• International Journal of Reliability and Applications
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• 제10권1호
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• pp.1-15
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• 2009

Even though the impact of manufacturing quality to reliability is not considered much as well as that of design area, a major cause of an early failure of the product is known as manufacturing problem. This research applies two different types of neural network algorithms, the Back propagation (BP) algorithm and Learning Vector Quantization (LVQ) algorithm, to identify and classify the nonrandom variation pattern on the control chart based on knowledge-based diagnosis of dimensional variation. The performance and efficiency of both algorithms are evaluated to choose the better pattern recognition system for auto body assembly process. To analyze hundred percent of the data obtained by Optical Coordinate Measurement Machine (OCMM), this research considers an application in which individual observations rather than subsample means are used. A case study for analysis of OCMM data in underbody assembly process is presented to demonstrate the proposed knowledge-based pattern recognition system.

• International Journal of Reliability and Applications
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• 제2권4호
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• pp.241-251
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• 2001

In this paper, optimal bum-in time to minimize the total mean cost, which is the sum of manufacturing cost with burn-in and cumulative warranty-related cost, is obtained. When the products with cumulative pro-rata warranty have high failure rate in the early period (infant mortality period), a burn-in procedure is adopted to eliminate early product failures. After burn-in, the posterior product life distribution and the warranty-related cost are dependent on burn-in time; long burn-in period may reduce the warranty-related cost, but it increases the manufacturing cost. The paper provides a methodology to obtain total mean cost under burn-in and cumulative pro-rata warranty. Property of the optimal burn-in time is analyzed, and numerical examples and sensitivity analysis are studied.

• 산업공학
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• 제19권1호
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• pp.19-25
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• 2006

In the development process, the objective of a reliability growth program is to track the increase in system reliability, and determine as early as possible whether or not the system reliability is growing at a sufficient rate to meet the required goal and allocate available resources accordingly. Implementation of this kind of program will provide very useful information on concept selection, product/process reliability, and cost effectiveness without too much time, money and engineering effort being spent on the development of failure suspect parts. The purpose of this research is to present a practical method for efficiently monitoring a reliability growth test process using AMSAA(Army Materiel Systems Analysis Activity) reliability growth model. The presented growth management is a viable method for identifying failure modes, incorporating design changes and monitoring reliability progress on an on-going basis during the early stages of a product development program.

• Journal of Chest Surgery
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• 제25권5호
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• pp.518-525
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• 1992

50 months experience with St-Jude Medical Cardiac Valve Prosthesis The St. Jude Medical valve has become our mechanical valvular prosthesis of choice because of favorable hemodynamic results that associated with marked clinical improvement and low incidence of thromboembolism. The data for this study was collected from April 1986 to May 1990, four years period. There were total of 110 patients[female 53, male 58] in this series with 22 isolated aortic valve, 66 isolated mitral valve, 20 double valve, 2 tricuspid valve replacement. The mean follow up time was 23 months. Postoperatively, 77% of cases were in New York Heart Association[NYHA] functional class I, and mild and moderate symptoms[NYHA II ] were present in 20% and there were very few patients remaining in higher functional classifications. In postoperative echocardiographic study showed marked improved cardiac function. The overall early mortality was 5.4% and was higher after double[13.3%] and mitral valve replacement[5.6%] and the late mortality was one case after mitral valve replacement due to endocarditis. The cause of death in early mortality was attributed to heart failure, acute renal failure, sepsis, etc.

• Clinical Endoscopy
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• 제55권2호
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• pp.287-291
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• 2022

Acute liver failure due to malignant melanoma is uncommon. We presents a case of acute liver failure secondary to hepatic infiltration of a malignant melanoma. An 86-year-old man was admitted with elevated liver enzymes and an increased lactate dehydrogenase level. His condition progressed to acute liver failure, but the etiology of liver failure was unclear. Esophagogastroduodenoscopy was performed to evaluate dyspepsia, which showed signs indicative of malignant melanoma. Based on the endoscopy findings and elevated liver enzyme levels, liver biopsy was performed to confirm the presence of malignant melanoma. Hepatic infiltration of malignant melanoma was observed histologically. However, massive and diffuse liver metastasis is very rare and difficult to identify on imaging studies. If the etiology of liver failure is unclear, diffuse metastatic melanoma infiltration should be considered as differential diagnosis. Early liver biopsy can help to clarify the diagnosis.

• Clinical and Experimental Reproductive Medicine
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• 제44권4호
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• pp.187-192
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• 2017

Although the survival rate of hematologic malignancies in young patients is very high, cytotoxic therapies such as chemotherapy and total body irradiation therapy can significantly reduce a patient's reproductive capacity and cause irreversible infertility. Early ovarian failure also commonly occurs following additional cancer treatment, bone marrow transplantation, or autologous transplantation. Because the risk of early ovarian failure depends on the patient's circumstances, patients with a hematologic malignancy must consult health professionals regarding fertility preservation before undergoing treatments that can potentially damage their ovaries. While it is widely known that early menopause commonly occurs following breast cancer treatment, there is a lack of reliable study results regarding fertility preservation during hematologic malignancy treatment. Therefore, an in-depth discussion between patients and health professionals about the pros and cons of the various options for fertility preservation is necessary. In this study, we review germ cell toxicity, which occurs during the treatment of hematologic malignancies, and propose guidelines for fertility preservation in younger patients with hematologic malignancies.

• Journal of Chest Surgery
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• 제20권4호
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• pp.695-705
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• 1987

This report provides follow - up data on 37 patients, aged 7 days to 25 years [median: 6.5 months], who underwent repair of total anomalous pulmonary venous connection at Seoul national University Hospital between May, 1978 and June, 1987. The patients were 22 males and 17 females and the sex ratio was 1.6 to 1, showing a male predominance. Sixteen patients had supracardiac, 13 cardiac, 3 infracardiac and 5 had a mixed type. The duration of follow up was from 1 month to 60 months [median: 14 months] There were eight early and one late deaths, and the overall mortality was 24%. The deaths during 1 year of life were eight [89%] and only one death [11%] occurred above 1 year of age. The mortality of cardiac type was unusually high, accounting for 56 percent of the total death, which was probably due to the preoperative poor clinical condition such as pulmonary edema and congestive heart failure. The major cause of death was the perioperative myocardial failure, and the survival was closely related to the preoperative clinical status, age and moderately elevated pulmonary arterial pressure, the sign of the elevated pulmonary vascular resistance and pulmonary venous obstruction. Early diagnosis and early application of surgical intervention is essential to the improved postoperative survival

• 시스템엔지니어링학술지
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• 제18권1호
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• pp.84-89
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• 2022

For system maintenance optimization, it is necessary to establish a state information system by CBM+ including CBM and RCM, and sensor selection for CBM+ application requires system process for function model analysis at the early design stage. The study investigated the contents of CBM and CBM+, analyzed the function analysis tasks and procedures of the system, and thus presented a D-FMEA based sensor selection inference methodology at the early stage of design for CBM+ application, and established it as a D-FMEA based sensor selection inference process. The D-FMEA-based sensor inference methodology and procedure in the early design stage were presented for diesel engine sub assembly.

• Journal of Chest Surgery
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• 제23권2호
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• pp.275-284
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• 1990

A serious problem after cardiovascular surgery known as Multiple Organ Failure[MOF] whereby several vital organs successively demonstrate dysfunction in spite of intensive postoperative treatment has recently arisen. We have made a retrospective study of the clinical records of 137 patients who underwent cardiovascular surgery during past two years [1987-1988]. Fourteen patients [10%] developed multi-organ failure postoperatively with the results of seven death [50%]. In fatal group, preoperative poor cardiac function [Cardiac Index<2.0L/min/m2] was considered important prognostic factor and infection 5 disseminated intravascular coagulation complicating gastrointestinal bleeding were the leading cause of death. In conclusion, evaluation of multiple factors concerning multi-organ failure demonstrates preoperative poor functional preservation of vital organs is the main factor. So early diagnosis k management for each of the failing organs & prevention of infection are mandatory of the treatment of these critically ill patients.

• 품질경영학회지
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• 제25권1호
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• pp.156-172
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• 1997

FMEA is a widely used technique to assess or to improve reliability of products at early stage of design and development. In order to implement FMEA effectively, it is important to utilize knowledge or technical know-hows. However, that is very difficult. In fact, if information on the failure modes is enough, it is important to consider a counterplan to eliminate critical failure modes. If engineers do not have such information, however, it is more important to know what failure modes of the component under consideration would undergo. This means that the purposes of performing FMEA varies according to the situation. Therefore, we need different kinds of FMEA charts to meet those purposes. This paper proposes two FMEA charts: one is suitable for detecting potential failure modes and the other is for product improvements.