• Journal of Ocean Engineering and Technology
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• v.19 no.6 s.67
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• pp.64-71
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• 2005

The welding methods have been applied to the most structural products used in the automobile, ship construction, and construction. The structure steel must have sufficient strength of structure; However, the mechanical properties of the welded part changes when it is welded. Therefore, the stability or life of the structure may be affected by the changed mechanical properties. The mechanical properties of the welded part must be examined in order to ensure the safety of structure. In this research, the SS400 steel and the STS304 steel were used to estimate the mechanical properties of the HAZ by weld thermal cycle simulation. In this study, the materials were used to examine the weld thermal cycle simulation characteristic, under two conditions: the drawing with diameter of $\Phi$10 and the residual stress removal treatment. To examine the mechanical properties by the weld thermal cycle simulation, the tensile test was carried out in room temperature. The crosshead speed was lmm/min.

• Journal of Applied Reliability
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• v.15 no.1
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• pp.27-32
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• 2015

Functional safety is part of the overall safety relating to the equipment under control (EUC) and the EUC control system that depends on the correct functioning of the electrical/electronic/programmable electronic (E/E/PE) safety-related systems. Since the complexity of the medical equipment is increased, manufactures have to obtain functional safety as well as basic safety. This study proposes a perspective for applying functional safety to medical equipment. The research is carried out with respect to overall safety life-cycle of functional safety and essential performance of the medical equipment. The relationship between functional safety and essential performance is identified centered on the safety function. The essential performance using E/E/PE systems is defined as a safety function of functional safety. This approach is applied to a ultrasound imaging system as a case study.

• Journal of the Korea Safety Management & Science
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• v.10 no.1
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• pp.215-224
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• 2008

Recently, product life-cycles are shortening faster than ever before, and companies with a suggestion system are in better position to overcome this shortening life-cycle and thus promote customer satisfaction. Suggestion systems, however, are not actively utilized on the production floors in many firms. This study showed that small-sized and medium-sized firms where a suggestion system is properly functioning by a strong will of top management are not many in Gangwon-do area. In considerable number of companies, a suggestion system is informally and spontaneously applied by the workers on the production floors not by company-wide systems. A suggestion system is required as a means of creating future value-added and it is a matter of course that the role of top management, together with middle-class managements' influence is quite important in the course of the successful application of it. A suggestion system, to be successful, calls not only individual efforts but also positive corporate cultures.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.9-18
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• 2019

This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow's tractive force as well as the torque from the engine output shaft on the rear axle under various working speeds (L4, M1, M2, M3). We chose a Korean test site of Seomyeon, Chuncheon with sandy soil texture, as determined using the USDA method. We constructed the load spectrum for torque and tractive force using measured data and derived the fatigue life of the plowshare from a stress-cycle (S-N) curve of the plow material. Our results show that the M3 gear maximizes the driving shaft torque loads and, applying the tractive force load spectrum, creates a cumulative damage sum of $4.14{\times}10^{-5}$. Considering sampling time, we estimate a fatigue life of 805 hours while using the M3 gear. When using the other working speeds, however, all of the stress levels fell within the endurance limits and, therefore, our model predicts infinite plowshare lifetimes. For this analysis, we used a yield strength of 1,079 MPa for the plowshare and static safety factors, analyzed using the maximum stress, between 6.83 and 8.63 under each working speed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.147-148
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• 2019

Long-life housing should be durable enough to maintain structural safety even after long-term use by applying a durable structural system. Also, the residence space can be repaired according to the life cycle of the resident, and the space can be easily changed. The purpose of this study is to propose a plan which can increase the variability of unit space of long - lived houses in terms of architectural planning. We propose a new plan that can embody flexibility and ease of repair through the design of long life.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.141-150
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• 2004

Recently, it is really concerned about corrosion and aging of reinforced concrete bridges. Corrosional steel reinforcing in concrete affects not only safety of bridges structure but also bending strength of reinforced concrete's member. Rate of corrosion, characteristic of bending strength, and economical evaluation aren't clear in reinforced concrete, considering performance evaluation. The purpose of study is as follows. It studies about ability of resistance's strength and cost of life cycle according to reduction of steel reinforcing's corrosion. Moreover, it shows calculating formula of bending strength with corrosion of current rate and exactly evaluates about the rest life at corrosional reinforced concrete bridges.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.118-120
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• 1996

We've been reported recently that increase of installing big power converting equipment which makes harmonics result in damage on transformer for incoming and load. Specially, harmonics that cause overheat and aging is severer in cast-resin transformer a kind of dr type than in oil one. The goal of this paper is to prove the process for aging of transformer that result from harmonics in according to both of theory and actual measurement on site. And we introduce diagnostic methods to estimate aging condition of cast-resin transformer in accordance with simulation.

• International Journal of Concrete Structures and Materials
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• v.3 no.2
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• pp.103-110
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• 2009

Concrete carbonation is a cause of problems in concrete structures, so it needs to be estimated. And concrete cover is designed to protect structures from this damaging. Usually the cover thickness is considered based on the limit states design codes in which the important target is the reliability safety index. However, it is not clear that whether the safety index determined is optimal or not with respect to the cost. The codes are mainly proceeded quantitatively (i.e. making a safe structure) while the economic aspects are only considered qualitatively. So the reliability-based design considering life cycle cost (LCC) is called for, and here the focus is on the advanced analysis solution to optimize the reliability safety regarding LCC.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.683-688
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• 2007

The importance of reliability and safety, recently, shows a tendency to increases in railway system constructions and projects. At the point of view of safety, especially, the railway authority proposes an establishment of the safety case that is the documented demonstration that products comply with the specific safety requirements in railway industry. In case of reliability activities, there is no systematic documented demonstration in the railway industry. At this circumstance, this study presents the establishment of Reliability, Availability and Maintainability Case for railway system based on the MoD(Ministry of Defence) 00-42. This RAM Case will support that systems and products produced from suppliers or manufacturers meet the specific RAM requirements during the system life cycle(i.e, from design to operation & maintenance) through systematic process and evidences. Also, it is expected that railway system operations will be managed and supported from reliability activities in accordance with RAM Case.

• Journal of Sensor Science and Technology
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• v.24 no.5
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• pp.326-330
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• 2015

The recent development of Sensor technology has broadened its applications to many fields of industry including railroad. The sensor technology enables the railroad system to monitor and control. This paper suggests the sensor based system design for evaluating and improving the reliability and safety of the ICT system. For this purpose, the reliability and the level of safety integrity of a general gateway have been predicted quantitatively and the supplementary design has been proposed for RAMS improvement. RAMS requirements for each life cycle stipulated in IEC 62278. RAMS activity is capable of producing significant and effective reductions in operation costs and time.