• 한국토양비료학회지
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• 제40권4호
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• pp.326-329
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• 2007

Quantifying soil organic carbon (SOC) has long been considered to improve our understanding of soil productivity, soil carbon dynamics, and soil quality. And also SOC could contribute as a major soil management factor for prescribing fertilizers and controlling of soil erosion and runoff. Reducing tillage intensity has been recommended to sequester SOC into soil. On the other hand, determination of traditional SOC could barely identify the tillage practices effect. Physical soil fractionation has been reported to improve interpretation of soil tillage practices impact on SOC dynamics. However, most of these researches were focused onupland soils and few researches were conducted on paddy soils. Therefore, the objective of this research was to evaluate paddy soil tillage impact on SOC by physical soil fractionation. Soils were sampled in conventional-tillage (CT), partial-tillage (PT), no-tillage (NT), and shallow-tillage (ST)plots at the National Institute of Crop Science research farm. Samples were obtained at the three sampling depth with 7.5-cm increment from the surface and were sieved with 0.25- and 0.053-mm screen. Soil organic carbon was determined by wet combustion method. Significant difference of SOC contentwas found among sampling soil depth and soil particle size. SOC content tended to increase at the ST plot with increasing size of soil particle fraction. We conclude that quantifying soil organic carbon by physical soil particle fractionation could improve understanding of SOC dynamics by soil tillage practices.

• Elastomers and Composites
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• 제55권2호
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• pp.108-113
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• 2020

Wear particles of the model tread compounds for bus and truck tires were made using a laboratory abrasion tester and characterized based on their size distributions, shapes, and crosslink densities. The influence of the carbon black contents and rubber compositions (NR= 100 and NR/BR= 80/20) on the production of wear particles was investigated. The wear particles were separated according to size using a sieve shaker. The shape properties of the wear particles were analyzed using an image analyzer and scanning electron microscopy (SEM). Their shapes were observed as tiny stick cookies or sausages with bumpy surfaces. The particle size distribution tended to be smaller with increasing carbon black content. Moreover, the particle size distributions of the NR = 100 samples were larger than that of the NR/BR blend samples. There were different filaments in the wear particles. The filament diameters tended to be thinner with increasing carbon black content. The crosslink density increased with increasing carbon black content, and the crosslink densities of the NR= 100 samples were lower than those of the NR/BR blend ones. The particle size distribution tended to be smaller with increasing crosslink density. Based on the experimental results, the wear particles can be produced by detaching debris from the main body through repetitive strain and recovery.

• 공업화학
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• 제9권5호
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• pp.781-785
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• 1998

무정형탄소인 petroleum cokes를 대상으로 attrition mill을 이용하여 6~48시간 동안 분쇄한 후 이를 $700^{\circ}C$에서 1시간 동안 열처리한 후 재료특성과 전기화학적 특성을 조사하였다. 분쇄에 의한 효과에 의하여 입도분포와 BET 비표면적의 변화가 발생하였으며 내부의 층간거리도 변화시킬 수 있었다. 이들의 재료특성 변화에 의한 cyclic voltammogram과 충 방전 특성과의 관계를 조사한 결과, 분쇄시간 12~24시간에서 분쇄된 후의 경우가 $6{\sim}8{\mu}m$의 평균입도를 가지며 비교적 큰 층간거리와 표면적을 가질 때 전기화학적 특성이 비교적 우수하였다.

• 한국대기환경학회지
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• 제23권2호
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• pp.203-213
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• 2007

Numerical analysis has been performed to understand flow characteristics in the reactor with bag filters in an integrated adsorption/catalytic process which can treat dioxin and $NO_{x}$ together. Computational fluid dynamics technique was employed with Euler-Lagrangian model to consider flue gas and activated carbon particles simultaneously, so that residence time of flue gas and activated carbon particle 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's 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. Flow patterns of flue gas and activated carbon particles in the reactor were very complicated and they moved along very various paths. Therefore, their residence time in the reactor was also various. The results obtained would be effectively used to estimate the removal efficiency in the reactor once the residence time is combined with the reaction equation.

• 한국대기환경학회지
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• 제31권6호
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• pp.497-507
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• 2015

Real-time and quantitative measurement of the chemical composition in ambient aerosols represents one of the most challenging problems in the field of atmospheric chemistry. In the present study, time resolved application by Aerosol-into-Mist System (AIMS) following by total organic carbon analyzer (TOC) has been developed. The unique aspect of the combination of these two techniques is to provide quantifiable water soluble organic carbon (WSOC) information of particle-phase organic compounds on timescales of minutes. We also demonstrated that the application of the AIMS method is not limited to water-soluble organic carbon but inorganic ion compounds. By correlating the volume concentrations by optical particle sizer (OPS), water soluble organic carbon can be highly related to the secondary organic products. AIMS-TOC method can be potentially applied to probe the formation and evolution mechanism of a variety of SOA behaviors in ambient air.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.174-176
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• 2002

A total of 134 patients with stage 1 of non-small cell lung cancer treated by carbon ion beam of HIMAC NIRS were investigated for control rate and delivered dose. The delivered dose of every patient was converted to biological effective dose (BED) of LQ model using fraction number, dose per fraction and alpha beta ratio which shows the maximum correlation between BED and tumor control. The BED of every patient was classified to establish a BED response curve for control. Assuming fraction numbers, dose response curves were introduced from BED response curve. The total doses to realize several control rates were obtained for the treatment of small fraction number.

• Carbon letters
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• 제3권4호
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• pp.226-232
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• 2002

• 대한기계학회논문집B
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• 제27권4호
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• pp.524-533
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• 2003

DBD(Dielectric Barrier Discharge) plasma in air is well established for the production of large quantities of ozone and is more recently being applied to aftertreatment processes for HAPs(Hazardous Air Pollutants). Aim of this work is to determine design and operating parameters of a hybrid air cleaning system. DBD and ESP(Electrostatic Precipitator) are used as nano particle charger and collector, respectively. Pelletized MnO$_2$ catalyst or activated carbon is used fer ozone decomposition or adsorption material. AC voltage of 7～10 KV(rms) and 60 Hz is used as DBD plasma source. DC - 8 KV is applied to the ESP for particle collection. The overall particle collection efficiency for the hybrid system is over 85 % under 0.64 m/s face velocity. Ozone decomposition efficiency with pelletized MnO$_2$ catalyst or activated carbon packed bed is over 90 % when the face velocity is under 0.4 m/s in dry air.

• 대한기계학회논문집
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• 제12권5호
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• pp.1104-1112
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• 1988

본 연구에서는 고체연소미립자로써 탄소입자와 산화제로써 순수 산소를 사용 하였으며, 매우 높은 대류 열 전달 상태에서 탄소입자 표면의 대류 열저항과 고체 내 부의 전도 열 저항에 의하여 발생하는 탄소입자 내부의 온도구배를 고려하여 탄소입자 와 순수 산소의 혼합물에 있어서 이상 폭발현상을 수치적으로 연구하였다.

• 상하수도학회지
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• 제20권5호
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• pp.719-726
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• 2006

Adsorption isotherms and kinetics for taste and odor (T&O) compounds and natural organic matters (NOMs) were performed to evaluate the impacts of activated carbon particle size on coagulation and adsorption. Adsorption capacities for iodine, T&O compounds, and NOM of all the activated carbons under #325 mesh were more excellent than those of virgin activated carbons. Small activated carbon particles were more rapidly adsorbed low molecular weight T&O compounds in the water, while those were slowly adsorbed high molecular weight NOM. When the activated carbon and alum were added simultaneously, the adsorption capacity for organics was better than alum was added alone.