• Journal of Advanced Navigation Technology
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• v.20 no.4
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• pp.285-291
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• 2016

Safety assessment is an essential activity for developing a system in the CNS/ATM domain. Up to now, there are many reference materials, but there is nothing that definitely specifies what to do and how to apply in the CNS/ATM. Another problem is that software assurance level has to be determined for a software under development. But there is nothing that defines a determination scheme of software assurance level. To solve these problems, this paper proposes a method to conduct a hazard assessment based on target level of safety defined in ICAO Doc 9689. To be applied generally in CNS/ATM domain, it mathematically defines procedures of hazard assessment. And it defines severity classification, probability, and safety objective of a system, which are necessary for hazard assessment, and it describes a method to apply event tree analysis process in order to conduct a hazard assessment.

• Wind and Structures
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• v.24 no.3
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• pp.249-265
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• 2017

An efficient and accurate algorithm is proposed to estimate flutter safety factor of suspension bridges satisfying prescribed reliability levels. Uncertainties which arise from the basic wind speed at the bridge deck location, critical flutter velocity, the wind conversion factor from a scaled model to the prototype structure and the gust speed factor are incorporated. The proposed algorithm integrates the concepts of the inverse reliability method and the calculation method of the critical flutter velocity of suspension bridges. The unique feature of the proposed method is that it offers a tool for flutter safety assessment of suspension bridges, when the reliability level is specified as a target to be satisfied by the designer. Accuracy and efficiency of this method with reference to three example suspension bridges is studied and numerical results validate its superiority over conventional deterministic method. Finally, the effects of various parameters on the flutter safety factor of suspension bridges are also investigated.

• Journal of the Korean GEO-environmental Society
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• v.15 no.2
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• pp.5-15
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• 2014

Target reliability index in the limit state design indicated the safety margin and it is important to determine the partial factor. To determine the target reliability index which is needed in the limit state design, the six design and construction case histories of gravel compaction piles (GCP) were investigated. The limit state functions were defined by bulging failure for the major failure mode of GCP. The reliability analysis were performed using the first order reliability method (FORM) and the reliability index was calculated for each ultimate bearing capacity formulation. The reliability index of GCP tended to be penportional to the safety factor of allowable stress design and average value was ${\beta}$=2.30. Reliability level that was assessed by reliability analysis and target reliability index for existing structure foundations were compared and analyzed. As a result, The GCP was required a relatively low level of safety compared with deep and shallow foundations and the currd t reliability level were similar to the target reliability in the reinforced earth retaining-wall and soil-nailing. Therefore the target reliability index of GCP suggested as ${\beta}_T$=2.33 by various literatures together with the computed reliability level in this study.

• Nuclear Engineering and Technology
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• v.56 no.1
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• pp.147-159
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• 2024

Plutonium-238 has always been considered as the one of the promising radioisotopes for space nuclear power supply, which has long half-life, low radiation protection level, high power density, and stable fuel form at high temperatures. The industrial-scale production of ²³⁸Pu mainly depends on irradiating solid ²³⁷NpO₂ target in high flux reactors, however the production process faces problems such as large fission loss and high requirements for product quality control. In this paper, a conceptual design study of producing ²³⁸Pu in a multi-purpose high flux reactor was evaluated and analyzed, which includes a sensitivity analysis on ²³⁸Pu production and a further study on the irradiation scheme. It demonstrated that the target structure and its location in the reactor, as well as the operation scheme has an impact on ²³⁸Pu amount and product quality. Furthermore, the production efficiency could be improved by optimizing target material concentration, target locations in the core and reflector. This work provides technical support for irradiation production of ²³⁸Pu in high flux reactors.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.4
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• pp.278-289
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• 2009

In the present study, we evaluated the target reliability indices and partial safety factors for caisson sliding of a vertical breakwater. The average of the reliability indices of existing breakwaters was proposed as the target reliability index for the breakwater of normal safety level. The target reliability indices of high and low safety levels were also proposed based on the analysis of breakwaters in Korea and Japan. The partial safety factors were then proposed for each safety level by averaging the values calculated for 12 breakwater crosssections in Korea. The appropriateness of the proposed partial safety factors was partly verified by showing that the reliability index calculated by using the present partial safety factors is located between those of mild and steep bottom slopes of JPHA(2007). The proposed partial safety factors were inversely used to calculate the caisson width and reliability index of existing breakwaters. While the reliability indices of existing breakwaters designed by the deterministic method show a large variation, those designed by the partial safety factor method show a small variation. This indicates that the partial safety factor method allows a consistent design for given target probability of failure.

• Journal of the Korea Safety Management & Science
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• v.13 no.1
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• pp.31-39
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• 2011

In this study, supervision resides fire mission against problems associated with case studies and surveys done through the side of the field work, technical personnel, fire management, including fire code aspects classified into three kinds of items dealt with the issue. Started at the scene of the problem in terms of performance, the issue of the construction process, mainly dealt with the issue at the time of completion. Fire management side, supervisor of technical personnel, human resources management issues, contract issues, fire code level, the frequent revisions of fire regulations, supervision, processing delays of the resulting report, the problem resides with the expansion of Fire Supervision target was mentioned. Finally, the target for each hierarchical supervision, and resident supervisor of the need for supervision of work performance test was carried out by the correlation.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1525-1538
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• 2008

Currently, it has been a fashion to include RAMS of rolling stock in the order for purchasing the rolling stock. However, it's only to suggest a qualitative value or an ideal target without giving or demonstrating actual RAMS target, with only demonstrating passive RAMS by the data provided by the manufacturer. In the case of KTX project of 100 cars of KTX-II contracted in June 2006, their target has been suggested from the previous RAMS application standard and it aimed to achieve the reliability level of equivalent high speed rolling stock. Afterward, as actual KTX-II RAMS Plan and RAMS Demonstration Plan has been prepared and approved, it has been the first problem to secure the reliability and safety in order to introduce the new high speed rolling stock(KTX-II) successfully and we actually tried to apply overseas RAMS standard, KTX samples, electric railcar MTRC and rolling stock samples. This Report was dealt world trends of Railway RAMS standard, KTX-II RAMS Specifications, the present condition of KTX-II RAMS performance and development a way of KTX-II RAMS, We hope the "KTX-II RAMS Application Standard for Safety of Passenger Transportation Service" is served as an opportunity for the basic research for establishing and demonstrating RAMS target of components or parts composing the rolling stock system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.3
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• pp.217-223
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• 2017

In order to assess risk as a basic step for securing safety, it requires to select risk factors and determine the frequency and the severity of the consequence of each risk factor. This research adopted common risk factors among well-known maritime risk assessment models, and proposed objective criteria to gauge the risk level of each risk factor. The starting points of risk evolution were chosen for criteria according to related studies and seafarers' experience. The rate of risk appearance over the criteria is named as the incidence of risk factor. Therefore, the total risk level is expressed as the combination of incidence of each risk factor and severity. This quantitative method would be applied to measuring and comparing the risk level of target maritime zones, and it would also be useful to survey which risk factor be focused for reducing the total risk of a certain maritime zone.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.321-326
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• 2010

Government evaluate annually a performance of government's R&D(Research & Development) and decide a budget and progress. So, a performance target setting of R&D is very important at the planning, The basic performance target setting of railroad R&D is clear. However, a scientific and technological performance target setting of railroad R&D is very difficult and a reasonable level of it can not be judged. Therefore, this study will suggest a solution for a scientific and technological performance target setting of railroad R&D through regression analysis of successfully finished railroad R&D, after judging a reasonability of a scientific and technological performance through comparing railroad R&D with the other R&D.

• Journal of Industrial Technology
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• v.28 no.B
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• pp.149-156
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• 2008

A reliability model of Level II AFDA is developed to analyze the stability of armor units on the sloped coastal structures. Additionally, the partial safety factors of random variables related to armor units can be straightforwardly evaluated by applying the inverse-reliability method in which influence coefficients and uncertainties of random variables, and target probability of failure are combined directly. In particular, a design equation for armor units is derived in terms of the same criteria as deterministic design method in order to apply the reliability-based design method of Level I without some understanding to the reliability analysis. Finally, it is confirmed that several results redesigned by the reliability-based design method of Level I have satisfactorily agreement with results of CEM as well as those of Level II AFDA.