• Journal of Korea Multimedia Society
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• v.24 no.4
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• pp.538-549
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• 2021

In this paper, we introduce a technique for 360-degree panoramic video streaming with multiple virtual cameras in real-time. The proposed technique consists of generating 360-degree panoramic video data by ORB feature point detection, texture transformation, panoramic video data compression, and RTSP-based video streaming transmission. Especially, the generating process of 360-degree panoramic video data and texture transformation are accelerated by CUDA for complex processing such as camera calibration, stitching, blending, encoding. Our experiment evaluated the frames per second (fps) of the transmitted 360-degree panoramic video. Experimental results verified that our technique takes at least 30fps at 4K output resolution, which indicates that it can both generates and transmits 360-degree panoramic video data in real time.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.7-9
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• 2021

본 논문은 Detectron2 [1]에서 지원하는 객체 검출 임무 수행 네트워크의 과정 중에서 추출한 피쳐 맵을 신경망 기반으로 압축하는 방법을 제안한다. 이를 위해, 신경 망 기반 영상 압축을 지원하는 공개 소프트웨어인 CompressAI [2] 모델 중 하나인 bmshj2018-hyperprior 의 압축 네트워크를 활용하여 임무 수행 네트워크의 과정 중 스탬 레이어(stem layer)에서 추출된 피쳐 맵을 압축하도록 학습시켰다. 또한, 압축 네트워크의 입력 피쳐 맵의 너비와 높이 크기가 64 의 배수가 되도록 객체 검출 네트워크의 입력 영상 보간 값을 조정하는 방법도 제안한다. 제안하는 신경망 기반 피쳐 맵 압축 방법은 피쳐 맵을 최근 표준이 완료된 차세대 압축 표준 방법인 VVC(Versatile Video Coding, [3])로 압축한 결과에 비해 큰 성능 향상을 보이고, VCM 앵커와 유사한 성능을 보인다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.36-38
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• 2021

본 논문은 물체 검출(Object Detection)과 물체영역분할(Object Segmentation)의 CNN 추론 결과를 MPEG-7 서술자 이진화를 통해 표현함으로써 원본과의 용량을 비교한다. 영상의 사용 목적에 따라 CNN 추론 결과를 압축하여 활용할 시 원본 영상 대비 용량을 측정하여 그 효율성을 판단하는 것이 목표이다. 물체 검출과 물체영역분할에 대한 추론 결과를 MPEG-7 서술자를 이용해 압축하였으며, 비교를 위해 원본 영상, CNN 추론 결과 파일, MPEG-7 서술자, MPEG-7 서술자 이진화 파일의 크기를 측정하였다. 실험 결과, MPEG-7 서술자를 이진화를 통한 표현 방식이 원본 영상 및 추론 결과 파일에 비해 효율적임을 알 수 있었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2021.06a
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• pp.157-160
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• 2021

프레임 단위 LiDAR (Light Detection And Ranging) 기반의 포인트 클라우드는 프레임 간 상관 관계가 높기 때문에 프레임 사이의 예측 기법을 사용하여 더 높은 압축 효율을 얻을 수 있으며, 이를 위해 MPEG의 G-PCC는 Inter-EM (Inter-Exploratory Model)의 표준화를 진행하고 있다. 특히, Inter-EM은 LiDAR 기반 포인트 클라우드의 이러한 특성을 효율적으로 압축하기 위해 전역 및 지역 움직임을 모두 고려하여 압축하는 구조로 설계되었다. 이 중 전역 움직임은 LiDAR 센서가 장착된 차량의 움직임으로 인해 발생되므로, 포인트 클라우드 내 모든 물체들이 동일한 움직임을 나타낼 것으로 예상된다. 하지만, LiDAR 기반 포인트 클라우드는 포인트 클라우드 내 점들의 특성에 따라서 전역 움직임이 나타나는 양상이 다르다. 본 논문은 이러한 LiDAR 기반 포인트 클라우드의 특성을 설명하고, LiDAR 기반 포인트 클라우드 압축 시 전역 움직임 압축을 위한 포인트 클라우드 분할 방안에 대해 제안한다. 본 논문에서 제안하는 포인트 클라우드 분할 방안을 활용한 전역 움직임 압축 시 기존 Inter-EM 대비 더 효율적인 압축이 가능하다.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.3
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• pp.35-41
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• 2002

There are many image segmentation methods having been published as the results of research so far, but it is difficult to be partitioned to each similar range that should be extracted into the accurate parameters of image information on the images with noises. Also if it is used to fractal coding, according to amount of noise in image, the image segmentation leads to decreasing of the compression ratio. In this paper, we propose the new quad-tree image segmentation using the box-counting dimension which can estimate the effective image information parameters against the noise properties and apply this method to fractal image coding. As the result of simulation, we confirm that the image segmentation is improved to 31.10% for parameter detection of image information and compression ratio is enhanced to 38.93% for fractal image coding when tested on 10% Gaussian white noise image by the proposed quad-tree method compared with method using existing quad-tree. 

• Journal of Korean Neurosurgical Society
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• v.37 no.6
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• pp.436-442
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• 2005

Objective: The detection rate of traumatic subdural hygroma(TSH) has increased after the development of computed tomography and magnetic resonance imaging. The treatment method and the mechanism of development of the TSH have been investigated, but they are still uncertain. This study is performed to evaluate the effectiveness of subduroperitoneal shunt in traumatic subdural hygroma. Methods: Five hundred thirty six patients were diagnosed as TSH from 1996 to 2002, among them, 55 patients were operated with subduroperitoneal shunt. We analyzed shunt effect on the basis of clinical indetails, including the patient's symptoms at the diagnosis, duration from diagnosis to operation, changes of GCS, hygroma types. We classified the TSH into five types (frontal, frontocoronal, coronal, parietal and cerebellar type) according to the location of the thickest portion of TSH. Results: The patients who have symptoms or signs related to frontal lobe compression (irritability, confusion) or increased intracranial pressure (headache, mental change), had symptomatic recovery rate above 80%. However, the patients who have focal neurological sign (hemiparesis, seizure and rigidity), showed recovery rate below 30%. The improvement rate was very low in the case of the slowly progressing TSH for over 6weeks. We experienced complications such as enlarged ventricle, chronic subdural hematoma, subdural empyema and acute SDH. Conclusion: Subduroperitoneal shunt appears to be effective in traumatic subdural hygroma when the patients who have symptoms or signs related to frontal lobe compression or increased ICP and progressing within 5weeks.

• Journal of IKEEE
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• v.22 no.3
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• pp.774-779
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• 2018

This paper presents fragile watermark system using quantization and DC coefficients. It is a way to prevent the watermark fro, being detected if the original has been modified in any way. In other words, the detection of a watermark ca be said to be originality after the watermark is inserted, without any damage. Since lossy compression such as JPEG is often allowed or required in practical applications, authentication methods, authentication methods should be distinguished from malicious modifications such as image shifting, cropping, filtering, and replacement. The proposed algorithm implements a fragile watermarking algorithm that shows image authentication with JPEC compression and the watermark easily breaks other malicious variants.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.999-1011
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• 2015

In modern electronic warfare, RADAR is under constant threat of ECM(Electronic Counter Measures) signals from nearby jammers. The conventional linear frequency modulated(Linear-FM) waveform is easy to be intercepted to estimate its signal parameters due to its periodical phase transition. Recently, APCN(Advanced Pulse Compression Noise) waveform using random amplitude and phase transition was proposed for LPI(Low probability of Intercept). But random phase code signals such as APCN waveform tend to be sensitive to Doppler frequency shift and result in performance degradation during moving target detection. In this paper, random phase and code rate transition based radar waveform(RPCR) is proposed for Doppler tolerance improvement. Time frequency analysis is carried out through ambiguity analysis to validate the improved Doppler tolerance of RPCR waveform. As a means to measure the vulnerability of the proposed RPCR waveform against LPI, WHT(Wigner-Hough Transform) is adopted to analyze and estimate signal parameters for ECCM(Electronic Counter Counter Measures) application.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.87-88
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• 2012

Because intra prediction modes in H.264 are determined by the brightness continuity between neighboring blocks, they can be used as a method for extracting edge information in the compression domain. However, if we just consider 9 intra prediction modes in H.264 as 9 different edge directions, we have the following two problems. First, intra prediction modes tend to yield too many edge blocks, generating unnecessary edge information. Second, we may not need all 9 directional edges (including the DC type) in H.264 intra prediction modes. For example, the EHD (edge histogram descriptor) in MPEG-7 defines only 4 directional edge types, namely horizontal, vertical, diagonal (HVD) edges with $0^{\circ}$, $90^{\circ}$, $45^{\circ}$, and $135^{\circ}$. Here, semi-diagonal (SD) edge types with $112.5^{\circ}$, $157.5^{\circ}$, $22.5^{\circ}$, and $67.5^{\circ}$ in the intra prediction modes in H.264 are not used. In this paper. we prepose a method that removes unnecessary edges from the intra prediction modes by utilizing the total average coefficient of 4x4 blocks in each slice and assign SD edges to HVD (horizontal, vertical, diagonal, $0^{\circ}$, $90^{\circ}$, $45^{\circ}$, $135^{\circ}$) edges by the contextual information of the neighboring blocks. Experimental results show that the edges determined by the proposed method in the compression domain are comparable to those of the previous edge detection methods in the spatial domain.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.237-244
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• 2009

The congestion in wireless sensor network increases the ratio of data loss and causes the delay of data. The existing congestion protocols for wireless sensor network reduces the amount of transmission by control the sampling frequency of the sensor nodes related to the congestion when the congestion has occurred and was detected. However, the control method of sampling frequency is not applicable on the situation which is sensitive to the temporal data loss. In the paper, we propose a new congestion control, ACT - Adaptive Congestion conTrol. The ACT monitors the network traffic with the queue usage and detects the congestion based on the multi level threshold of queue usage. Given network congestion, the ACT increases the efficiency of network by adaptive flow control method which adjusts the frequency of packet transmission and guarantees the fairness of packet transmission between nodes. Furthermore, ACT increases the quality of data by using the variable compression method. Through experiment, we show that ACT increases the network efficiency and guarantees the fairness to sensor nodes compared with existing method.