• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.3
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• pp.1-8
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• 1972

The characteristics of tunnel diode pair circuit biased within the negative resistance region has also the voltage-control type negative resistance region, and the voltage at the center point of negative resistance region is described as the square-wave relaxation oscillation. In this paper, the period T, positive duration T1, negative duration T2 of the pulse are obatined from the characteristic curve T, positive duration T1, negative duration T2 of the pulse are obtained from the characteristic curve and observed actually, considring the fact that the pulse width and the period of square-wave at the center point of the negative resistance region is able to be controlle dby the blas volgate. Mereover, the relationship between T, T1 or T2 and circuit parameters is searched for and the Circuit parameters that satisfy the conditions of T1-T2 being proportional to the variation of bias voltage with Teonstant are determined. Thereafter, the bias voltage and the signal voltage are inserted serially to the PWM circuit and the characteristics of that circuit is analyzed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.633-643
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• 2003

UWB impulse radio signals have an very short duration, extremely wide bandwidth and share the same frequency spectrum with other existing systems. It was determined by the Federal Communications Commission (FCC) that UWB systems could cause interference with other systems, such as Global Positioning System (GPS) for example. Therefore, at present. the FCC has restricted the use of UWB systems to frequencies above 3.1㎓. In this paper, We evaluated performance of UWB system using proposed pulses in ［1］［2］ that are strictly limited in time to remove interference while, at the same time, contain their power distribution to a frequency band from 3.1㎓ to 10.6㎓. In particular, We evaluated the BER Performance in relation to system parameters such as pulse duration. $\delta$, the number of users. Nu. and the number of symbols, M. We found the optimal pulse duration $\delta$ through computer simulation using developed UWB pulses in ［1］［2］. It is shown that performance evaluation between the UWB communication system using these UWB pulses ［1］［2］and the Gaussian monocycle pulse in M-ary PPM and BPSK schemes. These results can be contributed to construct M-ary PPM UWB communication system in terms of multiuser parameters and pulse duration.

• Child Health Nursing Research
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• v.5 no.1
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• pp.48-58
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• 1999

The purpose of this study was to determine the most accurate technique measuring the apical pulse rate, using three counting duration 15, 30 and 60 seconds, and two methods start ‘0’ and start ‘1’. The instrument used in the study was the EKG monitor, stethoscope and stopwatch. Data was analyzed by utilizing SPSSWIN program. General characteristics of the subjects were analyzed by frequency, percentile, mean, SD. The subject of this research is made up of 46 children and 20 nurses. The children were infants, & under the age of 5. They were hospitalised in PICU & NICU in 2 tertiary hospitals in seoul from Jan. 1. 1998 to Sep. 10. 1998. The measurement of starting 1 & measurement of starting ‘0’ used the T-test to find out the measurement error. Apical pulse duration of 15, 30, 60 seconds were used to find out measurement error, the measurement error depend on experience of Nurse were analyzed by using ANOVA. The result of this study are as follows. 1. When comparing the starting poin of apical pulse 0&1, starting with 1 the measurement error is less, but not statiscally significant. 2. When counting the apical pulse by 15, 30,60 sec. ; 60 seconds counting duration was more accurate, but not statistically significant. 3. The mean of measure error ; Group under 100/min, is 10.33 ; from 100 re 119/min, is 8.30 ; from 120 to 139/min, is 4.76 ; from 140 to 159/min, is 6.09 ; above 160, is 17.83. The differences of these groups are statistically significant. When 60sec were counted, under 140/min the mean of measurement error is 3.4. Also when 30 seconds were counted from 140/min to 159/min the measurement error is 7.14, above 160/min the measurement error is 16.4. That measurement mean is the smallest than the other durations. During the 15 sec. count the measurement error was the largest of them all. 4. By the experience of the nurses, the apical pulse count measurement error was discovered. Under a year experience this measurement error was the largest(11.09), 1 year to under 3 years, the error is the smallest(4.86). 3 year to under 6 years the error is 8.33, 5 years above the error is 6.11 but this is not statistical significant. Under a year experience when counting 15, 30, 60 seconds the error is the largest. The group of the nurses from a year to under 3 years, the measurement error is the smallest of all the groups. The result of the study is to determine the technique measuring the apical pulse rate, Hargest (1974), starting point ‘0’ is not proved. When the pulse rate increases the 30 sec measurement rate is accurate. Under 140/min the 60 sec measurement rate is the most accurate. Depending on the nurses experiences, there is a variable difference to the apical pulse rate measurement. Especially new nurses training courses should enforce the children’s pulse rate count and the basic vital signs.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1427-1435
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• 2002

The main aim of the present article is numerically to investigate the micro-scale heat transfer phenomena in a silicon microstructure irradiated by picosecond-to-femtosecond ultra-short laser pulses. Carrier-lattice non-equilibrium phenomena are simulated with a self-consistent numerical model based on Boltzmann transport theory to obtain the spatial and temporal evolutions of the lattice temperature, the carrier number density and its temperature. Especially, an equilibration time, after which carrier and lattice are in equilibrium, is newly introduced to quantify the time duration of non-equilibrium state. Significant increase in carrier temperature is observed for a few picosecond pulse laser, while the lattice temperature rise is relatively small with decreasing laser pulse width. It is also found that the laser fluence significantly affects the N 3 decaying rate of Auger recombination, the carrier temperature exhibits two peaks as a function of time due to Auger heating as well as direct laser heating of the carriers, and finally both laser fluence and pulse width play an important role in controlling the duration time of non-equilibrium between carrier and lattice.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1300-1305
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• 2012

A triaxial Blumlein pulse forming line has been designed to generate a pulse whose voltage is ~300 kV, pulse duration is ~5 ns, and rise time is ~500 ps. It turns out, however, that the rise time of the pulse becomes much longer than 500 ps due to parasitic inductances and capacitances existing inside the system. A peaking switch has been developed to shorten the rise time of the pulse from Blumlein pulse forming line. In the peaking switch, a wedge-shaped dielectric material (MC 901 nylon) is employed to surround the electrode on the antenna side. This shape inhibits an abrupt change of the output impedance, thereby minimizing the reflection of the output pulse. Experimental results show that the peaking switch is capable of improving the rise time of the pulse at a level of 500 ps.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.2
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• pp.167-175
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• 2015

A retinal prosthesis is being developed for the restoration of vision in patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Determining optimal electrical stimulation parameters for the prosthesis is one of the most important elements for the development of a viable retinal prosthesis. Here, we investigated the effects of different charge-balanced biphasic pulses with regard to their effectiveness in evoking retinal ganglion cell (RGC) responses. Retinal degeneration (rd1) mice were used (n=17). From the ex-vivo retinal preparation, retinal patches were placed ganglion cell layer down onto an $8{\times}8$ multielectrode array (MEA) and RGC responses were recorded while applying electrical stimuli. For asymmetric pulses, 1st phase of the pulse is the same with symmetric pulse but the amplitude of 2nd phase of the pulse is less than $10{\mu}A$ and charge balanced condition is satisfied by lengthening the duration of the pulse. For intensities (or duration) modulation, duration (or amplitude) of the pulse was fixed to $500{\mu}s$($30{\mu}A$), changing the intensities (or duration) from 2 to $60{\mu}A$(60 to $1000{\mu}s$). RGCs were classified as response-positive when PSTH showed multiple (3~4) peaks within 400 ms post stimulus and the number of spikes was at least 30% more than that for the immediate pre-stimulus 400 ms period. RGC responses were well modulated both with anodic and cathodic phase-1st biphasic pulses. Cathodic phase-1st pulses produced significantly better modulation of RGC activity than anodic phase-1st pulses regardless of symmetry of the pulse.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.1
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• pp.52-63
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• 1998

The impact programmer for impact test was designed and the impact analysis was conducted. The effects of the material and geometric parameters on the impact force and pulse shape were investigated. The impact characteristics were examined by experimental and finite element method. The impact test was conducted with free drop impact tester. The ABAQUS/Explicit 5.5 version was used for finite element analysis. The geometric parameters of the conical and dome type impact programmer were analyzed. The polyurethane impact programmers were fabricated and tested. The effects of the hardness and thickness of the impact programmer were studied. The peak acceleration and time duration of impact programmer have close correlation with the hardness, impact energy and thickness of the impactor. The experiment was good agreement with analytical predictions. The impact pulse shape generated with polyurethane impact programmer was half sine shape. The maximum impact force was proportional to impact energy. The impact acceleration was decreased with thickness of impact programmer. The maximum impact time duration level was about 2 msec.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.3
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• pp.177-185
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• 2000

In this study, the characteristics of various electricity and high resistivity ash collection were measured at superimposed nanosecond pulse energization. The pulse was generated through the hydrogen thyratron. Superimposed pulse was nanosecond duration pulse that had fast pulse rising time 100[ns], short pulse width 500∼850[ns] and pulse fall time 400∼750[ns]. The results of this study are summarized as followings; Frist, compared with the DC ESP(electrostatic precipitator), superimposed pulse ESP could induce higher peak voltage, and had the about 30[%] reduction of ESP collection area and 50∼80[%] reduction of power consumption. showing the same efficiency. Second, enhancement factor H had 1.9∼3.6 with the increase of migration velocity.

• Journal of Information Processing Systems
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• v.18 no.1
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• pp.89-96
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• 2022

A novel multistage pulse jamming suppression algorithm was proposed to solve the anti-pulse jamming problem encountered in navigation receivers. Based on the characteristics of the short duration of pulse jamming and distribution characteristics of satellite signals, the pulse jamming detection threshold was derived. From the experiments, it was found that the randomness of pulse jamming affects jamming suppression. On this basis, the principle of the multistage anti-pulse jamming algorithm was established. The effectiveness of the anti-jamming algorithm was verified through experiments. The characteristics of the algorithm include simple determination of jamming detection threshold, easy programming, and complete suppression of pulse jamming.

• 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.