• 한국결정성장학회지
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• 제11권2호
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• pp.78-84
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• 2001

The binary forsterite($Mg_2SiO_4$)/spinel ($MgAl_2O_4$) system, a possible refractory for industrial applications, is investigated for their density and grain growth the same firing conditions as the each component material between $1400^{\circ}C$ and $1700^{\circ}C$ ($1650^{\circ}C$). The forsterite grain growth exponent is established to be equal to 5 for all compositions within this binary system. Generally; the spinel addition to forsterite inhibited the forsterite grain growth. The activation energies for the forsterite grain growth of the eight compositions(weight ratio of forsterite/spinel) within the binary system are determined to be: 952$\pm$79(95/5), 363$\pm$37(90/10), 219$\pm$21(80/20), 220$\pm$44(70/30), 112$\pm$16(50/50), 112$\pm$23(30/70), 198$\pm$26(10/90), and 121$\pm$12(5/95) KJ/mol. The more forsterite is contained within the binary system, the higher value the activation energy for forsterite grain growth. It is considered that the forsterite grain growth at the higher forsterite compositions are more inhibited by spinel than that of the lower forsterite compositions.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.435-437
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• 2003

In order to investigate processes and factors controlling the chemical and isotopic compositions of the Han River, seasonal studies were carried out. The North Han River was much lower in the concentrations of total dissolved solids (TDS), dissolved inorganic carbon (DIC) and major ions than the South Han River, but higher in $SiO_2$ concentration, $\delta$$^{34}$ $S_{so4}$ value and $^{87}$ Sr/$^{86}$ Sr ratio. This indicates that the chemical and isotopic compositions of the Han River were strongly controlled by the geology of their drainage basins: silicate rocks in the North Han River and carbonate rocks in the South Han River. The $\delta$$^{34}$ $S_{so4}$ values were relatively higher in the North Han River (5.90$\pm$1.46$\textperthousand$)) than in the South Han River (3.48$\pm$0.73$\textperthousand$). This implies that dissolved S $O_{4}$$^{2-}$ in the North Han River might be mostly derived from deposition of atmospheric sulfates, whereas in the South Han River from oxidation of sulfide minerals in the abandoned poly-metallic deposits and the coal-bearing sedimentary rocks distributed over the upstream as well as deposition of atmospheric sulfates. The $^{87}$ S $r^{86}$ Sr ratios in the North Han River were distinctly higher than those in the South Han River, reflecting water-rock interaction with different rock types.pes.

• 분석과학
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• 제30권4호
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• pp.182-193
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• 2017

In order to examine the variation characteristics of chemical compositions in relation to the inflow pathways of Asian dust, $PM_{10}$ and $PM_{2.5}$ aerosols were collected at Gosan site of Jeju Island during the Asian dust days between 2010 and 2015, and their chemical compositions were analyzed. The mean mass concentrations of $PM_{10}$ and $PM_{2.5}$ during Asian dust days were $130.0{\pm}90.2$ and $38.2{\pm}24.7{\mu}g/m^3$, respectively. The composition ratios of major secondary pollutants ($nss-SO_4{^{2-}}$, $NH_4{^+}$, $NO_3{^-}$) were high as 53.7 % for $PM_{10-2.5}$ and 90.6 % for $PM_{2.5}$. When the Asian dusts had been transported to the Korean Peninsula via Loess Plateau of central China, the concentrations of $nss-Ca^{2+}$, $NH_4{^+}$, $nss-SO_4{^{2-}}$, and $NO_3{^-}$ increased more noticeably. Whereas in case when the inflow pathways of Asian dust had been through the Bohai bay, the concentrations of the crustal species such as Al, Fe, and Ca were relatively high in coarse particles. The atmospheric aerosols were acidified largely by sulfuric and nitric acids. They were neutralized mainly by calcium carbonate in coarse particle mode passed through Manchuria area, but by ammonia in fine particle mode passed through Loess plateau and Bohai bay. Ammonium salts are assumed to exist as ammonium sulfate and ammonium nitrate in coarse particles, but mostly as ammonium sulfate in fine particles.

• 한국입자에어로졸학회지
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• 제19권4호
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• pp.129-144
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• 2023

The PM_1.0 and PM_2.5 samples were collected synchronously using a single channel particulate sampler equipped with PM_1.0 and PM_2.5 cyclones, respectively, and seasonal mass concentration and chemical composition of PM_1.0 and PM_2.5 were quantified in Seoul and Gwangju in 2021-2022. The mass concentrations of PM_1.0 and PM_2.5 were 17±11 and 22±14 ㎍/m³ in Seoul, and 16±9 and 19±12 ㎍/m³ in Gwangju, respectively. The average ratios of PM_1.0/PM_2.5 were 83±16% in Seoul and 83±7% in Gwangju. The chemical compositions of PM_1.0 and PM_2.5 were similar at both sites with OC component being the most dominant, and NO₃^- increasing from summer to winter, while, the difference of chemical distribution at the two sites was most distinct in the autumn. Gwangju showed a higher proportion of OC and a lower proportion of NO₃^- compared to Seoul during the autumn. Both sites appear to reflect their urban characteristics, with Gwangju also reflecting the impact of biomass combustion as a part of rural activities.

• 한국환경과학회지
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• 제26권5호
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• pp.591-600
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• 2017

This study was carried out to elucidate the chemical compositions of water-soluble inorganic ions in $PM_{10}$ and $PM_{2.5}$ aerosols collected during summer and winter in downtown Jejusi city. The ratios of $NO_3^-$ to the total mass of ionic species in $PM_{10}$ and $PM_{2.5}$ aerosols largely increase in winter compared to summer, while $SO_4^{2-}$ ratios in both aerosols appear to follow the opposite trend. Moreover, concentrations of $Na^+$, $Mg^{2+}$, $Ca^{2+}$ and $Cl^-$ in $PM_{10}$ and $PM_{2.5-10}$ aerosols are higher in winter than in summer. The nitrate concentrations in $PM_{10}$ and $PM_{2.5}$ aerosols increase with an identical increase in excess ammonium during winter, however, nitrate formation during summer is not important owing to ammonium-poor conditions.

• 한국환경과학회지
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• 제25권6호
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• pp.865-875
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• 2016

In this study, mass concentrations and chemical compositions of $PM_{2.5}$, including water-soluble ions and elements were determined at the 1,100 m-highland of Mt. Hallasan in Jeju Island across four seasons from August 2013 to August 2014. The average mass concentration of $PM_{2.5}$ was $12.5{\pm}8.41{\mu}g/m^3$ with 45.8% of the contribution from eight water-soluble ionic species. Three ionic species ($SO{_4}^{2-}$, $NH{_4}^+$, and $NO{_3}^-$) comprised 96.2% of the total concentration of ions contained in $PM_{2.5}$ and were the dominant ions, accounting for 43.5% of the $PM_{2.5}$ mass at Mt. Hallasan. On the basis of the mass concentration level, seasonal variation, enrichment factor, and relationship among elements, we can presume that Mg, K, Ca, Mn, Fe, Co, Sr, Ba, Nd, and Dy originated mainly from crust or soil and that V, Cr, Ni, Cu, Zn, As, Cd, and Pb were significantly enriched in $PM_{2.5}$ owing to the effects of the anthropogenic emissions. These results and the local distribution of emission sources and topographic characteristics near this sampling site suggest that the compositions of $PM_{2.5}$ collected at the 1100 m-highland of Mt. Hallasan were largely influenced by inflow from outside of Jeju Island.

• 한국식품과학회지
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• 제51권3호
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• pp.258-262
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• 2019

마늘의 일부 품종에서 화학적 조성 및 생물학적 특성이 조사되었지만 현재 고아라 마늘의 주요 성분 및 생리활성에 대한 조사는 부족한 현실이다. 2012년 품종으로 등록된 고아라 마늘의 주요성분 및 생리활성을 측정하기 위하여 서귀포, 담양 및 남해에서 재배하여 비교하였다. 재배된 마늘 성분을 분석한 결과 서귀포에서는 황 관련 물질(알리인과 피루베이트 총량)과 항균 활성이 우수했으며 남해에서는 페놀 함량과 환원당 함량이 풍부하였으며, 담양에서는 총 플라보노이드 함량이 높게 나타났다. 위의 결과를 고려할 때 재배 지역 간에는 차이가 있었지만 고아라 마늘은 지금까지 보고된 다른 마늘 품종과 비슷하게 주요 성분함량과 생리 활성을 보여주었다. 이러한 연구 결과는 지역 농민, 유통 업자 및 소비자에게 유용한 정보가 될 것이다.

• 한국대기환경학회지
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• 제16권4호
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• pp.309-316
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• 2000

Chemical compositions of air pollutants with fine particles (<2.5 ${\mu}{\textrm}{m}$, PB2.5) were evaluated at background site. Kangwha. in Korea during the winter season. The data set was obtained for seventeed days with 24-hour sampling from December 11 to 16, 1996 and from January 9 to 1997. The chemical species have been measured {{{{ {SO }`_{4 } ^{2- } }}}}, {{{{ { NO}`_{3 } ^{- } }}}}, {{{{ { NH}`_{4 } ^{+ } }}}}. OC and EC in the particulate phase, NH3 HNO3, HCl and SO2 in the gas phase using the three stage filter pack method. Mean concentration ($\mu\textrm{g}$/m3) of this study were : 35.42 for PM2.5 8.78 for organic carbon (OC) 7.25 for nss {{{{ {SO }`_{4 } ^{2- } }}}}, 4.94 for {{{{ { NO}`_{3 } ^{- } }}}}, 3.58 for {{{{ { NH}`_{4 } ^{+ } }}}} and 1.48 for elemental carbon (EC) respectively. Contributive rates of major particulate components in PM2.5 were OC (25%) nss- {{{{ {SO }`_{4 } ^{2- } }}}}(20%) ,{{{{ { NO}`_{3 } ^{- } }}}}(14%) {{{{ { NH}`_{4 } ^{+ } }}}}(10%) and EC (4%) respectively and these components could be accounted for 73% of PM2.5 mass. Reactive forms of {{{{ { NH}`_{4 } ^{+ } }}}} were considered as NH4HO3 and NH4{{{{ {SO }`_{4 } ^{2- } }}}} during the sampling periods. {{{{ { NO}`_{3 } ^{- } }}}}/({{{{ { NO}`_{3 } ^{- } }}}} + HNO3) and {{{{ {SO }`_{4 } ^{2- } }}}}/({{{{ {SO }`_{4 } ^{2- } }}}} + SO2) were calculated 0.8 and 0.9 respectively. Most of these compounds might be formed in partiiculate phase in the air. Correlation coefficient between OC and EC was 0.866 which might have the same sources during the sampling periods,.

• 한국대기환경학회지
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• 제27권4호
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• pp.395-404
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• 2011

Asian dust evens took place in Seoul on 27~28 March and 31 March~1 April 2007, during which the mass and chemical compositions of $PM_{10}$ were measured at urban area in Seoul, Korea. In conjunction with $PM_{10}$ compositions, the behaviors of gas precursors such as CO, $O_3$, $SO_2$, and $NO_2$ and meteorological parameters and air mass trajectories were thoroughly examined. The earlier case was a weak dust incidence which was characterized by elevated concentrations of CO, $SO_2$ and $NO_2$ as well as secondary aerosols. In contrast, the later showed the trait of the dust aerosols associated with high $PM_{10}$ mass and $Ca^{2+}$ concentrations. In general, the fractions of ionic species against mass decreased with increase in dust loading. The ratios of ${SO_4}^{2-}$ to ${NO_3}^-$ and $SO_2$ to $NO_2$ were similar in temporal variations, suggesting the concentrations of secondary aerosols were sensitive to the level of precursor gases. In this study, $Na^+$ and $Cl^-$ were also highly elevated during the heavy dust episode, which is thought to have originated from alkaline soils spreading through the northeast regions of China.

• 대한화학회지
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• 제46권6호
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• pp.523-527
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• 2002

LPG에서 황화합물의 분배계수에 미치는 영향에 관하여 연구하였다. 분석 대상 물질은 알칸계통에 사슬형머캡탄이었다. LPG의 액체상 및 기체상의 조성을 기체크로마토그래피로 분석하였다. SAS를 사용한 다중회귀분석방법(MLR)으로 황화합물의 끓는점(Bp), 온도(Tk), 용매의 조성(C4)과 관련되 분배계수를 다음과 같이 구할 수 있었다. Kpc=0.61222(${\pm}$0.000959)Bp+0.26984(${\pm}$0.06504)C40.003803(${\pm}$0.0019993)Tk, N=24, F=14.851, $R^2_{adj}$=0.6437. 분배계수에 미치는 중요 인자는 황화합물의 대기압에서 끓는점과 LPG의 조성이었다. n-부탄의 높은 조성 및 높은 온도에는 분배계수가 증가하여 가스의 취기 상승효과가 클 것으로 추측된다.