• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.272-279
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• 2006

In this paper, we evaluate the performance of frame synchronization words of pilot bit patterns which are used for the channel estimation and frame synchronization confirmation in W-CDMA(Wide band Code Division Multiple Access) system. W-CDMA system also uses compressed mode to make measurements from another frequency without a full dual receiver terminal. It is confirmed by using computer simulation that the proposed frame synchronization words also maintain the frame synchronization property in the compressed mode by using the complementary mapping relationship of preferred pair ROC(Receiver Operating Characteristic) curves with probability of detection and false alarm are used to analized the performance of the proposed frame synchronization words by using the various detection metrics such as LLRT(Log Likelyhood Ratio Test), GLRT(Generalied Likelyhood Ratio Test), soft and hard correlation tests in AWGN and Rayleigh fading channels. It is expected that the research results fer the performance of pilot bit patterns of this paper can be useful reference for the design and implementation of frame synchronization in 3rd generation W-CDMA system.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.12
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• pp.66-72
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• 2009

This paper proposes an efficient binary arithmetic encoder for CABAC which is used one of the entropy coding methods for H.264/AVC. The present binary arithmetic encoding algorithm requires huge complexity of operation and data dependency of each step, which is difficult to be operated in fast. Therefore, renormalization exploits 2-stage pipeline architecture for efficient process of operation, which reduces huge complexity of operation and data dependency. Context model updater is implemented by using a simple expression instead of transIdxMPS table and merging transIdxLPS and rangeTabLPS tables, which decreases hardware size. Arithmetic calculator consists of regular mode, bypass mode and termination mode for appearance probability of binary value. It can operate in maximum speed. The proposed binary arithmetic encoder has 7282 gate counts in 0.18um standard cell library. And input symbol per cycle is about 1.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.31-37
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• 2002

전자파 잔향실(Reverberating Shielded Enclosure)의 개념은 전자파 차폐실(Shielded Enclosure)에서 얻어진 측정결과를 개선하기 위하여 1968년도에 제안되었다. 이후 Reverberating 또는 Mode-Stirred Chamber는 EM Immunity 측정뿐만 아니라 EMI측정에서도 많이 적용되어 왔지만, 국제 표준 방식으로 적용되어 오지 못하다가 최근 EMI 복사 전력 측정 및 EM Immunity 측정시설로 유용하게 사용될 수 있다는 점이 부각되어 국제 표준 방식으로 적용하자는 분위기가 무르익어 이에 대한 활발한 논의가 계속되어 오고 있다. 이러한 전자파 잔향실을 이용하여 EMI 및 EMS 시험을 실시할 수 있는 방법을 규격화시키자는 제안이 '96년 프랑스 Mandelieu 국제 전자파 장해 특별위원회(CISPR:International Special Committee on Radio Interference)회의에서 검토된 후 '97년 일본 Yokosuka CISPR 회의에서 정식의제로 채택되었다. 이 안건에 대하여 대부분의 국가들이 제안 취지에 찬성하여 NWIP(New Work Item Proposal) 문서가 각국에서 회람되었다. 초기 전자파 잔향실은 전자파 장해 및 복사 내성 측정을 위한 대용시험 시설로서 1968년 미국 Mendes에 의해 전자파 차폐실 구조에 Stirrer를 이용하여 필드의 균일도를 확보할 수 있다는 전자파 잔향실 개념이 처음으로 제안되었다. 이후 이 분야의 연구는 미국 표준 기술 연구소(NIST: National Institute of Standard and Technology)등에서 연구가 활발히 진행되고 있으며, 국제 표준화 기구인 CISPR에서 전자파 장해 및 내성 시험을 위한 대용시험 시설로서 활용하기 위하여 규격 작업이 진행중에 있다. 또한 최근 전자파 장해 방지를 위한 규제 주파수가 1∼18㎓ 까지 확장됨에 따라 이 주파수 대역에서 시험장으로 활용할 수 있는 전자파 잔향실이 새롭게 부각되고 있다. 전자파 잔향실은 기본적으로 공진 모드를 활용하기 때문에 일정한 크기의 잔향실 내부에서 전자파 균일성을 확보할 수 있는 모드 수에 의해 하한 주파수가 결정되며 충분한 모드 분포상태에서 Stirrer를 사용하여 필드 경계를 이동시킴으로서 확률적으로 균일한 필드분포를 확보하게 된다. 주파수가 증가함에 따라 모드수는 증가하기 때문에 하한 주파수 이상의 대역에 대한 시험시설로 활용할 수 있으며, 특히 ㎓ 대역에서 사용하기에 적합한 대용시험시설이라고 볼 수 있다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.11-18
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• 2010

Tool condition monitoring (TCM) is crucial for improvement of productivity in manufacturing process. However, TCM techniques have not been applied to monitor tool failure in an industrial gear shaving application. Therefore, this work studied a statistical TCM method for monitoring gear shaving tool condition. The method modeled the vibration signal of the shaving process using beta probability distribution in order to extract the effective features for TCM. Modeling includes rectifying for converting a bi-modal distribution into a unimodal distribution, estimating the parameters of beta probability distribution based on method of moments. The performance of features obtained from the proposed method was evaluated and discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.229-236
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• 2003

Artificial neural network has been used for damage assessment by many researchers, but there are still some barriers that must be overcome to improve its accuracy and efficiency. The major problems associated with the conventional artificial neural network, especially the Back Propagation Neural Network(BPNN), are on the need of many training patterns and on the ambiguous relationship between neural network architecture and the convergence of solution. Therefore, the number of hidden layers and nodes in one hidden layer would be determined by trial and error. Also, it takes a lot of time to prepare many training patterns and to determine the optimum architecture of neural network. To overcome these drawbacks, the PNN can be used as a pattern classifier. In this paper, the PNN is used numerically to detect damage in a plate girder railway bridge. Also, the comparison between mode shapes and natural frequencies of the structure is investigated to select the appropriate training pattern for the damage detection in the railway bridge.

• Journal of Korea Game Society
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• v.18 no.1
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• pp.105-114
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• 2018

Various data analysis methods used for customer type analysis are very important for game companies to understand their type and characteristics in an attempt to plan customized content for our customers and to provide more convenient services. In this paper, we propose a k-mode cluster analysis algorithm that uses information uncertainty by extending information entropy to reduce information loss. Therefore, the measurement of the similarity of attributes is considered in two aspects. One is to measure the uncertainty between each attribute on the center of each partition and the other is to measure the uncertainty about the probability distribution of the uncertainty of each property. In particular, the uncertainty in attributes is taken into account in the non-probabilistic and probabilistic scales because the entropy of the attribute is transformed into probabilistic information to measure the uncertainty. The accuracy of the algorithm is observable to the result of cluster analysis based on the optimal initial value through extensive performance analysis and various indexes.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.2 s.314
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• pp.1-11
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• 2007

H.264/AVC uses variable block sizes to achieve significant coding gain. It has 7 different coding modes having different motion compensation block sizes in Inter slice, and 2 different intra prediction modes in Intra slice. This fine-tuned new coding feature has achieved far more significant coding gain compared with previous video coding standards. However, extremely high computational complexity is required when rate-distortion optimization (RDO) algorithm is used. This computational complexity is a major problem in implementing real-time H.264/AVC encoder on computationally constrained devices. Therefore, there is a clear need for complexity reduction algorithm of H.264/AVC such as fast mode decision. In this paper, we propose a fast mode decision with early $P8\times8$ mode rejection based on block size activity using large block history map (LBHM). Simulation results show that without any meaningful degradation, the proposed method reduces whole encoding time on average by 53%. Also the hybrid usage of the proposed method and the early SKIP mode decision in H.264/AVC reference model reduces whole encoding time by 63% on average.

• Journal of Broadcast Engineering
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• v.16 no.3
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• pp.510-519
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• 2011

Intra mode decision is a useful coding tool in Distributed Video Coding (DVC) for improving DVC coding efficiency for video sequences having fast motion. A major limitation associated with the existing intra mode decision methods, however, is that its efficiency highly depends on user-specified thresholds or modeling parameters. This paper proposes an entropy-based method to address this problem. The probabilities of intra and Wyner?Ziv (WZ) modes are determined firstly by examining correlation of pixels in spatial and temporal directions. Based on these probabilities, entropy of the intra and the WZ modes are computed. A comparison based on the entropy values decides a coding mode between intra coding and WZ coding without relying on any user-specified thresholds or modeling parameters. Experimental results show its superior rate-distortion performance of improvements of PSNR up to 2 dB against a conventional Wyner?Ziv coding without intra mode decision. Furthermore, since the proposed method does not require any thresholds or modeling parameters from users, it is very attractive for real life applications.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.3
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• pp.73-80
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• 2010

Complex-valued blind algorithms which are based on constant modulus error and Euclidian distance (ED) between two probability density functions show relatively poor performance in spite of the advantages of information theoretic learning since the inherent characteristics of the constant modulus error prevent the algorithm from coping with the symbol phase rotation caused by the complex channels. In this paper, we show that the symbol phase rotation problem can be avoided and the advantages of information theoretic learning can be preserved by introducing decision-directed mode to the blind algorithm whenever the equalizer output power lies in the neighborhood of multi-modulus levels. Simulation results through MSE convergence and constellation comparison for severely distorted complex channels show significantly enhanced performance of symbol-point concentration and no phase rotation problems caused by the complex channel models.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.1
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• pp.15-23
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• 2005

For reliability assessment for machine tools, failure mode analyses by two viewpoints were studied in this paper. First, this study developed the reliability data analysis program, which searches f3r optimal failure distribution like failure rate or MTBF(Mean Time Between Failure) using failure data and reliability test data of mechanical parts in the web. Moreover, this data analysis program saves both failure data or reliability data and their failure rate or MTBF for database establishment. Second, this paper conducted failure mode analysis through such performance tests as circular movement test and vibration testing for machine tools when reliability data is not available. A developed web-based analysis program shows correlations between failure mode and performance test result and also accumulates all the data. These kinds of data analysis programs and stored data furnish valuable information for improving the reliability of mechanical system.