• Journal of the Korean Wood Science and Technology
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• 제15권2호
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• pp.105-112
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• 1987

대기오염(大氣汚染)이 극심한 것으로 알려져있는 온산(溫山) 및 여천(麗川) 지역의 소나무 (Pinus densiflor)를 대상수종으로, 해부학적 특성을 조사하였던 바, 지난 10년간 전반적인 생장의 감소를 확인할 수 있었으며, 이 생장감소의 시작년대와 상기(上記)지역에서의 공단(工團)의 가동 년도(年度)가 거의 일치하고 있음을 연륜년대학적(年輪年代學的) 고찰을 통해 입증할 수 있었다. 대기오염 피해지역의 소나무에 있어서 반경방향의 생장의 감소는 지난 10년간 온산(溫山)의 경우 70%, 여천(麗川)의 경우 60%에 달하였다. 이들 소나무는 춘재(春材)의 형성이 억제된 반면 피해기간 중의 추재율(秋材率)은 약 30% 정도 증가되었다. 대기오염 피해기간중 형성된 연륜내(年輪內)의 최대밀도(最大密度)는 건전재의 그것에 비해 약간 낮게 나타났다. 가도관의 치수의 경우 가도관장(假導官長)의 변이(變異)는 찾아볼 수 없었으나, 피해기간중 가도관벽(壁)의 두께와 그 직경은 감소하였다. 이같은 변화에도 불구하고 미시구조(微視構造)의 관찰결과, 하등의 이상조직(異常組織)이나 미생물(微生物)을 발견(發見)할 수 없었다.

• 한국수산과학회지
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• 제31권1호
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• pp.71-76
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• 1998

C. polykrikoides의 항생제에 대한 특이성을 알아보기 위해 C. polykrikoides의 항생제에 대한 $50\%$ 생존시간을 조사하였다. C. polykrikoides는 tetracycline과 thlorarnphe-nicol에 대해서는 아주 민감하였고, polymixin-B, ampicil-lin, penicillin-G, dihydrostreptomycin, neomycin에 대 해 서 는 저항성이 큰 선택적 특이성을 가졌다. C. polykrikoides에 민감한 항생제인 tetracycline과 chloramphenicol의 경우는 사멸곡선을 분석하여 사멸에 영향을 주지 않는 농도를 확인했으며, 또한, 농도에 따른 C. polykrikoidess에 대한 항생제의 작용특성을 분석하였다. 박테리아에 오염된 C. polykrikoides 배양액을 percoll 원심분리로 박테리아를 제거하기 전에 C. polykrikoides에 저항성이 큰 항생제에 대한 박테리아 군집의 감수성 시험을 행하여 박테리아 제거를 위한 적당한 항생제와 농도를 결정 한 뒤, percoll 원심분리로 박테리아와 곰팡이를 제거하고, 조체를 회수한 후, 남아있는 소량의 박테리아를 감수성이 큰 항생제를 연속적으로 처리 (antibiotic cascade)하여 C. polykrikoides의 순수배양(axonic culture)이 가능하게 되었다. 순수배양한 C. polykrikoides은 밀도가 약 740cells/ml 이상에서 대수증식기에 접어들었고 최대 5,800cells/ml까지 증식하였다. C. polykrikoides의 하루당 분열율 k 값은 저밀도 세포 상태에서 아주 정확한 증식지표를 제시하였고, 대수증식기 전에 반드시 최대의 k 값 변화를 가진 세포의 밀도가 존재하였으며, 우리는 이 최대 k 값 변화를 가진 밀도를 정확한 적조 예보와 초기에 적조제어를 위한 모델로서 사용될 수 있음을 제시한다. 결론적으로 본 연구에서 확립된 C. polykrikoides의 순수분리에 의한 배양방법은 C. polykrikoides 뿐만 아니라 다른 적조 생물의 독성학적, 면역학적, 생화학적, 생태학적, 분자생물학적 연구를 위해 편리하게 이용할 수 있을 것이다.

• Structural Engineering and Mechanics
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• 제32권3호
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• pp.459-475
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• 2009

This paper presents analytical methodologies for remaining life prediction of plain concrete structural components considering tension softening and size effects. Non-linear fracture mechanics principles (NLFM) have been used for crack growth analysis and remaining life prediction. Various tension softening models such as linear, bi-linear, tri-linear, exponential and power curve have been presented with appropriate expressions. Size effect has been accounted for by modifying the Paris law, leading to a size adjusted Paris law, which gives crack length increment per cycle as a power function of the amplitude of a size adjusted stress intensity factor (SIF). Details of tension softening effects and size effect in the computation of SIF and remaining life prediction have been presented. Numerical studies have been conducted on three point bending concrete beams under constant amplitude loading. The predicted remaining life values with the combination of tension softening & size effects are in close agreement with the corresponding experimental values available in the literature for all the tension softening models.

• Journal of Plant Biology
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• 제35권4호
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• pp.425-429
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• 1992

Ranunculus sceleratus 엽병의 세포 신장은 에틸렌에 의하여 촉진되는 것으로 알려져 있다. 오옥신을 처리한 엽병조직 절편에서 spermine은 세포 신장과 에틸렌의 생성을 비슷한 양상으로 억제하였다. Spermine 농도에 대한 오옥신 유도 에틸렌 생성 억제반응은 ACC에 의한 에틸렌 생성의 경우도 유사한 양상을 나타내었으며 이는 폴리아민이 ACC가 에틸렌으로 전환되는 과정을 억제한다는 것을 시사한다. 오옥신 유도 에틸렌 생성은 폴리아민 생합성 억제제인 DFMA아 DFMO에 의하여 각각 현저하게 촉진되었으며 DFMA에 의한 에틸렌 생성의 증가는 spermine을 고농도로 처리하므로써 완전히 소멸되는 결과를 얻었다. 이러한 결과들은 오옥신과 에틸렌에 대한 Ranunculus의 세포성장 반응에서 내생 폴리아민이 조절 역할을 수행한다는 가능성을 입증하는 것이다.

• Journal of Nutrition and Health
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• 제37권8호
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• pp.655-661
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• 2004

This study was performed to investigate the antimicrobial effect of the Pulsatilla koreana extracts against food-borne pathogens. First, the Pulsatilla koreana was extracted with methanol at room temperatures, and fractionation of the methanol extracts from Pulsatilla koreana was carried out by using petroleum ether, chloroform, and ethyl acetate, and methanol respectively. The antimicrobial activity of the Pulsatilla koreana extracts was determined using a paper disc method against food-borne pathogens and food spoilage bacteria. The ethyl acetate extracts of Pulsatilla koreana showed the highest antimicrobial activity against Staphylococcus aureus, Salmonella enteritidis and Shigella dysenteriae. The Staphylococcus aureus and Shigella dysenteriae were inhibited by petroleum ether and chloroform extracts of Pulsatilla koreana as well as ethyl acetate extracts of Pulsatilla koreana. The synergistic effect has been found in combined extracts of Pulsatilla koreana and Portulaca oleracea as compared to each extracts alone. Finally, the growth inhibition curve was determined using ethyl acetate extracts of Pulsatilla koreana against Staphylococcus aureus and Shigella dysenteriae. The ethyl acetate extract of Pulsatilla koreana showed strong antimicrobial activity against Staphylococcus aureus at the concentration of 2,000 ppm. The 2,000 ppm of ethyl acetate extract from Pulsatilla koreana retarded the growth of S. aureus more than 12 hours and Shigella dysenteriae up to 9 hours.

• 소성∙가공
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• 제8권5호
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• pp.471-481
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• 1999

The properties of deformed products are generally dependent upon the distribution of microstureture. It is, therefore, necessary to make the distribution of microstureture uniform in order to achieve the best balance of properties in the final product. This is often a demanding task, even for conventional materials. It is become essential to achieving mechanical integrity and a desired combination of microstructure and properties. The objective mechanical integrity and a desired combination of microsttucture and properties. The objective of this study is to design the optimal die profile which can yield more uniform microstructure in hot extruded product. The microstructure evolution, such as dynamic and static recrystallization as well as grain growth, is investigated using the program com-bined with yada and Senuma's empirical equations and rigid-thermoviscoplastic finite element method. The die profile of hot extrusion is represented by Bezier-curve to define all available profile. In order to obtain the optimal die profile which yields uniform microstructure in the product the FPS(Flexible Polyhedron Search) method is applied to the present study. To validate the result of present study the experimental hot extrusion is performed and the result is compared with that of simulation.

• Human Ecology Research
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• 제54권6호
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• pp.565-574
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• 2016

This research examined the trajectories of peer rejection in preschool children. This study also investigated the gender differences in the intercept and slope of the trajectories for peer rejection along with the influences of aggression, withdrawal and language ability on the trajectories of peer rejection. A latent growth curve model investigated peer rejection in 3 to 5 year olds. Three hundred and thirteen 3-year-old children were recruited from five preschools and 14 daycare centers. The children's language ability was measured by a Wechsler Preschool and Primary Scale of intelligence verbal test and teachers completed measurements for aggression and withdrawal. A peer nomination inventory was used to assess peer rejection. Children were asked to nominate three classmates who they do not like to play with. The research findings showed that peer rejection decreased during the preschool years. Compared with girls, boys showed higher levels of peer rejection and a slower change rate of peer rejection. Girls who were aggressive showed high levels of peer rejection and a slow change rate of peer rejection. Moreover, girls who had a high levels language showed low levels of peer rejection and a slow change rate of peer rejection. These findings imply that language ability could be a protective factor of peer rejection for girls.

• International Journal of Oral Biology
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• 제38권2호
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• pp.81-85
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• 2013

There are estimated to be about 700 species of bacteria in the oral cavity. Based on epidemiological investigations, some of these strains have been proposed as the pathogens responsible for oral diseases such as dental caries, gingivitis and periodontitis. Since electrolyzed hydrogen-rich water has been shown to have beneficial effects on human immunity, its use has increased. In our study, the antibacterial activity of hydrogen-rich water for oralagainst bacteria associated with oral disease was evaluated. The bacterial strains Streptococcus mutans, Fusobacterium nucleatum, Porphyromonas gingivalis and Tannerella forsythia were cultured in specific growth medium. S. mutans, F. nucleatum and P. gingivalis were soaked to thein both hydrogen water and tap water for 30 sec and then inoculated onto mitis-salivarius agar and brain heart infusion agar including supplemented withvitamin K and hemin, respectively. The numbers of bacterial colonies were then measured after cultivation for 48 hours. In the case of T. forsythia, which does not grow well on agar plates, inoculations into modified new oral spirochete (NOS) broth were performed and growth curve analysis was undertaken every day with a spectrophotometer. Hydrogen water showed antibacterial activity against all four bacterial strains in comparison with tap-water. We conclude from this that hydrogen water may have a positive impact on oral hygiene by helping to remove cariogenic bacteria and periodontopathogens.

• 아동학회지
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• 제36권4호
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• pp.91-110
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• 2015

In upper elementary period school adjustment and the effect of parenting face a new set of dynamics. We assumed that parental supervision, affection, incoherence, over-expectation, over-interruption and logical explanation would have an effect on individual trajectories in the development of school adjustment. Additionally, we hypothesized that this model would be different among boys and girls. In this study we analyzed three waves of data collected from 2,378 children nationwide in South Korea. This data was gathered from the Panel Study of Korean Youth and Adolescents conducted by the National Youth Policy Institute(NYPI). Growth-curve longitudinal analysis was conducted and the results indicate that levels of school adjustment had decreased through the $4^{th}$ to $6^{th}$ grade. Parents' supervision, affection and logical explanation significantly predict children's initial school adjustment as well as their rate of decrease in their levels of school adjustment. Parents' supervision had a positive effect on girls' school adjustment. Parents' over-expectation had negative effect on boys' school adjustment levels. Policy implications and future directions for research were also discussed.

• Horticulture, Environment, and Biotechnology : HEB
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• 제59권6호
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• pp.827-833
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• 2018

Plasma lighting systems have been engineered to simulate sunlight. The objective of this study was to determine the effects of plasma lighting on tomato plant growth, photosynthetic characteristics, flowering rate, and physiological disorders. Tomato plants were grown in growth chambers at air temperatures of $25/23^{\circ}C$ (light/dark period), in a $16h\;day^{-1}$ light period provided by four different light sources: 1 kW and 700 W sulfur plasma lights (1 SPL and 0.7 SPL), 1 kW indium bromide plasma light, and 700 W high pressure sodium lamp (0.7 HPS) as a control. The totaldry weight and leaf area at 0.7 SPL were approximately 1.2 and 1.3 times greater, respectively, than that of 0.7 HPS at the 62 days after sowing (DAS). The maximum light assimilation rate was observed at 1 SPL at the 73 DAS. In addition, the light compensation and saturation points of the plants treated with plasma lighting were 98.5% higher compared with HPS. Those differences appeared to be related to more efficient light interception, provided by the SPL spectrum. The percentage of flowering at 0.7 SPL was 30.5%, which was higher than that at 0.7 HPS; however, there were some instances of severe blossom end rot. Results indicate that plasma lighting promotes tomato growth, flowering, and photosynthesis. Therefore, a plasma lighting system may be a valuable supplemental light source in a greenhouse or plant factory.