• Proceedings of the Korean Reliability Society Conference
• /
• 2006.05a
• /
• pp.158-164
• /
• 2006

The creep behavior of newly developed composite geogrids which consists of PET yarns sheathed in PP were evaluated using SIM. For the SIM procedure, three test parameters, the applied loads, temperature steps and number of ribs were investigated, The study confirmed that temperature steps of 10 and 14$^{\circ}C$ up to 80$^{\circ}C$ are applicable for composite geogrids due to the different transition temperatures between two materials. At applied loads of 40 and 50%, only primary creep state was measured, while secondary creep state appeared at the applied loads of 60%, The lifetimes of composite geogrids were estimated at each of loading level using statistical reliability analysis technique. The results show that the lifetimes longer than 100 years can be predicted within 16 hours. Therefore, SIM is very effective and economical accelerated creep test methods, especially for lifetime prediction. This gives guidelines for users to select the appropriate factor of safety against creep considering the field condition within shorter test times.

• Structural Engineering and Mechanics
• /
• v.27 no.1
• /
• pp.33-48
• /
• 2007

An Articulated tower is one of the compliant offshore structures connected to the sea-bed through a universal joint which is the most vulnerable location of the tower that sustains the randomly fluctuating shear stresses. The time history response of the bottom hinge shear is obtained and presented in the spectral form. The fatigue and fracture reliability assessment of the tower joint against randomly varying shear stresses have been carried out. Non-linear limit state functions are derived in terms of important random variables using S-N curve and fracture mechanics approaches. Advanced First Order Reliability Method is used for reliability assessment. Sensitivity analysis shows the influence of various variables on the hinge safety. Fatigue life estimation has been made using probabilistic approach.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.195-198
• /
• 2004

In recent, the Importance and necessity of some studies on reliability evaluation of grid comes from the recent black-out accidents occurred in the world. The quantity evaluation of transmission system reliability is very important under competitive electricity environment. Accurate probabilistic reliability evaluation depends on assessment of forced outage rate of elements, generators, transmission lines. This paper describes basic theory of relationship between outage rates and reliability evaluation for assessing FOR(forced outage rate) of elements of power system. In case study, FORs assessed and supplied from Canada Electricity Association is introduced and FORs assessed from using actual historical data from 1997 to 2002 for transmission lines of KEPCO system.

• Geomechanics and Engineering
• /
• v.2 no.1
• /
• pp.57-69
• /
• 2010

A major consideration in the design of tunnels in urban areas is the prediction of the ground movements and surface settlements associated with the tunneling operations. Excessive ground movements can damage adjacent building and utilities. In this paper, a neural network model is used to predict the maximum surface settlement, based on instrumented results from three separate EPB tunneling projects in Singapore. This paper demonstrates that by coupling the trained neural network model to a spreadsheet optimization technique, the reliability assessment of the settlement serviceability limit state can be carried out using the first-order reliability method. With this method, it is possible to carry out sensitivity studies to examine the effect of the level of uncertainty of each parameter uncertainty on the probability that the serviceability limit state has been exceeded.

• The Korean Journal of Emergency Medical Services
• /
• v.15 no.2
• /
• pp.67-84
• /
• 2011

Purpose: The aim of this study is to present the basic data for qualitative improvement of emergency care for emergency patient by paramedic in fire station by understanding the level of awareness and practice in prehospital and transfer step, and understanding the level of emergency care and improvement of clinical knowledge through hospital clinical training. Methods: The researchers explained the objective for 143 persons who completed hospital clinical training from June 2nd, 2006 to October 23rd, 2009 among paramedic in fire station. The questionnaire in this research consisted of 80 questions. In the reliability for the awareness of emergency patient assessment, cronbach's $\alpha$ was 0.95, and in the reliability for emergency care fulfillment, cronbach's $\alpha$ was 0.93. reliability for clinical knowledge improvement is cronbach's $\alpha=.95$, and reliability for emergency care fulfillment is cronbach's $\alpha=.82$. Collected data was analyzed through SPSS 18.0 statistics program for frequency, percentage, average, standard deviation, Paired t-test, t-test, Correlation Coefficient, and internal consistency reliability was analyzed by cronbach's $\alpha$. Results: 1) The paramedic awareness and practice difference for emergency patient is statistically signification for general patient assessment(t=14.159, p=.000), trauma patient assessment(t=11.288, p=.000), internal medicine patient assessment(t=10.898, p=.000), and it shows the level of practice is lower than the level of awareness. 2) The paramedic difference between the level of awareness and practice according to whether or not they have clinical career is not signification on awareness(t=3.119, p=.125), and is high on practice(t=3.119, p=.002). 3) The correlation between paramedic awareness and the level of practice shows positive correlation(r=.61, p=.000). The higher the awareness of emergency patient assessment is, the higher the level of practice is. 4) The difference between paramedic clinical knowledge improvement and the level of emergency care practice is statistically significant(t=3.351, p=.001). 5) 89.6%(128 persons) of paramedic replied hospital clinical training experiences are helpful for field activity. 92.3%(133 persons) replied they apply well for clinical knowledge learned during hospital clinical training and emergency care skills in the field. Conclusion: Paramedic in fire station must evaluate the patient's initial assessment and activate the transfer system to the emergency department. It is necessary to develop and implement the effective education program continuously. The education program should systemize currently operated hospital clinical training. emergency disease and symptoms emergency care method, and practice mainly skill education should be progressed. In the prehospital and transfer management, high quality of medical assessment is required to the emergency medical service system. Medical direction from the doctors can feedback the paramedic continuously and continuing education must be provided to the paramedic in fire station.

• Journal of The Korean Association For Science Education
• /
• v.25 no.2
• /
• pp.173-183
• /
• 2005

In this study, we questioned what assessment types and scoring methods of science performance assessment(SPA) were being used in middle and high school, and how much these SPA scores were reliable(generalizable). To answer these questions, SPA data obtained from the seven schools were classified according to assessment type and scoring method. Based upon this classification, we analyzed the reliability by applying generalizability theory. The result, from the classification of assessment type and scoring method, showed that SPA types of the seven schools were divided into two types: paper-pencil type and task type. Paper-pencil type included answer(content)-restricted essay-type test solely. Task type has two parts: process and outcome assessment. As the results of analyzing scoring methods of the seven schools, there were two cases in the way of scoring methods: one case is scoring all essay-type items and performance tasks by one teacher, the other is scoring assigned performance tasks by two teachers. But the case of scoring assigned essay-type items or the case of cross scoring by two or more teachers were not found. The findings of the reliability analysis are as follows: (1) Effect of essay-type item to SPA score was larger than that of performance task. (2) There was remarkable difference among the seven schools' interaction effect of person and rater in scoring performance tasks. (3) Most of generalizability(reliability) coefficients of SPA for the seven schools were smaller than the acceptable generalizability coefficient(0.80). Therefore, the population of statistical parameters such as number of item, task and rater, should be increased for approaching the acceptable generalizability level.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.6
• /
• pp.348-355
• /
• 2017

Human activities have resulted in soil pollution problems to us. Human and ecological risk assessment have been suggested as an efficient environmental management strategy for protecting human and ecosystems from soil pollution. However, Korean environmental policy is currently focused on human protection, and fundamental researches for ecology protection are required for institutional frameworks. In this study, we developed a schematic frame of Korean soil ecological risk assessment, and suggested the basic information for its application. This study suggested a soil ecological risk assessment scheme consisting of 4 steps for derivation of Predicted-No-Effect-Concentration (PNEC): 1) ecotoxicity data collection and reliability determination, 2) data standardization, 3) evaluation of data completeness for PNEC calculation, and 4) determination of ecological-risk. The reliability determination of ecotoxicity data was performed using Reliability Index (RI), and the classification of domestic species, acute/chronic, toxicity endpoint, and soil properties was used for data cataloging. The PNEC calculation methodology was determined as low-reliability, middle-reliability, and high-reliability according to their quantitative and qualitative levels of ecotoxicity data. This study would be the introductory plan research for establishment of Korean soil ecological risk assessment, and it can be a fundamental framework to further develop guidelines of Korean environmental regulation.

• Journal of Climate Change Research
• /
• v.2 no.3
• /
• pp.203-219
• /
• 2011

Greenhouse gas(GHG) inventories were reported recently in various fields. It, however, has been rarely to mention about the accuracy and reliability of the GHG inventory results. Some reliable assessment methods were introduced to judge the accuracy of the GHG inventory results. It is, hence, critical to develop an evaluation methodology. This project was designed 1) to develop evaluation methodology for reliability of inventory results by GHG-CAPSS, 2) to check the feasibility of the developed evaluation methodology as a result of applying this methodology to two emission sources: liquid fossil fuel and landfill, and 3) to construct the technical roadmap for future role of GHG-CAPSS. Qualitative and quantitative assessment methodologies were developed to check the reliability and accuracy of the inventory results. Qualitative assessment methodology was designed to evaluate the accuracy and reliability of estimation methods of GHG emissions from emission and sink sources, activity data, emission factor, and quality management schemes of inventory results. On the other hand, quantitative assessment methodology was based on the uncertainty assessment of emission results. According to the results of applying the above evaluation methodologies to two emission sources, those seem to be working properly. However, it is necessary to develop source-specific rating systems because emission and sink sources exhibit source-specific characteristics of GHG emissions and sinks.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.3
• /
• pp.371-381
• /
• 2016

This paper presents a study on reliability assessment and new contribution function development of power system including Wind Turbine Generator(WTG) combined with Battery Energy Storage System(BESS). This paper develops and proposes new reliability contribution function of BESS installed at wind farms. The methodology of reliability assessment, using Monte Carlo Simulation(MCS) method to simulate sample state duration, is proposed in detail. Forced Outage Rate(FOR) considered probabilistic approach for conventional generators is modelled in this paper. The penetration of large wind power can make risk to power system adequacy, quality and stability. Although the fluctuation of wind power, BESS installed at wind farms may smooth the wind power fluctuation. Using small size system as similar as Jeju island power system, a case study of reliability evaluation and new proposed contribution function of power system containing WTG combined with BESS is demonstrated in this paper, which would contributes to BESS reliability contribution and assessment tools of actual power system in future.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.05a
• /
• pp.581-585
• /
• 2004

The purpose of this study is to suggest a method to support decision making of researchers, when we estimate the safety of the high-speed railway using F-AHP. To apply this method, Korean type of high-speed railway was engaged, and the 8 Stages of accident type and the five criteria were suggested that we must meet. Then, the interview with the researchers working for high-speed railway was used to confirm the alternatives suggested. The employed F-AHP for this study estimate using emotional words based on AHP of Saaty, so it is very good to estimate the high-speed railway safety.