• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.1
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• pp.55-60
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• 2017

Capacitor Charging Power Supply(CCPS) is one of the most important components of a pulsed power system. The CCPS is widely used in source of lasers, accelerators and plasma generators. This paper presents design of a dead time control circuit and operation characteristics for stable high repetition rate of high voltage CCPS. The CCPS consists of battery, high voltage transformer and controller with a dead time control circuit. A dead time control circuit was simulated by PSpice. The performance test of the CCPS was carried out with a 7[nF] load capacitor at output voltage of 50[kV] and a pulse repetition frequency of 100[Hz]. As a result, we can verify that charging and discharging waveform is stable at 100[Hz]. The experiment results indicate that 3[ms] dead time made it possible for stable high repetition rate of 100[Hz]. This paper paves the way for designing an advanced CCPS which is more applicable outside experiments.

• Textile Coloration and Finishing
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• v.16 no.3
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• pp.1-7
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• 2004

To study the dyeability(K/S value) and surface color of silk fabrics dyed with Impatiens balsamina extract, its flower, leaf and stem, was extracted by water. This paper investigated some experiments with Impatiens balsamina extract under the various dyeing conditions such as dyeing temperature, dyeing time, repetition of dyeing, dyeing pH with silk fabrics. The results obtained were as follows. 1. It was found that it $\lambdamax$. of silk fabrics dyed with Impatiens balsamina extract was 260nm and its flower, leaf, stem and flowers(white, pink, violet) had same it $\lambdamax$ at 260nm. 2. K/S value was increased when dyeing temperature, repetition of dyeing and time was higher, value of munsell of silk fabrics dyed with Impatiens balsamina extract was yellow-red. dyeing temperature, repetition of dyeing and time was higher, shifted to longer wavelength side. 3. pH added acetic acid was colored reddish yellow-red, but pH added alum was colored yellowish yellow-red in silk fabrics dyed with Impatiens balsamina extract and repetition of dyeing was increased the dye-uptake.

• ETRI Journal
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• v.21 no.4
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• pp.29-40
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• 1999

In this paper, we show the robustness of a proposed system using both a frequency diversity and a time diversity effect when the channel assumptions are relaxed such that all sub-bands are not independent fading. We take time-repetition coding with interleaving such that the repetition code symbols are spaced sufficiently far apart to guarantee time diversity. We also incorporate offset multicarriers into a proposed multicarrier DS-CDMA system in a different way compared to that of [10] to reduce the total multiple access interference. When we take a convolutional encoder instead of a time-repetition encoder, and again use both time diversity and frequency offset, then we can obtain the significant performance gain.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.3
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• pp.167-171
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• 2014

This paper examines the destruction behavior of NPN BJT (bipolar junction transistor) by repetition pulse. The injected pulse has a rise time of 1 ns and the maximum peak voltage of 2 kV. Pulse was injected into the base of transistor. Transistor was destroyed, current flows even when the base power is turned off. Cause the destruction of the transistor is damaged by heat. Breakdown voltage of the transistor is 975 V at single pulse, and repetition pulse is 525~575 V. Pulse repetition rate increases, the DT (destruction threshold) is reduced. Pulse Repetition rate is high, level of transistor destruction is more serious.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.sup3
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• pp.135-141
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• 2016

Since the mean age of breast cancer in women living in developing countries, compared with those in developed countries, is lower by about 10 years, repetition of mammography can play an important role in reducing morbidity and mortality. Hence, this study aimed to investigate the relationship between family history of breast cancer and risk perception and its impact on repetition of mammography. In this cross-sectional study, 1,507 women aged 50 years and older, referred to the mammography center of Regions 1 and 6 in Tehran, Iran, were enrolled. Data were collected using a self-report questionnaire and analyzed using SPSS and LISREL. According to our findings, knowledge about the time interval of mammography was found to have the highest correlation with repetition of mammography (r=0.4). Among the demographic variables, marital status (${\beta}$= -0.1) and family history of breast cancer (${\beta}$=0.1) had the most direct and significant impact on repetition of mammography (P <0.05). Among the other variables studied, knowledge (${\beta}$=-0.5) had the highest direct and significant impact on repetition of mammography (P <0.05). Family history of breast cancer was one of the predictors of repetition of mammography, but the results did not prove any relationship with risk perception. Further studies are needed to assess the effect of risk perception and knowledge about time interval on the initiation and continuation of mammography.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.1
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• pp.101-106
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• 2014

PURPOSE: This study was to provide reference data and examine stroke and healty older differences in sit-to-stand test. This study were to determine utility of the 5 repetition sit to stand for discriminating between fallers and non-fallers, identifying an appropriate cutoff score to delineate between the groups. METHODS: Ninety-five participants were recruited. Seventy-two individuals with stroke and twenty-three healthy older agreed to participate in the study. Falls were recorded using a self-administered questionnaire. The 5 repetition sit to stand test measured the time taken to complete t repetitions of the sit to stand maneuver. The time from the initial seated position to the final seated position after completing five stands was the test measure. A cutoff score regarding 5 repetition sit to stand performance in fallers vs. non-fallers, stroke patients vs. healthy older and <60 vs. $$\geq_-$$ age groups was determined using and ROC curve. RESULTS: Cutoff score of 9.9 seconds were found to be discriminatory between healthy older and subjects with stroke. Cutoff score of 15.5 seconds were found to be discriminatory between fallers and non-fallers. Cutoff score of 18.3 seconds were found to be discriminatory between <60 and $$\geq_-$$ age groups. CONCLUSION: The 5-repetition sit-to stand test is quick, easily administered measure useful for gross determination of fall risk in people with stroke.

• Journal of Engineering Education Research
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• v.16 no.4
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• pp.30-36
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• 2013

Applying intuitive learning method on engineering education, especially for the mechanical engineering, is hardly found from the previous case studies and is not easily proved its beneficial verification. Verbal repetition is also rarely used to investigate its positive effects on educational methodology for both science and engineering disciplines. To prove the education effects of these two methods; we used intuitive thinking time period at the beginning of each lecture and let students repeat the concepts and the equations verbally. These two methods were related to the subjects of each lecture, and were used for students to try to draw engineering thinking from natural phenomena that they could easily experience in daily life. The methods could help them to memorize theoretical ideas. We investigated the effects of intuition and verbal repetition methods by comparing the scores of final exam with those of midterm exam. The results revealed significant improvement; 77.6% of the students achieved higher score in their final exam compared to midterm exam. We plan to investigate qualitative contributions of intuition and verbal repetition methods to the students' achievement for the further research.

• Textile Coloration and Finishing
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• v.15 no.1
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• pp.1-7
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• 2003

To study the dyeability(ΔE value) and color depth of silk fabrics dyed with Impatiens balsamina extracts. its flower, leaf and stem was extracted by water. This paper investigated some experiments under the various dyeing conditions such as dyeing temperature, dyeing time, repetition of dyeing, dyeing pH with silk fabrics dyed with Impatiens balsamina extracts. The results obtained were as follows 1. It was found that $\lambda_{max}$ of silk fabrics dyed with Impatiens balsamina extract was 260nm and its flower, leaf , stem and different colored flower(white, pint violet) had same $\lambda_{max}$ at 260nm. 2. $\Delta{E}$ values were increased when dyeing temperature, repetition of dyeing and time was higher, value of munsell of silk fabrics dyed with Impatiens balsamina extract was Yellow-Red. But dyeing temperature, repetition of dyeing and time was higher, shifted to longer wavelenth side. 3. Silk fabric dyed with Impatiens balsamina extracts at acidic pH was colored reddish Yellow-Red, alkali bath colored yellowish Yellow-Red in silk fabrics dyed with Impatiens balsamina extract.

• Journal of the Optical Society of Korea
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• v.17 no.5
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• pp.357-361
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• 2013

A regenerative Er-doped fiber amplifier system for a high-repetition-rate optical pulse train is investigated for the first time. A signal pulse train with a wavelength tuning range of 18 nm is produced by a passive mode-locked fiber laser based on a nonlinear polarization rotation technique. In order to realize the amplification, an optical delay-line is used to achieve time match between the pulses' interval and the period of pulse running through the regenerative amplifier. The 16 dB gain is obtained for an input pulse train with a launching power of -30.4 dBm, a center wavelength of 1563.4 nm and a repetition rate of 15.3 MHz. The output properties of signal pulses with different center wavelengths are also discussed. The pulse amplification is found to be different from the regenerative amplification system for CW signals.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.330-333
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• 2000

With the recent development of the ultrahigh-speed optical time division multiplexed system, high-repetition rate optical-pulse stream generation is necessary. This is different from conventional approaches, which use fiber or integrated waveguide delay line circuits. The high-repetition-rate optical-pulse multiplication phenomenon occurs when the optical pulse's spectral width is greater than the transfer bandwidth of the coupler used. From the analysis, the output repetition rate can be controlled by using fiber couplers with different equivalent transfer bandwidths. The pulse seperation spacing is controlled by number of cascaded coupler in optical loop mirror coupler scheme.