• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.45-48
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• 1997

The low frequency pulsed MIG welding process of new current waveform control to switch over unit pulse conditions (pulse current, pulse duration) in the fixed cycle was developed and its effect were investigated for aluminium and its alloy. By using this new welding process, the bead appearance having clear ripple pattern, such as TIG welding bead can be obtained and the gap tolerance of lap and butt welding joint can be expanded.

• Laser Solutions
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• v.8 no.2
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• pp.7-12
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• 2005

The material processing of UV nanosecond pulse laser cannot be avoided the material shape change and contamination caused by interaction of base material and laser beam. Nowadays, ultra short pulse laser shorter than nanosecond pulse duration is used to overcome this problem. The advantages of this laser are no heat transfer, no splashing material, no left material to the adjacent material. Because of these characteristics, it is so suitable for micro material processing. The processing of sapphire wafer was done by UV 355nm, green 532nm, IR 1064nm. X-Y motorized stage is installed to investigate the proper laser beam irradiation speed and cycles. Also, laser beam fluence and peak power are calculated.

• Journal of Dental Anesthesia and Pain Medicine
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• v.15 no.4
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• pp.201-205
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• 2015

Background: This prospective, randomized, double-blind, clinical study was conducted to compare the effects of 4% articaine with 1:100,000 epinephrine (A100) and 4% articaine with 1:200,000 epinephrine (A200) on the vital signs and onset and duration of anesthesia in an inferior alveolar nerve block (IANB). Methods: In the first appointment, an IANB was performed by injecting A100 or A200 in 1 side of the mouth (right or left) randomly in patients referred for extraction of both their first mandibular molars. In the second appointment, the protocol was repeated and the other anesthetic solution was injected in the side that had not received the block in the previous session. Systolic and diastolic blood pressures (SBP and DBP) and pulse rate were measured during and 5 min after the injection. The onset and duration of anesthesia were also evaluated. Data were analyzed using t-test and Mann-Whitney U-test, and p-value was set at 0.05. Results: SBP and pulse rate changes were slightly more with A100; however, DBP changes were more with A200, although the differences were not significant (P > 0.05). There were no statistically significant differences in the parameters evaluated in this study. The onset and duration of anesthesia, and the changes in SBP, DBP, and pulse rate during and 5 min after the injection were the same in both the groups. Conclusions: For an IANB, A200 and A100 were equally efficient and successful in producing the block. Epinephrine concentration did not influence the effects of 4% articaine.

• Journal of Biomedical Engineering Research
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• v.30 no.4
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• pp.347-354
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• 2009

For the reliable transmission of meaningful visual information using prosthetic electrical stimulation, it is required to develop an effective stimulation strategy for the generation of electrical pulse trains based on input visual information. The characteristics of neuronal activities of retinal ganglion cells (RGCs) evoked by electrical stimulation should be understood for this purpose. In this study, for the development of an optimal stimulation strategy for visual prosthesis, we analyzed the neuronal responses of RGCs in rd1 mouse, photoreceptor-degenerated retina of animal model of retinal diseases (retinitis pigmentosa). Based on the in-vitro model of epiretinal prosthesis which consists of planar multielectrode array (MEA) and retinal patch, we recorded and analyzed multiunit RGC activities evoked by amplitude-modulated electrical pulse trains. Two modes of responses were observed. Short-latency responses occurring at 3 ms after the stimulation were estimated to be from direct stimulation of RGCs. Long-latency responses were also observed mainly at 2 - 100 ms after stimulation and showed rhythmic firing with same frequency as the oscillatory background field potential. The long-latency responses could be modulated by pulse amplitude and duration. From the results, we expect that optimal stimulation conditions such as pulse amplitude and pulse duration can be determined for the successful transmission of visual information by electrical stimulation.

• Journal of International Academy of Physical Therapy Research
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• v.5 no.2
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• pp.752-756
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• 2014

This study investigated the effects of changes to the pulsation factor of pulsed direct currents on wound healing. Patients with a pressure ulcer at a care hospital for the elderly were randomly divided into three groups: Group 1 involved the application of $100{\mu}s$ in pulse duration, 10 ms in pulse period, 100 pps in a pulsation factor, 15 mA in pulse amplitude, and polarity red+ by using pulsed direct currents; Group 2 involved a change of pulse period to 8 ms; and Group 3 received general wound management. Although there were no statistically significant differences in the changing stages of pressure ulcers among the groups, all the groups dropped in numerical stages. In the two groups to which pulsed direct currents were applied, there was a statistically significant reduction in the stages of pressure ulcers from the initial assessment to the 12-week assessment (p<.05). Even though there were no statistically significant differences in changes to the area of pressure ulcers among the groups, a statistically significant decrease was found in pulsed direct current group 2 whose pulse period was shortened (p<.05). There was no difference in the healing rate of pressure ulcers among the groups, but it made a numerical increase in pulsed direct current group 1 and group 2 and a numerical decrease in group 3. There were no significant differences in the characteristics of those who had a full recovery among the groups. Those findings indicate that pulsed direct currents have positive effects on the wound healing of patients with a pressure ulcer and that a treatment with pulsed direct currents whose pulsation factor is raised by reducing the pulse duration is especially effective.

• Current Optics and Photonics
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• v.1 no.3
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• pp.203-206
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• 2017

We report a passive Q-switching of an all-fiber erbium-doped fiber laser delivering high pulse energy by using a high quality single-walled carbon nanotube saturable absorber (SWCNT-SA). A side-polished fiber coated with the SWCNT is employed as an in-line SA for evanescent wave interaction between the incident light and the SWCNT. This lateral interaction scheme enables a stable Q-switched fiber laser that generates high pulse energy. The central wavelength of the Q-switched pulse laser was measured as 1560 nm. A repetition rate frequency of the Q-switched laser is controlled from 78 kHz to 190 kHz by adjusting the applied pump power from 124 mW to 790 mW. The variation of pulse energy from 51 nJ to 270 nJ is also observed as increasing the pump power. The pulse energy of 270 nJ achieved at maximum pump power is 3 times larger than those reported in Q-switched all-fiber lasers using a SWCNT-SA. The tunable behaviors in pulse duration, pulse repetition rate, and pulse energy as a function of pump power are reported, and are well matched with theoretical expectation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.7
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• pp.52-58
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• 2013

The two-dimensional finite difference time domain algorithm is used to numerically reconstruct the electron density profile in O-mode ultrashort pulse reflectometry. A Gaussian pulse is employed as the source of a probing electromagnetic wave. The Gaussian pulse duration is chosen in such a manner as to have its frequency spectrum cover the whole range of the plasma frequency. By using a number of numerical band-pass filters, it is possible to compute the time delays of the frequency components of the reflected signal from the plasma. The electron density profile is reconstructed by substituting the time delays into the Abel integral equation. As a result of simulation, the reconstructed electron density profile agrees well with the assumed profile.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.471-474
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• 1997

Several selective excitation pulses are used in MRI. Because of the nonlinearity of the Block equation, the pulse problem is nonlinear generally. Recently, Shinnar & Le Roux have proposed a direct solution of this problem. In this paper, we introduce the SLR algorithm and design pulses using SLR algorithm. This SLR pulse produces a specified slice profile. For example, we demonstrate the sinc function pulse with piece wise constant duration ${\Delta}t$. Further, we will design $\pi/2$ pulse and slice profile.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.128.2-128
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• 2001

Since pulse energization can improve the performance of Electrostatic Precipitator(ESP) for high resistivity dusts, high voltage micro-pulse generators, 70kV 140usec duration pulses for instance, are commonly developed by LC resonance for most pulse powered ESPs. Consisting of discharge electrodes and collecting electrodes, ESP has its own capacitance like a capacitor. ESP's capacitance affects the LC resonance phenomenon with resonance inductor and capacitor of micro-pulse power supply, engineers should acquire the value of their ESP to design for proper power supply design. In this study, we describe the ESP's capacitance measuring device which has the same topology with our new developed micro-pulse power supply. In this microcontroller based capacitance measuring equipment, ESP's capacitance can be calculated easily through ...

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.7-13
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• 2010

We report a hybrid DPSSL with a pulse parameter variable LD seed, all-fiberized polarization-maintained pulsed Yb-doped fiber preamplifier chains, and a bulk Nd:$YVO_4$ power amplifier. Pulse parameter of LD seed was controlled by direct current modulation. The hybrid DPSSL generates 1064 nm laser pulses with an average power of 40W, a pulse duration of 20-40ns, and a repetition rate of 100-500kHz.