• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.157-164
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• 2016

The paper studies a comparison analysis of semi-active control strategies for a Macpherson strut type suspension system consisting of MR(magneto-rheological) damper. As a first step, in order to formulate governing, a dynamic full model of a Macpherson strut is developed considering the kinematics. The nonlinear equation of motion of the strut is then linearized around the equilibrium point. A new adaptive moving sliding model controller is developed for fast response of the system. A newly proposed adaptive moving sliding mode control strategy is then compared with conventional sliding mode controller and skyhook controller. The comparison is made for two different types of road inputs; bump and random road profiles showing superior vibration control performance in time and frequency domains.

• The Korea Journal of Herbology
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• v.20 no.4
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• pp.83-94
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• 2005

Objectives : The present study attempted to reveal the effects of Morindae Radix extracts on the sciatic nerve neurectomized osteoporotic ddy mice model. Methods : Thickness of hind limbs and their differences, absolute and relative tibia weight and thickness, bone failure load, bone mineral density (BMD), histomorphometrical index, serum osteocalcin level, tibia calcium and phosphorus contents were monitored. Results : In sciatic neurectomized mice, thickness of hind limb, absolute and relative weights, thickness, failure loads, BMD of tibia, trabecular bone volume (TBV), thickness of trabecular bone and cortical bone thickness, length were significantly decreased. However, these changes of those dose-dependently reduced in MR extract-dosing group. Conclusions : it is considered that MR extracts have some favorable effect to prevent, the osteoporosis induced by sciatic neurectomy. However, the exact mechanism and the possibility of MR extract were remains unknown. In addition, the potential toxicity of these MR extracts were also unknown. So the further studies were needed about toxicological and pharmacological aspects.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.2
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• pp.135-144
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• 2009

Fuzzy hybrid control technique with a smart tuned mass damper(STMD) was proposed in this study for the suppression of wind-induced motion of a tall building. To develop the effective control algorithm for a STMD, skyhook and groundhook control algorithms were employed. Usually, skyhook controller can effectively reduce STMD motion and groundhook controller shows good control performance for the reduction of building responses. In this study, fuzzy hybrid controller, which can determine an optimal weighting factor for combining two controllers in real time, was developed to improve the control performance of conventional hybrid controller using weighted sum approach. A 76-story office building was used as an example structure to investigate the performance of the proposed controller. A magnetorheological(MR) damper was used to develop a STMD and the control performance of STMD was evaluated comparing with the passive and active TMD. The numerical studies show that the control effectiveness of a STMD is significantly superior to that of the conventional TMD. It is also shown that fuzzy hybrid controller can effectively adjust skyhook and groundhook control algorithms and reduce both responses of STMD and building.

• Journal of Chest Surgery
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• v.15 no.1
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• pp.53-60
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• 1982

M-mode echocardiographic studies of left ventricular function in mitral valve disease were evaluated in 19 surgically treated patients before and one year after operation (mean 12.7 months). Twelve patients had mitral stenosis (MS) and seven patients had mitral regurgitation (MR). Before surgery, average end-diastolic and end systolic dimensions (EDD, and ESD) and left atrial dimension were significantly greater than normal in subject with MR. After surgery, EDD fell significantly from $66.5{\pm}8.4$ (SD)mm to $52.7{\pm}6.3$mm (P 0.01) at the time of late follow up study; ESD fell significantly from $46.5{\pm}9.7$mm to $36.4{\pm}8.6$ (P 0.05) on early follow up study; left atrial dimension fell significantly from $60.5{\pm}6.8$mm to $48.1{\pm}7.2$mm (P 0.01) at the time of the late follow up study. In patients with MS, EDD and ESD were normal and did not change significantly at any time after surgery. The left ventricular ejection fraction (E.F.) was normal in both groups. preoperatively([MR: $64.2{\pm}15.1$, MS: $65.7{\pm}12.3$). After surgery, E.F. did not change significantly at any time after surgery in both groups, but de-creased from $64.2{\pm}15.1$% to $59.5{\pm}11.2$% in MR patients at the time of early follow up study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.139-145
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• 2018

An outrigger system is used widely to increase the lateral stiffness of high-rise buildings, resulting in reduced dynamic responses to seismic or wind loads. Because the dynamic characteristics of earthquake or wind loads are quite different, a smart vibration control system associated with an outrigger system can be used effectively for both seismic and wind excitation. In this study, an adaptive smart structural control system based on an outrigger damper system was investigated for the response reduction of multi-hazards, including seismic and wind loads. A MR damper was employed to develop the smart outrigger damper system. Three cities in the U.S., L.A., Charleston, and Anchorage, were used to generate multi-hazard earthquake and wind loads. Parametric studies on the MR damper capacity were performed to investigate the optimal design of the smart outrigger damper system. A smart control algorithm was developed using a fuzzy controller optimized by a genetic algorithm. The analytical results showed that an adaptive smart structural control system based on an outrigger damper system can provide good control performance for multi-hazards of earthquake and wind loads.

• Journal of Biomedical Engineering Research
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• v.28 no.5
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• pp.636-646
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• 2007

Adequate postural control depends on the spatial and temporal integration of vestibular, visual, and somatosensory information. Especially, the musculoskeletal function is essential to maintain the postural control. The experimental studies was performed on the muscular activities in the lower extremities during maintaining and moving exercises on an unstable platform with Magneto Rheological(MR) dampers. The unstable platform of the developed system was controlled by electric currents to the MR dampers. A subject executed the maintaining and moving exercises which are presented through the display monitor. The electromyographies of the eight muscles in lower extremities were recorded and analyzed in the time and the frequency domain: the muscles of interest were rectus femoris(RF), biceps femoris(BF), tensor fasciae latae(TFL), vastus lateralis(VL), vastus medialis(VM), gastrocnemius(Ga), tibialis anterior(TA), Soleus(So). The experimental results showed that the muscular activities differed in the four moving exercises and the nine maintaining exercises. For the anterior-posterior pattern, the TA showed highest activities; for the left-right pattern, the TFL; for the 45, $-45^{\circ}$ pattern, the TFL and TA. Also, the rate of the increase in the muscular activities were affected by the condition of the unstable platform with MR dampers for the maintaining and moving exercises. The experimental results suggest that the choice of different maintaining and moving exercises could selectively train different muscles in various intensity. Futhermore, the findings suggested that the training using this system can improve the ability of postural control.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.196-201
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• 1995

Chemo- and numerical taxonomic studies on the isolate SL-387 producing novel aminopeptidase M inhibitors MR-387A and B were carried out The genus of the isolate was determined as Streptomyces by cultural and morphological data and chemical indices. Forty one taxonomic unit characters were tested for determining the species of the isolate, and the data were analyzed numerically using a computer program as called TAXON. The isolate was best matched to Streptomyces neyagawaensis in the major cluster 18 of Streptomyces with $S_{SM}$ value of 75.67%. On the base of chemotaxonomic data and TAXON analysis, the isolate SL-387 was identified to be a member of Streptomyces neyagawaensis.

• The Journal of the Korea Contents Association
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• v.19 no.6
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• pp.412-417
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• 2019

This study was proposed to investigate vital signs in subjects undergoing high magnetic field (3T) MR imaging for provide basic data on causes of claustrophobia as few previous studies were conducted on this special issue. Vital signs of 104 patients were monitored before and during the clinically indicated MR examinations to identify any relationship between MR scanning and the vital signs. An increase of systolic, diastolic blood pressure and pulse pressure were observed. However, they were not statistically significant(p>0.05), which meant the vital signs measured before and during the MRI scanning showed no significant change. This study is considered to be meaningful basic data for analyzing the links between vital sign fluctuations on claustrophobia during routine clinical MR examinations.

• Korean Journal of Radiology
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• v.1 no.3
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• pp.152-158
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• 2000

Objective: The purpose of this study was to compare the effectiveness of MR urography (MRU) with that of ultrasonography (US) in the evaluation of urinary tract when this failed to opacify during excretory urography (EXU). Materials and Methods: Twelve urinary tracts in 11 patients were studied. In each case, during EXU, the urinary system failed to opacify within one hour of the injection of contrast media, and US revealed dilatation of the pelvocalyceal system. Patients underwent MRU, using a HASTE sequence with the breath-hold technique; multi-slice acquisition was then performed, and the images were reconstructed using maximal intensity projection. Each set of images was evaluated by three radiologists to determine the presence, level, and cause of urinary tract obstruction. Results: Obstruction was present in all twelve cases, and in all of these, MRU accurately demonstrated its level. In this respect, however, US was successful in only ten. The cause of obstruction was determined by MRU in eight cases, but by US in only six. In all of these six, MRU also successfully demonstrated the cause. Conclusion: MRU is an effective modality for evaluation of the urinary tract when this fails to opacify during EXU, and appears to be superior to US in demonstrating the level and cause of obstruction.

• Korean Journal of Radiology
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• v.1 no.1
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• pp.5-10
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• 2000

Objective: To describe the neuroradiologic findings of primary antiphospholipid antibody syndrome (PAPS). Materials and Methods: During a recent two-year period, abnormally elevated antiphospholipid antibodies were detected in a total of 751 patients. In any cases in which risk factors for stroke were detected - hypertension, diabetes mellitus, hyperlipidemia, smoking, and the presence of SLE or other connective tissue diseases - PAPS was not diagnosed. Neuroradiologic studies were performed in 11 of 32 patients with PAPS. We retrospectively reviewed brain CT (n = 7), MR (n = 8), and cerebral angiography (n = 8) in 11 patients with special attention to the presence of brain parenchymal lesions and cerebral arterial or venous abnormalities. Results: CT or MR findings of PAPS included nonspecific multiple hyper-intensity foci in deep white matter on T2-weighted images (5/11), a large infarct in the territory of the middle cerebral artery (4/11), diffuse cortical atrophy (2/11), focal hemorrhage (2/11), and dural sinus thrombosis (1/11). Angiographic findings were normal (5/8) or reflected either occlusion of a large cerebral artery (2/8) or dural sinus thrombosis (1/8). Conclusion: Neuroradiologic findings of PAPS are nonspecific but in young or middle- aged adults who show the above mentioned CT or MR findings, and in whom risk factors for stroke are not present, the condition should be suspected.