• Journal of the Korean Society for Aviation and Aeronautics
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• v.27 no.3
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• pp.15-23
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• 2019

This paper contains analyses and development processes of the requirements to detect the possible intermittent failure in an old avionics backplane. Interconnections for signal transmission between electronic components, such as Pin-to-PCB, FPCB-to-FPCB, pin-to-FPCB, and pint-to-wire, were selected as the main cause of intermittent failure by analyzing target equipment and documents. The possibility of detecting intermittent failures occurring in the target equipment is verified by physics-of-failure analyses. In order to verify the occurrence of intermittent failures and their detectability, latching continuity circuit testers were manufactured and accelerated life tests were performed by applying temperature and vibration cycle in consideration of flight conditions. Through the above process, the detection requirements for the major intermittent failure in the target avionics backplane was developed.

• 전기의세계
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• v.27 no.4
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• pp.41-44
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• 1978

Intermittent failures exercise their effects only part of the time but constitute a dominant factor for the field failures. We consider the data raliability of the partially self-checking network with which a single intermittent failure will be recovered by a rollback method. Even if the self-testingness of partially self-checking network is guranteed for a set of permanent failures, it sometimes may not be so for intermittent failures. We introduce the notion of error residual and provide the basis for calculating the data reliability. Both the duration of each intermittent failure and the occurrence interval of successive ones are assumed to be negative exponentially distributed; the convolution of the intervals is distributed according to an Erlangen distribution.

• Journal of Power Electronics
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• v.17 no.3
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• pp.811-820
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• 2017

The reliability issue of IGBT is a concern for researchers given the critical role the device plays in the safety of operations of the converter system. The reliability of power devices can be estimated from the intermittent life test, which aims to simulate typical applications in power electronics in an accelerated manner to obtain lifetime data. However, the test is time-consuming, as testing conditions are not well considered and only rough provisions have been made in the current standards. Acceleration of the test by changing critical test conditions is controversial due to the activation of unexpected failure mechanisms. Therefore, full investigations were conducted on critical test conditions of intermittent life test. A design optimization process for IGBT intermittent life testing program was developed to save on test times without imposing additional failure mechanisms. The applicability of the process has been supported by a number of tests and failure analysis of the test results. The process proposed in this paper can guide the test process for other power semiconductors.

• Journal of Korean Institute of Industrial Engineers
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• v.23 no.1
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• pp.177-196
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• 1997

In this paper, statistically optimal accelerated life test(ALT) plans considering statistical efficiency only and new compromise ALT plans to sacrifice some statistical efficiency in return for improved overall properties including estimobility probability and robustness for the model assumptions are developed under the assumptions of constant stress, intermittent inspection, Type I censoring and lognormal failure distribution which has been one of the popular choices of failure distributions in the extensive engineering applications of ALT. Computational experiments are conducted to compare with four ALT plans including two proposed ones under continuous and intermittent inspections over a range of parameter values in terms of asymptotic variance, sensitivities for guessed input values, and proportion of estimable samples, etc. The small and moderate sample properties for the proposed ALT plans designed under asymptotic criterion are also investigated by Monte Carlo simulation.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.68-75
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• 2018

A flare from an Air Force fighter was abnormally dispensed during the landing. To determine the cause of the abnormal dispensing, fracture analysis, signal analysis and reproduction experiments based on physics of failures were performed. The primary cause of the failure was analyzed to be due to an intermittent fault of an internal circuit card in the AN/ALE-40 chaff/flare dispenser by a broken lid of a capacitor, and the root cause which had derived the primary cause was considered to be an improper handling during the domestic maintenance which were changed from the overseas maintenance due to the DMSMS problem. Therefore, the overall process of the maintenance capability development system was reviewed and alternative ways that considers maintenance error decision aid(MEDA) for system improvement were suggested to prevent further failures.

• Journal of Yeungnam Medical Science
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• v.3 no.1
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• pp.375-382
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• 1986

We studied the effects of the acute intermittent peritoneal dialysis in severe acute renal failure of 1 newborn infant and 2 young infants during 18 months period from February 1985 to April 1986. The predisposing illnesses were severe acute gastroenteritis with dehydration. Reye's syndrome, and bilateral nephrolithiasis with hyperuricemia. The concomittent illnesses were severe hypernatremia, hyponatremia, hyperkalemia, hypocalcemia, hypoglycemia, DIC(disseminated intravascular coagulopathy), paralytic ileus, metabolic acidosis and gastrointestinal bleeding. As a dialvsate, Imperinol $solution^R$, 1.5% was used in all cases. The cycles of dialysis were 8, 16, and 41 times in each cases. Observed complications during dialysis were leakage, and abdominal wall and scrotol swelling in 2 cases, hyperglycemia in 1 case, and peritonitis in 1 case. Acinetobacter calcoaceticus was cultured in peritoneal fluid of peritonitis. These complications were treated by stopping dialysis in leakage and abdiminal wall swelling, insulin therapy in hyperglycemia, and intraperitoneal and systemic antibiotics therapy in peritonitis. We experienced improvements of severe acute renal failure with variable concomittant illnesses by acute intermittent peritoneal dialysis despite of the treatable complications of dialysis in all cases.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.1
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• pp.1-11
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• 2014

The water distribution system should be invariably operated on continuous pattern for 24 hours a day. Occasionally, it is not practically possible to operate for 24 hours due to water shortage or financial constraints. Therefore an intermittent water supply is unavoidable in water shortage area and developing countries. But the intermittent water supply can introduce large pressure forces and rapid fluid accelerations into a water supply network. These disturbances may result in new pipe failure, leakage and secondary contamination. This paper proposed an improvement methodology to prevent the disturbances by intermittent water supply. For the study, the hydraulic variation of intermittent flow in water distribution system was measured and analyzed in the field by comparing with simulation of hydraulic model. Installations of control valves such as, pressure reducing and sustaining and air valves were employed for pressure and flow control. The effectiveness of the methods are presented by comparing hydraulic conditions before and after introducing the proposed solutions.

• Research in Community and Public Health Nursing
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• v.29 no.4
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• pp.467-475
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• 2018

Purpose: The purpose of this study is to investigate adherence to the clean intermittent catheterization (CIC) and influencing factors on the adherence following a customized intensive education program (CIEP). Methods: This work is a retrospective descriptive study. The subjects were 226 emptying failure patients who learned in a CIEP from January 2012 to July 2014. The program developed in 2011 and consisted of 1) customized theoretical education; based on the results of urologic tests, underlying disease, or surgery of the patients, 2) hands-on practice until the trainees were able to master the techniques, 3) questions about the process of catheterization and what he/she needs to know. 4) at follow-up, the survey about adherence and barrier to CIC. Clinical characteristics; the level of satisfaction, understanding, and self-confidence; the barrier in medical records were reviewed. Results: The short-term adherence rate (median 22 days) is 87.6% and the long-term adherence rate (median 112 days) is 50.4%. The biggest obstacle is time management. The levels of satisfaction, understanding, and self-confidence are very high. The variable of Income is the only factor that has influence on adherence. Conclusion: Despite the CIEP, the adherence rate is relatively low. In addition to the education, emotional and psychological supports and regular follow-up are needed to improve long-term adherence.

• Elastomers and Composites
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• v.46 no.2
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• pp.144-151
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• 2011

Intermittent CSR testing was used to investigate the degradation of a hydrogenated NBR(HNBR) O-rings, and also the prediction of its life-time. The cure system of HNBR O-ring was controlled as sulfur cure and peroxide cure system. An intermittent CSR jig was designed taking into consideration the O-ring's environment under use. The testing allowed observation of the effects of friction, heat loss, and stress relaxation by the Mullins effect. Degradation of O-rings by thermal aging was observed between 100 and $120^{\circ}C$. In the temperature range of $100-120^{\circ}C$, O-rings showed linear degradation behavior and satisfied the Arrhenius relationship. The activation energy of HNBR-S was about 70.6 kJ/mol. From Arrhenius plots, predicted life-times of HNBR-S O-ring were 31.1 years and 33.7 years for 50% and 40% failure conditions, respectively. In case of HNBR-P, the activation energy was about 72.1kJ/mol, and predicted life-times were 34.0 years and 36.5 years for 50% and 40% failure conditions, respectively. The peroxide cure system showed slower degradation rate and higher activation energy than the sulfur cure system.

• Journal of Yeungnam Medical Science
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• v.6 no.1
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• pp.205-211
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• 1989

We report a case of acute intermittent porphyria presenting with variable symptoms and signs such as hypertention, polyneuropathy, syndrome of inappropriate secretion of antidiuretic hormone and cerebral infarction. A 47 year-old female patient entered hospital with abdominal pain followed by generalized seizure. She was diagnosed to have acute intermittent porphyria in consequence of Watson-Schwartz test and ${\delta}$-ALA in 24 hours urine, but died of respiratory failure.