• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.302-306
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• 2012

Bacterial cellulose based actuator with large displacement was developed for biomimetic robots. Bacterial cellulose has 3D nanostructure with high porosity which was composed of the nanofibers. Freeze dried bacterial cellulose was dipped into ionic liquid solution such as 1-butyl-3-methylimidazolium(BMIMCl) to enhance the actuation performance due to increase the ionexchange capacity and ionic conductivity. And Poly(3,4-ethylenedioxythiophene)-poly (styrnenesulfonate)(PEDOT:PSS) was used for the electrodes of both side of bacterial cellulose actuator by dipping and drying method. The FT-IR and XRD were conducted to examine the electrochemical changes of developed bacterial cellulose actuator. The biomimetic caudal fin was designed using bacterial cellulose actuator and PDMS to verify the possibility for biomimetic robot. The step and harmonic response were conducted to evaluate the performance of developed biomimetic actuator.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.12
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• pp.691-700
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• 1999

This paper proposes a novel switching strategy of 1Mvar STATCON using cascade multilevel H-bridge inverter(HBI) for FACTS application. To control the reactive power instantaneously, the d-q dynamic system model is described and analyzed. A single pulse pattern based on the SHEM(Selective Harmonic Elimination Method) technique is determined from the look-up table to reduce the line current harmonics and a rotating fundamental frequency switching scheme is presented to adjust the DC voltage of each inverter capacitor at the same value. So the voltage unbalance problem between separately DC bus voltage is improved by using the proposed switching scheme. As a result, the presented inverter configuration not only reduces the system complexity by eliminating the isolation at the AC input side transformer but also improves the dynamic response to the step change of reactive power.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.138-139
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• 2017

This paper describes the design and implementation of a trigger circuit which can be series connected with main pulse circuit for a xenon flash lamp driver. For generating high voltage, the trigger circuit is designed as an inductive energy storage pulsed power modulator with 2 state step-up circuit consisting of a boost converter and a flyback circuit. In order to guarantee pulse width, a resonant capacitor on the output side of the flyback circuit is designed. This capacitor limits the output voltage to protect the flyback switch. In addition, to protect another power supply of xenon flash lamp driver from trigger pulse, the high voltage transformer which can carry the full current of main pulse is designed. To verify the proposed design, the trigger circuit is developed with the specification of maximum 23 kV, 0.6 J/pulse output and tested with a xenon flash lamp driver consisting of a main pulse circuit and a simmer circuit.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.402-410
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• 2008

Single-walled carbon nanotubes (SWCNTs) were currently produced together with some contaminants such as a metallic catalyst, amorphous carbon, and graphitic nanoparticles, which should be sometimes purified for their applications. This study aimed to develop efficient, scalable purification processes but less harmful to SWCNTs. We designed three-step purification processes: acidic treatment, surface functionalization and soxhlet extraction, and heat treatment. During the soxhlet extraction using tetrahydrofuran, specifically, carbon impurities could be easily expelled through a glass thimble filter without any significant loss of CNTs. Finally, SWCNTs were left as a bulky paper on the filter through membrane filtration. Vertically aligned SWCNTs on one side of bulky paper were well developed in a speparation from the filter paper, which were formed by being sucked through the filter pores during the pressurized filtration. The bucky paper showed a very high peak current density of field emission up to $200\;mA/cm^2$ and uniform field emission images on phosphor, which seems very promising to be applied to vacuum microelectronics such as microwave power amplifiers and x-ray sources.

• Journal of Korean Physical Therapy Science
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• v.19 no.3
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• pp.17-22
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• 2012

Background : The purpose of this study was to investigate the relationship between an agility and a concentration, an auditory reaction time and a muscle power. Methods : Twenty one healthy female college students who were 20-21 years participated in the experiment; after being introduced to the methods, they voluntarily signed a consent form. And they received several test related with this study; side step test for an agility, Harris & Harris test for a concentration, brain auditory evoked potential test for an auditory reaction time and vertical jump test for a muscle power. Result : There was no relationship between the agility and the concentration and the auditory reaction time. However, the muscle power related with the agility significantly. Conclusion : In conclusion, these findings suggest that a muscle power training is a good way to promote an agility. So, we can find out that, in an player who requires an agility, a muscle power training is the most important way for promoting an agility than a concentration training or an auditory reaction time training.

• Archives of Plastic Surgery
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• v.37 no.4
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• pp.499-530
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• 2010

Purpose: Lateral osteotomy is an essential step in the correction of nasal bony asymmetry. Direct visualization allows accurate repositioning of the nasal bones compared to blind techniques, which require precision and manual dexterity. We propose direct visualization procedures in open corrective rhinoplasty. Methods: The technique was used on 16 patients. All patients underwent open rhinoplasty with a columellar incision. The marginal incisions were extended on either side to allow access to the piriform aperture. A double hook was used to caudally retract the lower lateral cartilages and the fibrous connections between the upper and lower lateral cartilages were released until the piriform aperture was visualized. Through the incision, lateral osteotomy was performed using a reciprocating saw at that time with direct visualization. Additional procedures including augmentation rhinoplasty, hump resection, septoplasty and tip plasty were performed simultaneously. Results: This method provided excellent exposure to the lateral nasal bones and allowed the lateral osteotomy to be carried out precisely using the reciprocating saw. Conclusion: This extended open rhinoplasty method is suitable for most individuals, allowing a wide surgical field.

• Journal of Biomedical Engineering Research
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• v.14 no.2
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• pp.155-162
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• 1993

The human's biomechanical structure keeps an optimal state by adapting the original biomechanical structure according to a change in the physical environment. This phenomenon is believed to be the main cause of loosening of the total hip replacement which is used widely in these days. In this study the bone density change due to artificial hip joint, which is generally believed as bone-remodeling, was investigated by the finite element method. For this, 2-D FEM models with 4 nodal point elements were constructed for intact and implanted cases. The density was calculated by comparing the relative amounts of effective stress for these two cases. In this way, calculated new density values were used in the next step as input values and this procedure repeated until convergence was obtained. Severe density change was detected at the femoral cortex of the proximal-medial side as expected. Moreover, following surprising result was found from this analysis. Titanium alloy prosthesis showed less density change compared to stainless steel prosthesis at earlier stage, however, almost same amount of the density change was detected at final stage. It was also found that other design parameters could not significantly affect its density change.

• Journal of Dental Anesthesia and Pain Medicine
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• v.17 no.4
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• pp.313-316
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• 2017

Mask ventilation, the first step in airway management, is a rescue technique when endotracheal intubation fails. Therefore, ordinary airway management for the induction of general anesthesia cannot be conducted in the situation of difficult mask ventilation (DMV). Here, we report a case of awake intubation in a patient with a huge orocutaneous fistula. A 58-year-old woman was scheduled to undergo a wide excision, reconstruction with a reconstruction plate, and supraomohyoid neck dissection on the left side and an anterolateral thigh flap due to a huge orocutaneous fistula that occurred after a previous mandibulectomy and flap surgery. During induction, DMV was predicted, and we planned an awake intubation. The patient was sedated with dexmedetomidine and remifentanil. She was intubated with a nasotracheal tube using a video laryngoscope, and spontaneous ventilation was maintained. This case demonstrates that awake intubation using a video laryngoscope can be as good as a fiberoptic scope.

• Journal of Menopausal Medicine
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• v.24 no.3
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• pp.143-149
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• 2018

Lack of adequate sleep has become increasingly common in our 24/7 modern society. Reduced sleep has significant health consequences including metabolic and cardiovascular disorders, and mental problems including depression. In addition, although the increase in life expectancy has provided a dream of longevity to humans, the occurrence of osteoporosis is a big obstacle to this dream for both male and female. It is known that insomnia and bone health problems, which are very critical conditions in human life, interestingly, share a lot of pathogenesis in recent decades. Nevertheless, due to another side effects of the synthetic drugs being taken for the treatment of insomnia and osteoporosis, patients have substantial anxiety for the safety of drugs with therapeutic expectation. This review examines the pathogenesis shared by sleep and osteoporosis together and herbal medicine, which has recently been shown to be safe and efficacious in the treatment of both diseases other than synthetic drugs. We suggestions for how to treat osteoporosis. These efforts will be the first step toward enabling patients to have comfortable and safe prescriptions through a wide selection of therapeutic agents in the future.

• Earthquakes and Structures
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• v.2 no.4
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• pp.337-356
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• 2011

In this paper, cable-stayed bridges with single pylon and two equal side spans, with variations in geometry and span ranging from 120 m to 240 m have been studied. 3D models of the bridges considered in this study have been analysed using ANSYS. As the first step towards a detailed seismic analysis, free vibration response of different geometries is studied for their mode shapes and frequencies. Typical pattern of free vibration responses in different frequencies with change in geometry is observed. Further, three different seismic loading histories are chosen with various characteristics to find the structural response of different geometries under seismic loading. Effect of variation in pylon shape, cable arrangement with variation in span is found to have typical characteristics with different structural response under seismic loading. From the study, it is observed that the structural response is very much dependent on the geometry of the cable-stayed bridge and the characteristics of the seismic loading as well. Further, structural responses obtained from the study would help the design engineers to take decisions on geometric shapes of the bridges to be constructed in seismic prone zones.