• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1598-1600
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• 2003

Microcrystalline silicon(c-Si:H) thin-film solar cells are prepared with intrinsic Si-layer by hot wire CVD. The operating parameters of solar cells are strongly affected by the filament temperature ($T_f$) during intrinsic layer. Jsc and efficiency abruptly decreases with elevated $T_f$ to $1400^{\circ}C$. This deterioration of solar cell parameters are resulted from increase of crystalline volume fraction and corresponding defect density at high $T_f$ The heater temperature ($T_h$) are also critical parameter that controls device operations. Solar cells prepared at low $T_h$ (<$200^{\circ}C$) shows a similar operating properties with devices prepared at high $T_f$, i.e. low Jsc, Voc and efficiency. The origins for this result, however, are different with that of inferior device performances at high $T_f$. In addition the phase transition of the silicon films occurs at different silane concentration (SC) by varying filament temperature, by which highest efficiency with SC vanes with $T_f$.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.491-498
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• 2009

We studied to develop high-efficiency removal system of odor and VOCs(Volatile Organic Compounds) from environmental infrastructure facilities and oil refineries, painting facilities and so on. It can replace RTO and RCO. We tried an removal experiment for VOCs (toluene, xylene, benzene, MEK(methyl ethyl ketone), ethanol, formalin etc. and odor compounds (hydrogen sulfide, etc.). In process, as pre-treatment we used the scrubber with vortex flow (Multi-scrone) to remove the hydrophilic VOCs and as post-treatment, used fibrous bio-filter to remove the hydrophobic VOCs. This hybrid system remove with high efficiency both the hydrophilic VOCs and hydrophobic VOCs. And we tried to make this system to be compact. In experiment using Multi-scrone, contact time is 2~3 seconds and absorption scrubbing water is diaphragm-type electrolysis water. hydrophilic VOCs like ethanol and relatively hydrophilic odor compounds like hydrogen sulfide is excellent, these substances has been removed almost completely, respectively 95~99%, 93~97%. And for MEK, formalin also Showed a high removal efficiency, respectively 78~90%, 72~85%. But in experiment using Multi-scrone, the hydrophobic VOCs like BTX showed a low removal efficiency, respectively 16~22%, 12~18%, 8~16%. In hydrophobic VOCs, toluene removal experiment using fibrous bio-filter, early efficiency was low but after 10days, adaptation period showed high efficiency 85~95%. but in the mixed phase, toluene and MEK efficiency reduced 5~10%. this show microorganism treat first MEK easy to remove. The removal efficiency for MEK using the fibrous biofilter was stable, 80~92%. This hybrid system is also high economical efficiency for RTO. This system reduce more than 50% the cost of equipment and maintenance. As a result, we expect this technology is in the limelight as high efficiency treatment of VOCs in mid-low price.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.137-141
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• 2010

Poly [4,7-Di-thiophen-2-yl-benzo(1,2,5)thiadiazole]-alt-1,4-bis(dodecyloxy)-2,5-divinylbenzene (PPVTBT) was synthesized by the Heck coupling reaction between 4,7-Di-thiophen-2-yl-benzo(1,2,5)thiadiazole and 1,4-bis(dodecyloxy)-2,5-divinylbenzene. The maximum absorption and band gap of PPVTBT were 550 nm and 1.74 eV, respectively. The HOMO and LUMO energy level of PPVTBT were -5.24 eV and -3.50 eV, respectively. The photovoltaic device based on the blend of PPVTBT and (6)-1-(3-(methoxycarbonyl)propyl)-{5}-1-phenyl[5,6]-$C_{61}$ (PCBM) (1 : 6 by weight ratio) was fabricated. The efficiency of device was 0.16%. The short circuit current density (Jsc), fill factor (FF) and open-circuit voltage (Voc) of the device was $0.74mA/cm^{2}$, 31% and 0.71 V, respectively, under AM 1.5 G and 1 sun condition ($100mA/cm^{2}$).

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.273-278
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• 2009

A series of poly[2-(2,6-dimethylpyran-4-ylidene)malononitrile-alt-1,4-bis(dodecyloxy)-2,5-divinylbenzene] (PM-PPV), poly[2-{2,6-Bis-[2-(5-bromothiophen-2-yl)-vinyl]-pyran-4-ylidene}-malononitrile-alt-1,4-bis(dodecyloxy)-2,5-divinylbenzene] (PMT-PPV) and poly[2-[2,6-Bis-(2-{4-[(4-bromophenyl)-phenylamino]-phenyl}-vinyl)-pyran-4-ylidene]-malononitrile-alt-1,4-bis(dodecyloxy)-2,5-divinylbenzene] (PMTPA-PPV) were synthesized by the Heck coupling reaction. The band gap of PM-PPV, PMT-PPV and PMTPA-PPV were 2.18 eV, 1.90 eV and 2.07 eV, respectively. The LUMO energy levels of PM-PPV, PMT-PPV and PMTPA-PPV were 3.65 eV, 3.54 eV and 3.62 eV, respectively and the HOMO energy levels of those were 5.83 eV, 5.61 eV and 5.52 eV, respectively. The photovoltaic devices based on the polymers was fabricated. The efficiency of the solar cells based on PM-PPV, PMT-PPV and PMTPA-PPV were 0.028%, 0.031% and 0.11%, respectively and the open circuit voltage (Voc) was 0.59 V~0.69 V under AM 1.5 G and 1 sun condition ($100mA/cm^2$).

• Clean Technology
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• v.10 no.2
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• pp.61-72
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• 2004

In this study, aqueous/semi-aqueous cleaning agents which consist of organic solvent, surfactant, cosurfactant, and water were developed by changing formulation parameters such as organic solvent type and contents, surfactant type and contents, and cosurfactant/surfactant(A/S) ratio, etc.. And physical properties and flux removal of the formulated cleaning agents have been evaluated. Also, the performance of oil-water separation from the rinse water contaminated during the cleaning process was evaluated for its recycling. The formulated cleaning agents in this work expected to have good penetration because of their low viscosity and low surface tension values of 30.2~32.5 dyne/cm. The flux removal with the terpene type cleaning agent was higher than that with hydrocarbon type cleaning agent and two commercial products (CPA(commercial product A), CPB(commercial product B)). And the performance of oil-water separation by gravity settling from the rinse water contaminated with formulated cleaning agent and soils was shown to be very good. The cleaning agents developed in this work were applied to surface mounting technology(SMT) cleaning process for manufacturing electronic parts at L electronic company. As a result, the newly developed cleaning agents showed two times better cleaning speed for removal of solder cream than the conventional ond containing ethanol and IPA(isopropyl alcohol). In addition, malodor and VOC problems generated by the previous organic cleaning agents have been solved in the manufacturing field through introduction of the non-volatile and environmental-friendly cleaning agents to the field.

• Clean Technology
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• v.28 no.4
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• pp.285-292
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• 2022

Adsorption tower systems based on activated carbon adsorption towers have mainly been employed to reduce the emission of volatile organic compounds (VOCs), a major cause of air pollution. However, the activated carbon currently used in these systems has a short lifespan and thus requires frequent replacement. An approach to overcome this shortcoming could be to develop metal oxide photocatalysis-activated carbon composites capable of degrading VOCs by simultaneously utilizing photocatalytic activation and powerful adsorption by activated carbon. TiO₂ has primarily been used as a metal oxide photocatalyst, but it has low economic efficiency due to its high cost. In this study, ZnO particles were synthesized as a photocatalyst due to their relatively low cost. Silver nanoparticles (Ag NPs) were deposited on the ZnO surface to compensate for the photocatalytic deactivation that arises from the wide band gap of ZnO. A microfluidic process was used to synthesize ZnO particles and Ag NPs in separate reactors and the solutions were continuously supplied with a pack bed reactor loaded with activated carbon powder. This microfluidic-assisted pack bed reactor efficiently prepared a Ag-ZnO-activated carbon composite for VOC removal. Analysis confirmed that Ag-ZnO photocatalytic particles were successfully deposited on the surface of the activated carbon. Conducting a toluene gasbag test and adsorption breakpoint test demonstrated that the composite had a more efficient removal performance than pure activated carbon. The process proposed in this study efficiently produces photocatalysis-activated carbon composites and may offer the potential for scalable production of VOC removal composites.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.113-116
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• 2005

In this paper, silicon thin-film solar cells(Si- TFSC) and a-Si/c-Si heterojunction solar cells(HJ-cell) are investigated. The Si-TFSC was prepared on glass substrate by depositing $1-3{\mu}m$ thin-film silicons by glow discharge method. The $a-Si:H/{\mu}c-Si:H$ tandem solar cells on textured ZnO:A1 TCO (transparent conducting oxide) showed improved Jsc in top and bottom cells than that on $SnO_2:F$ TCO. This enhancement of jsc resulted from improved light trapping effect by front textured ZnO:A1. The a-Si/c-Si HJ-cells with simple structure without high efficiency features are suffering from low Voc and Jsc. The improvement of front nip and back interface properties by adopting high quality silicon-films at low temperature should be done both for increasing device performances and production cost.

• Economic and Environmental Geology
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• v.38 no.1
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• pp.57-65
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• 2005

To investigate the characteristics of the volatile organic compounds (VOCs) concentration in the groundwater around Ulsan, Korea, 168 groundwaters, 12 stream waters, and 6 sewage waters were analyzed for 61 VOCs. Results showed that VOCs were not detected in stream waters and total VOCs concentration in 5 sewage waters was in the range of ND-22.3 ${\mu}$g/L. In 78 groundwater samples more than one VOCs were detected and VOCs concentration of the samples ranged from 0.1 ${\mu}$g/L to 387.1 ${\mu}$g/L. However, VOCs concentration of 66 samples out of 78 samples showed less than 10 ${\mu}$g/L and that of only 6 samples exceeded Korea drinking water limit (KDWL). 42 VOCs detected from the 168 groundwaters were 14 aromatic hydrocarbons out of 25, 27 chlorinated aliphatic hydrocarbons out of 35, and methyl tert-butyl ether (MTBE). Detection rate of each VOCs in the groundwaters was as follows: chloroform in 43 samples (25.6%), methylene chloride in 36 samples (21.4%), TCE in 26 samples (15.5%), 1,1-dichloroethane in 19 samples (1.3%), PCE in 16 samples (9.5%), cis-1,2-DCE in 15 samples (8.9%), and toluene in 14 samples (8.3%). Even though VOCs concentration in the groundwaters of the study area is still low, the city is expanding and the drinking water limit is becoming strict, and therefore continuous monitoring is necessary.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.69.2-69.2
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• 2010

Recently, bulk hetero-junction cells have been extensively studied by many researchers. Most of these cells were fabricated by spin coater. However, the spin coating process is not favorable to the large-scaled industry because it is not compatible with roll-to-roll process. One of the alternative methods is Doctor blading. In this study, we fabricated large OPV cells having total area of $100cm^2$. The buffer layer was Poly-(3,4-ethylenedioxythiophene) : poly-(styrenesulfonate) aqueous dispersion (PEDOT:PSS) and the active material is poly (3-hexythiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blend in the solvent of Chlorobenzene. All of the organic layers were coated by dragging the blade with a speed of 5~20 mm/s on the stage with a temperature of $50^{\circ}C$. As-bladed PEDOT:PSS layer was baked at $120^{\circ}C$ for 10 minutes to eliminate the water. The cell structure is patterned ITO substrate/PEDOT:PSS/P3HT:PCBM/LiF/Al. The topmost electrode, LiF/Al, was deposited by thermal evaporation. After depositing electrode, and the cell was annealed at $150^{\circ}C$ for 30 minutes. The measured ISC, VOC, fill factor, and PCE were 2.95 A, 5.86 V, 0.32, and 0.78%, respectively. PCE was quite low but the large active area could be obtained successfully.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.1
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• pp.40-49
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• 2003

This study has been conducted to identify and quantify the emissions of Volatile Organic Compounds (VOCs) from a new carpet. The carpet sample consists of polypropylene cushion and latex backing. The VOCs have been sampled on sorbent tubes and analyzed by thermal desorption unit and GC/MSD. For over 240 hours, concentration of VOCs has been measured in a small chamber made of stainless steel. With the measured data, emission factor and mass balance have been considered. The experiments have been conducted in accordance with ASTM D5116-97. The carpet has emitted a variety of VOCs, but in this study, 7 VOCs compounds have been considered： chlorobenzene, ethylbenzene, styrene, isopropylbenzene, bromobenzene, 2-chlorotoluene, and 1,2,3-trimethylbenzene. The results show that the concentrations of VOCs and the emission factors have exponentially decayed from relatively high level to low level with time. The gradients of the concentration of VOCs and emission factors are different for various components. It is found that styrene, 2-chlorotoluene are emitted more than others with higher concentrations.