• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.156-156
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• 2011

Nanocrystalline $Ca_2Gd_8Si_6O_{26}$ (CGS) : $Sm^{3+}$ and CGS : $Tb^{3+}/Sm^{3+}$ phosphors were prepared by solvothermal reaction method for light emitting diode (LED) and field emission display (FED) applications. The XRD patterns of these phosphors confirmed their oxyapatite structure in the hexagonal lattice. The visible luminescence properties of these phosphors were investigated by exciting with ultraviolet (UV) or near-UV light and low voltage electron beam. The photoluminescence (PL) properties of $Ca_2Gd_8Si_6O_{26}$ (CGS) : $Sm^{3+}$ and CGS : $Tb^{3+}/Sm^{3+}$ phosphors were investigated as a function of $Sm^{3+}$ concentration. Cathodoluminescence (CL) properties were examined by changing the acceleration voltage. The CGS : $Sm^{3+}$ showed the dominant orange emission due to the $^4G_{5/2}{\rightarrow}^6H_{7/2}$ transition. The CGS : $Tb^{3+}/Sm^{3+}$ phosphor showed the green, white and orange emissions when excited with 275, 378, and 405 nm wavelengths, respectively. The chromaticity coordinates of these phosphors were comparable to or better than those of standard phosphors for LED or FED devices.

• Current Optics and Photonics
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• v.4 no.5
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• pp.428-433
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• 2020

Recently, the on-chip autofocus (AF) function has become essential to the CMOS image sensor. An auto-focus usually operates using phase detection of the photocurrent difference from a pair of AF pixels that have focused or defocused. However, the phase-detection method requires a pair of AF pixels for comparison of readout. Therefore, the pixel variation may reduce AF performance. In this paper, we propose a color-selective AF pixel with a plasmonic nanostructure in a 0.9 μ㎡ pixel. The suggested AF pixel requires one pixel for AF function. The plasmonic nanostructure uses metal-insulator-metal (MIM) stack arrays instead of a color filter (CF). The color filters are formed at the subwavelength, and they transmit the specific wavelength of light according to the stack period and incident angles. For the optical analysis of the pixel, a finite-difference time-domain (FDTD) simulation was conducted. The analysis showed that the MIM stack arrays in the pixels perform as an AF pixel. As the primary metric of AF performance, the resulting AF contrasts are 1.8 for the red pixels, 1.6 for green, and 1.5 blue. Based on the simulation results, we confirmed the autofocusing performance of the MIM stack arrays.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.654-654
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• 2013

One of the most important yet unresolved problems in molecular electronics is the controversy over the number and nature of multiple conductance peaks in single-molecule junctions. Currently, there are three competing explanations of this observation: (1) manifestation of different molecule-electrode contact geometries, (2) formation of gauche defects within the molecular core, (3) involvement of different electrode surface orientations [1]. However, the exact origin of multiple conductance peaks is not yet fully understood, which indicates our incomplete understanding of the scientifically as well as techno-logically important organic-metal contacts. To theoretically resolve this problem, we previously applied a multiscale computational approach that combines force fields molecular dynamics (FF MD), density functional theory (DFT), and matrix Green's function (MGF) calculations [2] to a thermally fluctuating haxanedithiol (C6DT) molecule stretched between flat Au(111) electrodes, but could observe only a single conductance peak [3]. In this presentation, using DFT geometry optimizations and MGF calculations, we consider molecular junctions with more realistic molecule-metal contact conformations and Au(111) electrode surface directions. We also conduct DFT-based molecular dynamics for the highly stretched junction models to confirm our conclusion. We conclude that the S-Au coordination number should be the more dominant factor than the electrode surface orientation.

• Journal of the Korean institute of surface engineering
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• v.44 no.2
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• pp.68-73
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• 2011

A Ni-W thin-film was synthesized by electrodeposition, and its corrosion resistance and electrical surface conductivity were investigated. Amount of tungsten in the Ni-W thin-film increased linearly with current density during the electrodeposition, and crack-free and low-crystalline Ni-21 at.%W coating layer was obtained. Corrosion resistances of the Ni-W thin-films were examined with an anodic polarization method and a storage test in a strong sulfuric acid solution. As a result, the Ni-21 at.%W thin-film exhibited the greatest corrosion resistance, and maintained the electrical surface conductivity even after the severe corrosion test, which could be applicable as a surface treatment for advanced metallic bipolar plates in fuel cell or redox flow battery systems.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.8
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• pp.22-29
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• 1996

This study describes a method to find the torso surface potential based on the boundary element method. In order to find the torso surface potential, the governing equation was developed based on the green's second theorem. The boundary element method (BEM) which has a good computing capability in case of homogeneous and isotropic medium was applied to solve the equation. to validate the BEM, we considered a homogeneous sphere model which has an electrric dopole source inside. The results showed the good agreement between the analytic solution and the computed solution. In normal heart, the simulated torso surface isopotential maps are good agreement with that obtained form the ventricular excitation.

• ETRI Journal
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• v.35 no.4
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• pp.632-637
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• 2013

In this paper, we propose a superjunction trench gate MOSFET (SJ TGMOSFET) fabricated through a simple p-pillar forming process using deep trench and boron silicate glass doping process technology to reduce the process complexity. Throughout the various boron doping experiments, as well as the process simulations, we optimize the process conditions related with the p-pillar depth, lateral boron doping concentration, and diffusion temperature. Compared with a conventional TGMOSFET, the potential of the SJ TGMOSFET is more uniformly distributed and widely spread in the bulk region of the n-drift layer due to the trenched p-pillar. The measured breakdown voltage of the SJ TGMOSFET is at least 28% more than that of a conventional device.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.327-331
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• 2014

LED(Light Emitting Diode) is a semiconductor device utilizing electroluminescent effect is a phenomenon in which a type of P-N junction diode, the light of short wavelength which a voltage is applied in the forward direction is released. LED is advantageous in reducing the energy as environmentally materials that can greatly reduce the carbon emissions, recent it has attracted attention IT(Information Technology) and GT(Green Technology) industry. In addition, there are advantages long life, high efficiency, and excellent response speed, LED have come into the spotlight as the illumination means to replace the existing fluorescent light and incandescent light bulb. When connecting to MR16 electronic transformer for existing LED driver circuit, due to malfunction of the dimmer and the electronic transformer, flicker occurs and linear dimming is not possible. Therefore, in this paper, we suggest an LED drive circuit there is no flicker with the corresponding dimming MR16 electronic transformer. Further, we explain the principles of the LED current control technique and the principle of the drive circuit of the LED, in order to validate the proposed circuit through prototyping and simulation.

• Electronics and Telecommunications Trends
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• v.36 no.1
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• pp.109-119
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• 2021

The Korean government recently announced a plan of the Carbon Neutral policy in addition to the Green New Deal of the Korean New Deal and the Renewable Energy 3020. The energy sector is entering the era of major transformation involving the expansion of decarbonization, decentralization, and digitalization. DNA-oriented ICT technology will be incorporated into the sector. Further, new energy industries and services are being realized via efficient and smart operation and by appropriately managing the energy-environment changes. Recently, ETRI presented a technology development map for 2035 comprising 12 new concepts in four major fields(personal, social, industrial and public) of national intelligence. This map includes the concept of "Energy Maestro" associated with the field of public intelligence for human sustainability. This paper briefly introduces this concept and ETRI's Energy-R&D status. Based on the domain knowledge and the experience acquired through the R&D, ETRI will lead to a new paradigm with respect to the creation of new energy services and industries via the incorporation of the new ICT technologies including AI and big-data into the energy sector.

• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.85-92
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• 2023

The hardware of an LED lighting control system for coastal lighting at coastal pier entrance consists of a power supply unit, an AVR control unit, a CLCD output unit, an LED control unit, a scenario selection switch unit, and an operation speed display unit. It is made of an 8-channel. The CPU used ATmega128 and the FET was used to control the current signal. To operate the CPU, DC 12V was converted to DC 5V using a regulator 7805. A heat sink was used to remove heat generated in the FET. By connecting the load LED module to the manufactured 8-channel LED lighting control system, the operation was confirmed through various production scenarios. In addition, a control system was designed to show the most suitable color for the atmosphere of the coastal pier according to the input value of temperature and illumination using a fuzzy control system. Computer simulation was then conducted. Results confirmed that fuzzy control did not need to store many data inputs due to characteristics of artificial intelligence and that it could efficiently represent many output values with simple fuzzy rules.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.275-279
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• 2023

La_0.7Sr_0.3-xMg_xMnO₃ (LSMMO) (x=0.05~0.20) specimens are fabricated by a solid phase sintering method, and the sintering temperature and time are 1,300℃ and 2 hours, respectively. The dependence of the crystalline structure according to the amount of Mg²⁺ contents is not observed, and all specimens show a polycrystalline rhombohedral crystal structure, the X-ray diffraction (110) peaks move to the high angle side with increasing the amount of Mg²⁺ contents. LSMMO specimens exhibit a granule-shaped microstructure with an average grain size of 1 ㎛ or less. Resistivity gradually decrease as the amount of Mg²⁺ contents increased. And in the La_0.7Sr_0.1Mg_0.2MnO₃ specimen, resistivity and B_25/65-value are 36.7 Ω-cm and 394 K at room temperature, respectively. LSMMO specimens show a variable-range hopping (VRH) electrical conduction mechanism, and the negative temperature of coefficient of resistance (NTCR) is approximately 0.37~0.38%/℃.