• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.65-74
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• 2005

This Paper Propose a robust scene change detection technique that use the weighted chi-square test and the automated threshold-decision algorithm. The weighted chi-test can subdivide the difference values of individual color channels by calculating the color intensities according to mSC standard, and it can detect the scene change by joining the weighted color intensities to the predefined chi-test which emphasize the comparative color difference values. The automated decision algorithm uses the difference values of frame-to-frame that was obtained by the weighted chi-test. In the first step, The average of total difference value and standard deviation value is calculated and then, subtract the mean value from the each difference values. In the next step, the same process is performed on the remained difference value. The propose method is tested on various sources and in the experimental results, it is shown that the Proposed method is efficiently estimates the thresholds and reliably detects scene changes.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2419-2425
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• 2007

New poly(cyclopenta[def]phenanthrene) (PCPP)-based conjugated copolymers, containing carbazole units as pendants, were prepared as the electroluminescent (EL) layer in light-emitting diodes (LEDs) to show that most of them have higher maximum brightness and EL efficiency. The prepared polymers, Poly(2,6-(4-(6-(Ncarbazolyl)- hexyl)-4-octyl-4H-cyclopenta[def]phenanthrene)) (CzPCPP10) and Poly(2,6-(4-(6-(N-carbazolyl)- hexyl)-4-octyl-4H-cyclopenta[def]phenanthrene))-co-(2,6-(4,4-dioctyl-4H-cyclopenta[def]phenanthrene)) (CzPCPP7 and CzPCPP5), were soluble in common organic solvents and used as the EL layer in light-emitting diodes (LEDs) of configuration with ITO/PEDOT/polymer/Ca/Al device. The polymers are thermally stable with glass transition temperature (Tg) at 77-100 °C and decomposition temperature (Td) at 423-457 °C. The studies of cyclic voltammetry indicated same HOME levels in all polymers, although the ratios of carbazole units are different. In case of PLEDs with configuration of ITO/PEDOT/CzPCPPs/Ca/Al device, The EL maximum peaks were around 450 nm, which the turn-on voltages were about 6.0-6.5 V. The maximum luminescence of PLEDs using CzPCPP10 was over 4400 cd/m2 at 6.5 V, which all of the maximum EL efficiency were 0.12 cd/A. The CIE coordinates of the EL spectrum of PLEDs using CzPCPP10 was (0.18, 0.08), which are quite close to that of the standard blue (0.14, 0.08) of NTSC.

• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.122-126
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• 2010

In this article photoluminescence of the $Al_2O_3:xCr_2O_3$ solid solutions prepared by solid state reaction method are represented. The effect of $Cr_2O_3$-activator concentration and heat treatment time on the PL characteristics have been discussed in conjunction with microstructure of phosphor samples. The $Al_2O_3:xCr_2O_3$ phosphors show the highest PL intensity at x=0.003 mole when the samples are reacted at $1600^{\circ}C$ for 5 h. The PL emission and absorption spectra show the maximum peaks at 698 nm and at 398 nm respectively. The CIE color coordinate is (x=0.646, y=0.316) at 0.003 mole $Cr_2O_3$, which value is very close to the NTSC coordinate of red color. This characteristic feature of $Al_2O_3:xCr_2O_3$ has been applied for an additive to improve the color characteristic of other red phosphor $LiEuW_2O_8$ which has a relatively poor color purity with an emission peak centered at 615 nm and with a CIE coordinate (x=0.530, y=0.280). The $Al_2O_3:0.003Cr_2O_3$ phosphor has been mixed with the $LiEuW_2O_8$ phosphor powder and the PL characteristics and CIE color coordinates are characterized. The $Al_2O_3:xCr_2O_3$ phosphor was found effective for improving the CRI (color rendering index) of $LiEuW_2O_8$ phosphor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.38-46
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• 2011

In this paper, we propose a calculation methodology of the service distance to assure the satisfactory quality of service for analogue and digital TV receivers. Using the field strength formulation for TV receiver based upon Rec. ITU-R P.1546, computational results are presented and discussed for both systems, and some important factors are reviewed in terms of the equivalent level of service, which must be kept due to ATV to DTV conversion. The presented method provides the predicted values of field strength at receiver areas to check whether transmission quality can be satisfied or not, and it can be also used for obtaining the protection ratio or separated distance from co-channel or adjacent interference signal.

• The Journal of Korean Association of Computer Education
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• v.8 no.6
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• pp.103-111
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• 2005

This paper presents a novel automated threshold-decision algorithm that uses the mean and standard-deviation values obtained from the difference values of consecutive frames. At first, the calculation of difference values is obtained by the weighted ${\chi}^2$-test algorithm which was modified by joining color histogram to ${\chi}^2$-test algorithm. The weighted ${\chi}^2$-test algorithm can subdivide the difference values by imposing weights according to NTSC standard. In the first step, the proposed automatic threshold-decision algorithm calculates the mean and standard-deviation value from the total difference values, and then subtracts the mean value from the each difference values. In the next step, the same process is performed on the remained difference values, and lastly, the threshold is detected from the mean when the standard deviation has a maximum value. The proposed method is tested on various video sources and, in the experimental results, it is shown that the proposed method efficiently estimates the thresholds and reliably detects scene changes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.10
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• pp.66-74
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• 2008

Surveillance system using active tracking camera has no distance limitation of surveillance range compared to supersonic or sound sensors. However, complex motion tracking algorithm requires huge amount of computation. Compared to conventional methods using DSPs or embedded processors, this paper proposes and implements a novel motion tracker unit that detects and extracts motion information of moving objects by using picture difference of consecutive frames. The proposed motion tracker unit was implemented in FPGA with about 13,000 gates. It processes NTSC format video and was verified by embedding it into the active surveillance camera system. We also propose and implements a motion estimator unit linkable to video codec by embedding the proposed motion tracker unit into ready-made motion estimator unit. The implemented motion estimator unit is about 17,000 gates in $0.35{\mu}m$ process.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.600-607
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• 2008

Reliable wireless transmission of data generated by the flight critical subsystems or mission equipments of the unmanned aerial system is critical for mission success. As the UAS system becomes more sophisticated, its dependency on a reliable high rate radio communication system also increases. This requirement is applied not only during the operation phase but also in the early development test phase. This paper introduces a practical cost-effective communication system for a UAS. The downlink module combines analog NTSC video signal with onboard data, and send them using 2.4 GHz carrier wave. The uplink system has less a severe requirement on the bandwidth, and thus uses 430 MHz signal. This paper also presents a sample packet structure which can be adopted for many UAS of similar class.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.6 s.312
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• pp.83-91
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• 2006

Flashlights in video has many problem to detect the scene change because of high difference values from successive frames. In this paper propose the reliable scene change detection algorithms by extracting the flashlights. This paper proposes a robust scene change detection technique that uses the weighted chi-square test and the automated threshold-decision algorithms. The weighted chi-square test can subdivide the difference values of individual color channels by calculating the color intensities according to NTSC standard, and it can detect the scene change by joining the weighted color intensities to the predefined chi-square test which emphasize the comparative color difference values. The automated threshold-decision algorithm uses the difference values of frame-to-frame that was obtained by the weighted chi-square test. At first, The Average of total difference values is calculated and then, another average value is calculated using the previous average value from the difference values, finally the most appropriate mid-average value is searched and considered the threshold value. Experimental results show that the proposed algorithms are effective and outperform the previous approaches.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.469-476
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• 1998

In the case of acquisition and displaying medical Images such as ultrasonography and endoscopy on VGA monitor of PC system, image degradation of tear-drop appears through scan conversion. In this study, we compare several methods which can solve this degradation and implement the hardware system that resolves this problem in real-time with PC. It is possible to represent high quality image display and real-time processing and acquisition with specific de-interlacing device and PCI bridge on our hardware system. Image quality is improved remarkably on our hardware system. It is implemented as PC-based system, so acquiring, saving images and describing text comment on those images and PACS networking can be easily implemented.metabolism. All images were spatially normalized to MNI standard PET template and smoothed with 16mm FWHM Gaussian kernel using SPM96. Mean count in cerebral region was normalized. The VOls for 34 cerebral regions were previously defined on the standard template and 17 different counts of mirrored regions to hemispheric midline were extracted from spatially normalized images. A three-layer feed-forward error back-propagation neural network classifier with 7 input nodes and 3 output nodes was used. The network was trained to interpret metabolic patterns and produce identical diagnoses with those of expert viewers. The performance of the neural network was optimized by testing with 5~40 nodes in hidden layer. Randomly selected 40 images from each group were used to train the network and the remainders were used to test the learned network. The optimized neural network gave a maximum agreement rate of 80.3% with expert viewers. It used 20 hidden nodes and was trained for 1508 epochs. Also, neural network gave agreement rates of 75~80% with 10 or 30 nodes in hidden layer. We conclude that artificial neural network performed as well as human experts and could be potentially useful as clinical decision support tool for the localization of epileptogenic zones.

• Information Display
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• v.23 no.4
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• pp.12-21
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• 2022

반도체 기반 양자점 (QD)소재와 CsPbX3 (X=Cl, Br, I)기반 perovskite 양자점 또는 나노결정 소재(PNC)는 매우 우수한 양자효율과 좁은 발광 선폭으로 고색재현성 디스플레이 색변환 소재 또는 발광 소재로서 각광을 받고 있다. 그러나, 기존 화학적 합성법을 통해 제조되는 QD 및 PNC 소재는 취약한 열 및 화학적 안정성으로 인해 장기 내구성의 개선이 요구된다. 이들 QD 및 PNC 소재는 모두 완전 무기 소재인 산화물 기반 유리 소재내에 생성이 가능하며, 이를 통해 장기 내구성을 근본적으로 개선할 수 있다. 반도체 기반 QD 함유 유리소재 (QDEG)의 경우, 유리 내 core/shell 구조를 가진 QD의 생성으로 양자효율의 향상이 가능했으나, 콜로이드 기반 양자점 (cQD)과 달리 다중 shell의 형성이 어려워 양자효율이 제한되고, 발광 선폭이 넓어 고색재현성 디스플레이용 색변환 소재로 적용되기에는 아직 한계가 있다. 한편, Perovskite 양자점 (또는 나노결정) 함유 유리소재 (PNEG) 소재는 QDEG과 달리 콜로이드 기반의 PNC (c-PNC)가 가지는 우수한 양자효율과 20 nm 수준의 좁은 선폭을 유리 내에서도 가지며, c-PNC 대비 열적, 화학적 및 광학적 안정성이 획기적으로 향상되어 실질적인 응용 가능성을 높이고 있다. 특히, 일반적인 용융-급랭법으로 제조하여 대량생산에 용이하고, 분말 또는 판상 등 다양한 형태로의 제작이 가능한 장점이 있다. 현재까지 제조된 PNEG의 최대 PL-QY는 450 nm 여기 시 녹색 및 적색에서 약 60% 수준이며, Al₂O₃ 분말을 이용할 경우 최대 80% 수준까지 달성이 가능하다. 또한, PNEG과 blue LED를 이용하여 백색 LED를 구현할 경우 color filter를 적용하지 않을 때, NTSC 대비 최대 약 130 % 수준의 높은 색재현 영역을 보여 주고 있으며, 실제 LCD용 BLU로 적용 시 기존 상용 c-QD 소재와 동등 이상의 색재현 영역을 보이고 있어, 실질적인 응용 가능성이 매우 높음을 확인하였다. PNEG의 상업적인 응용을 위해서는 몇 가지 추가적인 연구 개발이 필요하다. 기존 c-QD 또는 c-PNC는 나노 수준 크기의 입자가 액상에 분산된 형태로 입도 제어가 용이하나, PNEG의 경우 분말 제조 시 유리 형성 후 분쇄를 통해 제조되며, 입도가 대개 수십 ㎛ 이하로 작아질 경우 PL-QY가 저하되어, 향후 잉크젯 공정 응용을 위해서는 고효율의 분말 제조공정 개발이 필요하다. 또한, 유리 소재의 경우 절연체로서 기존 QD 소재 대비 electro-luminescence(EL) 소자의 활성층으로 사용하는데 제약이 있어 PNEG을 이용한 EL 소자 제작에 대한 연구도 필요하다. 마지막으로, 기존 c-PNC 소재와 같이 Pb가 함유되지 않은 PNEG 소재의 개발이 선결되어야 할 것으로 판단된다. 이와 같은 해결 과제들에도 불구하고, PNEG 소재는 기존 c-QD 소재 대비 매우 우수한 안정성을 기반으로 고품위 고색재현 디스플레이용 색변환 소재로서 다양한 응용에 활용될 수 있을 것으로 기대된다.