• Nuclear Engineering and Technology
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• v.51 no.7
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• pp.1828-1834
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• 2019

The performance of a plastic scintillator for use in an in situ measurement system was analyzed using simulation and experimental methods. The experimental results of four major pure beta-emitting radionuclides, namely $^3H$, $^{14}C$, $^{32}P$, and $^{90}Sr/^{90}Y$, were compared with those obtained using a Monte Carlo N-particle (MCNP) code simulation. The MCNP simulation and experimental results demonstrated good agreement for $^{32}P$ and $^{90}Sr/^{90}Y$, with a relative difference of 1.95% and 0.43% between experimental and simulation efficiencies for $^{32}P$ and $^{90}Sr/^{90}Y$, respectively. However, owing to the short range of beta particles in water, the efficiency for $^{14}C$ was extremely low, and $^3H$ could not be detected. To directly measure the low-energy beta radionuclides considering their short range, a system where the source could flow directly to the scintillator was developed. The optimal thickness of the plastic scintillator was determined based on the suggested diameter. Results showed that the detection efficiency decreases with an increase in the depth of the water. The detection efficiency decreased drastically to approximately 10 cm, and the tendency was gradually constant.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.2
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• pp.142-147
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• 2021

We present a subthreshold swing model for a symmetric junctionless double gate MOSFET. The scale length λ1 required to obtain the potential distribution using the Poisson's equation is a criterion for analyzing the short channel effect by an analytical model. In general, if the channel length Lg satisfies Lg > 1.5λ1, it is known that the analytical model can be sufficiently used to analyze short channel effects. The scale length varies depending on the channel and oxide thickness as well as the dielectric constant of the channel and the oxide film. In this paper, we obtain the scale length for a constant permittivity (silicon and silicon dioxide), and derive the relationship between the scale length and the channel length satisfying the error range within 5%, compared with a numerical method. As a result, when the thickness of the oxide film is reduced to 1 nm, even in the case of Lg < λ1, the analytical subthreshold swing model proposed in this paper is observed to satisfy the error range of 5%. However, if the oxide thickness is increased to 3 nm and the channel thickness decreased to 6 nm, the analytical model can be used only for the channel length of Lg > 1.8λ1.

• Geomechanics and Engineering
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• v.36 no.2
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• pp.157-166
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• 2024

Generally, the rubble mound installed on the slope embankment of the open-type wharf is designed based on the impact of wave force, with no consideration for the impact of seismic force. Therefore, in this study, dynamic centrifuge model test results were analyzed to examine the acceleration amplification of embankment reinforced with rubble mound under seismic conditions. The experimental results show that when rubble mounds were installed on the ground surface of the embankment, acceleration response of embankment decreased by approximately 22%, and imbalance in ground settlement decreased significantly from eight to two times. Furthermore, based on the experimental results, one-dimensional site response (1DSR) analyses were conducted. The analysis results indicated that reinforcing the embankment with rubble mound can decrease the peak ground acceleration (PGA) and short period response (below 0.6 seconds) of the ground surface by approximately 28%. However, no significant impact on the long period response (above 0.6 seconds) was observed. Additionally, in ground with lower relative density, a significant decrease in response and wide range of reduced periods were observed. Considering that the reduced short period range corresponds to the critical periods in the design response spectrum, reinforcing the loose ground with rubble mound can effectively decrease the acceleration response of the ground surface.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.8 s.179
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• pp.1885-1898
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• 2000

Welding quality is closely related to the arc state. So, it is very important to estimate the arc state in real time. In the short circuit transfer region of CO2 are welding, the spatter , as it is well known, is mainly generated on an instance of short circuit or on an instance that the are is ignited after short circuit, or on the cases of an instantaneous short circuit. If the short circuit period or the arc time is irregular, the spatter is generated more than it is regular. Thus there is a close relationship of the amount of the spatter generation with the arc stability. In this paper, to develop the index for estimating the arc stability in short circuit transfer range Of CO2 arc welding, the welding current and are voltage waveforms were measured and the spatter generated was captured and measured. The correlation analysis of the measured amount of the spatter with the factors (the components and the standard deviations of the components) was performed, and the factors that have a considerable influence on the spatter generation among all factors were selected. And some cases of models consisted of the factors were presented, and a mathematical index model which can make an estimation the amount of the spatter from these models with multiple regression analysis. Also, it was compared how much the amount of the spatter generated under the selected welding conditions do these index models fit, and the index model to estimate the arc stability which represent the spatter generation most appropriately was developed

• Korean Journal of Medicinal Crop Science
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• v.26 no.6
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• pp.471-476
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• 2018

Background: Astragalus membranaceus belonging to the Leguminosae family is often utilized as a traditional medicine. The aim of this study was to elucidate the basic breeding information required to develop short stem A. membranaceus cultivars. Methods and Results: Roots of A. membranaceus advanced yield trial (AYT) lines were harvested in late October 2017. Root yield of six AYT lines were increased in a range of 8.9 - 74.8% compared with 'Aseong' as control (check variety). The height of seven AYT lines were shorter than that of 'Aseong'. In addition, stem diameter of nine AYT lines was thicker than that of 'Aseong'. Consequently, 1502-56, 1503-90, and 1510-80 were selected as elite lines for the development of short stem cultivars. HPLC analysis was perfromed to identify lines with high level active components such as calycosin-7-O-${\beta}$-D-glucoside and calycosin. The levels of both active components were higher in 1502-56, and 1503-90, but not in 1510-80 compared to 'Aseong'. In addition, 2,2-Diphenyl-1-picryl hydrazyl (DPPH) radical scavenging activity was higher in the 1502-56 compared to 'Aseong'. Considering these results, two AYT lines, 1502-56 and 1503-90 were selected as short stem lines with high calycosin-7-O-${\beta}$-D-glucoside and calycosin content. Conclusions: Taken together, Two short stem lines were identified in this study. In our future study, regional yield trial (RYT) will be conducted using these selected lines to develop new cultivars.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.575-583
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• 2003

In thesis we applied the short or open reflection type for IQ vector modulator The open or short type is operated even exception of other redundancy circuit. Generally IQ vector modulator uses MESFET in performing reflection open or short, then minus voltage which is having complex structure is required to operate MESFET via IQ signal. However BJT can be substituted for MESFET, BJT is improved characteristics like as cutoff frequency, electron mobility and so on. We used BJT in IQ vector modulator which is compatible with TTL level in I,Q digital signal, and attached AGC function. We got the result of operations within ${\pm}$ 1$^{\circ}$ phase and ${\pm}$ 0.6 dB amplitude Variation With full range of 20 dB and Variation of ${\pm}$ 6$^{\circ}$ Phase and ${\pm}$ 0.5 dB amplitude Versus full temperature range.

• Radiation Oncology Journal
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• v.31 no.4
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• pp.216-221
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• 2013

Purpose: The purpose of this retrospective study was to evaluate the efficacy and feasibility of short-course hypofractionated radiotherapy (RT) for the palliation of uterine cervical cancer. Materials and Methods: Seventeen patients with cancer of the uterine cervix, who underwent palliative hypofractionated 3-dimensional conformal radiotherapy between January 2002 and June 2012, were retrospectively analyzed. RT was delivered to symptomatic lesions (both the primary mass and/or metastatic regional lymph nodes). The total dose was 20 to 25 Gy (median, 25 Gy) in 5 Gy daily fractions. Results: The median follow-up duration was 12.2 months (range, 4 to 24 months). The median survival time was 7.8 months (range, 4 to 24 months). Vaginal bleeding was the most common presenting symptom followed by pelvic pain (9 patients). The overall response rates were 93.8% and 66.7% for vaginal bleeding control and pelvic pain, respectively. Nine patients did not have any acute side effects and 7 patients showed minor gastrointestinal toxicity. Only 1 patient had grade 3 diarrhea 1 week after completion of treatment, which was successfully treated conservatively. Late complications occurred in 4 patients; however, none of these were of grade 3 or higher severity. Conclusion: Short-course hypofractionated RT was effective and well tolerated as palliative treatment for uterine cervical cancer.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1047-1053
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• 2011

In this paper, we proposed an HF-band wireless power transfer system with adaptive frequency control circuit for efficiency enhancement in a short range. In general, a wireless power transfer system shows an impedance mismatching due to a reflected impedance, because a coupling coefficient is varied with respect to separation distance between two resonating loop antennas. The proposed method can compensate this impedance mismatching by varying input frequency of a voltage-controlled oscillator adaptively with respect to separation distance. Therefore, transmission efficiency is enhanced in a short distance, where large impedance mismatch occurs. The adaptive frequency circuit consists of a directional coupler, a detector, and a loop filter. In order to demonstrate the performance of the proposed system, a wireless power transfer system with adaptive frequency control circuits is designed and implemented, which has a pair of loop antennas with a dimension of 30${\times}$30 $cm^2$. From measured results, the proposed system shows enhanced efficiency performance than the case without adaptive frequency control.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.394-399
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• 2006

In this paper, we investigated performance for 5.8GHz dedicated short range communication system using OFDM which will be applied to Intelligent transportation system services. The maximum speed of a vehicle in DSRC channel is very fast as 180km/h, so a service time is very short to serve a various traffic information if hand-off is not occurred. Therefore higher bit rate is required to proved advanced and intelligent service to the drivers of various vehicle and the data transmission rate of the next generation DSRC system if being promoted over 10Mbps. The signals received in Clarke & Gans channel have been simulated using the computer simulator.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.8
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• pp.1090-1098
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• 2018

Many short range weather radars with the low elevation search capability are needed for analysis and prediction of unusual weather changes or rainfall phenomena which occurs regionally. However, due to the characteristics of low elevation electromagnetic wave beam, it is highly probable that the received weather signals of these radars are seriously contaminated by the ground clutter. Therefore, the filter removing low Doppler frequency band is generally used to mitigate this problem. However, the phase noise in a radar system may limit the removal of the strong clutter and this may cause serious problems in estimating weather parameters because of the remaining clutter. Therefore, in this paper, the characteristics of phase noise in a radar system are investigated and the effects of the system phase noise are analyzed in the improvement of signal to clutter ratio for the strong clutter environment such as a short and low-elevated weather radar.