• 한국환경과학회지
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• 제22권6호
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• pp.651-666
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• 2013

This study introduces a novel approach to the differentiation of two phenomena, Asian Dust and haze, which are extremely difficult to distinguish based solely on comparisons of PM10 concentration, through use of the Optical Particle Counter (OPC), which simultaneously generates PM10, PM2.5 and PM1.0 concentration. In the case of Asian Dust, PM10 concentration rose to the exclusion of PM2.5 and PM1.0 concentration. The relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration were below 40%, which is consistent with the conclusion that Asian Dust, as a prime example of the coarse-particle phenomenon, only impacts PM10 concentration, not PM2.5 and PM1.0 concentration. In contrast, PM10, PM2.5 and PM1.0 concentration simultaneously increased with haze. The relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration were generally above 70%. In this case, PM1.0 concentration varies because a haze event consists of secondary aerosol in the fine-mode, and the relative ratios of PM10 and PM2.5 concentration remain intact as these values already subsume PM1.0 concentration. The sequential shift of the peaks in PM10, PM2.5 and PM1.0 concentrations also serve to individually track the transport of coarse-mode versus fine-mode aerosols. The distinction in the relative ratios of PM2.5 and PM1.0 concentration versus PM10 concentration in an Asian Dust versus a haze event, when collected on a national or global scale using OPC monitoring networks, provides realistic information on outbreaks and transport of Asian Dust and haze.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1998년도 PROCEEDINGS OF THE 15TH KACG TECHNICAL MEETING-PACIFIC RIM 3 SATELLITE SYMPOSIUM SESSION 4, HOTEL HYUNDAI, KYONGJU, SEPTEMBER 20-23, 1998
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• pp.103-111
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• 1998

Au fine particle dispersed TiO2 film was prepared on silica glass substrate by sol-gel dip and firing process. The films were fabricated from the system of titanium tetraisoproxie-EtOh-HCl_H2O-hydrogen tetrachloroaurate(III) tetrahydrate. The conditions for the formation of the clear solution and dissolving high concentration of Au compound were examined. And a photoreduction process was adopted to control the size of gold metal particles. Phase evolution of matrix TiO2 and variation of Au particle with UV irradiation were investigated by XRDA, SEM, TEM and UV-visible spectrophotometer. And the effect of CPCl(Cetylpyridinium chloride monohydrate) as a dispersion agent was evaluated.

• 한국정밀공학회지
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• 제7권2호
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• pp.113-123
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• 1990

To study deleterious effects of contaminants contained in lubricating systems, the effects of fine alumina particle concentration and size on the critical failure load, friction and wear characteristic were examined on boundary lubrication condition using the four ball machine. The following conclusions are deduced: The abrasive is found to cause a transition from mild wear to severe wear at less severe conditions than with clean oil. In mild wear region the friction and wear increase with particle size and concentration, but in severe wear region do not exhibit any definite trend. In relation to film thinckness there is a threshold of particle size beyond which the failure load no longer decreases with particle size.

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권5호
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• pp.89-97
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• 2017

In this study, we evaluated effect of particle size on arsenic solid-state speciation and bioaccessibility in soils highly contaminated with arsenic from smelting and mining. Soils were partitioned into six particle size fractions ($2000-500{\mu}m$, $500-250{\mu}m$, $250-150{\mu}m$, $150-75{\mu}m$, $75-38{\mu}m$, <$38{\mu}m$), and arsenic solid-state speciation and bioaccessibility were characterized in each particle size fraction. Arsenic solid-state speciation was characterized via sequential extraction and XRD analysis, and arsenic bioaccessibility was evaluated by SBRC (Solubility Bioaccessibility Research Consortium) method. In smelter site soil, arsenic was mainly present as arsenic bound to amorphous iron oxides. Fine particle size fractions showed higher arsenic concentration, but lower arsenic bioaccessibility. On the other hand, arsenic in mine site soil showed highest concentration in largest particle size fraction ($2000-500{\mu}m$), while higher bioaccessibility was observed in smaller particle size fractions. Arsenic in mine site soil was mainly present as arsenolite ($As_2O_3$) phase, which seemed to affect the distribution of arsenic and arsenic bioaccessibility in different particle size fractions of the mine soil.

• 대기
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• 제27권1호
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• pp.29-40
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• 2017

The $PM_{10}$ and $PM_{2.5}$ particles over the Yellow Sea of Korea were collected by ship-borne observation during two cruises in spring, 2015. Their water-soluble ionic components such as $NH_4^+$, $Na^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $SO_4^{2-}$, $NO_3^-$, $Cl^-$, $F^-$, $CH_3COO^-$, $HCOO^-$, and $CH_3SO_3^-$ were analyzed, in order to examine the pollution characteristics of the secondary aerosol components. The comparative study of particle size distribution has resulted that $NH_4^+$, $nss-SO_4^{2-}$, $nss-Mg2+$, $nss-K^+$, $HCOO^-$, and $CH_3SO_3^-$ species mostly existed in fine particle mode. Meanwhile, nss-F-and sea-salt species were distributed in both fine and coarse particle mode, $NO_3^-$, $nss-Ca^{2+}$, $CH_3COO^-$ species were rich in coarse particle mode. The concentrations of secondary pollutants($nss-SO_4^{2-}$, $NO_3^-$, $NH_4^+$) increased in fine particles, and those of natural components ($nss-Ca^{2+}$, Sea-salt) increased in coarse particles. $NH_4^+$ exists as the form of $(NH_4)_2SO_4$ and $NH_4NO_3$, and mostly as $(NH_4)_2SO_4$ in fine particles. $NH_4NO_3$ has lower content compared to $(NH_4)_2SO_4$, and it mostly existed in fine particles at Yellow Sea I and in coarse particles at Yellow Sea II. The concentration ratios of $NO_3^-/nss-SO_4^{2-}$ for Yellow Sea I and Yellow Sea II were 0.52 and 0.16 in coarse particles, and they were 0.64 and 0.38 in fine particles, respectively, showing that the stationary source emissions were more important than mobile source emissions in Yellow Sea II (except Passage II-4).

• Asian Journal of Atmospheric Environment
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• 제4권1호
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• pp.55-61
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• 2010

The sensitivity of aerosol light extinction coefficient to the aerosol chemical composition change is estimated by (1) calculating the aerosol water content and chemical concentrations by a gas/particle equilibrium model and (2) calculating the aerosol light extinction coefficient by a Mie theory based optical model. The major chemical species are total (gas and particle phase) sulfuric acid, total nitric acid, and total ammonia which are based on the measurement data at Seoul and Gosan. At Seoul, since there were enough ammonia to neutralize both total sulfuric acid and total nitric acid, the dry ionic concentration is most sensitive to the variation of the total nitric acid level, while the total mass concentration (ionic concentration plus water content) and thus, the aerosol light extinction coefficient are primarily determined by the total sulfuric acid. At Gosan, since the concentration of ambient sulfuric acid was the highest among the inorganic species, sulfate salts determined aerosol hygroscopicity. Thus, both ionic and total mass concentration, and resultant aerosol light extinction coefficient are primarily determined by the sulfuric acid level.

• 대한환경공학회지
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• 제30권11호
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• pp.1111-1115
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• 2008

아산 호서대 지역에서 대기 중 미세먼지를 측정하여 PM$_{2.5}$와 PM$_{10}$의 이온성분과 중금속성분 분석을 통해 농도 특성을 분석하고 황사 발생에 따른 농도특성 변화를 관찰하였다. 황사시 미세먼지의 입경별 평균농도는 비황사시에 비해 큰 증가를 보였으나, PM$_{2.5}$ 비율은 79.7%에서 40.1%로 감소하였다. 이러한 원인은 2.1 $\mu$m를 기준으로 조대 입자와 미세 입자로 구분하여 질량농도를 분석한 결과 황사시 조대 입자가 크게 증가하여 PM$_{2.5}$ 비율이 상대적으로 낮아지기 때문인 것을 알 수 있었다. 황사시 이온 성분 농도의 변화는 미세입자 영역에서 큰 변화를 보이지 않았으나 조대입자 영역에서는 Ca$^{2+}$이온이 약 40배 정도 증가하였고 Na$^+$, SO$_4{^{2-}}$이온 순으로 높은 증가율을 나타내었다. 또한, 중금속 성분의 분석 결과 황사시 Mn, Fe, Zn, Al 순으로 증가폭이 컸으나 질량농도로 보았을 때 Al이 가장 큰 증가량을 보였다.

• 한국환경보건학회지
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• 제34권2호
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• pp.137-147
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• 2008

This study evaluated the effects of the human activity and outdoor air on concentrations of size-selective particulate matters (PM) by conducting a realtime measurement in classrooms and on roofs at 4 elementary schools, 3 middle schools and 3 high schools in Incheon City. PM concentrations featured repetitive pattern of increasing during break time (including lunch hours) and cleaning time while decreasing during class hours. This trend was more prominent with inhalable PM and PM10 than fine PMs (PM2.5, PM1.0). The indoor/outdoor (I/O) ratio of inhalable PM and PM10 exceeded 1 while that of fine PMs was close to or below 1. The PM2.5 (out)/PM10 (out) ratio stood at 0.59 (${\pm}0.16$) and the PM2.5 (in)/PM10 (in) ratio was 0.29 (${\pm}0.09$), suggesting that occupant activity had a greater effect upon coarse particles (PM10-PM2.5) than upon fine particles (PM2.5, PM1.0). The correlations between the indoor and the outdoor PM concentrations showed a stronger positive correlation for fine particles than that of coarse particles. The linear regression analysis of PM concentrations indoor and outdoor indicated a higher determinant coefficient ($r^2>0.9$), and consistency for fine particles than in case of coarse particles. In conclusion, the results of this study suggest that the indoor coarse particle concentration is more attributed to occupant activity and the indoor fine particle concentration is more influenced by outdoor air pollution.

• 한국대기환경학회지
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• 제9권3호
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• pp.222-229
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• 1993

Total suspended particles in the atmosphere were collected on the quartz fiber filters using an ANdersen Hi-volume air sampler from March 1989 to October 1989 and from June 1990 to February 1991, at Chung-Ang University in Seoul. A total amount of eight heavy metals (Cr, Zn, Cd, Pb, Fe, V, Ti, Mn) in total suspended particles were determined by ICP spectrophotometer. The annual arithmetic mean concentration of total suspended particle was 162.3$\mug/m^3$ and eight metals(Cr, Zn, Cd, Pb, Fe, V, Ti, Mn) were 11.6, 609.2, 3.5, 337.1, 2739.5, 15.1, 89.4 and 100.5ng/$m^3$, respectively. The concentration of total suspended particle was highest in the spring(343.7$\mug/m^3$) and lowest in the summer(91.8$\mug/m^3$). These heavy metals were distinguished into two groups in terms of their particle size distribution. The contents of first-group heavy metals (Fe, Ti, Mn) were increased in accordance with the growth of the particle size. The contents of the second-group ones such as Pb, Cd, V, and Zn, on the contrary, came to increase according as the particle size reduced. Statistical analysis indicated that there was a correlation between total suspended particle and Fe in coarse particles, and between total Suspended Particle and Zn, Pb in fine particle.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2005년도 국제학술대회
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• pp.311-314
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• 2005

To evaluate the acute effects of fine particles on pulmonary function, a longitudinal study was conducted. This study was carried out for the schoolchildren(3rd and 4th grades) living in Inner-Mongolia, China. 113 Chinese children were asked to record their daily levels of peak expiratory flow rate(PEPR) using portable peak flow meter(mini-Wright) for 40 days and 3 time everyday(12 April 2004 to 21 May 2004). The atmospheric concentration of fine particles in study area was also determined everyday during same period. The relationship between dailypeak expiratory flow rate(PEFR) and fine particle levels was analyzed using a mixed linear regression models including gender, age, height, the presence of respiratory symptoms, and daily average relative humidity as extraneous variables. The analysis showed that the increase of fine particle concentrations was negatively associated with the variability in PEPR. The IQR(inter-quartile range) increments of $PM_{10}$ or $PM_{2.5}(66.0{\mu}g/m^3$ and $118.9{\mu}g/m^3$, respectively) were also shown to be related with 1.422L/min(95% Confidence intervals: 0.270 ${\sim}$ 2.574) and 1.214L1min(95% Cl: 0.010 ${\sim}$ 2.418) decline in PEFR.