• Macromolecular Research
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• v.15 no.4
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• pp.343-347
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• 2007

Novel composite membranes, which delivered high separation performance for propylene/propane mixtures, were developed by coating inert poly(ethylene-co-propylene) rubber (EPR) onto a porous polyester substrate, followed by the physical distribution of $AgBF_4$. Scanning electron microscopy-wavelength dispersive spectrometer (SEM-WDS) revealed that silver salts were uniformly distributed in the EPR layer. The physical dispersion of the silver salts in the inert polymer matrix, without specific interaction, was characterized by FT-IR and FT-Raman spectroscopy. The high separation performance was presumed to stem from the in-situ dissolution of crystalline silver ionic aggregates into free silver ions, which acted as an active propylene carrier within a propylene environment, leading to facilitated propylene transport through the membranes. The membranes were functional at all silver loading levels, exhibiting an unusually low threshold carrier concentration (less than 0.06 of silver weight fraction). The separation properties of these membranes, i.e. the mixed gas selectivity of propylene/propane ${\sim}55$ and mixed gas permeance ${\sim}7$ GPU, were stable for several days.

• Journal of the Korean Ceramic Society
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• v.50 no.3
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• pp.173-179
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• 2013

Wurtzite nanomaterials, such as ZnO, GaN, and InN, have become a subject of great scientific and technological interest as they simultaneously have piezoelectric and semiconductor properties. In particular, the piezoelectric potential (piezopotential) created by dynamic straining in the nanowires drives a transient flow of current in the external load, converting mechanical energy into electricity. Further, the piezopotential can be used to control the carrier generation, transport, separation, and/or recombination at the metal-semiconductor junction or p-n junction, which is called the piezophototronic effect. This paper reviews the recent advances on the piezophototronic effect to better use the piezophototronic effect to control the carrier generation, transport, separation and/or recombination for improving the performance of optoelectronic devices, such as photon detectors, solar cells and LEDs. This paper also discusses several research and design studies that have improved the output performance of optoelectronic devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.377-377
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• 2014

We demonstrate the high temperature-dependent electrical behavior at 2D multilayer MoS2 transistor. Our previous reports explain that the extracted field-effect mobility of good device was inversely proportional to the increase of temperature. Because scattering mechanism is dominated by phonon scattering at a well-designed MoS2 transistor, having, low Schottky barrier. However, mobility at an immature our $MoS_2$ transistor (${\mu}m$ < $10cm^2V^{-1}s^{-1}$) is proportional to the increase temperature. The existence of a big Schottky barrier at $MoS_2-Ti$ junction can reduce carrier transport and lead to lower transistor conductance. At high temperature (380K), the field-effect mobility of multilayer $MoS_2$ transistor increases from 8.93 to $16.9cm^2V^{-1}sec^{-1}$, which is 2 times higher than the value at room temperature. These results demonstrate that carrier transport at an immature $MoS_2$ with a high Schottky barrier is mainly affected by thermionic emission over the energy barrier at high temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.492-496
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• 2001

Due to their better photosensitivity in X-ray, the amorphous selenium based photoreceptor is widely used on the X-ray conversion materials. It was possible to control the charge carrier transport of amorphous selenium by suitably alloying a-Se with other elements(e,g. As, Cl). In this paper, We investigated dopants(As, Cl) composition rate to improve dark resistivity and transport properties of charge carrier in amorphous selenium using by direct X-ray conversion material. Alloying a-Se with As inhibits the recrystallization of a-Se but introduces undesirable deep hole traps. then doping with Cl(in the ppm range) compensates for the deep hole traps. We investigated their composition rate in various doping conditions and then obtained optimum dopant composition rate. The result was Se-As 0.3%-c] 30 ppm and X-ray Sensitivity was 0.57 pC/$pixel{\cdot}mR$ at $137{\mu}m{\times}137{\mu}m$ Pixel area.

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.52-62
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• 1990

Cationic polycarbonate type polyurethane was prepared from the quaternization reaction of N-methyldiethanolamine(MDEA) in urethane backbone which was obtained from the reaction of polycarbonate polyol, MDI and MDEA(chain exetender). Tensile strength and modulus of the cationic urethane resins were increased sharply with increasing the ionic content in urethane backbone. But hydrolysis resistance was decreased with increasing ionic contents. The selectivity of the cationic polycabonate urethane membrane for water/ethanol separation by pervaporation was about 20. The carrier mediated transport mechanism was considered the most probable separation mechanism for these membranes.

• Journal of Magnetics
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• v.13 no.3
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• pp.88-91
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• 2008

This study examined the effect of Sn co-doping on the transport and magnetic properties of Cr-doped $In_2O_3$ thin films grown on (100) silicon substrates by pulsed laser deposition. The experimental results showed that Sn co-doping enhances the magnetization and appearance of the anomalous Hall effect, and increases the carrier (electron) concentration. These results suggest that the conduction carrier plays an important role in enhancing the ferromagnetism of a laser-deposited Cr-doped $In_2O_3$ film, which may have applications in transparent oxide semiconductor spin electronics devices.

• Environmental Engineering Research
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• v.25 no.3
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• pp.418-425
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• 2020

In this study soft computing techniques including, Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) were investigated for the prediction of Cr(VI) transport efficiency by novel Polymer Inclusion Membranes (PIMs). Transport experiments carried out by varying parameters such as time, film thickness, carrier type, carier rate, plasticizer type, and plasticizer rate. The predictive performance of ANN and ANFIS model was evaluated by using statistical performance criteria such as Root Mean Standard Error (RMSE), Mean Absolute Error (MAE), and Coefficient of Determination (R²). Moreover, Sensitivity Analysis (SA) was carried out to investigate the effect of each input on PIMs Cr(VI) removal efficiency. The proposed ANN model presented reliable and valid results, followed by ANFIS model results. RMSE and MAE values were 0.00556, 0.00163 for ANN and 0.00924, 0.00493 for ANFIS model in the prediction of Cr(VI) removal efficiency on testing data sets. The R² values were 0.973 and 0.867 on testing data sets by ANN and ANFIS, respectively. Results show that the ANN-based prediction model performed better than ANFIS. SA demonstrated that time; film thickness; carrier type and plasticizer type are major operating parameters having 33.61%, 26.85%, 21.07% and 8.917% contribution, respectively.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.1
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• pp.28-38
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• 2024

Due to globalization, the air transport industry plays a key role in the global economy. In particular, the air transport industry is highly dependent on human resources, and the capabilities of the cabin crews in managing safety and providing service in a cabin depend on the service quality and the success of the company's human resource management. Therefore, systematic support and interest in competitive key personnel are believed as very important factors. Airlines need to improve the work engagement of airline cabin crew through organizational supportive efforts. Thus this paper surveyed 309 cabin crews who worked at low cost carrier and conducted an empirical analysis based on survey results. The study validates hypotheses pertaining the relationship between organizational identification and job commitment of cabin crew according to the airline's perception of organizational support. The comprehensive analysis reveals that perceived organization support has a significantly positive impact on cabin crews' work engagement.

• Journal of the Korean Society of Radiology
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• v.16 no.2
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• pp.141-150
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• 2022

The initial co-transport and counter-transport permeate transport characteristics of calcium ion at epithelial cell membrane model in parathyroid which irradiated by high energy x-ray(linac 6 MV) was investigated. The epithelial cell membrane model used in this experiment was a polysulfonated copolymerized membrane of poly(PS-DVB: polystyrene-divinylbenzene). The difference of sorbed water in membrane, fixed carrier concentration(SO₃^2-), initial pH value, OH^- concentration were occurred at difference of Ca²⁺concentration and quantity of parathyroid hormone, respectively. The initial co-transport and counter-transport permeate flux of Cl^-, OH^-, Ca²⁺ on fixed carrier concentration(SO₃^2-) and initial pH value of irradiated membrane was found to be decreased than non-irradiated membrane. The initial co-transport and counter-transport permeate flux of Ca²⁺ on fixed carrier concentration (SO₃^2-), initial pH value, OH^- concentration in irradiated membrane were found to be decreased about 2.68 ~ 6.87 times, about 1.42 ~ 1.63 times, about 2.07 ~ 1.672 times than non-irradiated membrane, respectively. As a result, the quantity of parathyroid hormone was decreased at irradiated membrane than non-irradiated membrane. The decrease of parathyroid hormone was occurred at hypoparathyroidism and osteoporosis, parathyroiditis, and so on. As the parathyroid hormone in epithelial cell membrane model were abnormal, cell damages were appeared at cell.

• Journal of the Korean Applied Science and Technology
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• v.20 no.2
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• pp.154-164
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• 2003

This paper has applied a simple model to the mass transfer mechanism of Cr(VI) with crownether in a batch-type, supported liquid membrane module. Concentration at pH 3 are as follows : 0.012 kmol/$m^3{\le}$18-crown-6${\le}$0.036 kmol/$m^3$ and 20 g/$m^3{\le}$ Cr(VI)${\le}$500 g/$m^3$. The measured values of forward- and backward-reaction rate constants between Cr(VI) and 18-crown-6 were used to simulate the model with the mass conservation equation and associated boundary conditions. Comparison between the experimental and simulated facilitated factor of Cr(VI) transport led to classification of reaction regions.