• Nuclear Engineering and Technology
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• v.23 no.2
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• pp.174-182
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• 1991

Effects of human error relevant to the periodic test are incorporated in the evaluations of the unavailability and optimal test interval of a safety system. Two types of possible human error with respect to the test and maintenance are considered. One is the possibility that a good safety system is inadvertently left in a bad state after test（Type A human error) and the other is the possibility that a bad safety system is undetected upon the test（Type B human error). An event tree model is developed for the steady-state unavailability of a safety system in order to determine the effects of human errors on the system unavailability and the optimal test interval. A reliability analysis of the Safety Injection System (SIS) was peformed to evaluate the effects of human error on the SIS unavailability. Results of various sensitivity analyses show that ; (1) the steady-state unavailability of the safety system increases as the probabilities of both types of human error increase and it is far more sensitive to Type A human error, (2) the optimal test interval increases slightly as the probability of Type A human error increases but it decreases as the probability of Type B human error increases, and (3) provided that the test interval of the safety injction pump is kept unchanged, the unavailability of SIS increases significantly as the probability of Type A human error increases but slightly as the probability of Type B human error increases. Therefore, to obtain the realistic result of reliability analysis, one should take shorter test interval (not optimal test interval) so that the unavailability of SIS can be maintained at the same level irrespective of human error. Since Type A human error during test & maintenance influeces greatly on the system unavailability, special efforts to reduce the possibility of Type A human error are essential in the course of test & maintenance.

• Journal of Korea Multimedia Society
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• v.14 no.7
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• pp.940-948
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• 2011

In this paper, we design and implement a task scheduler that considers real-time and fault tolerance in embedded system with a single processor. We propose a method how it can meet the deadlines of periodic tasks using RMS and complete the execution of aperiodic tasks by calculating surplus times from a periodic task set. And we describe a method how to recover of a transient fault task by managing backup time. We propose an important level of periodic tasks that can control the response time of periodic and aperiodic tasks. Finally, we analyse and evaluate the proposed methods by simulation.

• Journal of Internet Computing and Services
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• v.5 no.3
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• pp.35-43
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• 2004

In packet switching using multistage interconnection networks (MIN's), it is generally assumed that the packet movements successively propagate from the last stage to the first stage in one network cycle. However, Ding and Bhuyan has shown that the network performance can be significantly improved if the packet movements are confined within each pair of adjacent stages using small clock cycles. In this paper, an analytical model for evaluating the performance of input-buffered MlN's employing this network cycle approach is proposed, The effectiveness of the proposed model is confirmed by comparing results from the simulation as well as from Ding and Bhuyan model.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.1
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• pp.24-34
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• 1997

To find the causes of the downtime problems in Pohang New Harbor, extensive field measurements of short- and long-period waves for 1.5 months and their analyses were made taking into account of wind and downtime records. Measured wave height ratios inside the harbor are appeared to be slightly larger than predicted ones using numerical methods in the previous studies. It is shown that the major causes of the downtime are the wind wave (or swell) higher than loading criteria and also swell with even smaller wave height but longer period(more than 10 sec). Waves of long-period components[0(min)] were recorded as 20 cm high in case of dominant seiche phenomena but they might not be related with the downtime problems.

• Journal of the International Relations & Interdisciplinary Education
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• v.1 no.2
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• pp.31-47
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• 2021

This study intends to examine the indicators of Korean medicine education that are directly required in the field, in the process of developing and rationalizing the second cycle of evaluation and accreditation standards for the Colleges of Korean medicine and present indicators to the Korean medicine education community. To this end, we conducted the Delphi survey on six Korean medicine education experts, and the second cycle evaluation and accreditation standards were developed after verifying the validity of the contents and through a public hearing on three experts. Based on the research results of this study, we make the following suggestions: First, the support of Korean medical education institutions should be considered. The Korean medical education institution operates the Korean medicine hospital under each institution's name. Thus, criteria for evaluation shall be considered according to the number of beds and the support of schools. Second, for the second cycle of evaluation, all six members of the evaluation committee were professors of Korean medicine; however, in the future, each group of the evaluation committee needs to be composed of an external curriculum and evaluation experts to seek the evaluation focusing on education. Third, it is necessary to include curriculum and evaluation experts in the development stage of education programs and institutional evaluation and accreditation standards. Fourth, the experts of the curriculum should be included as the members of the curriculum development team of the College of Korean Medicine. This study is meaningful as a study to improve the quality of Korean medicine education.

• Journal of the Earthquake Engineering Society of Korea
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• v.9 no.4 s.44
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• pp.43-54
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• 2005

This paper presents cost-effectiveness evaluation of semi-active control system for cable-stayed bridge under earthquake excitations with various magnitudes and frequency contents. Semi-active control system, which is operated by using Bi-stale control method on the basis of linear quadratic Gaussian (LQG) optimal controller, is designed for the benchmark control problem proposed by Dyke et at. The cost-effectiveness of the proposed control system is defined by the ratio of life-cycle costs between a bridge structure with shock transmission units and a bridge structure with the semi-active control devices. The simulated results show that the damper cost has little influence on the cost-effectiveness of the semi-active control system while the cost-effectiveness is quite sensitive to the damage cost induced by the bridge failure. It is also found that the semi-active control system guarantees relatively high cost-effectiveness for the cable-stayed bridge subject to the ground motions in the regions of moderate seismicity with soft soil condition and strong seismicity with stiff soil condition.

• Korean Journal of Construction Engineering and Management
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• v.6 no.4 s.26
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• pp.164-171
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• 2005

The importance of the life cycle cost analysis(LCCA) for apartment housing remodeling projects has been fully recognized over the last decade. Accordingly theoretical models, guidelines, and supporting software systems were developed for the life cycle cost analysis of apartment housing remodeling systems. However, the level of consensus on LCCA results is still low due to the lack of reliable data on remodeling activities for safety diagnosis. in order to predict the reliability based LCCA of the given case, suggested the remodeling strategies level after reviewing other related materials. Apply the real information of the economic index. And based on such analytical measures, remodeling and operation cost and LCC in remodeling strategies level have been predicted; suggests the basic information about remodeling interventions level for the apartment housing. The LCC analysis models and the fuzzy logic based safety assessment presented in this study can greatly contribute to the value-oriented design alternative selection, estimation of the economic analysis, and the allocation of budget for apartm.

• Journal of the Korean Society of Safety
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• v.26 no.3
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• pp.52-58
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• 2011

The earthquake characteristic assessment of social overhead facilities would be an important examination issue for seismic capacity enhancement. This study is intended to reasonably evaluate the structural behavior of longperiod frame structures considering near-fault and far-fault earthquake characteristics. Elastic/inelastic time history analyses were performd by selecting the objective structure which can precisely reflect the effect of input ground motion. Based on the result of numerical analysis, we have investigated response aspects of shear force, moment, acceleration and displacement according to earthquake characteristics. Moreover, in order to understand the inelastic behavior of the objective structure, we have analyzed and compared collapse modes by considering the occurrence process of plastic hinges. The outcome of this research is expected to provide the basic information for the seismic safety assessment of long-period frame structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.4
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• pp.112-118
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• 2013

The selection of appropriate ground motions and reasonable modification are becoming increasingly critical in reliable prediction on seismic performance of structures. A widely used amplitude scaling approach is not sufficient for robust structural evaluation considering a site specific seismic hazard because only one spectral value is matched to the design spectrum typically at the structural fundamental period. Hence alternative approaches for ground motion selection and modifications have been suggested. However, there is no means to evaluate such methodologies yet. In this study, it is focused to describe the main questions resided in the amplitude scaling approach and to propose a regression model for structural damage as point of comparison. Spectrum compatible approach whose resulting spectrum matches the design spectrum at the entire range of the structural period is considered as alternative to be compared to the amplitude scaling approach. The design spectrum is generated according to ASCE7-05.

• Journal of Digital Convergence
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• v.19 no.5
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• pp.207-214
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• 2021

Humans are environmentally exposed to various electromagnetic fields, but the evaluation of the harmfulness of electromagnetic field and the development of a system therefor are still incomplete. We aimed to develop a system for evaluating biohazard against electromagnetic fields, and to determine biohazard through the system. An extremely-low frequency magnetic field generator was designed and manufactured, and the output reliability of the device was verified. Using this device, the effect on the formation of cellular stress-granules and the cell cycle progression of cells exposed to high magnetic fields of 6 mT and 60 Hz was confirmed. As a result, exposure to high magnetic fields of 6 hr, 12 hr and 36 hr did not affect the formation of cell stress-induced granules and the cell division cycle. These results are an important basis for the determination of biohazard to the extremely-low frequency high magnetic field.