• Journal of Internet Computing and Services
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• v.19 no.1
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• pp.105-111
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• 2018

This paper presents the analysis of image quality with FHD(Full HD) resolution camera equipped DIC(Digital Image Correlation) platform for the measurement of the architectural structure's relative displacement. DIC platform was designed based on i.MX6 of Freescale. Displacement measurement based on DIC method, the error is affected by image quality factors as pixel number, brightness, contrast, and SNR[dB](Signal to Noise Ratio). The effect were analyzed. The displacement of ROI(Region Of Interest) area within the image was measured by sub-pixel units based on DIC method. The non-contact telemetry property of DIC method, it can be used to long distance non-contact measurement. The various displacement results was measured and analyzed with the image quality factor adjustment according to the distance(25m, 35m, 50m).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.329-334
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• 2014

This paper proposes the hardware architecture of high performance multi-mode 2D forward transform for HEVC which has same number of cycles for processing any type of four TUs and yield high throughput. In order to make the original image which has high pixel and high resolution into highly compressed image effectively, the transform technique of HEVC supports 4 kinds of pixel units, TUs and it finds the optimal mode after performs each transform computation. As the proposed transform engine uses the common computation operator which is produced by analyzing the relationship among transform matrix coefficients, it can process every 4 kinds of TU mode matrix operation with 35cycles equally. The proposed transform block was designed by Verilog HDL and synthesized by using TSMC 0.18um CMOS processing technology. From the results of logic synthesis, the maximum operating frequency was 400MHz and total gate count was 214k gates which has the throughput of 10-Gpels/cycle with the $4k(3840{\times}2160)@30fps$ image.

• Journal of IKEEE
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• v.17 no.4
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• pp.570-578
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• 2013

This paper proposed an $8{\times}8$ HEVC inverse core transform architecture reusing multipliers. In HEVC core transform, processing of lower size block is identical with even part of upper size block. So an $8{\times}8$ core transform architecture can process both $8{\times}8$ and $4{\times}4$ core transforms. However, when $8{\times}8$ core transform architecture is exploited, frame processing time doubles in $4{\times}4$ core transform, since $8{\times}8$ and $4{\times}4$ core transforms concurrently process 8 and 4 pixels, respectively. In this paper, a novel inverse core transform architecture is proposed based on multiplier reuse. It runs as an $8{\times}8$ inverse core transformer or two $4{\times}4$ inverse core transformer. Its frame processing time is same in $8{\times}8$ and $4{\times}4$ core transforms, and reduces gate counts by 12%.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.7
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• pp.53-60
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• 2009

Motion estimation for H.264/AVC video CODEC is very complex and requires a huge amount of computational efforts because it uses multiple reference frames and variable block sizes. We propose the architecture of high-performance integer-pixel motion estimation circuit based on fast algorithms for multiple reference frame selection, block matching, block mode decision and motion vector estimation. We also propose the architecture of high-performance interpolation circuit for sub-pixel motion estimation. We described the RTL circuit in Verilog HDL and synthesized the gate-level circuit using 130nm standard cell library. The integer-pixel motion estimation circuit consists of 77,600 logic gates and four $32\times8\times32$-bit dual-port SRAM's. It has tile maximum operating frequency of 161MHz and can process up to 51 D1 (720$\times$480) color in go frames per second. The fractional motion estimation circuit consists of 22,478 logic gates. It has the maximum operating frequency of 200MHz and can process up to 69 1080HD (1,920$\times$1,088) color image frames per second.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.12-18
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• 2008

Ag paste was employed for source and drain electrode of OTFTs and for the data metal lines of OTFT-OLED array on PC(polycarbonate) substrate. We tested two kinds of Ag-pastes such as pastes for 325 mesh and 500 mesh screen mask to examine the pattern ability and electrical performance for OTFTs. The minimum feature size was 60 ${\mu}m$ for 325 mesh screen mask and 40 ${\mu}m$ for 500 mesh screen mask. The conductivity was 60 $m{\Omega}/\square$ for 325 mesh and 133.1 $m{\Omega}/\square$ for 500 mesh. For the OTFT performance the mobility was 0.35 $cm^2/V{\cdot}sec$ and 0.12 $cm^2/V{\cdot}sec$, threshold voltage was -4.7 V and 0.9 V, respectively, and on/off current ratio was ${\sim}10^5$, for both screen masks. We applied the 500 mash Ag paste to OTFT-OLED array because of its good patterning property. The pixel was composed of two OTFTs and one capacitor and one OLED in the area of $2mm{\times}2mm$. The panel successfully worked in active mode operation even though there were a few bad pixels.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.53.2-53.2
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• 2010

지금까지 능동 구동 디스플레이의 TFT backplane에 사용하고 있는 채널 물질로는 수소화된 비정질 실리콘(a-Si:H)과 저온 폴리실리콘(low temperature poly-Si)이 대표적이다. 수소화된 비정질 실리콘은 TFT-LCD 제조에 주로 사용되는 물질로 제조 공정이 비교적 간단하고 안정적이며, 생산 비용이 낮고, 소자 간 특성이 균일하여 대면적 디스플레이 제조에 유리하다. 그러나 a-Si:H TFT의 이동도(mobility)가 1 cm2/Vs이하로 낮아 Full HD 이상의 대화면, 고해상도, 고속 동작을 요구하는 UD(ultra definition)급 디스플레이를 개발하는데 있어 한계 상황에 다다르고 있다. 또한 광 누설 전류(photo leakage current)의 발생을 억제하기 위해서 화소의 개구율(aperture ratio)을 감소시켜야하므로 패널의 투과율이 저하되고, 게이트 전극에 지속적으로 바이어스를 인가 시 TFT의 문턱전압(threshold voltage)이 열화되는 문제점을 가지고 있다. 문제점을 극복하기 위한 대안으로 근래 투명 산화물 반도체(transparent oxide semiconductor)가 많은 관심을 얻고 있다. 투명 산화물 반도체는 3 eV 이상의 높은 밴드갭(band-gap)을 가지고 있어 광 흡수도가 낮아 투명하고, 광 누설 전류의 영향이 작아 화소 설계시 유리하다. 최근 다양한 조성의 산화물 반도체들이 TFT 채널 층으로의 적용을 목적으로 활발하게 연구되고 있으며 ZnO, SnO2, In2O3, IGO(indium-gallium oxide), a-ZTO(amorphous zinc-tin-oxide), a-IZO (amorphous indium-zinc oxide), a-IGZO(amorphous indium-galliumzinc oxide) 등이 그 예이다. 이들은 상온 또는 $200^{\circ}C$ 이하의 낮은 온도에서 PLD(pulsed laser deposition)나 스퍼터링(sputtering)과 같은 물리적 기상 증착법(physical vapor deposition)으로 손쉽게 증착이 가능하다. 특히 이중에서도 a-IGZO는 비정질임에도 불구하고 이동도가 $10\;cm2/V{\cdot}s$ 정도로 a-Si:H에 비해 월등히 높은 이동도를 나타낸다. 이와 같이 a-IGZO는 비정질이 가지는 균일한 특성과 양호한 이동도로 인하여 대화면, 고속, 고화질의 평판 디스플레이용 TFT 제작에 적합하고, 뿐만 아니라 공정 온도가 낮은 장점으로 인해 플렉시블 디스플레이(flexible display)의 backplane 소재로서도 연구되고 있다. 본 실험에서는 rf sputtering을 이용하여 증착한 a-IGZO 박막에 대하여 열처리 조건 변화에 따른 a-IGZO 박막들의 광학적, 전기적 특성변화를 살펴보았고, 이와 더불어 a-IGZO 박막을 TFT에 적용하여 소자의 특성을 분석함으로써, 열처리에 따른 Transfer Curve에서의 우리가 요구하는 Threshold Voltage(Vth)의 변화를 관찰하였다.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.533-542
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• 2017

In diagnostic radiology, the imaging system has been changed from film/screen to digital system. However, the method for removing scatter radiation such as anti-scatter grid has not kept pace with this change. Therefore, authors have devised the indirect flat panel detector (FPD) system with net-like lead in substrate layer which can remove the scattered radiation. In clinical context, there are many radiographic examinations with angulated incident X-ray. However, our proposed FPD has net-like lead foil so the vertical lead foil to the angulate incident X-ray would have bad effect on its performance. In this study, we identified the effect of vertical/horizontal lead foil component on the novel system's performance and improved the structure of novel system for clinical usage with angulated incident X-ray. Grid exposure factor and image contrast were calculated to investigate various structure of novel system using Monte Carlo simulation software when the incident X-ray was tilted ($0^{\circ}$, $15^{\circ}$, and $30^{\circ}$ from the detector plane). More photons were needed to obtain same image quality in the novel system with vertical lead foil only then the system with horizontal lead foil only. An optimal structure of novel system having different heights of its vertical and horizontal lead foil component showed improved performance compared with the novel system in a previous study. Therefore, the novel system will be useful in a clinical context with the angulated incident X-ray if the height and direction of lead foil in the substrate layer are optimized as the condition of conventional radiography.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.513-524
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• 2022

Recently, detecting damages of civil infrastructures from digital images using deep learning technology became a very popular research topic. In order to adapt those methodologies to the field, it is essential to explain robustness of deep learning models. Our research points out that the existing pixel-based deep learning model evaluation metrics are not sufficient for detecting cracks since cracks have linear appearance, and proposes a new evaluation methodology to explain crack segmentation deep learning model more rationally. Specifically, we design, implement and validate a methodology to generate tolerance buffer alongside skeletonized ground truth data and prediction results to consider overall similarity of topology of the ground truth and the prediction rather than pixel-wise accuracy. We could overcome over-estimation or under-estimation problem of crack segmentation model evaluation through using our methodology, and we expect that our methodology can explain crack segmentation deep learning models better.

• Investigative Magnetic Resonance Imaging
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• v.6 no.1
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• pp.28-34
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• 2002

Purpose : The minimum stimulus onset asynchronoy(SOAmin) is one of important experimental parameters for an event-related fMRI experiment designed with the stochastic stimulus. In this study, the most efficient SOAmin is explored for the stronger activation in motor and language tasks with the stimulus designed stochastically. Materials and methods : The event-related fMRI during motor and language tasks were obtained in four normal right-handed subjects. EPI-BOLD sequence is used at 1.5Tesla MR system for the acquisition of event-related fMRI. For each task the subjects are responded for the stimulus' with 2, 3, 4, and 6 seconds SOAmin. The obtained images are processed with SPM99, and the p value is set as 0.05 for the significant activation detection. The Z value and the number of activated pixels are compared for each task. Results : For the motor task, the primary and supplementary motor areas are activated, and for the language task the consistent activated signals are detected in the Broca's. The activated signal is to be stronger for the shorter SOAmin for both motor and language tasks. At primary motor area, the activated signals is the strongest for 3 seconds SOAmin and for the supplementary motor area the result with 2 seconds SOAmin shows the strongest activation. And the result of language task shows the strongest activation at the 2 seconds SOAmin. Conclusion : In the event-related fMRI of motor and language tasks with the stochastically designed stimulus, the 2 or 3 seconds SOAmin is efficient for more activated and clustered activation.

• Korean Journal of Environment and Ecology
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• v.32 no.6
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• pp.686-697
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• 2018

Due to the advance in remote sensing technology, it has become easier to more frequently obtain high resolution imagery to detect delicate changes in an extensive area, particularly including forest which is not readily sub-classified. Time-series analysis on high resolution images requires to collect extensive amount of ground truth data. In this study, the potential of land coverage mapas ground truth data was tested in classifying high-resolution imagery. The study site was Wonju-si at Gangwon-do, South Korea, having a mix of urban and natural areas. KOMPSAT-3A imagery taken on March 2015 and land coverage map published in 2017 were used as source data. Two pixel-based classification algorithms, Support Vector Machine (SVM) and Random Forest (RF), were selected for the analysis. Forest only classification was compared with that of the whole study area except wetland. Confusion matrixes from the classification presented that overall accuracies for both the targets were higher in RF algorithm than in SVM. While the overall accuracy in the forest only analysis by RF algorithm was higher by 18.3% than SVM, in the case of the whole region analysis, the difference was relatively smaller by 5.5%. For the SVM algorithm, adding the Majority analysis process indicated a marginal improvement of about 1% than the normal SVM analysis. It was found that the RF algorithm was more effective to identify the broad-leaved forest within the forest, but for the other classes the SVM algorithm was more effective. As the two pixel-based classification algorithms were tested here, it is expected that future classification will improve the overall accuracy and the reliability by introducing a time-series analysis and an object-based algorithm. It is considered that this approach will contribute to improving a large-scale land planning by providing an effective land classification method on higher spatial and temporal scales.