• Nuclear Engineering and Technology
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• 제43권1호
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• pp.1-6
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• 2011

The behavior of the non-equilibrium grain boundary segregation of boron in low carbon steel was studied through a particle tracking autoradiography. The behavior of the non-equilibrium grain boundary segregation of boron during continuous cooling was compared with the isothermal kinetics of the non-equilibrium grain boundary segregation of boron at the holding temperature using an effective time method. On the basis of the experiments, the cooling rate dependence of the non-equilibrium segregation of boron was explained using the time dependence of the non-equilibrium segregation of boron in low carbon steel. The experimental observations for the cooling rate dependence of the grain boundary segregation of boron are in good agreement with the time dependence of the grain boundary segregation of boron. The mechanisms of the non-equilibrium segregation of boron during cooling in low carbon steel are also discussed.

• 한국대기환경학회지
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• 제28권4호
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• pp.411-422
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• 2012

Ground-based in-situ measurements of aerosol optical properties at Gosan climate observatory have been analyzed to investigate the optical contribution of Asian dust and polluted particles on light absorption in springtime 2011. During the Asian dust episode, the contribution of Asian dust particle to aerosol absorption coefficient estimated about 45% at 370 nm and about 23% at 520 nm. Especially, black carbon in dust plume contributes about 48% to aerosol light absorption at 520 nm since the airmass are transported from the Gobi and inner Mongolia deserts, and this airmass comes across the northeastern coast of China, near the Shandong Peninsula. In pollution case, the contributions of dust particle and black carbon to aerosol absorption coefficient estimated about 41% and 11% at 370 nm, respectively. However, pollution case shows the highest light absorption of 48% for brown carbon at 370 nm, which indicates the significantly high mass concentration of organic carbon ($6.3{\pm}2.2{\mu}g\;m^{-3}$) in pollution plume can contribute to the increase of light absorption at near-UV spectral region.

• 한국세라믹학회지
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• 제53권1호
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• pp.93-98
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• 2016

Cold plasma and heat treatment were selected as technologies to reduce unburned carbon in fly ash to less than 1.0%. Both cold plasma and heat treatment made it possible to eliminate unburned carbon to less than 1.0%. In the case of fly ash, which almost entirely eliminated unburned carbon with an ignition loss of 0.5%, heat treatment caused adhesion among particles and the BET specific surface area rapidly decreased as the mean particle size increased. On the other hand, with cold plasma, unburned carbon elimination caused the BET specific surface area to decrease and, as no adhesion occurred among particles, the mean particle size became small. Also, cold plasma treatment allowed small spherical particles confined within the unburned carbon particles to be released with the elimination of the unburned carbon frame, so that the quantity of fine particles had a tendency to slightly increase.

• 대한기계학회논문집B
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• 제31권5호
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• pp.416-424
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• 2007

In adsorption/catalytic process, numerical analysis has been performed to identify the flow characteristics of flue gas in the cyclone and to estimate the residence time of activated carbon using Computational Fluid Dynamics (CFD) technique. To consider flue gas and activated carbon particles simultaneously, Euler-Lagrangian model was employed so that residence time could be obtained from the numerical analysis directly. The numerical analysis has been performed with different three particle sizes and compared each flow characteristics with particle’ size. Fundamental flow patterns of flue gas and activated carbon particles, pressure distribution, residence time of flue gas, and activated carbon particles and distribution of activated carbon have been obtained from the numerical analysis.

• 한국군사과학기술학회지
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• 제11권3호
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• pp.169-175
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• 2008

A fine carbon fibers dispersion model is implemented to calculate the scattering range and ground level concentration of carbon fibers emitted at certain altitudes of atmospheric boundary layer. This carbon fibers dispersion model was composed by coupling a commonly used atmospheric dispersion model and an atmospheric boundary layer model. The atmospheric boundary layer model, applying the Monin-Obukov Similarity Rule obtained from measurement input data at ground level, was used to create the atmospheric boundary layer structure. In the atmospheric dispersion model, the Lagrangian Particle Model and the Markov Process were applied to calculate the trajectory of scattered carbon fibers relative to gravity and aerodynamic force, as well as carbon fibers specification.

• 한국산업보건학회지
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• 제23권4호
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• pp.323-332
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• 2013

Objectives: This study was conducted in order to investigate the diesel exhaust particle(DEP) concentrations in the thirteen parking lots of large shopping complex. Methods: The real-time black carbon(BC) concentration was determined using an Aethalometer, and elemental/organic carbon concentration was determined according to the method of the National Institute for Occupational Safety and Health(NIOSH) 5040. The particle number concentration(NC), lung deposited surface area concentration(LDSA) and geometric mean diameter(GMD) were determined using a DiSCmini aerosol monitor. Results: The average concentration of BC, EC, OC, NC, LDSA and GMD were $19.1{\mu}g/m^3$, $12.6{\mu}g/m^3$, $51.5{\mu}g/m^3$, $94,000particles/cm^{-3}$, $298{\mu}m^2/cm^{-3}$ and 57 nm in all parking lots, respectively, approximately 3-fold higher than those found in the urban outdoor. The average concentration of BC were $21.3{\mu}g/m^3$ in underground parking lots, 3-fold higher than above parking lots. Conclusions: Therefore, the parking lots at the large shopping complex can be considered a potentially dangerous environment with a high concentration of DEP nanoparticles.

• 상하수도학회지
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• 제25권4호
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• pp.471-478
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• 2011

A series of laboratory experiments carried out to investigate the particle separation efficiency and flotation characteristics using $CO_2$ bubbles. The primary objective of this study was to find out the feasibility of $CO_2$ bubbles as an applicable unit of flotation process in tap-water and wastewater treatment plant. The fundamental measurements were conducted to characterize the $CO_2$ bubble from the physical viewpoint in water including bubble size distribution and rising velocity under various operational conditions. In addition, the removal efficiency of solid was experimented using the lab scale plant applied $CO_2$ bubbles, namely the dissolved carbon dioxide flotation (DCF) process. The DCF process using carbon dioxide bubble, which is an advantage as the decrease and the reuse of Green-House gas, can be a promising technology as an water treatment process. On the other hand, the further research to decrease the bubble size distribution of $CO_2$ is required to enhance the particle separation efficiency.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.628-633
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• 2013

토너 입자 내부의 카본블랙의 분산성이 우수한 스타이렌 기반 현탁중합토너를 제조하기 위하여 카본블랙의 표면을 개질하였다. 산화반응을 통해 카본블랙 표면에 도입된 히드록시기와 유기산(올레산, 팔미트산, 아크릴산)의 카르복시기 사이의 에스터화 반응을 통해 표면이 유기화 개질된 카본블랙을 제조하였다. 카본블랙의 표면개질을 확인하기 위하여 FTIR을 이용하였다. 바인더 수지 모노머 혼합물에 대한 카본블랙의 가시적인 분산성 실험을 진행하였으며 입도분석기를 이용해 분산된 카본블랙의 입자 크기를 측정하였다. 광학현미경 사진을 분석한 결과 표면이 올레산으로 개질된 카본블랙을 사용할 경우 토너 입자 내부의 카본블랙의 분산성이 크게 향상되었다. 올레산으로 개질된 카본블랙을 이용해 제조한 중합토너는 입경 및 입경분포도 토너로서 이상적이었다.

• 한국대기환경학회지
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• 제21권3호
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• pp.367-375
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• 2005

Low-Z particle Electron Probe X-ray Microanalysis was applied to characterize MSW fly- and bottom -ash particle samples originated from two municipal incinerators (denoted as A and B) in Korea. According to their chemical composition, many distinctive particle types were identified. In A fly ash, the major chemical species are carbon-rich, aluminosilicates and many particles are composed of as a mixture of $ CaCO_3$ and other chemical species such as $CaSO_4$ or $CaCl_2$. For B fly ash, Fe, iron oxide, NaCl and NaCl-containing particles are the most abundant. In bottom ash, A and B were composed of similar chemical species such as carbon-rich, Fe, iron oxide, $CaCO_3$, and aluminosilicates. It was demonstrated that the single-particle characterization using this low-Z particle EPMA technique provided detailed information on various types of chemical species in the MSW ash samples. In addition, the technique has advantage over conventional analytical techniques in the point that both crystalline and glass-like ash particles can be analyzed at the same time.

• 전기학회논문지
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• 제63권2호
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• pp.319-324
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• 2014

The wafer carrier is made of PP, PC, PE resin which have excellent heat and chemical resistance and electrical properties. However, particle generation has become a problem due to static electricity generated in the carrier. Some conductive material such as carbon black (CB) and carbon fiber (CF) are added for the purpose of anti-static, however, additional for motility and particle contamination problems due to high carbon content occurs. In this paper, the electrical characteristics and workability are observed and compared by adding low Carbon Nono Tube(CNT) to each PP, PC and PE resin to solve the problem.