• Journal of Applied Reliability
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• v.14 no.1
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• pp.81-91
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• 2014

The IEC 61508 standard was established to specify the functional safety of E/E/PE safety-related systems. Safety life cycle to provide the framework and direction for the application of IEC 61508 is included in this standard. In this paper, we describe overviews, objects, scopes, requirements and activities of each phase in safety life cycle. In addition, we introduce safety integrity level(SIL) which is used for verifying the safety integrity requirements of E/E/PE system and perform a case study to estimate hardware SIL by FMEDA. The SIL is evaluated by two criteria. One of them is the architectural constraints which restrict the maximum SIL by combination of SFF and HFT. The other is the probability of failure which is classified into PFD and PFH based on frequency of demand and calculated by safe or dangerous failure rates.

• Journal of the Korea Safety Management & Science
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• v.10 no.1
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• pp.91-105
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• 2008

Nowadays, circulation industry is taking charge of important role in improvement of competitive power on the manufacturing industry and public welfare increase of consumer, price stabilization, employment creation and so on. A lot of research have been progressing for formation of total circulation complex, but decision making for selection of location on some facility is only calculated the optimum value when correct data values are inserted. However, a lot of decision making is accomplished in situation that have little knowledge of objective and constraints and as real world is also evaluated inclusive of analyst's subjectivity about variable, indefinite and fuzzy part, so it is decreasing a reliability on evaluation result and complicating objective evaluation on various effect and negative impact. Accordingly, from under like this situation, this study is to develop location decision model of circulation complex using fuzzy theory from the intention for the most reasonable decision making in fuzzy situation based on decision making problem on conventional location and size decision that did to be satisfactory constraints necessarily.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.7
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• pp.602-610
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• 2000

In communication networks used in safety-critical systems such as control systems in nuclear power plants there exist three types of data traffic : urgent or asynchronous hard real-time data hard real-time periodic data and soft real-time periodic data. it is necessary to allocate a suitable bandwidth to each data traffic in order to meet their real-time constraints. This paper proposes a method to meet the real-time constraints for the three types of data traffic simultaneously under a timer-controlled token bus protocol or the IEEE 802.4 token bus protocol and verifies the validity of the presented method by an example. This paper derives the proper region of the high priority token hold time and the target token rotation time for each station within which the real-time constraints for the three types of data traffic are met, Since the scheduling of the data traffic may reduce the possibility of the abrupt increase of the network load this paper proposes a brief heuristic method to make a scheduling table to satisfy their real-time constraints.

• Journal of Radiation Industry
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• v.17 no.1
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• pp.61-67
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• 2023

A Study on the Introduction of Dose Constraints for Occupational Exposures: Focusing on Experts' Opinions by Field of Radiation Industry. The International Commission on Radiological Protection suggests Justification, Optimization, and Dose Limits as the three principles of radiological protection, among which, as a means of protection optimization, ICRP 103 recommends to set dose constraints. In this study, opinions are collected from experts in each category of radiation industries for stakeholder participation to qualify dose constraints. A guidance and questionnaire for analyzing the dose constraints have been developed for their collection, and opinions were collected from radiation protection experts in selected categories. 20 out of 22 experts, consisted with 91%, have assessed the dose constraints setting is necessary, and 2 experts, consisted with 9%, assessed it is unnecessary. The average of dose constraint presented by experts for RI production institutions is to be the highest level of 15.3 mSv, and light-water reactors (14.6 mSv), non-destructive inspection (14.4 mSv), heavy-water reactor and medical institutes (13.9mSv) is to be above the overall average dose constraint. In case of public institutions, the average dose constraint is to be 8.6mSv, and research institutions (8.8mSv), educational institutions (9.6 mSv), waste disposal sites (9.7 mSv), and general industries (10.6 mSv) are resulted to below the overall average dose constraint. As for the means of setting dose constraints, 8 experts out of 22 suggested setting dose constraints for each specific industry or task. And, 5 experts especially suggest setting dose constraints for the specific groups with relatively high exposure, such as workers with above the record levels. As a countermeasure for workers who exceed the dose constraints, 15 experts out of 22 expressed that the cause analyses for them and preparation for a plan of reducing them are necessary.

• 시스템엔지니어링워크숍
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• s.4
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• pp.151-154
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• 2004

This paper presents the general system theory and its applications to the safety analysis method that is a recent trend over the traditional event-driven model. This new model is known as STAMP(Systems Theory Accident Modeling and Process)proposed by Nancy G. Leveson in MIT. The new model has benefits of systemic approaches concerning the system safety as a whole including the context it is in, its stimulants and outcomes, and its parts as well as the relationships among them in a holistic manner. The method consists of a hierarchical control structure, a process model, and the safety constraints governing the control. This paper demonstrates an example the contrasts the differences between the approaches of STAMP and the traditional safety models.

• Journal of the Korea Safety Management & Science
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• v.3 no.3
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• pp.77-86
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• 2001

An operational strategy for inventory control on finished goods in the distribution system has been given attention to many enterprises and many studies regarding this field have been done and is also on-going currently. Many of these studies represented a large scale distribution network with a unified formulation by using defined symbols. These methods have provided the systematic approach of the distribution network but they are impossible to applying the reality system due to not considering the service rate of demand and treating the shortage of inventory. In order to overcome these unrealistic problems, the novel safety stock policy of responding to customers' inventory distribution network is suggested. this paper explores the transportation between Central Distribution Center(CDC) and Regional Distribution Center(RDC). Especially, the relation of transportation cost between CDC and RDC and cost of inventory control according to safety inventory with service level are emphasized. We could obtain the good results of this study by determining the optimal safety stock considering the various variables and constraints.

• Journal of the Korean Society of Systems Engineering
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• v.1 no.1
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• pp.20-25
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• 2005

This paper presents the general system theory and its applications to the safety analysis method that is a recent trend over the traditional event-driven model. This new model is known as STAMP(Systems Theory Accident Modeling and Process) proposed by Nancy G. Leveson in MIT. The new model has benefits o f systemic approaches concerning the system safety as a whole including the context it is in, its stimulants and outcomes, and its parts as well as the relationships among them in a holistic manner. The method consists of a hierarchical control structure, a process model, and the safety constraints governing the control. This paper demonstrates an example that contrasts the differences between the approaches of STAMP and the traditional safety models.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.44-45
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• 2019

Tower cranes are essential equipments that play a key role in the overall process of large-scale construction projects, as well as high-rise apartments construction projects. Tower cranes hoist various loads near and over people, working in crowded environments, sometimes in overlapping work areas, and often under the constraints of time, budget, and labor. This work system further increases the safety risks of sites with inherently hazardous workplaces. The methodology of this research was based on a comprehensive inquiry of a team of experts, including safety managers and equipment managers of major construction companies and previous literature search. Due to the limited resources available to improve safety and prevent accidents, more attention should be paid to all parties involved in factors that have been evaluated to have a significant impact on site safety due to tower crane operations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.8 no.1
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• pp.161-167
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• 2002

This paper describes the types and features of amphibious ships which have been constructed and commissioned. The characteristics of hull form design also are studied. Design constraints due to general arrangement and the satisfaction of requirements are investigated. We represent the design concept of hull form based on the design data of the worldwide amphibious ships and our experiences.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.39-46
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• 1997

This study describes a computer aided design system on involute gear for power transmition. Input data for gear design are pressure angle $20^{\circ}$, transmitted power, gear volume, gear ratio, addendum ratio of rack, dedendum ratio of rack, edge radius of rack, allowable contact stress and allowable bending stress etc. Bending strength contact strength and scoring are considered as the design constraints. Method of optimization developed this study. The developed gear design system can design the optimized gear that minimize the number of pinion teeth with face tooth.