• Nuclear Engineering and Technology
• /
• v.51 no.3
• /
• pp.692-701
• /
• 2019

Recently, instrumentation and control (I&C) systems in nuclear power plants have undergone digitalization. Owing to the unique characteristics of digital I&C systems, the reliability analysis of digital systems has become an important element of probabilistic safety assessment (PSA). In a reliability analysis of digital systems, fault-tolerant techniques and their effectiveness must be considered. A fault injection experiment was performed on a safety-critical digital I&C system developed for nuclear power plants to evaluate the effectiveness of fault-tolerant techniques implemented in the target system. A software-implemented fault injection in which faults were injected into the memory area was used based on the assumption that all faults in the target system will be reflected in the faults in the memory. To reduce the number of required fault injection experiments, the memory assigned to the target software was analyzed. In addition, to observe the effect of the fault detection coverage of fault-tolerant techniques, a PSA model was developed. The analysis of the experimental result also can be used to identify weak points of fault-tolerant techniques for capability improvement of fault-tolerant techniques

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.1301-1303
• /
• 1996

A new automatic frequency control(AFC) tracking algorithm, which we call a rotational decision directed AFC(RDDAFC) is proposed for QPSK demodulation at the digital direct broadcasting satellite(DBS). In order to prevent the presence of the residual phase difference between symbols received at k and k-l by the CPAFC[1] as well as the AFC based on $tan^{-1}$ circuit[2], the RDDAFC rotates the decision boundary for the kth received symbol by the frequency detector output of the (k-1)th received symbol before passing through the cross product discriminator. Test results show that the total pull-in time of the RDDAFC and PLL was 0.13msec under a carrier frequency offset of 2.4MHz when S/N equals 2dB.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10a
• /
• pp.556-558
• /
• 1990

A method of model reduction for reducing a higher order Z-transfer function to its lower order model is developed based on the Block - pulse function. The approach is following : I. Block - pulse function can be applied for Z-transfer function of linear digital system described by high order. II. To determined both the coefficients of the denominator and numerator of reduced model. The proposed method is simple for computation, can preserve the dynamic characteristic of the original model satisfactorily.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.959-962
• /
• 2005

Efficient video data storage and search techniques are essential for DVR-based security systems. We have designed appropriate data structures and search techniques for efficient image storage and search, in this study. The date and time can be saved and searched as a folder form. The overall system is designed for MPEG4 CODEC. It can handle variable sizes of frames (100bytes $^{\sim}$ 6Kbytes) produced by MPEG4 CODEC without errors. We also have developed image transmission techniques through inter-net networking.

• 한국정보통신설비학회:학술대회논문집
• /
• 2004.08a
• /
• pp.119-123
• /
• 2004

이 논문의 목적은 Linux 기반의 서버/클라이언트 구조에서 IPMP 시스템을 구현하는데 있다. DRM(Digital RIghts Management)솔루션을 제공해주는 IPMP(Intellecutual Property Management and Protection)의 참조 소프트웨어인 OpenIPMP 시스템을 기반으로 하며 MPEG-21 권리표현 언어인 XML을 채용하여 새로운 미디어 서비스 환경에 적합한 웹기반 멀티미디어 컨텐츠 서비스 제공 시스템을 구현하는데 있다.

• Proceedings of the KIEE Conference
• /
• 2007.10a
• /
• pp.101-102
• /
• 2007

Heart diseases are critical and should be detected as soon as possible. A stethoscope is a simple device to find cardiac disorder but requires keen experiences in heart sounds. We evaluate a cardiac disorder classifier by using heart sounds recorded by a digital wireless stethoscope developed in this work. The classifier uses hidden Markov models with circular state transition to model the heart sounds. We train the classifier using two kinds of data: One recorded by using our stethoscope and the other sampled from a clean heart sound database. In classification experiments using 165 sound clips, the classifier shows the classification accuracy of 82% in classifying 6 cardiac disorder categories.

• 한국정보통신설비학회:학술대회논문집
• /
• 2005.08a
• /
• pp.323-328
• /
• 2005

이 논문에서는 Linux 기반의 서버/클라이언트 구조에서 H.264 Content에 대한 IPMP 시스템을 구현하고자 한다. DRM(Digital RIghts Management)솔루션을 제공해주는 IPMP(Intellecutual Property Management and Protection)를 관련 참조 소프트웨어들의 변경 통합과정을 거쳐 H.264에 대한 IPMP 시스템을 구현했다.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.6 no.3
• /
• pp.210-216
• /
• 2006

In the rule based modeling, data partitioning plays crucial role be cause partitioned sub data set implies particular information of the given data set or system. In this paper, we present an empirical study result of the data pattern estimation to find underlying data patterns of the given data. Presented method performs crisp type clustering with given n number of data samples by means of the sequential agglomerative hierarchical nested model (SAHN). In each sequence, the average value of the sum of all inter-distance between centroid and data point. In the sequel, compute the derivation of the weighted average distance to observe a pattern distribution. For the final step, after overall clustering process is completed, weighted average distance value is applied to estimate range of the number of clusters in given dataset. The proposed estimation method and its result are considered with the use of FCM demo data set in MATLAB fuzzy logic toolbox and Box and Jenkins's gas furnace data.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.2
• /
• pp.25-33
• /
• 2007

In this paper, a fourth-order single-bit delta-sigma modulator is presented and implemented. The loop-filter is composed of both feedback and feedforward paths. Measurement results show that maximum 99dB dynamic range is achievable at a clock rate of 3.2MHz for 20kHz baseband. The proposed modulator has been fabricated in a $0.18{\mu}m$ standard CMOS process.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.23 no.1
• /
• pp.101-113
• /
• 1986

In this paper, a real-time pitch detector LPC vocoder as implemented on a high speed digital signal processor, NEC 7720, is described. The pitch detector was based mainly on the SIFT algorithm. The SIFT pitch detector consists primarily of a digital low pass filter, inverse filter, computation of autocorrelation, a peak picker, interpolation, V/UV defcision and a final pitch smoother. In our approach, modification, mainly on the V/UV decision and a final pitch smoother, was made to estimate more accurate pitches. An 16-bit fixed-point aithmatic was employed for all necessary computation and the simulated results were compared with the eye detected pitches obtained from real speech data. The pitch detector occupies 98.8% of the instruction ROM, 37% of the data ROM, and 94% of internal RAM and takes 15.2ms to estimate a pitch when an analysis frame is consisted of 128 sampled speech data. It is observed that the tested results were well agreed with the computer simulation results.