• Journal of The Korean Association For Science Education
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• v.41 no.3
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• pp.183-192
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• 2021

As part of the second-year monitoring study on the implementation of the 2015 revised science curriculum, this study investigated high school science teachers' perception and realization of instruction and assessment of elective courses to derive measures to settle and improve the science curriculum. A total of 244 high school science teachers responded to the survey questionnaire, and 9 teachers participated in interviews. In survey results, science teachers are contemplating ways to increase students' science competencies and their participation in classes, but still, lecture-oriented classes are most often used in their teaching. Regarding assessment, teachers responded that there were positive changes in all of the questions related to process-based assessment (PBA). Regarding the difficulty of managing science elective courses, teachers most often selected increased numbers of subjects being covered, overload of work, and the burden of restructuring classes considering various ways of teaching and assessment. Through in-depth interviews, teachers argued the difficulty for Science I courses to emphasize student participatory classes compared to integrated science, and the difficulty to implement student participatory classes for Science II courses, which are mainly placed in the third grade. Teachers also argue that it is necessary to secure time to implement PBA in science elective courses, and that there is no need to implement PBA for the science experiment since there are no tests on the SAT. Based on the results of the study, discussed in the conclusion are support plans for the settlement of PBA in elective courses, and the need for in-depth analysis of the direction and cause of student participatory classes and PBA at the school.

• Journal of agricultural medicine and community health
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• v.18 no.2
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• pp.131-140
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• 1993

This study was conducted to examine the levels of mercury in tissue of Carassius carassius collected at five areas(Andong, Sangju, Waekwan, Gangjung and Gaejin) in Nakdong river from February to March, 1993. The contents of total and organic mercury were determined by methods of Gold amalgam and Selective atomic absorption with mercury analyzer(Model SP-3A). The total mercury contents in muscle were $0.148{\pm}0.0646$ ppm by the Gold amalgam, and $0.113{\pm}0.0345$ ppm by the Selective atomic absorption, but in all parts of Carassius carassius were $0.342{\pm}0.4235$ ppm and $0.240{\pm}0.2974$ ppm respectively. These two methods were extremely high correlated(r=0.9812, p<0.001). The mean value of total and organic mercury by the two methods was high in the order of bone>fin>muscle, respectively, and the proportion of organic mercury to the total was 69.0%. Mean value of total and organic mercury in the muscle was the highest at Wakeman located in middle basin of Nakdong river, and in the bone and fin was the highest at Andong dam located in upper basin. According to sizes and parts of fish, the concentration of mercury was the highest in the muscle of 15-19 cm group, the highest in the bone of 10-14 cm group and in the fin of 20-24 cm group.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.20-27
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• 1983

A series of laboratory experiment was conducted to find out the chemical composition, characterization of humic substances by physical and chemical methods and reaction of Na-pyrophosphate, $Ca(OH)_2$ and rice straw with albumin on the degradation of soil organic matter in the volcanic ask soils of the Jeju Island. Results obtained were summarized as follows: 1. The contents of organic matter, available silicon, active iron and aluminum concentration in volcanic ash the soils were remarkably higher but available phosphorous was comparatively lower than the mineral soils. In volcanic ash soil, the contents of potassium, calcium and magnessium were higher in upland soil than that of forest soil. The ratios of active $Al^{{+}{+}{+}}/Fe^{{+}{+}}$, C/P and $K/Ca^+$ Mg were apparently high in volcanic ash soils while that of $SiO_2$/O.M. was high in mineral soil. 2. The carbon/nitrogen ratio in humin, humic acid content in organic matter, and carbon contents of humin in total carbon of soil organic matter were apparently higher in the volcanic ash soils than in the mineral soils, The total nitrogen and fractions of acid or alkali soluble nitrogen were remarkably high in volcanic ash soils while mineralizable nitrogen ($NH_4$-N and $NO_3$) contents were high in mineral soils. 3. The values of K600, RF and log K were also higher in volcanic ash soils than those in mineral soils, and the absorbance in the visible range were high and color was dark in the soil of which humification was progressed Extracted humic acid from volcanic ash soil was less reactive to the oxidizing chemical reagent and was persistance to the acid or alkali hydrolysises. 4. The major oxygen-containing functional groups in humic substances of volcanic ash soils were phenolic-OH alcoholic-OH and carboxyl groups while those in mineral soil were methoxyl and carbonyl groups. 5. Absorption spectra of alkaline solution of humic acid ranged from 200 nm to maxima 500 nm. Visible spectra peaks of from humic substances in the visible region were recognized at 350, 420, 450 and 480 nm. Only one single absorbance peak was observed in the visible region at 362 nm for Heugag series and two absorbance Peak were also at 360 nm and 390 nm for Yeungrag series. 6. Evolution of carbon as $Co_2$ was increased with addition of Na-pyrophosphate in Namweon and Heugag series, and "priming effects" took place on the soil organic matter decomposition by addition of rice straw with albumin in Ido series.