• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.36 no.9
• /
• pp.678-684
• /
• 1987

The identification problem of instrument faults in PWR pressurizer is considered. The instrument failure detection technique in this paper consists of two filters, a normal-mode Kalman filter which estimates plant states in normal operation and a bias estimator which estimates the magnitudes and directions of bias faults. The concept of threshold based on the residual of a Kalman filter in normal operation is introduced. The bias estimator is driven when the absolute value of residual exceeds the threshold. The suggested failure detection algorithm is applied to a PWR pressurizer. Computer simulations show that the prompt detection of bias fault can be performed very successfully when there exist instrument faults.

• Nuclear Engineering and Technology
• /
• v.28 no.6
• /
• pp.551-562
• /
• 1996

This paper introduces the five-step methodology for identifying information needs and assessing instrument availability during the course of severe accidents in nuclear power plants. The methodology is applied to the Yonggwang (YGN) 3&4 to shed light on accident management. It constructs three safety objective trees to prevent the reactor vessel failure, to prevent the containment failure, and to mitigate the fission product release from the containment. The study assesses information needs and instrument availability under severe conditions for preventing the reactor vessel failure of YGN 3&4, and recommends additional instrument that m8y prove to be of vital importance in managing the accident.

• The Mathematical Education
• /
• v.49 no.4
• /
• pp.501-522
• /
• 2010

In this study, 'Instruments of the achievement attribution in mathematical learning' was develop to investigate the reasons of mathematical learning achievement by reflecting Korean middle school and high school students' psychological characters and learning context in mathematical learning. To develop the appropriate items for the achievement attribution in mathematical learning, after reviewing attribution literature thoroughly, first version of the instrument was developed and Exploratory Factor Analysis and Confirmatory Factor Analysis were conducted. Then, to reduce the effect of the gender difference and achievement level difference, Differential Item Functioning was performed. Also, using Multiple group Confirmatory Factor Analysis, this instrument was investigated to see whether this can be used for both middle school and high school. The final items for success attribution are 3 items for luck, 3 items for effort, 2 items for ability. The failure attribution were composed of 3 items for luck, 3 items for effort, 2 items for ability, and 2 items for other. The instrument was developed by using large samples and psychometric analysis. Therefore, mathematic teachers can use this instrument efficiently to make a foundation for better learning environment so students' cognitive area and affective area can be harmonized.

• Journal of the Korea Furniture Society
• /
• v.11 no.1
• /
• pp.25-29
• /
• 2000

This study was carried out to analyze the ultrasonic properties of sound board which was glued with various adhesives and to evaluate which adhesive is the best for the acoustic radiation of the musical instrument. The results are as follows: 1. Animal glue is the best adhesive for the sound board with respect to the acoustic radiation ratio of the musical instruments. Epoxy resin and polyvinyl acetate resin are the next group, urea formaldehyde resin and Hot melt are the third group, polychloroprene(CR) resin is the lowest. 2. Epoxy resin, animal glue and Titebond(PVA) give the highest shear strength and the highest wood failure relatively Hot melt and polychloroprene(CR) resin do not meet the standard because of low wood failure.

• Journal of Korean Neurosurgical Society
• /
• v.30 no.4
• /
• pp.493-500
• /
• 2001

Objective : Anterior cervical locking plates are the devices for achieving anterior cervical spinal fusion. This study was conducted to evaluate the locking plate system regarding its long-term advantages and disadvantages in the view of interbody fusion rate, hardware-related failures, vertebral change close to the fusion segment and postoperative complications. Method : Eight-six patients, operated from Jan., 1996 to Jun. 1998, were followed-up for more than two years. All of the cases were fused with iliac bone graft and ORION locking plate(Sofamor Danek USA, Inc., Memphis, TN) fixation. The patients were discharged or transferred to rehabilitation department 2-7 days after operation. A comprehensive evaluation of the interbody fusion state, instrument failure, vertebral change and postoperative complications were made by direct interview and cervical flexion-extension lateral plain films. Results : There were 55 male and 31 female with a mean age of 45 years(18-75 years). The mean follow-up period was 29 months(24-43 months). Various disorders that were operated were 40 cervical discs, 6 cervical stenosis including OPLL, 2 infections, and 38 traumas. Fusion level was single in 59 cases, two levels of each disc space in 15 cases, and two levels after one corpectomy in 12 cases. There was no instrument failure. Pseudoarthrosis was observed in two cases(2%) without radiological instability. The other patients(98%) showed complete cervical fusion with stable instrument. Mild settling of interbody graft with upward migration of screws was found in 12 cases(14%). Anterior bony growth at the upper segment was found in 5 cases(6%). Postoperative foreign body sensation or dysphagia was observed in 12 cases(4%), and disappeared within one month in 7 cases and within six months in 4 cases. One patient complained for more than six months and required reoperation to remove paraesophageal granulation tissue. Conclusion : The results show that Orion cervical locking plate has some disadvantages of upward migration of screws, anterior bony growth at the upper segment, or possibility of esophageal compression even though it has advantages of high interbody fusion rate or low instrument failure. Author believe that anterior cervical locking plate in the future should be thinner, and should have short end from the screw hole, and movable screw with adequate stability.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.874-882
• /
• 2009

Continuous monitoring of dam performance is essential to earth and rockfill dams safety because it has to be guaranteed for safety during construction period of course and from initial impounding to a long term maintenance period of dam. Among the 31 dams managed by Kwater at present, the proportion of dams being over 20 years after completion of construction is 42% and it is estimated that the loss rate of monitoring devices will be increase as times. Monitoring devices would be impossible to repair since those are mostly installed in the dam body and foundation. If repairing of monitoring devices is possible, the expenditure will be expensive. Therefore reasonable decision making for abandonment, repair and alternation for loss of monitoring devices would be needed through the establishment of key instrument for earth and rockfill dam safety. In this study the process of monitoring for safety were modeled by failure modes of dams, adverse conditions related to failure mode, indicators of adverse condition and monitoring devices The relationship between failure mode and monitoring devices were systematically analyzed and established and evaluation technique for qualifying the importance of monitoring devices were presented.

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

• Journal of the Korean Society of Safety
• /
• v.20 no.3 s.71
• /
• pp.1-8
• /
• 2005

The industrial induction motor is widely used in the rotating electrical machine for the transmission of power. It is very reliable equipment, but it could lead to the loss of production and lift when failure occurs. Therefore, the failure data is acquired and analyzed by attaching an exclusive instrument to existing induction motor. However, these instruments could lead to side effects, increasing the production costs, because they are very expensive. The purpose of this study is the development of an induction motor bearing failure diagnosis system constructed using LabVIEW which can be supplied the kernelled function, process monitoring and current signature analysis. In addition, the availability and reasonability of the constructed system was examined for an induction motor with failure defects in outer raceway and ball bearing. From the results, it shows that failure diagnosis system constructed is useful for real-time monitoring with detection of bearing defects over the web.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.16 no.1
• /
• pp.150-155
• /
• 2010

Purpose: The purpose of this study is to develop evidence-based nursing practice guidelines for hemodialysis in the renal failure patients with risk of bleeding and to evaluate the guidelines by applying it to the practice. Method: Referring to the SIGN, the first draft for guidelines was developed based on the advices and recommendations obtained from the procedure of critical literature analysis. Then, the draft was modified by the procedures of the expert group evaluation and pilot application to the practice. The final draft was evaluated by the expert group using AGREE instrument. Result: The first draft of guidelines was developed through 8 stages of process and was evaluated by seven experts in terms of the appropriateness, applicability, and effectiveness using a 9 point scale. The mean score of 11 items was 7.90 or above. The quality of the final draft was evaluated by 5 experts using the AGREE instrument. The mean standard score was 73.0% or above in the 19 items. Conclusion: The clinical guidelines developed by this research can be utilized as systematic and scientific guidelines for hemodialysis in the renal failure patients with risk of bleeding. In addition, the research can contribute to improving care services.

• Nuclear Engineering and Technology
• /
• v.44 no.4
• /
• pp.405-414
• /
• 2012

In this paper, we propose a reliability estimation method for DI&C systems. At the system level, a fault tree model is suggested and Boolean algebra is used to obtain the minimal cut sets. At the component level, an exponential distribution is used to model hardware failures, and Bayesian estimation is suggested to estimate the failure rate. Additionally, a binomial distribution is used to model software failures, and a recently developed software reliability estimation method is suggested to estimate the software failure rate. The overall system reliability is then estimated based on minimal cut sets, hardware failure rates and software failure rates.