• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2C
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• pp.201-208
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• 2003

The error concealment is very useful technique for real-time communication, such as video conference. In this paper. we propose the error concealment technique to minimize discontinuity of block boundary in consideration of the fact that human visual system is sensitive to discontinuity. The error concealment for each loss block is performed by extended block matching method based on gradient difference. In the simulation result, performance improvement for the proposed technique is on the average 1.32㏈ in comparison with the conventional technique.

• ETRI Journal
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• v.28 no.5
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• pp.574-582
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• 2006

In this paper, a new error concealment algorithm is proposed for the H.264 standard. The algorithm consists of two processes. The first process uses a fuzzy logic method to select the size type of lost blocks. The motion vector of a lost block is calculated from the current frame, if the motion vectors of the neighboring blocks surrounding the lost block are discontinuous. Otherwise, the size type of the lost block can be determined from the preceding frame. The second process is an error concealment algorithm via a proposed adapted multiple-reference-frames selection for finding the lost motion vector. The adapted multiple-reference-frames selection is based on the motion estimation analysis of H.264 coding so that the number of searched frames can be reduced. Therefore the most accurate mode of the lost block can be determined with much less computation time in the selection of the lost motion vector. Experimental results show that the proposed algorithm achieves from 0.5 to 4.52 dB improvement when compared to the method in VM 9.0.

• The KIPS Transactions:PartB
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• v.11B no.6
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• pp.661-666
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• 2004

In the wireless communication systems, transmission errors degrade the reconstructed image quality severely. Error concealment in video communication is becoming increasingly important because transmission errors can cause single or multiple loss of macroblocks in video delivery over unreliable channels such as wireless networks and internet. Among various techniques which can reduce the degradation of video quality, the error concealment techniques yield good performance without overheads and the modification of the encoder. In this paper, lost image blocks can be concealed with the OBMC(Overlapped Block Motion Compensation) after new motion vectors of the lost image blocks are allocated by median values using the adaptive selection with motion vectors of adjacent blocks. We know our algorithm is more effective in case of continuous GOB loss. The results show a significant improvement over the zero motion error concealment and other temporal concealment methods such as Motion Vector Rational Interpolation or Median＋OBMC by 3dB gain in PSNR.

• Journal of the Korea Safety Management & Science
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• v.10 no.3
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• pp.29-33
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• 2008

According to statistics released by the Ministry of Labor for the past 6 years, work-related accidents in the construction industry have been on the continued increase, resulting in social and economic losses that are difficult to determine at an exact amount. However, the number will likely get much bigger if unreported cases are included, considering the fact that the aforementioned statistics are based soley on the applications filed with Korea Workers' Compensation and Welfare Service. The practice of businesses choosing not to report and dealing with industrial accidents in an unauthorized manner is defined as "concealment of industrial accident". The reason the employers tend to engage in the concealment practice even at their huge cost is a "pre-qualification" scheme for the applicants in the government procurement process. Under the pre-qualification scheme, the applicants with a high rate of industrial accidents receive a low grade and become less attractive candidates in the procurement process, thus losing an opportunity to win a contract. Such failure relates directly to the fate of business organizations, to survive or not. That is why they are making all-out efforts to obtain a high grade in the pre-qualification evaluation. With regard to the accident-concealment problem, the following can be mentioned as preventive measures: (1) To exclude a rate of industrial accidents from the pre-qualification scheme; (2) To strengthen the institution of imposing penalties on the occurrence of industrial accidents; (3) To introduce private insurance system to the current industrial accident compensation insurance; and (4) To give non-recognition treatment to industrial accidents that were not reported upon occurrence. In conclusion, the concealment problem can be resolved if the aforementioned measures are to be taken continuously along with corrective measures against institutional deficiencies.

• Journal of Acupuncture Research
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• v.24 no.1
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• pp.127-135
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• 2007

Objectives: To evaluate the methodological quality of Korean Acupuncture Clinical trials Methods : Two independent researchers reviewed 12 protocols of Acupuncture clinical trials which were conducted in Korea 2006. Also, Survey Principal Investigator of those was conducted. We compare the results of protocol review with investigator reponses of actual practice. Quality assessment consisted of 5 items including random sequence generation, randomization method, allocation concealment, subject blinding, assessor blinding. Results : Randomization was performed using the proper procedure to insure that treatment assignment is unbiased and concealed from subjects in all clinical trials, According to protocols, 6(50%) of 12 clinical trials used computer-generated random numbers, 6(50%) remaining trials didn't describe the randomization method. Also all trials used appropriate randomization methods on the basis of the survey results: 8 trials used computer-generated random number, 2 used random table. Of 7 protocols in which allocation concealment was stated, 5(71%) reported appropriate method (Calling a central office or statisticians, Sealed opaque envelopes). However according to survey, 5(42%) of 12 trials used inappropriate allocation concealment (Keeping a master randomization list and referring to when subject entered the trial). In addition, the result of protocol review and survey response was not coincident in 5(42%) trials. Subject blinding was conducted in all except 1 clinical trials. Although 11(92%) of 12 trials were conducted using assessor blinding in actual practice, only 7(58%) reported that in protocol. Conclusion : Although randomization and blinding were conducted adequately, allocation concealment was used inadequately, Not only appropriate allocation concealment, but also every quality assessment item including randomization, blinding should be stated in more detail in protocol.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.2 s.302
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• pp.87-100
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• 2005

In this paper, we propose a new selective temporal error concealment algerian best suited for H.264/AVC. The proposed algorithm performs selective temporal error concealment depending on whether the lost block is at background or foreground. It the corrupted macroblock is decided as at background, then the simple temporal replacement is performed. Also we propose replacing a lost block at foreground with the selective average of respectively estimated blocks from the multiple reference frames. This paper supposes error-corrupted H.264/AVC video bitstreams over CDMA2000 (or UMTS) air interface. It is shown that under Flexible Macroblock Ordering (FMO) coding of H.264/AVC, the proposed algorithm provides PSNR gain up to 1.18dB compared to built-in algorithm in the K264/AVC test model. In addition, the proposed error concealment method has average PSNR improvement of 0.33dB compared with that under N-slice coding mode. The proposed algorithm also provides better subjective video quality than other conventional error concealment algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9C
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• pp.712-719
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• 2008

Temporal error concealment indicates the algorithm that restores the lost video data using temporal correlation between previous frame and current frame with lost data. It can be categorized into the methods of block-based and pixel-based concealment. The proposed method in this paper is for pixel-based temporal error concealment using affine transform. It outperforms especially when the object or background in lost block has geometric transform which can be modeled using affine transform, that is, rotation, magnification, reduction, etc. Furthermore, in order to maintain good performance even though one or more motion vector represents the motion of different objects, we defines a cost function. According to cost from the cost function, the proposed method adopts affine error concealment adaptively. Simulation results show that the proposed method yields better performance up to 1.9 dB than the method embedded in reference software of H.264/AVC.

• Journal of Broadcast Engineering
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• v.20 no.4
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• pp.533-544
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• 2015

Recently, most of the video services are usually transmitted in wireless networks. In networks environment, a packet of video is likely to be lost during transmission. For this reason, this paper proposes a new Error Concealment (EC) algorithm. For High Efficiency Video Coding (HEVC) bitstreams, the proposed algorithm includes Adaptive Prediction Unit-based Motion Vector Extrapolation (APMVE) and Boundary Matching (BM) algorithm, which employs both the temporal and spatial correlation. APMVE adaptively decides a Error Concealment Basic Unit (ECBU) by using the PU information of the previous frame and BM employing the spatial correlation is applied to only unreliable blocks. Simulation results show that the proposed algorithm provides the higher subjective quality by reducing blocking artifacts which appear in other existing algorithms.

• Journal of Broadcast Engineering
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• v.9 no.4 s.25
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• pp.446-454
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• 2004

With the growth of multimedia systems, compressing image data has become more important in the area of multimedia services. Since a compressed image bitstream can often be seriously distorted by various types of channel noise, an error concealment algorithm becomes a very important issue. In order to solve this problem, Hsia proposed the error concealment algorithm where he recovered lost block data using 1D boundary matching vectors. His algorithm, however, requires high computational complexity since each matching vector needs MAD (Mean Absolute Difference) values of all pixels, which is either a boundary line top or a boundary line bottom of a damaged block. We propose a hierarchical search-based fast error concealment scheme as well as its approximated version to reduce computational time. In the proposed scheme, a hierarchical search is applied to reduce the number of checking points for searching a vector. The error concealment schemes proposed in this paper can be about 3 times faster than Hsia's with keeping visual quality and PSNR.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.505-516
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• 2018

The purpose of the present study was to examine the mediating effect of self-concealment on the relationship between self-critical perfectionism and disordered eating behavior. Toward this aim, 348 participants responded to the measures of self-critical perfectionism, self-concealment and disordered eating behavior. Correlation analysis revealed that self-critical perfectionism was positively correlated with self-concealment and disordered eating behavior. In addition, self-concealment was positively correlated with disordered eating behavior. Structural equations analysis found that the relationship between self-critical perfectionism and disordered eating behavior had a significant partial mediating effect on self-concealment, meaning that self-critical perfectionism increased disordered eating behavior through high levels of self-concealment. This finding suggests that individuals who place high standards on themselves, and feature fear of negative evaluation from others, are at greater risk for disordered eating behavior. Based on this finding, we discussed suggestions for future research and clinical implications.