• Journal of Periodontal and Implant Science
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• v.34 no.3
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• pp.551-562
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• 2004

The purpose of this study was to evaluate the effects of negatively electric field on bone healing in rabbit segmental long bone defects using negatively charged PTFE membrane. Ten millimeter segmental defects in the rabbit radius were used as the experimental model. After membranes were then charge injected using a corona-charging apparatus, the left defects were covered with non charged PTFE membranes as control groups, whereas the right defect was covered with negatively charged PTFE membranes as test group. The animals were divided into 4 groups of 2 rabbits each, and sacrificed at 2, 4, 6, and 8 weeks. Histomorphometric analysis showed a more newly formed bone in negatively charged membrane at early healing period. At 2 weeks, the proportion of new bone formation to total defect area was 0.32% in control group, 1.10% in experimental group. At 4 weeks, the proportion of new bone formation to total defect area was 6.86% in control, and 13.75% in experimental. At 6 and 8 weeks, no obvious difference was found between the two groups but newly formed bone in test groups were slightly more than that in control groups. In conclusion, negatively charged membranes showed more newly bone tissue than noncharged membranes at an early healing period. Although the number of samples was small, this study showed that the combination of negatively electrical stimulation and P1FE membrane may be of value in long bone healing.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.9
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• pp.71-80
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• 2007

This paper presents a new push-push VCO technique that extracts a second harmonic output signal from a capacitive commonnode in a negativegm oscillator topology. The generation of the $2^{nd}$ harmonics is accounted for by the nonlinear current-voltage characteristic of the emitter-base junction diode causing; 1) significant voltage clipping and 2) different rising and falling time during the switching operation of core transistors. Comparative investigations show the technique is more power efficient in the high-frequency region that a conventional push-push technique using an emitter common node. Prototype 12GHz and 17GHz MMIC VCO were realized in GaInP/GaAs HBT technology. They have shown nominal output power of -4.3dBm and -5dBm, phase noise of -108 dBc/Hz and -110.4 dBc/Hz at 1MHz offset, respectively. The phase noise results are also equivalent to a VCO figure-of-merit of -175.8 dBc/Hz and -184.3 dBc/Hz, while dissipate 25.68mW(10.7mA/2.4V) and 13.14mW(4.38mA/3.0V), respectively.

• Journal of IKEEE
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• v.14 no.2
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• pp.51-57
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• 2010

A CMOS rail-to-rail high voltage buffer amplifier is proposed to drive the gamma correction reference voltage of large TFT LCD panels. It is operating by a single supply and only shows current consumption of 0.5mA at 18V power supply voltage. The circuit is designed to drive the gamma correction voltage of 8-bit or 10-bit high resolution TFT LCD panels. The buffer has high slew rate, 0.5mA static current and 1k$\Omega$ resistive and capacitive load driving capability. Also, it offers wide supply range, offset voltages below 50mV at 5mA constant output current, and below 2.5mV input referred offset voltage. To achieve wide-swing input and output dynamic range, current mirrored n-channel differential amplifier, p-channel differential amplifier, a class-AB push-pull output stage and a input level detector using hysteresis comparator are applied. The proposed circuit is realized in a high voltage 0.18um 18V CMOS process technology for display driver IC. The circuit operates at supply voltages from 8V to 18V.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.6
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• pp.89-98
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• 2005

Fingerprint segmentation and ridge orientation estimation algorithms with images from a mobile camera are proposed. The fingerprint images from a mobile camera are quite different from those from conventional sensor, called touch based sensor such as optical, capacitive, and thermal. For example, the images from a mobile camera are colored and the backgrounds or non-finger regions are very erratic depending on how the image capture time and place. Also the contrast between ridge and valley of a mobile camera image are lower than that of touch based sensor image. To segment fingerprint region, we first detect the initial region using color information and texture information. The LUT (Look Up Table) is used to model the color distribution of fingerprint images using manually segmented images and frequency information is extracted to discriminate between in focused fingerprint regions and out of focused background regions. With the detected initial region, the region growing algerian is executed to segment final fingerprint region. In fingerprint orientation estimation, the problem of gradient based method is very sensitive to outlier that occurred by scar and camera noise. To solve this problem, we propose a robust regression method that removes the outlier iteratively and effectively. In the experiments, we evaluated the result of the proposed fingerprint segmentation algerian using 600 manually segmented images and compared the orientation algorithms in terms of recognition accuracy.

• KEPCO Journal on Electric Power and Energy
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• v.1 no.1
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• pp.175-180
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• 2015

A facile soft chemical synthesis route is used to grow nano-buds of copper hydroxide [$Cu(OH)_2$] thin films on stainless steel substrate[SS]. Besides different chemical methods for synthesis of $Cu(OH)_2$ nanostructure, the chemical bath deposition (CBD) is attractive for its simplicity and environment friendly condition. The structural, morphological, and electro-chemical properties of $Cu(OH)_2$ thin films are studied by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurement techniques. The results showed that, facile chemical synthesis route allows to form the polycrystalline, granular nano-buds of $Cu(OH)_2$ thin films. The electrochemical properties of $Cu(OH)_2$ thin films are studied in an aqueous 1 M KOH electrolyte using cyclic voltammetry. The sample exhibited supercapacitive behavior with $340Fg^{-1}$ specific capacitance. Moreover, electrochemical capacitive measurements of $Cu(OH)_2/SS$ electrode exhibit a high specific energy and power density about ${\sim}83Wh\;kg^{-1}$ and ${\sim}3.1kW\;kg^{-1}$, respectively, at $1mA\;cm^{-2}$ current density. The superior electrochemical properties of copper hydroxide ($Cu(OH)_2/SS$) electrode with nano-buds like structure mutually improves pseudocapacitive performance. This work evokes scalable chemical synthesis with the enhanced supercapacitive performance of $Cu(OH)_2/SS$ electrode in energy storage devices.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.62-70
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• 2015

Recently the demand for projected capacitance touch screens is sharply growing especially for large screens for medical devices, PC monitors and TVs. Large touch screens in general need a controller of higher complexity. They usually have a larger number of driving and sensing lines, and hence it takes longer to scan one frame for touch detection leading to a low frame scan rate. In this paper, a novel touch screen control technique is presented, which scans each frame in two steps of simultaneous multi-channel driving. The first step is to drive all driving lines simultaneously and determine which sensing lines have any touch. The second step is to sequentially rescan only the touched sensing lines, and determine exact positions of the touches. This technique can substantially increase the frame scan rate. This technique has been implemented using an FPGA and an AFE board, and tested using a commercial 23-inch touch screen panel. Experimental results show that the proposed technique improves the frame scan rate by 8.4 times for the 23-inch touch screen panel over conventional methods.

• Geophysics and Geophysical Exploration
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• v.19 no.4
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• pp.212-219
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• 2016

The development of more advanced geophysical exploration techniques is necessary because the orebodies as yet discovered are increasingly changing in characteristics from shallow/high-grade to deep/low-grade. In this work, laboratory measurement of physical properties of rock samples and a field survey and interpretation of spectral induced polarization (SIP) have been conducted in a skarn metallic deposit, Gagok mine. The purpose of this study is that the applicability of SIP in the exploration of skarn metallic deposits is verified by the comprehensive interpretation between SIP characteristics of rocks obtained from the laboratory measurements and inverted survey results from the field data. In order to understand the SIP characteristics of each lithology, the data of eighty nine rock samples utilized in the previous studies were revaluated. The field survey was carried out using frequency of 0.25 Hz along a survey line designed for intersecting lithological boundaries and evaluating mineralized zones. The mineralized rocks were more conductive (low-resistivity) and capacitive (high-chargeability or strong-phase) than other rocks. Thus, SIP can be one of the very useful tools for the mineral exploration of the skarn deposits.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.81-86
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• 2019

Metal oxide/graphene composites have been known as promising functional materials for advanced applications such as high sensitivity gas sensor, and high capacitive secondary battery. In this study, tin dioxide ($SnO_2$) nanostructures were grown on chemically synthesized graphene nanosheets using a two-zone horizontal furnace system. The large area graphene nanosheets were synthesized on Cu foil by thermal chemical vapor deposition system with the methane and hydrogen gas. Chemically synthesized graphene nanosheets were transferred on cleaned $SiO_2$(300 nm)/Si substrate using the PMMA. The $SnO_2$ nanostuctures were grown on graphene nanosheets at $424^{\circ}C$ under 3.1 Torr for 3 hours. Raman spectroscopy was used to estimate the quality of as-synthesized graphene nanosheets and to confirm the phase of as-grown $SnO_2$ nanostructures. The surface morphology of as-grown $SnO_2$ nanostructures on graphene nanosheets was characterized by field-emission scanning electron microscopy (FE-SEM). As the results, the synthesized graphene nanosheets are bi-layers graphene nanosheets, and as-grown tin oxide nanostructures exhibit tin dioxide phase. The morphology of $SnO_2$ nanostructures on graphene nanosheets exhibits complex nanostructures, whereas the surface morphology of $SnO_2$ nanostructures on $SiO_2$(300 nm)/Si substrate exhibits simply nano-dots. The complex nanostructures of $SnO_2$ on graphene nanosheets are attributed to functional groups on graphene surface.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1584-1588
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• 2018

During hyperthermia therapy, cancer cells are heated to a temperature in the range of $40{\sim}45^{\circ}C$ for a defined time period to damage these cells while keeping healthy tissues at safe temperatures. Prior to hyperthermia therapy, the amount of heat energy transferred to the cancer cells must be predicted. Among various non-invasive methods, the thermal prediction method using the specific absorption rate (SAR) is the most widely used method. The existing methods predict the thermal distribution by using a single constant for the mass density in one organ through assignment. However, because the SAR and the bio heat equation (BHE) vary with the mass density, the mass density of each organ must be accurately considered. In this study, the mass density distribution was calculated using the relationship between the Hounsfield unit and the mass density of tissues in preceding research. The SAR distribution was found using a quasi-static approximation to Maxwell's equation and was used to calculate the potential distribution and the energy distributions for capacitive RF heating. The thermal distribution during exposure to RF waves was determined by solving the BHE with consideration given to the considering contributions of heat conduction and external heating. Compared with reference data for the mass density, our results was within 1%. When the reconstructed temperature distribution was compared to the measured temperature distribution, the difference was within 3%. In this study, the density distribution and the thermal distribution were reconstructed for the agar phantom. Based on these data, we developed an algorithm that could be applied to patients.

• Smart Media Journal
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• v.9 no.4
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• pp.102-108
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• 2020

In this paper, we propose a real-time method of detecting hand motions and extracting the signal frame induced by EF(Electric Field) sensors. The signal induced by hand motion includes not only noises caused by various environmental sources as well as sensor's physical placement, but also different initial off-set conditions. Thus, it has been considered as a challenging problem to detect the motion signal and extract the motion frame automatically in real-time. In this study, we remove the PLN(Power Line Noise) using LPF with 10Hz cut-off and successively apply MA(Moving Average) filter to obtain clean and smooth input motion signals. To sense a hand motion, we use two thresholds(positive and negative thresholds) with offset value to detect a starting as well as an ending moment of the motion. Using this approach, we can achieve the correct motion detection rate over 98%. Once the final motion frame is determined, the motion signals are normalized to be used in next process of classification or recognition stage such as LSTN deep neural networks. Our experiment and analysis show that our proposed methods produce better than 98% performance in correct motion detection rate as well as in frame-matching rate.