• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.2 s.314
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• pp.63-73
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• 2007

This paper proposes an illuminant-adaptive reproduction method using light adaptation and flare conditions for a mobile display. Displayed images in daylight are perceived as quite dark due to the light adaptation of the human visual system, as the luminance of a mobile display is considerably lower than that of an outdoor environment. In addition, flare phenomena decrease the color gamut of a mobile display and de-saturating the chroma. Therefore, this paper presents an enhancement method composed of lightness enhancement and chroma compensation. First, the ambient light intensity is measured using a lux-sensor, then the flare is calculated based on the reflection ratio of the display device and the ambient light intensity. To improve the perceived image, the image's luminance is transformed by linearization of the response to the input luminance according to the ambient light intensity. Next, the displayed image is compensated according to the physically reduced chroma, resulting from flare phenomena. This study presents a color reproduction method based on an inverse cone response curve and flare condition. Consequently, the proposed algorithm improves the quality of the perceived image adaptive to an outdoor environment.

• Journal of the Korean Society of Radiology
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• v.10 no.6
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• pp.443-450
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• 2016

In this study, we are using a computer tomography image of the abdomen, as an experimental linear research for the image of the fatty liver patients texture features analysis and computer-aided diagnosis system of implementation using the ROC curve analysis, from the computer tomography image. We tried to provide an objective and reliable diagnostic information of fatty liver to the doctor. Experiments are usually a fatty liver, via the wavelet transform of the abdominal computed tomography images are configured with the experimental image section, shows the results of statistical analysis on six parameters indicating a feature value of the texture. As a result, the entropy, average luminance, strain rate is shown a relatively high recognition rate of 90% or more, the control also, flatness, uniformity showed relatively low recognition rate of about 70%. ROC curve analysis of six parameters are all shown to 0.900 (p = 0.0001) or more, showed meaningful results in the recognition of the disease. Also, to determine the cut-off value for the prediction of disease six parameters. These results are applicable from future abdominal computed tomography images as a preliminary diagnostic article of diseases automatic detection and eventual diagnosis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.734-737
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• 2008

This paper presents a new automatic TFT-LCD image quality optimization system. We also have developed new algorithms using 6-point programmable matching technique with reference gamma curve, and automatic power setting sequence. It optimizes automatically gamma adjustment and power setting registers in mobile TFT-LCD driver IC to reduce gamma correction error, adjusting time, and flicker. Developed algorithms and programs are generally applicable for most of the TFT-LCD modules. The proposed optimization system contains module-under-test (MUT, TFT-LCD module), control program, multimedia display tester for measuring luminance and flicker, and control board for interface between PC and TFT-LCD module. The control board is designed with DSP, and it supports various interfaces such as RGB and CPU. Developed automatic image quality optimization system showed significantly reduced gamma adjusting time, reduced flicker, and much less average gamma error than competing system. We believe that the proposed system is very useful to provide high image quality TFT-LCD and to reduce developing process time using optimized gamma-curve setting and automatic power setting.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1617-1620
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• 2008

The effects of the temporal and permanent bright image stickings were examined under variable panel working gas pressure in the 42-in. ac-PDP with a high Xe (11 %) content. In the cells with and without temporal and permanent bright image stickings, the display luminance, firing voltage, and Vt closed curve were measured relative to the working gas pressure. With a decrease in the working gas pressure, the temporal bright image sticking was observed to be reduced, whereas the permanent bright image sticking was observed to be deteriorated.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.51 no.5
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• pp.203-211
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• 2002

In this paper, the implementation of a new AF(Automatic Focusing) system for a digital still camera is introduced. The proposed system operates in real-time while adjusting focus after the measurement of distance to an object using a passive sensor, which is different from a typical method. In audition, measurement errors were minimized by using the data acquired empirically, and the optimal measuring time was obtained using EV(Exposure Value) which is calculated from CCD luminance signal. Moreover, this system adopted an auxiliary light source for focusing in absolute dark conditions, which is very hard for CCD image Processing. Since this is an open-loop system adjusting focus immediately after the distance measurement, it guarantees real-time operation. The performance of this new AF system was verified by comparing the focusing value curve obtained from AF experiment with the one from the measurement by MF(Manual-Focusing). In both case, edge detector was used for various objects and backgrounds.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.145-146
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• 2000

Primary emphasis was placed on the electrophoretic deposition of low voltage phosphor to indium-tin oxide-coated glass for the application of field emission display. The phosphor deposited by various parameters, such as deposition time and applied voltages was examined in detail. In addition, a comparison was made by analyzing luminance properties of the phosphor mixed with and without conducting $In_2O_3$ powder of less than 1um size. The measurement was performed as a function of $In_2O_3$ concentration from 3% to 15% by weight. The enhanced impact of indium powder mixing on the phosphor was clearly demonstrated by aging performance curve at 1000V excitation voltages with a current density of $1\;mA/cm^2$

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.47 no.1
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• pp.17-28
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• 2010

This paper presents a new automatic TFT-LCD image quality optimization system using DSP for the first time. Since conventional manual method depends on experiences of LCD module developers, it is highly labor-intensive and requires several correction steps providing large gamma correction error. The proposed system optimizes automatically gamma adjustment and power setting registers in mobile TFT-LCD driver IC to reduce gamma correction error, adjusting time, and flicker. It contains module-under-test (MUT, TFT-LCD module), PC installed with program, multimedia display tester for measuring luminance and flicker, and control board for interface between PC and TFT-LCD module. We have developed a new algorithm using 6-point programmable matching technique with reference gamma curve and applying automatic power setting sequence. Developed algorithm and program are generally applicable for most of the TFT-LCD modules. It is realized to calibrate gamma values of 1.8, 2.0, 2.2 and 3.0, and reduce flicker level. The control board is designed with DSP and FPGA, and it supports various interfaces such as RGB and CPU. Developed automatic image quality optimization system showed significantly reduced gamma adjusting time, reduced flicker, and much less average gamma error than conventional manual method. We believe that the proposed system is very useful to provide high-quality TFT-LCD and to improve developing process using optimized gamma-curve setting and automatic power setting.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.64-72
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• 2006

We demonstrated organic light-emitting devices (OLEDs) based on the organic thin-film materials such as tris-(8-hydroxyquinoline) aluminum $(Alq_3)$. The structure of OLEDs was vacuum deposited upon transparent and thin glass substrates pre-coated with a transparent, conducting indium tin oxide thin film. The luminance characteristics, current, capacitance, and dispersion factor for degraded OLEDs, which were made by various bias currents $(0.5mA\;{\leq}\;I_{Bias}\;{\leq}9mA)$, are studied. The current dependences of lifetime were divided at approximately 2mA, and they represented nearly linear behaviors but had different slopes in a logarithmic plot of lifetime versus bias current. With lighting OLEDs, the anomaly of capacitance, as shown in the CV curve, occurred because of two factors, polarization in the bulk of organic materials and the interface between the metal and organic layers. In decayed OLEDs that had lower bias currents of less than 2mA, it was found that the degradation of luminance was related to both the decrease of polarization and to the lowering of the injection barrier.

• Korean Journal of Materials Research
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• v.26 no.9
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• pp.504-511
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• 2016

To prepare $Mn^{4+}$-activated $K_2TiF_6$ phosphor, a precipitation method without using hydrofluoric acid (HF) was designed. In the synthetic reaction, to prevent the decomposition of $K_2MnF_6$, which is used as a source of $Mn^{4+}$ activator, $NH_5F_2$ solution was adopted in place of the HF solution. Single phase $K_2TiF_6$:$Mn^{4+}$ phosphors were successfully synthesized through the designed reaction at room temperature. To acquire high luminance of the phosphor, the reaction conditions such as the type and concentration of the reactants were optimized. Also, the optimum content of $Mn^{4+}$ activator was evaluator based on the emission intensity. Photoluminescence properties such as excitation and emission spectrum, decay curve, and temperature dependence of PL intensity were investigated. In order to examine the applicability of this material to a white LED, the electroluminescence property of a pc-WLED fabricated by combining the $K_2TiF_6$:$Mn^{4+}$ phosphor with a 450 nm blue-LED chip was measured.

• Progress in Medical Physics
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• v.25 no.1
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• pp.31-36
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• 2014

We aimed to evaluate the dosimetric characteristics of reproducibility, linearity and dose dependence of optical stimulated luminance dosimeter (OSLD) in the Co-60 Gamma-rays and to analyze with a precedent study in field of the diagnostic radiography and radiotherapy. The reproducibility was 0.76% of the coefficient of variation, the homogeneity was within 1.5% of the coefficient of variation and OSLD had supra-linear response more than 3 Gy. So the correlation between dose and count was fitted by quadratic function. The count depletion by repeated reading was 0.04% per reading regardless of the irradiated dose. And the half time of decay curve according to the irradiated dose was 0.68 min. with 1 Gy, 1.04 min. with 5 Gy, and 1.10 min. with 10 Gy, respectively. In case of annealing for 30 min, the removal rate was 88% with 1 Gy, 90% with 5 Gy, and 92% with 10 Gy, respectively and 99% in case of annealing time for 4 hour. It is feasible to use OSLDs for dose evaluation in Co-60 Gamma-rays when considering the uncertainty on the procedure according to the irradiated dose.