• Journal of the Korean Society of Safety
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• v.31 no.5
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• pp.95-101
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• 2016

This study proposes a multi-scale dynamic system reliability analysis of control system as a method of quantitative evaluation of its performance in probabilistic terms. In this second paper, we discuss the control effect of the viscous damper on the seismic performance of the structure-level failure. Since the failure of one structural member does not necessarily cause the collapse of the structural system, we need to consider a set of failure scenarios of the structural system and compute the sum of the failure probabilities of the failure scenarios where the statistical dependence between the failure scenarios should be taken into account. Therefore, this computation requires additional system reliability analysis. As a result, the proposed approach takes a hierarchial framework where the failure probability of a structural member is computed using a lower-scale system reliability with the union set of time-sequential member failures and their statistical dependence, and the failure probability of the structural system is again computed using a higher-scale system reliability with the member failure probabilities obtained by the lower-scale system reliability and their statistical dependence. Numerical results demonstrate that the proposed approach can provide an accurate and stable reliability assessment of the control performance of the viscous damper system on the system failure. Also, the parametric study of damper capacity on the seismic performance has been performed to demonstrate the applicability of the proposed approach through the probabilistic assessment of the seismic performance improvement of the damper system.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.116-122
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• 2014

This study proposes a system reliability analysis of rack storage facilities subjected to forklift colliding events. The proposed system reliability analysis consists of two steps: the first step is to identify dominant failure modes that most contribute to the failure of the whole rack facilities, and the second step is to evaluate the system failure probability. In the first step, dominant failure modes are identified by using a simulation-based selective searching technique where the contribution of a failure mode to the system failure is roughly estimated based on the distance from the origin in the space of the random variables. In the second step, the multi-scale system reliability method is used to compute the system reliability where the first-order reliability method (FORM) is initially used to evaluate the component failure probability (failure probability of one member), and then the probabilities of the identified failure modes and their statistical dependence are evaluated, which is called as the lower-scale reliability analysis. Since the system failure probability is comprised of the probabilities of the failure modes, a higher-scale reliability analysis is performed again based on the results of the lower-scale analyses, and the system failure probability is finally evaluated. The illustrative example demonstrates the results of the system reliability analysis of the rack storage facilities subjected to forklift impact loadings. The numerical efficiency and accuracy of the approach are compared with the Monte Carlo simulations. The results show that the proposed two-step approach is able to provide accurate reliability assessment as well as significant saving of computational time. The results of the identified failure modes additionally let us know the most-critical members and their failure sequence under the complicated configuration of the member connections.

• Child Health Nursing Research
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• v.8 no.3
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• pp.291-301
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• 2002

This study was performed to develop a scale of maternal conflict based on already established scales and the literature review. The major purpose of this study was to develop a scale of which contains difficulties which mother can feel to rearing her child and can be applied to mothers at home or employed mothers. 68 items were developed. For content validity test, the items were examined by 7 experts panel with Likert 4 scale. The 39 items were selected as high validity from 86% of the experts. The item number of each area and the misunderstanding words were corrected by advices of experts. 10 mothers again examined 39 items in order to correct the misunderstanding words and the long sentences. For reliability and factor analysis of 39 items, 496 mothers participated. 34 items were chosen because 5 items that corrected item-total correlation coefficient were lower than 0.2 were excluded by the result of reliability analysis. Factor analysis was done with 34items. 6 factors were classified higher than eigen value 1.0, 28 items were chosen because 6 items that factor loadings were lower than 0.4 were excluded. These factors were named as employment and caring for child(6 items), child education(5 items), support system for caring for child(4 items), interaction with mother and child(4 items), view of maternal role(5 items) and me as human being(4 items). Reliability analysis was done with 28 items. 1 item(36 number of factor 1) was excluded because corrected item-total correlation coefficient were lower than 0.2. Therefore, 27 items were chosen. Maternal Conflict Scale was contained 27 items. The corrected item-total correlation coefficient of 27 items were ranged from .2345 to .5240 and Cronbach alpha coefficient of those was .8207 by the results of reliability analysis. It can be evaluated that this scale had a high validity and reliability because of passing through an objective process of test.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.479-486
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• 2012

Runoff characteristics of pollutant loads of the lower Han River was studied before full implementation of Total Pollution Load Management System(TPLMS). Magnitude of macroscopic(annual) fluctuation was in the order of Namhan River > Han River > Bukhan River, gross weight TP > gross weight TN > gross weight BOD, gross weight deviation > concentration deviation. Flux variation was higher than that of concentration. Microscopic(weekly) fluctuation showed similar pattern to macroscopic scale. TP showed the highest deviation resulting in the lowest reliability. 60% of annual flux passed during summer 3months resulting in 43-46% pass of gross weight at the lower Han River. Strong correlation was found between flux and gross weight especially in gross weight TN. Gross weight pollution increased as high as 400% while passing Seoul area due to the concentration. The deviation from moving average increased during summer season in the gross weight TP and BOD. Seasonal tendency was confirmed especially in gross weight TN and TP using autocorrelation function.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.4
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• pp.348-358
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• 2003

According to Electricity Acceleration Law of Rural Area recently, the needs for replacement of a small scale diesel power generation facility which supplied electricity to 10-50 households Remote Islands has been revealed due to high operating and maintenance cost of Diesel Power Generation. Optimization of electric power system for Small Remote Islands must be made considering the economics, reliability and stability as power sources and estimation of total construction cost of those power stations. For its purpose, an assessment of power generation options such as Photovoltaic, Fuel cell, Wind-hybrid was implemented, economic evaluation of power supply shows the Photovoltaic, Fuel Cell for few household's islands and Diesel, Wind-hybrid for more inhabited islands. Power supplied by Diesel shows the best response to increasing electric demand and system reliability even with its lower economic value. Those who are in charge of power planning have to pay attention to system reliability, stability and operating characteristics of candidate's power supply besides its economics.

• Journal of Aerospace System Engineering
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• v.18 no.2
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• pp.21-28
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• 2024

In light of the rapid development of the space industry, there has been increased attention on small satellites. These satellites rely on components that are considered to have lower reliability compared to larger-scale satellites. As a result, predicting reliability becomes even more crucial in this context. Therefore, this study aims to compare three reliability prediction techniques: MIL-HDBK-217F, RiAC-HDBK-217Plus, and FIDES. The goal is to determine a suitable reliability standard specifically for nano-satellites. Furthermore, we have refined the quality assurance factors of the manufacturing company. These factors have been adjusted to be applicable across various industrial sectors, with a particular focus on the selected FIDES prediction standard. This approach ensures that the scoring system accurately reflects the suitability for the aerospace industry. Finally, by implementing this refined system, we confirm the impact of the manufacturer's quality assurance level on the total failure rate.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1128-1134
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• 2016

Demand response provides customer load reductions based on high market prices or system reliability conditions. One type of demand response, price-based program, induces customers to respond to changes in product rates. However, there are large-scale general and industrial customers that have difficulty changing their energy consumption patterns, even with rate changes, due to their electricity demands being commercial and industrial. This study proposes an in-house pricing model for large-scale general and industrial customers, particularly those with multiple business facilities, for self-regulating demand-side management and cost reduction. The in-house pricing model charges higher rates to customers with lower load factors by employing peak to off-peak ratios in order to reduce maximum demand at each facility. The proposed scheme has been applied to real world and its benefits are demonstrated through an example.

• Physical Therapy Korea
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• v.30 no.4
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• pp.306-313
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• 2023

Background: As social problems due to the acceleration of the aging era and the increase in the elderly population are becoming serious, virtual reality (VR)-based healthcare is emerging as an approach for preventing and managing health issues. Objects: This study used validity and reliability analyses to examine the clinical efficacy that is, the clinical value and usability of a novel VR cognitive evaluation system index that we developed. Methods: We developed a VR cognitive evaluation system based on motion recognition analysis evaluation for individuals aged 65 to 85. After conducting the Korean version of the Mini-Mental State Exam (K-MMSE) cognitive evaluation, the evaluation score was verified through correlation analysis in the VR cognitive evaluation system. To verify the construct validity of the two groups, the Global Deterioration Scale (GDS) grades were categorized into a normal cognitive group (GDS grade 1) and a cognitive impairment group (GDS grades 2 and 3). The data were measured twice to determine the reliability between the two measurements and assess the stability and clinical value of the evaluation system. Results: Our evaluation system had a high correlation of 0.85 with the widely used K-MMSE cognitive evaluation. The system had strong criterion-related validity at the 95% confidence interval. Compared to the average score of GDS grade 1 in the VR cognitive evaluation system, the average score of GDS grades 2 and 3 in the VR cognitive evaluation system was statistically significantly lower while also having strong construct validity at the 95% confidence interval. To measure the reliability of the VR cognitive evaluation system, tests-retests were conducted using the intraclass correlation coefficient (3,1), which equaled 0.923 and was statistically significant. Conclusion: The VR cognitive evaluation system we developed is a valid and reliable clinical tool to distinguish between normal cognitive status and mild cognitive impairment.

• The Journal of Korean Medicine
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• v.17 no.1 s.31
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• pp.48-83
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• 1996

Our conclusions for function evaluation tools of Stroke patients are as follows. 1. Evaluating tools of Activities of Daily Living, Katz Index, Barthel Index, Modified Barthel Index have high validity and reliability because of ease of measuring, high accuracy, consistency, sensitivity and sufficient stastistics, but they mainly measure motor function except sense, mentation, language, and social conception. Therefore cerebrovascular disease and brain injury in trauma patients with lacked acknowledgement and sensation, we are not able to apply these tools. 2. PULSES Profile is a useful scale for measuring the patient's over-all status, upper and lower limb functions, sensory components, excretary functions, and intellectual and emotional adaptabilities. It is recognized as a good, useful tool to evaluate patient's whole function. 3. Motor Assessment Scale was designed to measure the progress of stroke patients. The scale was supplemented with upper arm function items. We believe that the Motor Assessment Scale could be a useful evaluation tool with inter-rater reliability ,test-retest reliability. 4. The existing evaluation tools, Katz Index, Barthel Index, Modified Barthel Index, PULSES Profile, Motor Assessment Scale, mainly measured the rehabilitational motor function of sequela of cerebrovascular patients. On the other hand CNS & INH stroke scale can measure cerebrovascular disease patient's neurologic deficits and over-all stautus, which are recognition ability, speech status, motor function, sensory function, activities of daily living. Those scales have been recognized as useful tools to measure function of cerebrovascular disease patients and have increased in use. 5. Every function evaluation tool was recognized to have some validity and inter-rater, test-retest reliability in items of each evaluation tool and total scores of each evaluation tools, but it is thought that none of these scales have been fully validated and proved reliable. Therefore afterward, the development of a highly reliable rating system may best be accomplished by a careful comparison of several tools, using the same patients and the same observers in order to choose the most reliable items from each. 6. Ideal evaluation tools must have the following conditions; (1) It should show the objective functional statues at the same time. (2) It should be repeated consecutively to know changed function status. (3) It should be easy to observe the treatment program. (4) It should have the same result with another rater to help rater exchange information with treatment team members. (5) It should be practical and simple. (6) The patient should not suffer from the observer.

• Proceedings of the KSRS Conference
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• v.2
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• pp.631-634
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• 2006

Three main important sources for establishing GIS are the orthomap in scale 1:5 000 with Ground Sampling Distance of 0,5m; DEM/DTM data with height error of ${\pm}$1,0m and topographic map in scale 1: 10 000. The new era with Very High Resolution Satellite (VHRS) images as IKONOS, QuickBird, EROS, OrbView and other ones having Ground Sampling Distance (GSD) even lower than 1m has been in potential for producing orthomap in large scale 1:5 000, to update existing maps, to compile general-purpose or thematic maps and for GIS. The accuracy of orthomap generated from VHRS image affects strongly on GIS reliability. Nevertheless, orthomap accuracy taken from VHRS image is at first dependent on chosen sensor geometrical models. This paper presents, at fist, theoretical basic of the Rational Polynomial Coefficient (RPC) model installed in the commercial ImageStation Systems, realized for orthorectifying VHRS images. The RPC model of VHRS image is a replacement camera mode that represents the indirect relation between terrain and its image acquired on the flight orbit. At the end of this paper the practical accuracies of IKONOS and QuickBird image orthorectified by RPC model on Canadian PCI Geomatica System have been presented. They are important indication for practical application of producing digital orthomaps.