• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1253-1258
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• 2004

The system safety must be ensured before customization. There was no specific requirement representing system safety in Korea until now. So we should draw safety requirements to guarantee system safety for the first time. In this paper, the Preliminary Hazard Analysis (PHA) to derive the safety requirements on the train control system was carried out. To analyze hazard, we have to deduce system functions, identify related hazards, derive the effects of the hazards, analyze current risks, define the target risks of the system, and deduce the alternative plans to reduce the effects of the hazards. For the case study, the detailed analysis on vehicle collision that was a main hazard of the train control system was carried out.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.51-54
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• 1992

Protection and control systems play a prominent part in avoiding power delivery interruptions and help to get a fast and secure restoration when a failure occurs. In order to meet the higher functional requirements on modern power system, protection speed, selectivity, sensitivity, dependability, and security are essential to ensure reliability. These functions on be satisfied by taking advantage of microprocessor and communication technologies, and digital protection relays (systems) have been developed and applied to real power system enhancing reliability and saving money. It is necessary to have a tool to analyze the functions and algorithms of digital relays for installing them to power system. The purpose of this study is to develop a digital relay simulation program to estimate digital relay performances during system faults. Components of digital protective relay including analog filter, sampling unit, digital filter, and relay logic are modeled in this program.

• Proceedings of the Korean Reliability Society Conference
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• 2011.06a
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• pp.271-279
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• 2011

Automotive safety integrity level of hardware components can be achieved by satisfying quantitative and qualitative requirements. Based on ASIL, quantitative requirements are composed of hardware architectural metrics and evaluation of safety goal violations due to random hardware failures in ISO 26262. In this paper, the types of hardware failures will be defined and classified. Based on various metrics related with hardware failures, design essentials to achieve hardware safety integrity will be studied specifically. Issues associated with hardware development and assessment process are presented briefly.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.941-946
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• 2007

In this paper, as the step to assess and enhance the reliability of Korean Tilting Train eXpress (T.T.X), Door system is selected and reliability analysis is carried out. The door system is classified into subsystems and functional block diagrams and reliability block diagrams are drawn.Expessions for evaluating the reliability are derived and Mean Kilometer between Service Failure is calculated using the trial track test results. The calculation result show reliability growth of proposed system. This paper developed RAMS to make a door system of T.T.X. (Tilting Train eXpress) with maximum operation speed of 180 km/h.

• International Journal of Quality Innovation
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• v.1 no.1
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• pp.64-74
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• 2000

This paper investigates the issue of performance testing on web browsing environments. Among the typical non-functional characteristics, index of link validity will be deeply explored. A framework to certify link correctness in web site is proposed. All possible navigation paths are first formulated to represent a usage model with the Markov chain property, which is then used to generate test script file statistically. With collecting any existing failure information followed by tracing these testing browsed paths, certification analysis may be performed by applying Markov chain theory. The certification result will yield some significant information such as: test coverage, reliability measure, confidence interval, etc. The proposed mechanism may provide not only completed but also systemic methodologies to find any linking errors and other web technologies errors. Besides, an actual practice of the proposed approach to a web-based system will be demonstrated quantitatively through a certification tool.

• Journal of Chest Surgery
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• v.25 no.12
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• pp.1448-1454
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• 1992

Between July, 1990 and July, 1992, 6 male patients of truncus arteriosus, whose age ranged from 2 months to 18 months, underwent total surgical correction without a extracardiac conduit. Their anatomic types were type I in 3, type II in 2 and III, in one by the Collett-Edwards classification. Surgical techniques were similar to the first description by Lecompte except for the fact that distal pulmonary arterial stumps were approximated to ventriculotomy site without Lecompte maneuver in all cases. Also in all cases, mon-ocusps were placed using glutaraldehyde fixed autologous pericardial patch directly in right ventricular outflow tract. Three patients died postoperatively and the causes of death were myocardial failure, pulmonary hypertensive crisis and pulmonary complication due to progressive pulmonary vascualr obstructive disease respectively. The three survivors have been followed up for 6~10 months with good functional results.

• Journal of Chest Surgery
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• v.16 no.4
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• pp.470-475
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• 1983

Myxoma of the heart can now be successfully treated but the success is obviously dependent upon the correct diagnosis and treatment prior to development of catastrophic complications such as sudden death, embolism or cardiac failure. The right ventricular myxoma is very rare, and we treated successfully a case of giant right ventricular myxoma, sessile tumor originated from ventricular apex, weighed 175 gm. The tumor base was broad, about 3 cm x 3cm, and it was hardly adhesed to the tricuspid valvular structures, but could remove with the preservation of adequate residual ventricular chamber size and the maintenance of functional tricuspid valve anatomy. The postoperative course was excellent and uneventful.

• Journal of Chest Surgery
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• v.16 no.4
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• pp.526-532
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• 1983

This is a report of one case of Loffler`s eosinophilic endocarditis associated with mitral insufficiency and LV thrombi treated surgically at the department of Thoracic and Cardiovascular Surgery, Hanyang University Hospital. This patient was a 42 year old female and she has complains of dyspnea, palpitation, orthopnea and generalized edema. Above symptoms has been going for 4 months and NYHA classification was IV. On examination, blood eosinophil was 45 to 50% [WBC-9800 ]. MI and LV thrombi were confirmed by LV ventriculography and echocardiography. Pulmonary congestion and congestive cardiac failure were diagnosis by X-Ray examination, EKG finding and clinical feature and others there were no organic functional disturbance. Mitral valve replacement was performed with Ionescu-Shiley pericardial valve [29mm] replacement. Adjust thumb sized grayish brown colored two thrombi were excluded, lodged in the apex and septal endocardium of LV. Endocardial fibrosis was reliably confirmed under the gross pathology in the heart. The patient had smooth postoperative course and there were no operative complication.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.233-237
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• 2004

In this paper, to assess and enhance the reliability of Korea High Speed Train, electric traction system is selected and reliability analysis is carried out. The electric traction system is classified into subsystems and the functional block diagram and the reliability block diagram are drawn. Expressions to calculate the reliability are deduced and Mean Kilometer Between Service Failure is calculated using the trial test results on the track. Calculated results show reliability growth of the electric traction system.

• Nuclear Engineering and Technology
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• v.45 no.1
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• pp.13-20
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• 2013

This paper looks at the Fukushima disaster from the perspective of resilience engineering, which replaces a search for causes with an understanding of how the system failed in its performance. Referring to the four resilience abilities of responding, monitoring, learning, and anticipating, the paper focuses on how inadequate engineering anticipation or risk assessment during the design, in combination with inadequate response capabilities, precipitated the disaster. One lesson is that systems such as nuclear power plants are complicated, not only in how they function during everyday or exceptional conditions, but also during their whole life cycle. System functions are intrinsically coupled synchronically and diachronically in ways that may affect the ability to respond to extreme conditions.