• Korean Journal of Plant Resources
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• v.22 no.5
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• pp.461-466
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• 2009

This study was carried out to evaluate the effects of yam (Dioscorea batatas Dence) extracts on the cell viability, growth and nucleus-DNA damage of tobacco cells which were exposed to $\gamma$-radiation stress. The viability and growth of tobacco cells exposed to 20 Gy of radiation stress were effectively recovered by pretreatment of 10 mg/L ethylacetate (EtOAc) yam extract. Pretreatment of EtOAc extract showed 20% higher cell viability and fresh weight growth than that of cells without pretreatment in 20 Gy radiation treated tobacco cells. Nucleus-DNA damage was measured as the ratio of tail length (T) to head length (H) in individual comet image isolated from tobacco cells. The T/H ratio of control-cells and treated-cells at 20 Gy were 1.05 and 1.68, and % head DNA of those cell were 86.7 and 71.3%, respectively, suggesting that nuclei of tobacco cells were severely damaged in the integrity of DNA by the treatment of $\gamma$-radiation. However, pretreatment of MeOH, EtOAc and n-BuOH extracts decreased radiation induced DNA-damage in the tobacco cells, showing T/H ratio of 1.37, 1.01 and 1.10 and % head DNA of 81.5, 87.6 and 88.7%, respectively.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.297-306
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• 2017

The concrete median barrier used currently in South Korea was developed the impact level of SB5-B(270kJ). However, the impact level of SB6(420kJ) should be considered in many placed with the increased accident of heavy vehicles. In order to increase the impact resistance of newly developed concrete median barrier, the computer simulation was conducted before real field test. For the accurate behavior of concrete, the parameter, such as impact vehicle, concrete cover depth and deterioration, was important. In this paper, a parametric study was conducted depending on vehicle curb weight, concrete cover depth and level of deterioration. The impact resistance of concrete median barrier was severely changed depending on vehicle curb weight and concrete cover depth. Furthermore, the impact resistance of concrete median barrier was also decreased due to deterioration of concrete, therefore the repair and rehabilitation should be conducted for damaged concrete depending on deterioration level. Therefore, vehicle curb weight, cover depth of concrete structures and deterioration level of concrete should be carefully considered for conducting analysis of concrete structure to vehicle collision.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.3 s.55
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• pp.23-31
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• 2007

Fast bridge construction has been increasingly needed according to the changed construction environment. This paper deals with quasi-static tests on precast piers for bridge substructures. One of the most crucial aspect of the design of precast prestressed concrete bridge piers is the seismic performance. Seven precast pier elements were fabricated. The amount of prestressing bars, the prestressing force, and the location and number of the joint between segments were the main test parameters. Test results showed that the introduced axial prestress made the restoration of the deformation under small lateral displacement and minor damage. However, there was no effect of the prestress when the plastic hinge region was damaged severely due to large lateral displacement. Judging from the observed damage, the design of the joints in precast piers should be done for the first joint between the foundation and the pier segment. The amount of the necessary prestressing steel may be designed to satisfy the P-M diagram according to the service loads, not by having the same steel ratio as normal RC bridge piers. In order to satisfy the current required displacement ductility, it is necessary to have the same amount of the transverse reinforcements as RC piers. As the steel ratio increases, the energy absorption capacity increases. The number of joints showed a little influence on the energy absorption capacity.

• Journal of The Geomorphological Association of Korea
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• v.19 no.1
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• pp.17-27
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• 2012

Coastal dunes help stabilize the coastal landscape and protect the hinterland through dynamic interaction with sand beaches. Sometimes dune erosion occurs during the tropical cyclones, while dune recovery may naturally follow after the event. As the typhoon Kompasu passed through the Korean Peninsula early-September in 2010, it caused a rise in water in association with the storm, wave run-ups, and heavy rains in coastal areas. As the result, coastal dunes along the west coast of Korea were severely damaged during the storm. However, the degree and extent of erosion and recovery of dunes were found to be related with the condition of beach-dune systems including gradients of foreshore and front slope of the dune, sediment supply, vegetation, wind activity, and human interferences. Some dunes retreated landward more and more after the erosional event, while others recovered its original profile by aeolian transport processes mainly during the winter season. Vegetated dunes with pine trees were less recovered after the erosion than grass-covered dunes. In addition, dunes with artificial defense were more eroded and less recovered than those without hard constructions. According to the observation after the severe storm, it is likely that the sand transport process is critical to the dune recovery. Therefore, the interactions between beach and dune must be properly evaluated from a geomorphological perspective for the effective management of coastal dunes, including natural recovery after the erosion by storm events.

• Conservation Science in Museum
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• v.25
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• pp.51-62
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• 2021

The Belt with Rhinoceros-Horn Ornaments(known as a seodae in Korean) from the family of Princess Deokon's descendants housed in the National Hangeul Museum underwent emergency treatment for a special exhibition in 2019 upon the request of the National Hangeul Museum. Priority was given to the restoration of the original form of the severely damaged belt and the repair of its detached horn ornaments. Prior to the conservation treatment, researchers conducted a theoretical study of the belt with rhinoceros-horn adornments to learn the names of its structural components and the changes in form that the type experienced by period, thereby establishing a plan for conservation treatment and setting a direction. Among the belts worn by officials from the Joseon dynasty, rhinoceros-horn ornaments were attached to those of officials of the first rank and were considered the most precious behind the king's belt with its jade ornaments. The rhinoceros horn adorning the belt is classified into three categories according to quality. This belt has horn adornments of the highest quality, falling under the "grape design" category with dark brown dots concentrated in the center. The belt has a rectangular shape and lacks a buckle, reflecting a popular form from the nineteenth century. The structure of the belt was identified over the process of conservation treatment, offering information about its method of production. In addition, comparison of the relic with belts with rhinoceros-horn ornaments depicted in Joseon-period portraits of officials allowed the identification of changes in formal features and the detailed structures of belts with rhinoceros-horn ornaments by period. It confirmed that the belt subject to conservation treatment shows the features of belts with rhinoceros-horn ornaments produced in the nineteenth and twentieth centuries.

• Journal of Industrial Convergence
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• v.20 no.3
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• pp.1-10
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• 2022

The results(Boje et al. 2004) suggest that corporate image is severely damaged due to arrogance and a sense of power among some of the executives. With the advent of the MZ generation, the humility of leaders who lead the organization becomes more and more important(Morris et al. 2005; Vera, Rodriguez-Lopez, 2004; Owens et al. 2013). This paper tried to empirically analyze the mediating effect of emotional regulation in the relationship between humble leadership, voice behavior, and innovative behavior. To this end, a survey was conducted from November to December 2021 for corporate employees in Busan, Gyeongnam, and Gyeongbuk, and was empirically analyzed through the results of a total of 145 surveys. As a result, it was verified that humble leadership had a positive(+) effect on voice behavior and innovative behavior, and the mediating effect of emotional regulation in the relationship between humble leadership and voice behavior and innovative behavior was also verified. Through this, this study expanded the scope of research by newly illuminating the relationship between humble leadership and emotional regulation, which are the core competencies of leaders, and revealing the causal relationship. In future research, we intend to explore the relationship between humble leadership and various variables and to investigate the relationship through various research methods.

• Journal of Digital Convergence
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• v.20 no.5
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• pp.85-92
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• 2022

In recent years, the world's free trade system has been severely damaged by a series of protectionist measures in the United States and anti-globalization practices such as Brexit. Against this background, RCEP, the world's largest trade agreement, was officially signed on November 15, 2021. The RCEP provided a good working basis for the establishment of a Korea, China, and Japan free trade zone. First, this paper describes the current status of Korea-China-Japan trade cooperation and the current status of the trilateral telecommunication industry. Second, this paper simulates the changes in the overall economy of China, Japan, and Korea when tariffs are reduced to 0%, 5%, and 10%, respectively, after the establishment of a free trade zone using the 8th edition GTAP database. Then, using the simulated data changes and using the 2019 data as a benchmark, we calculated the changes in the RCA index for the three countries' telecommunications industries for the three tax rates. In the end, it is concluded that the economies of the three countries will grow to different levels in many ways when the Korea, China, and Japan free trade zone is established. Japan's telecommunications industry will not be significantly affected, Korea will grow significantly with higher tax rates and China will grow significantly with lower tax rates.

• Journal of the Korea Institute of Building Construction
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• v.22 no.1
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• pp.91-102
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• 2022

Many industries are being severely damaged by COVID-19, a respiratory infection that has recently been prevalent around the world. In particular, for workers in the construction industry, it is impossible to work from home, and if an outbreak on a construction site is confirmed, it can lead to great damage. Accordingly, the government has drafted 「Guidelines for Response to Construction Sites for Prevention and Spread of COVID-19」. In addition, domestic and foreign research about COVID-19 in the field of construction sites is being actively conducted. However, Korea has lacked studies on the effectiveness of the countermeasures in place at construction sites, or that reflect the opinions of construction site workers. Therefore, this study conducted a survey of construction site workers by dividing the construction of the COVID-19 quarantine management system and response plan into on-site management and social management. Through the AHP/IPA analysis, it was found that among social management, 'infectious disease management system and cooperation system with related institutions' and 'reduction of working hours' are areas with high importance but low satisfaction. After that, the causes of the two items were analyzed and related countermeasures were suggested. The results of this study will be able to contribute to the improvement of the quarantine management system and response plan at construction sites, and to minimize the damage to the construction industry related to COVID-19.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.3
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• pp.198-205
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• 1982

In 1980, rice was considerably damaged by abnormal low temperature. In this paper, to determine the effect of low temperature on the growth and nutrition of rice, the experiment were carried out: varietal response to low temperature in the region with different elevations. Regional differences of heading response to low temperature were observed among varieties. The difference of days between regions were bigger in tongil lines than Japonica lines. Especially, Milyang 42 and Hangangchalbeo might belong the cold suceptible group, since the varieties were severely delayed their heading in the high mountainous region as comparred to plain region. The delay of heading with low temperature was brought out grain sterility, and fertility and ripening ratio is influenced cold tolerance and elevations, and it's decreased yield. Varieties with higher grain sterility by low temperature have higher total nitrogen content, but tended to have lower potassium and phosphate contents in the flag leaf. High content of total nitrogen, low contents of potassium and silicate were observed in the sterilized grain chaff an the opposite result were noted in the ferilized grain chaff at the ripening stage. The results reveal that the balance of these mineral element may play an important role in ripening and possibly cold tolerance.

• Geomechanics and Engineering
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• v.32 no.3
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• pp.307-319
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• 2023

Ground fissures have a huge effect on the integrity of surface structures. In high-intensity ground fissure regions, however, land resource would be wasted and city building and economic development would be limited if the area avoiding principle was used. In view of this challenge, to reveal the seismic response and seismic failure characteristics of ground fissure sites, a shaking table test on model soil based on a 1:15 scale experiment was carried out. In the test, the spatial distribution characteristics of acceleration response and Arias intensity were obtained for a site exposed to earthquakes with different characteristics. Furthermore, the failure characteristics and damage evolution of the model soil were analyzed. The test results indicated that, with the increase in the earthquake acceleration magnitude, the crack width of the ground fissure enlarged from 0 to 5 mm. The soil of the hanging wall was characterized by earlier cracking and a higher abundance of secondary fissures at 45°. Under strong earthquakes, the model soil, especially the soil near the ground fissure, was severely damaged and exhibited reduced stiffness. As a result, its natural frequency also decreased from 11.41 Hz to 8.05 Hz, whereas the damping ratio increased from 4.8% to 9.1%. Due to the existence of ground fissure, the acceleration was amplified to nearly 0.476 m/s², as high as 2.38 times of the input acceleration magnitude. The maximum of acceleration and Arias intensity appeared at the fissure zone, which decreased from the main fissure toward both sides, showing hanging wall effects. The seismic intensity, duration and frequency spectrum all had certain effects on the seismic response of the ground fissure site, but their influence degrees were different. The seismic response of the site induced by the seismic wave that had richer low-frequency components and longer duration was larger. The discrepancies of seismic response between the hanging wall and the footwall declined obviously when the magnitude of the earthquake acceleration increased. The research results will be propitious to enhancing the utilizing ratio of the limited landing resource, alleviation of property damages and casualties, and provide a good engineering application foreground.