• Progress in Medical Physics
• /
• v.33 no.4
• /
• pp.63-71
• /
• 2022

Purpose: To clarify the relationship between the diameter of the simulated bead and the Z-resolution of the tomosynthesis image. Methods: A simulated bead was placed on a 1,024×1,024×1,024-pixel base image. The diameters were set to 0.025, 0.05, 0.1, 0.2, 0.3, 0.7, 1.0, and 1.3 mm. A bead was placed at the center of the base image and projected at a simulated X-ray angle range of ±45° to obtain a projected image. A region of interest was placed at the center of the bead image and the slice sensitivity profile (SSP) was obtained by acquiring pixel values in the z-direction. The full width at half maximum of the SSP was defined as the Z-resolution and the frequency response was obtained by the 1-D Fourier transform of the SSP. Results: Z-resolution increased with increasing bead diameter. However, there was no change in Z-resolution between 0.025 and 0.1 mm. The frequency response was similar to that of the Z-resolution, with a significant difference between 0.1 and 0.2 mm diameter. Conclusions: Z-resolution is dependent on the diameter of the bead, which should be selected considering the pixel size of the tomosynthesis image.

• Journal of Convergence for Information Technology
• /
• v.11 no.12
• /
• pp.1-13
• /
• 2021

This study tried to suggest ways to improve the indicator system to strengthen the personal information protection. For this purpose, the components of indicator system are derived through domestic and foreign literature, and it was selected as main the diagnostic indicators through FGI/Delphi analysis for personal information protection experts and a survey for personal information protection officers of public institutions. As like this, this study was intended to derive an inspection standard that can be reflected as a separate index system for personal information protection, by classifying the specific IT technologies of the 4th industrial revolution, such as big data, cloud, Internet of Things, and artificial intelligence. As a result, from the planning and design stage of specific technologies, the check items for applying the PbD principle, pseudonymous information processing and de-identification measures were selected as 2 common indicators. And the checklists were consisted 2 items related Big data, 5 items related Cloud service, 5 items related IoT, and 4 items related AI. Accordingly, this study expects to be an institutional device to respond to new technological changes for the continuous development of the personal information management level diagnosis system in the future.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.10 no.2
• /
• pp.134-142
• /
• 2010

A comparative study on the trade-off between the drive current and the total gate capacitance in double-gate (DG) and triple-gate (TG) FinFETs is performed by using 3-D device simulation. As the first result, we found that the optimum ratio of the hardmask oxide thickness ($T_{mask}$) to the sidewall oxide thickness ($T_{ox}$) is $T_{mask}/T_{ox}$=10/2 nm for the minimum logic delay ($\tau$) while $T_{mask}/T_{ox}$=5/1~2 nm for the maximum intrinsic gate capacitance coupling ratio (ICR) with the fixed channel length ($L_G$) and the fin width ($W_{fin}$) under the short channel effect criterion. It means that the TG FinFET is not under the optimal condition in terms of the circuit performance. Second, under optimized $T_{mask}/T_{ox}$, the propagation delay ($\tau$) decreases with the increasing fin height $H_{fin}$. It means that the FinFET-based logic circuit operation goes into the drive current-dominant regime rather than the input gate load capacitance-dominant regime as $H_{fin}$ increases. In the end, the sensitivity of $\Delta\tau/{\Delta}H_{fin}$ or ${{\Delta}I_{ON}}'/{\Delta}H_{fin}$ decreases as $L_G/W_{fin}$ is scaled-down. However, $W_{fin}$ should be carefully designed especially in circuits that are strongly influenced by the self-capacitance or a physical layout because the scaling of $W_{fin}$ is followed by the increase of the self-capacitance portion in the total load capacitance.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.24 no.2
• /
• pp.211-218
• /
• 2021

This paper deals with the computational work to characterize the formation and pinching of a plasma in an X-pinch configuration. A resistive magnetohydrodynamic model of a single fluid and two temperature is adopted assuming a hollow conical structure in the (r,z) domain. The model includes the thermodynamic parameter of tungsten from the corrected Thomas-Fermi EOS(equation of state), determining the average ionization charge, pressure, and internal energy. The transport coefficients, resistivity and thermal conductivity, are obtained by the corrected Lee & More model and a simple radiation loss rate by recombination process is considered in the simulation. The simulation demonstrated the formation of a core-corona plasma and intense compression process near the central region which agrees with the experimental observation in the X-pinch device at Seoul National University. In addition, it confirmed the increase in radiation loss rate with the density and temperature of the core plasma.

• Journal of the Korean Chemical Society
• /
• v.43 no.6
• /
• pp.636-643
• /
• 1999

Green-emission intensity of a $Zn_{2-x}Mn_xSiO_4$ phosphor, which is a potential candidate as a green component in PDP device, significantly increases provided that the compound is additionally heat treated at 900$^{\circ}C$ after solid state reaction at 1300$^{\circ}C$. In order to verify origin of such an intensity enhancement after the additional heat treatment in association with the electronic and local structural change at around Mn ions, the Mn K-edge X-ray absorption spectra were recorded. From the analyses of the preedge peak corresponding to $1s{\rightarrow}3d$ bound state transition and XANES spectrum, it is known that most Mn ions are in +2 oxidation state and substitute Zn ion site regardless of the thermal treatment. In addition, EXAFS analyses revealed that Mn ions formed $MnO_4$ tetrahedra with the Mn-O bond length shortened by 0.01${\AA}$ and with reduced Debye-Waller factor in the thermally treated sample.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.6
• /
• pp.28-34
• /
• 1999

We fabricated a planar ultra-violet photodetector whose ohmic and schottky contacts were respectively formed with evaporated Al and Pt on the GaN layer. To examine the applicability of the device to the UV sensor, we investigated its electrical and optical characteristics. The GaN layer on the sapphire waver had $7.8{\times}10^{16}cm^{-3}$ of doping concentnation and the $138 cm^2/V{\cdot}s$ of electron mobility and it absorbed the spectrum of the light below 325 nm wavelength. It had the responsivity of 2.8 A/W of at 325 nm, and the signal to noise ratio(SNR) of $4{\times}10^4$, and the noise equivalent power(NEP) of $3.5{\times}10^9$W under 5 V reverse bias. These results confirmed that the GaN schottky diode had a solar blind properly when it was applied to the UV photodetector.

• Korean Journal of Optics and Photonics
• /
• v.20 no.2
• /
• pp.128-133
• /
• 2009

In this paper, an optical touch panel device is newly proposed, with operating principle based on the optical coupling between a pointing pen having a built-in light source and perpendicularly crossed optical waveguide arrays. In order to enable an external light to couple into a waveguide core, the auxiliary pyramidal structures are introduced into all intersecting points located periodically along optical waveguides. The shape is optimized for minimizing the unwanted propagation loss due to the same structure by a ray tracing method. For the optical waveguide with the size of $50{\times}50{\mu}m^2$, the bottom width, height, and slope angle of the optimized pyramidal structure are $50{\mu}m$, $22.5{\mu}m$, and $42^{\circ}$, respectively. The optical coupling efficiency of about 97.8% and the average propagation loss of 0.3 dB/mm were achieved for the optimized touch panel. Finally, it is found from the tolerance analysis that tilting of the pen up to ${\pm}12^{\circ}$ can be allowed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.30 no.2
• /
• pp.111-123
• /
• 2019

In this paper, we propose a method for defining the input termination for on-wafer-type device under test (DUT) measurement. Using the newly defined input termination and noise wave correlation matrix (NWCM) measurement method based on noise power ratio, the NWCM of the on-wafer-type DUT was measured. We demonstrate a noise measurement configuration that includes wafer probes and bias tees to measure the on-wafer DUT. The S-parameter of the adapter that combines the bias tee, probe, and a line terminated by open is required to define the input termination for on-wafer DUT measurement. To measure the S-parameter of the adapter, a 2-port S-parameter measurement method using 1-port measurement is introduced. Using the measured S-parameters, a method for defining the new input termination for on-wafer-type DUT measurement is applied. The proposed method involves the measurement of the NWCM of the chip with a 1.5 dB noise figure. The noise parameters of the chip were obtained using the measured NWCM. The results indicate that the obtained values of the noise parameters are similar to those mentioned on a datasheet for the chip. In addition, repeated measurements yielded similar results, thereby confirming the reliability of the measurements.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.4
• /
• pp.343-350
• /
• 2015

The natural convection heatsink is the most commonly used cooling device, especially for high-power LED lights, because of its reliability and low long-term cost. High power LED lights are generally used in an inclined configuration for street lamps and security lamps. However, it was difficult to estimate the thermal performance of an inclined heatsink, because the results from previous studies are not applicable to the inclined configuration. In this study, we measured the thermal performance of an inclined cylindrical heatsink with plate fins. Various fin numbers, fin heights, base temperatures, and inclination angles ($30^{\circ}$ and $60^{\circ}$) were examined. Based on the experimental results, the Nusselt number correlation is presented. This correlation is applicable when the Rayleigh number, ratio of the fin height to cylinder diameter, and fin number are in the ranges 100,000-600,000, 1/6-1/2, and 9-72, respectively.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.10
• /
• pp.1532-1539
• /
• 2017

The floating photovoltaic system is a new concept in the renewable energy technology. That is similar to land based photovoltaic technology except floating system. So the system needs buoyant objects, mooring, ect, besides modules and supports, and that is able to withstand in water level changes and wind strength. Therefore the floating photovoltaic system is much different from land photovoltaic system. K-water (Korea Water Resources Corporation) has been operating two floating photovoltaic system that's capacity is 100 kW and 500 kW respectively since in summer 2011 for commercial generation, and have construction project for 2,000 kW in Boryeong multipurpose Dam and other areas. Furthermore K-water was developing a tracking-type floating photovoltaic system at Daecheong multipurpose Dam and developed and installed an ocean floating photovoltaic demonstration plant at Sihwa Lake in October 2013 for R&D. In this paper, we introduce that structure of floating photovoltaic system include buoyant structure, mooring system and auxiliary device. Especially the rope which is in part of mooring should be always maintain tension under any water level. Also we explain about structure design concept to wind load in an every loading condition and a kind of structure materials and PV structure types used in water environment. Especially ocean floating PV system is affected by tidal current and typhoon. So there are considering the elements in design. Finally we compare with floating and land photovoltaic on power amount. As a result of that we verified the floating photovoltaic system is more about 6.6~14.2 % efficiency than a general land photovoltaic system.