• 한국수정란이식학회지
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• 제25권4호
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• pp.229-235
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• 2010

The MTT assay is one of superior evaluation methods widely used to analyze the viability of metabolically active cell. It can be used to determine the percentage of viable sperm through measurement of the reduction of MTT granules at mitochondria in sperm tail. The purpose of this study is to determine the optimal condition of a simple and easy MTT assay to validate boar sperm viability and compare the accuracy of this test with microscopic examination. The MTT reduction rate for sperm viability were analyzed in microtiter plates (96 well) from 1 hr to 5 hr incubation periods at $37^{\circ}C$ using spectrophotometer (microplate reader) at 550 nm wavelength. The remainder of semen sample was simultaneously examined to compare the correlation of accuracy between MTT assay and other sperm parameters. Those sperm parameters were included the motility, survival rates, membrane integrity, mitochondria activity and acrosome integrity. The OD values of MTT assay (MTT reduction rates) did not greatly change at 1 hr to 5 hr incubation periods in different proportion of live and freeze-killed sperms (dead sperm). The MTT reduction rates or survival rates were decreased according to the different concentration of live and dead sperm. The linear regression at 1 hr and 4 hr incubation periods in sperm MTT assay was y=291.55x-72.176 and y= 180.64x-44.569, respectively. There are high correlation between 1 hr and 4 hr incubation periods (p<0.001). The results of MTT assay and other sperm parameters has a positive correlation (p<0.01 or 0.05). The correlation coefficients for MTT assay was 0.88115 for motility, 0.89868 for survival rates, 0.91722 for membrane integrity and 0.77372 for acrosome integrity, respectively. In conclusion, the MTT assay can be used as a reliable and efficient evaluation method for boar sperm viability. It can be use practical means to evaluate the quality of boar sperm by a fast, inexpensive and easy method.

• 생물환경조절학회지
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• 제29권3호
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• pp.219-230
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• 2020

본 연구는 시설 딸기(Fragaria × ananassa Duch. cv. Maehyang)의 삽목묘 생산을 위해 적절한 배지 및 가습 기간을 구명하기 위해 수행되었다. 2019년 2월에 코이어(CO), 암면(RW), 페놀폼(PF), 유기성형배지(OFM)에 삽수를 삽목하여 0, 3, 6, 9, 12일간 포깅 처리를 하였으며, 2019년 6월에 현장실증 실험으로 코이어(CO), 암면(RW), 페놀폼(PF), 유기성형배지(OFM)에 삽수를 삽목하여 0, 6, 9, 12, 15일간 미스팅 처리를 하였다. 포깅 처리에서 삽목묘의 발근율과 생존율은 포깅 기간이 길어질수록 증가하는 경향을 보였으며, CO 배지에서 9일 이상 포깅 처리하였을 때 발근율과 생존율이 유의적으로 높았다. 미스팅 처리에서 발근율은 CO와 RW 배지에서 9일 이상 미스팅 처리하였을 때, 생존율은 12일 이상 미스팅 처리하였을 때 유의적으로 높았다. 육묘기에 배지 및 가습 처리에 따른 지상부와 지하부의 생육은 유의적인 차이가 없었다. 따라서 발근율과 생존율을 고려하였을 때, CO 배지에서 9일간 가습 처리하는 것이 안정적인 삽목묘의 생산에 유리할 것으로 판단된다.

• 한국초등과학교육학회지:초등과학교육
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• 제36권2호
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• pp.113-128
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• 2017

This study aims to investigate the research trend of elementary environmental education. Thus, author keywords were extracted from a total of 197 academic these related to elementary environmental education during two different periods when detailed goals were applied to the 2007 and 2009 revised curriculums respectively, and then this study analyzed the network of author keywords. The results of this study can be summarized as below. Firstly, as a result of analyzing the frequency of author keywords from academic theses related to elementary environmental education, this study discovered 369 author keywords from the period when detailed goals were applied to 2009 revised curriculum. Out of them, it was found that the keyword, 'climate change education', showed the highest frequency, followed by 'environmental literacy' and 'environmental perception', except such central keywords as 'environmental education' and 'elementary school student'. From the period when detailed goals were applied to the 2007 revised curriculum, a total of 394 author keywords were discovered, and the keyword, 'environmental literacy', showed the highest frequency, followed by 'environmental perception' and 'ESD (education for sustainable development)'. Secondly, as a result of analyzing the network of author keywords, this study found out that in the total number of network connections, average connection degree, density and clique, the period when detailed goals were applied to the 2007 revised curriculum was somewhat higher than the period when detailed goals were applied to the 2009 revised curriculum. As a result of analyzing the centrality of author keywords, this study found out that during both the periods, 'environmental perception' and 'environmental literacy' were high in degree centrality and betweenness centrality, except such central keywords as 'environmental education' and 'elementary school student'. As a result of analyzing the components of author keywords as sub-networks, this study discovered 9 components from the period when detailed goals were applied to the 2009 revised curriculum and 6 components from the period when detailed goals were applied to the 2007 revised curriculum. During both the periods, the largest component was composed of keywords high in degree centrality and betweenness centrality.

• The Korean Journal of Ecology
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• 제24권4호
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• pp.233-237
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• 2001

Changes of the oribatid mite species composition during the litter decomposition was investigated in the north-facing and south-facing slopes with different lower vegetation (annual herbaceous plants in north and perennial Sasa in south) in the altitude 1,000 m of Mt. Jumbong, a nature reserve area in Korea, from August 1994 to September 1995. Total 58 species of oribatid mites were collected. The values of O1son's negative exponential index (k) were -0.56 in the south-facing slope and -0.49 in the north-facing slope, but there was no significant difference between them. The decomposition rate of litter increased rapidly until Oct. 1994, and decreased thereafter. Intensive settlement of the forest litter by oribatid mites was recorded in the autumn periods and it decreased in the next spring and summer. Species diversity index (H'), and species evenness (J') ranged from 1.74 to 2.69, and from 0.57 to 0.93, respectively, and the values were lowest in spring. In the successive periods of growing season, there followed great changes in the structure of species dominance. Heminothrus minor was one of the most dominant species in autumn in the first year when litter were placed, but was never recovered next seasons. In contrast, Platynothrus yamasakii was also dominant in the first autumn, then decreased very low in numbers in next spring and summer, but regained its number in autumn. On the other hand, an increase of the number during these periods was observed by Epidamaeus sp.2. Ceratopia bipilis and Epidamaeus sp.1 were abundant both in the north-and south-facing slopes. Trichogalumna nipponica was only found in the south-facing slope, and Nanhermannia elegantula was only found in the north-facing slope.

• Restorative Dentistry and Endodontics
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• 제45권3호
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• pp.32.1-32.12
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• 2020

Objectives: To evaluate the polymerization efficiency of a matrix-modified bulk-fill composite, and compare it to a conventional composite which has a similar filler system. The degree of conversion (DC%) and monomer elution were measured over different storage periods. Additionally, fillers' content was examined. Materials and Methods: Cylindrical specimens were prepared, in bulk and incrementally, from Filtek Bulk Fill (B) and Filtek Supreme XTE (S) composites using a Teflon mold, for each test (n = 6). Using attenuated total reflection method of Fourier transformation infrared spectroscopy, DC% was measured after 24 hours, 7 days, and 30 days. Using high-performance liquid chromatography, elution of hydroxyethyl methacrylate, triethylene glycol dimethacrylate, urethane dimethacrylate, and bisphenol-A glycidyl dimethacrylate was measured after 24 hours, 7 days and 30 days. Filler content was examined by scanning electron microscopy (SEM). Data were analyzed using 2-way mixed-model analysis of variance (α = 0.05). Results: There was no significant difference in DC% over different storage periods between B-bulk and S-incremental. Higher monomer elution was detected significantly from S than B. The elution quantity and rate varied significantly over storage periods and between different monomers. SEM images showed differences in fillers' sizes and agglomeration between both materials. Conclusions: Matrix-modified bulk-fill composites could be packed and cured in bulk with polymerization efficiency similar to conventional composites.

• Journal of Preventive Medicine and Public Health
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• 제54권1호
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• pp.46-54
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• 2021

Objectives: This study explored the relationship between shift intensity and insomnia among hospital nurses. Methods: The participants were 386 female hospital nurses who underwent a special health examination for night workers in 2015. The Korean Insomnia Severity Index (ISI), indices of shift work intensity, and other covariates such as amount of exercise, level of alcohol consumption, employment duration, and hours worked were extracted from the health examination data. The indices for shift intensity were (1) number of 3 consecutive night shifts and (2) number of short recovery periods after a previous shift, both assessed over the prior 3 months. Multiple logistic regression analysis adjusted for the aforementioned covariates was performed to evaluate the association of shift intensity with insomnia, defined as an ISI score of ≥8. Results: The nurses with insomnia tended to be younger (p=0.029), to have worked 3 consecutive night shifts more frequently (p<0.001), to have experienced a greater number of short recovery periods after the previous shift (p=0.021), and to have worked for more hours (p=0.006) than the nurses without insomnia. Among the other variables, no statistically significant differences between groups were observed. Experiences of 3 or more consecutive night shifts (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.29 to 4.20) and 3 or more short recovery periods (OR, 2.01; 95% CI, 1.08 to 3.73) were associated with increased odds of insomnia. Conclusions: The results suggest that decreasing the shift intensity may reduce insomnia among hospital nurses working rotating shifts.

• 천문학회지
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• 제54권2호
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• pp.61-70
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• 2021

We investigate 20 post-coronal mass ejection (CME) blobs formed in the post-CME current sheet (CS) that were observed by K-Cor on 2017 September 10. By visual inspection of the trajectories and projected speed variations of each blob, we find that all blobs except one show irregular "zigzag" trajectories resembling transverse oscillatory motions along the CS, and have at least one oscillatory pattern in their instantaneous radial speeds. Their oscillation periods are ranging from 30 to 91 s and their speed amplitudes from 128 to 902 km s-1. Among 19 blobs, 10 blobs have experienced at least two cycles of radial speed oscillations with different speed amplitudes and periods, while 9 blobs undergo one oscillation cycle. To examine whether or not the apparent speed oscillations can be explained by vortex shedding, we estimate the quantitative parameter of vortex shedding, the Strouhal number, by using the observed lateral widths, linear speeds, and oscillation periods of the blobs. We then compare our estimates with theoretical and experimental results from MHD simulations and fluid dynamic experiments. We find that the observed Strouhal numbers range from 0.2 to 2.1, consistent with those (0.15-3.0) from fluid dynamic experiments of bluff spheres, while they are higher than those (0.15-0.25) from MHD simulations of cylindrical shapes. We thus find that blobs formed in a post-CME CS undergo kinematic oscillations caused by fluid dynamic vortex shedding. The vortex shedding is driven by the interaction of the outward-moving blob having a bluff spherical shape with the background plasma in the post-CME CS.

• Journal of Pharmaceutical Investigation
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• 제25권3호spc1호
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• pp.33-35
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• 1995

Microspheres containing tetracaine or bupivacaine with poly-lactic-glycolic acid were prepared with a range of compositions. Using the rat scicatic nerve model in vivo it was found that prolonged blockade for periods of 2-7 days. depending on composition variables. Polymer-local anesthetics microspheres are feasible delivery vehicle for prolonged regional nerve blockade.

• Korean Journal of Mathematics
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• 제15권1호
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• pp.71-78
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• 2007

We consider arrival process and ON/OFF source model which allows for long packet trains and long inter-train distances. We prove the weak convergence of theses processes to Fractional Brownian motion. Finally, we figure out the coefficients of $B_H(t)$ and time $t$ when ON/OFF periods have the Pareto distribution.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 하계학술발표대회
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• pp.145-145
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• 2005