• Journal of IKEEE
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• v.25 no.3
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• pp.548-555
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• 2021

This paper outlines the basic concepts, approaches and research trends of fault diagnosis and fault tolerant control applied to industrial processes, facilities, and motor drives. The main role of fault diagnosis for industrial processes is to create effective indicators to determine the defect status of the process and then take appropriate measures against failures or hazadous accidents. The technologies of fault detection and diagnosis have been developed to determine whether a process has a trend or pattern, or whether a particular process variable is functioning normally. Firstly, data-driven based and model-based techniques were described. Secondly, fault detection and diagnosis techniques for industrial processes are described. Thirdly, passive and active fault tolerant control techniques are considered. Finally, major faults occurring in AC motor drives were listed, described their characteristics and fault diagnosis and fault tolerant control techniques are outlined for this purpose.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2224-2236
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• 2014

The performance of an isolated high voltage full bridge converter is improved using a voltage doubler. In a conventional high voltage full bridge converter, the diode of the transformer secondary voltage undergoes a voltage spike due to the leakage inductance of the transformer and the resonance occurring with the parasitic capacitance of the diode. In addition, in the phase shift control, conduction loss largely increases from the freewheeling mode because of the circulating current. The efficiency of the converter is thus reduced. However, in the proposed converter, the high voltage dual converter consists of a voltage doubler because the circulating current of the converter is reduced to increase efficiency. On the other hand, in the proposed converter, an input current is distributed when using parallel input / serial output and the output voltage can be doubled. However, the voltages in the 2 serial DC links might be unbalanced due to line impedance, passive and active components impedance, and sensor error. Considering these problems, DC injection is performed due to the complementary operations of half bridge inverters as well as the disadvantage of the unbalance in the DC link. Therefore, the serial output of the converter needs to control the balance of the algorithm. In this paper, the performance of the conventional converter is improved and a balance control algorithm is proposed for the proposed converter. Also, the system of the 1.5[kW] PCS is verified through an experiment examining the operation and stability.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.203-209
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• 2020

A hybrid mount featuring rubber element and piezoelectric actuator is devised to reduce vibration when starting a vehicle engine. As a first step, a passive mount adopting rubber element is manufactured and its dynamic characteristics are experimentally evaluated. After evaluating dynamic characteristics of the manufactured inertial piezoelectric actuator, the proposed hybrid mount is then established by integrating the piezoelectric actuator with the rubber element for performance improvement at non-resonant high frequencies. A mathematical model of the established active vibration control system is formulated and expressed in the state space form. Subsequently, sliding mode controller (SMC) is designed to attenuate the vibration transmitted from the base excitation. Finally, control performances of the proposed hybrid mount are evaluated such as transmissibility in frequency domain and time responses.

• Journal of Korean Academy of Nursing
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• v.29 no.3
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• pp.665-678
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• 1999

Stroke is a major cause of death and long-term disability. Because muscle weakness is one of the most prominent consequences of stroke, it was considered important to determine whether exercise in order to improve muscle strength and range of motion could have an effect in limiting the learned disuse of the affected side. The purpose of the study was to identify the effects of an 8 week rehabilitation program on physical and cognitive ability in stroke patients. A total of 18 patients who were admitted to the oriental medicine unit of a K medical center in Seoul were recruited : ten for the experimental group and eight for the control group. The rehabilitation program consisted of three level's of active and passive exercises for prevention of muscle contracture and at range of motion. Muscle strength, flexibility of the upper and lower extremity, perceived balance, functional independence, depression, and quality of life for the two groups were compared at the pretest and 4 and 8 weeks after the rehabilitation program. The results are as follows : 1) When measuring muscle strengths of shoulder abduction and elbow flexion, hip flexion and knee extensor, ankle dorsi-flexor and muscle strength of knee flexor. Muscle strength of knee flexor for the experimental group was significantly higher than the comparison group at the 4 weeks. 2) Muscle strength and flexibility of the ankle dorsi -flexor for the experimental group was significantly better than for the control group at 8 weeks. 3) Functional independence, perceived balance, and Tinetti balance for the experimental group as measured at 4 and 8 weeks were better than for the control group. Also, there were changes over time in physical balance and functional ability, but there was no significant differences between the groups. 4) The experimental group showed a higher quality of life and lower depression than the control group at 8 weeks. 5) Muscle strength and flexibility of ankle dorsi -flexor were significantly changed over time and an interaction between group and time. The findings suggested that the rehabilitation program would improve the physical and psychological status of the stroke patients. Thus, the gains in actual or perceived ability to perform physical activities was marked.

• Smart Structures and Systems
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• v.21 no.3
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• pp.287-303
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• 2018

Applications of energy harvesting from mechanical vibrations is becoming popular but the full potential of such applications is yet to be explored. This paper addresses this issue by considering an application of energy harvesting for the dual objective of serving as an indicator of structural health monitoring (SHM) and extent of control. Variation of harvested energy from an undamaged baseline is employed for this purpose and the concept is illustrated by implementing it for active vibrations of a pipe structure. Theoretical and experimental analyses are carried out to determine the energy harvesting potential from undamaged and damaged conditions. The use of energy harvesting as indicator for control is subsequently investigated, considering the effect of the introduction of a tuned mass damper (TMD). It is found that energy harvesting can be used for the detection and monitoring of the location and magnitude of damage occurring within a pipe structure. Additionally, the harvested energy acts as an indicator of the extent of reduction of vibration of pipes when a TMD is attached. This paper extends the range of applications of energy harvesting devices for the monitoring of built infrastructure and illustrates the vast potential of energy harvesters as smart sensors.

• Korean Journal of Veterinary Research
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• v.43 no.2
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• pp.255-261
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• 2003

The antigenicity of nonspecific immunostimulator BARODON$^{(R)}$, a newly developed drug, was investigated by tests for passive cutaneous anaphylaxis (PCA) and active systemic anaphylaxis (ASA) in mice and guinea pigs. In ASA test using guinea pigs, there were no significant clinical symptoms in all individuals of low(0.3%) and high(3%) dose of both groups treated with only BARODON$^{(R)}$ and cotreated with BARODON$^{(R)}$ and adjuvant group. In PCA test, blue spots of Evan's were observed from $2^6$ to $2^{10}$ in homologous group and from $2^2{\sim}2^5$ dilution rate in heterologous group of BSA treated positive control group. However, intradermal sensitization with antiserum obtained from low (0.3%) and high (3%) dose of BARODON$^{(R)}$ only treatment group and treated-with-adjuvant group, followed by intravenous injection of respective antigen and Evan's blue mixture (1:1) showed no blue spot observed. In conclusion, BARODON$^{(R)}$, as showed in ASA and PCA test, did not cause anaphylatic shock when treated 3 and 10 times higher than clinically intended dose, nor induce IgE, so that might not have antigenic properties in mice and guinea pigs.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.5
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• pp.1118-1126
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• 2007

The purpose of this study was to examine the anti allergic effect in vivo and in vitro, and to observe single and four weeks repeated toxicity in mice of Bangpung-galgeun-tang (BGT). We investigated anti DNP IgE-mediated passive cutaneous anaphylaxis in rodents and compound 48/80-induced active systemic anaphylatic shock in mice after oral administration with BGT of 0.4 g/kg and 0.8 g/kg for 8 days, and also examined MTT assay, ${\beta}-hexosaminidase$ activity, IL-4 and $TNF-{\alpha}$ from RBL-2H3 and $TNF-{\alpha}$ from Raw264.7 after pre-treatment with BGT of 0.25 mg/ml, 0.5 mg/ml, 1 mg/ml and 2 mg/ml. To ascertain safety and toxicity of BGT, we divided into single and four weeks repeated administration test. In single test, three groups were administrated different dosages and routes (2 g/kg/i.p., 4 g/kg/i.p. and 15 g/kg /p.o.) of BGT, and in four weeks repeated test, 0.8 g/kg BGT was administrated. Control groups were administrated with only saline according to on Korean Food and Drug Administration, respectively. We observed attentively motality, abnormal clinical sign, body weight change, organ weight, AST and ALT of mice after BGT administration. BGT inhibited passive cutaneous anaphylaxis and active systemic anaphylatic shock by oral administration. All the concentrations of BGT from 0.25 to 2 mg/ml didn't have an effect on cell viability and cytotoxicity. In RBL-2H3, ${\beta}-hexosaminidase$ release, IL-4 and $TNF-{\alpha}$, and in Raw264.7, $TNF-{\alpha}$ were significantly reduced by treated all concentrations of BGT. During toxicity experiment period, there was no difference in body weight change, organ weight, AST and ALT among different dose groups. Death were found 3 mice from day 2 to day 3 in single test i.p. group. (2 g/kg, 4 g/kg). Several individuals of single test i.p. group were observed that decreased locomotor activity, exophthalmos, bloodshot eyes, loss of eyesight and so on in early period after administration. But there was no difference in clinical signs among p.o. group. These results indicate that BGT have inhibition effects on allergy and suggest that no observable effect level of the test orally administration was considered to be more than 2 g/kg in mice under the conditions employed in this study.

• Journal of the Korea Convergence Society
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• v.11 no.8
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• pp.237-245
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• 2020

The purpose of this study was to identify the relationship between stress coping, spouse support, intentional rumination, and post-traumatic growth of subjects who experienced traumatic events hysterectomy. The subjects collected from 67 women who had hysterectomy were analyzed using t-test, ANOVA and multiple regression analysis. As a result of this study, the post-traumatic growth of the subjects was passive coping (r=0.27, p=.026), active coping (r=0.34, p=.004), and intentional reflection (r=0.46, p<.001)), and passive coping was positively correlated with active coping (r=0.74, p<.001). Regression analysis to identify factors affecting on the post-traumatic growth of women with hysterectomy showed that intentional rumination was the significant factor(β = 0.42, p <.001). and their total explanatory power was 26% (F = 8.68, p < .001). Therefore, results of this study, in order to promote post-traumatic growth of subjects with hysterectomy, an intervention program is needed to increase the intentional rumination to effectively face the trauma they suffer.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.4
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• pp.247-254
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• 2013

In this paper, dynamic response analysis of a heave compensation system is performed for offshore drilling operations based on multibody dynamics. With this simulation, the efficiency of the heave compensation system can be virtually confirmed before it is applied to drilling operations. The heave compensation system installed on a semi-submersible platform consists of a passive and an active heave compensator. The passive and active heave compensator are composed of several bodies that are connected to each other with various types of joints. Therefore, to carry out the dynamic response analysis, the dynamics kernel was developed based on mutibody dynamics. To construct the equations of motion of the multibody system and to determine the unknown accelerations and constraint forces, the recursive Newton-Euler formulation was adapted. Functions of the developed dynamics kernel were verified by comparing them with other commercial dynamics kernels. The hydrostatic force with nonlinear effects, the linearized hydrodynamic force, and the pneumatic and hydraulic control forces were considered as the external forces that act on the platform of the semi-submersible rig and the heave compensation system. The dynamic simulation of the heave compensation system of the semi-submersible rig, which is available for drilling operations with a 3,600m water depth, was carried out. From the results of the simulation, the efficiency of the heave compensation system were evaluated before they were applied to the offshore drilling operations. Moreover, the calculated constraint forces could serve as reference data for the design of the mechanical system.

• Journal of Hydrogen and New Energy
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• v.28 no.1
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• pp.113-119
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• 2017

An investigation on aerodynamic performance of a highly-loaded axial fan has been conducted to find the effects of tip injection and casing groove on aerodynamic performance in this study. Three-dimensional Reynolds-averaged Navier-Stokes equations with $k-{\varepsilon}$ turbulence model were used to analyze the fluid flow in the fan with Fluid-Structure Interaction (FSI) analysis. The hexahedral grid was used to construct computational domain, and the grid dependency test drew the optimal grid system. FSI analysis was also carried out to predict the deformation of rotor and stator blades, and the effect of deformation on the aerodynamic performance of axial fan was analyzed compared to the performance predicted without FSI analysis.