• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.67-69
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• 2007

PMSM (Permanent Magnet Synchronous Motor) current control is a most inner loop of electromechanical driving systems and it plays a foundation role in the hierarchy's control loop of several mechanical machine systems. In this paper, a simple RMRAC control scheme for the PMSM is proposed in the synchronous frame. In the synchronous current model, the input signal is composed of as a calculated voltage by adaptive laws and system disturbances. The gains of feed-forward and feed-back controller are estimated by the proposed e-modification methods respectively, where the disturbances are assumed as filtered current tracking errors. After the estimation of the disturbances from the tracking errors, the corresponding voltage is fed forward to control input to compensate for the disturbances. The proposed method is robust to high frequency disturbances and has a fast dynamic response to time varying reference current trajectory. It also shows a good real-time performance duo to it's simplicity of control structure. Through the simulations considering several cases of external disturbances and experimental results, efficiency of the proposed method is verified

• Structural Engineering and Mechanics
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• v.29 no.5
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• pp.489-504
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• 2008

In piezoelectric flexible structures, the contribution of vibration modes to the dynamic response of system may change with the location of piezoelectric actuator patches, which means that the ability of actuators to control vibration modes should be taken into account in the development of modal reduction model. The spatial $H_2$ norm of modes, which serves as a measure of the intensity of modes to system dynamical response, is used to pick up the modes included in the reduction model. Based on the reduction model, the paper develops the state-space representation for uncertain flexible tructures with piezoelectric material as non-collocated actuators/sensors in the modal space, taking into account uncertainties due to modal parameters variation and unmodeled residual modes. In order to suppress the vibration of the structure, a dynamic output feedback control law is designed by imultaneously considering the conflicting performance specifications, such as robust stability, transient response requirement, disturbance rejection, actuator saturation constraints. Based on linear matrix inequality, the vibration control design is converted into a linear convex optimization problem. The simulation results show how the influence of vibration modes on the dynamical response of structure varies with the location of piezoelectric actuators, why the uncertainties should be considered in the reductiom model to avoid exciting high-frequency modes in the non-collcated vibration control, and the possiblity that the conflicting performance specifications are dealt with simultaneously.

• Advances in aircraft and spacecraft science
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• v.2 no.3
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• pp.345-365
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• 2015

This paper focuses on the design, fabrication, testing and analysis of a novel load-bearing element with energy dissipation capability. A single element comprises two von-Mises trusses (VMTs), which are sandwiched between two plates and connected to dashpots that stroke as the VMTs cycle between stable equilibrium states. The elements can be assembled in-plane to form a large plate-like structure or stacked with different properties in each layer for improved load-adaptability. Also introduced in the elements are pre-loaded springs (PLSs) that provide high initial stiffness and allow the element to carry a static load even when the VMTs cannot under harmonic disturbance input. Simulations of the system behavior using the Simscape environment show good overall correlation with test data. Good energy dissipation capability is observed over a frequency range from 0.1 Hz to 2 Hz. The test and simulation results show that a two layer prototype, having one soft VMT layer and one stiff VMT layer, can provide good energy dissipation over a decade of variation in harmonic load amplitude, while retaining the ability to carry static load due to the PLSs. The paper discusses how system design parameter changes affect the static load capability and the hysteresis behavior.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1655-1662
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• 2018

This paper studies the magnetic fields between the power lines which are finite length and other ones which are infinitely long around the first tower in the proximity of the power transformers. They will be used as a source of disturbance applied to the power line. The method applied in this study was gradual; develop the theoretical formulation of the magnetic fields of these lines which are finite length and other ones which are infinitely long, examine the effects of different couplings between the different neighboring lines and the distribution transformers on behavior of magnetic fields. The method also focused on the experimental results analyzing the magnetic fields which will be used as a source applied to the auditory implants EMC. The theoretical and experimental results were compared and discussed for three power lines (90kV, 150kV and 225kV) near the power station, and it proved the effect of these substations on the simulated and measured results of the magnetic field. The maximum intensities of magnetic fields measured at the height of 1m from the ground for the circuit of three lines close to each substation were significantly lower than the ICNIRP reference levels for occupational and non occupational exposures.

• Journal of the Korean society of biological therapies in psychiatry
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• v.24 no.3
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• pp.142-155
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• 2018

Insomnia in patients with hematopoietic stem cell transplantation(HSCT) has been underdiagnosed and undertreated. This study reviewed the frequency, characteristics, physical and psychological effects, and treatments of insomnia in HSCT patients to highlight clinical importance in this specialized population. Furthermore, the authors intended to suggest a model that would conceptualize insomnia in the context of HSCT. In the pre-transplant period, about half of patients with HSCT suffered from sleep disturbance. A substantial number of patients experienced distressing insomnia during the HSCT procedure and recovered to the level of the pre-transplant period. However, sleep disruption could be a chronic symptom in HSCT survivors and could negatively impact quality of control, cancer-related fatigue(CRF), immune function, and psychological distress. The 3P's model(Predisposing, Precipitating, Perpetuating) explains insomnia in cancer population and could be also relevant to HSCT patients with specific consideration of CRF, graft-versus-host diseases, specific properties of hematological disease, and protective isolated milieu. Effective treatment of insomnia in HSCT includes non-pharmacological(e.g., cognitive behavioral therapy, environmental modification) and pharmacological interventions. The decision of pharmacological treatment should be based on the issue of safety due to high risk of potential drug-drug interactions. Screening, treatment, and further research of insomnia in HSCT patients using validated subjective and/or objective measures are warranted.

• Journal of IKEEE
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• v.26 no.4
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• pp.590-595
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• 2022

When a train is delayed because of a disturbance, the time interval deviation between successive trains increases, and high frequency metro lines can become unstable. Thus, it is necessary to control the traffic regularity to prevent any such instability. In this paper, we propose a simple but effective traffic regulation algorithm that gurantees system stability. In the proposed method, the control algorithm for running time is designed using a discrete traffic model where control input is determined from a linear combination of departure time deviations and control input of the preceding train to ensure an optimal time interval between successive trains. The results of the computer simulation are also given to demonstrate the validity of the proposed algorithm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.7
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• pp.851-856
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• 2013

Recently, as the tactical environment has changedto one of network-centric warfare, where all components are connected through a network, much emphasis has been placed on the use of an artificial satellite for achieving high communication speeds. To provide a high-quality artificial satellite link, stabilization is very important in a platform. Previous stabilization control techniques used PI control, which is commonly used for vessels. However, for ground terminals that require a higher communication speed, the antenna should move faster to track an artificial satellite within a short period of time. Moreover, the terminals must be equipped with proper sensors and algorithms so that they can detect and compensate for external disturbances while tracking the artificial satellite. In this study, through the analysis of the dynamic model of an antenna system, a stabilization algorithm for ground terminals was proposed;this algorithm shows high isolation performance in the low-frequency range and includes $PI^2$ control.

• Journal of the Korean Institute of Landscape Architecture
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• v.26 no.3
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• pp.66-77
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• 1998

The purpose of this study is on identifying real condition of naturalized plants in urban green space. For this, Chollabak-do region was selected for case study. The occurring frequency and distribution status was investigated by field survey. The area of green open space, level of management and passed years after construction etc, were analized to identify the influence on occurrence of naturalized plants. The result is as follows: 1. In 18 sites, 145 taxa as weed species including naturalized plants were occurred. Average No. of occurring taxa is 22.7. Two families of plants, Graminae and compositae charged the most part. Also the rate of naturalized plant among them is 29.7%. 2. Naturalized species showing high occurring rate are 14 taxa of compositae, 5 taxa of Gramineae, Leguminosae and 4 taxa of cruciferae. These plants of previous four somatic polymorphism among all the naturalized plants. 3. The taxa number of naturalized plants were reducedby intensive management. But the rate of naturalized plants in extensively managed area was relatively lower than intensively managed one. Naturalizd plants were widely distributed in most of urban green space with being cognitioned as whole weed. 4. In origin of naturalized plants, the taxa from north America were 16 and the taxa from Europe were 16. Therefore the rate originated from north America and Europe charged high part as 68.2%. The rate of Annual, Biennial and Perennial were each 78.7%, 21.3%. The alternative of management for control aganist disturbance by Annual & Biennial required. 5. Multi-relations analysis shows 0.81 which is the relatively high interralation between the number of emerged axa and that of naturalized ones. 6. The number of naturalized species has no relation to the lapse of years after construction of open-space. Especially it was identified that weed control in the beginning of construction is very important. On the other hand the relation between Ys and Xp was Ys=1.784Xp+4.646.

• The Journal of Internal Korean Medicine
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• v.19 no.1
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• pp.168-184
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• 1998

Clinical Observation was made on 120 Cases of CVA that were confirmed through brain CT of Oriental Medical hospital of Se-Myung University from July in 1997 to June in 1998. 1. The CVA cases were classified into the following kinds : cerebral infarction, cerebral hemorrhage, subarachnoid hemorrhage(SAH), and the greatest in number among them were the cases of cerebral infarction. 2. The most cases were 50 of age in all cases, in cerebral infarction were over 70 of age. There is no significant difference in the frequency of strokes between the male and female. the ratio was 1.07 : 1. 3. The frequency of strokes seems to have no relation to month and season. 4. The course of entering hospital, most patients visited this hospital directly(not through any other hospital) within 24hours. 5. The first attack was noted in 80.8%, the recurrance attack in 19.2% and the cerebral infarction had high recurrance ratio compared with cerebral hemorrhage. 6. The average duration of hospitalization was 25.2 days. 7. The most ordinary preceding disease was hypertension. 8. The common symptoms were motor disturbance and dysphasia. 9. The most frequent location of the lesion in cerebral infarction was parietal lobe, in cerebral hemorrhage was basal ganglia. 10. According to electrocardiography findings, abnormality was noted in cerebral infarction more than cerebral hemorrhage, subarachnoid hemorrhage. 11. The hypercholesterolemia and hypertriglyceridemia were found more frequently in cerebral infarction than cerebral hemorrhage, subarachnoid hemorrhage. 12. The average time to start physical theraphy was 7.76 days after admission. 13. The most common complications were pneumonia and bed sore.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.376-379
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• 2006

Reaction Wheel Assembly (RWA) is one of the major disturbance sources that have influence upon the Line of Sight (LOS) of payload. A micro-vibration induced by RWA is propagated through the satellite structure and decrease the LOS stability performance of payload. This effect shall be analyzed through the jitter analysis. If a requirement or specification of payload jitter level is found to be not satisfied according to the jitter analysis campaign, some modification or redesign should be done on the satellite structure or a couple of isolator should be attached on the RWA interface in order to reduce the transmitted vibration level of RWA. The purpose of ???RWA isolator test? is to roughly evaluate the performance of vibration suppression level with a passive RWA isolator made of rubber. For this test, actual RWA is used as a vibration source and a couple of cube-shaped rubber mount designed for satellite is used as a passive isolator. There may be several considerations in order to accommodate RWA isolator to spacecraft such as not only vibration reduction performance but also thermal conduction problem, mechanical size, RWA alignment problem, etc. But in this report the feasibility of RWA isolator is analyzed only in a vibration suppression point of view. As a result, high frequency vibration of RWA above 50Hz is perfectly attenuated with isolators, however, first harmonic components below 50Hz became larger due to the additional low frequency resonance modes of roll, pitch, yaw rigid body motion of RWA+bracket.