• Proceedings of the KSEG Conference
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• 2001.03a
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• pp.127-140
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• 2001

최근 지질공학의 다양한 분야에 영상처리기법들이 적용되고 있다. 그러나 영상의 획득 및 분석 단계에서 발생하는 각종 오차에 관한 문제는 많은 부분 무시되어 왔다. 이에 본 연구에서는 암석영상처리의 신뢰도 향상을 위한 컬러보정기법을 개발하였다. 표준 컬러차트를 이용하여 컬러보정과 오차분석을 수행하였으며, 그 결과 영상처리의 신뢰도 향상과 영상들간의 상호 비교·분석을 꾀할 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1122-1128
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• 2007

The denoising for image restoration based on the Wavelet Packet Transform with AA(Absolute Average) making-threshold is presented. The wavelet packet transform leads to be better in the part of high frequency than wavelet transform to eliminate noise. And the existing threshold determination is used standard deviation estimated results in increasing the noise and threshold, and damaging an image quality. In addition that is decreased image restoration PSNR by using the same threshold in spite of changing image because of installing a threshold in proportion of noise size. In contrast the AA thresholding method with wavelet packet is adapted by changing image to set up threshold by statistic quantity of resolved image and is avoided an extreme impact. The results on the experiment has improved 10% and 5% over than the denoising based on simple wavelet transform and wavelet packet respectively.

• Journal of Radiation Protection and Research
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• v.37 no.2
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• pp.84-89
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• 2012

The purpose of this study was to compare radiation dose and image quality between low-dose (LDP) and standard-dose protocol (SDP). LDP (120 kVp, 30 mAs, 2-mm thickness) and SDP (120 kVp, 180 mAs, 1.2-mm thickness) images obtained from 61 subjects were retrospectively evaluated at level of carina bifurcation, using multi-detector CT (Brilliance 16, Philips Medical Systems). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated at ascending aorta and infraspinatus muscle, from CT number and back-ground noise. Radiation dose from two protocols measured at 5-point using acrylic-phantom, and CT number and noise measured at 4-point using water-phantom. All statistical analysis were performed using SPSS 19.0 program. LDP images showed significantly more noise and a significantly lower SNR and CNR than did SDP images at ascending aorta and infraspinatus muscle. Noise, SNR and CNR were significantly correlated with body mass index (p<0.001). Radiation dose, SNR and CNR from phantom were significant differences between two protocols. LDP showed a significant reduction of radiation dose with a significant change in SNR and CNR compared with SDP. Therefore, exposure dose on LDP in clinical applications needs resetting highly more considering image quality.

• Broadcasting and Media Magazine
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• v.14 no.2
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• pp.88-98
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• 2009

MPEG에서는 빠르게 급변하는 시장의 요구를 충족시키기 위해, 기존의 긴 시간이 요구되는 표준화 방식과 달리, 서로 다른 기존 규격들을 특정 응용 서비스의 목적에 맞도록 조합해 하나의 표준으로 규격화하여 'MPEG-A(MPEG-Applications: ISO/IEC 23000) 멀티미디어 응용 표준'이라는 명칭으로 표준화 활동을 활발히 진행하고 있다. 본 논문에서는 2007년 10월 중국 신천에서 개최된 제 82차 MPEG회의에서 작업 표준안(Working Draft)으로 채택되어, 2008년 10월 부산에서 개최된 86차 MPEG회의에서 최종 국제표준 초안 (final draft international standard) 으로 승인된 스테레오스코픽 비디오 응용 포맷(Stereoscopic Video Application Format) 기술을 소개하고자 한다. 스테레오스코픽 비디오 응용 포맷은 현재 시장에 등장하여 점차 수요가 증가하고 있는 스테레오스코픽 카메라, 디스플레이, 모바일 단말 등의 장치를 이용한 스테레오스코픽 영상의 획득과 출력 서비스를 위한 요구사항 및 저장규격을 정의한다. 이러한 기술을 활용하여 기존의 특정 장치에서만 획득 및 출력이 가능했던 폐쇄적 서비스에서 벗어나, 스테레오스코픽 콘텐츠의 저장 및 사용자간 교환, 방송, 리치미디어 서비스에서의 활용 등과 같이 3차원 입체영상 콘텐츠의 활용도를 높일 수 있을 것으로 기대된다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1995.06a
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• pp.159-163
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• 1995

국제 표준화 기구(ISO)에서는 약 680 Mbyte의 저장 용량을 갖는 CD에서 1시간 정도의 동영상과 오디오를 압축, 저장할 수 있는 MPEG-1 부호화 방식의 표준안을 1991년에 결정하였다. 이를 기반으로 HDTV와 같은 디지털 방송을 위한 다채널 구조의 MPEG-2 규격을 결정하였다. 그러나 미국의 HDTV 표준안을 결정하는 대연합(Grand Alliance)에서는 영상에서는 MPEG-2를 선정하고 오디오 부호화 방식의 표준안으로는 돌비의 AC-3 방식을 선정하였다. 그러나 국내 및 유럽 등의 미국을 제외한 국가에서는 MPEG 오디오 알고리듬을 그대로 사용할 예정으로 있다. 이에 디지털 방식의 HDTV에 적용된 오디오 압축 방식의 두가지 표준 알고리듬의 돌비의 AC-3와 국제 표준화 기구의 MPEG 알고리듬에 대해 비교해 보고 앞으로의 동향에 대해 설명하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.896-903
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• 2011

In this paper, a co-design method for JPEG2000 video compression system using DSP and FPGA is presented. By profiling the complexity of JPEG2000 algorithm, it is noticed that a MQ-coder is the most complex part. Thus, we implement the MQ-coder on FPGA for the parallel processing using VHDL to reduce the complexity. In order to verify the performance of the MQ-coder, JBIG2 standard test vector and images are used. The experimental results show that the proposed MQ-coder enhances the processing time approximately 3 times compared with the previous software MQ-coder.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.253-255
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• 2010

Needs to study on distance measurement accuracy in aerial and satellite photogrammetry are rapidly increased. However, conventional studies show some confused definitions between measurement accuracy and measurement precision as well as standard deviation(STDEV) and root mean square error(RMSE or RMSD). So, Finite definitions of measurement accuracy and measurement precision as well as STDEV and RMSD are addressed in this paper. Experiment result show using correct definitions improve the distance measurement accuracy in aerial and satellite photogrammetry rapidly, but not the distance measurement accuracy in aerial and satellite photogrammetry.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.2
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• pp.90-94
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• 2013

Purpose: In the PET/CT images, various artifacts cause degradation of the quantitative assessment. Most hotspot generated by radiopharmaceutical injection errors cause an artifact and degrade the quality of the images as well as the accuracy of the quantitative evaluation. The purpose of this study is to assess effectiveness of the elimination of the hotspot at the injection sites using shifting the center of DFOV (Display Field of View, DFOV) method and evaluate the quantitative evaluation of result. Materials and Methods: GE Discovery STE 16 (GE Healthcare, Milwaukee, USA) and 1994 NEMA phantom were used for imaging acquisition. Phantom was filled with 0.005 MBq/mL of $^{18}F-FDG$. A hotspot was artificially placed on the outside of the phantom. The ratio of hotspot area activity to background area activity was regulated as 200:1. After image acquisition with routine protocol, all of the images were reconstructed using the shifting the center of DFOV method that wasn't overlapped with hotspot. Those images obtained before and after applying the shifting reconstruction method were compared. ROIs (Region Of Interests) were set in the hotspot areas, meanSUVs and standard deviations were calculated. Percentage differences were calculated with those meanSUVs and standard deviations. The evaluation on the effects of the shifting reconstruction method was done by comparison of the meanSUVs and the standard deviations, which were calculated for background areas unaffected by hotspot. Results: In the areas of unaffected by hotspot, meanSUVs before and after applying the shifting of center of DFOV method were $0.67{\pm}0.06g/mL$ and $0.65{\pm}0.06g/mL$, respectively. In the artifact areas affected by hotspot, meanSUVs before and after applying the shifting of center of DFOV method were $0.32{\pm}0.08g/mL$ and $0.56{\pm}0.12g/mL$, respectively. The percentage differences of the area adjacent to the hotspot and the area distant from the hotspot were 65.3% and 97.4%, respectively. Conclusion: In the PET/CT images, meanSUV was improved by 32.1% when the effect of artifact was removed with application of the shifting the center of DFOV methode. In other areas unaffected by artifacts, meanSUVs were not significantly different after applying DFOV center shift method. As shown in the result, adverse effects of hotspot made by swelling in the injection site can be reduced by applying DFOV center shift method. Therefore, DFOV center shift method can be applied for the more precise quantitative evaluation, and contribute to the increase of the diagnostic value of the images.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.4
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• pp.214-221
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• 2003

This paper shows an implementation of video codec (coder/decoder) on an embedded system. The video codec supports both H.261 and H.263 standards. For efficient real-time processing, the video codec is partitioned into a software module and a hardware module. Both modules are codesigned on an embedded system. The software module is processed on a real-time operating system and a RISC processor. It cooperates with the hardware module to compress and decompress images in real time. AMBA (Advanced Microcontroller Bus Architecture) AHB (Advanced High-performance Bus) is used as the system bus. The hardware module works both as AHB masters and as AHB slaves. The encoder part of the hardware module operates in a pipelines mode to compress images in real time. The video codec compresses 15 CIF frames and simultaneously decompresses 15 CIF frames in a second according to H.261 or H.263 standard at 33 MHz frequency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1039-1045
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• 2021

In modern society, due to the influence of the 4th industrial revolution, camera sensors and image-based automation systems are being used in various fields, and interest in image and signal processing is increasing. In this paper, we propose a digital filter algorithm for image reconstruction in an impulse noise environment. The proposed algorithm divides the image into eight masks in vertical, horizontal, and diagonal directions based on the local mask set in the image, and compares the standard deviation of each segmentation mask to obtain a reference value. The final output is calculated by applying the weight according to the spatial distance and the weight using the reference value to the local mask. To evaluate the performance of the proposed algorithm, it was simulated with the existing algorithm, and the performance was compared using enlarged images and PSNR.