from traffic sources. Recently, in order to reduce $CO_2$ and increase fuel economy, gasoline direct injected (GDI) engine technology is increasingly used in vehicle manufactures. The popularization of GDI technique has resulted in increasing of concerns on environmental protection. In order to better understand variations in chemical composition of particulate matter from emissions of GDI vehicle versus a port fuel injected (PFI) vehicle, a high time resolution chemical composition of PM emissions from GDI and PFI vehicles was measured at facility of Transport Pollution Research Center (TPRC), National Institute of Environmental Research (NIER), Korea. Continuous measurements of inorganic and organic species in PM were conducted using an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The HR-ToF-AMS provides insight into non-refractory PM composition, including concentrations of nitrate, sulfate, hydrocarbon-like and oxygenated organic aerosol, and organic mass with 20 sec time resolution. Many cases of PM emissions during the study were dominated by organic and nitrate aerosol. An overview of observed PM characteristics will be provided along with an analysis of comparison of GDI vehicle versus PFI vehicle in PM emission rates and oxidation states.

• 한국대기환경학회지
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• 제25권4호
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• pp.275-288
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• 2009

The Korean government strengthened the environmental polices to manage and enhance Metropolitan Area air quality, and also has enforced "Special Act on Seoul Metropolitan Air Quality Improvement (SASMAQI)" issued in Dec. 2004. Recently government expanded the Seoul Metropolitan Air Quality Management District (SMAQMD) to the outskirts satellite cities of Seoul area through the "Revised Law Draft of SASMAQI". The SMAQMD has been alloted the allowable emission loads to the local governments on the basis of the carrying $PM_{10}$ capacity. However, in order to establish the effective air quality control strategy for $PM_{10}$, it is necessary to understand the corresponding sources which have a potential to directly impact ambient $PM_{10}$ concentration. To deal with the situations, many receptor methodologies have been developed to identify the origins of pollutants and to determine the contributions of sources of interests. The objective of this study was to extensively identify $PM_{10}$ sources and to estimate their contributions at the metropolitan area. $PM_{10}$ samples were simultaneously collected at the 3 semi-industrialized local cities in the Seoul metropolitan area such as Hwasung-si, Paju-si, and Icheon-si sites from April 15 to May 31, 2007. The samples collected on the teflon membrane filter by one $PM_{10}$ cyclone sampler were analyzed for trace metals and soluble ions and samples on the quartz fiber filter by another sampler were analyzed for OC and EC. Source apportionment study was then performed by using a positive matrix factorization (PMF) receptor model. A total of 6 sources were identified and their contributions were estimated in each monitoring site. Contribution results on Hwasung, Paju, and Icheon sites were as follows: 33%, 27%, and 27% from soil source, 26%, 26%, and 21% from secondary aerosol source, 11%, 11%, and 12% from biomass burning, 12%, 6%, and 5% from sea salt, 7%, 15%, and 19% from industrial related source, and finally 11%, 15%, and 16% from mobile and oil complex source, respectively. This study provides information on the major sources affecting air quality in the receptor sites and thus it will help to manage the ambient air quality in the metropolitan area by establishing reasonable control strategies, especially for the anthropogenic emission sources.

• 에너지공학
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• 제24권4호
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• pp.42-47
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• 2015

국내에 유통되는 자동차용휘발유의 산소함량은 2.3 wt % 이하로 규제하고 있는 반면, 유럽 및 세계연료헌장(WWFC)에서는 2.7 wt % 이하로 규제하고 있다. 산소함량을 결정짓는 함산소물질은 내연기관 내에서 연료의 연소를 보조하여 옥탄가를 상승시키고, 불완전연소로 야기되는 CO, HC와 같은 배출가스 저감에 효과가 있는 것으로 보고되고 있다. 2000년대 이전 미국, 유럽 등에서 자동차용휘발유의 산소함량 변화에 따른 차량적용 평가연구가 추진된 바 있으나, 발전하고 있는 연료품질, 자동차기술현황을 반영한 국내실정의 연구는 많지 않다. 본 연구에서는 자동차용휘발유의 산소함량을 변화시킨 3종의 연료를 GDI, MPI 연료 분사 방식의 차량에 적용하여 비교 평가 하였다. 결과적으로 산소함량 변화에 따른 연비, 배출가스의 변화는 유사하였지만, GDI 엔진에서 산소함량이 증가할수록 PN은 감소하는 경향을 나타내었다.

• 한국진공학회지
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• 제17권4호
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• pp.311-316
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• 2008

저에너지(수 eV) 양전자 빔을 이용하여 도체나 반도체의 표면/계면의 물리화학적 특성 분석에 독특한 유용성이 보고 되고 있다. 기존의 표면 분석법에 비해 표면의 선택도가 향상되어 반도체 소자의 박막 두께가 얇아지는 최신기술에 적합한 분석법으로 주목을 받고 있다. 물질표면에 조사된 저에너지 양전자는 표면 근처의 image potential에 포획이 되어 표면에 있는 전자들과 쌍소멸하며 Auger 전자를 방출한다. 표면으로부터 방출된 Auger 전자의 에너지를 측정함으로 원자의 화학적 구별이 가능하므로 검출기의 에너지 분해도가 중요하다. 기존의 ExB 형태의 에너지 측정기는 분해도가 $6{\sim}10\;eV$ 정도이고 특정한 에너지 영역만을 일정시간 스캔하여 스펙트럼을 측정하므로 측정시간이 길어진다는 단점이 있다. 반면에 Time-Of-Flight(TOF) 시스템은 방출되는 전자들의 에너지를 동시에 검출하므로 측정시간이 단축되어 측정 효율이 향상된다. 에너지 분해도를 높이기 위해서는 측정하고자 하는 전자의 진행거리를 길게 할수록 좋으나, 공간적 제약을 고려한 reflected TOF 시스템과 retarding tube을 이용한 linear TOF 시스템의 에너지 분해도를 이론적으로 시뮬레이션하였다.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.1-26
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• 1994

The purpose of this study was to investigate the dissolution components during corrosion of amalgams and to identify surface corrosion products in the modified Fusayama artificial saliva. Four type of amalgam alloys were used: low copper lathe cut amalgam alloy (Cavex 68), low copper spherical amalgam alloy (Caulk Spherical Alloy), high copper admixed amalgam alloy (Dispersalloy) and high copper single composition amalgam alloy (Tytin). Each amalgam alloy and Hg were triturated according to the manufacturer's direction by means of mechanical amalgamator (Capmaster, S.S.White), and then the triturated mass was inserted into the cylindrical metal mold which was 10mm in diameter and 2.0mm in height and condensed with compression of 150kg/$cm^2$ using oil pressor. The specimens were removed from the mold and stored at room temperature for 7 days and cleansed with distiled water for 30 minutes in an ultrasonic cleaner. The specimens were immersed in the modified Fusayama artificial saliva for the periods of 1 month, 3 months and 6 months. The amounts of Hg, Cu, Sn and Zn dissolved from each amalgam specimen immersed in the artificial saliva for the periods of 1 month, 3 months and 6 months were measured using Inductivity Coupled Plasma Atomic Emission Spectrometry (ICPQ-1000, Shimadzu, Japan) and amount of Ag dissolved from amalgam specimen was measured using Atomic Absorption Spectrophotometry (Atomic Absorption/Flame emission spectrophotometer M-670, Shimadzu, Japan). A surface corrosion products of specimens were analysed using Electron Spectroscopy Chemical Analyser (ESCA PHI-558, PERKIN ELMER, U.S.A.). The secondary image and back scattered image of corroded surface of specimens was observed under the SEM, and the corroded surface of specimens was analysed with the EDX. The following results were obtained. 1. The dissolution amount of Cu was the most in high copper admixed amalgam(Dispersalloy) and the least in high copper single composition amalgam(Tytin). 2. Sn and Zn were dissolved during all the experiment periods, and dissolution amounts were decreased as the time elapsed. 3. Initial surface corrosion products were ZnO and SnO. 4. Corrosion of ${\gamma}$ and ${\gamma}_2$ phase in low copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in low copper spherical amalgam(Caulk Sperical Alloy). 5. Corrosion of ${\gamma}$ and $\eta$' phase in high copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in high copper admixed amalgam(Dispersalloy). 6. Sn-Cl was produced in the subsurface of low copper amalgams and high copper admixed amalgam.

• 한국환경교육학회지:환경교육
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• 제3권1호
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• pp.130-140
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• 1992

The purpose of this study was to survey the trends of waste products in schools, its gathering and disposal, identification of problems and to analyze its disposal. Moreover, this study was aimed at basic suggestions about the establishment and plans of waste environmental education. 98 public primary and secondary schools were surveyed in Seoul during the month of March and April, 1991. Information was collected from each educational association by random sampling. Questionaries were used for this survey. To understand the disposal status of school waste and its reforms, this study surveyed the amount of waste by products, their origin and analyzed the disposal by type, one number of schools and teachers involved. The dump sited and disposal methods of school waste, its problems, and the status of school waste educations were researched, and ideal disposal methods and plans for waste education were suggested. The results were as follows. 1. The School's trash was produced by followings: paper, vinyle plastics, food, woods, metals, ceramics, glass, bottles, and ash from the heating system. The biggest cause of the school's waste as shown by the survey was a lack of environmental awareness(39.8%). The second biggest was the use of a one time use of disposable paper products(27.6%). 2. Waste collection by different grade levels were proven to be important but as you move from elementary to high school, the waste collecting operation decreased, in this connection between the students and waste collection itself it was significant on the other hand the teachers were not working as significant variables. 3. Of the school that collected waste 69.5 percent of the schools separately grouped common waste and recyclable waste. 25 schools(42.4%) received improvement on their environmental awareness of trash collection through this method. 4. From the number of disposal sites in surveyed schools, it was determined that the education of the necessity for separation of waste was performed in vain and accordingly the should require a real education in the future. 5. Regarding the method of disposal of waste the survey indicated that the #1 method of disposal was partial burning and the remains carried to a dump site by others(35,7%). In elementary schools the entire waste was taken by individuals to a dump site (33.3%). In high schools partial burning and then transported by individuals #1 in our survey(50%). 6. Relative to the problem of the treatment to waste, the emission of smoke from the burning was considered to be the #1 priority in our survey (62.3%) the problem of trash collection being delayed was 52.1%(1in our survey). 7. The present situation of environmental education of waste us lacking. Under present circumstances, the practice of public announcements for improvement and waste-paper collection has been going on vigorously but lacking in education as to the preparation of compositions for students the themes of public exhibitions, the organizing of voluntary associations should be part of the education system to reinforce student's awareness of proper waste disposal. 8. The most economical alternative for disposal was recycling usable waste or combustible material through a variety of education we can therefore educate students bring this education to their homes public servants will also be able to benefit in the waste disposal process with proper education. In conclusion we should intensify the systemical organization and the education of our waste disposal for a better environment.

• 한국대기환경학회지
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• 제31권1호
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• pp.28-40
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• 2015

To investigate the seasonal variations of carbonaceous aerosol in Daejeon, OC (organic carbon), EC (elemental carbon) and WSOC (water soluble organic carbon) in $PM_{2.5}$ samples collected from March 2012 to February 2013 were analyzed. $PM_{2.5}$ concentrations were estimated by the sum of organic matter ($1.6{\times}OC$), EC, water-soluble ions ($Na^+$, $NH_4{^{+}}$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, $SO_4{^{2-}}$, $NO_3{^{-}}$). The estimated $PM_{2.5}$ concentrations were relatively higher in winter ($29.50{\pm}12.04{\mu}g/m^3$) than those in summer ($13.72{\pm}6.92{\mu}g/m^3$). Carbonaceous aerosol ($1.6{\times}OC+EC$) was a significant portion (34~47%) of $PM_{2.5}$ in all season. The seasonally averaged OC and WSOC concentrations were relatively higher in winter ($6.57{\times}3.48{\mu}gC/m^3$ and $4.07{\pm}2.53{\mu}gC/m^3$ respectively), than those in summer ($3.07{\pm}0.8{\mu}gC/m^3$, $1.77{\pm}0.68{\mu}gC/m^3$, respectively). OC was correlated well with WSOC in all season, indicating that they have similar emission sources or formation processes. In summer, both OC and WSOC were weakly correlated with EC and also poorly correlated with a well-known biomass burning tracer, levoglucosan, while WSOC is highly correlated with SOC (secondary organic carbon) and $O_3$. The results suggest that carbonaceous aerosol in summer was highly influenced by secondary formation rather than primary emissions. In contrast, both OC and WSOC in winter were strongly correlated with EC and levoglucosan, indicating that carbonaceous aerosol in winter was closely related to primary source such as biomass burning. The contribution of biomass burning to $PM_{2.5}$ OC and EC, which was estimated using the levoglucosan to OC and EC ratios of potential biomass burning sources, was about $70{\pm}15%$ and $31{\pm}10%$, respectively, in winter. Results from this study clearly show that $PM_{2.5}$ OC has seasonally different chemical characteristics and origins.

• 한국입자에어로졸학회지
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• 제16권1호
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• pp.19-30
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• 2020

The organic carbon in the ambient particulate matter (PM) is divided into primary organic carbon (POC) and secondary organic carbon (SOC) by their formation way. To regulate PM effectively, the estimation of the amount of POC and SOC separately is one of important consideration. Since SOC cannot be measured directly, previous studies have evaluated determination of SOC by the EC tracer method. The EC tracer method is a method of estimating the SOC value from calculating the POC by determining (OC/EC)pri which is the ratio of the measured values of OC and EC from the primary combustion source. In this study, three different ways were applied to OC and EC concentrations in PM_2.5 measured at Seoul for determining (OC/EC)pri: 1) the minimum value of OC/EC ratio during the measurement period; 2) regression analysis of OC vs. EC to select the lower 5-20% OC/EC ratio; 3) determining the OC/EC ratio which has lowest correlation coefficient value (R²) between EC and SOC which is reported as minimum R squared method (MRS). Each (OC/EC)pri ratio of three ways are 0.35, 1.22, and 1.77, respectively from the 1 hourly data. We compared the (OC/EC)pri ratio from 1hourly data with 24 hourly data and revealed that (OC/EC)pri estimated from 24 hourly data had twice larger than 1hourly data due to the low time resolution of sampling. We finally confirmed that the most appropriate value of (OC/EC)pri is that calculated by a regression analysis of 1 hourly data and estimated SOC amounts at PM_2.5 of the Seoul atmosphere.