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Predictable Charts 활동이 초등학교 5학년 영어 쓰기 능력 및 학습 태도에 미치는 영향
서형석(Seo, Hyeong Seok),이선(Lee, Sun) 한국초등영어교육학회 2013 초등영어교육 Vol.19 No.4
This study aims to examine the effects of predictable charts to 5th graders of Korean elementary school on their English writing ability and attitude toward writing. Two classes of 56 students participated in this study. For the quantitative analysis, English writing ability tests and questionnaires were administered to the students to measure changes in their writing ability and attitude toward writing. Students in the experimental group also wrote comments about how they thought about the predictable chart activity, which were qualitatively analyzed. The findings of the study are as follows; when comparing English writing test results of the two groups, the mean of experimental group was slightly higher than the control group, however, it was not statistically significant. When comparing attitudinal changes toward English writing, there were no statistically significant differences between the two groups. However, the control group's paired t-test results showed that students in the control group lost interest and confidence in English writing, which was statistically significant. The qualitative analysis results showed that most students thought predictable chart activity made them interested and confident in English writing and they also thought they could learn many new English expressions and sentence patterns through sharing their writings with their peers.
응집 요소를 사용한 균열 진전 유한요소 해석에서 응집 법칙의 영향에 대한 연구
서형석(Hyeong-Seok Seo),백형찬(Hyung-Chan Baek),김현규(Hyun-Gyu Kim) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.4
본 논문에서는 3 점 굽힘과 이중 외팔보 문제에 대하여 응집 요소를 사용한 유한요소 균열 진전 해석을 수행하고 응집 법칙의 영향을 알아보았다. 응집 요소는 ABAQUS/Standard 의 사용자 서브루틴(UEL)으로 구현하였으며 응집 법칙은 다항식 형태의 응집 트랙션-열림 변위의 관계식을 사용하였고 응집 법칙의 형상에 대한 영향을 알아 보기 위하여 다항식의 계수를 변화시켰다. 동일한 파손 에너지와 응집 강도를 갖지만 다른 형상의 응집 법칙에 대한 해석을 수행하고 변위-반력 곡선을 비교하여 균열 진전 거동의 변화를 알아보았다. 또한 요소 크기에 따른 균열 진전 해석 결과의 영향을 논의하였다. In this paper, the effect of cohesive laws on the finite element analysis of crack propagation using cohesive elements is investigated through three-point bending and double cantilever beam problems. The cohesive elements are implemented into ABAQUS/Standard user subroutines(UEL), and the shape of cohesive law is varied by changing parameters in polynomial functions of cohesive traction-separation relations. In particular, crack propagation behaviors are studied by comparing load-displacement curves of the analysis models which have different shapes of cohesive laws with the same values of fracture energy and cohesive strength. Furthermore, the influence of the element size on crack propagation is discussed in this study.
구강암 세포주를 이종 이식한 누드마우스에서 apigenin의 경구투여에 따른 항암효능에 관한 연구
이진석(Jin-Seok Lee),서형석(Hyeong-Seok Seo),김소정(So-Jung Kim),김형진(Hyeong-Jin Kim),김진(Jin Kim),이성호(Seung-Ho Lee),박영석(Young-Seok Park),박병권(Byung-Kwon Park),김병수(Byeong-Soo Kim),김상기(Sang-Ki Kim),정지윤(Ji-Youn Jun 한국생명과학회 2010 생명과학회지 Vol.20 No.10
Apigenin은 과일과 야채에 들어있는 플라보노이드로 다양한 악성 세포에 항증식효과를 보여준다. 세포성장 저해효과를 확인하기 위하여 KB 구강암세포주를 96 well plate에 6×10³ cells/well로 분주하고 24시간 후에 apigenin을 24시간 동안 처치하여 MTT assay를 수행하였다. Apigenin은 배양 후 용량 의존적으로 세포사를 유도하였다. Apigenin 100 μM을 24시간 동안 처치하고 대조군과 세포성장을 비교하였을 때 유의적인 감소를 확인하였다. KB 구강암세포주에서의 apoptosis를 확인하기 위해 DAPI 염색을 수행하였다. Apigenin을 처치한 세포에서 핵의 응축이 존재함을 형광현미경으로 확인하였다. 우리는 누드마우스에 KB 구강암세포주를 이식하여 세포 성장 억제 효과를 알아보았다. Apigenin을 마우스에 25, 50 ㎎/㎏을 0.2 ml의 PBS에 녹여 경구투여 하였다. 종양 사이즈는 대조군과 25, 50 ㎎/㎏ apigenin 투여군을 비교하였을 때 유의적으로 감소하였다. Apoptosis 분석을 위해 TUNEL염색을 수행하였다. 25 ㎎/㎏ apigenin 투여군과 대조군을 비교하였을 때 apoptosis의 유의적인 증가를 확인하였다. 육안적 소견을 위한 H&E 염색은 이상이 없었다. 본 연구는 apigenin이 구강암세포주 성장 억제를 apoptosis의 유도를 통하여 확인하였다. Apigenin (4', 5, 7-trihydroxyflavone), a common dietary flavonoid abundantly present in fruits and vegetables, has shown remarkable anti-proliferative effects against various malignant cell lines. To observe the anti-proliferative effects, oral cavity cancer cell lines, 6×10³ cells/well (96 well plate) of KB oral cavity tumor cells were plated and 24 hr later treated with apigenin for one day, after which MTT assay was performed. Apigenin induced cell death in a dose-dependent manner after incubation. Cell viability was significantly decreased in the group treated with 100 μM apigenin for 24 hr (p<0.05) compared to the control group. To assess apoptosis, the nuclei of KB cells were stained with DAPI. The presence of chromatin condensation in the apigenin treated cells was detected on a fluorescent microscope (×200). We investigated the in vivo growth inhibitory effects of apigenin on oral cavity cancer KB tumor xenograft subcutaneously implanted in male nude mice. Apigenin was administered to mice by gavage at doses of 25 and 50 ㎎/㎏/day in 0.2㎖ of PBS. Tumor volume was significantly decreased in 25 and 50 ㎎/㎏ apigenin-administration groups compared to the control group. For apoptosis analysis, TUNEL staining was performed. A significant increase in TUNEL positive cells was found in the 25 ㎎/㎏ apigenin administration group compared to the non- apigenin administration group. Histopathological changes were not observed. These results indicate that apigenin inhibits oral cavity cancer cell growth through the induction of apoptosis.