• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.3017-3029
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• 2023

In the late in-vessel phase of a nuclear reactor severe accident, the internal heat transfer and crust evolution during the debris bed melting process have important effects on the thermal load distribution along the vessel wall, and further affect the reactor pressure vessel (RPV) failure mode and the state of melt during leakage. This study coupled the phase change model and large eddy simulation to investigate the variations of the temperature, melt liquid fraction, crust and heat flux distributions during the debris bed melting process in the hypothetical severe accident of HPR1000. The results indicated that the heat flow towards the vessel wall and upper surface were similar at the beginning stage of debris melting, but the upward heat flow increased significantly as the development of the molten pool. The maximum heat flux towards the vessel wall reached 0.4 MW/m². The thickness of lower crust decreased as the debris melting. It was much thicker at the bottom region with the azimuthal angle below 20° and decreased rapidly at the azimuthal angle around 20-50°. The maximum and minimum thicknesses were 2 and 90 mm, respectively. By contrast, the distribution of upper crust was uniform and reached stable state much earlier than the lower crust, with the thickness of about 10 mm. Moreover, the sensitivity analysis of initial condition indicated that as the decrease of time interval from reactor scram to debris bed dried-out, the maximum debris temperature and melt fraction became larger, the lower crust thickness became thinner, but the upper crust had no significant change. The sensitivity analysis of in-vessel retention (IVR) strategies indicated that the passive and active external reactor vessel cooling (ERVC) had little effect on the internal heat transfer and crust evolution. In the case not considering the internal reactor vessel cooling (IRVC), the upper crust was not obvious.

• International Journal of High-Rise Buildings
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• v.12 no.2
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• pp.129-136
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• 2023

Natural ventilation has proven to be an effective passive strategy in improving energy efficiency and providing healthy environments. However, such a strategy has not been commonly adopted to tall office buildings that traditionally rely on single-skin façades (SSFs), due to the high wind pressure that creates excessive air velocities and occupant discomfort at upper floors. Double-skin façades (DSFs) can provide an opportunity to facilitate natural ventilation in tall office buildings, as the fundamental components such as the additional skin and openings create a buffer to regulate the direct impact of wind pressure and the airflow around the buildings. This study investigates the impact of modified multi-story type DSFs on indoor airflow in a 60-story, 780-foot (238 m) naturally ventilated tall office building under isothermal conditions. Thus, the performance of wind effect related components was assessed based on the criteria (e.g., air velocity and airflow distribution), particularly with respect to opening size. Computational fluid dynamics (CFD) was utilized to simulate outdoor airflow around the tall office building, and indoor airflow at multiple heights in case of various DSF opening configurations. The simulation results indicate that the outer skin opening is the more influential parameter than the inner skin opening on the indoor airflow behavior. On the other hand, the variations of inner skin opening size help improve the indoor airflow with respect to the desired air velocity and airflow distribution. Despite some vortexes observed in the indoor spaces, cross ventilation can occur as positive pressure on the windward side and negative pressure on the other sides generate productive pressure differential. The results also demonstrate that DSFs with smaller openings suitably reduce not only the impact of wind pressure, but also the concentration of high air velocity near the windows on the windward side, compared to SSFs. Further insight on indoor airflow behaviors depending on DSF opening configurations leads to a better understanding of the DSF design strategies for effective natural ventilation in tall office buildings.

• Advances in Energy Research
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• v.8 no.2
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• pp.95-110
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• 2022

Wind energy can be utilized for the generation of electricity, due to significant wind potential at different parts of the world, some countries have already been generating of electricity through wind. Pakistan is still well behind and has not yet made any appreciable effort for the same. The objective of this work was to add some new strategies to calculate Weibull parameters and assess wind energy potential. A new approach calculates Weibull parameters; we also developed an alternate formula to calculate shape parameters instead of the gamma function. We obtained k (shape parameter) and c (scale parameter) for two-parameter Weibull distribution using five statistical methods for five different cities in Pakistan. Maximum likelihood method, Modified Maximum likelihood Method, Method of Moment, Energy Pattern Method, Empirical Method, and have been to calculate and differentiate the values of (shape parameter) k and (scale parameter) c. The performance of these five methods is estimated using the Goodness-of-Fit Test, including root mean square error, mean absolute bias error, mean absolute percentage error, and chi-square error. The daily 10-minute average values of wind speed data (obtained from energydata.info) of different cities of Pakistan for the year 2016 are used to estimate the Weibull parameters. The study finds that Hyderabad city has the largest wind potential than Karachi, Quetta, Lahore, and Peshawar. Hyderabad and Karachi are two possible sites where wind turbines can produce reasonable electricity.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.26 no.3
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• pp.29-42
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• 2023

As the destruction of habitats due to recent development continues, there is also increasing interest in endangered species. Mankyua chejuense is a vulnerable species that is sensitive to changes in population and habitat, and it has recently been upgraded from Endangered Species II to Endangered Species I, requiring significant management efforts. So in this study, we analyzed the potential habitats of Mankyua chejuense using MaxEnt(Maximum Entropy) modeling. We developed three models: one that considered only environmental characteristics, one that considered artificial factors, and one that reflected the habitat of dominant tree species in the overstory. Based on previous studies, we incorporated environmental and human influence factors for the habitats of Mankyua chejuense into spatial information, and we also used the habitat distribution models of dominant tree species, including Ulmus parvifolia, Maclura tricuspidata, and Ligustrum obtusifolium, that have been previously identified as major overstory species of Mankyua chejuense. Our analysis revealed that rock exposure, elevation, slope, forest type, building density, and soil type were the main factors determining the potential habitat of Mankyua chejuense. Differences among the three models were observed in the edges of the habitats due to human influence factors, and results varied depending on the similarity of the habitats of Mankyua chejuense and the dominant tree species in the overstory. The potential habitats of Mankyua chejuense presented in this study include areas where the species could potentially inhabit in addition to existing habitats. Therefore, these results can be used for the conservation and management planning of Mankyua chejuense.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.225-225
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• 2022

Rice is a major food crop consumed by approximately half of the world's population. Heading date is one of the major agronomic traits and has a wide impact on the productivity and quality of rice. Recently, shortening the growth period of rice through modulating heading date has been emphasized as one of the most effective strategies for reducing methane emissions from paddy fields. OsPRR37, a major heading date gene in rice, represses flowering under both short-day and long-day conditions. Plants carrying the loss-of-function alleles of OsPRR37 have been reported to flower approximately seven days and 20 days earlier than those carrying the functional alleles in short day and long day conditions, respectively. In this study, we investigated the nucleotide sequence variation existing in the exonic regions of OsPRR37 and catalogued the allelic distribution in 208 Korean rice cultivars. We used four sets of primers for amplifying and sequencing the eight exons of OsPRR37. As a result, two types of loss-of-function alleles and four types of functional alleles were found in 208 Korean rice cultivars. Interestingly, only three cultivars (Jinbuolbyeo, Jinseolchal, and Mimyeon) carried loss-of-function alleles while 205 carried functional alleles, indicating that OsPRR37 loss-of-function alleles have been used very rarely in Korean rice breeding programs. To generate useful information for the development of early-maturing rice cultivars, our future work will focus on analyzing the effect of different OsPRR37 alleles on heading date and other major agronomic traits.

• Korea Trade Review
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• v.48 no.1
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• pp.83-126
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• 2023

The revenue histogram of venture businesses is shifting from bell-shaped normal distribution to power-law distribution, which implies that the fitness landscape of the venture businesses ecosystem is changing to be more rugged terrain. We argue that the firm should adopt both exploitation (fast follower) and exploration (or first mover) strategies not to get stuck in local maxima in the rugged fitness landscape from the complex system perspective. By designing and performing agent-based modeling simulation experiments which consist of three types of agents (new technologies, entrepreneurs, and consumers), we demonstrated that the ambidexterity strategy showed the highest performance score in three of four different environment except 'Fast Widening' case where the exploitation strategy showed the highest performance score under low technology appropriation and fast disruptive technology development speed. By investigating the financial and other statistics of 617 top venture businesses who have earned 100B won or higher annual revenue, we concluded that 82% and 9% of firms are bent on the exploitation and exploration strategy.

• Safety and Health at Work
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• v.14 no.4
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• pp.398-405
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• 2023

Background: Starting from March 2020 until December 2021, different phases of Covid-19 pandemic have been identified in Italy, with several containing/lifting measures progressively enforced by the National government. In the present study, we investigate the change in occupational risk during the subsequent pandemic phases and we propose an estimate of the incidence of the cases by economic sector, based on the analysis of insurance claims for compensation for Covid-19. Methods: Covid-19 epidemiological data available for the general population and injury claims of workers covered by the Italian public insurance system in 2020-2021 were analyzed. Monthly Incidence Rate of Covid-19 compensation claims per 100,000 workers (MIRw) was calculated by the economic sector and compared with the same indicator for general population in different pandemic periods. Results: The distribution of Covid-19 MIRw by sector significantly changed during the pandemic related to both the strength of different waves and the mitigation/lifting strategies enforced. The level of occupational fraction was very high at the beginning phase of the pandemic, decreasing to 5% at the end of 2021. Healthcare and related services were continuously hit but the incidence was significantly decreasing in 2021 in all sectors, except for postal and courier activities in transportation and storage enterprises. Conclusion: The analysis of compensation claim data allowed to identify time trends for infection risk in different working sectors. The claim rates were highest for human health and social work activities but the distribution of risk among sectors was clearly influenced by the different stages of the pandemic.

• Journal of Ecology and Environment
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• v.48 no.1
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• pp.60-73
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• 2024

Background: The available information on terrestrial pest gastropods and their impact on the environment worldwide is scarce and outdated. The present study aimed to address this gap by conducting the first comprehensive survey of pest gastropods in the Nuwara Eliya District, an important vegetable growing area in the highlands of Sri Lanka. Eighty agricultural lands were surveyed over two years by establishing ten 1 m2 sampling plots per crop type in each agricultural land. Geo-coordinates, air temperature, elevation, relative humidity, daily rainfall, soil pH, species richness and abundance were recorded for rainy and non-rainy periods. The relationship between species composition and environmental variables was analyzed using multi-regression models and distribution maps. Results: Out of the 14 species recorded in agricultural lands, nine were identified as exotic pest species. Species abundance (t = 4.69, p < 0.05) and diversity was higher in the rainy period and the dominant species during this period were Bradybaena similaris (t = 2.69, p < 0.05) and Deroceras reticulatum (t = 2. 46, p < 0.05). Eggs and estivating adults were found in soil and under decaying organic matter during the non-rainy period. The exotic species showed broader preferences for the measured environmental factors and showed a wider range in distribution compared to the native species. Variation in pest gastropod composition was significantly accounted for by elevation, relative humidity, soil pH and daily rainfall. Additionally, the species richness and abundance varied across locations due to the combined effects of elevation, crop type and stage, and field type. Conclusions: The study emphasizes the importance of understanding the biology and ecology of gastropod pests to develop effective management strategies. By considering the influence of environmental factors and implementing appropriate soil management techniques, such as targeting specific habitats and crop stages, it is possible to mitigate pest populations and minimize their impact on agricultural lands. Overall, this research contributes valuable insights into the dynamics and interactions of terrestrial gastropods in agricultural ecosystems, supporting sustainable pest management practices.

• Journal of Distribution Science
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• v.14 no.1
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• pp.75-84
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• 2016

Purpose - In accordance with the recent changes in the management environment, leaders are required to have an ability of drawing and inducing potential of each worker. Coaching, as one of the strategies of human resources development, is drawing people's attention. This study aims to inquire about the mechanism of leader's coaching behavior which influences the attitude and behavior of workers. Firstly, this study intends to illustrate what kind of influences the leader's coaching behavior can give on organizational citizenship behavior and turnover intention of workers. Secondly, it plans to verify the mediating effect of authentic leadership in the relationship between leader's coaching behavior and organizational citizenship behavior and turnover intention of workers. Thirdly, it aims to prove the moderating effect of emotional intelligence in the relationship among leader's coaching behavior, organizational citizenship behavior and turnover intention of workers. Research design, data and methodology - In order to figure out how the leader's coaching behavior influences attitude of workers, authentic leadership is considered as mediating effect. As for a moderating effect, we have determined emotional intelligence which attracts attention in the recent studies on organizational behavior, so as to investigate the correlation among variables. As for study sample, it was targeted to 236 organizational members of distribution corporations whose leader's coaching behavior is required. For reaching the purpose of study, SPSS 20 was applied for the analysis. Results - The research findings can be summarized as follows: Firstly, leader's coaching behavior gives significant positive influences on organizational citizenship behavior. Moreover, leader's coaching behavior gives negative influences on turnover intention of organizational members. Secondly, the mediating effect of authentic leadership was proved in the relationship between leader's coaching behavior and attitude of workers. Based on the analysis, it turned out that authentic leadership doesn't give a mediating effect in the bilateral relationship. Lastly, the moderating effect of emotional intelligence was proved in terms of how the leader's coaching behavior influences the attitude of workers. The research result shows that the emotional intelligence influences towards the negative direction, in the correlation between coaching behavior and organizational citizenship behavior On the other hand, in the relationship with turnover intention, It was significant effect. Conclusions - Based on the research findings, we have intended to inquired about the mechanism of leader's coaching behavior which influences the attitude and behavior of workers. Furthermore, in the operational level, the following implications can be given: the importance of coaching activation in the operational level was confirmed, through inquiring into the influence of leader's coaching behavior on workers. Moreover, the importance of emotional intelligence, which has been steadily raised, was also confirmed. It is necessary for future study to carry out additional research on various factors of coaching which can influence the effectiveness of coaching, for instance, coaching process, coach's competency, characteristics of coaching customers, relationship with coaching customers and coaching system.

• Journal of Distribution Research
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• v.11 no.1
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• pp.99-124
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• 2006

The purposes of the study are two-folds. First, it analyzes how factors other than price(e.g. delivery service, saving point policies, free gifts) impact total price for various products and different types of stores. Second, it analyzes how to increase market efficiencies through price level, price differences, and the frequency of price changes for different shops, various products and different types of transactions. By analyzing the price level within different types of stores, there found that prices at on-line store were lower than off-line shops. It also found price differences between pure on-line, hybrid, and off-line store. Comparing prices by product size, there found that pure on-line shops have a lower price compared to others. The results showed that on-line store had lower price variation compared to off-line shops. When comparing pure on-line store to hybrid store, hybrid store had lower price variation. In terms of the frequency of price changes, hybrid stores had higher price fluctuations. In terms of total price differences for delivery distances, pure on-line store had great price fluctuation, excluding cosmetic goods. In conclusion, if we consider price level and price fluctuations, on-line store had more efficiencies and was superior in terms of price effectiveness. Hybrid shops, on the other hand, had greater advantages for seasonal goods and dominant products. Therefore, market entry strategies should differ based on order quantity, type of store(pure on-line, hybrid, off-line), product characteristics(seasonality, product life), etc.