• Journal of Welding and Joining
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• 제29권4호
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• pp.48-53
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• 2011

A thermal distortion analysis which takes strains directly as boundary conditions removed barrier of analysis time for the evaluation of welding distortion in a large shell structure like ship block. If the FE analysis time is dramatically reduced, the structure modeling time or the input-value calculating time will become a new issue. On the contrary to this, if the calculation time of analysis input-value is dramatically reduced and its results also are more meaningful, a little longer analysis time could be affirmative. In this study, instead of using inherent strain based on elastic analysis, a thermal strain based on elasto-plastic analysis is used as the boundary condition of weldments in order to evaluate the welding distortion. Here, the thermal strain at the weldment was established by using a stress-strain curve established from the test results. It is possible to automatically recognize the modeling induced-stiffness in the shrinkage direction of welded or heated region. The validity of elasto-plastic thermal distortion analysis was verified through the experiment results with various welding sequence.

• 가족자원경영과 정책
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• 제19권1호
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• pp.163-180
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• 2015

The purpose of this study was to explore a typology of time allocation, investigate determinants of time allocation types, and analyze differences in time use satisfaction by the types of time use of the elderly. The data source for this research was the 2009 Time Use Survey conducted by the Korea National Statistical office (KNSO). The 4,699 time diaries (3,552 for weekday, 1,147 for Sunday) completed by the elderly over the age of 60 were analyzed using mean, standard deviation, chi-square, cluster analysis, ANOVA analysis, Duncan test, and multinomial logistic regression analysis. Time allocation of the elderly was classified into four types: personal care oriented, work oriented, leisure oriented, and balanced type. Gender, age, education, employment status, income, and the presence of spouse were identified as determinants for each type. According to the types of time allocation, time use satisfaction was different on week days.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.254-257
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• 2003

Statistical analysis is performed to estimate the correlations between geological or geographical factor and groundwater inflow rates in the Seoul subway system. Correlation analysis shows that among several geological and geographical factors fractures and streams have most strong effects on inflow rate into tunnels. In particular, subway line 5∼8 are affected more by these factors than subway line 1∼4. Time series analysis is carried out to forecast groundwater inflow rate. Time series analysis is a useful empirical method for simulation and forecasts in case that physical model can not be applied to. The time series of groundwater inflow rates is calculated using the observation data. Transfer function-noise model is applied with the precipitation data as input variables. For time series analysis, statistical methods are performed to identify proper model and autoregressive-moving average models are applied to evaluation of inflow rate. Each model is identified to satisfy the lowest value of information criteria. Results show that the values by result equations are well fitted with the actual inflow rate values. The selected models could give a good explanation of inflow rates variation into subway tunnels.

• 한국압력기기공학회 논문집
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• 제17권2호
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• pp.137-144
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• 2021

The mode superposition time history analysis method is commonly used in a seismic analysis. The maximum response in the time history analysis can be derived by combining the responses of individual modes. The residual mode response is the response of the modes which are not considered in the time history analysis. In this paper, the residual vector method to consider the residual mode response in the time history analysis is introduced and evaluated. Seismic analyses for a sample structure model and a reactor vessel model are performed to evaluate the residual vector method. The analysis results show that residual mode response is well calculated when the residual vector method is used. It is confirmed that the residual vector method is useful and acceptable to consider the residual mode response in a seismic analysis of the nuclear power plant equipment.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.194-203
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• 2005

The process of guaranteeing that a distributed real-time control system will meet its timing constraints, is referred to as schedulability analysis. However, schedulability analysis algorithm cannot be simply used to analyze the system because of complex calculations of algorithm. It is difficult for control engineer to understand the algorithm because it was developed in a software engineer's position. In this paper we introduce a Response-time Analysis Tool(RAT) which provides easy way far system designer to analyze the system by encapsulating calculation complexity. Based on the RAT, control engineer can verify whether all real-time tasks and messages in a system will be completed by their deadline in the system design phase.

• Structural Engineering and Mechanics
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• 제41권5호
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• pp.675-689
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• 2012

Most connections of steel structures exhibit flexible behaviour under cyclic loading. The flexible connections can be assumed as nonlinear rotational springs attached to the ends of each beam. The nonlinear behaviour of the connections can be considered by suitable moment-rotation relationship. Time-history analysis by direct integration method can be used as a powerful technique to determine the nonlinear dynamic response of the structure. In conventional numerical integration, the response is evaluated for a series of short time increments. The limitations on the size of time intervals can be removed by using Chen and Robinson improved time history analysis method, in which the integrated displacements are used as the new variables in integrated equation of motion. The proposed method permits longer time intervals and reduces the computational works. In this paper the nonlinearity behaviour of the structure is summarized on the connections, and the step by step improved time-history analysis is used to calculate the dynamic response of the structure. Several numerical calculations which indicate the applicability and advantages of the proposed methodology are presented. These calculations illustrate the importance of the effect of the nonlinear behaviour of the flexible connections in the calculation of the dynamic response of steel frames.

• 대한건축학회연합논문집
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• 제21권3호
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• pp.11-21
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• 2019

The purpose of this study was to present an analysis model for finding the correlation between visibility and evacuation time as users move in the outpatient department of the general hospital. The spatial scope of the study was limited to the first floor and second floor which are used for the outpatient department. Traffic density in outpatient departments was surveyed on site. Based on the surveyed traffic density, the evacuation simulation model was established for calculating the escape route and evacuation time for an individual user. The traffic density of the outpatient department as per the evacuation time was also calculated. With using evacuation simulations, the flow of evacuees was calculated through the density of traffic over the time of evacuation. Visibility data were set in the simulation model for users' escape routes. A correlation analysis between the product of evacuation flow measure and visibility measure of the evacuation population and evacuation time was performed. The analysis result showed negative correlation within a specific distance range. This study presented an analysis model showing that the evacuation condition considering spatial visibility in the outpatient department of general hospital visibility was negatively related to the analyzed evacuation time at the design stage.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2012년 춘계학술대회
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• pp.117-137
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• 2012

In the ALC(Autoclaved lightweight concrete) manufacturing process, if the pre-cured semi-cake is removed after proper time is passed, it will be hard to retain the moisture and be easily cracked. Therefore, in this research, we took the research by multiple regression analysis to find relationship between variables for the prediction the hardness that is the control standard of the removal time. We study the relationship between Independent variables such as the V/T(Vibration Time), V/T movement, expansion height, curing time, placing temperature, Rising and C/S ratio and the Dependent variables, the hardness by multiple regression analysis. In this study, first, we calculated regression equation by the regression analysis, then we tried phased regression analysis, best subset regression analysis and residual analysis. At last, we could verify curing time, placing temperature, Rising and C/S ratio influence to the hardness by the estimated regression equation.

• 한국군사과학기술학회지
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• 제19권3호
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• pp.371-378
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• 2016

The most important things in real-time systems are that a system guarantees to meet its deadline and to operate in its predictable range. When we design a real-time system, we need to verify whether the system can meet its deadline through schedulability analysis. There are several kinds of schedulability analysis technique for fixed priority scheduling systems. But as we all know, we can't perform schedulability analysis in design time because we can't estimate upper bounds on execution time of each task. So we used a similar real-time system to estimate upper bounds on execution time for our system, and then we performed schedulability analysis and verified that our system designed can meet its deadline.

• Journal of Information Processing Systems
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• 제10권2호
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• pp.300-313
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• 2014

Various Time Synchronization protocols for a Wireless Sensor Network (WSN) have been developed since time synchronization is important in many time-critical WSN applications. Aside from synchronization accuracy, energy constraint should also be considered seriously for time synchronization protocols in WSNs, which typically have limited power environments. This paper performs analysis of prominent WSN time synchronization protocols in terms of power consumption and test by simulation. In the analysis and simulation tests, each protocol shows different performance in terms of power consumption. This result is helpful in choosing or developing an appropriate time synchronization protocol that meets the requirements of synchronization accuracy and power consumption (or network lifetime) for a specific WSN application.