• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.35-43
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• 2023

The fine particulate structure of biochar limits its use as a heavy metal adsorbent, and makes separation of the biochar from the solution technically challenging, thereby reducing recovery of the heavy metals. To address this issue, this study prepared biochar beads under various mixing conditions and investigated their efficiency in removing Pb from aqueous solutions using adsorption models. The biochar beads were produced by mixing alginate and biochar at different ratios: alginate bead (AB), 1% biochar + bead (1-BB), 2.5% biochar + bead (2.5-BB), and 5% biochar + bead (5-BB). The results revealed that the Freundlich isothermal adsorption pattern of the biochar beads to Pb was of the L-type. The highest Langmuir isothermal adsorption capacity (28.736 mg/g) was observed in the 2.5-BB treatment. The dominant mechanism among the kinetic adsorption characteristics of biochar beads for Pb was chemical adsorption. Additionally, the optimal pH range for Pb adsorption was found to be between 4 and 5.5. The highest Pb removal efficiency (97.9%) was achieved when 26.6 g/L of biochar beads were used. These findings suggest that biochar beads are an economical and highly efficient adsorbent that enables separation and recovery of fine biochar particles.

• Economic and Environmental Geology
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• v.55 no.6
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• pp.727-736
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• 2022

Ice wedges are subsurface ice mass structures that formed mainly by freezing precipitation with airborne dust and surrounding soil particles flowed through the active layer into the cracks growing by repeating thermal contractions in the deeper permafrost layer over time. These ice masses characteristically contain high concentrations of solutes and solids. Because of their unique properties and distribution, the possibility of harnessing ice wedges as an alternative archive for reconstructing paleoclimate and paleoenvironment has been recently suggested despite limited studies. It is imperative to preserve the physicochemical properties of the ice wedge (e.g., solute concentration, mineral particles) without any potential alteration to use it as a proxy for reconstructing the paleo-information. Thawing the ice wedge samples is prerequisite for the assessment of their physicochemical properties, during which the paleo-information could be unintentionally altered by any methodological artifact. This study examined the effect of thawing conditions and procedures on the physicochemical properties of solutes and solid particles in ice wedge samples collected from Cyuie, East Siberia. Four different thawing conditions with varying temperatures (4 and 23℃) and oxygen exposures (oxic and anoxic) for the ice wedge sample treatment were examined. Ice wedge samples thawed at 4℃ under anoxic conditions, wherein biological activity and oxidation were kept to a minimum, were set as the standard thawing conditions to which the effects of temperature and oxygen were compared. The results indicate that temperature and oxygen exposure have negligible effects on the physicochemical characteristics of the solid particles. However, the chemical features of the solution (e.g., pH, electric conductivity, alkalinity, and concentration of major cations and trace elements) at 4℃ under oxic conditions were considerably altered, compared to those measured under the standard thawing conditions. This study shows that the thawing condition of ice wedge samples can affect their chemical features and thereby the geochemical information therein for the reconstruction of the paleoclimate and/or paleoenvironment.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.676-683
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• 2022

Due to the effects of rapid changes in the living environment since 2000 and the recent unforeseen pandemic, people are refraining from domestic and international traveling and movement, and outdoor activities for health and the public value of forest trails, called Dullegil Trail in Korea, have become more important. This study estimated the environmental value of the tentatively named "East-West Trail," which connects the forest trails crossing Chungcheong and Gyeongsang Provinces using CVM (Contingent Valuation Method). It surveyed visitors to the East-West Trail, and 725 questionnaires were used for analysis. The average characteristics of respondents were those who exercised 2-3 times per week, visited a forest trail not far from their residence with friends or family, and showed a tendency to spend 50 thousand Korean won or more per visit. Visitors to the Dullegil Trail felt that there was a shortage of information boards on the forest trail, and they preferred a shelter in appropriate locations. We used a double-bounded dichotomous choice (BDDC) logit model proposed by Hanemann to measure the conservation value of the East-West Trail. It was estimated that the environmental value that a visitor to the East-West Trail could obtain was 30,087 won per trip. The estimated environmental value of the East-West Trail can be converted to about 94 billion won total visitors annually based on the population belonging to the direct-use zone near the East-West Trail. As there has been no study on the environmental value of forest trails using CVM, the results of this study will be able to suggest the feasibility of the government policies on forest trails.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.526-535
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• 2021

Spatial sampling design plays an important role in GIS-based modeling studies because it increases modeling efficiency while reducing the cost of sampling. In the field of agricultural systems, research demand for high-resolution spatial databased modeling to predict and evaluate climate change impacts is growing rapidly. Accordingly, the need and importance of spatial sampling design are increasing. The purpose of this study was to design spatial sampling of paddy fields (11,386 grids with 1 km spatial resolution) in Korea for use in agricultural spatial modeling. A stratified random sampling design was developed and applied in 2030s, 2050s, and 2080s under two RCP scenarios of 4.5 and 8.5. Twenty-five weather and four soil characteristics were used as stratification variables. Stratification and sample allocation were optimized to ensure minimum sample size under given precision constraints for 16 target variables such as crop yield, greenhouse gas emission, and pest distribution. Precision and accuracy of the sampling were evaluated through sampling simulations based on coefficient of variation (CV) and relative bias, respectively. As a result, the paddy field could be optimized in the range of 5 to 21 strata and 46 to 69 samples. Evaluation results showed that target variables were within precision constraints (CV<0.05 except for crop yield) with low bias values (below 3%). These results can contribute to reducing sampling cost and computation time while having high predictive power. It is expected to be widely used as a representative sample grid in various agriculture spatial modeling studies.

• Journal of the Korea Society of Computer and Information
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• v.14 no.12
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• pp.157-167
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• 2009

Recently, the leakage of confidential information and personal information is taking place on the Internet more frequently than ever before. Most of such online security incidents are caused by attacks on vulnerabilities in web applications developed carelessly. It is impossible to detect an attack on a web application with existing firewalls and intrusion detection systems. Besides, the signature-based detection has a limited capability in detecting new threats. Therefore, many researches concerning the method to detect attacks on web applications are employing anomaly-based detection methods that use the web traffic analysis. Much research about anomaly-based detection through the normal web traffic analysis focus on three problems - the method to accurately analyze given web traffic, system performance needed for inspecting application payload of the packet required to detect attack on application layer and the maintenance and costs of lots of network security devices newly installed. The UTM(Unified Threat Management) system, a suggested solution for the problem, had a goal of resolving all of security problems at a time, but is not being widely used due to its low efficiency and high costs. Besides, the web filter that performs one of the functions of the UTM system, can not adequately detect a variety of recent sophisticated attacks on web applications. In order to resolve such problems, studies are being carried out on the web application firewall to introduce a new network security system. As such studies focus on speeding up packet processing by depending on high-priced hardware, the costs to deploy a web application firewall are rising. In addition, the current anomaly-based detection technologies that do not take into account the characteristics of the web application is causing lots of false positives and false negatives. In order to reduce false positives and false negatives, this study suggested a realtime anomaly detection method based on the analysis of the length of parameter value contained in the web client's request. In addition, it designed and suggested a WAF(Web Application Firewall) that can be applied to a low-priced system or legacy system to process application data without the help of an exclusive hardware. Furthermore, it suggested a method to resolve sluggish performance attributed to copying packets into application area for application data processing, Consequently, this study provide to deploy an effective web application firewall at a low cost at the moment when the deployment of an additional security system was considered burdened due to lots of network security systems currently used.

• Korean Journal of Heritage: History & Science
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• v.56 no.2
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• pp.80-98
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• 2023

In the late Joseon Dynasty, when the bride would ride a palanquin when she went to live with her in-laws, it was a custom to cover the palanquin with tiger skin to ward off misfortunes that may come her way. The higher classes used tiger skin or leopard skin for this purpose, but the common people had to substitute this expensive item with a tiger pattern painted on a blanket. Such blankets were called hotanja, hogu, hoguyok and the like. The term "hotanja" is a pure Korean word. It is not known when the cover for the bridal palanquin was first used, but it was popular from the end of the 19^th century and then gradually disappeared. This is due to the introduction of new Western style weddings that eliminated the need for a bridal palanquin. The tiger print blanket was used not only to cover the bride's palanquin but also to cover a table or floor during the wedding ceremony. This study ran a material analysis on nine pieces of tiger print blankets. All of the blanket artifacts examined in this study had an outer cover and a lining made of fabric that used cotton thread for the warp and wool thread for the weft. Two kinds of wool were found in the weft thread in the outer covers: fat-tailed sheep hair from China and goat hair for carpets from the Hebei province, China. Records show that "blankets with painted tiger patterns" were imported from Russia, and the imported blankets were from Russia and China. The outer cover can be categorized into six types, and the lining into three types depending on the weave and direction of the thread twist. The hem facing can be divided into four types. The lining and outer cover use the full width of the fabric, which was woven in wide widths of 135 cm or wider. The tiger pattern on the blanket was made by stenciling. The stencil design of the body and tail of the tiger were placed on a red blanket to be painted in white, and then the background color of the tiger, which is yellow, would be painted over the white, and then black stripes would be added. The pattern of the tiger varies, which shows that the blankets were made by various craftspeople. The pattern of the tiger print blanket is usually of a tiger lying down, but there were tiger print blankets with a tiger standing up. The pattern of the tiger grew smaller over time, and flower patterns were added in the background. Decorative elements were gradually added to the tiger print blanket patterns, but its function as a palanquin cover became lost. By taking the features of tiger print blankets into consideration, it can be assumed that there are imported pieces among the remaining pieces, and were produced in various places because it was popular at that time.

• Korean Journal of Heritage: History & Science
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• v.56 no.2
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• pp.136-146
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• 2023

Biological materials, such as stuffed specimens, can release various acids or volatiles. There has been no research carried out on the emission characteristics of organic compounds generated from the preservatives used in taxidermy specimens or associated manufacturing materials and methods. Therefore, in order to identify the organic compounds generated from taxidermy specimens, a degradation experiment was conducted on specimens for each material and for storage specimens. To produce Ogye chicken specimens, naphthalene and borax were used as preservatives, and planer sawdust, newspaper, and polystyrene foam were used as the core body materials. The deterioration experiment was conducted for 2 weeks in a high-temperature environment(50℃) and a high-humidity environment (95%), with an Ogye chicken specimen (year 2015) kept in an animal storage facility. Results indicated that the concentration of organic compounds generated by the specimen in the high-temperature environment tended to be greater than that in the high-humidity environment. The preservatives benzene, toluene, xylene, and p-dichlorobenzene were detected in the specimens using naphthalene, confirming that naphthalene is a major organic compound release factor, and the specimens that used sawdust, newspaper, and polystyrene foam also exhibited organic compounds. This appears to have been due to degradation of the material. In addition, ammonia was detected in the specimens for each material due to decay. In particular, the specimens using borax at high temperature were subject to approximately 9 times higher rates of ammonia-related deterioration than the specimens using naphthalene. These results can be considered to result from the prevention of biological damage through insecticidal effects by accelerating the sublimation of naphthalene in a high-temperature environment. Naphthalene is a potentially carcinogenic substance, and when used as a preservative, proper use management is required. Taxidermy specimens can release various organic compounds depending on the manufacturing techniques used, so a systematic preservation management plan is required that depends on conditions such as the applicable manufacturing materials and preservatives.

• Korean Journal of Heritage: History & Science
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• v.56 no.2
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• pp.172-203
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• 2023

<Cheongdamdo>(true-view landscape painting) was identified in this study to be a folding screen painting painted by Jeong Seon(a.k.a. Gyeomjae, 1676~1759) in the 32nd year of King Yeongjo(1756) while exploring the Cheongdam area located in Mt. Bukhansan near Seoul. Cheongdam Byeol-eop(Korean villa), consisting of Waunru Pavilion and Nongwolru Pavilion, was a cultural and artistic base at that time, where Nakron(Confucian political party) education took place and the Baegak Poetry Society met. <Cheongdamdo> is a painting that recalls a period of autumn rainfall in 1756 when Jeong Seon arrived in the Cheongdam valley with his disciple Kim Hee-sung(a.k.a. Bulyeomjae, 1723~1769) and met Hong Sang-han(1701~1769). It focuses on the valley flowing from Insubong peak to the village entrance. The title has a dual meaning, emphasizing "Cheongdam", a landscape feature that originated from the name of the area, while also referring to the whole scenery of the Cheongdam area. The technique of drastically brushing down(刷擦) wet pimajoon(hanging linen), the expression of soft horizontal points(米點), and the use of fine brush strokes reveal Jeong Seon's mature age. In particular, considering the contrast between the rock peak and the earthy mountain and symmetry of the numbers, the attempt to harmonize yin and yang sees it regarded as a unique Jingyeong painting(眞境術) that Jeong Seon, who was proficient in 『The Book of Changes』, presented at the final stage of his excursion. 「Cheongdamdongbugi」(Personal Anthology) of Eo Yu-bong(1673~1744) was referenced when Jeong Seon sought to understand and express the true scenery of Cheongdam and the physical properties of the main landscape features in the villa garden. The characteristics of this garden, which Jeong Seon clearly differentiated from the field, suppressed the view of water with transformed and exaggerated rocks(水口막이), elaborately creating a rain forest to cover the villa(裨補林), and adding new elements to help other landscape objects function. In addition, two trees were tilted to effectively close the garden like a gate, and an artificial mountain belt(造山帶), the boundary between the outer garden and the inner garden, was built solidly like a long fence connecting an interior azure dragon(內靑龍) and interior white tiger(內白虎). This is the Bibo-Yeomseung painting(裨補厭勝術) that Jeong Seon used to turn the poor location of the Cheongdam Byeol-eop into an auspicious site(明堂). It is interpreted as being devised to be a pungsu(feng shui) trick, and considered an iconographic embodiment of ideal traditional landscape architecture that was difficult to achieve in reality but which was possible through painting.

• Journal of Christian Education in Korea
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• v.74
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• pp.107-134
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• 2023

The purpose of this study is to provide a foundation for establishing the correct direction of education that utilizes artificial intelligence, a key technology of the Fourth Industrial Revolution, in the context of Christian education. To achieve this, theoretical and literature research was conducted. First, the research analyzed the historical development of artificial intelligence to understand its characteristics. Second, the research analyzed the use of artificial intelligence in convergence education from an educational perspective and examined the current policy direction in South Korea. Through this analysis, the research examined the direction of Christian education in the era of artificial intelligence. In particular, the research critically examined the perspectives of continuity and change in the context of Christian education in the era of artificial intelligence. The research reflected upon the fundamental educational purposes of Christian education that should remain unchanged despite the changing times. Furthermore, the research deliberated on the educational curriculum and teaching methods that should adapt to the changing dynamics of the era. In conclusion, this research emphasizes that even in the era of artificial intelligence, the fundamental objectives of Christian education should not be compromised. The utilization of artificial intelligence in education should serve as a tool that fulfills the mission permitted by God. Therefore, Christian education should remain centered around God, rooted in the principles of the Bible. Moreover, Christian education should aim to foster creative and convergent Christian nurturing. To achieve this, it is crucial to provide learners with an educational environment that actively utilizes AI-based hybrid learning environments and metaverse educational platforms, combining online and offline learning spaces. Moreover, to enhance learners' engagement and effectiveness in education, it is essential to actively utilize AI-based edutech that reflects the aforementioned educational environments. Lastly, in order to cultivate Christian learners with dynamic knowledge, it is crucial to employ a variety of teaching and learning methods grounded in constructivist theories, which emphasize active learner participation, collaboration, inquiry, and reflection. These approaches seek to align knowledge with life experiences, promoting a holistic convergence of faith and learning.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.4
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• pp.261-283
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• 2023

This study aimed to review the performance stability of PET (Polyethylene terephthalate) fiber reinforcing materials among the synthetic fiber types for which the application of performance reinforcing materials to fiber-reinforced concrete is being reviewed by examining short-term and long-term performance changes. To this end, the residual performance was analyzed after exposing the PET fiber to an acid/alkali environment, and the flexural strength and equivalent flexural strength of the PET fiber-reinforced concrete mixture by age were analyzed, and the surface of the PET fiber collected from the concrete specimen was examined using a scanning microscope (SEM). The changes in were analyzed. As a result of the acid/alkali environment exposure test of PET fiber, the strength retention rate was 83.4~96.4% in acidic environment and 42.4~97.9% in alkaline environment. It was confirmed that the strength retention rate of the fiber itself significantly decreased when exposed to high-temperature strong alkali conditions, and the strength retention rate increased in the finished yarn coated with epoxy. In the test results of the flexural strength and equivalent flexural strength of the PET fiber-reinforced concrete mixture, no reduction in flexural strength was found, and the equivalent flexural strength result also did not show any degradation in performance as a fiber reinforcement. Even in the SEM analysis results, no surface damage or cross-sectional change of the PET reinforcing fibers was observed. These results mean that no damage or cross-section reduction of PET reinforcing fibers occurs in cement concrete environments even when fiber-reinforced concrete is exposed to high temperatures in the early stage or depending on age, and the strength of PET fibers decreases in cement concrete environments. The impact is judged to be of no concern. As the flexural strength and equivalent flexural strength according to age were also stably expressed, it could be seen that performance degradation due to hydrolysis, which is a concern due to the use of PET fiber reinforcing materials, did not occur, and it was confirmed that stable residual strength retention characteristics were exhibited.