• Journal of the Korean Society of Groundwater Environment
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• v.7 no.3
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• pp.103-115
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• 2000

The formation of brown-colored precipitates is one of the serious problems frequently encountered in the development and supply of groundwater in Korea, because by it the water exceeds the drinking water standard in terms of color. taste. turbidity and dissolved iron concentration and of often results in scaling problem within the water supplying system. In groundwaters from the Pajoo area, brown precipitates are typically formed in a few hours after pumping-out. In this paper we examine the process of the brown precipitates' formation using the equilibrium thermodynamic and kinetic approaches, in order to understand the origin and geochemical pathway of the generation of turbidity in groundwater. The results of this study are used to suggest not only the proper pumping technique to minimize the formation of precipitates but also the optimal design of water treatment methods to improve the water quality. The bed-rock groundwater in the Pajoo area belongs to the Ca-$HCO_3$type that was evolved through water/rock (gneiss) interaction. Based on SEM-EDS and XRD analyses, the precipitates are identified as an amorphous, Fe-bearing oxides or hydroxides. By the use of multi-step filtration with pore sizes of 6, 4, 1, 0.45 and 0.2 $\mu\textrm{m}$, the precipitates mostly fall in the colloidal size (1 to 0.45 $\mu\textrm{m}$) but are concentrated (about 81%) in the range of 1 to 6 $\mu\textrm{m}$in teams of mass (weight) distribution. Large amounts of dissolved iron were possibly originated from dissolution of clinochlore in cataclasite which contains high amounts of Fe (up to 3 wt.%). The calculation of saturation index (using a computer code PHREEQC), as well as the examination of pH-Eh stability relations, also indicate that the final precipitates are Fe-oxy-hydroxide that is formed by the change of water chemistry (mainly, oxidation) due to the exposure to oxygen during the pumping-out of Fe(II)-bearing, reduced groundwater. After pumping-out, the groundwater shows the progressive decreases of pH, DO and alkalinity with elapsed time. However, turbidity increases and then decreases with time. The decrease of dissolved Fe concentration as a function of elapsed time after pumping-out is expressed as a regression equation Fe(II)=10.l exp(-0.0009t). The oxidation reaction due to the influx of free oxygen during the pumping and storage of groundwater results in the formation of brown precipitates, which is dependent on time, $Po_2$and pH. In order to obtain drinkable water quality, therefore, the precipitates should be removed by filtering after the stepwise storage and aeration in tanks with sufficient volume for sufficient time. Particle size distribution data also suggest that step-wise filtration would be cost-effective. To minimize the scaling within wells, the continued (if possible) pumping within the optimum pumping rate is recommended because this technique will be most effective for minimizing the mixing between deep Fe(II)-rich water and shallow $O_2$-rich water. The simultaneous pumping of shallow $O_2$-rich water in different wells is also recommended.

• The Journal of Engineering Geology
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• v.26 no.1
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• pp.117-128
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• 2016

Chemical reaction tests were performed to assess the properties of hardened specimens of cement pastes (KS-1 Portland and Class G) exposed to supercritical CO₂ for 1, 10, and 100 days. After exposure, the samples' measured permeability and strength were compared with values measured for pristine samples. The pristine cements had permeabilities of 0.009~0.025 mD, which increased by one order of magnitude after 100 days of exposure (to 0.11~0.29 mD). The enhancement of permeability is attributed to the stress release experienced by the samples after removal from the pressure vessel after exposure. Despite its enhancement, the measured permeability mostly remained lower than the API (American Petroleum Institute) recommended maximum value of 0.2 mD. The degradation of the cement samples due to exposure to supercritical CO₂ led to a layer of altered material advancing inwards from the sample edges. The Vickers hardness in the altered zone was much higher than that in the unaltered zone, possibly owing to the increase in density and the decrease in porosity due to the carbonation that occurred in the altered zone. Hardness close to the edge within the altered zone was found to have decreased significantly, which is attributed to the conversion of C-S-H into less-strong amorphous silica.

• Journal of Korean Library and Information Science Society
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• v.30 no.2
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• pp.123-153
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• 1999

This article aims at finding the ways, on the basis of the studies about the behaviors to search the existing CD-ROM databases, so that the searchers who retrieve the on-line MEDLINE used in the medical libraries can use the data more efficiently than now. We gave the questionnaires to the librarians in 60 medical libraries and searched the literatures and realities on the behaviors of the data uses to examine the search behaviors of the MEDLINE in the medical libraries. The result is as follows: 1) The medical data system rate for single users was $53\%$ and the ons for multi users $43\%$. As for the time which users retrieve for a week, under two hours was $75\%$, between 3 and 8 hours $18.3\%$, and eve. 9 hours $6.7\%$. 2) The increasing factors of the search result are (1) an enough discussion and interview between librarians and users, and (2) the use of the correct indexing terms, Thesaurus, and Keyword. In principle users must search directly. However, the librarians searched instead in case that the retrieval result was under two hours a week$(75\%)$. 3) As for the search fee, $91\%$ was free and $9\%$ was charged. Also search effectiveness was enhanced by the means of Inter-Library Loan Service & Information Network. 4) The medical librarians answered the questionnaire that they need the application education of professional knowledge, medical terms(thesaurus) and electronic medium, and also they need the computer education, interview technique and reeducation to give a satisfactory service. 5) As for the satisfactory degree of MEDLINE application, they answered $44.6\%$ for economy, $38.2\%$ for the conveniency of the time required, and $58.9\%$ for the users' search satisfaction answered respectively. 6) The application of MEDLINE system enhanced the medical libraries' image and had an effect on the users' satisfaction of using the data and search, the data activities and the research achievement. 7) In the past MeSH was used but as the time passes CD-ROM MEDLINE search behavior was preferred to On-line one.

• Journal of Korean Library and Information Science Society
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• v.42 no.3
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• pp.189-208
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• 2011

In the digital environment where the Internet and IT change rapidly, researchers have utilized scientific information by relying on more complex and various media than before. This study performed a group interview with thirteen questions derived from five categories in order to understand information needs and information seeking behaviors of Korean doctoral researchers in this information environment. The five categories are (1) identifying information resource usage pattern, (2) attitude towards information resources and reasons for use, (3) IT skills and information literacy, (4) physical library use vs electronic access, and (5) attitudes toward the digital library. In particular, this study focused on analyzing similarities and differences of two groups of researchers selected equally in the humanities and social sciences and in science and technology by doing the interview. The research showed that there are no differences in the goal of using scientific information, information literacy, the ratio of using written materials to electronic resources, and routes of acquiring research ideas or knowledge, but there are differences in materials used for studies or researches and in favorite scientific portal sites.

• Journal of Korean Library and Information Science Society
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• v.52 no.2
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• pp.401-428
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• 2021

Recently, libraries are trying to communicate with users using various social media. Among them, Instagram is the most used SNS by users recently. Therefore, in this study, in order to effectively operate the library Instagram, we looked at how Instagram in the library is operated, what posts and contents people are interested in, and how the library can utilize it. By analyzing the Instagram operation status of Instagram, we tried to suggest improvement plans and activation plans. For this purpose, theoretical background research on SNS and Instagram, analysis of prior research, and related data were collected and analyzed. Next, for 82 domestic library accounts opened on Instagram, the library type, region, and Instagram account number of posts, 'followers', 'follows', images, etc. were collected, and the Text, hashtags, upload date, number of 'likes' and comments were analyzed. As a result of the study, it was found that increasing followers, uploading user-customized posts, formalizing account profiles, using library-specific hashtags, and communication with users are necessary to activate library Instagram.

• Journal of Korean Library and Information Science Society
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• v.53 no.2
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• pp.189-214
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• 2022

The purpose of this study is to provide an understanding of the current status of picture book-related research in Korea. For this purpose, 1,660 picture book-related research papers produced in Korea by 2021 were analyzed. The results revealed through the analysis are summarized as follows. First, research papers began to appear in the mid-1990s and began to increase significantly around 2010. Second, the journal with the most research papers was 『Journal of Children's Literature and Education』, accounting for 17.7% of the total. Third, the representative researchers who led the production of the papers are Eun-Ja Hyun and Hea-Sook Jo. Fourth, by research type, individual research papers accounted for 39% and joint research 61%. Fifth, as a result of the analysis of the research topic, the study of the contents (analysis) of picture books (33.4%), the study of the effect of picture books (29.6%), and the study of perception, reaction, and experience of picture books (18.0%) were in order. Sixth, as a result of the research method analysis, experimental studies (35.7%), content analysis (33.7%), literature studies (13.3%), and qualitative studies (9.3%) were in order. Based on the results of the analysis, the researcher suggested diversifying the research production route, expanding the trend of collaboration between universities and the field, diversifying research topics, and enhancing the validity and diversity of research methods.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.2-31
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• 2020

CheomSeongDae (瞻星臺) is a stone structure built in Gyeongju, the former Silla Dynasty capital, during the reign of Queen Seondeok (632~647AD). There exist dozens of hypotheses regarding its original purpose. Depending on to whom you ask, the answer could be a celestial observatory, a religious altar, a Buddhist stupa, a monumental tower symbolizing scientific knowledge, and so on. The most common perception of the structure among lay people is a stargazing tower. Historians, however, have suggested that it was intended as "a gateway to the heavens", specifically the Trāyastriṃśa or the second of the six heavens of Kāmadhātu located on the top of Mountain Sumeru. The name "Cheom-seong-dae" could be interpreted in many different ways. 'Cheom (瞻)' could refer to looking up, staring, or admiring, etc.; 'Seong (星)' could mean a star, heaven, night, etc.; and 'heaven' in that context can be a physical or religious reference. 'Dae (臺)' usually refers to a high platform on which people stand or things are placed. Researchers from the science fields often read 'cheom-seong' as 'looking at stars'; while historians read it as 'admiring the Trāyastriṃśa' or 'adoring Śakra'. Śakra is said to be the ruler of Trāyastriṃśa' who governs the Four Heavenly Kings in the Cāturmahārājika heaven, the first of the six heavens of Kāmadhātu. Śakra is the highest authority of the heavenly kings in direct contact with humankind. This paper examined the usages of 'cheom-seong' in Chinese literature dated prior to the publication of 『Samguk Yusa』, a late 13th century Korean Buddhist historical book that contains the oldest record of the structure among all extant historical texts. I found the oldest usage of cheom-seong (瞻星臺) in 『Ekottara Āgama』, a Buddhist script translated into Chinese in the late 4th century, and was surprised to learn that its meaning was 'looking up at the brightness left by Śakra'. I also found that 'cheom-seong' had been incorporated in various religious contexts, such as Hinduism, Confucianism, Buddhist, Christianism, and Taoism. In Buddhism, there was good, bad, and neutral cheom-seong. Good cheom-seong meant to look up to heaven in the practice of asceticism, reading the heavenly god's intentions, and achieving the mindfulness of Buddhism. Bad cheom-seong included all astrological fortunetelling activities performed outside the boundaries of Buddhism. Neutral cheom-seong is secular. It may help people to understand the nature of the physical world, but was considered to have little meaning unless relating to the spiritual world of Buddhism. Cheom-seong had been performed repetitively in the processes of constructing Buddhist temples in China. According to Buddhist scripts, Queen Māyā of Sakya, the birth mother of Gautama Buddha, died seven days after the birth of Buddha, and was reborn in the Trāyastriṃśa heaven. Buddha, before reaching nirvana, ascended from Jetavana to Trāyastriṃśa and spent three months together with his mother. Gautama Buddha then returned to the human world, stepping upon the stairs built by Viśvakarman, the deity of the creative power in Trāyastriṃśa. In later years, King Asoka built a stupa at the site where Buddha descended. Since then, people have believed that the stairway to the heavens appears at a Buddhist stupa. Carefully examining the paragraphic structure of 『Samguk Yusa』's records on Cheomseongdae, plus other historical records, the fact that the alignment between the tomb of Queen Seondeok and Cheomseongdae perfectly matches the sunrise direction at the winter solstice supports this paper's position that Chemseongdae, built in the early years of Queen SeonDeok's reign (632~647AD), was a gateway to the Trāyastriṃśa heaven, just like the stupa at the Daci Temple (慈恩寺) in China built in 654. The meaning of 'Cheom-seong-dae' thus turns out to be 'adoring Trāyastriṃśa stupa', not 'stargazing platform'.

• The Journal of Engineering Geology
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• v.25 no.4
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• pp.533-545
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• 2015

Spatial and seasonal variations in hydrogeochemical characteristics and the factors affecting the deterioration in quality of shallow portable groundwater in an agricultural area are examined. The aquifer consists of (from the surface to depth) agricultural soil, weathered soil, weathered rock, and bedrock. The geochemical signatures of the shallow groundwater are mostly affected by the NO₃⁻ and Cl⁻ contaminants that show a gradual downward increase in concentration from the upper area, due to the irregular distribution of contamination sources. The concentrations of the major cations do not varied with the elapsed time and the NO₃⁻ and Cl⁻ ions, when compared with concentrations in background groundwater, increase gradually with the distance from the upper area. This result suggests that the water quality in shallow groundwater deteriorates due to contaminant sources at the surface. The contaminations of the major contaminants in groundwater show a positive linear relationship with electrical conductivity, indicating the deterioration in water quality is related to the effects of the contaminants. The relationships between contaminant concentrations, as inferred from the ternary plots, show the contaminant concentrations in organic fertilizer are positively related to concentrations of NO₃⁻, Cl⁻, and SO₄²⁻ ions in the shallow portable groundwaters, which means the fertilizer is the main contaminant source. The results also show that the deterioration in shallow groundwater quality is caused mainly by NO₃⁻ and Cl⁻ derived from organic fertilizer with additional SO₄²⁻ contaminant from livestock wastes. Even though the concentrations of the contaminants within the shallow groundwaters and the contaminant sources are largely variable, it is useful to consider the ratio of contaminant concentrations and the relationship between contaminants in groundwater samples and in the contaminant source when analyzing deterioration in water quality.

• Journal of Environmental Impact Assessment
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• v.30 no.1
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• pp.35-48
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• 2021

In this study, the assessment of field applicability of in-situ remediation of nitrate-contaminated groundwater located in Yesan-gun was performed. Zero-valent iron/bio composite media injected PRB (Permeable Reactive Barrier) and monitoring well were installed in the contaminated groundwater site and monitored main remediation indicators during the PRB operation. Nitrate, nitrite, ammonia, Fe ion, TOC, and turbidity were analyzed and the diversity and population of microorganism in the PRB installed site were investigated for the verification of effect of injected PRB. In the study site where is an agricultural area, a river flows from west to east that forms a river boundary and the southern area has an impermeable sector. It was found that nitrate flows into the river, which is similar as groundwater flow. Simulation result for the fate of nitrate in groundwater showed steady state of nitrate arrived after 3~5 years passed. However, it is just to consider current conditions with no additional input of contaminant source, if additional input of contaminant source occurs contamination dispersion and time for steady state are expected to be increased. The monitoring results showed that Fe ion, TOC and turbidity in groundwater were not clearly changed in concentration after PRB installation, which indicates adaptability of the injected PRB for remediation of groundwater with no additional harmful effect to water quality. The concentration of nitrate maintained less than 5mg/L until 42 days after PRB installation and recovered its initial concentration after 84 days passed and showed termination of reactivity of injected zero-valent iron/bio composite media for removal nitrate. Nitrite and ammonia ions found after installation of PRB indicates reductive removal of nitrate. And the outstanding increase of microorganism diversity and population of Betaproteobacteria Class which includes denitrification microorganism explains biologically reductive removal of nitrate in injected PRB.