• Korean Journal of Environment and Ecology
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• v.32 no.3
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• pp.274-288
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• 2018

This study investigated the environmental factors and fish assemblage in 42 wetlands between spring and autumn of 2017 to evaluate the fish distribution and deduce the management strategy for improving biodiversity in created wetlands located at the Nakdong River basin. The investigation identified a total of 30 fish species and found that the most of wetlands were dominated by exotic fishes such as Micropterus salmoides and Lepomis macrochirus. Fish species such as Rhinogobius brunneus, Opsariichthys uncirostris amurensis, Zacco platypus were less abundant in the area with high density of Micropterus salmoides (static area) because they preferred the environment with active water flow. The pattern analysis of fish distribution in each wetland using the self-organizing map (SOM) showed a total of 24 variables (14 fish species and 10 environmental variables). The comparison of variables indicated that the distribution of fish species varied according to water depth and plant cover rate and was less affected by water temperature, pH, and dissolved oxygen. The plant cover rate was strongly associated with high fish density and species diversity. However, wetlands with low plant biomass had diversity and density of fish species. The results showed that the microhabitat structure, created by macrophytes, was an important factor in determining the diversity and abundance of fish communities because the different species compositions of macrophytes supported diverse fish species in these habitats. Based on the results of this study, we conclude that macrophytes are the key components of lentic freshwater ecosystem heterogeneity, and the inclusion of diverse plant species in wetland construction or restoration schemes will result in ecologically healthy food webs.

• Journal of Korean Neurosurgical Society
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• v.61 no.6
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• pp.680-688
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• 2018

Objective : To mitigate the risk of iatrogenic instability, new posterior decompression techniques able to preserve musculoskeletal structures have been introduced but never extensively investigated from a biomechanical point of view. This study was aimed to investigate the impact on spinal flexibility caused by a unilateral laminotomy for bilateral decompression, in comparison to the intact condition and a laminectomy with preservation of a bony bridge at the vertebral arch. Secondary aims were to investigate the biomechanical effects of two-level decompression and the quantification of the restoration of stability after posterior fixation. Methods : A universal spine tester was used to measure the flexibility of six L2-L5 human spine specimens in intact conditions and after decompression and fixation surgeries. An incremental damage protocol was applied : 1) unilateral laminotomy for bilateral decompression at L3-L4; 2) on three specimens, the unilateral laminotomy was extended to L4-L5; 3) laminectomy with preservation of a bony bridge at the vertebral arch (at L3-L4 in the first three specimens and at L4-L5 in the rest); and 4) pedicle screw fixation at the involved levels. Results : Unilateral laminotomy for bilateral decompression had a minor influence on the lumbar flexibility. In flexion-extension, the median range of motion increased by 8%. The bone-preserving laminectomy did not cause major changes in spinal flexibility. Two-level decompression approximately induced a twofold destabilization compared to the single-level treatment, with greater effect on the lower level. Posterior fixation reduced the flexibility to values lower than in the intact conditions in all cases. Conclusion : In vitro testing of human lumbar specimens revealed that unilateral laminotomy for bilateral decompression and bone-preserving laminectomy induced a minor destabilization at the operated level. In absence of other pathological factors (e.g., clinical instability, spondylolisthesis), both techniques appear to be safe from a biomechanical point of view.

• Journal of Conservation Science
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• v.34 no.6
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• pp.443-458
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• 2018

An archive is a collection of documents or records. Currently, most archived documents are made of paper. Paper is susceptible to biological damage and deterioration due to its material properties. To control the biological damage, treatment with chemical disinfectants and control of the storage environment are often used. In government-controlled bulk public archives, all documents are chemically sterilized before storage. However, an extremely large quantity of public records have been produced, and storage space and conservation management are gradually reaching their limits. In this study, 60 species of microbes were identified using a genetic method. We successfully applied the adenosine triphosphate (ATP) bioluminescence method to detect microbial contamination on paper documents. A calibration curve of the ATP bioluminescence as a function of the microbe quantity was obtained, and the microbial activity on non-sterilized paper archives from 1951 was analyzed using an ATP luminometer. It was found that the microbial activity was suppressed or reduced in climate-controlled storage environments at $22^{\circ}C$ and 55% relative humidity. We anticipate that these results will be used to establish selective sterilization systems for government-controlled bulk public archives.

• Journal of Conservation Science
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• v.34 no.6
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• pp.581-593
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• 2018

Studies on ancient iron production technologies still have challenges to overcome, although there have been many results that have enabled us to understand these old technologies. The purpose of this study is to propose a suitable temperature condition for smelting experiments. The target for reconstruction is a smelting-smithing process in the ancient Jungwon area, and the experiment was designed on the basis of published research, such as archaeological evidence. Experiment A was performed at a low temperature to produce low-carbon iron, while Experiment B was conducted at a relatively high temperature to synthesize high-carbon iron. In addition, the low-carbon iron proved to be suitable for the smithing process. Moreover, aspects such as the microstructure and chemical composition of the slag and the surface condition of the furnace wall showed that the low-temperature smelting process was closer to the ancient method. It is important to mention the premise that the reconstruction of ancient technology can be achieved when the results of an experiment replicate the conditions of a real site. The results show that direct smelting, which produces low-carbon iron bloom under a low-temperature condition, should be the subject of smelting experiments concerning the iron production technologies of the ancient Jungwon area.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.9-19
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• 2021

This paper deals with the reinforcement performance of acrylate for reinforcing the settled railway roadbed. Concrete tracks have the advantage of reducing track maintenance costs and high resistance to track destruction. However, roadbed settlement is occurring in some construction sections, and the safety of railways is a serious concern because of difficulties in maintenance. Currently, maintenance through the track restoration method is being carried out in Korea as a way of roadbed settlement in concrete tracks, but continuous re-settlement can occur because the roadbed itself cannot be reinforced, and there are very few cases of reinforcement of railway roadbeds and field application. So the development of reinforcement materials and construction methods to reinforce railway roadbeds is required. Therefore, in this paper, acrylate was selected as reinforcement material for railway roadbed, and the reinforcement performance of acrylate was analyzed through experiment. As a result, it was analyzed that the acrylate can penetrate into a permeability coefficient of 1×10^-4 cm/sec, and secure uniaxial compression strength of 0.5 MPa/30min or more and stiffness of 80 MPa or more.

• Korean Journal of Plant Resources
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• v.36 no.4
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• pp.381-389
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• 2023

The germination characteristics of Pseudolysimachion kiusianum var. diamantiacum (Nakai) T.Yamaz., a rare and endemic plant designated by the Korea Forest Service, were investigated according to light conditions, temperature, and pretreatment. As a result of the germination experiment according to light conditions, it was determined that P. kiusianum is a photoblastic seed that does not germinate at all in dark conditions. The optimum germination temperature of the seeds was found to be 20-25℃, considering the final germination rate and germination time. Three growth regulators (IAA, GA₃, kinetin) and two inorganic salts (KNO₃, KCl) were pretreated to improve the germination rate of P. kiusianum seeds. The growth regulators IAA and kinetin had no significant effect on improving the germination rate of P. kiusianum seeds. On the other hand, GA₃ significantly increased the final germination percentage and germination rate regardless of the concentration, especially the treatment of more than 500 mg·L^-1 at 20℃ was more than 4 times more effective than the untreated. The inorganic salts KNO₃ and KCl had no significant effect on the seeds of P. kiusianum at low concentrations, but at higher concentrations (40 mM and 300 mM, respectively), they improved the germination rate and germination age by 2 times compared to the untreated. The results of this study will be useful for the mass propagation of P. kiusianum, which has the potential to be utilized as a native plant for restoration.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.58-64
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• 2024

Approximately 250 marine oil spill accidents have occurred in Korea, with profound impact on local communities and the environment. The restoration process necessitates significant resources and costs to return affected areas to their pre-accident state. In accordance with the polluter pays principle, compensation is demanded from polluter, as stipulated in both international conventions and national laws. Consequently, investigations are conducted to determine civil and criminal liability. As the importance of investigation actors in oil spill accidents increases, standards such as CEN 15522-2 and ASTM D 3248 are employed to determine the similarity between the spilled oil and the oil of the suspected ship. Among these standards, CEN 15522-2, the most actively used European standard, underwent its third revision and is now known as EN 15522-2, as of 2023. This study used EN 15522-2 to analyze samples from marine oil spill accidents that occurred in Korea. The results indicated that, considering the characteristics of domestic spills where light fuel oil spills account for more than 40%, the application of EN 15522-2, which includes low-boiling point substances such as Adamantanes, was confirmed to be highly effective.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.254-263
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• 2007

The objective of this study was to evaluate biological water quality using fish assemblages in Nakdong River watershed. We selected 6 sites along the main axis of the river and evaluated the Index of Biological Integrity (IBI), Qualitative Habitat Evaluation Index (QHEI) and chemical water quality during July 2004${\sim}$March 2006. For the study, we applied the 10 metric IBI model, which was developed for national biological water quality criteria. Nakdong River's IBI value averaged 20.8 (n=14) during the study which means poor biological water quality. Physical habitat health at all sites, based on QHEI model, was measured as 110, indicating fair${\sim}$good condition. The habitat health varied depending on the locations sampled. Habitat health in sites 1 and 6 was judged as good, while the health in sites 3 and 4 was $poor{\sim}fair$. Especially, we found the metric values of $M1{\sim}M5$, M7, M10 were low in sites 3 and 4 compared to other sites. In these sites, thus, habitat restoration of substrate composition, riffles, and bank vegetation may be necessary. In the mean time, chemical water quality, based on BOD, COD, TSS, and nutrients, had no large spatial and temporal variations. Overall data analysis indicated that site 3 was largely impacted by the polluted-tributary, Keumho River and the downstreams showed better water quality due to the dilution of the polluted river water by Nam River and Hwang River.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.323-330
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• 2013

This study was conducted to know the effect of major physical-chemical characteristics of soil to be in the area of indigenous and naturalized plant in the sand dune of the western coastal area of Korea. The study was performed on the sand dunes distributed across Taean-gun and Buan-gun and the study period was from April to October in 2010. Sixty nine of $5m{\times}5m$ study plots were installed and the distribution of plants were investigated. We measured the soil characteristics including soil pH, organic matter, total nitrogen, available $P_2O_5$, soil cation exchange capacity, exchangeable cation, EC and NaCl. As a result, soil texture was classified as sand, in case of average pH, NaCl, and EC of soil to be in the area of indigenous herbaceous plant were 7.77, 0.03% and $0.52ds.m^{-1}$, indigenous woody plant of the mean pH, NaCl and EC were 7.31, 0.01%, $0.23ds.m^{-1}$. In case of naturalized herbaceous plant of the mean soil pH, NaCl and EC were 7.12, 0.01%, $0.29ds.m^{-1}$, naturalized woody plant of the mean soil pH, NaCl and EC were 7.34, 0.01%, $0.20ds.m^{-1}$ respectively. On average, naturalize plants showed in low salinity concentration than indigenous plants.

• Korean Journal of Heritage: History & Science
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• v.54 no.2
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• pp.22-37
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• 2021

The wind chime is a longstanding Jangeomgu (majestic article) found in Korea, China, and Japan. However, basic research on wind chimes is currently inadequate as it is difficult to estimate the time of production, and there are few relics. Therefore, this research morphologically classifies the eight bronze wind chimes decorating the baldachin of the Stone Standing Maitreya Bodhisattva of Gwanchoksa Temple, Nonsan. Based on this, the manufacturing techniques and production period are scientifically demonstrated. The synthesis of the research results reveals that the structure and characteristics of the wind chimes of the Stone Standing Maitreya Bodhisattva of Gwanchoksa Temple, Nonsan differ depending on their location on the baldachin. The four large-sized wind chimes on the lower-baldachin were manufactured by casting a Cu-Sn-Pb alloy, and they are estimated to have been made during the early period of Goryeo. The two medium-sized wind chimes of the upper-baldachin's northern direction were manufactured through forging a Cu-Sn or Cu-Sn-Pb alloy, and they appear to have a similar structure to the cylindrical wind chimes appearing during the latter period of Goryeo and the Joseon period. The two small-sized wind chimes of the upper-baldachin's southern direction were manufactured by casting a Cu-Sn-Pb alloy containing Zn, and based on the chemical composition of the alloy and the shape of the clapper, they are estimated to have been manufactured during the latter period of Joseon. Through the observation of microstructures and a chemical composition analysis, it is demonstrated that two wind chimes of the lowerbaldachin were manufactured by casting and slow cooling the alloy with an alloy ratio of Cu:Sn:Pb≒80:15:5. In addition, it is estimated that the wind chimes of the upper-baldachin's northeast direction were manufactured by forging an alloy of Cu-Sn with a similar alloy ratio to that of forged high tin bronze. The results of a comparative analysis of prior research on domestic wind chimes confirm that two wind chimes of the lower-baldachin have a similar composition ratio to the wind chime excavated from Wolnamsaji in Gangjin, containing an amount of tin that corresponds with ancient records. Having a similar alloy ratio to forged high tin bronze, the wind chimes of the upper-baldachin's northeast direction are the only instances among all of the wind chimes that have been examined to date that were manufactured using this forging method. The purpose of this research is to collect baseline data to verify and classify the manufacturing period of wind chimes according to their morphological characteristics based on scientific evidence. It is hoped that this data can be utilized for the restoration and conservation processes of the wind chimes of the Stone Standing Maitreya Bodhisattva of Gwanchoksa Temple, Nonsan.