• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.4
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• pp.173-178
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• 2008

Electro-hydraulic brake system has many advantages. It provides improved braking performance and stability functions. It also removes complex mechanical parts for freedom of design, improves maintenance requirements and reduces unit weight. However, the EHB system should be dependable and have back-up redundancy in case of a failure. In this paper, the model-based fault diagnosis system is developed to monitor the brake status using the analytical redundancy method. The performance of the model-based fault diagnosis system is verified in real-time simulation. It demonstrates the effectiveness of the proposed system in various faulty cases.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.148-158
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• 1991

The Built-In-Test (BIT) system is an integrated subsystem for the determination of the health status of any primary system. The BIT consists of hardware and software installations directed at performance of the functions of fault detection, diagnosis and isolation, as well as primary system record failure information. Evaluation of the difinitions appropriate to the BIT system, including system characteristics and parameters, is important to an understanding of system functions. The object of this paper is to present general definitions of the BIT diagnosis parameters and a semiquantiative evaluation method for BIT systems. Finally, two case studies for actual problem solutions are included.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.250-255
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• 1993

In this paper, for detection and isolation of instrument and process faults related with steam generator(S/G) in nuclear power plant, two types of observers are designed based on the linearized dynamic model of S/G : a bank of Dedicated Observers (DOS) for instrument faults detection and a bank of Unknown Input Observers(UIO) for process faults detection. And then, they are combined to decide which one between the above two faults occurs. In principle, the failure in ith instrument(process) can be isolated by monitoring the error between the ith output and its estimation obtained from the ith DOS(UIO). It is shown via computer simulations that the present scheme is feasible in finding out the source of a fault.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2198-2202
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• 2005

In this paper we have presented a condition monitoring method of check valve using neural network. The acoustic emission sensor was used to acquire the condition signals of check valve in direct vessel injection (DVI) test loop. The acquired sensor signal pass through a signal conditioning which are consisted of steps; rejection of background noise, amplification, analogue to digital conversion, extract of feature points. The extracted feature points which represent the condition of check valve was utilized input values of fault diagnosis algorithms using pre-learned neural network. The fault diagnosis algorithm proceeds fault detection, fault isolation and fault identification within limited ranges. The developed algorithm enables timely diagnosis of failure of check valve’s degradation and service aging so that maintenance and replacement could be preformed prior to loss of the safety function. The overall process has been experimented and the results are given to show its effectiveness.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.6
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• pp.765-771
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• 1998

An artificial neural network(NN) technique is developed for hardware redundant sensor validation. Since the measurement space is a continuous space with many operating regions, it is difficult to train a NN to correctly detect failure in an accurate measurement system. A conventional backpropagation NN is modified to include an additional preprocessing layer that extracts classification features from scalar measurements. This feature extraction means transform the measurement space to parity space. The NN is independent of the state variable being measured, the instrument range, and the signal tolerance. This NN resembles the parity space approach to signal validation, except that analytical parity equations are unneeded and the NN pattern recognition capability is utilized for decision making.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.1
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• pp.65-70
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• 2013

A 0.18-${\mu}m$ 3.3 V grounded-gate NMOS (GGNMOS) I/O cell array for timing controller (TCON) application is proposed for improving electrical overstress (EOS) robustness. The improved cell array consists of 20 GGNMOS, 4 inserted well taps, 2 end-well taps and shallow trench isolation (STI). Technology computer-aided design (TCAD) simulation results show that the inserted well taps and extended drain contact gate spacing (DCGS) is effective in preventing EOS failure, e.g. local burnout. Thermodynamic models for device simulation enable us to obtain lattice temperature distributions inside the cells. The peak value of the maximum lattice temperature in the improved GGNMOS cell array is lower than that in a conventional GGNMOS cell array. The inserted well taps also improve the uniformity of turn-on of GGNMOS cells. EOS test results show the validity of the simulation results on improvement of EOS robustness of the new GGNMOS I/O cell array.

• Earthquakes and Structures
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• v.9 no.3
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• pp.563-576
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• 2015

Over the past few decades, seismic retrofitting of structural systems has been significantly improved by the adoption of various methods such as FRP composite wraps, base isolation systems, and passive/active damper control systems. In parallel with this trend, probabilistic risk assessment (PRA) for structural and nonstructural components has become necessary for risk mitigation and the achievement of reliable designs in performance-based earthquake engineering. The primary objective of the present study was to evaluate the effect on piping fragility at T-joints due to seismic retrofitting of structural systems with passive energy-dissipation devices (i.e., linear viscous dampers). Three mid-rise building types were considered: without any seismic retrofitting; with distributed damper systems; with optimal placement of dampers. The results showed that the probability of piping system failure was considerably reduced in a Multi Degree of Freedom (MDOF) building retrofitted with optimal passive damper systems at lower floor levels. This effect of damper systems on piping fragility became insignificant as the floor level increased.

• Geotechnical Engineering
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• v.11 no.3
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• pp.139-162
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• 1995

The possibility of the development of gas driven hydrofractures at the Waste Isolation Pilot Plant(WIPP) is investigated through analytical and numerical calculations and through laboratory experiments. First, an investigation of the chemical reactions involved shows that a large volume of gas could potentially be generated through the oxidation of iron in the waste. Simple ground water'flow calculations then show that unless regions of high permeability has been created, this gas volume will build up the pressure high enough to cause tensile damage in the horizontal planes of weakness or in the halite itself. The analytical calculations were performed using the concepts of linear elastic fracture mechanics and the numerical calculations were done using the finite element method. Also, laboratory tests were conducted to illustrate possible failure mechanisms. It is possible that after growing horizontal crack in the weaker anhydride layer, the crack could break out of this layer and propagate upward into the halite and toward the ground surface at an inclined argle of around 53$^{\circ}$ above horizontal. To prevent this latter phenomenon the anhydrite must have a fracture toughness less than 0.5590 times than that of the halite. Through the tests, three types of crack(radial vertical cracks, horizontal circular cracks and cone -shaped cracks) were observed.

• Korean Journal of Veterinary Service
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• v.39 no.2
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• pp.131-136
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• 2016

Clostridium novyi (C. novyi) is a gram positive, non-capsulated, motile, obligatory anaerobe that produces endospores. Both C. novyi type A and B produce a bacteriophage encoded lethal alpha toxin which belongs to a family of large clostridial cytotoxins. These large clostridial cytotoxins of C. novyi bind to the uncharacterized receptors on host vascular endothelial cells, which leads to the loss of integrity of the vascular endothelium with subsequent edema, refractory hypotension, organ failure, and sudden death. A total of 13 sudden death cases were submitted to Chonbuk National University-Veterinary Diagnostic Center between June and October, 2015. The samples, mainly liver, were collected in sterile vials after necropsy and processed within 12~24 hours for diagnosis, isolation and identification of C. novyi. All of the 4 gram positive samples showed amplification by PCR. Out of 4 positive samples, 3 were detected to be C. novyi type B and 1 was detected as C. novyi type A. Based on the 16S rDNA sequence analysis, 1 case (150564) showed 99% similarity with C. novyi type A while other 3 cases (150388, 150557 and 150775) presented 99% similarity with C. novyi type B. Based on the results, C. novyi was found to be prevalent in Korean pig farms and causes sudden death to finishing pigs or sows during summer season. Thus, C. novyi should be considered for differential diagnosis on sudden death cases during the summer season.

• Clinical and Experimental Reproductive Medicine
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• v.23 no.3
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• pp.311-318
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• 1996

Mycoplasmas have long been suspected of contributing to involuntary infertility in couples. However considerable disagreement exits concerning the role of genital mycoplasma infection in human infertility. Several investigators have noted abnormalities in the semen analysis of men with positive mycoplasma cultures, and early epidemiologic studies indicated that Ureaplasma urealyticum was linked to human reproductive failure on the basis of higher frequencies of isolation from infertile versus fertile couples and successful pregnancies in infertile couples after doxycycline therapy. However, subsequent investigators have questioned these findings because there are many studies in which treatment for mycoplasma in the male or female did not demonstrate an improved pregnancy rate, and semen samples from unexplained infertile men containing ureaplasmas have not revealed poorer motility, fewer spermatozoa and more aberrant forms. The objective of this study were to investigate the incidence rate of mycoplasma in semen and to investigate whether the presence of mycoplasma in semen makes significant difference to the semen volume, sperm motility and sperm counts. The results were that the rate of isolation of mycoplasma species was 70.3%. Semen volume is $2.84{\pm}1.01ml$ for culture negative and $3.15{\pm}1.42ml$ for culture positive group. Sperm motility is $46.23{\pm}15.80%$ for culture negative and $50.09{\pm}15.69%$ for culture positive group, and sperm count is $95.47{\pm}47.14({\times}(P)10^6/ml)$ for culture negative and $86.73{\pm}47.59({\times}10^6/ml)$ for culture positive group. In conclusion, we suggest that the presence of mycoplasma in semen makes no significant differences to the sperm parameters.