• Journal of Korean Society for Atmospheric Environment
• /
• v.13 no.3
• /
• pp.179-191
• /
• 1997

The concentrations of organic and elemental carbon were determined using fine particle samples collected from Kosan, Cheju Island during the summer seasons of 1994 and 1995. The daily mean concentrations of organic and elemental carbon for each measurement period were 3.74 and 0.27 $\mu\textrm{g}$/㎥ in 1994, while those of 1995 were 2.36 and 0.10 $\mu\textrm{g}$/㎥, respectively The concentrations of organic carbon were higher than those commonly observed from clean areas around the world, but those of elemental carbon were lower than, or comparable to, other clean areas in the world. The resulting ratios of total carbon to elemental carbon at this site were thus higher than those seen from other metropolitan and non-polluted regions abroad. In addition according to our analysis, the 1994 measurement period can be classified into two periods: enhanced (July 20 and August 1) and reduced levels (August 2 and 9) of the carbonaceous species. The observed difference between two periods may be in part accounted for by the air trajectories representing each period. During the former period, the air masses from the Asian continent and Japan were dominant, while the air masses from the North Pacific Ocean came during the latter period. OC/EC ratios at the site were calculated to predict the possible formation of secondary organic aerosol . Based on our observations, we suggest that the formation of secondary organic aerosol might be an important pathway to the production of organic carbons.

• Carbon letters
• /
• v.11 no.3
• /
• pp.184-191
• /
• 2010

Carbon nanotubes are unique tubular structures of nanometer diameter and large length/diameter ratio. The nanotubes may consist of one up to tens and hundreds of concentric shells of carbons with adjacent shells separation of ~0.34 nm. Multiwalled carbon nanotubes were synthesized by arc-discharge technique. MWCNTs were formed at the cathode deposit along with other carbonaceous materials like amorphous carbon, graphite etc. However, to get the best advantage of carbon nanotubes in various advanced applications, these undesired carbonaceous materials to be removed which is a challenging task. In the present study, various techniques were tried out for purifying MWCNTs such as physical filtration, chemical treatment and thermal annealing. SEM, FTIR, TGA and BET techniques were used to characterize the CNTs at various stages. Results shows that suitable chemical treatment followed by thermal annealing under controlled flow of oxygen gives the better route for purification of carbon nanotubes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1220-1223
• /
• 2003

A new type electric double layer capacitor (EDLC) was constructed by using carbon nanofibers (CNFs) and DAAQ(1,5-diaminoanthraquinone) electrode. Carbonaceous materials are found in variety forms such as graphite, diamond, carbon fibers etc. While all the carbon nanofibers include impurities such as amorphous carbon, nanoparticles, catalytic metals and incompletely grown carbons. We have eliminated of Ni particles and some carbonaceous particles in nitric acid. Nitric acid treated CNFs could be covered with very thin DAAQ oligomer from the results of CV and TG analyses and SEM images. A crystalline supramolecular oligomer of 1,5-diaminoanthraquinone(DAAQ) was successfully prepared as a thin film by electrochemical oxidation from an acidic non-aqueous medium. DAAQ oligomer film exhibited a specific capacity as 45-50 Ah/kg in 4M $H_2SO_4$. Its electrochemical characteristics were investigated by cyclic voltammetry. And compared with different electrolyte of aqueous type. During ultrasonic irradiation CNFs was to disperse in 0.1M $H_2SO_4$. As a result, CNFs coated by DAAQ composite electrode showed relatively good electrochemical behaviors.

• Journal of Environmental Science International
• /
• v.17 no.8
• /
• pp.833-840
• /
• 2008

Deoxygenation process in which CBOD(carbonaceous BOD) is biochemically oxidized to reduced inorganic compounds is of great significance in the oxygen demand of stream waters. The CBOD decay rate has traditionally been determined in a laboratory by CBOD bottle incubation method. But in this study, CBOD decay rates were obtained by laboratory incubation method and natural waters experiment. Average CBOD decay rate for the Nakdong river(upper zone) in natural waters were 0.553 $day^{-1}$ during April 2005 to January 2007. The values in the middle and down parts of the Nakdong river in natural waters were 0.384 $day^{-1}$ and 0.252 $day^{-1}$ at the same period of time, respectively. Average CBOD decay rates using by incubation method in the upper/middle/down parts of the main stream in the Nakdong river basin was 0.270 $day^{-1}$, and 0.289 $day^{-1}$, and 0.283 $day^{-1}$ during April 2005 to January 2007, respectively.

• Journal of Korean Society for Atmospheric Environment
• /
• v.30 no.5
• /
• pp.461-476
• /
• 2014

Continuous Water-Soluble Organic Carbons (WSOC) by the Particle Into Liquid Sampler - Total Organic Carbon (PILS-TOC) analyzer were measured at the Seoul intensive monitoring site from June 17 through July 5 in 2014. In addition, the 24 hour integrated PM2.5 collected by Teflon and Quartz filters were analyzed for water soluble ions by Ion chromatography (IC), WSOC by TOC from water extracts, organic carbon (OC), elemental carbon (EC) by carbon analyzer using the thermal optical transmittance (TOT) method, and mass fragment ions (m/z) related to alkanes and PAHs (Poly Aromatic Hydrocarbons) by Gas Chromatography-Mass Spectrometer-Thermal Desorption (GC/MS-TD). Based on the statistical analysis, four different Carbonaceous Thermal Distributions (CTDs) from OCEC thermal-gram were identified. This study discusses the primary and secondary sources of WSOC based on the Classified CTD, organic mass fragments, and diurnal patterns of WSOC. The results provide knowledge regarding the origins of WSOC and their behaviors.

• Applied Chemistry for Engineering
• /
• v.18 no.1
• /
• pp.1-9
• /
• 2007

Compressed natural gas (CNG) has been used as a vehicular fuel compressed at 24.8 MPa because the energy density of natural gas is extremely low compared with gasoline. Thus it has problems in both safety and cost for multiple stage compression. For these reasons the use of adsorbed natural gas (ANG) has been pursued since the storage of natural gas is possible at a relatively low pressure. The present target is to obtain media to store natural gas at 3.5 MPa as ANG that ensures the comparable energy density of CNG, giving approximately one-fourth the driving range of an equivalent volume gasoline tank. In this review, the recent development of carbon media, their characteristics, and practical applications for natural gas storage are introduced and some recommendations are also suggested.

• Journal of Electrochemical Science and Technology
• /
• v.1 no.1
• /
• pp.25-30
• /
• 2010

This study demonstrated the synthesis of high-surface-area metal-free carbonaceous electrodes (CE) from anodic aluminum oxide (AAO) templates, and their application as supercapacitors. Multi-walled Carbon nanotubes (MWCNTs) were interwoven into a porous network sheet that was attached to one side of AAO template through a vacuum filtration of the homogeneously dispersed MWCNT toluene solution. Subsequently, the conducting polymer was electrochemically grown into the porous MWCNT network and nanochannels of AAO, leading to the formation of a carbonaceous metal-free film electrode with a high surface area in the given geometrical surface area. Typical conducting polymers such as polypyrrole (PPY) and poly(3,4-ethylenedioxythiophene) (PEDOT) were examined as model systems, and the resulting electrodes were investigated as supercapacitors (SCs). These SCs exhibited stable, high capacitances, with values as high as 554 F/g, 1.08 F/$cm^2$ for PPY and 237 F/g, 0.98 F/$cm^2$ for PEDOT, that were normalized by both the mass and geometric area.

• Journal of Korean Society on Water Environment
• /
• v.23 no.2
• /
• pp.188-192
• /
• 2007

The biochemical oxygen demand (BOD) test is widely used to determine the pollution strength of water, to evaluate the performance of wastewater treatment plants and to judge compliance with discharge permits. However, nitrification is a cause of significant errors in measuring BOD, particularly when a large population of nitrifying organisms is existing in water such as effluents from biological treatment plants. In order to investigate the amount of nitrogenous oxygen demand (NOD), BOD with and without inhibitor was measured as samples in the biological treatment plants. About 81% of effluent BOD from the biological treatment plant used in this experiment was comprised of NOD. In the case of influents, the NOD accounted for about 9% of BOD. The inhibited 5-day BOD (Carbonaceous BOD) test must be considered in evaluating the performance of wastewater treatment plant and judging compliance with discharge permit limitations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07b
• /
• pp.1184-1187
• /
• 2003

Electrochemical capacitors are becoming attractive energy storage systems particularly for applications involving high power requirements such as hybrid systems consisting of batteries and electrochemical capacitors for electric vehicle propulsion. A new type electric double layer capacitor (EDLC) was constructed by using carbon nanofibers (CNFs) and DAAQ(1,5-diaminoanthraquinone) electrode. Carbonaceous materials are found in variety forms such as graphite, diamond, carbon fibers etc. While all the carbon nanofibers include impurities such as amorphous carbon, nanoparticles, catalytic metals and incompletely grown carbons. We have eliminated of Ni particles and some carbonaceous particles in nitric acid. Nitric acid treated CNFs could be covered with very thin DAAQ oligomer from the results of CV and TG analyses and SEM images. DAAQ oligomer film exhibited a specific capacity as 45-50 Ah/kg in 4M $H_2SO_4$. We established Process Parameters of the technique for the formation of nano-structured materials. Furthermore, improved the capacitive properties of the nano structured CNFs electrodes using controlled solution chemistry. As a result, CNFs coated by DAAQ composite electrode showed relatively good electrochemical behaviors in acidic electrolyte system with respect to specific capacity and scan rate dependency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.5
• /
• pp.403-406
• /
• 2019

We prepared yarned carbon nanotube (CNT) fibers from a CNT forest synthesized on a Si wafer by chemical vapor deposition (CVD). The yarned CNT fibers were thermally annealed to reduce their resistance by removing the amorphous carbonaceous impurities present in the fibers. The resistance of the yarned CNT fiber gradually decreased with an increase in the annealing temperature from $200^{\circ}C$ to $400^{\circ}C$ but increased again above $450^{\circ}C$. We carried out thermogravimetric analysis (TGA) to confirm the burning properties of the amorphous carbonaceous impurities and the crystalline CNTs present in the fibers. The pattern of the mass change of the sample CNT fibers was very similar to that of the resistance change. We conclude that CNT fibers should be thermally annealed at temperatures below $400^{\circ}C$ for reducing and stabilizing their resistance.