• IEIE Transactions on Smart Processing and Computing
• /
• 제4권1호
• /
• pp.16-21
• /
• 2015

Most video services are transmitted in wireless networks. In a network environment, a packet of video is likely to be lost during transmission. For this reason, numerous error concealment (EC) algorithms have been proposed to combat channel errors. On the other hand, most existing algorithms cannot conceal the whole missing frame effectively. To resolve this problem, this paper proposes a new Adaptive Prediction Unit-based Motion Vector Extrapolation (APMVE) algorithm to restore the entire missing frame encoded by High Efficiency Video Coding (HEVC). In each missing HEVC frame, it uses the prediction unit (PU) information of the previous frame to adaptively decide the size of a basic unit for error concealment and to provide a more accurate estimation for the motion vector in that basic unit than can be achieved by any other conventional method. The simulation results showed that it is highly effective and significantly outperforms other existing frame recovery methods in terms of both objective and subjective quality.

• Nuclear Engineering and Technology
• /
• 제55권1호
• /
• pp.37-44
• /
• 2023

Using the Kalman filtering technique, we propose a novel method for estimating the missing video frames to monitor the activities inside the control room of a nuclear power plant (NPP). The purpose of this study is to reinforce the existing security and safety procedures in the control room of an NPP. The NPP control room serves as the nervous system of the plant, with instrumentation and control systems used to monitor and control critical plant parameters. Because the safety and security of the NPP control room are critical, it must be monitored closely by security cameras in order to assess and reduce the onset of any incidents and accidents that could adversely impact the safety of the NPP. However, for a variety of technical and administrative reasons, continuous monitoring may be interrupted. Because of the interruption, one or more frames of the video may be distorted or missing, making it difficult to identify the activity during this time period. This could endanger overall safety. The demonstrated Kalman filter model estimates the value of the missing frame pixel-by-pixel using information from the frame that occurred in the video sequence before it and the frame that will occur in the video sequence after it. The results of the experiment provide evidence of the effectiveness of the algorithm.

• Wind and Structures
• /
• 제13권3호
• /
• pp.221-234
• /
• 2010

In light-frame wood construction, missing roof-sheathing fasteners can be a relatively common occurrence. This type of construction makes up the vast majority of the residential building stock in North America and thus their performance in high winds, including hurricanes, is of concern due to their sheer number. Construction quality issues are common in these types of structures primarily because the majority are conventionally constructed and unlike steel and reinforced concrete structures, inspection is minimal except in certain areas of the country. The concept of performance-based wind engineering (PBWE), a relatively new paradigm, relies on the assumption that building performance under wind loads can be accurately modeled. However, the discrepancy between what is designed (and modeled) and what is built (the as-built) may make application of PBWE to light-frame wood buildings quite difficult. It can be concluded from this study that construction quality must be controlled for realistic application of PBWE to light-frame wood buildings.

• Nuclear Engineering and Technology
• /
• 제54권4호
• /
• pp.1153-1160
• /
• 2022

The application of video processing techniques are useful for the safety of nuclear power plants by tracking the people online on video to estimate the dose received by staff during work in nuclear plants. Nuclear reactors remotely visually controlled to evaluate the plant's condition using video processing techniques. Internal reactor components should be frequently inspected but in current scenario however involves human technicians, who review inspection videos and identify the costly, time-consuming and subjective cracks on metallic surfaces of underwater components. In case, if any frame of the inspection video degraded/corrupted/missed due to noise or any other factor, then it may cause serious safety issue. The problem of missing/degraded/corrupted video frame estimation is a challenging problem till date. In this paper a systematic literature review on video processing techniques is carried out, to perform their suitability analysis for NPP applications. The limitation of existing approaches are also identified along with a roadmap to overcome these limitations.

• 한국통신학회논문지
• /
• 제30권9C호
• /
• pp.877-886
• /
• 2005

Various frame recovery algorithms have been suggested to overcome the communication quality degradation problem due to Internet-typical impairments on Voice over IP(VoIP) communications. In this paper, we propose a new receiver-based recovery method which is able to enhance recovered speech quality with almost free computational cost and without an additional increment of delay and bandwidth consumption. Most conventional recovery algorithms try to recover the lost or erroneous speech frames by reconstructing missing coefficients or speech signal during speech decoding process. Thus they eventually need to modify the decoder software. The proposed frame recovery algorithm tries to reconstruct the missing frame itself, and does not require the computational burden of modifying the decoder. In the proposed scheme, the Vector Quantization(VQ) codebook indices of the erased frame are directly estimated by referring the pre-computed VQ Codebook Index Interpolation Tables(VCIIT) using the VQ indices from the adjacent(previous and next) frames. We applied the proposed scheme to the ITU-T G.723.1 speech coder and found that it improved reconstructed speech quality and outperforms conventional G.723.1 loss recovery algorithm. Moreover, the suggested simple scheme can be easily applicable to practical VoIP systems because it requires a very small amount of additional computational cost and memory space.

• Smart Structures and Systems
• /
• 제21권4호
• /
• pp.521-535
• /
• 2018

The main purpose of this paper is to predict missing absolute out-of-plane displacements and failure limits of infill walls by artificial neural network (ANN) models. For this purpose, two shake table experiments are performed. These experiments are conducted on a 1:1 scale one-bay one-story reinforced concrete frame (RCF) with an infill wall. One of the experimental models is composed of unreinforced brick model (URB) enclosures with an RCF and other is composed of an infill wall with bed joint reinforcement (BJR) enclosures with an RCF. An artificial earthquake load is applied with four acceleration levels to the URB model and with five acceleration levels to the BJR model. After a certain acceleration level, the accelerometers are detached from the wall to prevent damage to them. The removal of these instruments results in missing data. The missing absolute maximum out-of-plane displacements are predicted with ANN models. Failure of the infill wall in the out-of-plane direction is also predicted at the 0.79 g acceleration level. An accuracy of 99% is obtained for the available data. In addition, a benchmark analysis with multiple regression is performed. This study validates that the ANN-based procedure estimates missing experimental data more accurately than multiple regression models.

• 한국시뮬레이션학회논문지
• /
• 제23권4호
• /
• pp.65-74
• /
• 2014

IEEE 802.11n 표준은 네트워크 성능을 향상시키기 위해 MAC과 물리 계층에서 새로운 방법들을 제안하였다. MAC 계층에서 성능 향상을 위해 제안된 주요 방법은 프레임 집적(Frame Aggregation)과 Block ACK이다. IEEE 802.11n 표준에도 여전히 문제점은 존재한다. Block ACK 요청 프레임이나 Block ACK 응답 프레임이 손실되거나 에러가 포함되어 수신되면, 전송 단말은 집적된 큰 프레임에 포함된 작은 프레임들의 성공적인 전송 여부를 알지 못하기 때문에 모든 작은 프레임을 재전송한다. 이는 성공적으로 전송된 프레임도 재전송될 수 있기 때문에 네트워크의 성능 저하를 초래할 수 있다. 이 문제를 해결하기 위해 본 논문에서는 RRM(Reduced Retransmissions of MPDUs) 방법을 제안한다. 제안된 방법에서 송신 단말이 Block ACK 응답을 못 받으면 모든 프레임을 재전송하는 대신에 다음 데이터 프레임 하나를 전송하고 다시 Block ACK를 요청한다. 응답을 받은 후에 에러가 발생한 프레임에 대해서만 재전송을 수행한다. 제안된 방법의 성능을 시뮬레이션을 통해 분석한다. 시뮬레이션 결과, 제안된 방법이 다양한 패킷 에러 환경에서 효과적이고 네트워크 성능을 향상 시키는 것을 보여주었다.

• 대한음성학회지:말소리
• /
• 제43호
• /
• pp.101-112
• /
• 2002

In real time packetized voice application, missing packets are major source of voice quality degradation. Thus packet loss concealment (PLC) algorithms are needed to guarantee QoS of VoIP. In this paper, we describe packet loss concealment scheme utilizing the next good frame which follows loss packets. When this scheme is combined with other PLC algorithms, such as G.711 pitch waveform replication recommended by ITU-T LP based PLC algorithm, additional voice quality improvement is obtained for consecutive packet loss larger than 60 msec.

• Journal of Biosystems Engineering
• /
• 제26권3호
• /
• pp.253-262
• /
• 2001

This study was conducted to develop the vision system of a robotic transplanter for plug-seedling. A color image processing algorithm was developed to identify and locate empty cells and bad plants in the seedling tray. The image of pepper and tomato seedling tray was segmented into regions of plants, frame and soil using threshold technique which utilized Q of YIQ for finding leaves and H of HSI for finding frame of tray in the color coordinate system. The recognition system was able to successfully identify empty cells and bad seeding and locate their two-dimensional locations. The overall success rate of the recognition system was about 99%.

• 한국통신학회논문지
• /
• 제34권7C호
• /
• pp.687-696
• /
• 2009

동영상 신호의 프레임율 증가를 위해서 움직임 보상 보간(motion compensated interpolation) 기법이 많이 사용 된다. 특히 쌍방향 예측을 이용한 움직임 추정 기법은 움직임 추정 과정에서 빈 공간이나 겹쳐지는 문제를 해결함으로써 중간 삽입 프레임 생성 과정에서 좋은 성능을 보인다. 그러나 이와 같은 움직임 추정 과정에서 잘못된 움직임 벡터를 선택할 경우 왜곡된 블록을 생성할 수 있다. 본 논문에서는 쌍방향 움직임 예측을 기반으혹 하는 움직임 보상 보간 기법의 움직임 추정 과정에서 선택되는 움직임 벡터가 올바른 추정인지를 판별하고 인접한 움직임 벡터와 병함한 블록을 이용하여 1/2 화소 단위로 움직임 벡터를 보정하는 새로운 기법을 제안한다. 또한, 제안하는 기법이 기존의 움직임 벡터 추정 기법에 비해서 우수한 성능을 보이는 것을 모의 실험을 통하여 확인한다.