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산소와 연소 단원에서 과학적 개념 형성을 위한 수업 전략의 효과
엄상수,고영환,백성혜,박국태 한국교원대학교 과학교육연구소 2000 청람과학교육연구논총 Vol.10 No.1
The purpose of this study was to investigate the effectiveness of teaching strategies for scientific conceptions in the units of oxygen and combustion in elementary school science textbook. 70 elementary school 6th grade students in Seoul participated. They were divided into experimental group and controlled group. Five scientific concepts were adopted from the units of oxygen and combustion in the 6th grade science textbook. Subjects' preconceptions were investigated by pre-questionnaires. A series of 6 instructional sessions based on the teaching strategy of cognitive confliction theory were given to the experimental group. By the end of the instructional session, a post-test was administered to both experimental and controlled groups. There was a statistically significant difference between post-test gains of the experimental and controlled groups. These results support the notion that the teaching strategy was effective for changing from preconceptions to scientific concepts.
산소와 연소 단원에서 과학적 개념 형성을 위한 수업 전략의 효과
엄상수,고영환,백성혜,박국태 한국초등과학교육학회 2000 초등과학교육 Vol.19 No.2
The purpose of this study was to investigate the effectiveness of teaching strategies for scientific conceptions in the units of oxygen and combustion in elementary school science textbook. 70 elementary school 6th grade students in Seoul participated. They were divided into experimental group and controlled group. Five scientific concepts were adopted from the units of oxygen and combustion in the 6th grade science textbook. Subjects' preconceptions were investigated by pre-questionnaires. A series of 6 instructional sessions based on the teaching strategy of cognitive confliction theory were given to the experimental group. By the end of the instructional session, a post-test was administered to both experimental and controlled groups. There was a statistically significant difference between post-test gains of the experimental and controlled groups. These results support the notion that the teaching strategy was effective for changing from preconceptions to scientific concepts.
성제중,서동만,신용훈,엄태건,서동섭 한국비파괴검사학회 2003 학술대회 논문집 Vol.- No.1
Ferromagnetic material like the steel tubes can easily distort eddy current testing signal due to increased magnetic permeability for defects. Because magnetic field of the test probe is affected in an inconsistent way when the material under the testing has permeability. This permeability effect can be reduced by magnetic saturation. In this paper eddy current testing system was developed to detect flaws on the steel tubes. Magnetic saturation probe with helmholtz coil was designed for saturation and inspection of the steel tubes. When using the designed test probe, the relationship between flaw signals and noises was obviously discriminated. Additionally, a high pass filter was included in the eddy current board to minimize noises due to DC magnetic field.
Clinical Aspect of Coronavirus Disease 2019 (COVID-19) on HBV Infected Patient
( Young Kul Jung ),( Gi Hyeon Seo ),( Tae Hyung Kim ),( Sun Young Yim ),( Young-sun Lee ),( Ji Hoon Kim ),( Yeon Seok Seo ),( Hyung Joon Yim ),( Jong Eun Yeon ),( Kwan Soo Byun ),( Soon Ho Um ) 대한간학회 2021 춘·추계 학술대회 (KASL) Vol.2021 No.1
Um, Tae-Il,Kim, Min-Young,Kim, Tae-Eun,Um, Ik-Hwan Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.2
The ${\alpha}$-Effect; Ground state; Transition state; Intramolecular H-bonding; Yukawa-Tsuno plot; Second-order rate constants for aminolysis of 2-chloro-4-nitrophenyl X-substituted-benzoates (1a-h) have been measured spectrophotometrically in 80 mol % $H_2O/20$ mol % DMSO at $25.0^{\circ}C$. The Br${\emptyset}$nsted-type plot for the reactions of 2-chloro-4-nitrophenyl benzoate (1d) with a series of primary amines curves downward, which has been taken as evidence for a stepwise mechanism with a change in rate-determining step (RDS). The Hammett plots for the reactions of 1a-h with hydrazine and glycylglycine are nonlinear while the Yukawa-Tsuno plots exhibit excellent linearity with ${\rho}_X=1.22-1.35$ and ${\gamma}= 0.57-0.59$, indicating that the nonlinear Hammett plots are not due to a change in RDS but are caused by stabilization of substrates possessing an electron-donating group (EDG) through resonance interactions between the EDG and C=O bond of the substrates. The ${\alpha}$-effect exhibited by hydrazine increases as the substituent X changes from a strong EDG to a strong electron-withdrawing group (EWG). It has been concluded that destabilization of hydrazine through the electronic repulsion between the adjacent nonbonding electrons is not solely responsible for the substituent dependent ${\alpha}$-effect but stabilization of the transition state is also a plausible origin of the ${\alpha}$-effect.
( Tae Hyung Kim ),( Hyung Joon Yim ),( Young-sun Lee ),( Young Kul Jung ),( Han Ah Lee ),( Sun Young Yim ),( Ji Hoon Kim ),( Yeon Seok Seo ),( Jong Eun Yeon ),( Kwan Soo Byun ),( Soon Ho Um ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Aims: In chronic hepatitis B (CHB), nucleos(t)ide analogues (NAs) cannot exterminate the virus, and only suppress its proliferation. Thus, even though NAs improve the liver function, the risk of hepatocellular carcinoma (HCC) persists over time. Since a large cohort study which suggested the superiority of tenofovir over entecavir in reducing HCC risk, there is a great deal of controversy in choosing NAs. In this study, we aimed to meta-analyze the published data from Korea to date together with the unpublished data of our institution to derive the robust conclusion. Methods: We searched on-line database and derived 6 publications from Korea. In addition, we investigated 535 treatment- naïve patients with CHB who were first treated with entecavir (n=298) and tenofovir (n=237) between 2008 and 2016 at Korea University Medical Center (Ansan and Guro Hospitals). We used Kaplan-Meier method, Cox regression model, propensity score matching and meta-analysis. Results: From the 6 publications, 9,844 patients were included, 556 developed HCC. From our institutions, HCC was developed in 59 patients during a median follow-up of 21.6 months. After 1:1 propensity score matching, the kind of antiviral agent did not affect the development of HCC (HR, 0.72; 95% CI 0.31-1.71; P=0.46). Combined with the results of six domestic studies, the tenofovir group did not show significant suppression of HCC development compared to the entecavir group (HR, 0.96; 95% CI 0.74-1.25). Conclusions: In a meta-analysis of seven studies of HBV-endemic area including our own institutional data, HCC occurrence was not significantly different between patients with treated with entecavir or tenofovir.
Um, Hae Young,Kong, Hyun Gi,Lee, Hyoung Ju,Choi, Hye Kyung,Park, Eun Jin,Kim, Sun Tae,Murugiyan, Senthilkumar,Chung, Eunsook,Kang, Kyu Young,Lee, Seon-Woo The Korean Society of Plant Pathology 2013 Plant Pathology Journal Vol.29 No.4
Environmental stresses induce several plant pathogenic bacteria into a viable but nonculturable (VBNC) state, but the basis for VBNC is largely uncharacterized. We investigated the physiology and morphology of the copper-induced VBNC state in the plant pathogen Ralstonia solanacearum in liquid microcosm. Supplementation of $200{\mu}M$ copper sulfate to the liquid microcosm completely suppressed bacterial colony formation on culture media; however, LIVE/DEAD BacLight bacterial viability staining showed that the bacterial cells maintained viability, and that the viable cells contain higher level of DNA. Based on electron microscopic observations, the bacterial cells in the VBNC state were unchanged in size, but heavily aggregated and surrounded by an unknown extracellular material. Cellular ribosome contents, however, were less, resulting in a reduction of the total RNA in VBNC cells. Proteome comparison and reverse transcription PCR analysis showed that the Dps protein production was up-regulated at the transcriptional level and that 2 catalases/peroxidases were present at lower level in VBNC cells. Cell aggregation and elevated levels of Dps protein are typical oxidative stress responses. $H_2O_2$ levels also increased in VBNC cells, which could result if catalase/peroxidase levels are reduced. Some of phenotypic changes in VBNC cells of R. solanacearum could be an oxidative stress response due to $H_2O_2$ accumulation. This report is the first of the distinct phenotypic changes in cells of R. solanacearum in the VBNC state.
Molecular discrimination of Panax ginseng species
Um, Jae-Young,Chung, Hwan-Suck,Kim, Hyun-Ju,Kim, Dae-Ki,Shim, Kyung-Shik,Lee, Kang-Yong,Kim, Jeong-Sook,Choi, Tae-Jin,Kim, Nam-Song,An, Nyeon-Hyoung,Lee, Kang-Min,Lee, Young-Mi,Kim, Jeong-Joong Kyung Hee Oriental Medicine Research Center 2000 International journal of oriental medicine Vol.1 No.2
In order to develop convenient and reproducible methods for identification of ginseng drugs at a DNA level, RAPD (randomly amplified polymorphic DNA) and PCR-RFLP (PCR-Restriction fragment length polymorphism) analysis were applied within Panax species. To authenticate Panax ginseng betvyeen Chinese and Korean ginseng population, RAPD analysis were carried out using 20 mer-random primer. The similarity coefficients among the DNA of ginseng plants analyzed were low, ranging from 0.197 to 0.491. In addition, using PCR-RFLP analysis, very different fingerprints were obtained within Korean ginseng plants. These results suggest that these methods are able to authenticate the concerned Panax species. Broader application of this approach to authenticate other morphologically similar medicinal materials is rationalized.