Kyu-Seong Cho

Electro-enhanced remediation of radionuclide-contaminated groundwater using zero-valent iron.

Abstract The objective of this study was to develop and evaluate electrochemically‐enhanced immobilization of radionuclides in contaminated groundwater using Fe°. A bench‐scale flow‐through Fe° reactor column with direct current was tested to increase the efficiency and effective life of the Fe° medium by (i) providing an external supply of electrons, (ii) controlling the rate of iron oxidation, and (iii) enhancing the rate of radionuclide immobilization. The removal mechanism appears to be reductive coprecipitation of radionuclides by iron oxidation by creating a reducing environment in the reactive iron barrier. Several factors influence the removal of radionuclides from groundwater using this reactor column including electrode configuration, applied voltage, distance between cathode and anode, and radionuclide concentration.

Electrochemical remediation of trichloroethene-contaminated groundwater using palladized iron oxides.

The objective of this study is to develop electrochemically-enhanced dechlorination of trichloroethene (TCE) using palladized iron oxides minerals for ex situ remediation of contaminated groundwaters. A bench-scale column packed with the palladized iron oxide media connected to a cathode and an anode embedded in a carbon pad was prepared for flow through column tests. Contaminated groundwaters with about 14–16 mg/L TCE were passed from the cathode side to the anode side of the column while the system was supplied with direct current. All of the TCE in the groundwater was dechlorinated even after 300 pore volumes were passed. Furthermore, intermediate reaction products, dichloroethene isomers and vinyl chloride, were not detected in the treated water.

Development and Application of Teaching Aids for Geological Fieldwork Based on Chaeseokgang Area, Buan-gun, Jeonbuk, Korea

This study is to develop teaching aids and materials for geological fieldwork and to maximize their effects in educating high school students in Korea. The site of geological fieldwork, Kyokpo Chaeseokgang area, is located in Byunsan national park in Jeonbuk Province. The sedimentary succession of Chaeseokgang developed in the era of Cretaceous shows large-scale and distinct sedimentary structures on sea cliffs. In this study, teaching aids and materials of earth science for secondary-level students were developed based on the sedimentary structures of Chaeseokgang. A 5-step teaching model of earth science fieldwork was applied to a group of 13 students, who had been involved in clubs related to earth science in a science high school, using teaching aids and materials developed in this study. The teaching aids and fieldwork-related materials were also presented to a group of 37 students, who did not take fieldwork or fieldwork-related classes during the period of the study. The results of this study showed that the use of fieldwork-related aids and materials was effective in helping the students in both groups improve their self-directed teaming and practical understanding of earth science.

Development and Application of Teaching Materials for Geological Fieldwork in Jeokbyeokgang Area, Gyeokpo, Byeonsan, Korea

This study is to develop teaching materials for the geological fieldwork of Jeokbyeokgang area located in the national park of the Byeonsan-bando National Park, Buangun, Jeonbuk, Korea. The developed teaching materials are used in middle school science to effectively teach the fieldwork of the area. The sedimentary succession of Jeokbyeokgang area in the Cretaceous age, Mesozoic, represents the large-scale and distinctive sedimentary structures on sea cliffs, which are worth developing as teaching materials for the earth science fieldwork. The area of Jeokbyeokgang also comprises various geological structures related to the advanced learning programs as well as those within the curriculum of earth science in middle school level. A five-step fieldwork model was applied to 20 students in middle school earth science. This study quantitatively analyzed students` responses to the process of the fieldwork activity. Results indicated that the fieldwork activity using the developed teaching materials was effective in helping the students to improve their self-directed learning and practical understanding of earth science.

Development and Application of Teaching Materials for Geological Fieldwork in the Area of Bongwhabong, Buan-gun, Jeonbuk, Korea

This study is to develop teaching materials for geological fieldwork around Bonghwabong area in the national park of the Byeonsan Peninsula, Buangun, Jeonbuk. The developed materials are applied in the geological fieldwork of science high school students to maximize the effects of use. The sedimentary succession of the Bonghwabong area in the Cretaceous age, Mesozoic, represents large-scale and distinctive sedimentary structures on the sea cliffs, which are utilized as teaching materials for earth science fieldwork. The area of Bonghwabong also comprises various geological structures related to advanced learning programs as well as those within the curriculum of high school earth science. A five-step fieldwork model was applied to 15 students in clubs related to earth science in a science high school. This study used a qualitative methodology to analyze students` responses that were gathered about the process of fieldwork. During the activity, a qualitative analysis was carried out by using discussions and interviews both with the students and the teacher. Results indicated that the fieldwork activity using teaching materials was effective in helping the students improve their self-directed learning and practical understanding of earth science.

A Biogeochemical Study on the Heavy Metal Leaching from Coal Fly Ash Disposed by Dangjin Fire Plant in the Coastal Environment

It is known that coal-derived fly ashes have the unique chemical composition and mineralogical characteristics. Since iron oxides in coal fly ash are enriched with heavy metals, the subsurface media including soils, underground water, and sea water are highly likely contaminated with heavy metals when the heavy metals are leached from fly ashes by water-fly ash interactions. The purpose of this study was to investigate how indigenous bacteria affect heavy metal leaching and mineralogy in fly ash slurry during the fly ash-seawater interactions in the ash pond located in Dangjin seashore, Korea. The average pH of ash pond seawater was 8.97 in nature. Geochemical data showed that microbial activity sharply increased after the 7th day of the 60-day course batch experiments. Compared with other samples including autoclaved and natural samples, was likely to decrease considerably in the fly ash slurry samples when glucose was added to stimulate the microbial activity. Geochemical data including Eh/pH, alkalinity, and major and trace elements showed that the bacteria not only immobilize metals from the ash pond by facilitating the chemical reaction with Mn, Fe, and Zn but may also be able to play an important role in sequestration of carbon dioxide by carbonate mineral precipitation.

The Valuation of Geosites and Geoheritages in the Buan Volcanics of Byeonsanbando National Park

This study aims analyze the geological values in relation to the volcanic area and to investigate a possibility of the geosites and the geoheritages in Byeonsanbando area. The results indicate that the seven geosites are relevant as a potential national geopark, including Gunghang, Solseom Island, and Mohang located in Oebyeonsan and Jikso Falls, Gulbawi, Seongye Falls, and Ulgumbawi located in Naebyeonsan. Solseom Island and Mohang should be preserved and used as a place of the geological study because of their high geological heritage values. Besides, Jeokbyeokgang and Chaeseokgang are famous for excellent natural landscapes as they have been proven with academic values. Like this, these area are considered to have sufficient value as a national geopark of Korea, because their geoheritages are variously distributed in Byeonsanbando area.

Petrological Investigation of the Specimens in School Rock Gardens in Jeonju, Korea

The effective teaching of Earth Science in the classroom should be augmented by field studies of rocks and minerals in a competently designed school rock garden(SRG). The displayed specimens must be correctly identified, labeled and esthetically evaluated. SRG is more than a general garden with just landscaping and it should provide students with freedom of conducting independent inquiries. The composition of the selected specimens should be representative of the bedrocks of region as well as of Korea in general. There are 130 schools in Jeonju-city and 35 (26.9%) have established rock gardens. There is a pressing demand for more gardens and number of display samples in school. The existing displays need improvement because some samples are not correctly identified and labeled. In addition, there is a duplication of rock types as well as lack of important rock types. The number and composition of the displayed rocks and minerals should be related to the school curriculum and reflect representative bedrocks of Jeonju-city and region.

A Perception of Beginning Earth Science Teachers on Porphyritic Texture

This study is to explore the Pedagogical Content Knowledge of beginning earth science teachers about the porphyritic texture of igneous rocks, and to suggest the teaching device that can prevent a trial and error of students in earth science instruction. We developed an interview guideline concerned with basic perception on the porphyritic texture, formation condition and formation process of porphyritic rocks, teaching and learning on porphyritic rocks for it. And data was collected from 5 beginning earth science teachers (3 high schools, 2 middle schools) through a group discussion method. In result, despite the porphyritic texture can be found at hypabyssal rocks as well as volcano rocks and plutonic rocks, most beginning earth science teachers cognized that it could be found at hypabyssal rocks only by focusing the formation depth of hypabyssal rocks. Also, the formation of porphyritic texture should be considered the factors such as cooling rate, nucleation density, growth rate, growth time, etc. However they mainly reflected the formation temperature and growth rate as its parameter. Participants have wrongly perceived that a phenocryst necessarily differs from a groundmass on chemical composition. And they are inclined to discriminate phenocryst from groundmass through their chemical differences, instead of grain size.

The Effects of Astronomical Animation Module on Earth Science Gifted Students's Conceptual Change of Diurnal Motion

The purpose of this study is to investigate the effects of astronomical animation module on students` conceptual change regarding the concepts of diurnal motion of stars. Four students participated in this study, who never learned about the diurnal motion of stars. An animation module was developed by using Flash MX to readily understand the concept of space. In addition, we inserted a teacher`s voice with supplementary materials into the animation module to help students learn individually. The animation module was comprised of the movement of the Earth, the Moon and the planet. The earth science gifted students` preconception on diurnal motion of stars was analyzed with pre-test using questionnaires and interviews. After the instruction with animation module, the effect of conceptual change was examined by comparing pre and post-test. The results indicated that three students correctly presented about the motion of the star by all directions in middle latitude. Four students showed their understanding that stars travelled straight in all directions. Finally, all of four students whose preconceptions were that the star rotated perpendicularly showed the conceptual change of diurnal motion that the star traveled diagonally.