• Structural Engineering and Mechanics
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• v.4 no.5
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• pp.497-511
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• 1996

The equivalent static force procedure and the response spectrum analysis method are widely used for seismic analyses of multi-story buildings. The equivalent static force procedure is one of the most simple but less accurate method in predicting possible seismic response of a structure. The response spectrum analysis method provides more accurate results while it takes much longer computational time. In the response spectrum method, dynamic response of a multi-story building is obtained by combining modal responses through a proper procedure such as SRSS or CQC method. Since all of the analysis results are expressed in absolute values, structural engineers have difficulties to combine them with the results obtained from the static analysis. Design automation is interrupted at this stage because of the difficulty in the decision of the most critical design load. Pseudo-dynamic analysis method proposed in this study provides more accurate seismic analysis results than those of the equivalent static force procedure since the dynamic characteristics of a structure is considered. And the proposed method has an advantage in combination of the analysis results due to gravity loads and seismic loads since the direction of the forces can be considered.

• Journal of the Korean Society of Safety
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• v.34 no.3
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• pp.75-82
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• 2019

The purpose of this study was to evaluate the effectiveness of a vibration feedback system in improving two safe seating postures of office workers. In addition, the relative effectiveness of positive and negative feedback procedures was examined. Participants were four office workers. The dependent variables were the percentages of time participants spent in the safe sitting postures including shoulder, back, and overall body positions during the experimental sessions. A multiple-baseline design counterbalanced across participants was adopted. For two participants, the negative procedure was introduced first after baseline and positive procedure was introduced in the next phase. For the other two participants, the sequence of introducing the positive and negative feedback procedures was reversed. The result showed that the vibration feedback system, regardless of the type of the procedure, was effective in improving the safe sitting postures for all participants. However, the difference between the two procedures was not clearly shown. The benefits of the automated observation and vibration feedback system in workers' safety were discussed.

• Korea Journal of Hospital Management
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• v.15 no.3
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• pp.47-68
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• 2010

One of the important complaint factors by the patients using medical institutions is various kinds of waiting time. This research is about the causal relationships among waiting time(application of waiting time, perceived of waiting time, fairness of waiting, explanation of the delay, acceptance possibility), service values, and customer satisfaction. The subjects for this study were 256 out-patients currently using seven general hospitals in the Busan area. The findings of the empirical analysis are as follows: First, the good application of waiting time or fair waiting time procedure didn't actually affect perceived waiting time. Second, though the application of waiting time didn't affect acceptance possibility, the fair procedure of waiting time had an affirmative effect on acceptance possibility. Third, even when there was enough explanation about the need to wait, it could shorten perceived waiting time but failed to get sufficient sympathy or agreement from the patients. Fourth, the possibility of acceptance following the sufficient sympathy of patients had an effect on shortening perceived waiting time. Fifth, perceived waiting time lowered customer satisfaction, but had no negative effect on service values. Finally, the ranges of acceptance possibility by the patients were found to increase customer satisfaction and maximize service values. In conclusion, every medical institution needs to focus on, first of all, shortening waiting time for more customer satisfaction and improved service values.

• Journal of the Korean Geotechnical Society
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• v.31 no.9
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• pp.53-68
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• 2015

Longitudinal strain is an important component of seismic design for buried pipelines. A design procedure which determines the wavelength from site natural period and shear wave velocity of the soil layer and closed-form solutions of pipelines under a harmonic motion is typically used in design. However, the applicability of the procedure has not yet been thoroughly investigated. In this paper, displacement-time histories extracted from 1D site response analyses are used in 3D shell-spring model to accurately predict the response of pipelines. The results are closely compared to those from the design procedure. The area of interest is East Siberia. Performing a site response analysis to determine site specific displacement time history is highlighted. The site natural period may be used to predict the predominant period of the acceleration time history, but cannot be used to estimate the predominant period of the displacement time history. If an accurate estimate of the predominant period of the displacement time history is provided, it is demonstrated that the design equation can be successfully used to predict the response of pipelines.

• Korean Journal of Digital Imaging in Medicine
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• v.14 no.2
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• pp.33-38
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• 2012

In EVAR procedure using long time C-arm, we studied exposure dose reduction and effeciency through measuring surgical staff's ESD by installing lead curtain operating table next to. The height 3 the spot (50cm, 100cm, 150cm) dose was measured on 2 locations for 600sec in the X-ray radiation considering the surgical staff's movement. To install the curtains, we compared before and after the dose. As a result, it can confirm that dose of the installation former of 50cm height and after is reduced about 75% and 91% in 2 locations. In 100cm height, the reduction of the dose was a bit confirmed. There as to dose value, measured on 150cm height the installation former and after was nearly no change. This research examined the exposure dose about the radiation of the surgical staff during EVAR procedure in which the operation time is the long time. It was implemented in the object that it reduces the radiation exposure. It could confirm the certain effect of the experimental result exposure dose reduction In EVAR procedure using long time C-arm, we studied exposure dose reduction and effeciency through measuring surgical staff's ESD by installing lead curtain operating table next to. The height 3 the spot (50cm, 100cm, 150cm) dose was measured on 2 locations for 600sec in the X-ray radiation considering the surgical staff's movement. To install the curtains, we compared before and after the dose. As a result, it can confirm that dose of the installation former of 50cm height and after is reduced about 75% and 91% in 2 locations. In 100cm height, the reduction of the dose was a bit confirmed. There as to dose value, measured on 150cm height the installation former and after was nearly no change. This research examined the exposure dose about the radiation of the surgical staff during EVAR procedure in which the operation time is the long time. It was implemented in the object that it reduces the radiation exposure. It could confirm the certain effect of the experimental result exposure dose reduction.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1169-1172
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• 1996

A time-optimal control law for quick, strongly nonlinear systems has been developed and demonstrated. This procedure involves the utilization of neural networks as state feedback controllers that learn the time-optimal control actions by means of an iterative minimization of both the final time and the final state error for the known and unknown systems with constrained inputs and/or states. The nature of neural networks as a parallel processor would circumvent the problem of "curse of dimensionality". The control law has been demonstrated for a velocity input type motor identified by a genetic algorithm called GENOCOP.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.219-224
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• 1988

A decentralised computational procedure is proposed for the optimal feedback gain matrix of large-scale discrete-time systems with time-delays. The constant feedback gain matrix is computed from the optimal state and input trajectries obtained hierarchically by the interaction prediction method. All the calculation in this approach are done off-line. The resulting gains are optimal for all the initial conditions. The interaction prediction method is applied to time-delay large-scale systems with general structures by extending the dimensions of coupling matices. A numerical exampie illustrates the algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.237-237
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• 2000

In this paper, The modified dead-time compensator for plants with an integrator and long dead time is proposed. The design procedure takes account of the closed-loop performance and robustness. The tuning of the controller can be done using some information about the plant and its uncertainties. The proposed controller is compared to others recently presented in the literature. Some simulation results verify good closed-performance and robustness of the proposed DTC.

• Structural Engineering and Mechanics
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• v.26 no.5
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• pp.499-516
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• 2007

An experimental method denoted as Impulse Method is proposed as a cost-effective non-destructive technique for the on-site evaluation of concrete elastic modulus in existing structures: on the basis of Hertz's quasi-static theory of elastic impact and with the aid of a simple portable testing equipment, it makes it possible to collect series of local measurements of the elastic modulus in an easy way and in a very short time. A Hypothesis Testing procedure is developed in order to provide a statistical tool for processing the data collected by means of the Impulse Method and assessing the possible occurrence of significant variations in the elastic modulus without exceeding some prescribed error probabilities. It is based on a particular formulation of the renowned sequential probability ratio test and reveals to be optimal with respect to the error probabilities and the required number of observations, thus further improving the time-effectiveness of the Impulse Method. The results of an experimental investigation on different types of plain concrete prove the validity of the Impulse Method in estimating the unknown value of the elastic modulus and attest the effectiveness of the proposed Hypothesis Testing procedure in identifying significant variations in the elastic modulus.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.10 s.253
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• pp.1209-1218
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• 2006

Precision servomechanisms are widely used in machine tool, semiconductor and flat panel display industries. It is important to improve contouring accuracy in high-precision servomechanisms. In order to improve the contouring accuracy, cross-coupled control systems have been proposed. However, it is very difficult to select the controller parameters because cross-coupled control systems are multivariable, nonlinear and time-varying systems. In this paper, in order to improve contouring accuracy of a biaxial servomechanism, a cross-coupled controller is adopted and an optimal tuning procedure based on an integrated design concept is proposed. Strict mathematical modeling and identification process of a servomechanism are performed. An optimal tuning problem is formulated as a nonlinear constrained optimization problem including the relevant controller parameters of the servomechanism. The objective of the optimal tuning procedure is to minimize both the contour error and the settling time while satisfying constraints such as the relative stability and maximum overshoot conditions, etc. The effectiveness of the proposed optimal tuning procedure is verified through experiments.