• Korean Journal of Materials Research
• /
• v.20 no.8
• /
• pp.434-438
• /
• 2010

The selenization process has been a promising method for low-cost and large-scale production of high quality CIGS film. However, there is the problem that most Ga in the CIGS film segregates near the Mo back contact. So the solar cell behaves like a $CuInSe_2$ and lacks the increased open-circuit voltage. In this study we investigated the Ga distribution in CIGS films by using the $Ga_2Se_3$ layer. The $Ga_2Se_3$ layer was applied on the Cu-In-Ga metal layer to increase Ga content at the surface of CIGS films and to restrict Ga diffusion to the CIGS/Mo interface with Ga and Se bonding. The layer made by thermal evaporation was showed to an amorphous $Ga_2Se_3$ layer in the result of AES depth profile, XPS and XRD measurement. As the thickness of $Ga_2Se_3$ layer increased, a small-grained CIGS film was developed and phase seperation was showed using SEM and XRD respectively. Ga distributions in CIGS films were investigated by means of AES depth profile. As a result, the [Ga]/[In+Ga] ratio was 0.2 at the surface and 0.5 near the CIGS/Mo interface when the $Ga_2Se_3$ thickness was 220 nm, suggesting that the $Ga_2Se_3$ layer on the top of metal layer is one of the possible methods for Ga redistribution and open circuit voltage increase.

• Journal of Astronomy and Space Sciences
• /
• v.34 no.4
• /
• pp.343-352
• /
• 2017

A space plasma facility has been operated with a back-diffusion-type plasma source installed in a mid-sized vacuum chamber with a diameter of ~1.5 m located in Satellite Technology Research Center (SaTReC), Korea Advanced Institute of Science and Technology (KAIST). To generate plasma with a temperature and density similar to the ionospheric plasma, nickel wires coated with carbonate solution were used as filaments that emit thermal electrons, and the accelerated thermal electrons emitted from the heated wires collide with the neutral gas to form plasma inside the chamber. By using a disk-type Langmuir probe installed inside the vacuum chamber, the generation of plasma similar to the space environment was validated. The characteristics of the plasma according to the grid and plate anode voltages were investigated. The grid voltage of the plasma source is realized as a suitable parameter for manipulating the electron density, while the plate voltage is suitable for adjusting the electron temperature. A simple physical model based on the collision cross-section of electron impact on nitrogen molecule was established to explain the plasma generation mechanism.

• Korean Chemical Engineering Research
• /
• v.56 no.5
• /
• pp.679-686
• /
• 2018

Reverse osmosis (RO) concentration of sodium chloride, sodium acetate, and sodium citrate solutions has been performed by polyamide RO membrane. Concentration polarization phenomena was also studied by changing pressure, solute kinds, and initial solution concentration. Pressure effect on permeation flux was that the increase of flux was accompanied by the increase of pressure. Flux increase was observed by the decrease of initial solution concentration. Surface concentration on the RO membrane increases and so flux declines due to the concentration polarization. In the later phase of concentration, concentration polarization effect was decreased by the back diffusion of solute from the polariztion layer. In case of sodium citrate, its large ion size and charge density resulted in the discrepancy between theory and experimental data of concentration polarization. It may be due to electric repulsion on the membrane surface.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.21 no.4
• /
• pp.1030-1033
• /
• 2007

Following conclusions about Taeyang meridian and Taeyang type were obtained through studies with reference to the books of ${\ll}$Donguibogam${\gg}$, ${\ll}$Hwangjaenaegyung${\gg}$, and ${\ll}$Special Lectures of Master Jisan on Medical cases${\gg}$ . Park noticed that there was difference in the development of 12 meridians among the individuals and tried to apply it in the diagnosis and the treatment of the disease, thereby creating the theory of the six meridian types. The literal basis is assumed to a phrase in ${\ll}$YoungChu GyungMaek${\gg}$ , ‘人經不同 絡脈異所別也’. Taeyang meridian runs through the back of the human body. The concept of TaeYang includes surface, starting point, diffusion of Yang Gi, and emission. Small intestine meridian of hand Taeyang manages the liquid and Bladder meridian of foot Taeyang manages the muscle. There is much flow of blood and less of Gi in Taeyang meridian which makes the connection to hair, flesh, liquid, muscle and vessel. Taeyang conceals and condenses objects because it belongs to Hansu according to division of Six atmospheric influences and to the winter. The articulation is stiff and urination and elimination are abnormal when disease occurs in this meridian. The pathology of Taeyang meridian would be the invasion of outer filthy Gi affecting the Bladder meridian of foot Taeyang which then again makes Kidney meridian of foot Soeum sick. The two meridians compose the outer part and the inner part of th body. The bladder itself becomes sick sometimes. The condition of less Gi in Taeyang meridian can easily result in the shortage of Gi, and much blood makes the person to have a lofty ideal or to have capricious behavior.

• Journal of the Institute of Convergence Signal Processing
• /
• v.11 no.4
• /
• pp.326-331
• /
• 2010

This paper has proposed and experimentally demonstrated a new BLU using an LED and an acryl, which is specially focused on the implementation about the guiding effect of an acryl luminous by the LED. While the conventional BLU using a fluorescent lamp is generally and widely used, it shows big power consumption with a short life even more too thick to hold on the wall. To solve such demerits, we propose a new method for a BLU using an LED and an acryl in this paper. This BLU system has various scratches on the surface of acryl to get diffusion effect of light, and has been included an embedded board that can dynamically control the colors and the intensity of the BLU through the Internet. We have conducted computer simulations to find out the optimal scratch pattern on the surface of the acryl for the backlight system. Based on the resulted out simulation. The the optimal scratch pattern signs has been developed. The simulation result shows 2,673Lux an average for a luminous intensity test, and the other hand, experiential result shows 2,554Lux. From the experiments, it is possible for the proposed BLU system to be used for real advertisements.

• Environmental and Resource Economics Review
• /
• v.30 no.1
• /
• pp.27-48
• /
• 2021

We extend and modify the canonical epidemiology model of Eichenbaum, Rebelo and Trabandt (2020) to investigate the general equilibrium effects of COVID-19 spread in the Korean economy when vaccine, treatment and social distancing are available. Particularly, we develop a SIR-macro model which considers possibility of moral inattention of the overconfident agents through which people is more likely to be infected. Our model implies that people's decision to cut back on consumption and work reduces the severity of the epidemic and thus exacerbate the size of the economic recession caused by the epidemic. Another finding is that the average 13 weeks to develop the vaccine and treatment will lead to 2% drop of consumption.

• Applied Chemistry for Engineering
• /
• v.34 no.3
• /
• pp.272-278
• /
• 2023

In this study, we analyzed the effects of current density and electroosmotic phenomena on the desalination performance of electrodialysis (ED). We conducted ED experiments under constant voltage conditions, changing the concentration of the concentrate solution from 10 to 200 g/L. During the ED operation, we measured the current density and charge supplied to the stack, the concentration of the diluted and concentrated solutions, and the amount of water transported by electroosmosis to analyze desalination performance. As the concentration of the concentrated solution increased, the selectivity of the ion exchange membrane decreased, resulting in a decrease in current efficiency. Moreover, the current efficiency was found to be influenced by the current density supplied. When the current density exceeded 15 mA/cm², back diffusion of ions was suppressed, leading to an increase in current efficiency. We also investigated the specific water transport by electroosmosis during the ED operation. We found that the amount of water transported increased proportionally to the concentration ratio of the concentrated and diluted solutions. When the concentration ratio exceeded 100, the specific water transport rapidly increased due to osmotic pressure, making it challenging to obtain a concentrated solution greater than 200 g/L.

• Journal of Electrochemical Science and Technology
• /
• v.14 no.2
• /
• pp.184-193
• /
• 2023

This study investigates the effects of a carbon fiber layer formed on the surface of an etched aluminum current collector on the electrochemical properties of the activated carbon electrodes for an electric double layer capacitor. A particle size analyzer, field-emission SEM, and nitrogen adsorption/desorption isotherm analyzer are employed to analyze the structure of the carbon fiber layer. The electric and electrochemical properties of the activated carbon electrodes using a carbon fiber layer are evaluated using an electrode resistance meter and a charge-discharge tester, respectively. To uniformly coat the surface with carbon fiber, we applied a planetary mill process, adjusted the particle size, and prepared the carbon paste by dispersing in a binder. Subsequently, the carbon paste was coated on the surface of the etched aluminum current collector to form the carbon under layer, after which an activated carbon slurry was coated to form the electrodes. Based on the results, the interface resistance of the EDLC cell made of the current collector with the carbon fiber layer was reduced compared to the cell using the pristine current collector. The interfacial resistance decreased from 0.0143 Ω·cm² to a maximum of 0.0077 Ω·cm². And degradation reactions of the activated carbon electrodes are suppressed in the 3.3 V floating test. We infer that it is because the improved electric network of the carbon fiber layer coated on the current collector surface enhanced the electron collection and interfacial diffusion while protecting the surface of the cathode etched aluminum; thereby suppressing the formation of Al-F compounds.

• Journal of radiological science and technology
• /
• v.34 no.3
• /
• pp.239-244
• /
• 2011

In this study, we evaluated diffusion weighted imaging (DWI) to investigate whether the DWI parameters can predict characteristic parameters on pathologic specimens of tumor or not. CFPAC-1 was injected subcutaneously on the back flank of athymic nude mice (n=13) then two tumors were initiated on each mouse (2${\times}$13=26 tumors). The mice were sacrificed to make specimen immediately after initial MR imaging then were compared with the MR image. A dedicated high-field (7T) small-animal MR scanner was used for image acquisitions. A T1 and T2 weighted axial image using RARE technique was acquired to measure the T2 values and tumor size. DWI MR was performed for calculating ADC values. To evaluate tumor cellularity and determine the levels of MVD, tumor cells were excised and processed for H-E staining and immunostaining using CD31. T2 values and ADC values were computed and analyzed for each half of the tumors and compared to the correlated specimens slide. Median ADC within each half of mass was compared to the cellularity and MVD in the correlated area of pathologic slide. The mean of ADC value is $0.7327{\times}10^{-3}$ $mm^2/s$ and standard deviation is $0.1075{\times}10^{-3}$ $mm^2/s$. There is a linear relationship between ADC value and tumor necrosis (R2=0.697, p< 0.001). DW image parameters including the ADC values can be utilized as surrogate markers to assess intratumoral neoangiogenesis and change of the internal structure of tumor cells.

• Archives of Plastic Surgery
• /
• v.37 no.3
• /
• pp.213-219
• /
• 2010

Purpose: Iodine has been used for the prevention or management of wound infection as a topical agent. Although iodine was widely used mainly by Betadine$^{(R)}$ and cadexomer iodine, there was no comparative study on the efficacies of dressing methods of iodine. And also it's wound healing effect was not yet clear. The purpose of this study is to compare antibacterial effects and wound healing effects associated with various dressing methods of iodine on infected full thickness skin defect in the mouse. Methods: One full thickness skin defects in the mice (n=60) were developed on the back and left open for twenty-four hours. Sixty mice were divided into four groups : group S (dressing with Betadine$^{(R)}$ soaking, n=15), group T (dressing with Betadine$^{(R)}$ topping, n=15), group I (dressing with Iodosorb$^{(R)}$, n=15), group G (control group, dressing with dry gauze, n=15). The size of the wound defects and the grades of wound healing were evaluated in 4, 7, 10 days, and antibacterial effect was evaluated with restricted zone in Mueller Hinton agar by disk diffusion method. Results: After the wound was left open for twenty-four hours, many Staphylococcus aureus were cultured. The wound defect size was decreased in order of Betadine$^{(R)}$ soaking, Iodosorb$^{(R)}$, Betadine$^{(R)}$ topping and gauze dressing group in all days, but difference among experimental groups was not statistically significant. The grade score of wound healing was increased in order of Betadine$^{(R)}$ soaking, Iodosorb$^{(R)}$, Betadine$^{(R)}$ topping and gauze dressing group, and the difference was statistically significant. Antibacterial effect for S. aureus was increased in order of Iodosorb$^{(R)}$, Betadine$^{(R)}$ soaking, Betadine$^{(R)}$ topping and gauze dressing group, and the difference was statistically significant. Conclusion: Selection of the effective dressing method of iodine for infected wounds remains a controversial decision. According to this study, Iodosorb$^{(R)}$ may be most effective method for antibacterial effect and Betadine$^{(R)}$ soaking may be most effective method for infected wound healing. However, further study is necessary to evaluate the clinical efficacy of dressing methods of iodine and to search for the mechanisms that explain their effects.