• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1139-1146
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• 2007

Cultures of Saccharomyces cerevisiae were subjected to the effect of PEF (pulse electric field) and a source of selenium. The culture period after which yeast cells were subjected to PEF treatment was optimized, as was the duration of the exposure. Optimization of the nutrient medium composition in S. cerevisiae cultures resulted in an over 1.8-fold increase in selenium accumulation with relation to cultures on the initial substrate. Optimization of the pH value and of culture duration resulted in selenium accumulation increase by approximately 78%. A significant correlation was found between the accumulation of selenium in yeast cells and its concentration in the culture substrate. The highest accumulation of selenium in the biomass of yeast, approx. $240\;{\mu}g/g$ d.m., was obtained after 15-min exposure to PEF on a 20-h culture. An approx. 50% higher content of selenium in cells was recorded, as compared with the control culture without the application of PEF.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.628-634
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• 2005

We have simulated and proposed novel optical cavity, which has two elliptical mirrors, for NDIR gas sensor module and have tested it from 0 ppm to 2,000 ppm $CO_2$ concentration. The proposed sensor module shows the maximum peak voltage at 500 ms pulse modulation time, however, it shows a maximum voltage changes at 200 ms pulse duration with 18,000 times amplification gain. From 0 ppm to 2,000 ppm, the voltage difference of sensor module $({\Delta}V)$ shows 360 mV at 200 ms pulse duration and 3 sec turn-off time. The response time of designed sensor module is about 30 seconds.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.251-256
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• 2011

The radial overcut in micro electrochemical machining was investigated. The prediction of overcut is important not only for the machining accuracy but also for the shape control of micro structures. In micro ECM, machining gap or overcut depends on electrolyte, pulse voltage, pulse duration and dissolution time etc. Understanding of electrochemical dissolution rate is necessary for the overcut prediction. In this paper, the radial overcut of micro electrochemical machining according to pulse duration and dissolution time was simulated using electrochemical principles and also experimentally estimated.

• The Journal of the Acoustical Society of Korea
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• v.28 no.3E
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• pp.88-92
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• 2009

The target strength (TS) is calculated from the measured signal using the definition of the peak TS (PTS) or the integrated TS (ITS). These two types of TS sometimes give different results depending on what the pulse duration is. In this paper, we model the scattered time signal by the numerical code based on the physical diffraction theory and examine the effect of the pulse duration on the value of PTS or ITS. The transformed TS (TTS) for the frequency domain is used as a reference solution.

• Structural Engineering and Mechanics
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• v.73 no.2
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• pp.181-190
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• 2020

In this paper, non-linear dynamic buckling behaviour of laminated composite curved panels subjected to dynamic in-plane axial compressive loads is studied using finite element methods. The work is carried out using the finite element software ABAQUS. The curved panels are modelled with S4R element and the nonlinear dynamic equilibrium equations are solved using the ABAQUS/Explicit algorithm. The effect of aspect ratio, radius of curvature and thickness are studied. The importance of orientation of plies in the direction of loading is also reiterated in this study. Vol'mir's criterion is used to calculate the dynamic buckling loads. The panels are subjected to rectangular pulse load of various amplitude and durations and the responses are observed. For particular loading amplitude, a critical value of loading duration is observed beyond which the variation of dynamic buckling load is insignificant. It is also observed that, the value of dynamic bucking load reduces as the loading duration is increased though the reduction is not much after a particular loading duration.

• Journal of Environmental Science International
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• v.19 no.1
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• pp.61-68
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• 2010

In this study, we analyzed the pulse-duration, pulse-interval and peak-frequency of echolocation call in three species as Rhinolophus ferrumequinum, Pipistrellus abramus, and Myotis macrodactylus. The peak frequency and pulse duration for above mentioned species were 69 kHz, 47 kHz and 49 kHz and $69.39{\pm}8.76\;ms$, $4.95{\pm}0.77\;ms$ and $3.09{\pm}0.48\;ms$ for R. ferrumequinum, P. abramus and M. macrodactylus, respectively. The pulse intervals for R. ferrumequinum, P. abramus and M. macrodactylus were $103.61{\pm}9.05\;ms$, $67.59{\pm}3.47\;ms$ and $66.35{\pm}4.96\;ms$, respectively. The pulse pattern of R. ferrumequinum was setting into a short FM call and linked to long CF call and went through the short FM call again. The pulse pattern of M. macrodactylus was comprised with serial short FM call and the CF call was not checked up in accordance with the spectrogram analysis. The long FM call and short CF call got join together for the P. abramus and the peak frequency was checked up at the pulse ending as CF call.

• Journal of Magnetics
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• v.15 no.4
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• pp.213-220
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• 2010

Since the hypothalamus immediately reacts to a nerve by processing all the information from the human body and the external stimulus being conducted, it performs a significant role in internal secretion; thus, a diverse and rapid stimulus pulse is required. By detecting Zero Detector accurately via the application of AVR on-Chip (ATMEL) using commercial electricity, chopping generates a stimulus pulse to the brain using an IGBT gate to designate a new magnetic stimulation following treatment and diagnosis. To simplify and generate a diverse range of stimuli for the brain, chopping can be used as a free magnetic stimulator. Then, commercial frequency (60Hz) is chopped precisely at the first level of the leakage transformer to deliver an appropriate stimulus pulse towards the hypothalamus when necessary. Discharge becomes stable, and the chopping frequency and duty-ratio provide variety after authorizing a high-pressure chopping voltage at the second level of the magnetic stimulator. These methods have several aims. The first is to apply a variable stimulus pulse via accurate switching frequency control by a voltaic pulse or a pulse repetition rate, according to the diagnostic purpose for a given hypothalamus. Consequently, the efficiency tends to increase. This experiment was conducted at a maximum of 210 W, a magnetic induced amplitude of 0.1~2.5 Tesla, a pulse duration of $200{\sim}350\;{\mu}s$, magnetic inducement of 5 Hz, stimulus frequency of 0.1~60 Hz, and a duration of stimulus train of 1~10 sec.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1773-1775
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• 1998

This paper deals with the pulse generator using PFN(Pulse Forming Network), and its operation characteristics and application. Two kinds of pulse generator were composed of the best appropriate condition circuit. The output current of the one pulse generator has the rise time of 28 ns and the pulse duration of $7{\mu}s$. The other pulse generator has high current of about 2kA. By use of the former generator with rapid rise time, the impulse impedance characteristic of ground electrodes was investigated with measuring the ground potential rise when the pulse current was injected into the ground electrode.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.127-132
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• 2001

We describe the pulse forming of pulsed $CO_2$laser using multi-pulse superposition technique. A various pulse length, high duty cycle pulse forming network(PFN) is constructed by time sequence. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on SCRs of three PFN modules consecutively at a desirable delay time with the aid of PIC one-chip microprocessor. The power supply for this experiment consists of three PFN modules. Each PFN module uses a capacitor, a pulse forming inductor, a SCR, a High voltage pulse transformer, and a bridge rectifier on each transformer secondary. The PFN modules operate at low voltage and drive the primary of HV pulse transformer. The secondary of the transformer has a full-wave rectifier, which passes the pulse energy to the load in a continuous sequence. We investigated laser pulse shape and duration as various trigger time intervals of SCRs among three PFN modules. As a result, we can obtain laser beam with various pulse shapes and durations from about 250 $mutextrm{s}$ to 600 $mutextrm{s}$.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.44-44
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• 2003

Free electron lasers (FEL) have, at least, the following advantages in comparison to conventional lasers： FEL can be designed for any arbitrary given emission wavelength. It is continuously tunable within wide band. Easy to get single-mode emission. Easily controlled emission structure (pulse duration, repetition rate, and pulse energy). (omitted)