• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.10a
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• pp.377-386
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• 2000

Hybrid mass dampers consist of passive tuned mass dampers and active mass dampers. They have the advantage that passive tuned mass dampers are still operated even when active mass dampers are stopped by excessive disturbances or power failure. This paper begins first with the comparative analysis of tuned mass dampers, hybrid mass dampers, and active mass dampers. Next more detailed study is carried out on the hybrid mass dampers: cascade hybrid mass dampers (CHMD) and active tuned mass dampers (ATMD). CHMD is regarded as more reasonable device because of its lighter active mass than ATMD's. However CHMD can not neglect stroke saturation problem caused by the length limitation of active damper mass. We compensate the saturation problem with nonlinear restoring force. The restoring force is calculated based on the states and phases of active mass dampers and added to the control force. It is shown that the presented compensation method prevents CHMD from saturation behavior without apparent changes of control force and responses compared to those in case of not considering the saturation problem.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.737-739
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• 1996

Abnormal conditions and disturbances in distribution system cause an immediate influence to the customers. Conventional detection schemes for the distribution abnormalities have been applied in limited extents mainly because of their low reliability. In this paper, we developed a disturbance identification system which monitors the load level after a transient, checks the harmonic behavior of the load, and finally makes decision on the cause of the disturbance. This system identifies and discriminates overcurrent faults, arcing ground faults, recloser activities, and foreign object or tree contacts. In the implementation of the identification system, we applied fuzzy logic to better represent some variables whose Quantities are expressed only in non-numerical terms.

• Journal of Power Electronics
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• v.7 no.2
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• pp.140-145
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• 2007

The negative output elementary Luo converter is a newly developed DC-DC converter. Due to the time-varying and switching nature of the above converter, its dynamic behavior becomes highly non-linear. Conventional controllers are incapable of providing good dynamic performance for such a converter and, hence, a neural network is utilized as a controller in this work. The performance of the chosen Luo converter using PI versus neuro controls is compared under load and line disturbances using MATLAB and TMS320F2407 DSP. The results validate the superiority of the developed neuro controller.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1656-1663
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• 2004

As the structures become larger, higher and more complicated, the demand for safety level has increased. In recent years, TLD(Tuned Liquid Damper) proved to be a successful control tool for reducing structural vibrations. For this reason, the influence of some key parameters of the U-type TLD on the dynamic response is studied. And simple and effectively developed learning control logic is used to control vibration of U type Tuned Liquid Damper system. The purpose of this paper is design optimal control system to deal with unknown errors from non linearity and variation that cost modeling difficulty in complex structure and is followed with the desired behavior. Finally this hybrid control method applied to U type Tuned Liquid Damper structure gives the benefit from better performance of precision and stability of the structure by reducing vibration effect. This research leads to safety design in various structure to robust unspecified foreign disturbances such as windy-load and earthquake.

• The Journal of Korea Robotics Society
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• v.14 no.4
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• pp.348-356
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• 2019

The backdrivable servovalve is a desirable component for force and interaction control of hydraulic actuation systems because it provides direct force generation mechanical impedance reduction by its own inherent backdrivability. However, high parametric uncertainty and friction effects inside the hydraulic actuation system significantly degrade its advantage. To solve this problem, this letter presents a disturbance-adaptive robust internal-loop compensator (DA-RIC) to generate ideal interactive control performance from the backdrivable-servovalve-based system. The proposed control combines a robust internal-loop compensator structure (RIC) with an explicit disturbance estimator designed for asymptotic disturbance tracking, such that the controlled system provide stable and ideal dynamic behavior for impedance control, while completely compensating the disturbance effects. With the aid of a backdrivable servovalve, we show that the proposed control structure can be implemented based on a simplified nominal model, and the controller enables implementation without accurate knowledge of the target system parameters and disturbances. The performance and properties of the proposed controller are verified by simulation and experiments.

• Coupled systems mechanics
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• v.13 no.1
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• pp.21-41
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• 2024

This paper is concerned with the disturbances in a transversely isotropic new modified couple stress homogeneous thermoelastic rotating medium under the combined influence of Hall currents, magnetic fields, and mechanical sources represented by inclined loads. The application of Laplace and Fourier transform techniques are used for the derivation of analytical expressions for various physical quantities. As an application,the bounding surface is subjected to uniformly and linearly distributed force (mechanical force). Present model contains length scale parameters that can capture the size effects. Numerical inversion techniques has been used to provide insights into the system's behavior in the physical domain. The graphical representation of numerical simulated results has been presented to emphasize the impact of rotation and inclined line loads on the system, enhancing our understanding of the studied phenomena. Further research can extend this study to investigate additional complexities and real-world applications.

• Current Optics and Photonics
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• v.1 no.2
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• pp.107-112
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• 2017

An adaptive optics system can be simulated or analyzed to predict its closed-loop performance. However, this type of prediction based on various assumptions can occasionally produce outcomes which are far from actual experience. Thus, every adaptive optics system is desired to be tested in a closed loop on an optical test bench before its application to a telescope. In the close-loop test bench, we need an atmospheric simulator that simulates atmospheric disturbances, mostly in phase, in terms of spatial and temporal behavior. We report the development of an atmospheric turbulence simulator consisting of two point sources, a commercially available deformable mirror with a $12{\times}12$ actuator array, and two random phase plates. The simulator generates an atmospherically distorted single or binary star with varying stellar magnitudes and angular separations. We conduct a simulation of a binary star by optically combining two point sources mounted on independent precision stages. The light intensity of each source (an LED with a pin hole) is adjustable to the corresponding stellar magnitude, while its angular separation is precisely adjusted by moving the corresponding stage. First, the atmospheric phase disturbance at a single instance, i.e., a phase screen, is generated via a computer simulation based on the thin-layer Kolmogorov atmospheric model and its temporal evolution is predicted based on the frozen flow hypothesis. The deformable mirror is then continuously best-fitted to the time-sequenced phase screens based on the least square method. Similarly, we also implement another simulation by rotating two random phase plates which were manufactured to have atmospheric-disturbance-like residual aberrations. This later method is limited in its ability to simulate atmospheric disturbances, but it is easy and inexpensive to implement. With these two methods, individually or in unison, we can simulate typical atmospheric disturbances observed at the Bohyun Observatory in South Korea, which corresponds to an area from 7 to 15 cm with regard to the Fried parameter at a telescope pupil plane of 500 nm.

• Journal of Korean Academy of Nursing
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• v.10 no.1
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• pp.57-64
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• 1980

The purpose of the study was to find out the relationship between experienced stressful events and its coping behavior within mentally wellness and illness, and to define the effective coping method under the stressful situation. By doing so, during the period of April, 1978- to March, 1979 the objects of this study were 100 persons who were under the psychiatric facilities in their first hospitalization, and who were registered in psychiatric out patient department in the form general hospitals located at Seoul selected as a experimental group. As a control group 100 persons who never experienced psychiatric treatment who were not under the current medical treatment, and who were tarring appropriate social roles in their community were selected, and in both groups utilized questimaires for Social Readjustment Pating Scale and Coping Scale. This study was tested by X$^2$ examinationand by F-ratio（analysis of variance). Results were as follows : Hypothesis 1. The actually experienced life events were expected to be higher in the experimental group than in the control group, but they did not show the significant difference between the groups.（ p >0.05) Thus hypothesis 1 was rejected. Hypothesis : 2. The stress scores were expected to be higher in the experimental group than in the control group, and also did show the significant difference between the groups ( p< 0.05）. Therefore hypothesis 2 was supported. Hypothesis 3. The non-effective coping behavior were expected to be higher in the experimental group than in the control group, and also did show the significant difference between the two groups(p < 0.001). Also hypothesis 3 was supported. Hypothesis 4 . The higher stress score groups (above 250 LCU ) were expected to utilize non.effective coping method more frequently than in the lower stress score groups (below 249 LCU ), and not only they showed high in utilizing non-effective coping method but also showed high in utililzing effective coping method. Thus hyphothesis 4 was partially supported. (p < 0.001) The following are drawn out based on the result of this study that the stress scores were higher, and more utilized non-effective coping method in the emotionally disturbances than in the emtionally healthies.

• The Journal of Internal Korean Medicine
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• v.16 no.1
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• pp.1-16
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• 1995

This study was done in order to investigate the etiology and pathology of dementia in the variety literature. Dementia in elderly persons(above the age of 60) mainly classfied Alzheimer disease and Cerebral vascular dementia. The results were as follows: 1. Dementia patients have abnormal mental function, who have no mental weakness but defects of memory, verbal disturbance, behavior disturbance and loss of intellectual function. 2. Dementia regard as 'me-beng(?病)', 'jeon-gwang(癲狂)', and 'heo-ro(虛勞)' in oriental medicine and the symptom is a silence with no response, mixing, a crying or a laugh, a stranger behavior and a amnesia; disturbances of speech, emotion, behavior. 3. Dementia caused by Alzheimer disease, Multi infarct dementia, Parkinson's disease, sequelae of acute CO poisoning, head injury and alcoholism(occidental medically) and the 'Dam(痰) and Damhwa(痰火), weakness of heart and spleen(心脾虛) caused by pent up anger of seven emotions(七情鬱結), the weakness of liver and kidney(肝腎不足)(oriental medically). 4. The causes of Alzheimer disease are various; a heredity factor, a morphological factor of brain tissues, a psychological factor and a biochemical factor (occidental medically) ; the 'Dam(痰) and Damhwa(痰火) caused by weakness of the internal organs and disturbance of the emotions(oriental medically). 5. Cerebral vascular dementia caused by loss of the certain cerebral neurons and oriental medically caused by obstruction of 'dam(痰)' or 'eo heul(瘀血)'. It is recommended that further study of many sided investigations, specially against a weakness of spiritual functions and a certain neurotoxin in the future.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.495-506
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• 2021

In this study, using a continuous behavior measurement technique, the short-term behavioral responses and tolerance limits of red seabream Pagrus major fingerlings to sudden exposure to low salinity in a controlled environment were observed. The activity of the fingerlings suddenly exposed to 21.4, 17.3, and 9.8 psu increased temporarily at the initial exposure to show irregular swimming behavior, but then recovered a stable activity pattern through rapid salinity adaptation. However, the organisms suddenly exposed to 7.3 and 4.3 psu could not withstand the salinity stress, and their swimming behavior was severely disturbed and all individuals died within 48 hours. The findings suggest that red seabream underwent a temporary salinity stress process at the beginning of the exposure to concentrations of 10.0 psu or higher. At these concentrations, osmotic control was possible within at least 11 hours, so stable metabolic activity was also possible. However, organisms suddenly exposed to concentrations below 5.0 psu exceeded the tolerance to low salinity and the sublethal limit. In red seabream exposed to this concentration range, severe behavioral and metabolic disturbances were observed, and death was observed due to osmotic control failure. In conclusion, a salinity range of 5.0 to 10.0 psu can be predicted to correspond to a concentration range in which the osmotic control ability of the red seabream fingerlings is lost, and sub-lethal reactions occur.