• Journal of Korean Academy of Nursing
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• v.42 no.1
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• pp.76-84
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• 2012

Purpose: The purpose of this methodological study was to examine the reliability and validity of a translated Korean version of the Critical Care Pain Observation Tool (CPOT) developed for assessment of pain in critically ill nonverbal patients. Methods: A cross-sectional study design was used. Data were collected from a convenience sample of 202 critically ill patients admitted to a university hospital. Upon establishment of content and translation equivalence between the English and Korean version of CPOT, psychometric properties were evaluated. Results: The interrater reliability was found to be acceptable with the weighted kappa coefficients of .81-.88. Significant high correlations between the CPOT and the Checklist of Nonverbal Pain Indicators were found indicating good concurrent validity (r=.72-.83, p<.001). Data showed the area under the ROC curve of 0.86 with a cut-off point of 1, which resulted in 76.9% sensitivity and 88.6% specificity. The mean score of CPOT during suctioning was significantly different from that of before (t= -14.16, p<.001) or 20 minutes after suctioning (t=16.31, p<.001). Conclusion: Results of this study suggest that the CPOT can be used as a reliable and valid measure to assess pain in critically ill nonverbal patients.

• Journal of the Korean Society of Safety
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• v.28 no.6
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• pp.11-16
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• 2013

This paper presents a study on the analyzing reliability of smoke fire detector using accelerated life test. In general, the smoke fire detector is broken by dust which flow in smoke detection chamber. In order to conduct accelerated life test of smoke fire detector dust is set accelerated factor in this paper. The dust is fly-ash which is test particle 5th regulated by KS A 0090. The dust accelerated level is 60 g, 180 g and 360 g and failure time is measured by smoke sensitivity testing. It is considered to failure of detector if detector don't operate within 30 secconds when subjected to an air stream having a velocity of 20 cm/s~40 cm/s containing smoke with a concentration of 15% of rate of light-response of 1 m. The goodness of fit test and mean life prediction conduct using the failure time. The result show that life distribution fits the weibull distribution for failure time data and the mean lifes calculate 22.5 year in domestic product and 14.7 years in overseas product applied dust stress only.

• Advances in aircraft and spacecraft science
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• v.4 no.1
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• pp.53-64
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• 2017

Aerospace Launch Vehicles (ALV) are generally designed with high reliability to operate in complete security through fault avoidance practices. However, in spite of such precaution, fault occurring is inevitable. Hence, there is a requirement for on-board fault recovery without significant degradation in the ALV performance. The present study develops an advanced fault recovery strategy to improve the reliability of an Aerospace Launch Vehicle (ALV) navigation system. The proposed strategy contains fault detection features and can reconfigure the system against common faults in the ALV navigation system. For this purpose, fault recovery system is constructed to detect and reconfigure normal navigation faults based on the sliding mode observer (SMO) theory. In the face of pitch channel sensor failure, the original gyro faults are reconstructed using SMO theory and by correcting the faulty measurement, the pitch-rate gyroscope output is constructed to provide fault tolerant navigation solution. The novel aspect of the paper is employing SMO as an online tuning of analytical fault recovery solution against unforeseen variations due to its hardware/software property. In this regard, a nonlinear model of the ALV is simulated using specific navigation failures and the results verified the feasibility of the proposed system. Simulation results and sensitivity analysis show that the proposed techniques can produce more effective estimation results than those of the previous techniques, against sensor failures.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.311-319
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• 2001

All indices that are now in use assume normally distributed data, and any use of the indices on non-normal data results in inaccurate capability measurements. Therefore, $C_{s}$ is proposed which extends the most useful index to date, the Pearn-Kotz-Johnson $C_{pmk}$, by not only taking into account that the process mean may not lie midway between the specification limits and incorporating a penalty when the mean deviates from its target, but also incorporating a penalty for skewness. Therefore we propose, a new process capability index $C_{psk}$( WV) applying the weighted variance control charting method for non-normally distributed. The main idea of the weighted variance method(WVM) is to divide a skewed or asymmetric distribution into two normal distribution from its mean to create two new distributions which have the same mean but different standard distributions. In this paper we propose an example, a distribution generated from the Johnson family of distributions, to demonstrate how the weighted variance-based process capability indices perform in comparison with another two non-normal methods, namely the Clements and the Wright methods. This example shows that the weighted valiance-based indices are more consistent than the other two methods In terms of sensitivity to departure to the process mean/median from the target value for non-normal process.s.s.s.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1523-1529
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• 2018

Electric vehicles that are currently in operation are being produced domestically. Therefore, there is no great difficulty in receiving or repairing the failed parts or in the overall repair. On the other hand, most of the electric locomotives are manufactured by introducing the parts and technology of foreign vehicle manufacturers. In this paper, conducted a study about life cycle cost analysis of developed auxiliary power unit in 8200 series electric locomotive and suggested cost down method. This confirms the economic benefits of the developed products of the auxiliary power supply compared to the existing products. In addition, a sensitivity analysis of MTBF was conducted to suggest a life cycle cost down method.

• International Journal of Reliability and Applications
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• v.1 no.1
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• pp.27-38
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• 2000

In a recent paper Iskandar ＆ Sandoh (1999) studied an opportunity-based age replacement policy for a system which has a warranty period (0,S]. When the system fails at age x $\leq$ S a minimal repair is performed. If an opportunity occurs to the system at age x, S $\leq$ x $\leq$ T, we take the opportunity with probability p to preventively replace the system, while we conduct a corrective .replacement when its fails in (S,T). Finally, if its age reaches T, we perform a preventive replacement, Under this policy the design variable is T. For the case when opportunities occur according to a homogeneous Poisson process, the long-run average cost of this policy was formulated and studied analytically by Iskandar & Sandoh (1999). The same problem is here analysed by using a graphical technique based on scaled TTT-transforms. This technique gives, among other things, excellent possibilities for different types of sensitivity analysis. We also extend the discussion to the situation when we have to estimate T based on times to failure.

• Journal of the Korean Home Economics Association
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• v.40 no.6
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• pp.85-97
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• 2002

The purpose of this study were to develop a rating scale for screening preschoolers' creative characteristics and to examine the validity and reliability of this scale. The subjects were 85 4-5 year olds, their mothers, and teachers in Seoul. The preliminary scale of the Rating Scale for Creative Characteristics of Preschoolers(RSCCP)'was developed as a 47-item 5-point rating scale and consisted of 5 factors. 5 factors. 5 factors were 'uniqueness=-curiosity', 'openness-humor', 'sensitivity-many interest', 'imagination-playfulness', and 'independence-perseverance'. The inter-correlations among the 5 factors ranged from .31-.71. For the criterion validity, Wallach & Kogan's Creativity Test(Foster, 1971) and children's drawing were used, and for the convergence validity, the scores rated by mothers and the scores rated by leachers were compared. Test-retest reliability was .69 and Cronbach's ${\alpha}$ ranged from .76-.90. There found no significant correlations between the RSCCP scale and the 2 criterion tests, and the paired t-test for the total scores of the scale rated by the mothers and the teachers showed no differences.

• Smart Structures and Systems
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• v.10 no.2
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• pp.89-110
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• 2012

This study was intended to efficiently perform the probabilistic optimal safety assessment of steel cable-stayed bridges (SCS bridges) using stochastic finite element analysis (SFEA) and expected life-cycle cost (LCC) concept. To that end, advanced probabilistic finite element algorithm (APFEA) which enables to execute the static and dynamic SFEA considering aleatory uncertainties contained in random variable was developed. APFEA is the useful analytical means enabling to conduct the reliability assessment (RA) in a systematic way by considering the result of SFEA based on linearity and nonlinearity of before or after introducing initial tensile force. The appropriateness of APFEA was verified in such a way of comparing the result of SFEA and that of Monte Carlo Simulation (MCS). The probabilistic method was set taking into account of analytical parameters. The dynamic response characteristic by probabilistic method was evaluated using ASFEA, and RA was carried out using analysis results, thereby quantitatively calculating the probabilistic safety. The optimal design was determined based on the expected LCC according to the results of SFEA and RA of alternative designs. Moreover, given the potential epistemic uncertainty contained in safety index, failure probability and minimum LCC, the sensitivity analysis was conducted and as a result, a critical distribution phase was illustrated using a cumulative-percentile.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.11a
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• pp.27-31
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• 2003

To maintain serviceability of concrete structure more than proper it is necessary not only predict service life through periodical monitor but also need monitoring system to recognize optimal time and method for repair. Recently, CPGFRP, replacing some GFRP with CF, is developed and used for monitoring concrete fraction. But dramatic resistance change of CPGFRP is showed below 0.5% strain and it is not small strain in terms of monitoring micro crack in concrete. In other word, monitoring with CF is not suitable in low stress hut hight stress. In this study, we accessed applicable possibility and reliability of CPGFRP composite as monitoring sense that is proved very sensitive to stress through domestic and oversea previous study. CPGFRP composite plays a role in specimen like steel and increases flexural strength. CPGFRP composite shows resistance increasement in micro crack. In particular, CPUFRP is more sensitive than strangage in low stress. Resistance change ratio curve is very similar to strain curve so sensitivity and reliability is very excellent to monitor concrete fracture.

• Journal of Welding and Joining
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• v.31 no.5
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• pp.59-63
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• 2013

A bendable electronic module has been developed for a mobile application by using a low-cost roll-to-roll manufacturing process. In flexible embedded electronic module, a thin silicon chip was embedded in a polymer-based encapsulating adhesive between flexible copper clad polyimide layers. To confirm reliability and durability of prototype bendable module, the following tests were conducted: Moisture sensitivity level, thermal shock test, high temperature & high humidity storage test, and pressure cooker tester. Those experiments to induce failure of the module due to temperature variations and moisture are the experiment to verify the reliability. Failure criterion was 20% increase in bump resistance from the initial value. The mechanism of the increase of the bump resistance was analyzed by using non-destructive X-ray analysis and scanning acoustic microscopy. During the pressure cooker test (PCT), delamination occurred at the various interfaces of the bendable embedded modules. To investigate the failure mechanism, moisture diffusion analysis was conducted to the pressure cooker's test. The hygroscopic characteristics of the encapsulating polymeric materials were experimentally determined. Analysis results have shown moisture saturation process of flexible module under high temperature/high humidity and high atmosphere conditions. Based on these results, stress factor and failure mechanism/mode of bendable embedded electronic module were obtained.