• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.183-190
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• 1994

To assess the effects of plant stress by light, temperature, NaCl and soil moisture on photosynthetic activity, the fluorescence method was used for Chinese cabbage(Brassica perkinensis Rupr.), strawberry(Fragaria grandiflora Ehrh.) and citrus tree(Citrus unshiu Marc.). With decreasing the light intensity, Fv/Fm ratios of intact leaves of Chinese cabbage and strawberry increased significantly, indicating lower photochemical efficiency in PS II system, resulting in an inverse relationship with the photosynthetic activity. Chinese cabbage and strawberry that were grown at higher temperature had higher Fv/Fm ratios and photosynthetic activities, while those given high concentration of NaCl and having low soil moisture had lower values. Chinese cabbage more resistant to salt stress and requiring more water had a greater Fv/Fm ratio than strawberry. In citrus tree, Fv/Fm ratio was lower in the non-irrigated group than the irrigated one. From these results, the fluorescence method was found to be a useful tool which can be used to assess the degree of in vivo stress induced by various environmental factors.

• Polymer(Korea)
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• v.38 no.2
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• pp.193-198
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• 2014

Lens and DVD require high quality of optical property. Conventional injection molded products contain high residual stress and this invokes birefringence since high cavity pressure and high temperature variation are involved in a molding process. Thus these products are often molded by injection compression molding in order to minimize the residual stress through reducing cavity pressure and uniform cavity pressure. In this study, molding parameters affecting molding quality such as property uniformity in injection compression molding were investigated through experiment. Molding quality deviations among the cavities in multi-cavity mold were also studied. Transparent resins, PC and PS were used in this study. Compression gap, compression speed, compression force, and compression delay time for processing variables in injection compression molding were applied in experiment. Compression force, compression delay time, and compression gap significantly affected the optical property of product. The degree of influence of process variable on the product quality was different in different resins. This implies that the optimal operational conditions in injection compression molding existed for each resin according to flow property.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.588-596
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• 2006

The surface of polystyrene membrane treated by Ar, $O_2$ plasma, and the effects were observed before and after the treatment and permeability of $CO_2$, $N_2$ and selectivity of $CO_2$ relative to $N_2$ was measured using continuous flow gas permeation analyzer (GPA). The mole ratio of O over C in the surface was increased from 0 to 0.179 with Ar plasma treatment and route mean square of surface was increased from $15.86{\AA}$ to $71.64{\AA}$. Therefore the contact angle was decreased from $89.16^{\circ}$ to $18.1^{\circ}$. Thus Plasma treatments made surface of membrane tend to be highly hydrophilic. The optimum condition for the $CO_2$ permeability and ideal selectivity of the plasma treated membrane was as follows: the measurement of Ar (60 W, 2 min, $70^{\circ}C$) plasma treatment was $1.14{\times}10^{-12}[m^3(STP){\cdot}m/m^2{\cdot}sec{\cdot}atm]$ and 4.22. In the case of $O_2$ plasma treatment, the contact angle was decreased at $13.56^{\circ}$ with increase of O/C ratio ($0.189{\AA}$) and route mean square of surface ($57.10{\AA}$). The optimum condition for the $CO_2$ permeability and ideal selectivity of the plasma treated membrane was as follows: the measurement of $O_2$ (90 W, 2 min, $70^{\circ}C$) plasma treatment was $7.1{\times}10^{-12}[m^3(STP){\cdot}m/m^2{\cdot}sec{\cdot}atm]$ and 11.5. After plasma treatment, the changes of membrane surface were all subtly linked with both cross-linking and etching effects. Finally, it was confirmed that the gas permeation capacity and selectivity of the modified membrane with plasma could be improved by an appropriate control of the plasma conditions such as treatment time, the power input and sort of plasma gas.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1249-1255
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• 2011

In modern large-scale semiconductor manufacturing clean rooms, the energy consumed by the outdoor air-conditioning system during heating, humidification, cooling, and dehumidification of the incoming outdoor air represents about 45% of the total air-conditioning load required to maintain a clean-room environment. In particular, the energy required for humidification of the outdoor air in winter is very high. Therefore, evaluation and comparison of the energy consumption in key humidification systems, viz., steam-humidification and water-spray-humidification systems, used in outdoor air-conditioning systems would be useful to reduce the outdoor air-conditioning load in clean rooms. In the present study, an experiment with an outdoor air flow of 1000 $m^3$/h was conducted to compare the air-conditioning process and energy consumption in outdoor air-conditioning systems with electrodeboiler steam humidifiers and air-washer water spray humidification systems. The experimental results showed that the water-spray-humidification-type outdoor air-conditioning system consumed less electrical power than did the steam-humidification-type system and was more energy efficient during winter.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.243-252
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• 2019

Recently, as the utilization of underground space increases, the demand for underground excavation increases. In this study, the concrete mixture with a new material was used to develop and evaluate the stability of the CS-H wall that can greatly minimize the problems of existing wall and minimize the impact of ground depression and surrounding ground that may occur in the future for excavation of over 30 m deep in urban areas. The fiber reinforcement formulation of steel fibers, synthetic fibers, and glass fibers, along with fine aggregate parts of PS-ball and ferronickel, were mixed. The Mixture ratios were determined by conducting slump test compresive strength test, modulus of elastic test, flexural strength test, splitting tensile strength test and conductivity test. As a result of the test, the steel fiber mixture showed very good results compared to other reference values in all items, and it is considered to be the most suitable for the CS-H wall to be developed.

• Reproductive and Developmental Biology
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• v.35 no.1
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• pp.1-8
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• 2011

Techniques to evaluate gene expression profiling, such as sufficiently sensitive cDNA microarrays or real-time quantitative PCR, are efficient methods for monitoring human pluripotent stem cell (hESC/iPSC) cultures. However, most of these high-throughput tests have a limited use due to high cost, extended turn-around time, and the involvement of highly specialized technical expertise. Hence, there is an urgency of rapid, cost-effective, robust, yet sensitive method development for routine screening of hESCs/hiPSCs. A critical requirement in hESC/hiPSC cultures is to maintain a uniform undifferentiated state and to determine their differentiation capacity by showing the expression of gene markers representing all three germ layers, including ectoderm, mesoderm, and endoderm. To quantify the modulation of gene expression in hESCs/hiPSC during their propagation, expansion, and differentiation via embryoid body (EB) formation, we developed a simple, rapid, inexpensive, and definitive multimarker, semiquantitative multiplex RT-PCR platform technology. Among the 9 gene primers tested, 5 were pluripotent markers comprising set 1, and 3 lineage-specific markers were combined as set 2, respectively. We found that these 2 sets were not only effective in determining the relative differentiation in hESCs/hiPSCs, but were easily reproducible. In this study, we used the hES/hiPS cell lines to standardize the technique. This multiplex RT-PCR assay is flexible and, by selecting appropriate reporter genes, can be designed for characterization of different hESC/hiPSC lines during routine maintenance and directed differentiation.

• Journal of the Korean Graphic Arts Communication Society
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• v.29 no.2
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• pp.59-70
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• 2011

Even though we could not count the total amount of plates in Korean printing industry per year, we would suppose the total amount of plates about $20,000km^2$ to $22,000km^2$ per year through our printing experience. On the standard of the end of 2010, it would be the market share of plates are that CTP plate is $9,000km^2$, CTcP plate is$4,000km^2$ and PS plate is $9,000km^2$, such as total amount of plates are $22,000km^2$. When there was no installed CTP setter in Korea, the domestic plate would be over 60% market share of plate in Korean printing industry. But now it would be less than 25% market share of plate. It is necessary to develop domestic CTP thermal plate from now because we have to keep the market share of domestic plate. On the study of the surface structure of substrate, roughness, anodized layer amount and coating amount between domestic CTP thermal plate and foreign CTP thermal plate, it would be the basic to develop domestic CTP thermal plate.

• Elastomers and Composites
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• v.46 no.4
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• pp.290-294
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• 2011

The surface resistance of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT/PSS), which has appeared to be one of the most successful conductive polymers, is affected by the solvent. In this paper, pellet-type PEDOT/PSS was suspended in $H_2O$, ethanol (EtOH), ethylene glycol (EG) or dimethylsulfoxide (DMSO), and coated on PET film. The surface resistances of the films made from EG or DMSO suspension were observed to be lower, nearly by 2 orders of magnitude, than that made from $H_2O$ suspension. No significant difference among four kinds of films was observed when the thermal properties and chemical structures were investigated by TGA and XPS, respectively. However, particle size of PEDOT/PSS was in the range of $1-3{\mu}m$ in EG or DMSO, on the other hand, less than $0.1{\mu}m$ in $H_2O$. It is considered that the particle size of PEDOT/PSS in the suspension plays an important role for the surface resistance.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4397-4402
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• 2011

The NF-${\kappa}B$ system of transcription factors plays a crucial role in inflammatory diseases, making it an important drug target. We combined quantitative structure activity relationships for predicting the activity of new compounds and quantitative dynamic models for the NF-${\kappa}B$ network with intracellular concentration models. GFA-MLR QSAR analysis was employed to determine the optimal QSAR equation. To validate the predictability of the $IKK{\beta}$ QSAR model for an external set of inhibitors, a set of ordinary differential equations and mass action kinetics were used for modeling the NF-${\kappa}B$ dynamic system. The reaction parameters were obtained from previously reported research. In the IKKb QSAR model, good cross-validated $q^2$ (0.782) and conventional $r^2$ (0.808) values demonstrated the correlation between the descriptors and each of their activities and reliably predicted the $IKK{\beta}$ activities. Using a developed simulation model of the NF-${\kappa}B$ signaling pathway, we demonstrated differences in $I{\kappa}B$ mRNA expression between normal and different inhibitory states. When the inhibition efficiency increased, inhibitor 1 (PS-1145) led to long-term oscillations. The combined computational modeling and NF-${\kappa}B$ dynamic simulations can be used to understand the inhibition mechanisms and thereby result in the design of mechanism-based inhibitors.

• Elastomers and Composites
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• v.44 no.1
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• pp.34-40
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• 2009

New coupling agent or surface modified agent (9-decenoic acid) was used to enhance the compatibility between silica and polystyrene in silica/polystyrene hybrid nanocomposite, synthesized by in situ miniemulsion polymerization. Composites contain well dispersed nanosize silica particles. Related tests and analyses confirmed the success of synthesis. Functionalization of silica by 9-decenoic acid and silica on the polystyrene was confirmed by FTIR. TGA showed presence and amount of silica in final latex. The glass transition temperature of the hybrid nanocomposite was increased with the silica amount. SEM and TEM analysis showed the spherical morphology of PS and composite with an average diameter of 55 nm. The presence of silica within composite was confirmed by EDS attached to the existing TEM.