• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.293-296
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• 1997

Robust stability conditions for discrete-time variable structure control is proposed. Conventionally the discrete-time variable structure control method with a variable structure uncertainty compensator approach requires a bounded changing rate of the uncertainties to ensure robust stability. However, when uncertainties vary as a function of state variables, which occur with parametric uncertainties, it is not reasonable to assume a bounded variation on the uncertainties. In this paper, uncertainties are assumed to consist of exogenous disturbances and parametric uncertainties. An uncertainty compensator is used to deal with the former, and a robust stability condition is derived using Small Gain Theorem for the latter.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.492-497
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• 2006

This study gives the results of the measurements and analysises of the reverberation times in a small room such as apartment houses. We measured the RT by changing measurement conditions, which were sound sources. sound source's positions, receiving point & height, sampling time and so on. The critical factor affecting reverberation time was sound source in unoccupied houses and the reverberation time differences between result of RT using impulsive and interrupted sound source was 0.3sec at 500Hz frequency. And the difference of RT due to sound sources affected the sound insulation such as apparent sound reduction index and sound level difference about 1dB at each frequency in unoccupied houses.

• IE interfaces
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• v.20 no.3
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• pp.407-417
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• 2007

Owing to a real-time innovative infrastructure driven by destructive technology revolution, the business environment has been changed dramatically. In order to respond fast to a continuously and unpredictably changing business environment, the business entities, such as business process participants, customers, distributers, and partners, should have an agile paradigm which is able to acquire and share the real time information adaptively. As a 21st century business paradigm having such adaptability and responsiveness has been introduced and called the "Real-Time Enterprise (RTE)" strategy. In this paper, we investigate the various innovation cases adopting the RTE strategy. After briefly addressing the concept and the value of RTE strategy, we discuss the models and the frameworks used in outstanding international and domestic enterprises. We believe that this case study can provide a good guide to many enterprises planning to adopt a RTE strategy for building competitive advantage in today's world of global competition.

• Earthquakes and Structures
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• v.6 no.2
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• pp.217-235
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• 2014

In this paper, different feedback control strategies are presented for active seismic control using proportional-integral-derivative (PID) type controllers. The parameters of PID controller are found by using an numerical algorithm considering time delay, maximum allowed control force and time domain analyses of shear buildings under different earthquake excitations. The numerical algorithm scans combinations of different controller parameters such as proportional gain ($K_p$), integral time ($T_i$) and derivative time ($T_d$) in order to minimize a defined response of the structure. The controllers for displacement, velocity and acceleration feedback control strategies are tuned for structures with active control at the first story and all stories. The performance and robustness of different feedback controls on time and frequency responses of structures are evaluated. All feedback controls are generally robust for the changing properties of the structure, but acceleration feedback control is the best one for efficiency and stability of control system.

• Journal of Information Display
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• v.10 no.4
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• pp.188-194
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• 2009

Conventional stereoscopic (3D) displays using binocular parallax generate unnatural conflicts between convergence and accommodation. These conflicts can affect the observer's ability to fuse binocular images and may cause visual fatigue. In this study, time series changes in visual fatigue and depth sensation when viewing stereoscopic images with changing parallax were examined. In particular, the physiological changes, including the subjective symptoms of visual fatigue, when viewing five parallax conditions, were examined. Then a comparative analysis of the 2D and 3D conditions was performed based on the visual function. To obtain data regarding the visual function, the time series changes in the spontaneous-blinking rate before and during the viewing of 3D images were measured. The time series change results suggest that 2D and 3D images cause significantly different types of visual fatigue over the range of binocular disparity.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.493-496
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• 1998

Several sensorless vector control methods of induction motor have been proposed, but these methods don't have the satisfying performance to the change of the rotor time constant. Therefore, this paper proposes the sensorless vector control method which estimates the rotor speed using MRAS and compensates the rotor time constant using current error feedback at the same time. This method can guarantees the accurate performance of sensorless vector control while the rotor speed and the rotor time constant are changing. This method is verified by computer simulation using SIMULINK in MATLAB.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.5
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• pp.658-663
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• 1999

2D sliced CT images hardly express the human disease in a space. This space expression can be reconstructed into 3D image by piling up the CT sliced image in succession. In medical image, in order to get the reconstructed 3D images, expensive system or much calculation time is needed. But by changing the method of reconstruction procedure and limit the range, the reconstruction time could be reduced. In this study, to reduce the processing time and memory, we suggested a method of interpolation and ray casting processing at the same time in a limited range. Such a limited range processing have advantages that we could reduce the unnecessary interpolation and ray casting. Through a experiment, it is founded that the reconstruction time and the memory was much reduced.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.10a
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• pp.143-146
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• 2005

Human activity pattern has been changed as the contemporary urban society changes. Diverse activities repeat regular patterns as time passes. Diagram is a simple drawing which aims to organize and unify various information. The elements of the social behaviour could be spatialized by means of diagram applications. By using diagrams, architects understand contemporary urban society and form new space conditions. Time-based activity patterns consists of activity pattern in a restricted space and in urban structure for space use. Activity patterns for different time zones are explained by two types of diagrams, space occupation and flexibility of space, By the characteristic of space system structred by these diagrams, activities and programs are rearranged and variety of space is allowed through flexibility. Also, programs are mixed to apply to simultaneous occurrence of ever-changing human activities.

• The Korean Nurse
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• v.30 no.1
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• pp.51-62
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• 1991

The Study was carried out for the purpose of investigating the degree of perception in nursing activities. This study reports perceptions of nurses on the choices they make among competing activities, contrasts this perception with their opinion of what tasks they would like to spend time on. A sample of 231 clinical nurses was selected to participate in this study at two genernal hospitals in Seoul. The data was collected from July 10th to 25th, 1990. Subjects were instructed to rate one of five points likert type scale on the 43 items of nursing activities. Analysis of data was done by means of the SPSS-X Program using frequency, t-test and ANOVA. The results of this study were as follows; 1. The characteristics of the subjects were as follows: The age group of 25-29 yeares was 45.9%. For religion, Christians had the highest score, 68.4 % and singles in subjects were 81.4%. For academic background, 64.5% were graduated from nursing junior colleges. In the subjects, staff nurses were 86.6%. 22.5% of them had worked for less than 1 year and 20.8% had 37 months to 5 years experience at the time of the survey. 62.8% were satisfied with the job. 2. The perception level of nursing activities: 1) The mean score for perception of professional nursing functions was 4.157 point, with a maximum score set. at 5 points. The mean score for perception of priorities was 3.781. Perception of spending time was 3.932. 2) In perception of professional nursing functions, more important items were Aseptic technique (4.866), Shift and exchange of information concerning patients(4.654), Observing patients (4.799). Less important items were Transporting patients(3.411), Changing linens(3.442), Giving a bed shampoo (3.506). In priorities, more important ones. were Aseptic technique(4, 706), Shift and exchange of information concerning patients (4.524.), Observing patients(4.390), Taking vital signs (4.355). And less important ones were Changing linens (3.100), Giving bed baths(3.113), Giving back rubs(3.121). In spending time, more important ones were Aseptic technique(1.706), Observing patients (4.532), Shift and exchange of information concerning patients(4.532). And less important ones were Changing lines(3.368), Transporting patients(3.394), Giving bed baths(3.450). 3) In the role perception level, the mean distribution of perception was 3.511- 4.335; the role was perceived to be in order of frequency as a facilitator, coordinator, change agent and advocator role. The most important scale of factors by nursing activities was indirect nursing activities.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.71-78
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• 2007

Input shaping is known to be a very effective tool for suppressing residual vibration without introducing any complicated sensors and feedback control. Real-time input shaping schemes necessitate a process such that the input command is discretized to deal with non-prescribed, real-time input. Thus parameters associated with input command discretization, such as time spacing and duration time, are unknowns which affect the performance of input shaping schemes, especially for small and fast XY stages. This paper investigates the effects of input command discretization parameters, such as time spacing and duration time, on the dynamic performance of XY stages subjected to real-time input shaping. An experimental system is developed which is equipped with an XY stage driven by servo-motors and real-time user command. Experiments are performed to investigate the dynamic performance of XY stage by changing these parameters and to yield a strategy to gain better performance.