Environmental, social, and governance (ESG) considerations have become increasingly important for firms' sustainability. Mandates for ESG information disclosure have been implemented in over 25 countries, including the EU, Australia, and China (Krueger et al., 2021). However, little attention has been paid to the drivers and mechanisms of ESG, which remain unclear. The existing literature has mainly focused on the consequences of ESG which shows mixed results and paid little attention to the drivers of ESG (Paolone et al., 2021). The majority of prior research suggests that ESG activities positively affect firms' financial performance (Nekhili et al., 2019). On the other hand, some researchers show a significant and negative relationship between ESG performance and a firm's financial performance (Duque-Grisales and Aguilera-Caracuel, 2021). To fill the research gap, this study attempts to identify 1) firms' internal and external factors that lead to ESG performance as drivers of ESG, and 2) firm performance as the consequences of ESG. The study found that environmental innovation activities, ESG committees, external audits, and ESG compensations related to environmental innovation could be drivers of ESG application and performance, leading to better firm performance. Moreover, the findings indicate that ESG performance positively affects firms' financial and non-financial performance. Understanding the adoption of ESG is crucial for firms since ESG requires a long-term perspective. This study contributes to the literature on ESG and firm sustainability and suggests new directions for managers to implement ESG in their business model. Especially, this study argues that taking a carrot-and-stick approach could lead to better ESG performance and firm performance. Therefore, managers might consider internal policies to encourage ESG that can lead to better firm performance.

The damage ratio of Spent Nuclear Fuel (SNF) is a very important intermediate variable for dry storage risk assessment which require an interdisciplinary and comprehensive investigation. It is known that the pinch load applied to the cladding can lead to Mode-3 failure and the cladding becomes more vulnerable to this failure mode with the existence of radial hydrides and other forms of mechanical defects. In this study, a sensitivity analysis was performed to evaluate the importance of the damage parameters that need to be calibrated for the simulation of zircaloy-4 cladding failure using computational mechanics. The simulation model was generated from a microscopic image of the cladding with hydride. The image segmentation method was used to separate the Zircaloy-4, hydride, and hydride- Zircaloy matrix interfaces to create a pixel-based finite element model. The ring compression test (RCT) was simulated because the resistance of the cladding under pinch load can be evaluated by this test. It was assumed that the damage starts with the formation and growth of voids or small cracks in the material, which grow and combine to form larger cracks, eventually leading to the complete fracture of the material. Therefore, the ductile damage criterion was applied to all materials to simulate crack formation and propagation. The sensitivity analysis was performed based on the design of experiments using L8 orthogonal array. The effects of five factors on the fracture resistance of hydrided cladding were quantified, and they are the fracture strains describing the damage initiation in zircaloy-4 matrix, hydride, and hydride-zirconium matrix, and yield stress and Young’s modulus for hydride-zirconium matrix. Information on those parameters are hardly available in literature and experimental data which enable the estimation of those are also very rare. It is planned to build a computational model which can accurately simulate the fracture behavior of hydrided cladding by calibrating significant fracture parameters using reverse engineering. The results of this study will help to figure out those significant parameters.

Considering the domestic situation where all nuclear power plants are located on seaside, the interim storage site is also likely to be located on coastal site. Maritime transportation is inevitable and the its risk assessment is very important for safety. Currently, there is no independently developed maritime transportation risk assessment code in Korea, and no research has been conducted to evaluate the release of radioactive waste due to the immersion of transport cask. Previous studies show that the release rate of radionuclides contained in a submerged transport cask is significantly affected by the area of flow path generated at the breached containment boundary. Due to the robustness of a cask, the breach is the most likely generated between the lid and body of cask. CRIEPI investigated the effect of cask containment on the release rate of radioactive contents into the ocean and proposed a procedure to calculate the release rate considering the so-called barrier effect. However, the contribution of O-ring on the release rate was not considered in the work. In this study, test and analysis is performed to determine the equivalent flow path gap considering the influence of O-rings. These results will be implemented in the computational model to assess sea water flow through a breached containment boundary using CFD techniques to assess radionuclide release rates. The evaluation of release rate due to container lid gaps has been performed by CRIEPI and BAM. In CRIEPI, the gap of the flow path was calculated from the roughness of the container surface without a quantitative assessment of the severity of the accident. In this work, to evaluate the release rate as a function of lid displacement, a small containment vessel is engineered and a metal Oring of the Helicoflex HN type is installed, which is the most commonly used one in transport and storage casks. The lid of containment vessel is displaced in vertical and horizontal direction and the release rate of the vessel was quantified using the helium leak test and the pressure drop test. Through this work, the relationship between the vertical opening displacement and horizontal sliding displacement of the cask lid and the actual flow path area created is established. This will be implemented in the CFD model for flow rate calculation from a submerged transport cask in the deep sea.

The optimum vitrification conditions of the radioactive waste using high-temperature furnace and HIP (Hot Isostatic Press) were studied for the successful reduction of the solidification volume, radioactive level, satisfying the disposal criteria such as leaching rate and compressive strength. Vitrification is receiving attention for the solidification disposal of intermediate and low-level radioactive wastes for its chemical-physical stability and leachability. Its principle is to trap the radioactive material in a fixed structure of the glass type materials, such as Boron Trioxide, Silicon Dioxide and Phosphorus Pentoxide. Sludge targeted in this study is assembly of materials while sludge is stored in the stainless-steel tank before disposal, which consists of Fe3O4 (14.9wt%), Fe2O3 (3.8wt%), and Cr2O3 (6.3wt%), cement paste (25wt%) and detergent/shower sludge (50wt%). The detergent/shower sludge generated from the washing the clothes that were worn during the work at the laboratory and nuclear power plant contains organic materials that are vulnerable to chemical reactions, therefore, immobilization of organic material by the incinerating step, which can also immobilize the radioactive substance, was applied. Its composition – containing Cs-133 and Co-59 substitution for Cs-134 and Co-60 that are radioactive – was analyzed by XRD before and after the mineralization of the sludge using high temperature furnace in different temperature, to identify the remaining element and the features of the mineralized sludge. Targeted sludge was vitrificated using Hot Isostatic Press in with different pressure and temperature conditions, to find out the optimum vitrification conditions. Vitrificated waste was evaluated in many aspects - leaching evaluation following ANS16.1, compressive strength evaluation of 3.44 MPa (waste disposal criteria), volume reduction before and after the sequence.

The evaluation of the damage ratio of spent nuclear fuel is a very important intermediate variable for dry storage risk assessment, which requires an interdisciplinary and comprehensive investigation. It is known that the pinch load applied to the cladding can leaded to Mode-3 failure and the cladding becomes more vulnerable to this failure mode with the existence of radial hydrides and other forms of mechanical defects. In this study, the failure resistance of Zircaloy-4 cladding against the pinch load is investigated using numerical simulations assuming the existence of radial hydrides. The simulation model is based on the microscopic images of cladding. A pixel-based finite element model was created by separating the Zircaloy-4 and hydride using the image segmentation method. The image segmentation method uses a morphology operation basis, which is a preprocessing method through erosion operation after image expansion to enable normal segmentation by emphasizing pixels corresponding to hydrides. The segmented images are converted into a finite element model by assigning node and element numbers together with corresponding material properties. Using the generated hydride cladding finite element model, several numerical methods are investigated to simulate crack propagation and cladding failure under pinch load. Using extended finite element (XFEM) models the initiation and propagation of a discrete crack along an arbitrary, solution-dependent path can be simulated without the requirement of remeshing. The applicability of fracture mechanical parameters such as stress intensity, J-integral was also investigated.

Colony collapse disorder (CCD), a phenomenon of honeybees disappearance, has been reported since 2006. Chronic exposure to neonicotinoid insecticides, particularly imidacloprid, has been suggested to impair forager’s ability for foraging and be a main cause of CCD. Recently, it has been reported that imidacloprid induces insulin resistance in animal cell line by blocking glucose uptake. Similarly to human insulin, insulin-like peptide (ILP) of insects is involved in maintaining blood glucose contents in hemolymph by regulating the concentration of trehalose and glycogen. Therefore, we have hypothesized that sublethal concentration of neonicotinoid may affect the metabolic pathway of honey bees as well. We investigated the transcription levels of the genes involved in the insulin/insulin-like signaling (IIS) pathway, such as AmILP and AmInR, following an acute or a chronic dietary exposure of sublethal concentrations of imidacloprid to foragers. In both experiments, honeybees showed increased expression levels of ILP and InR in a dose-dependent manner. Our results suggest that sublethal dose of imidacloprid likely upregulates IIS pathway, thereby rendering honey bees to become resistant to insulin.

Various ecosystem carry out fundamental function of material circulation and energy flow through interrelationship with many environmental factors. Therefore, it is crucial to scientifically understand the value of nature to deduce correlation between environmental factor and change of ecosystem function. In this study, we determined the accumulated ecosystem carbon and characteristics of soil respiration on grassland vegetation in Namahangang basin in Namhangang Basin. It was found that the rate of soil respiration was highly correlated with the soil temperature in all communities. The measured soil respiration rates were 1,539 mgCO2 m-2 h-1, 1,200 mgCO2 m-2 h-1, 1,215 mgCO2 m-2 h-1 in Miscanthus sacchariflorus, Phragmites japonica, Salix koreensis communities, respectively. Also, carbon quantities accumulated in litter and soil layers were 40.6 tCha-1 (1.9+38.7), 46.9 tCha-1 (43.0+3.9), 31.2 tCha-1 (28.9+2.3) in M. sacchariflorus, P. japonica, S. koreensis communities, respectively.

Distribution and abundance of birds have close relationship with the characteristics of habitats. Especially in breeding season, stable place to build up nests, food items for offspring and existence of available mates are important factors affecting successful reproduction. Therefore, breeding bird community varies according to the specific breeding habits for each species and environmental characteristics. Mt. Halla is located center of Jeju island and consists of different vegetation according to the elevation. In lowland, Seonheul with 100m elevation has wetlands and evergreen broad leaved forests lies while mixed forest and Korean fir (Abies koreana) community in higher elevation. Mixed forest in Mt. halla was designated as gene conservation forest by Korea Forest Service because of its is high quality of preservation and is located in 1,200m elevation. Abies koreana forest in 1,300m elevation consists of mainly Korean fir (Abies koreana) that is endemic species in Korea, but is susceptable to wind and soil quality because of its shallow and spreading root system and recently being damaged due to the climate change. To investigate breeding bird community in Mt. Halla, bird census was conducted from April to August, 2011 to 2013. A total of 17 species which consists of 17 species in Seonheul, 9 species in the mixed forest, and 7 species in Abies koreana forest were observed during the study period. Community indices such as species diversity, evenness, and richness index were almost consistent yearly but changed according to the study sites. In Seonheul, diversity and richness index were much higher than in others. Mixed forest had slightly higher diversity and richness index than Abies koreana forest. According to the correspondence analysis(CA), bird community in Seonheul showed distinctive difference with that in mixed forest and Abies koreana forest. Similarity in bird community was higher in Seonheul, compared to that in mixed forest and Abies koreana forest. Bird species and individuals were more abundant in Seonheul. Nesting guilds were classified as ground, bush, canopy, hole, brood parasite, and artificial structures. All sites had the same composition of nesting guild across all three years. In Seonheul, variability of nesting guilds was greatest including ground, brood parasite, and artificial structures which were not observed in the other sites. In Seonheul, the number of species that bred in canopy was largest and in mixed forest and Abies koreana forest, the number of species that bred in hole was the greatest indicating most of the bird species used tall trees as nesting sites. The number of individuals in the entire sites tended to decrease yearly. The number of individuals that bred in canopy was greatest in Seonheul but decreased across years as well as in bush and hole. In Abies koreana forest, the number of hole nesters and the birds breed in canopy tended to decrease from 2011 to 2013. Foraging guilds were categorized into ground, bush, canopy, and air. The number of species consisiting foraging guilds was the same from 2011 to 2013 throughout study sites. The most preferred foraging guild was ground in Seonheul(7 species), while canopy in the mixed forest(6 species) and Abies koreana forest(5 speices). Also, the species foraged in the air, the barn swallow and the japanese paradise flycatcher were observed only in Seonheul. The average number of individuals that foraged in canopy, 50 individuals, was greatest in all the sites across all three years and the following was in ground consisting 32 individuals. The number of individuals that foraged in canopy which mainly comprised of great tits, varied tits,and japanese white-eyes, tended to decrease in Seonheul, 80 to 44 and Abies koreana forest, 46 to 24 from 2011 to 2013, except mixed forest in which the number of these increased. In Seonheul, the number of individuals foraged in air tended to increase because of the sudden increment in the number of barn swallows: 24 individuals in 2011 to 52 in 2013 as shown in the number of individuals nested in artificial structures. Since Seonheul provides diverse habitats such as wetlands, various vegetation structures and high coverage of tree layer, many different bird species inhabit. Barn swallows and japanese paradise flycatchers which forage for these flying in the air were observed in Seonheul and it seems that this is because the environment seems suitable for insects. Generally tall trees were most favored as nesting and foraging place in all the study sites. For example, the japanese paradise flycatcher and the fairy pitta which favor dark area seemed to have bred in Seonheul, because of the high coverage of tall trees blocked sunlight enough. Also, Family Paridae such as great tits and varied tits nested in holes in tall trees. Furthermore, Family Paridae, japanese white-eyes and brown-eared bulbuls foraged for insects and fruits on tall trees, occupying the largest portion in terms of the number of individuals in foraging guilds. Despite this high usage of tall trees, these are now being lost in Seonheul and Abies koreana forest. Especially in Seonheul, Pinus thunbergii that infected by Bursaphelenchus xylophilus are logged out since October, 2013, deteriorating habitat quality. Furthermore in Abies koreana forest, almost half of the Abies koreana has died and 20.7% of them died since 2011 mainly due to the climate change, according to the Mt. Halla research institute. Such environmental change might have caused decrease in the number of individuals that rely on the tall trees for both nesting and foraging place such as white-backed woodpeckers, great tits, coal tits, varied tits and brown-eared bulbuls. From 2011 to 2013, average daily temperature increased rapidly and average maximum temperature in March, right before egg laying period, increased by 4℃ compared to that in 2011. It has been reported that abrupt change in early breeding period could result in decreased reproduction success rate because of mismatch of time between hatching period and time when caterpillar abundance is high enough to feed nestlings. Therefore, the average temperature increase also might have caused decreased individual number of the species in great tits and varied tits.