• Journal of The Korean Association For Science Education
• /
• v.20 no.3
• /
• pp.468-478
• /
• 2000

In this study, the effects of a teaching strategy based on interactive formative assessment on students' science concept understandings and science-related attitudes were investigated. Students' perceptions toward this teaching strategy were also examined. Eight classes chosen from a co-ed middle school in Seoul. Four classes were assigned to the experimental group and the other four classes were assigned to the control group. After the instructions, tests regarding students' conceptions and science-related attitudes were administered. We also interviewed 24 students randomly chosen from the experimental group to investigate their perceptions toward the teaching strategy used. The results showed that the teaching strategy used was more effective for enhancing students' science concept understandings. However, there was no significant difference in science-related attitudes between the two groups. For the experimental group, no significant differences were found in the gain scores of the conceptions tests between the subgroups by previous achievement or cognitive levels. From interviews, it was found that students thought that the teaching strategy used encouraged much interactions and motivated them to think, and that teacher's appropriate feedbacks were helpful to their understanding scientific concepts.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.4
• /
• pp.734-739
• /
• 2005

Myxobacterium sp. HK1, isolated from Korean soil, degrades cellulose, differentiates to fruiting body, and its 16s rDNA has $95\%$ similarity to Polyangium sp. An anticancer molecule, CDMHK, was identified from culture broth of Myxobacterium sp. HK1, and purified by Diaion HP20, Silica gel, Sephadex LH-20 chromatography, and preparative HPLC using an YMC OSD-A C18 column. The molecular structure and formula were determined to be $C_{l2}H_{l9}N_3O_2$ (M.W 237) by MS spectrometry, 300 MHz $^{1}H\;and\;^{13}C$ NMR. The CDMHK was not active against Escherichia coli, Staphylococcus aureus, and Candida albicans. However, this molecule inhibited the growth of various cancer cell lines. The $ED_{50}$ values of CDMHK were determined to be 0.147, 0.086, 0.18, 0.166, and 0.142 $\mu$g/ml against A549, SK-OV-3, SK-MEL-2, VF498, and HCTl5 cancer cell lines, respectively. In addition, the CDMHK was able to induce apoptosis of the CCRF-CEM cancer cell line, evidenced by DNA fragmentation assay and DAPI staining.

• Journal of Conservation Science
• /
• v.20
• /
• pp.105-117
• /
• 2007

This study is examined the beads excavated in the Sacheon Neukdo ruins to investigate the features of archaeological chemistry and to compare those of the same type of beads excavated within the Gyeongsang-do area by means of scientific analysis. The samples have been observed the micro-structures by an optical microscope and SEM and confirmed the physical property by density measurement. Chemical property have been analyzed main components such as flux, stabilizers, and colorants by SEM-EDS. Besides, XRD was used to identified the characteristic materials of beads. The white opaque beads, which was initially estimated as sea-shell beads, confirm as amorphous silica material. The glass beads, which are blue type as a result of compositional analysis, it is revealed potash glass group and LCA(Low-CaO, $Al_2O_3$) system. gB ones are revealed only in LCA-A(LCA-CaO<$Al_2O_3$), while purple blue ones in LCA-B(LCA-CaO>$Al_2O_3$).

• Applied Biological Chemistry
• /
• v.49 no.1
• /
• pp.21-24
• /
• 2006

A series of cytotoxic activities $(ED_{50})$ in vitro against six human cancers (lung cancer, uterine cancer, skin cancer, brain cancer, colon cancer and adenocarcinoma) and their seventeen cell lines of 3,6-bis(2'-pyridyl)pyridazine, 1, 3,6-bis-(6'-methyl-2'-pyridyl)pyridazine, 2 and their transition metal, Ni(II), Cu(II) and Zn(II) complexes, $3{\sim}6$ were measured. Particularly, the results revealed that the cytotoxic activities against the brain cancer cell line (SNB-19) and the colon cancer cell line (SW62) of bis- [3,6-bis-(6'-methyl-2'-pyridyl)pyridazine-$k^2N^2,N^3$]chlorocopper(II)perchlorate, 4 were shown to be higher than that of the first generation anticancer agent, Cis-platin.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.366-372
• /
• 2018

The purpose of this study was to investigate the effects of educational evaluation with the application of flipped learning on undergraduate students' self-directed learning ability (cognitive domains, motive domains, conductive domains) and cognitive learning competency (knowledge and thought, creation, problem solving). An educational evaluation class, which applied flipped learning designed on the basis of pre-class, in-class, and post-class, was taught to 57 undergraduate students for twelve of the sixteen weeks of a semester. It was held each week on Thursdays for two (Ed- I don't understand 'for two'). The study results showed that, applying the flipped learning educational education class for undergraduate students improved self-directed learning ability (motivation domains, behavior domains) and cognitive learning competence (higher order thinking, metacognition, creativity tendency, problem-solving process). This study provides meaningful suggestions on exploring instructional design and effective teaching and learning methods applied to flipped learning.

• Journal of Korean Ophthalmic Optics Society
• /
• v.15 no.4
• /
• pp.313-317
• /
• 2010

Purpose: The purpose of this study was to investigate the surface characteristics of plasma electrolytic oxidation (PEO) surface treatment on AZ31 magnesium alloy eyeglass frames. Methods: The plasma electrolytic oxidation (PEO) surface was created by varying the DC voltage. The oxidation layer of coating was measured using phase analysis by X-ray diffraction. The microstructural morphology was observed using a scanning electron microscopy. Coating layer and the concentration of elements were investigated using the energy dispersive X-ray spectra. Results: The MgO XRD peak was increased as the voltage increased, and the density of the surface oxide film was also increased. The changes in the composition of the EDS also showed a good agreement. Conclusions: The compound oxide crystallization of PEO oxide film layer was done by increasing formation of MgO as the voltage increased. The treatment at 65V and 60 sec showed the best results at surface state, contact angles and salt spray test.

• Korean Chemical Engineering Research
• /
• v.48 no.1
• /
• pp.98-102
• /
• 2010

Magnolia kobus leaf extract was used for the synthesis of bimetallic Au core-Ag shell nanoparticles. Gold seeds and silver shells were formed by first treating aqueous solution of $HAuCl_4$ and then $AgNO_3$ with the plant leaf extract as reducing agent. UV-visible spectroscopy was monitored as a function of reaction time to follow the formation of bimetallic nanoparticles. The synthesized bimetallic nanoparticles were characterized with transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), and X-ray photoelectron spectroscopy(XPS). TEM images showed that the bimetallic nanoparticles are a mixture of plate(triangles, pentagons, and hexagons) and spherical structures. The atomic Ag contents of the bimetallic Au/Ag nanoparticles determined from EDS and XPS analysis were 34 and 65 wt%, respectively, suggesting the formation of bimetallic Au core-Ag shell nanostructure. This core-shell type nanostructure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules.

• Journal of radiological science and technology
• /
• v.43 no.1
• /
• pp.9-14
• /
• 2020

Commercial plate bolus is generally used for treatment of surface tumor and required surface dose. We fabricated 3D-printed bolus by using 3D printing technology and usability of 3D-printed bolus was evaluated. RT-structure of contoured plate bolus in the TPS was exported to DICOM files and converted to STL file by using converting program. The 3D-printed bolus was manufactured with rubber-like translucent materials using a 3D printer. The dose distribution calculated in the TPS and compared the characteristics of the plate bolus and the 3D printed bolus. The absolute dose was measured inserting an ion chamber to the depth of 5 cm and 10 cm from the surface of the blue water phantom. HU and ED were measured to compare the material characteristics. 100% dose was distributed at Dmax of 1.5 cm below the surface when was applied without bolus. When the plate bolus and 3D-plate bolus were applied, dose distributed at 0.9 cm and 0.8 cm below the surface of the bolus. After the comparative analysis of the radiation dose at the reference depth, differences in radiation dose of 0.1 ~ 0.3% were found, but there was no difference dose. The usability of the 3D-printed bolus was thus confirmed and it is considered that the 3D-printed bolus can be applied in radiation therapy.

• The Korean Journal of Applied Statistics
• /
• v.23 no.3
• /
• pp.533-543
• /
• 2010

Asking sensitive questions by a direct survey method causes non-response bias and response bias. Non-response bias arises from interviewees refusal to respond and response bias arises from giving incorrect responses. To rectify these biases, Warner (1965) introduced a randomized response model which is an alternative survey method for socially undesirable or incriminating behavior questions. The randomized response model is a procedure for collecting the information on sensitive characteristics without exposing the identity of the respondent. Many survey researchers have proposed diverse variants of the Warner randomized response model and applied their model to collect the information of sensitive questions. Using an optimal allocation, we proposed three-stage stratified randomized response technique which is an extension of the Kim and Elam (2005) two-stage stratified randomized response technique. In this study, we showed that the estimator based on the proposed response model is more efficient than Kim and Elam (2005). But by adding one more survey step to the Kim and Elam (2005), our proposed model may have relatively less privacy protection compared to the Kim and Elam (2005) model.

• Journal of The Korean Society of Clinical Toxicology
• /
• v.9 no.2
• /
• pp.49-55
• /
• 2011

Purpose: Acetanilide has been in widespread use as an amide herbicide compound. However, available data regarding acute human poisoning is scarce. The aim of this study was to analyze the clinical characteristics of acetanilide poisoning in order to identify the risk factors associated with severity. Methods: We conducted a retrospective observational study encompassing the period January 2005 to December 2010, including adult ED patients suffering from acetanilide intoxication. Toxicological history, symptoms observed, clinical signs of toxicity, and laboratory test results were collected for each patient. The patients were classified into two groups for analysis, according their poisoning severity score (PSS). Resulting clinical data and prognostic variables were compared between mild-to-moderate poisoning (PSS 1/2 grades), and severe poisonings and fatalities (PSS 3/4 grades). Results: There were a total of 37 patients, including 26 alachlor, 6 s-metolachlor, 4 mefenacet, and 1 butachlor cases. The majority of patients (81.1%) were assigned PSS 1/2 grades. Changes in mental status and observation of adverse neurologic symptoms were more common in the PSS 3/4 group. The median ingested volume of amide herbicide compound was 250 ml (IQR 200-300 ml) in the PSS 3/4 group, and 80 ml (IQR 50-138 ml) in the PSS 1/2 group. Also, the median GCS observed in the PSS 3/4 group was 13 (IQR 10-14), which was markedly low as compared to a median GCS of 15 in the PSS 1/2 group. Overall mortality rate was 5.4%, and profound cardiogenic shock was observed prior to death in all fatalities. Conclusion: When compared to previous reports, acute acetanilide poisoning resulted in relatively moderate severity. The presence of neurologic manifestations, hypotension, lower GCS score, and larger ingested volumes was associated with more serious effects and mortalities.