• Plant Biotechnology Reports
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• v.4 no.2
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• pp.117-123
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• 2010

We used a flow cytometer to investigate the variations in endopolyploidy (the frequencies of nuclei with DNA contents equivalent to 4C through 16C) during the short period of the early growing stage in vigorously growing young tissues of maize seedlings. We examined different portions of the root and leaves that had been growing for 7 (day 7) and 13 (day 13) days after germination. Endoreplication showed two opposing phenomena without aging. In one case, the endopolyploidy of the first leaf was higher on day 13 than on day 7. In the latter case, endopolyploidy decreased, as clearly revealed by a comparison of the endopolyploidy of the second leaves and the 160-170 mm portion of the seminal root on days 7 and 13. Endopolyploidy was also lower in the top of the leaf. In roots, endopolyploidy was increased by the exogenous application of abscisic acid for only 1 day. The levels of endopolyploidy increased without an increase in cell size in the roots. These results showed that endoreplication occurs in actively growing and young tissue and that the variation can be induced in the short period examined.

• Radiation Oncology Journal
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• v.30 no.2
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• pp.49-52
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• 2012

Purpose: To evaluate the effectiveness and safety of postoperative radiotherapy for the treatment of keloid scars administered immediately after Cesarean section. Materials and Methods: A total of 26 postpartum patients with confirmed keloids resulting from previous Cesarean sections received either 12 or 15 Gy radiotherapy. The radiotherapy was divided into three 6 MeV electron beam fractions administered during the postpartum period immediately following the final Cesarean section. To evaluate ovarian safety, designated doses of radiation were estimated at the calculated depth of the ovaries using a solid plate phantom and an ionization chamber with the same lead cutout as was used for the treatment of Cesarean section operative scars and a tissue equivalent bolus. Results: In total, the control rate was 77% (20 patients), while six (23%) developed focally elevated keloids (ranging from 0.5 to 2 cm in length) in the middle of the primary abdominal scar. Five patients experienced mild hyperpigmentation. Nonetheless, most patients (96%) were satisfied with the treatment results. The estimated percentage of the applied radiation doses that reached the calculated depth of the ovaries ranged from 0.0033% to 0.0062%. Conclusion: When administered during the immediate postpartum period, postoperative electron beam radiotherapy for repeated Cesarean section scars is generally safe and produces good cosmetic results with minimal toxicity.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.154-162
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• 2005

In this paper, site response analyses were performed based on equivalent linear technique using the shear wave velocity profiles of 162 sites collected around the Korean peninsula. The site characteristics, particularly the shear wave velocities and the depth to the bedrock, are compared to those in the western United States. The results show that the site-response coefficients based on the mean shear velocity of the top 30m ($V_{S30}$) suggested in the current code underestimates the motion in short-period ranges and overestimates the motion in mid-period ranges. Also the current Korean code based on UBC is required to be modified considering site characteristics in Korea for the reliable estimation of site amplification. From the results of numerical estimations, new regression curves were derived between site coefficients ($F_a$ and $F_v$) and the fundamental site periods, and site coefficients were grouped based on site periods in the regions of shallow bedrock. The standard deviations of the proposed method was reasonable compared to site classification based on $V_{S30}$. Finally, new site classification system is recommended based on site periods for regions of shallow bedrock depth in Korea.

• Wind and Structures
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• v.31 no.5
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• pp.473-482
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• 2020

The first-order method for estimating the extreme wind pressure on building envelopes with consideration of the directionality of wind speed and wind pressure is improved to enhance its computational efficiency. In this improved method, the result is obtained directly from the empirical distribution of a random selection of annual maximum wind pressure samples generated by a Monte Carlo method, rather than from the previously utilized extreme wind pressure probability distribution. A discussion of the relationship between the first- and full-order methods indicates that when extreme wind pressures in a non-typhoon climate with a high return period are estimated with consideration of directionality, using the relatively simple first-order method instead of the computationally intensive full-order method is reasonable. The validation of this reasonableness is equivalent to validating two assumptions to improve its computational efficiency: 1) The result obtained by the full-order method is conservative when the extreme wind pressure events among different sectors are independent. 2) The result obtained by the first-order method for a high return period is not significantly affected when the extreme wind speeds among the different sectors are assumed to be independent. These two assumptions are validated by examples in different regions and theoretical derivation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.135-140
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• 2003

As a construction technique is developed recently, the construction space and construction period are considered to important matters. Especially, in case of construction period, several method is proposed for strength control in the construction field. However there are very little strength control models for application of internal condition. The purpose of this study is to develop a strength control model for application of variety internal condition at construction field. The results are as follows ; 1) According to the results of compressive strength of concrete evaluated by logistic curve and proposed curve, proposed curve is applicable of construction field because there is similar relation with logistic curve. 2) It is shown that the construction period is shortened by reduction of the formwork removal time, because a predicted compressive strength of using the new curve is higher than the proposed compressive strength of standard.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.3
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• pp.285-293
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• 2005

This study was aimed at estimation of gas-particle partitioning of polychlorinated biphenyls (PCBs) in ambient air. The samples were collected at urban site in Japan from March 2002 to January 2003. The concentration of total PCBs (from 4 CB to 10 CB) and TEQ (Toxic equivalent) ranged from 62 to $247\;pg/m^3$ and from 2 to $14\;fgTEQ/m^3 $, respectively. The average contribution $(\%)$ of gas phase to total PCBs concentration was above $80\%$, which suggests that in the atmosphere PCBs predominantly existed in the gas phase. The weak correlations between total PCBs concentration and temperature was found. However this result was due to a typhoon during summer and raining during sampling period. The gas-particle partition coefficient (Kp) was obtained as a function of temperature. The partition ratio of gaseous and particulate phase PCBs can be estimated for an arbitrary temperature. The plot of gas/particle partition coefficient (log Kp) vs. sub-cooled liquid vapor pressure $(log\;P_L)$ had reasonable correlations for individual samples but the slope varied among the samples (coefficients of determination for log Kp versus log $P_L$ plot were> 0.76 $(p<0.0001)$, except for 3 samples). As a result, the variations in the slope among the sampling period may be due to change of temperature, raining during sampling period and wind in this study.

• Korean Journal of Health Education and Promotion
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• v.24 no.2
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• pp.93-109
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• 2007

Objectives: The purpose of the study was to examine the effects of experience based menstrual education program on menstrual attitude and menstrual discomfort among female elementary students. Methods: Non-equivalent control group, pre-post test design was utilized for the study. The participants in the study were 122 female elementary students in P city. They were assigned into 2 groups: The experimental group of 62 and the control group of 60. The experience based education program consisted of 5 sessions with 40 minute length. For control group, no treatment was provided during the period. Post-tests were conducted just after the following menstrual period for both experimental and control groups. The data was analyzed using SPSS WIN 12.0 program. The t-tests were used to answer the research questions. Results: There were significant differences in menstrual attitude and menstrual discomfort between experimental and control groups, The students who participated in the program reported more positive attitude to the menstruation and less discomfort during menstrual period than the students who did not participate in the program. Conclusions: Experience based education had a positive influence on menstrual attitude and menstrual discomfort among female elementary students. Further application of the program would be beneficial for the female elementary students. Future research to standardize the program to the broader population is warranted.

• Earthquakes and Structures
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• v.7 no.1
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• pp.83-99
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• 2014

This study is devoted to estimate higher-mode effects for multi-story structures with considering soil-structure interaction subjected to decomposed parts of near-fault ground motions. The soil beneath the super-structure is simulated based on the Cone model concept. Two-dimensional structural models of 5, 15, and 25-story shear buildings are idealized by using nonlinear stick models. The ratio of base shears for the soil-MDOF structure system to those obtained from the equivalent soil-SDOF structure system is selected as an estimator to quantify the higher-mode effects. The results demonstrate that the trend of higher-mode effects is regular for pulse component and has a descending variation with respect to the pulse period, whereas an erratic pattern is obtained for high-frequency component. Moreover, the effect of pulse component on higher modes is more significant than high-frequency part for very short-period pulses and as the pulse period increases this phenomenon becomes vice-versa. SSI mechanism increases the higher-mode effects for both pulse and high-frequency components and slenderizing the super-structure amplifies such effects. Furthermore, for low story ductility ranges, increasing nonlinearity level leads to intensify the higher-mode effects; however, for high story ductility, such effects mitigates.

• Journal of the Korean Society of Visualization
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• v.19 no.3
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• pp.69-76
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• 2021

Printed circuit heat exchanger (PCHE) is a compact heat exchanger with good heat transfer performance, high structure integrity, and reliability over a wide range of temperatures and pressures. Instead of the traditional zigzag and straight shape channel, the sinusoidal shape channel was adopted in this study to investigate the relation of thermal-hydraulic performance and waviness factors (period and amplitude). The local flow characteristics and the heat flux distribution were compared to verify the effects of period and amplitude on heat transfer performance. As the period of channel becomes shorter, the rapid change of the flow direction can produce high flow separation around the corner leading to the disturbance of the boundary layer opposite wall. The nonuniform distribution of flow velocity appeared around the corner positions can promote fluid mixing and lead to higher thermal performance. An evaluation index was used to compare the comprehensive performance of PCHE considering the Nusselt number and Fanning factor. Based on the simulation results, the optimal design parameters of PCHE channel shape were found that the channel with an equivalent bending angle of 15° offers the highest heat flux capacity.

• Journal of Environmental Science International
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• v.24 no.5
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• pp.601-613
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• 2015

On the study of the characteristics and life cycle of mesoscale convective band in type of airmass that occurred in the Honam area from June to September for only 4 years in the period of 2009~2012, 10 examples based on the amount of rainfall with AWS 24 hours/60 minutes rainfalls, Mt. Osung radar 1.5 km CAPPI/X-SECT images and KLAPS data for convective band with heavy rainfall event were selected. There were analyzed and classified by using the convective band with heavy rainfall occurred along the convergence line of sea wind in the form of individual multi-cellular cell and moving direction of convective band appeared in a variety of patterns; toward southwestern (2 cases), northeastern (4 cases), congesting (2 cases), and changing its moving direction (2 cases). The case study dated of the 17th Aug. 2012 was chosen and implemented by sequentially different evolution of its shape along the convergence line of sea wind cell and moving direction of convective band as equivalent potential temperatures at the lower layer have increased to the upper layer 500 hPa, that the individual cells were developed vertically and horizontally through their merger, but owing to divergence caused by weakened rainfall and descending air current, the growth of new cell was inhibited resulting in dissipation of convective cells.