• 한국대기환경학회지
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• 제32권1호
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• pp.1-8
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• 2016

Optical particle sizer (OPS), optical particle counter (OPC), and aethalomter were deployed to measure the particle number concentrations from 0.3 to $10.0{\mu}m$ and black carbon (BC) concentrations. Comparisons of particle number concentrations measured by OPS and OPC were conducted to evaluate the performance of the each optical instrument at the Gwangju sampling site ($35.23^{\circ}N$, $126.84^{\circ}E$) for 14 days from Dec. 27 in 2014. Although a good correlation ($r^2=0.99$) between the OPS and OPC was observed for both the particle number and volume concentrations, different relationships by BC concentrations can be associated with the intensities by different light scattering angles. In addition, based on diurnal patterns of size distributions in 24 hr running correlation coefficient determination, BC concentrations were highly related to the particles less than $0.3{\mu}m$ observed in the morning traffic hour.

• Korean Chemical Engineering Research
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• 제47권6호
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• pp.747-754
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• 2009

본 연구에서는 $1,000^{\circ}C$에서 24시간 열처리된 활성탄에서 다이옥신과 유사구조를 갖는 o-DCB(ortho-dichlorobenzene)의 등온흡착식을 실험을 통하여 구하였고, 분자모사를 통하여 예측하였다. 실험으로 분석된 활성탄의 분자식 및 작용기 비율을 바탕으로 초기 활성탄 기본구조를 설계한 후, COMPASS(condensed-phase optimized molecular potentials for atomistic simulation studies) force field를 이용하여 이 구조를 최적화하였다. 최적화된 활성탄 분자구조에서 공극률, 비표면적, 및 입자밀도의 모사결과는 실험값과 비교되었고, 이들에 대한 실험과 모사결과의 오차는 각각 7.62, 3.79, 2.80%를 보여주었다. 통계 열역학적 방법인 GCMC(Grand Canonical Monte Carlo) 기법을 이용하여, 최적화된 활성탄 구조에서 온도에 따른 o-DCB의 등온흡착 상수값을 예측하였으며, 이 모사결과는 실험값과 비교될 때, 3% 이하의 오차를 보였다. o-DCB의 흡착특성을 바탕으로 확인되어진 활성탄 구조에서 다이옥신의 일종인 2,3,7,8-TCDD(tetrachlorodibenzo-p-dioxin) 등온흡착상수, 흡착열, 그리고 기공확산계수를 최종적으로 구함으로서, 실험적으로 구하기 힘든 맹독성 잔류성 유기물질의 흡착특성을 분자모사기법을 통하여 예측하였다.

• 한국대기환경학회지
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• 제21권6호
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• pp.639-647
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• 2005

A single particle analytical technique, named low-Z particle electron probe X-ray microanalysis (EPMA), was applied to characterize samples collected at a subway station and ambient samples in Seoul. According to their chemical composition, many distinctive particle types were identified. For samples collected at the subway station platform, the major chemical species are carbon-rich, organic, aluminosilicates (AlSi), AlSi/C, AlSi/$CaCO_{3},\;CaCO_{3},\;SiO_{2},\;and\;Fe_{2}O_{3}$. For outdoor samples, carbon-rich, organic, AlSi, $CaCO_{3},\;SiO_{2},\;NaNO_{3},\;(Na,Mg)NO_{3},\;Na(CO_{3},NO_{3},SO_{4}),\;and\;(NH_{4})_2SO_4$, are abundantly encountered. Samples collected at the subway station show very high contents of $Fe_{2}O_{3}$, both in coarse and fine fractions, which come from brake block, subway train wheel, electric contact materials, etc. It is demonstrated that the single-particle characterization using this low-Z particle EPMA technique provided detailed information on various types of chemical species in indoor and outdoor samples.

• 한국환경과학회지
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• 제31권9호
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• pp.767-779
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• 2022

In this study, sediment cores were sampled from tidal flats (six sites) in the west and south coastal wetlands, the blue carbon stock in the tidal flat sediments was calculated, and the blue carbon stock characteristics and influencing factors were analyzed. The sediment particle size of the west coastal tidal flats was larger than that of the south coastal tidal flats, and the organic carbon content in the south coastal tidal flats was more than twice that of the west coastal tidal flats. Blue carbon stock per unit area was 28.4~36.8 Mg/ha on the west coastal tidal flats and 69.8~89.8 Mg/ha on the south coastal tidal flats, which was more than twice higher in the south coastal tidal flats than in the west coastal tidal flats. The total amount of blue carbon stock in the tidal flats was the highest in Suncheon Bay tidal flats at 153,626 Mg, and followed by Gomso Bay tidal flats at 141,750 Mg, Hampyeong Bay tidal flats at 58,420 Mg, Dongdae Bay tidal flats at 44,900 Mg, Cheonsu Bay tidal flats at 36,880 Mg, and Jinhae Bay tidal flats at 26,205 Mg. Blue carbon stock per unit area was higher in the south coastal tidal flats, but the total amount of blue carbon stock in the tidal flats was higher in the west coast. The slope of the regression function of blue carbon stock with respect to the organic carbon content in the tidal flat sediments was estimated to be about 0.05 to 0.07, and the slope of the regression function was higher in the west coastal tidal flats than in the south coastal tidal flats.

• 한국대기환경학회지
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• 제20권6호
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• pp.823-832
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• 2004

Atmospheric aerosol particles collected in Seoul on four single days, each in every seasons of 2001, were characterized and classified on the basis of their chemical species using low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA). Low-Z particle EPMA technique can analyze both the size and the chemical species of individual aerosol particles of micrometer size and provide detailed information on the size distribution of each chemical species. The major chemical species observed in Seoul aerosol were aluminosilicate, silicon dioxide, calcium carbonate, organic, carbon-rich, marine originated, and ammonium sulfate particles, etc. The soil originated species, such as aluminosilicate, silicon dioxide, and calcium carbonate were the most popular in the coarse fraction, meanwhile, carbonaceous and ammonium sulfate were the dominant species found in the fine fraction. Marine originated species such as sodium nitrate was frequently encountered, up to 30% of the analyzed aerosol particles.

• 공업화학
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• 제3권4호
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• pp.701-709
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• 1992

콜로이드 방법에 의해 은입자를 카본블랙에 담지시켜 알칼리형 연료전지의 산소극의 촉매로 사용하였다. $AgNO_3$와 $NaBH_4$의 혼합용액에 sodium dodecyl benzenesulfonate를 첨가하여 콜로이드 용액을 만들었고 이를 전기영동법으로 확인하였다. 입자크기에 대한 전극성능의 영향과 화학흡착을 고찰한 결과 $200{\AA}$의 촉매로 제조한 전극이 가장 우수하였으므로 이를 위해 계면활성제의 첨가효과, 담지시의 교반시간과 담체로 사용되는 카본의 분산성에 따른 은입자의 응집현상을 검토하였다. 열처리 효과에 의한 입자 크기의 증가를 고려할 때 계면활성제의 첨가량을 $10mg/{\ell}$으로 하고 9시간 교반하여 $100{\AA}$의 입자크기를 갖는 촉매를 제조한 뒤 이를 이용하여 전극을 제작하는 것이 가장 좋았다. 또한 카본블랙을 초음파 분산기로 분산시키는 경우 30초 이후에는 재응집현상이 일어남을 알 수 있었다.

• 한국자기공명학회논문지
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• 제6권1호
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• pp.38-44
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• 2002

60% Pt on Vulcan XC-72 with similar Pt sizes to fuel cell grade Pt black was investigated by $\^$13/C nuclear magnetic resonance spectroscopy (NMR), cyclic voltammery (CV), transmission electron microscopy (TEM). Experiments were carried out on electrochemically cleaned samples as well as as-received. The TEM and CV results showed that the average particle sizes were changed by cleaning. However, the chemical shift （$\delta$$\_$G/） of $\^$13/C of $\^$13/CO absorbed on Pt surfaces did not show any appreciable variation with particle size change as did in Pt black. These results indicate that a combination of different analytic techniques is essential to understand the properties of the metal particle catalysts and that the presence of carbon black support strongly influences the NMR data, probably through metal-support interaction.

• 동력기계공학회지
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• 제10권1호
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• pp.46-51
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• 2006

Present study was investigated the effect of the particle of the counterface of unidirectional carbon fiber reinforced composite. The friction coefficient of composite and the specific wear rate different sliding velocity were measured for this materials. The friction track of counterface was observed by an optical microscope and scanning electron microscope. There were insignificant effects of the specific wear rate under lower Sic abrasive particle, however it showed high effect on $30{\mu}m$ abrasive particle size. There were significant effects of friction and wear behavior of the fiber direction under 0.3m/s sliding speed. Major failure mechanisms can be classified such as microfracture, plowing, microcutting, cutting and cracking.

• 한국환경과학회지
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• 제30권3호
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• pp.279-287
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• 2021

In this study, the composition and morphology of deposited dust particles with size ranging from a few to tens ㎛ were investigated using SEM/EDX (scanning electron microscopy with energy dispersive x-ray spectrometer). Then deposited dust particles were classified into 8 groups: quartz, aluminosilicates, ca-rich, Fe/Ti oxide, carbon-rich, industrial particle, Fe-rich, and biogenic particle. The sources of deposited dust were high in the order of aluminosilicates 41% > biogenic 18% > Fe-rich 11% > quartz and C-rich 8% > industrial 7% > Fe/Ti oxide 5% > Ca-rich 1%. In particular, the ratio of biogenic particles was relatively high due to influence of pollen. The ratio of carbon-rich was 11% at YM site, 10% at MD site, and 4% at MO site, and the site close to the large emission source was high.

• Medical Lasers
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• 제10권4호
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• pp.242-245
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• 2021

Acne vulgaris is a common inflammatory skin disease of the pilose-baceous unit. It appears as lesions consisting of comedones, papules, pustules, and nodules of varying shapes and severity. In general, the first-line treatment for acne vulgaris includes topical and oral medication. Recently, various physical modalities have also been investigated. The use of laser therapy is steadily increasing because of its fewer side effects, short procedure time, and rapid results. In particular, laser therapy assisted with carbon suspension application is effective for acne vulgaris but may sometimes result in discomfort due to odor and dust formation during the procedure. Herein, we report that acne vulgaris and enlarged facial pores can be safely and effectively treated with laser therapy assisted with diamond particle suspension and gold microparticle application, which can address the discomfort caused by the carbon suspension application.