• 비파괴검사학회지
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• 제35권6호
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• pp.421-428
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• 2015

An important trend in the sustainment of military aircraft is the transition from preventative maintenance to condition based maintenance (CBM). For CBM, it is essential that the actual system condition can be measured and the measured condition can be reliably extrapolated to a convenient moment in the future in order to facilitate the planning process while maintaining flight safety. Much research effort is currently being made for the development of technologies that enable CBM, including structural health monitoring (SHM) systems. Great progress has already been made in sensors, sensor networks, data acquisition, models and algorithms, data fusion/mining techniques, etc. However, the transition of these technologies into service is very slow. This is because business cases are difficult to define and the certification of the SHM systems is very challenging. This paper describes a possibility for fielding a SHM system on legacy military aircraft with a minimum amount of certification issues and with a good prospect of a positive return on investment. For appropriate areas in the airframe the application of SHM will reconcile the fail-safety and slow crack growth damage tolerance approaches that can be used for safeguarding the continuing airworthiness of these areas, combining the benefits of both approaches and eliminating the drawbacks.

• 한국전산구조공학회논문집
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• 제22권1호
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• pp.15-23
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• 2009

압축력에 강한 석조 홍예아치교의 경우 재료적 음력한계보다는 구조적 형상의 불안정성에 의해서 구조물이 붕괴된다. 이러한 특성을 고려하면, 석조 홍예아치교의 구조적 안정성 평가에는 구조물의 붕괴기구 형상에 초점을 둔 한계상태 해석이 보다 적합하다. 이 연구에서는 한계상태 해석법을 이용하여 건식법(dry construction)으로 축조된 우리나라 석조 홍예아치교의 구조적 거동을 살펴보고, 이 결과를 구조적 안정성 평가시스템 개발에 이용하고자 한다. 이 연구결과는 우리나라 석조 홍예아치교의 구조적 거동을 이해하는데 도움이 되며, 향후 문화재 유지관리 측면에서 공학적 판단기준을 주리라 기대한다.

• 산업경영시스템학회지
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• 제41권1호
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• pp.94-101
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• 2018

With the development of industrial technology and science, production and manufacturing facilities have been enhanced and improved, and the importance of the safety of workers has also been regulated and limited by various safety management methods. As a way to secure the safety of the workers from the production facility, the fail-safe and fool-proof methods are now being applied. Any possible insecure behavior and unsafe conditions can be removed by adopting the standards and specifications that are now secure the safety of workers and equipment. This research analyzes EN ISO 13849-1 international and European standards during CE certification. In order to secure acceptable reduced risks, the risk assessment process of ISO 12100 and the processes for reducing its risk are applied. In the current ISO 13849-1 standard, the criteria for the required performance level PLr (Required Performance Level) for the applicable risk and safety functions through the risk assessment are subjective and not subdivided. Therefore, the evaluation criteria are likely to cause judge's judgement error due to qualitative judgement. This research focuses on evaluation and acceptable performance level setting for the safety circuit of the equipment. We propose an objective and specific evaluation criteria to secure safety, and the proposed evaluation criteria are applied to the case study of the safety circuit for the equipment. In order to secure the safety of the entire safety circuit, the improvement of the MTTFd and DC level related to the SRP/CS (Safety-Related Parts of Control Systems)' lifetime is required for the future research.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.717-720
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• 2000

Event-driven communication protocols such as CAN(Controller Area Network) have inherent packet delays due to the contention process for the use of network medium. These delays are stochastic in nature because most packets arrive at random time instants. The stochastic property of the delay adversely influences the control system's performance in terms of stability, responsiveness and steady-state error. Another problem for safety-critical application such as brake-by-wire systems is the reliability of the communication modules that can fail abruptly. This paper deals with two methods to overcome the above problems : (i) scheduling method that can maintain packet delays under some acceptable level, and (ii) redundancy management of communication modules that prescribes dual-redundancy modules' behavior when one of them fails.

• 한국가스학회지
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• 제11권1호
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• pp.46-50
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• 2007

LPG저장설비나 용기에서 유입되는 LPG가 기화기로부터 충분한 열을 공급받지 못해 액체 상태로 기화기 출구를 통해 나가게 될 경우를 대비하여 설치한 액 유출 방지장치가 정상적으로 기화기 출구부를 차단하지 못하면 기화기 후단부에 설치한 계량기등이 LPG의 순간적인 부피팽창으로 인하여 고장나거나 파열하게 된다. 따라서 이와 같은 기화기 관련 사고를 분석하기 위하여 새롭게 개발한 투명기화통을 이용하여 기화기의 성능평가 및 액유출 방지장치를 분석하였다. 이로부터 액 유출 방지장치 플로트 밸브의 적절한 비중값과 자연대류만으로 열전달을 수행하는 LPG 기화기에 적합한 온도조절 범위를 결정하였다.

• International Journal of Internet, Broadcasting and Communication
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• 제13권2호
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• pp.136-144
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• 2021

Railroad Systems, which are national infrastructure industries, cause unexpected property and human damage if they fail to function while operating. Accordingly, railroad facilities supporting the railroad system are areas where high reliability and safety are required. However, it is time for systematic and scientific maintenance to be taken away from the traditional maintenance methods, as the nation's railroad facilities are now aging seriously. The purpose of this study was to secure the safety and reliability of the aging railroad communication facilities and to improve their performance. The research subjects were selected as a precision diagnosis process for railroad communication facilities, and improvement points were derived through detailed precision diagnosis process analysis. It is deemed that this study can contribute based on securing stability, improving reliability, and continuous improvement of railroad communication facilities should be conducted in the operation of the entire railroad system.

• 한국안전학회지
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• 제31권2호
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• pp.127-132
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• 2016

In this study, the plan to construct a disaster information categorization system that can be objectively and efficiently performed was suggested in order to perform disaster management task systematically. Recently, the damage of natural disasters is gradually growing larger and faster, increasing the economic loss. Especially, as for the domestic storm damage, the damage from strong wind was found to be greater than the damage from torrential rain. Also, strong wind was found to be inflicting a great damage on human life, property and agricultural crops, so the necessity to study damage restoration from strong wind is increasing. Nevertheless, the damage items categorized in the domestic disaster year book are often comprehensive or unclear in criteria, and thus fail to reflect items or matters due to actual disaster damage. It is difficult to aggregate damage accurately such that it does not correspond to the national compensation scope or the damage amount is calculated according to subjective judgment of the investigator in charge. As such, if the disaster information management is inadequate by not applying accurate categorization criteria from damage amount calculation, there can be an issue with fairness when paying the damage support aid. Therefore, this study suggested a categorization plan for objective and efficient execution of disaster information management task in order to resolve such issues. It is expected that quick and efficient execution would be possible in disaster information management and task procedure domestically by constructing systematic categorization system related to disaster information.

• 한국자동차공학회논문집
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• 제24권1호
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• pp.112-121
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• 2016

AFLS (Adaptive front lighting system) is being applied to improve safety in driving automotive at night. Safe embedded system design for controlling head-lamps is required to improve noise robust ECU hardware and software simultaneously by considering safety requirement of hardware-dependent software under severe environmental noise. In this paper, we propose an adaptive headlight controller with a newly-designed symmetric angle sensor compensator, especially based on the proposed steering-swivel angle lookup table to determine whether the current controlling target is safe. The proposed system includes an additional backup hardware to compare the system status and provides safe swivel-angle management using a controlling algorithm based on the pre-defined lookup table (LUT), which is a symmetric mapping relationship between the requested steering angle and expected swivel angle target. The implemented system model shows that the proposed architecture effectively detects abnormal situations and restores safe status of controlling the light-angle in AFLS operations under severe noisy environment.

• Nuclear Engineering and Technology
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• 제49권2호
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• pp.360-372
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• 2017

Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended because of deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Considering an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive Reactor Cavity Cooling System following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. Although this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability of the Reactor Cavity Cooling System (and the reactor system in general) for the postulated transient event.

• 해양환경안전학회지
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• 제15권2호
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• pp.119-125
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• 2009

최근 민간투자에 의한 사회기반시설 확충, 육상 도로망의 직선화 및 최적화를 위해 항만 및 주요 항로를 횡단하는 해상교량 건설이 활발히 추진되고 있다. 이러한 해상교량 건설에 있어 해상이용자의 통항 안전, 항만 운영의 효율화 및 장기 개발 등에 미치는 영향을 충분히 고려하지 않고 경제적인 측면만을 부각하여 건설되고 있다. 이로 인해 해상교량의 위치 및 규모 결정시 해상교통안전 확보를 요구하는 해상이용자와 해상교량 건설주체와 지속적인 갈등이 반복되고 있는 실정이다. 이러한 문제들의 근본적 원인은 항만의 개발 운영 및 해상교통안전 관점에서 제시된 해상교량 건설시에 필요한 교량규모 및 통항 예상 대상 선박 등에 대한 설계기준 및 절차 통이 없기 때문이다. 이에 본 연구에서는 항만별 해상교량 건설현황을 조사 분석을 통해 국내 해상교량 건설에 따른 절차상의 문제점을 우선 고찰하여 개선 방안을 제시하고자 한다.