• Journal of Biomedical Engineering Research
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• v.44 no.1
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• pp.19-24
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• 2023

Due to the spread of COVID-19, many patients with severe respiratory diseases have occurred worldwide, and accordingly, the use of mechanical ventilators has exploded. However, hospitals do not have systematic risk management, and the Medical Device Regulation also provides medical device risk management standards for manufacturers, but does not apply to devices in use. In this paper, we applied the Failure Mode Effects Analysis (FMEA) risk analysis technique based on the International Standard ISO 14971 (Medical Devices-Application of risk management to medical devices) for 85 mechanical ventilators of a specific model in use in hospitals. Failure modes and effects of each parts were investigated, and risk priority was derived through multiplication of each score by preparing criteria for severity, occurrence, and detection for each failure mode. As a result, it was confirmed that the microprocessor-based Patient Unit/Monitoring board in charge of monitoring scored the highest score with 36 points, and that reliability management is possible through systematic risk management according to priority.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.35-38
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• 1995

We proposed in this paper a systematic way for analyzing discrete event dynamic systems to classify faults and failures quantitatively and to find tolerable fault event sequences embedded in the system. An automated failure diagnosis scheme with respect to the nominal normal operating event sequences and the supervisory control problem for tolerable fault event sequences is presented. Moreover the supervisor failure diagnosis problem with respect to the tolerable fault event sequences is considered. Finally, a plasma etching system example is presented.

• Korean Journal of Computational Design and Engineering
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• v.18 no.4
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• pp.250-257
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• 2013

This paper introduces a failure analysis procedure that underpins real-time fault prognosis. In the previous study, we developed a systematic eventization procedure which makes it possible to reduce the original data size into a manageable one in the form of event logs and eventually to extract failure patterns efficiently from the reduced data. Failure patterns are then extracted in the form of event sequences by sequence-mining algorithms, (e.g. FP-Tree algorithm). Extracted patterns are stored in a failure pattern library, and eventually, we use the stored failure pattern information to predict potential failures. The two practical case studies (marine diesel engine and SIRIUS-II car engine) provide empirical support for the performance of the proposed failure analysis procedure. This procedure can be easily extended for wide application fields of failure analysis such as vehicle and machine diagnostics. Furthermore, it can be applied to human health monitoring & prognosis, so that human body signals could be efficiently analyzed.

• Proceedings of the KIEE Conference
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• 2006.10b
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• pp.204-207
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• 2006

Prevention of electrical and mechanical accidents from consumer switches needs early to detect and repair failure parts of the switches. But, safety accidents by the switches of consumers occur from non-systematic safety inspection techniques. So, we develope and propose the safety inspection techniques of the consumer switches.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.3
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• pp.162-173
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• 2020

Dental implants are the first option for replacement of missing teeth. Failure usually involves additional cost and procedures. As a result, the physician should limit the risk factors associated with implant failures. Implant site is one of many factors that can influence the success or failure of dental implants. The association between early implant failure (EIF) and implant site has yet to be documented. This review aims to estimate the impact of insertion site on the percentage of EIFs. An electronic and manual search of studies that reported early failure of dental implants based on collection site. A total of 21 studies were included in the review and examined for the association between EIF and alveolar site. Subgroup analysis, including a comparison between implants inserted in four alveolar ridge regions of both jaws was performed. The early failure rate was higher for maxillary implants (3.14%) compared to mandibular implants (1.96%). Applying a random effect, risk ratio (RR), and confidence interval (CI) of 95% revealed higher failure in the maxilla compared to the mandible (RR 1.41; 95% CI [1.19, 1.67]; P<0.0001; I²=58%). The anterior maxilla is more critical for early implant loss than other alveolar bone sites. Implants in the anterior mandible exhibited the best success rate compared of the sites.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.1055-1058
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• 1988

A systematic way of failure diagnosis in a linear system with decentralized estimators is developed. The generalized likelihood ratio (G.L.R) approach to failure detection and identification is used for designing a diagnosis system in each subsystem based on the innovation analysis. For the simplicity of the theoretical formulation, a design scheme of failure diagnosis is developed for the system decomposed into two subsystems. To demonstrate the effectiveness of our approach, several simulation studies have been carried out on a third-order linear system which is constructed of a second-order damped oscillator and a first-order lag.

• Clinical and Experimental Reproductive Medicine
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• v.48 no.3
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• pp.203-210
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• 2021

We performed a systematic review and meta-analysis to evaluate whether intralipid administration improved the outcomes of in vitro fertilization. Online databases (PubMed, Cochrane Library, Medline, and Embase) were searched until March 2020. Only randomized controlled trials (RCTs) that assessed the role of intralipid administration during in vitro fertilization were considered. We analyzed the rates of clinical pregnancy and live birth as primary outcomes. Secondary outcomes included the rates of chemical pregnancy, ongoing pregnancy, and missed abortion. We reviewed and assessed the eligibility of 180 studies. Five RCTs including 840 patients (3 RCTs: women with repeated implantation failure, 1 RCT: women with recurrent spontaneous abortion, 1 RCT: women who had experienced implantation failure more than once) met the selection criteria. When compared with the control group, intralipid administration significantly improved the clinical pregnancy rate (risk ratio [RR], 1.48; 95% confidence interval [CI], 1.23-1.79), ongoing pregnancy rate (RR, 1.82; 95% CI, 1.31-2.53), and live birth rate (RR, 1.85; 95% CI, 1.44-2.38). However, intralipid administration had no beneficial effect on the miscarriage rate (RR, 0.75; 95% CI, 0.48-1.17). A funnel plot analysis revealed no publication bias. Our findings suggest that intralipid administration may benefit women undergoing in vitro fertilization, especially those who have experienced repeated implantation failure or recurrent spontaneous abortion. However, larger, well-designed studies are needed to confirm these findings.

• Journal of Korean Society for Quality Management
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• v.47 no.3
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• pp.641-659
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• 2019

Purpose: Recently, the managing customer complaints properly has emerged as key source of competitive advantage in the large distribution industry. Effective customer complaint management helps firms minimize service failures and incense the capability to respond to customer's needs. Despite this importance, the in-depth prior study of a firm's service failures is very limited. Therefore, the actual service failure cases of large discount stores in Korea were analyzed in this study, and the types of service failures that occur at the service interface were identified. Method: Specifically, a total of 48,307 cases of customer complaints that have occurred in the past three years were collected from 1 January 2016 to 31 December 2018. Using 7 dimensions of service marketing mix. we have classified and analyzed systematically the service failure cases collected. Results: Among the cases of service failures, 34,921 (72.3%) cases were involved with the product factor, followed by 6,152 (12.7%) cases with person factor and 5,392 (11.2%) cases with process factor. Conclusion: By linking the main causes of service failure with the service marketing mix variables, this research presented a more systematic analytic model and verified by applying it to large domestic distribution company. Understanding the main factors affecting customer complaints n the large distribution industry can provide managers useful information and insight who want to achieve an effective customer complaint management.

• Journal of radiological science and technology
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• v.22 no.2
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• pp.33-39
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• 1999

This paper included a data analysis of the unit of medical devices using mainternance recording card that had medical devices of unit failure mode, hospital of failure mode and MTBF. The results of the analysis were as follows : 1. Medical devices of unit failure mode was the highest in QC/PM such A hospital as 33.9%, B hospital 30.9%, C hospital 30.3%, second degree was the Electrical and Electronic failure such A hospital as 23.5%, B hospital 25.3%, C hospital 28%, third degree was mechanical failure such A hospital as 19.5%, B hospital 22.5%, C hospital 25.4%. 2. Hospital of failure mode was the highest in Mobile X-ray device(A hospital 62.5%, B hospital 69.5%, C hospital 37.4%), and was the lowest in Sono devices(A hospital 16.76%, B hospital 8.4%, C hospital 7%). 3. Mean time between failures(MTBT) was the highest in SONO devices and was the lowest in Mobile X-ray devices which have 200 - 400 failure hours. 4. Anverage failure ratio was the highest in Mobile X-ray devices(A hospital 31.3%, B hospital 34.8%, C hospital 18.7%), and was the lowest in Sono(Ultrasound) devices (A hospital 8.4%, B hospital 4.2%, C hospital 3.5%). 5. Failure ratio results of medical devices according to QC/PM part of unit failure mode were as follows ; A hospital was the highest part of QC/PM (50%) in Mamo X-ray device and was the lowest part of QC/PM(26.4%) in Castro X-ray. B hospital was the highest part of QC/PM(56%) in Mobile X-ray device, and the lowest part of QC/PM(12%) in Gastro X-ray. C hospital was the highest part of QC/PM(60%) in R/F X-ray device, and the lowest a part of QC/PM(21%) in Universal X-ray. It was found that the units responsible for most failure decreased by systematic management. We made the preventive maintenance schedule focusing on adjustement of operating and dust removal.

• Geomechanics and Engineering
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• v.28 no.4
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• pp.335-346
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• 2022

Buckling failure is a typical slope instability mode that should be paid more attention to. It is difficult to provide systematic guidance for the monitoring and management of such slopes due to unclear mechanism. Here we examine buckling failure as the potential instability mode for a slope above a railway tunnel in southwest China. A comprehensive model test system was developed that can be used to conduct buckling failure experiments. The displacement, stress, and strain of the slope were monitored to document the evolution of buckling failure during the experiment. Monitoring data reveal the deformation and stress characteristics of the slope with different slipping mass thicknesses and under different top loads. The test results show that the slipping mass is the main subject of the top load and is the key object of monitoring. Displacement and stress precede buckling failure, so maybe useful predictors of impending failure. However, the response of the stress variation is earlier than displacement variation during the failure process. It is also necessary to monitor the bedrock near the slip face because its stress evolution plays an important role in the early prediction of instability. The position near the slope foot is most prone to buckling failure, so it should be closely monitored.