• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1990.10a
• /
• pp.22-27
• /
• 1990

Since an eigenvalue problem in structural analysis has been recognized as an important process for the assessment of structural strength, it is usually to be carried out the eigenvalue analysis or buckling analysis of structures when the compression behabiour of the member is dorminant. In general, various variables involved in the eigenvalue problem have also shown their variability. So it is natural to apply the probabilistic analysis into such problem. Since the limit state equation for the eigenvalue analysis or buckling reliability analysis is expressed implicitly in terms of random variables involved, the probabilistic finite element method is combined with the conventional reliability method such as MVFOSM and AFOSM for the determination of probability of failure due to buckling. The accuracy of the results obtained by this method is compared with results from the Monte Carlo simulations. Importance sampling method is specially chosen for overcomming the difficulty in a large simulation number needed for appropriate accurate result. From the results of the case study, it is found that the method developed here has shown good performance for the calculation of probability of buckling failure and could be used for checking the safety of the calculation of probability of buckling failure and could be used for checking the safely of frame structure which might be collapsed by either yielding or buckling.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.9 no.6
• /
• pp.133-141
• /
• 2009

The main objective of water distribution system is to supply enough water to users with proper pressure. Hydraulic analysis of water distribution system can be divided into Demand Driven Analysis (DDA) and Pressure Driven Analysis (PDA). Demand-driven analysis can give unrealistic results such as negative pressures in nodes due to the assumption that nodal demands are always satisfied. Pressure-driven analysis which is often used as an alternative requires a Head-Outflow Relationship (HOR) to estimate the amount of possible water supply at a certain level of pressure. However, the lack of data causes difficulty to develop the relationship. In this study, effective supply, which is the possible amount of supply while meeting the pressure requirement in nodes, is proposed to estimate the serviceability and user's convenience of the network. The effective supply is used to calculate Subsystem Importance Index (SII) which indicates the effect of isolating a subsystem on the entire network. Harmony Search, a stochastic search algorithm, is linked with EPANET to maximize the effective supply. The proposed approach is applied in example networks to evaluate the capability of the network when a subsystem is isolated, which can also be utilized to prioritize the rehabilitation order or evaluate reliability of the network.

• Computational Structural Engineering
• /
• v.7 no.1
• /
• pp.109-116
• /
• 1994

In this paper, various reliability analysis methods for calculating a probability of failure are investigated for their accuracy and efficiency. Crude Monte Carlo method is used as a basis for the comparison of various numerical results. For the sampling methods, Importance Sampling method and Directional Simulation method are considered for overcoming a drawback of Crude Monte Carlo method. For the approximate methods, conventional Rackwitz-Fiessler method. 3-parameter Chen-Lind method, and Rosenblatt transformation method are compared on the basis of First order reliability method. As a Second-order reliability method, Curvature-Fitting paraboloid method, Point-fitting paraboloid method, and Log-likelihood function method are explored in order to verify the accuracy of the reliability calculation results. These methods mentioned above would have some difficulty unless the limit state equation is expressed explicitly in terms of random design variables. Thus, there is a need to develop some general reliability methods for the case where an implicit limit state equation is given. For this purpose, Response surface method is used where the limit state equation is approximated by regression analysis of the response surface outcomes resulted from the structural analysis. From the application of these various reliability methods to three examples, it is found that Directional Simulation method and Response Surface method are very efficient and recommendable for the general reliability analysis problem cases.

• The Journal of the Korean Society for Microbiology
• /
• v.35 no.2
• /
• pp.129-139
• /
• 2000

Acinetobacter baumannii strains are emerging pathogens of the nosocomial infection with an increasing frequency in recent years. The therapeutic difficulty due to the wide spread of multiple resistant strains was major problem in A. baumannii infection. It seems likely that high frequency of A. baumannii infection will be increasing epidemiological importance in the future. However, the current limited understanding of the epidemiology of A. baumannii infections is caused by lack of a rapid and practical method for the molecular characterization of A. baumannii strains. This study was undertaken to determine molecular types and genetic similarity among A. baumannii strains isolated from four hospitals by RAPD analysis. Eighty-five strains, including 40 from Chunnam University Hospital, 27 from Dankook University Hospital, 15 from Yonsei University Hospital, and 3 from Seonam University Hospital, were classified into three molecular types. Molecular type II was the most common pattern and included 72 strains. All strains from Dankook University Hospital and 40 strains from Chunnam University Hospital belonged to molecular type I or II. A. baumannii strains form Yonsei University Hospital were very distant similarity values. The range of genetic similarity values among 85 strains of A. baumannii was 0.26 to 1.00. Although phenotypes including biotype and antimicrobial resistance pattern of A. baumannii strains were same or very similar to each other, their RAPD patterns were quite different. Typing with phenotypes was found to be less reliable than molecular typing by RAPD analysis. These results suggest that RAPD analysis provides rapid and simple typing method of A. baumannii strains for epidemiological studies. This work is the first epidemiological report of A. baumannii infections in Korea and it is hoped that results of this work may contribute to a better understanding of the clinical importance and epidemiology of A. baumannii strains.

• Journal of Convergence for Information Technology
• /
• v.9 no.9
• /
• pp.117-125
• /
• 2019

This study aims to evaluate of validity and reliability of the job performance tool already developed for the elementary school health teachers. 305 health teachers responded to the questionnaire composed of 50 items. The validity and reliability of the tool were verified by confirmatory factor analysis. That were composed of 8 sub-categories and had 4 factors. The importance, frequency, and difficulty of the four factors were classified according to the questionnaire criteria, but the importance of health promotion is classified as one new item factor. The statistical significance of the fit of the model was 3.664 (df = 246, p<0.001), RMSEA=0.09, NFI=0.85 and CFI=0.88. The internal consistency of the subscales was Cronbach's ${\alpha}$ of 0.88 to 0.96. The internal consistency of the subscales, Cronbach's ${\alpha}$ was 0.88~0.96. This study shows that the analysis tool for primary school health teacher is valid and reliable as a measurement tool.

• Korean Journal of Community Nutrition
• /
• v.25 no.2
• /
• pp.112-125
• /
• 2020

Objectives: Diet and incidence of chronic diseases are highly related. This study examined the characteristics of dietary safety awareness and competency for chronic disease prevention among adults. Methods: Data were collected from 247 adults in Daegu and Gyeongbuk areas using a self-administered questionnaire in May and June of 2018. Data were analyzed by frequency analysis, χ²-test, factor analysis, reliability analysis, t-test, one-way analysis of variances, and correlation. Results: The results of the factor analysis indicate that dietary safety awareness of health management was classified into chronic disease anxiety and obsession. Awareness of dietary safety management was sub-grouped into difficulty in acquiring knowledge, lack of awareness of over and malnutrition, food safety anxiety, importance of weight management, education requirement for cancer prevention, and knowledge. Dietary safety behavior composed of a balanced diet, unhealthy diet, and health-functional pursuit. Dietary safety management competency was comprised of health management, food management, and cooking. The competency scores of dietary safety management factors were significantly different according to sex, age, and education level (P < 0.05). Balanced diet factor was significantly correlated with knowledge, health-functional pursuit, health management, food management, and cooking capacity factors (P < 0.01). Conclusions: Active education for dietary safety management competency according to age, gender, and education level should provide dietary safety education to reduce anxiety and obsession regarding chronic diseases and sustainable health management.

• Korean Management Science Review
• /
• v.9 no.1
• /
• pp.31-40
• /
• 1992

The size of software collection at any organization is increasing rapidly with the use of computer becomes popular for various applications. This trend points out the importance of proper 'catalog'or 'directory' for software collections, however, only 'title list' is found in practice. The problem of no proper directory with software collection would be more serious than the problem with book collection since browsing is not possible with softwares. Many of the expensive softwares will be a waste of money to purchase and to hold if no catalog about them is provided. In this paper the difficulties in applying AACR2 to software cataloging and the most important characteristic of computer software are discussed as well as presenting the necessity of localized information due to the requirement of a machine to be used, the difficulty using subject-based-call-number scheme, an expected way of searching software to design a location indicator, software qualifications to be cataloged, and so on. In addition, an analysis of randomly selected softwares after a cataloging practice is followed.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2005.10a
• /
• pp.3-9
• /
• 2005

The recent notion of Network Centric Warfare (NCW) emphasizes the ability to distribute right information at the right time to maximize the combat effectiveness. Accordingly, in the modern combat system the importance of non-physical element, such as communication system is increasing. However, an NCW-support communication network system is expensive. Therefore, it is essential to develop a proper combat system evaluation method to establish an efficient NCW-support combat system. Traditionally, combat system effectiveness is measured in terms of physical elements such as men and fire power. Obviously, such method is hardly applicable to a modern combat system To overcome this difficulty, we propose an evaluation model based on CA (Cellular Automata) simulation. A set of preliminary combat simulations show that CA simulation may be promising in evaluating non-physical element of a modem combat system.

• Journal of the Korean institute of surface engineering
• /
• v.28 no.1
• /
• pp.23-33
• /
• 1995

AISI 304 stainless steel has high resistance to corrosion due to the presence of a self-healing chromium oxide film on the surface, which also accounts for the difficulty in plating. Surface cleaning of this alloy is of fundamental importance in gold plating since its effectiveness puts an upper limit on the quality of the final coating. The cleaning of AISI 304 stainless steel was investigated with elimination of artificial passive oxide film and degreasing of remaining buffing wax as stearic acid. The familiar cleaning methods i.e. ultrasonic cleaning, electro-cleaning and activation treatment were fabricated in this study. Activation treatment showed best cleaning efficiency for elimination of passive oxide film among these methods, which was also confirmed by AES (Auger electron spectrometer) analysis. However, the best condition of cleaning was obtained by combining these methods. Electrocleaning time, for degreasing the stearic acid layer, was decreased with increasing amount of added KCN.

• Korean Management Science Review
• /
• v.22 no.2
• /
• pp.135-145
• /
• 2005

The recent notion of Network Centric Warfare (NCW) emphasizes the ability to distribute the right information at the right time to maximize the combat effectiveness. Accordingly, in the modern combat system, the importance of non-physical elements, such as a communication system, is increasing. However, an NCW-support communication network system is expensive. Therefore, it is essential to develop a proper combat system evaluation method to establish an efficient NCW-support combat system. Traditionally, combat system effectiveness is measured in terms of physical elements such as men and fire power, Obviously, such method is hardly applicable to a modern combat system. To overcome this difficulty, we propose an evaluation model based on CA (Cellular Automata) simulation. A set of preliminary combat simulations show that CA simulation may be promising in evaluating non-physical element of a modern combat system.