• Biomolecules & Therapeutics
• /
• v.27 no.6
• /
• pp.577-583
• /
• 2019

Human cytochrome P450 2C9 is a highly polymorphic enzyme that is required for drug and xenobiotic metabolism. Here, we studied eleven P450 2C9 genetic variants-including three novel variants F69S, L310V, and Q324X-that were clinically identified in Korean patients. P450 2C9 variant enzymes were expressed in Escherichia coli and their bicistronic membrane fractions were prepared The CO-binding spectra were obtained for nine enzyme variants, indicating P450 holoenzymes, but not for the M02 (L90P) variant. The M11 (Q324X) variant could not be expressed due to an early nonsense mutation. LC-MS/MS analysis was performed to measure the catalytic activities of the P450 2C9 variants, using diclofenac as a substrate. Steady-state kinetic analysis revealed that the catalytic efficiency of all nine P450 2C9 variants was lower than that of the wild type P450 2C9 enzyme. The M05 (R150L) and M06 (P279T) variants showed high $k_{cat}$ values; however, their $K_m$ values were also high. As the M01 (F69S), M03 (R124Q), M04 (R125H), M08 (I359L), M09 (I359T), and M10 (A477T) variants exhibited higher $K_m$ and lower $k_{cat}$ values than that of the wild type enzyme, their catalytic efficiency decreased by approximately 50-fold compared to the wild type enzyme. Furthermore, the novel variant M07 (L310V) showed lower $k_{cat}$ and $K_m$ values than the wild type enzyme, which resulted in its decreased (80%) catalytic efficiency. The X-ray crystal structure of P450 2C9 revealed the presence of mutations in the residues surrounding the substrate-binding cavity. Functional characterization of these genetic variants can help understand the pharmacogenetic outcomes.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1491-1492
• /
• 2011

In this study, we investigated about the effect of hole transport layer materials(${\alpha}$-NPD, TPD) depending on the electrical properties of organic light emitting diode. In deposition method, we used thermal evaporation and it was a method for performing thin film by attaching vaporizing a molecule to substrate in a high thermal and vaccum. We analyzed luminance, current density, external quantum efficiency and current efficiency in 40 [nm] as optimization thickness of ${\alpha}$-NPD and TPD. In result of experiment, maximum luminance of TPD had 1.1 times higher than ${\alpha}$-NPD, but ${\alpha}$-NPD had luminance, external quantum efficiency, and current efficiency higher than TPD in low operating voltage. Actually, ${\alpha}$-NPD had efficiency higher than TPD in low operating voltage.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.461-462
• /
• 2005

In order to improve the efficiency of dye-sensitized solar cell (DSC), $TiO_2$ electrode screen-printed on transparent conducting oxide (TCO) substrate was sintered in variation with different temperature(350 to $550^{\circ}C$). $TiO_2$ electrode on fluorine doped tin oxide (FTO) glass was assembled with Pt counter electrode on FTO glass. I-V properties of DSC were measured under solar simulator. Also, effect of sintering temperature on surface morphology of $TiO_2$ films was investigated to understand correlation between its surface morphology and sintering temperature. Such surface morphology was observed by atomic force microscopy (AFM). From the measurement results, at sintering temperature of $500^{\circ}C$, both efficiency and fill factor of DSC were mutually complementary, enhancing highest fill factor and efficiency. Consequently, it was considered that optimum sintering temperature of $\alpha$-terpinol included $TiO_2$ paste is at $500^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.1
• /
• pp.47-52
• /
• 2019

Micro-LEDs show lower efficiencies compared to general LEDs having large areas. Simulations were carried out using ray-tracing software to investigate the change in light extraction efficiency and light distribution according to chip-size of blue flip-chip micro-LEDs (FC ${\mu}-LEDs$). After fixing the height of the square FC ${\mu}-LED$ chip at $158{\mu}m$, the length of one side was varied, with dimensions of 2, 5, 10, 30, 50, 100, 300, and $500{\mu}m$. The highest light-extraction efficiency was obtained at $10{\mu}m$, beyond which the efficiency decreased as the chip-size increased. The chip size-dependence of the FC ${\mu}-LEDs$ both without the patterned sapphire substrate, as well as vertical FC ${\mu}-LEDs$, were analyzed.

• Journal of Electrical Engineering and Technology
• /
• v.1 no.2
• /
• pp.233-236
• /
• 2006

A 3-D numerical simulation of a buried-channel CCD (Charge Coupled Device) with a deep depletion has been performed to investigate its electrical and physical behaviors. Results are presented for a deep depletion CCD (EEV CCD12; JET-X CCD) fabricated on a high-resistivity $(1.5k\Omega-cm)\;65{\mu}m$ thick epi-layer, on a $550{\mu}m$ thick p+ substrate, which is optimized for X-ray detection. Accurate predictions of the Potential minimum and barrier height of a CCD Pixel as a function of mobile electrons are found to give good charge transfer. The depletion depth approximation as a function of gate and substrate bias voltage provided average errors of less than 6%, compared with the results estimated from X-ray detection efficiency measurements. The result obtained from the transient simulation of signal charge movement is also presented based on 3-Dimensional analysis.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.387.2-387.2
• /
• 2016

Glass texturing is a sufficient method for changing the surface morphology to enhance the light trapping. In this study, glass texturing was applied to the perovskite solar cell for improving the current density. Glass substrates (back-side glass of FTO coated glass substrate) were textured by randomly structure assisted wet etching process using diluted HF solution at a constant concentration of etchants (HF:H2O=1:1). Then, the light trapping properties of suitable films were controlled over a wide range by varying the etching time (1, 2, 3, 4 and 5 min.). The surface texturing changed the reflected light in an angle that it can be reflected by substrate glass surface. As a result, Current density and cell efficiency were affected by light trapping layer using glass texturing method in perovskite solar cells.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.703-706
• /
• 1998

This paper presents an efficient substrate-bias generator(SBG)for low-power, high-density DRAM's The proposed SBG can supply stable voltage with switching the supply voltage of driving circuit, and it can substitude the small capacitance for the large capacitance. The charge pumping circuit of the SBG suffere no VT loss and is to be applicable to low-voltage DRAM's. Also it can reduce the power consumption to make VBB because of it's high pumping efficiency. Using biasing voltage with positive temperature coefficient, VBB level detecting circuit can detect constant value of VBB against temperature variation. VBB level during VBB maintaining period varies 0.19% and the power dissipation during this period is 0.16mw. Charge pumping circuit can make VBB level up to -1.47V using VCC-1.5V, and do charge pumping operation one and half faster than the conventional ones. The temperature dependency of the VBB level detecting circuit is 0.34%. Therefore the proposed SBG is expected to supply a stable VBB with less power consumption when it is used in low power DRAM's.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.398-401
• /
• 2008

Inkjet printing is commonly used in the controlled deposition of solutions of functional materials in specific locations on a substrate, and it can provide easy and fast deposition of polymer films over a large area. which could become a way to manufacturer low cost solar cells. In the present study, inkjet printing technology is adopted to deposit functional layers of PEDOT/PSS solutions and P3HT/PCBM blends for organic solar cell. The results show that merging of separately deposited ink droplets into a continuous, pinhole-free organic thin film could be achieved by a balance between ink property and substrate treatment. As a result, a power conversion efficiency of 2.0% has been accomplished a solar cells applying inkjet technology.

• Vacuum Magazine
• /
• v.4 no.3
• /
• pp.16-20
• /
• 2017

Graphene has emerged as a promising material for optoelectronic applications including as ultrafast and broadband photodetector, optical modulator, and nonlinear photonic devices. Graphene based devices have shown the feasibility of ultrafast signal processing for required for photonic integrated circuits. However, on-chip monolithic nanoscale light source has remained challenges. Graphene's high current density, thermal stability, low heat capacity and non-equilibrium of electron and lattice temperature properties suggest that graphene as promising thermal light source. Early efforts showed infrared thermal radiation from substrate supported graphene device, with temperature limited due to significant cooling to substrate. The recent demonstration of bright visible light emission from suspended graphene achieve temperature up to ~3000 K and increase efficiency by reducing the heat dissipation and electron scattering. The world's thinnest graphene light source provides a promising path for on-chip light source for optical communication and next-generation display module.

• Journal of the Korean Vacuum Society
• /
• v.6 no.S1
• /
• pp.59-65
• /
• 1997

Efficient Si(100) etching by thermal H atoms at low substrate temperatures has been achieved. Gas-phase etching product $SiH_4$(g) upon H atom bombardment resulting from direct abstraction of $SiH_3$(a) by impinging H atoms was detected with a quadrupole mass spectrometer over the substrate temperature range of 105-408 K Facile depletion of all surface silyl ($SiH_3$) groups the dissociative adsorption product of disilane ($Si_2H_6$) at 105K from Si(100)2$\times$1 by D atoms and continuous regeneration and removal of $SiD_3$(a) were all consumed. These results provide direct evidence for efficient silicon surface etching by thermal hydrogen bombardment at cryogenic temperatures as low as 105K We attribute the high etching efficiency to the formation and stability of $SiH_3$(a) on Si(100) at lowered surface temperatures allowing the $SiH_3$(a) abstraction reaction by additional H atom to produce $SiH_4$((g).